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Bioavailable air concentration of 18 indicator and dioxin-like polychlorinated biphenyls (PCBs) and 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) in the urban air of Dalian, China were simultaneously measured by semipermeable membrane devices (SPMDs). PCB#28, 52, 101, 105 and 118 were the most abundant PCB congeners in Dalian urban air. Phenanthrene, Fluoranthene and Pyrene were the predominat PAH in the air. PCBs were detected with magnitude ranging from non-detectable to 2151 pg SPMD−1. PAHs ranged from non-detectable to 12464 ng SPMD−1. The linear uptake stages of different PCBs and PAHs with SPMD sampling were different. There were much more PCBs during warmer sampling period than colder sampling period, however, there were a reverse results for PAHs. The concentration of some PCBs and PAHs sequestrated by SPMD (CSPMD) in the air has linear correlation with the reciprocal of the average ambient atmospheric temperature (T). The CSPMD of PAHs had negative correlation with T, while the CSPMD of the PCBs had positive correlation with T. The above research results provide basic reference data for the promotion and application of SPMD passive samplers. [ABSTRACT FROM AUTHOR]

Objective. To elucidate the therapeutic efficacy of needle-warming moxibustion (NWM) combined with hyperbaric oxygen therapy (HBOT) in the treatment of patients with ischemic stroke and its effect on neurological function. Methods. One hundred patients with ischemic stroke admitted to the Xuzhou Medical University Affiliated Hospital of Lianyungang from January 2019 to July 2021 were enrolled. Among them, 45 patients treated with NWM were set as the control group, and the rest 55 patients treated by NWM combined with HBOT were included in the research group. The curative effect, neurological deficit score, activity of daily living (ADL), balance ability, and the levels of serum proinflammatory factors in both groups were observed and recorded. Of them, the neurological deficit of patients was evaluated by the National Institutes of Health Stroke Scale (NHISS), the ADL ability was determined by the Barthel index score, and the balance ability was assessed by the Berg balance scale. Results. The total effective rate of the research group was higher than that of the control group. Better ADL and balance ability and milder neurologic impairment were determined in the research group compared with the control group. After treatment, the secretion levels of proinflammatory factors such as C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin-8 (IL-8) in the serum of patients in the research group were statistically lower than those before treatment and the control group. Conclusions. NWM combined with HBOT is effective in the treatment of patients with ischemic stroke, which can not only improve patients' neurological function, ADL, and balance ability but also inhibit serum inflammatory reactions. [ABSTRACT FROM AUTHOR]

This work proposes a framework to examine interactions of climate modes that are identified as leading EOF modes; their coupling structure is unveiled through correlation analysis and helps in constructing a regression model, whose performance is compared across GCMs, thereby providing a quantitative overview of model performances in simulating mode interaction. As a demonstration surface temperature is analyzed for five CMIP5 preindustrial control (PiControl) simulations. Along with the seasonal land and ocean modes, four interannual modes are identified: the tropical mode (TM) associated with the Hadley circulation, the tropical Pacific mode (TPM) characterizing a zonal temperature contrast between the eastern tropical Pacific and the Atlantic/Indian Oceans, and two annular modes, the Arctic mode (AM) and Antarctic mode (AAM). All GCMs converge on the following points: 1) TM strongly couples with seasonal signals of the previous year; 2) TPM leads TM by 1 year, and thus a weaker zonal temperature contrast in the tropics contributes to warming in the entire tropical band 1 year later; and 3) AM weakly couples to TM at a 1-yr lead, suggesting that a colder North Pole may contribute to colder tropics. In addition, all GCMs do not support a linear coupling between AAM and TM. The above-learned coupling structure is incorporated to construct an optimum regression model that demonstrates considerable predictive power. The proposed approach may both serve as a useful tool for dynamical analysis and lend insight into GCM differences. Its merit is demonstrated by the finding that different representations of the mean seasonal cycle in GCMs may account for the GCM dependence of relative contributions of seasonal and interannual modes to TM variability. [ABSTRACT FROM AUTHOR]

Abstract The concentration of short-chain polychlorinated paraffins (SCCPs) in the urban air of Dalian, China was monitored from September 2016 to August 2017 with a self-developed passive sampler (PAS1) and an active high-volume sampler, simultaneously. PAS1 successfully collected the entire target SCCPs in the ambient air. Air SCCPs sampled by PAS1 were found be in the linear uptake stage during 181 days of sampling. Passive and active samples showed comparable congener profiles, and the dominant contributors of SCCPs in the two kinds of samples were similar. A significant linear correlation was observed between the total concentration of SCCPs sampled by PAS1 and active sampler in the four seasons. The passive sampling rates of the PAS1 for the gas and particulate phases of SCCPs were measured. The quantitative structure–property relationship of the sampling rate of PAS1 (R air) for gas-phase SCCPs was studied. From the molecular point of view, R air was mainly affected by the molecular weight and sub-cooled liquid vapor pressure of SCCPs. In general, SCCPs in the urban air of Dalian mainly existed in gas phase, lower molecular weight SCCPs primarily occurred in the gas phase, whereas higher molecular weight SCCPs were predominately adsorbed or absorbed on airborne particles. The air concentration of SCCPs in the four seasons were different, the correlation of the concentration of SCCPs in the air with the meteorology parameters was conducted. The exposure risk by intake air SCCPs of the residents around the sampling sites was evaluated according to the European risk assessment standards. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

A novel photocatalyst, K6ZrW11O39Sn. 12H2O ( ZrW11Sn), was synthesized in our previous study. However, the utilization of ZrW11Sn was extremely limited because of its high solubility in water. A novel composite catalyst, ZrW11Sn-TiO2, was synthesized and characterized in this study. ZrW11Sn-TiO2 is of nanometer-scale and has a structure similar to that of anatase TiO2. The forbidden energy zone of ZrW11Sn-TiO2 is less than that of the synthesized pure TiO2, while its specific surface area is larger. The photocatalytic activities of ZrW11Sn-TiO2 were evaluated by its degradation of monoazo, disazo, anthraquinone, and three aryl methane dyes with solar irradiation in heterogeneous aqueous solutions. Results indicate that ZrW11Sn-TiO2 has higher photocatalytic activity than the synthesized pure TiO2, commercial anatase TiO2, H3PW12O40, and H4SiW12O40 doped TiO2. The optimum doping concentration of ZrW11Sn and the calcination temperature were 1.8 wt % ( ZrW11Sn) and 400°C, respectively. ZrW11Sn-TiO2 showed a considerably high photocatalytic stability. When a Reactive Black 5 solution (200 mL, 10 mg/L; initial pH 6) with ZrW11Sn-TiO2 (0.2 g/L) was irradiated for 60 min with simulated sunlight, the decoloration rate was >98% even after four cycles. ZrW11Sn-TiO2 exhibited a better settling property than commercial TiO2, which made further separation treatment easier. [ABSTRACT FROM AUTHOR]

Polyoxometalate, K6TiW11O39Sn·7H2O (TiW11Sn), was synthesized and characterized. TiW11Sn and K6ZrW11O39Sn·12H2O (ZrW11Sn) were evaluated for their photocatalytic degradation of triarylmethane (brilliant green and acid blue 9), bisazo (C.I. reactive black 5), and monoazo dyestuffs (C.I. reactive red 24, C.I. reactive red 194, and C.I. reactive orange 5) with natural sunlight in homogeneous aqueous solutions. TiW11Sn and ZrW11Sn effectively and photocatalytically decolorized the dyestuffs. The TiW11Sn- and ZrW11Sn-mediated photocatalytic degradation of the dyestuffs involved a pseudo-first-order reaction and was modeled by Langmuir–Hinshelwood-type kinetics. The observed pseudo-first-order rate constants (K/) of triarylmethane dyestuffs were generally bigger than that of the azo dyestuffs. Quantitative structure–property relationship models of theK/of the dyestuffs were developed using partial least-square regression. The cumulative variance of the dependent variable explained by the partial least-square components was > 0.753 for each optimal model. This value indicated that the model had good predictive ability and robustness. TheK/values of the dyestuffs were related to the energy of the lowest unoccupied molecular orbital, and the most positive net atomic charges on a sulfur atom of dyestuffs. The linear correlation coefficients between the predicted and experimental values were all > 0.9950. [ABSTRACT FROM AUTHOR]

Climate variability is often studied in terms of fluctuations with respect to the mean state, whereas the dependence between the mean and variability is rarely discussed. Here, a new climate metric is proposed to measure the relationship between means and standard deviations of annual surface temperature computed over nonoverlapping 100-yr segments. This metric is analyzed based on equilibrium simulations of the Max Planck Institute Earth System Model (MPI-ESM): the last-millennium climate (800-1799), the future climate projection following the A1B scenario (2100-99), and the 3100-yr unforced control simulation. A linear relationship is globally observed in the control simulation and is thus termed intrinsic climate variability, which is most pronounced in the tropical region with negative regression slopes over the Pacific warm pool and positive slopes in the eastern tropical Pacific. It relates to asymmetric changes in temperature extremes and associates fluctuating climate means with increase or decrease in intensity and occurrence of both El Niño and La Niña events. In the future scenario period, the linear regression slopes largely retain their spatial structure with appreciable changes in intensity and geographical locations. Since intrinsic climate variability describes the internal rhythm of the climate system, it may serve as guidance for interpreting climate variability and climate change signals in the past and the future. [ABSTRACT FROM AUTHOR]

Interdecadal variability of observed winter precipitation in Southeast China (1961-2010) is characterized by the first empirical orthogonal function of the three-monthly Standardized Precipitation Index (SPI) subjected to a 9-year running mean. For interdecadal time scales the dominating spatial modes represent monopole features involving the Arctic Oscillation (AO) and the sea surface temperature (SST) anomalies. Dynamic composite analysis (based on NCEP/NCAR reanalyzes) reveals the following results: (1) Interdecadal SPI-variations show a trend from a dryer state in the 1970s via an increase during the 1980s towards stabilization on wetter conditions commencing with the 1990s. (2) Increasing wetness in Southeast China is attributed to an abnormal anticyclone over south Japan, with northward transport of warm and humid air from the tropical Pacific to South China. (3) In mid-to-high latitudes the weakened southward flow of polar airmasses induces low-level warming over Eurasia due to stronger AO by warmer zonal temperature advection. This indicates that AO is attributed to the Southeast China precipitation increase influenced by circulation anomalies over the mid-to-high latitudes. (4) The abnormal moisture transport along the southwestern boundary of the abnormal anticyclone over south Japan is related to anomalous south-easterlies modulated by the SST anomalies over Western Pacific Ocean; a positive (negative) SST anomaly will strengthen (weaken) warm and humid air transport, leading to abundant (reduced) precipitation in Southeast China. That is both AO and SST anomalies determine the nonlinear trend observed in winter precipitation over Southeast China. [ABSTRACT FROM AUTHOR]

The concentrations of 28 organochlorine pesticides (OCPs) in the urban air of Dalian, China were measured using semipermeable membrane devices (SPMDs) for the first time. Alpha-hexachlorocyclohexane (α-HCH), β-HCH, pentachlorobenzene (PentCB), hexachlorobenzene (HexCB), 4,4′-dichlorodiphenyltrichloroethane (4,4′-DDT), 4,4′-dichlorodiphenyldichloroethene, endosulfan-I and endosulfan-II were the predominant OCPs in the urban air of Dalian. The concentration of OCPs sequestrated by SPMDs ( C) ranged from undetected to 56,772 pg SPMD and had a linear correlation with the reciprocal of the average ambient atmospheric temperature (1 /T). The C of PentCB and HexCB had negative correlations with T, whereas the other detected OCPs had a positive correlation. The source of HCHs, DDTs, HexCB, PentCB, chlordane, and endosulfan in the air were also evaluated. The OCPs in the urban air of Dalian could be attributed to the seasonal usage of pesticides, combustion, volatilization of aged OCPs from soil, water, plants, and long-range atmospheric transport. [ABSTRACT FROM AUTHOR]

This paper uses the 42-yr German Estimating the Circulation and Climate of the Ocean (GECCO) synthesis data to analyze and examine the relationship of the Indian Ocean deep meridional overturning circulation (DMOC) with the Indian Ocean dipole mode (IOD). Contributions of various dynamical processes are assessed by decomposing the DMOC into the Ekman and geostrophic transport, the external mode, and a residual term. The first three terms successfully describe the DMOC with a marginal residual term. The following conclusions are obtained. First, the seasonal cycle of the DMOC is mainly determined by the Ekman component. The exception is during the transitional seasons (March-April and September-October) in the northern Indian Ocean Basin, where the geostrophic component dominates. Second, at the beginning phase of the IOD (May-June), the Ekman component dominates the DMOC structure; at and after the peak phase of the IOD (September-December), the DMOC structure is primarily determined by the geostrophic component in correspondence with the well-developed sea surface temperature anomalies, while the wind (and thus the Ekman component) plays a secondary role south of 10°S and contributes negatively within the zonal band of 10° on both sides of the equator. Therefore, there exists a surface to deep-ocean connection through which IOD-related surface wind and ocean temperature anomalies are transferred down to the deep ocean. Westward-propagating signals are observed even in the deep ocean, suggesting possible roles of Rossby waves in transferring the surface signal to the deep ocean. [ABSTRACT FROM AUTHOR]

The authors use a statistical regional climate model [Statistical Regional Model (STAR)] to project the Tibetan Plateau (TP) climate for the period 2015-50. Reanalysis datasets covering 1958-2001 are used as a substitute of observations and resampled by STAR to optimally fit prescribed linear temperature trends derived from the Max Planck Institute Earth System Model (MPI-ESM) simulations for phase 5 of the Coupled Model Intercomparison Project (CMIP5) under the representative concentration pathway 2.6 (RCP2.6) and RCP4.5 scenarios. To assess the related uncertainty, temperature trends from carefully selected best/worst ensemble members are considered. In addition, an extra projection is forced by observed temperature trends in 1958-2001. The following results are obtained: (i) Spatial average temperature will increase by 0.6°-0.9°C; the increase exceeds 1°C in all months except in boreal summer, thus indicating a reduced annual cycle; and daily minimum temperature rises faster than daily maximum temperature, resulting in a narrowing of the diurnal range of near-surface temperature. (ii) Precipitation increase mainly occurs in early summer and autumn possibly because of an earlier onset and later withdrawal of the Asian summer monsoon. (iii) Both frost and ice days decrease by 1-2 days in spring, early summer, and autumn, and the decrease of frost days on the annual course is inversely related to the precipitation increase. (iv) Degree-days increase all over the TP with peak amplitude in the Qaidam Basin and the southern TP periphery, which will result in distinct melting of the local seasonal frozen ground, and the annual temperature range will decrease with stronger amplitude in south TP. [ABSTRACT FROM AUTHOR]

The concentration of polycyclic aromatic hydrocarbons (PAHs) in the urban air of Dalian, China was monitored from November 2009 to October 2010 with an active high-volume sampler and a semipermeable membrane device (SPMD) passive sampler. The samples were analyzed for the sixteen US EPA priority monitoring PAHs using GC/MS. The concentrations of ∑PAHs in particle and gas phases ranged from 3.2–90.6 ng m−3and 40.8–155 ng m−3, respectively. The PAHs of 3–4 rings covered 89.2% of the total concentrations (gas phase + particle phase). Furthermore, the gas-particle partitioning phenomena and the results measured from the field versus those predicted by the Junge-Pankow adsorption model, octanol-air partitioning coefficient (KOA) based absorption model, the absorption into the organic matter plus the adsorption to the soot carbon model using the soot-air partitioning coefficients (KSA) were discussed in this article. The dominant contributors of PAHs in the gas phase of active samples and SPMD passive samples were similar. The SPMD mainly sequestrated gas phase PAHs. The linear correlation coefficients betweenCSPMDandCair-gaswere 0.7316 and 0.7403;CSPMDandCair-totalwere 0.7397 and 0.7409 at Dalian Jiaotong University sampling site and Dalian Meteorological Observatory sampling site, respectively. The quantitative structure-property relationship (QSPR) of the sampling rate of SPMD for PAHs was studied, which can be predicted by the core–core repulsion energy and the energy of the highest occupied molecular orbital of PAH molecules. [ABSTRACT FROM AUTHOR]

To evaluate the gas-particle partitioning behavior of polycyclic aromatic hydrocarbons (PAHs) in the urban air of Dalian, China, both gas phase and particle phase ambient air were monitored with active high-volume sampler from November 2009 to October 2010. The average total concentration of 16 US EPA priority monitoring PAHs (particle + gas) (?PAHs) was 112 ng m?3and the most abundant PAH was Phenanthrene. ?PAHs and the gas-particle partitioning coefficients (Kp) of PAHs displayed seasonal variation in the order of winter > autumn > spring > summer. ?PAHs was much higher during the heating period than non heating period. ?PAHs in gas phase were all higher than those in particle phase in the four seasons. The PAHs sources identification was attempted using diagnostic ratios. The relationship between the concentration of PAHs in the air and meteorology parameters were analyzed using SPSS packages. The concentrations of PAHs in the air decreased with the increase of ambient temperature, and increased with the increase of atmospheric pressure. The gas-particle distribution was examined through several different approaches such as the relationship of logKpwith the ambient temperature, with the logarithm of the sub-cooled vapor pressure (logPL0), and the octanol-air partitioning coefficient (logKoa) of PAHs. The slopes obtained from regressing logKpvs. logPL0was ?0.687??0.821 in heating periods, which was in the range between ?0.6 and ?1, indicating the partitioning of PAHs to particle phase in the urban air of Dalian was absorption as well as for adsorption mechanism. However, the average slope value was ?0.502 in the non heating periods, which was shallower than -0.60, indicating that the absorption mechanisms contributed more to the partitioning process. The exposure risk of PAHs was evaluated with four methods, the results of which indicated that the quality of the urban air of Dalian was better. [ABSTRACT FROM PUBLISHER]

PCDD/Fs in the urban air of Dalian, China were monitored with high-volume active sampler from November 2009 to October 2010. The concentration of ClDD/Fs ranged from 3065 to 49538 fg m, with an average of 10249 fg m. The international toxic equivalents (I-TEQ) value of that was 61.8-1182 fg m, with an average of 235 fg m, which was comparable to those in the other urban locations around the world. It was found that the ClDD/Fs appeared to be present mainly in the particle phase during winter, spring and autumn, while during summer which were dominantly in gas phase. The ratio of ClDD/Fs present in particle phase increased with the increasing level of chlorination. The concentrations of PCDFs and PCDDs decreased with the increase of chlorinated level, while the concentrations of 2,3,7,8-PCDDs congeners increased with the increase of chlorination level. The homolog profiles of the concentrations of PCDFs presented were higher than those of the PCDDs, which indicated the PCDD/Fs pollution source of the air in Dalian was characteristic for thermal source pollution. The correlation analysis of meteorological parameters with the concentrations of ClCDD/Fs was conducted using SPSS packages, and it was found that the ambient temperature and atmospheric pressure were important factors influence the concentration of PCDD/Fs in the air. The respiratory risk and intake dioxins of the residents around the sampling sites were studied in the paper. It was found that Junge-Pankow model was much more accurate in predicting the gas-particle partitioning behavior of PCDD/Fs homologues during winter, while the Harner-Bidleman model shows better agreement with the measured data during winter and summer. [ABSTRACT FROM AUTHOR]

Abstract: Variability of the Yangtze catchment hydrology is closely linked with the Tibetan Plateau snow cover and the large scale atmospheric circulation in East Asia. These connections are analyzed in a control simulation (2800 years) of the atmosphere–ocean general circulation model (ECHAM5/MPIOM) coupled to vegetation and ocean biogeochemistry modules. (i) Up to decades in time scale, runoff, soil wetness, and temperature show long term memory (LTM) with an intradecadal scaling of the power spectrum with the exponent β ≈ 0.6, while precipitation, snow depth, and snow melt reveal no memory. (ii) Multi-decadal variability of runoff, soil wetness, and temperature shows weak LTM similar to snow depth and melt on the Tibetan Plateau. (iii) On the annual time scale, the atmospheric circulation impact of Hadley cell and ENSO on precipitation, temperature and snow melt are weak but significant; on decadal time scales the subtropical monsoon modulates the catchment hydrology. Temperature is anticorrelated with precipitation and soil wetness in the Yangtze catchment. Singular spectrum analysis highlights the 3–4 year ENSO mode in the monsoon indices, precipitation, and snow depth, explaining their high correlations. Projecting snow depth on ENSO shows long term variations explaining conflicting results obtained from correlations in short data sets. [Copyright &y& Elsevier]

Abstract: Based on the ERA-40 reanalysis data, dryness and wetness over the Tibetan Plateau are categorized according to the monthly standardized precipitation index. The atmospheric features associated with severe and extreme dryness and wetness reveal two cross-Eurasia wave trains: the Scandinavia-East Asia wave train and the Mediterranean-East Asia wave train. Severe and extreme dryness is associated with an anomalous cyclone over south and southeast Asia, which directs the moisture supply from the Arabian Sea, the Bay of Bengal, and the South China Sea directly eastward towards the western Pacific, thus bypassing the Tibetan Plateau. This cyclone anomaly constitutes part of the Scandinavia-East Asia wave train, which is sustained by the divergence and convergence of the anomalous transient eddy heat transport associated with a more southwest-northeast oriented North Atlantic storm track and a northward shift of the polar front jet in the North Atlantic. In contrast, severe and extreme wetness over the Tibetan Plateau is associated with a more zonally elongated North Atlantic storm track; wave trains excited from there have a high probability to reach the Mediterranean region and to propagate eastward following the subtropical westerly jet. This Mediterranean-East Asia wave train generates anticyclonic anomalies around the Tibetan Plateau and East China, which bring more moisture supply from the Arabian Sea, the South China Sea, and the western Pacific towards the Tibetan Plateau and enhance the moisture convergence there. This paper demonstrates how atmospheric bridging processes affect regional climate variability under present day climatic conditions, which are also relevant for understanding past climates. [Copyright &y& Elsevier]

The contaminated air with burning plastic floor and electronic scrap was monitored with semipermeable membrane devices (SPMDs) and fresh unpolluted spruce needles at the same time for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs). It was found that there were more polychlorinated dibenzofurans (PCDFs) than polychlorinated dibenzo-p-dioxins (PCDDs) collected from contaminated air. The total amounts of PCBs were much higher than that of PCDD/Fs, but the contribution of them to the WHO-TEQ was less than that of PCDD/Fs. Triolein-containing SPMDs can absorb much more PCDD/Fs and PCBs than spruce needles when they were exposed in contaminated air simultaneously. The logarithm of the concentrations of PCDD/Fs and PCBs in SPMDs and in spruce needles at the same sampling time exhibited a significant linear correlation, the correlation coefficients were larger than 0.86 for PCDD/Fs and 0.92 for PCBs. SPMDs and spruce needles are effective passive air sampler for PCDD/Fs and PCBs. SPMDs and spruce needles can complement each other in passive air sampling. [Copyright &y& Elsevier]

• Heavy metal pollution was investigated in the main rivers across China. • Zn, Cu and Cr exhibited higher levels in the north, while Cd, Tl, and As were opposite. • Tl in surface water collected in the south is 9 times higher than that in the north. • Major contributing elements for HQ and CR are geographically different. Rapid urbanization accelerates the release of anthropogenic heavy metals from local to wider water systems, posing a serious threat to aquatic ecosystems and public health. The characteristics of trace elements were investigated to evaluate the environmental status of surface water in 40 cities of China. The concentrations of 22 elements in surface water ranged from 7.00 × 10−4 to 4.37 × 105 μg/L. The water quality can be classified as "excellent" except Songhuajiang. The levels of As, Cd, Cr, Pb, and Hg are all within the limits permitted by national drinking water quality standards. An obvious regional distribution characteristic was observed, with concentrations of Zn, Mn, Ni, Cu, Co, U, and Cr higher in surface water collected in the north than in the south, while the trends for Cd, Tl, and As are opposite. Notably, Tl shows significant geographical divergences, with the level of surface water collected from the south nine times higher than that from the north. The regional distribution of the mineral, industrial, or agricultural activity might be responsible for the south-to-north difference of these elements. The hazard index (HI) and total cancer risk (TCR) through oral or dermal contact with water-related heavy metals were further calculated. The average HI was 0.54 in the north and 0.29 in the south for adults, while HI for children was relatively higher. The value was 1.01 and 0.55 in the north and south, respectively. TCR in the north is 2.58 × 10−4 and mainly contributed by Cr (88.1 %), while TCR in the south is 4.48 × 10−5 and mainly contributed by As (98.4 %). The research results can provide essential data for effective water resources management and human health protection in China. [Display omitted] [ABSTRACT FROM AUTHOR]

How the Atlantic multidecadal oscillation (AMO) affects El Niño–related signals in Southeast Asia is investigated in this study on a subseasonal scale. Based on observational and reanalysis data, as well as numerical model simulations, El Niño–related precipitation anomalies are analyzed for AMO positive and negative phases, which reveals a time-dependent modulation of the AMO. 1) In May–June, the AMO influences the precipitation in southern China (SC) and the Indochina peninsula (ICP) by modulating the El Niño–related air–sea interaction over the western North Pacific (WNP). During negative AMO phases, cold sea surface temperature anomalies (SSTAs) over the WNP favor the maintaining of the WNP anomalous anticyclone (WNPAC). The associated southerly (westerly) anomalies on the northwest (southwest) flank of the WNPAC enhance (reduce) the climatological moisture transport to SC (the ICP) and result in wetter (drier) than normal conditions. In contrast, during positive AMO phases, weak SSTAs over the WNP lead to limited influence of El Niño on precipitation in Southeast Asia. 2) In July–August, the teleconnection impact from the North Atlantic is more manifest than that in May–June. During positive AMO phases, the warmer than normal North Atlantic favors anomalous wave trains, which propagate along the "great circle route" and result in positive pressure anomalies over SC, consequently suppressing precipitation in SC and the ICP. During negative AMO phases, the anomalous wave trains tend to propagate eastward from Europe to Northeast Asia along the summer Asian jet, exerting limited influence on Southeast Asia. [ABSTRACT FROM AUTHOR]

The thermal forcing of the Tibetan Plateau (TP) is analyzed to investigate the formation and variability of Tibetan Plateau Summer Monsoon (TPSM), which affects the climates of the surrounding regions, in particular the Indian summer monsoon precipitation. Dynamic composites and statistical analyses indicate that the Indian summer monsoon precipitation is less/greater than normal during the strong/weak TPSM. Strong (weak) TPSM is associated with an anomalous near surface cyclone (anticyclone) over the western part of the Tibetan Plateau, enhancing (reducing) the westerly flow along its southern flank, suppressing (favoring) the meridional flow of warm and moist air from the Indian ocean and thus cutting (providing) moisture supply for the northern part of India and its monsoonal rainfall. These results are complemented by a dynamic and thermodynamic analysis: (i) A linear thermal vorticity forcing primarily describes the influence of the asymmetric heating of TP generating an anomalous stationary wave flux. Composite analysis of anomalous stationary wave flux activity (after Plumb in J Atmos Sci 42:217-229, 1985) strongly indicate that non-orographic effects (diabatic heating and/or interaction with transient eddies) of the Tibetan Plateau contribute to the generation of an anomalous cyclone (anti-cyclone) over the western TP. (ii) Anomalous TPSM generation shows that strong TPSM years are related to the positive surface sensible heating anomalies over the eastern TP favoring the strong diabatic heating in summer. While negative TPSM years are associated with the atmospheric circulation anomalies during the preceding spring, enhancing northerly dry-cold air intrusions into TP, which may weaken the condensational heat release in the middle and upper troposphere, leading to a weaker than normal summer monsoon over the TP in summer. [ABSTRACT FROM AUTHOR]

Environmental friendly materials, K 6 SiW 11 O 39 Sn (SiWSn), was synthesized. SiWSn photocatalytic decomposition of C. I. Reactive Red 24 (RR24) with the UV-lamp (253.7 nm, 20 W), Xenon lamp filtered less than 390 nm light (500 W) and sun light was investigated. The results showed that RR24 solution could be effectively decolorized with the SiWSn photocatalyst. The photocatalytic degradation efficiency of RR24 with SiWSn was affected by the initial concentration of RR2 solution, the amount of SiWSn and the photolysis time. It is demonstrated that the process of photodegradation of RR24 with SiWSn is a pesudo first-order reaction, which can be described by Langmuir-Hinshelwood equation. Hydroxyl radicals and holes are both the main oxidants in the photocatalytic reaction of RR24 with SiWSn. [ABSTRACT FROM AUTHOR]

Chlorinated paraffins (CPs) are chlorinated alkane mixtures widely used as flame retardants and plasticizers in multiple industrial products. Systematic research on how homolog-specific properties affect their atmospheric behaviors is limited. Herein, we investigated the levels of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) in long-timescale, seasonal, and size-fractioned particles in the urban area of Dalian, a coastal city in northern China. The average SCCP and MCCP concentrations in particles with diameters ≤ 10 µm were 3.36 and 4.89 ng/m3, respectively, and a general increase in the SCCP concentration was observed from 2.59 ng/m3 in 2018 – 2019 to 7.84 ng/m3 in 2021 – 2023. CP levels and patterns showed significant seasonal variation, with a higher abundance of C 11–13 Cl 7–9 in winter and C 10–12 Cl 5 in summer. Elevated particle levels in winter and high temperatures in summer contributed to the seasonal variations. SCCPs and MCCPs were concentrated on particles with diameters of < 1 µm and their geometric mean diameter increased with the increasing carbon and chlorine numbers. Total Daily intake of SCCP and MCCP was calculated to be 0.15 and 0.22 ng/kg bw/day for adults. 53.1 %, 8.5 %, and 38.4 % of inhaled SCCPs, and 60.6 %, 7.6 %, and 31.8 % of inhaled MCCPs deposited into the head airway, tracheobronchial region, and alveolar region, respectively. This study reports on how homolog-specific physicochemical properties alter the temporal variations, size distributions, and inhaled fractions of CPs. [Display omitted] • SCCP concentrations increased from 2.59 ng/m3 in 2018-2019 to 7.84 ng/m3 in 2021-2023. • Particle level and temperature influenced the seasonal variations of SCCPs and MCCPs. • CPs with more carbon and chlorine atoms were dominant in larger particles and deposited more into the respiratory system. • Only 32.4 % of the inhaled SCCPs and 37.5 % of the MCCPs were deposited in the respiratory region. [ABSTRACT FROM AUTHOR]

We report an in situ synthesis of α-Fe 2 O 3 /LaFeO 3 compounded with g-C 3 N 4 and Ti 3 C 2 MXene to form multiple Z-scheme/Schottky heterojunctions, α-Fe 2 O 3 /LaFeO 3 /g-C 3 N 4 /Ti 3 C 2 (FLCT). In FLCT, α-Fe 2 O 3 /LaFeO 3 promoted carrier migration, g-C 3 N 4 caused electrons to move directionally toward Ti 3 C 2 , inhibiting the carrier complex, and the Ti 3 C 2 substitution of a noble metal provided more adsorption active sites and promoted carrier separation. The synergistic effect of the multiple Z-scheme/Schottky heterojunctions endowed the FLCT composite with an excellent photocatalytic performance. To demonstrate the extensive applicability of the composite materials in the photocatalytic degradation and reduction of wastewater, methylene blue (MB), rhodamine B (Rh B), tetracycline hydrochloride (TC), and hexavalent chromium ions (Cr (VI)) were used as model pollutants; 91.30% of the MB, 84.32% of the Rh B, and 76.11% of the TC were photocatalytic degraded. In addition, 79.60% of the Cr (VI) was photocatalytically reduced by FLCT. These results showed that the composite catalyst exhibited photocatalytic degradation or reduction efficiencies that were 3.41-, 3.86-, 5.44-, and 4.14-fold greater than those of pure LaFeO 3 for MB, Rh B, TC, and Cr (VI), respectively. The intrinsic relationship between the composite structure and the photocatalytic performance was investigated to reveal the enhancement mechanism of the composite photocatalytic performance. The charge migration path and pollutant degradation mechanism in the photocatalytic system were elucidated. This work provides a novel concept for designing heterojunction-structured photocatalysts and provides an experimental foundation for photocatalytic technology to treat water pollution. [Display omitted] • In situ synthesis α-Fe 2 O 3 /LaFeO 3 compounded with g-C 3 N 4 and Ti 3 C 2 MXene. • Ti 3 C 2 substitution of a noble metal provide more adsorption active sites and promote carrier separation. • Multiple Z-scheme/Schottky heterojunctions exhibit multipurpose pollutant photodegradation. [ABSTRACT FROM AUTHOR]

The observed relation of worldwide precipitation maxima P versus duration d follows the Jennings scaling law, P ≈ d b, with scaling coefficient b ≈ 0.5. This scaling is demonstrated to hold for single-station rainfall extending over three decades. A conceptual stochastic rainfall model that reveals similar scaling behavior is introduced as a first-order autoregressive process [AR(1)] to represent the lower tropospheric vertical moisture fluxes, whose upward components balance the rainfall while the downward components are truncated and defined as no rain. Estimates of 40-yr ECMWF Re-Analysis (ERA-40) vertical moisture flux autocorrelations (at grids near the rainfall stations) provide estimates for the truncated AR(1). Subjected to maximum depth-duration analysis, the scaling coefficient b ≈ 0.5 is obtained extending for about two orders of magnitude, which is associated with a wide range of vertical moisture flux autocorrelations 0.1 < a < 0.7. [ABSTRACT FROM AUTHOR]

The precipitation climate in the larger Tian Shan region of Central Asia is described in terms of the climatological seasonal moisture fluxes and background circulation based on the ERA-40 reanalysis data and a precipitation reanalysis. The study area is partitioned into (1) the Tarim river basin, (2) bordering regions of China, Kyrgyzstan and Kazakhstan, and (3) Northwestern China. Moisture supply to these areas is primarily due to the midlatitude westerlies with contributions from higher latitudes. In addition, moisture from the Indian Ocean is notably imported into the Tarim drainage area. Monthly interannual precipitation variability relates to the variability of hemispheric circulation patterns. Extreme precipitation above and below normal in Western China and Central Asia is analyzed using the standardized precipitation index. Related circulation composites show that, despite regional and seasonal differences, episodes of extreme and severe dryness are dominated by various upstream standing wave patterns from the North Atlantic to Central Asia. These features extend further downstream to the North Pacific. Non-symmetry between wet and dry composites is noted upstream and in regional moisture flux composites. [ABSTRACT FROM AUTHOR]

Relations between Tibetan Plateau precipitation and large-scale climate indices are studied based on the Standardized Precipitation Index (SPI) and the boreal summer season. The focus is on the decadal variability of links between the large-scale circulation and the plateau drought and wetness. Analysis of teleconnectivity of the continental northern hemisphere standardized summer precipitation reveals the Tibetan Plateau as a major SPI teleconnectivity center in south-eastern Asia connecting remote correlation patterns over Eurasia. Employing a moving window approach, changes in covariability and synchronizations between Tibetan Plateau summer SPI and climate indices are analyzed on decadal time scales. Decadal variability in the relationships between Tibetan Plateau summer SPI and the large-scale climate system is characterized by three shifts related to changes in the North Atlantic, the Indian Ocean, and the tropical Pacific. Changes in the North Atlantic variability (North Atlantic Oscillation) result in a stable level of Tibetan Plateau summer SPI variability; the response to changes in tropical Pacific variability is prominent in various indices such as Asian monsoon, Pacific/North America, and East Atlantic/Western Russia pattern. [ABSTRACT FROM AUTHOR]

Continuum temperature variability represents the response of the Earth's climate to deterministic external forcing. Scaling regimes are observed which range from hours to millennia with low frequency fluctuations characterizing long-term memory. The presence of 1/f power spectra in weather and climate is noteworthy: (i) In the tropical atmosphere 1/f scaling ranging from hours to weeks is found for several variables; it emerges as superposition of uncorrelated pulses with individual 1/f spectra. (ii) The daily discharge of the Yangtze shows 1/f within one week to one year, although the precipitation spectrum is white. (iii) Beyond one year mid-latitude sea surface temperatures reveal 1/f scaling in large parts of the global ocean. The spectra can be simulated by complex atmosphere-ocean general circulation models and understood as a two layer heat diffusion process forced by an uncorrelated stochastic atmospheric. Long-term memory on time scales up to millennia are the global sea surface temperatures and the Greenland ice core records (GISP2, GRIP) with δ18O temperature proxy data during the Holocene. Complex atmosphere ocean general circulation models reproduce this behavior quantitatively up to millennia without solar variability, interacting land-ice and vegetation components. [ABSTRACT FROM AUTHOR]

Abstract: A global spectral barotropic ocean model is introduced to describe the depth-averaged flow. The equations are based on vorticity and divergence (instead of horizontal momentum); continents exert a nearly infinite drag on the fluid. The coding follows that of spectral atmospheric general circulation models using triangular truncation and implicit time integration to provide a first step for seamless coupling to spectral atmospheric global circulation models and an efficient method for filtering of ocean wave dynamics. Five experiments demonstrate the model performance: (i) Bounded by an idealized basin geometry and driven by a zonally uniform wind stress, the ocean circulation shows close similarity with Munk’s analytical solution. (ii) With a real land–sea mask the model is capable of reproducing the spin-up, location and magnitudes of depth-averaged barotropic ocean currents. (iii) The ocean wave-dynamics of equatorial waves, excited by a height perturbation at the equator, shows wave dispersion and reflection at eastern and western coastal boundaries. (iv) The model reproduces propagation times of observed surface gravity waves in the Pacific with real bathymetry. (v) Advection of tracers can be simulated reasonably by the spectral method or a semi-Langrangian transport scheme. This spectral barotropic model may serve as a first step towards an intermediate complexity spectral atmosphere–ocean model for studying atmosphere–ocean interactions in idealized setups and long term climate variability beyond millennia. [Copyright &y& Elsevier]

Based on the NCEP/NCAR reanalysis data, the COBE sea surface temperature (SST) and the GPCC precipitation, the influences of El Niño-South Oscillation (ENSO) on the variability of winter rainfall anomalies in Southeast China is analyzed under the synergistic effect of Indian Ocean Dipole (IOD). Winter precipitation and atmospheric circulation of the years of IOD concurring with ENSO are compared with single IOD or ENSO, to reveal the mechanism of synergistic effects on the variability of winter rainfall anomalies in Southeast China. The results show that the correlation between IOD/ENSO and the winter precipitation in Southeast China has increased since 1980s. These correlations were significant in years of IOD and ENSO co-occurrence compared to years of IOD or ENSO only, which is mainly due to the lagged atmospheric thermal and dynamic responses to an IOD forcing in synergy with ENSO. The positive IOD (PIOD) events can trigger and modify the anticyclone to the east of India, which transports moisture from the tropical Indian Ocean to Southeast China. In addition, El Niño events can strengthen the abnormal anticyclone over Philippines in winter, which is conducive to maintain the water vapor channel from the tropical western Pacific to Southeast China. Information flow analysis shows that the causalities between IOD and ENSO were enhanced after 1980s, causing the significant increase in the frequency of winter abnormal precipitation in the years of IOD and ENSO concurrence. Furthermore, the higher frequency of PIOD with El Niño (compared to negative IOD with La Niña) attained a ratio of 2:1 after the 1980s, enhancing the Southeast China winter precipitation events associated with IOD and ENSO and the generation of interdecadal variability. This study is helpful to understand the mechanisms of winter precipitation changes in Southeast China, and to improve the forecast accuracy of winter extreme precipitation events. [ABSTRACT FROM AUTHOR]

The interannual variability of precipitation during the summer monsoon transition over the Indochina Peninsula (ICP) is substantially influenced by the sea surface temperature anomalies (SSTAs) of the tropical ocean, showing a robust relationship between April and May (AM) precipitation and the El Niño/Southern Oscillation (ENSO) phenomenon. Dynamic composites and statistical analyses supported by model experiments indicate that the observed anomalous AM precipitation is associated with circulation anomalies over the Pacific and, in addition, affected by the response to the tropical SSTAs forcing from the Indian Ocean (IO): (i) Less (greater) than normal AM precipitation over the ICP occurs during the El Niño (La Niña) years, which is consistent with late (early) Bay of Bengal (BoB) summer monsoon onset. (ii) The dry (wet) AM precipitation years are associated with the anomalous western North Pacific (WNP) anti-cyclone (cyclone) induced by El Niño (La Niña) concurrent with the anti-cyclone (cyclone) over the BoB, suppressing (favoring) the meridional flow of warm and moist air from the Pacific and Indian ocean and thus cutting (providing) moisture supply for the ICP. (iii) The reduced tropical convective activity over Maritime Continent (MC) is related to the weakened local Hadley circulation concurrent with the weakened overturning Walker circulation, and favors a drier than normal AM precipitation over the ICP, to which the wetter years are opposite. These symmetric atmospheric circulation patterns characterizing dry and wet AM precipitation over the ICP are also reproduced by numerical experiments with an atmospheric general circulation model. [ABSTRACT FROM AUTHOR]

Magnetic records in sedimentary sequences are often used as paleoclimate proxies. Climate‐specific alteration of magnetite during rock weathering in the catchment might contribute to proxy variations in sediment sinks. In an actualistic study, we investigated the effects of magnetite alteration using weathered pebble material on basaltic parent rock. We collected samples from the Deccan basalts (India) across a large difference of mean annual precipitation (MAP; ∼800–3,200 mm), and also from the Emeishan basalts (SW‐China) to compare alteration effects at similar MAP (∼1,100 mm) but ∼12°C–15°C lower mean annual temperature (MAT). We used rocks with lamellar magnetite‐ilmenite texture to ensure the best possible uniform parent rock magnetic mineralogy. We separated the weathered material into five groups by grain size, assuming that alteration increases in finer pebbles. Only magnetic susceptibility (χ) shows a systematic change, with an increase that is weakly stronger for higher MAP. Consistent with a simplified model, the χ‐increase may represent progressive maghemitization. For the Emeishan basalts, we found a significantly stronger degree of alteration, including loss of magnetite. We explain this effect, which is surprising regarding the clearly lower MAT, by frost‐induced micro‐cracks due to physical weathering that opens pathways for oxygen and humidity into particle interiors. Based on these findings, we conclude that climate‐related alteration effects of magnetite during rock weathering are in most cases outweighed by parent rock heterogeneity, and magnetic proxy records in derived sediment archives are unlikely to record climate‐related magnetite alteration acquired during rock weathering, at least for catchment with basalts. Plain Language Summary: Magnetite is of primary importance for magnetic records in paleoclimate archives such as lake sediments. Source material for archives derives from bedrock weathering. Possible climate‐dependent alteration of magnetite during rock weathering may be an important factor controlling proxy variations. Previous results from lacustrine sediments indicated a relationship with humidity conditions in the catchment. To rate how significant such weathering effects are for interpreting paleoclimate records, we performed an actualistic study of magnetite alteration in rock weathering in dependence of climatic conditions, in particular mean annual precipitation (MAP). Using basalts as a common rock type, we compared fresh rock and related weathered material at sites with different MAP and different mean annual temperature (MAT). The results show that alteration of magnetite is only slightly stronger in wetter climates, but surprisingly clearly stronger in colder climates at same MAP. The latter is possibly due to micro‐cracks formed through freezing and thawing that opens pathways for moisture and oxygen into particle interiors. Overall, the results suggest that climate‐dependent magnetite alteration during rock weathering in the catchment is unlikely a controlling factor of paleoclimate records. Rock magnetic variability of source rocks will mostly hide these effects. Key Points: Stronger alteration of magnetite during rock weathering in wetter climates is indicated, but is hidden by source rock heterogeneityAt equal humidity, magnetite alteration can be stronger in colder climates, possibly favored by frost‐induced micro‐cracksMagnetic records in sediment archives will likely not show humidity‐related magnetite alteration effects acquired during rock weathering [ABSTRACT FROM AUTHOR]

• A simple electrostatic attraction method synthesis Z-Scheme ternary heterojunction. • Formed Schottky junction make electrons and holes can be maximal separation. • Optimized degradation performance on MB and TC under visible-light irradiation. • Discussed the path of charge transfer and the mechanism of pollutant degradation. ga1 The discharge of industrial wastewater poses serious concerns to the environment and human health. Therefore, urgent development of simple and efficient catalysts for removal of pollutants is required. In this study, a novel ternary nanocomposite Ag/g-C 3 N 4 /LaFeO 3 (A/CN/LFO) was synthesized for the degradation of dye and pharmaceutical wastewater. The catalyst was prepared by decorating Ag nanoparticles (NPs) on g-C 3 N 4 /LaFeO 3 (CN/LFO) Z-scheme heterojunction and formation of Schottky junctions with LaFeO 3 (LFO) and g-C 3 N 4 (CN). The formed hybrid structure between metal and Z-scheme heterojunction induced directional transfer of electrons or holes from the Z-scheme heterojunction to metal, providing maximum separation between electrons and holes for more efficient redox reactions. Consequently, the ternary nanocomposite displayed optimized efficiencies toward the photocatalytic degradation of methylene blue (MB) and tetracycline hydrochloride (TC) under visible-light irradiation, estimated to 98.97% (90 min) and 94.93% (120 min), respectively. These values were almost 4.81 times and 3.88 times higher than those of pristine LaFeO 3 , respectively. The charge transfer mechanism and pollutant degradation pathway were also studied. The data revealed that Ag decorated Z-scheme heterojunction showed efficient light absorption and separation of photogenerated carriers, which might be useful for large-scale practical applications related to wastewater treatment and pollution control. [ABSTRACT FROM AUTHOR]

Abstract To quantify how urbanization induced long-term changes have altered the evolution of urban climate, a novel eco-hydrological diagnostic is introduced and applied globally, to a developing and a developed country (China and US-America). Urban areas are (i) geographically identified by remote sensing based nighttime light, (ii) physically embedded in state spaces spanned by suitable combinations of surface energy and water fluxes comprising the rainfall-runoff chain, and (iii) dynamically characterized by the time evolution of the surface fluxes at geographically fixed locations, analyzed as trajectories in state space, and interpreted by an attribution model separating anthropogenic from climate induced causes. The results describe the long term climatological settings of urban areas in a net radiation versus dryness diagram, while the attribution of change is diagnosed in a state space spanned by energy and water excess: (i) Cities in China are characterized by a bi-modal distribution separated by the boundary between water and energy-limited (northern and southern) regimes while US-American cities are assembling unimodally on this boundary, and globally the urbanized areas are also aligned along this boundary between water and energy-limited regimes. (ii) Attribution of eco-hydrological changes of urbanized regions to climate and human-induced causes shows also basic differences between the developing and developed country: urbanization in Chinese cities is characterized by a 'wet-gets-drier' and 'dry-gets-wetter' paradigm of the climate-induced contributions, due to which cities tend towards a unimodal state as it is observed for US-American urban areas. Finally, implications for large scale city planning are discussed in the outlook. Graphical abstract Unlabelled Image Highlights • Nighttime lighted urbanization is subjected to eco-hydrological analysis. • Urbanization shows differences between developing and developed countries. • Bi-modal and uni-modal distributions characterize Chinese and US-American cities. • Chinese cities follow climate induced 'wet-gets-drier' and 'dry-gets-wetter' changes. • Global urbanization develops towards uni-modality. [ABSTRACT FROM AUTHOR]

A number of studies have shown that added value is obtained by increasing the horizontal resolution of a regional climate model to capture additional fine-scale weather processes. However, the mechanisms leading to this added value are different over areas with complicated orographic features, such as the Tibetan Plateau (TP). To determine the role that horizontal resolution plays over the TP, a detailed comparison was made between the results from the REMO regional climate model at resolutions of 25 and 50 km for the period 1980-2007. The model was driven at the lateral boundaries by the European Centre for Medium-Range Weather Forecasts Interim Reanalysis data. The experiments differ only in representation of topography, all other land parameters (e.g., vegetation characteristics, soil texture) are the same. The results show that the high-resolution topography affects the regional air circulation near the ground surface around the edge of the TP, which leads to a redistribution of the transport of atmospheric water vapor, especially over the Brahmaputra and Irrawaddy valleys—the main water vapor paths for the southern TP—increasing the amount of atmospheric water vapor transported onto the TP by about 5%. This, in turn, significantly decreases the temperature at 2 m by > 1.5 °C in winter in the high-resolution simulation of the southern TP. The impact of topography on the 2 m temperature over the TP is therefore by influencing the transport of atmospheric water vapor in the main water vapor paths. [ABSTRACT FROM AUTHOR]

To enhance understanding of Earth's climate, numerical experiments are performed contrasting a retrograde and prograde rotating Earth using the Max Planck Institute Earth system model. The experiments show that the sense of rotation has relatively little impact on the globally and zonally averaged energy budgets but leads to large shifts in continental climates, patterns of precipitation, and regions of deep water formation. Changes in the zonal asymmetries of the continental climates are expected given ideas developed more than a hundred years ago. Unexpected was, however, the switch in the character of the European–African climate with that of the Americas, with a drying of the former and a greening of the latter. Also unexpected was a shift in the storm track activity from the oceans to the land in the Northern Hemisphere. The different patterns of storms and changes in the direction of the trades influence fresh water transport, which may underpin the change of the role of the North Atlantic and the Pacific in terms of deep water formation, overturning and northward oceanic heat transport. These changes greatly influence northern hemispheric climate and atmospheric heat transport by eddies in ways that appear energetically consistent with a southward shift of the zonally and annually averaged tropical rain bands. Differences between the zonally averaged energy budget and the rain band shifts leave the door open, however, for an important role for stationary eddies in determining the position of tropical rains. Changes in ocean biogeochemistry largely follow shifts in ocean circulation, but the emergence of a "super" oxygen minimum zone in the Indian Ocean is not expected. The upwelling of phosphate-enriched and nitrate-depleted water provokes a dominance of cyanobacteria over bulk phytoplankton over vast areas – a phenomenon not observed in the prograde model. What would the climate of Earth look like if it would rotate in the reversed (retrograde) direction? Which of the characteristic climate patterns in the ocean, atmosphere, or land that are observed in a present-day climate are the result of the direction of Earth's rotation? Is, for example, the structure of the oceanic meridional overturning circulation (MOC) a consequence of the interplay of basin location and rotation direction? In experiments with the Max Planck Institute Earth system model (MPI-ESM), we investigate the effects of a retrograde rotation in all aspects of the climate system. The expected consequences of a retrograde rotation are reversals of the zonal wind and ocean circulation patterns. These changes are associated with major shifts in the temperature and precipitation patterns. For example, the temperature gradient between Europe and eastern Siberia is reversed, and the Sahara greens, while large parts of the Americas become deserts. Interestingly, the Intertropical Convergence Zone (ITCZ) shifts southward and the modeled double ITCZ in the Pacific changes to a single ITCZ, a result of zonal asymmetries in the structure of the tropical circulation. One of the most prominent non-trivial effects of a retrograde rotation is a collapse of the Atlantic MOC, while a strong overturning cell emerges in the Pacific. This clearly shows that the position of the MOC is not controlled by the sizes of the basins or by mountain chains splitting the continents in unequal runoff basins but by the location of the basins relative to the dominant wind directions. As a consequence of the changes in the ocean circulation, a "super" oxygen minimum zone develops in the Indian Ocean leading to upwelling of phosphate-enriched and nitrate-depleted water. These conditions provoke a dominance of cyanobacteria over bulk phytoplankton over vast areas, a phenomenon not observed in the prograde model. [ABSTRACT FROM AUTHOR]

Analyses of precipitation (1961-2010) from 39 meteorological stations in the Tarim River Basin revealed a trend from dryer towards wetter conditions induced by an increase of the number of wet extremes. A first (1961-1986) and second (1987-2010) period are the basis for a dynamical analysis of changing drought and wetness extremes which are closely related to cyclonic activity over the European continent and circulation anomalies in the Northern Hemisphere mid-latitudes. Wave train, cyclone tracks, water flux and potential vorticity (PV) front analysis of the wet and dry months show the following result: (1) The extreme wet and dry cases in winter and summer are characterized by distinguished wave train patterns upstream of the Tarim River Basin. All wave trains originate in the Atlantic-European sector pointing towards wave train dynamics as one possible mechanism underlying the connection patterns observed. (2) The selected extreme cases show that exceptional precipitation events can be connected to characteristic cyclone tracks and a PV front in the upper troposphere even if cyclone tracks never cross the Tarim Basin. Extremely wet winters are characterized by cyclone tracks close to the western and northern boundary of the Tarim Basin whereas, during extremely dry winters, such cyclone tracks are absent. Wet summers are characterized by long-lived cyclonic anomalies at the north western corner of the Tarim River Basin [see also (3)]. During dry summers such anomalies are absent. (3) On a more local level the hydrological extreme events are linked to special dynamical structures of the upper tropospheric PV front. In winter strong (extreme) precipitation is connected to a strong non-linear wave development or a wave-breaking event over the Tarim River Basin. Together with non-linear wave development moisture and precipitation areas are advected towards the Tarim River Basin. In dry winters the upper tropospheric PV front is much more zonally oriented and wave-breaking is less frequent. Strong precipitation events are connected to strong breaking events and to the formation of long-lived nearly stationary cyclones over or north of the Tarim River Basin during extremely wet summer months. [ABSTRACT FROM AUTHOR]

Precipitation data between 1961 and 2010 from 39 meteorological stations in the Tarim River Basin are analyzed to classify and investigate hydrological drought and wetness conditions by using the standardized precipitation index (SPI). The leading time and spatial variability of hydrological drought has been investigated by applying a principal component analysis and Varimax rotation to the SPI on a time scale of 24 months. The results suggest that the western basin is characterized by a clear tendency towards wetter conditions after the middle of the 1980s, which results from an increase in the number of wet extremes and can be considered as a regime shift. Subdividing the period of analysis into two parts (1961-1986 and 1987-2010) this change can be clearly seen in a shift of the probability distribution function of precipitation events. Composite analyses of monthly mean geopotential height fields and wind fields of the ERA-40 data set show that enhanced wetness in the Tarim River Basin after the middle of 1980s is closely related to cyclonic anomalies on the European continent and circulation anomalies over mid-latitude of the Northern Hemisphere. Further correlation analysis between the principal components of SPI and large circulation indices shows that hydrological extremes in the Tarim River Basin correlate with indices related to the polar vortex and subtropical high. [ABSTRACT FROM AUTHOR]

Tropical SST anomalies are among the largest drivers of circulation regime changes on interannual time scales due to its characteristic heat capacity decay time scales. The circulation anomalies associated with extreme precipitation and the corresponding atmospheric response to SST anomalies are derived from ECMWF ERA-Interim reanalysis data by employing composite analysis and lagged maximum covariance analysis. Our results show that interannual variability of extreme winter precipitation in Southeast China is in close accordance with the interannual variability of total winter precipitation. Both are associated with similar abnormal circulation regimes, but for extreme precipitation events the circulation anomalies and moisture transport channels are significantly intensified. Two main moisture transport channels are captured: one extends from the North Indian Ocean through India and the Bay of Bengal to South China, and the other from the West Pacific Ocean through Maritime Continent and South China Sea towards South China, which are related to the preceding autumn SST patterns, El Niño and the Indian Ocean dipole (IOD), respectively. El Niño (La Niña) SST anomalies induce anomalous anticyclonic (cyclonic) circulation over Philippine Sea, which is favorable (unfavorable) to warm and humid air transport to South China from the tropical West Pacific by southwesterly (northeasterly) anomalies. Under these circulations, northeasterlies of East Asian Winter Monsoon are weakened (strengthened) resulting in extreme precipitation to be more (less) frequent in Southeast China. During the positive (negative) IOD phase, abundant (reduced) moisture transport to South China from tropical regions through India and Bay of Bengal is observed due to weakened (strengthened) Walker circulations and abnormal anticyclonic (cyclonic) circulation over India, leading to a higher (lower) likelihood for extreme precipitation events in Southeast China. The underlying physical mechanisms can be explained by a simplified one-dimensional vorticity equation (Sverdrup balance). [ABSTRACT FROM AUTHOR]

Over the Far East in summer, climate is strongly influenced by the fluctuating Western Pacific Subtropical High (WPSH), and strong precipitation is often associated with southeasterly low-level wind that brings moist air from the southern China seas. The WPSH intraseasonal variability is partly influenced by quasi-stationary wave-trains propagating eastwards from Europe across Asia along the two westerly jets: the Silk-Road wave-train along the Asian jet at midlatitudes and the polar wave-train along the sub-polar jet. In the unusual summer of 2010, northeast China experienced its worst seasonal flooding for a decade, triggered by unusually severe precipitation. That summer was also characterized by a record-breaking heat wave over eastern Europe and Russia, whose impact on the precipitation further east over China has been little explored. Here, we examine the role of the Silk-Road and polar wave-trains, and their impact on precipitation over northeast China throughout August 2010, using station precipitation data and re-analyses. We found that there is a strong link between the Silk-Road wave-train and extreme precipitation events. Forecasting such regional precipitation events at the monthly time-scale remains a big challenge for operational global prediction systems. In this study, we use simulations with the atmospheric model of the European Centre for Medium-range Weather Forecasts (ECMWF) to highlight the key role of the Silk-Road and polar wave-trains in modulating extreme precipitation over north and northeast China in August 2010. While the ensemble-mean of the forecasts fails to predict the pulses of the Silk-Road wave-train, some model members show a high spatial correlation in upper-level meridional winds with re-analyses. Similarly, there is high spatial correlation between model meridional winds and precipitation. These results highlight the importance of better representing the intraseasonal evolution of the Silk-Road wave-train in order to improve the monthly prediction of summer precipitation over the Far East. [ABSTRACT FROM AUTHOR]

Degree days are usually defined as the accumulated daily mean temperature varying with the base temperature, and are one of the most important indicators of climate changes. In this study, the present-day and projected changes of four degree days indices from daily mean surface air temperature output simulated by Max Planck Institute, Earth Systems Model of low resolution (MPI-ESM-LR) model are evaluated with the high resolution gridded-observation dataset and two modern reanalyses in China. During 1979-2005, the heating degree days (HDD) and the numbers of HDD (NHDD) have decreased for observation, reanalyses (ERA-Interim and NCEP/NCAR) and model simulations (historical and decadal experiments), consistent with the increasing cooling degree days (CDD) and the numbers of CDD (NCDD). These changes reflect the general warming in China during the past decades. In most cases, ERA-Interim is closer to observation than NCEP/NCAR and model simulations. There are discrepancies between observation, reanalyses and model simulations in the spatial patterns and regional means. The decadal hindcast/forecast simulation performance of MPI-ESM-LR produce warmer than the observed mean temperature in China during the entire period, and the hindcasts forecast a trend lower than the observed. Under different representative concentration pathway (RCP) emissions scenarios, HDD and NHDD show significant decreases, and CDD and NCDD consistently increase during 2006-2100 under RCP8.5, RCP4.5 and RCP2.6, especially before the mid-21 century. More pronounced changes occur under RCP8.5, which is associated with a high rate of radiative forcing. The 20th century runs reflect the sensitivity to the initial conditions, and the uncertainties in terms of the inter-ensemble are small, whereas the long-term trend is well represented with no differences among ensembles. [ABSTRACT FROM AUTHOR]

To complement geographical presentation of remote sensing vegetation information, the authors apply Budyko's physical state space diagram to analyze functional climate relations. As an example, the authors use Interim ECMWF Re-Analysis (ERA-Interim) global weather data to provide the statistics (1982-2006) of climate states in a two-dimensional state space spanned by water demand (net radiation N) versus water/energy limitation (dryness ratio D of net radiation over precipitation). Embedding remote sensing-based Global Inventory Modeling and Mapping Studies (GIMMS) data [normalized difference vegetation index (NDVI) > 0.1] shows the following results: (i) A bimodal frequency distribution of unit areas (pixels) is aligned near D ~ 1 but separated meridionally, associated with higher and lower net radiation. (ii) Vegetation states are represented as ( N, D, NDVI) triplets that reveal temperate and tropical forests crossing the border ( D ~ 1) separating energy- and water-limited climates but unexpectedly show that they also exist in marginal regions (few pixels) of large dryness. (iii) Interannual variability of dryness is lowest where the largest climate mean NDVI values of greenness (forests) occur. The authors conclude that the combined ( N, D, NDVI) analysis based on climate means has shown that tropical and temperate forests (NDVI > 0.6) are (i) not restricted to the energy-limited domain D < 1 (extending into the water-limited surface climate regime) and (ii) associated with low interannual variability of dryness. Thus, measures of interannual variability may be included in Budyko's classical framework of geobotanic analysis of surface climates. [ABSTRACT FROM AUTHOR]

On the basis of daily observations of 39 meteorological stations in the Tarim River Basin, the variability of drought and wetness has been analysed using the standardized precipitation-evapotranspiration index (SPEI, 1961-2010). The result shows an increasing trend in annual mean SPEI with a significant change in 1986. Although the frequency of moderate and severe droughts decreased after the change, the frequency of extreme drought events increased slightly. But different categories of wetness show a consistent increase in frequency. The return periods of drought and wetness prolonged and shortened, respectively, after 1986. Furthermore, composites of geopotential height and water vapour flux fields at 500 hPa are analyzed for extreme wet and dry months of the warm season (May to October) as well as for the warm seasons of the periods 1961 to 1986 and 1987 to 2010. The difference between composites of extreme wet and dry shows that the water vapour supply during wet events can be related to transports from the Arabian Sea and the Bay of Bengal. The midlatitude atmospheric circulation plays an important role by transporting moisture from the east into the Tarim River Basin; this is the main reason of the wetter condition in warm seasons after 1986 in the study region. [ABSTRACT FROM AUTHOR]

ABSTRACT Climate warming on the Tibetan Plateau ( TP) potentially influences many climate parameters other than temperature including wind speed, cloudiness and precipitation. Temporal trends of surface wind speed at 71 stations above 2000 m above sea level in the TP are examined during 1980-2005. To uncover causes of observed trends in wind speed, relationships with surface temperature, a TP index and sunshine duration are also analysed. The TP index is calculated as the accumulated 500 hPa geopotential height above 5000 m over the region of 30°N-40°N, 75°E-105°E from NCEP/ NCAR reanalysis. The annual mean wind speed patterns during 1980-2005 are similar to those in different seasons, with higher wind speeds in the northern and western parts of the TP. Highest mean wind speeds occur in spring and lowest in autumn. During 1980-2005, annual and seasonal mean wind speeds show statistically decreasing trends at most stations. The mean trend magnitude for annual mean wind speed is −0.24 m s−1 decade−1, with the maximum decline in spring (−0.29 m s−1 decade−1) and minimum in autumn (−0.19 m s−1 decade−1). Both annually and in different seasons, wind speed is significantly negatively correlated with mean temperature, minimum temperature, maximum temperature, and the TP index, but significantly positively correlated with sunshine duration. Wind speed trends fail to show a simple elevation dependency but speeds are positively correlated with meridional surface temperature/pressure gradients. Warming in the TP may weaken the latitudinal gradients of both regional temperature and surface pressure, thus altering the regional atmospheric circulation and accounting in part for the observed decline of wind speed. [ABSTRACT FROM AUTHOR]

Ground-based GPS and weather stations time series for the period 2010-2012 of precipitable water vapor (PWV), relative humidity (RH), and surface temperature ( T) of half-hourly resolution are analyzed to demonstrate their value for dynamical analyses and weather forecasting. Three sample stations in the USA from the SoumiNet network are considered, which have rather continuous data for the last 3 years and a few missing values. Results for the three stations reveal the following features: (1) PWV time behavior is dominated by the annual cycle superimposed on high-frequency fluctuations with missing daily cycle, indicating a prevailing large-scale transport source of precipitable water at these sites; (2) RH is characterized by the daily cycle and high-frequency variability, while the annual cycle is missing; (3) T mainly varies following the annual and diurnal cycles; and (4) all variables show similar scaling properties of their variance spectra, S( f) ∼ f, with a high-frequency regime of red noise type scaling ( β ∼ 2) up to a day and long-term persistence beyond a week ( β ∼ 0.5), with a week-long frequency interval of transition. Detrended fluctuation analysis of relative humidity indicates a clear long-term persistence scaling covering more than three decades. Implications of these findings on weather forecasting and climate modeling are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Based on daily maximum, minimum and mean surface air temperature from National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis (NCEP/NCAR) and European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses, the distributions of twenty temperature indices are examined in China during 1958–2011. ECMWF includes ERA-40 for the period 1958–2001 and ERA-Interim during 2002–2011. The consistency and discrepancy of extreme indices between reanalyses and observations (303 stations) are assessed. In most cases, temperature indices between NCEP/NCAR and ECMWF have good agreements. For both reanalysis, cold days/nights have decreased, while warm days/nights have increased since 1980. Temperatures of the coldest days/nights and warmest days/nights significantly increase over the entire China, and the diurnal temperature range demonstrates slight variations; the amounts of growing season length, and summer/tropical days have increased, consistent with the decrease in numbers of frost/ice days. Furthermore, the persistence of heat wave duration and warm spell days has increased and consecutive frost days have reduced. Meanwhile, consecutive frost days, cold wave duration and cold spell days from NCEP/NCAR have decreased and consecutive frost days have increased, while these indices from ECMWF turn to the opposite directions. Compared with observations, temperature extremes from two reanalyses have small relative bias and the root mean squared errors, while correlation coefficients are positively high. These suggest that both reanalyses can reproduce the variability of temperature extremes obtained from observations, and can be applied to investigate climate extremes to some extent, although the biases exist due to the assimilation differences. [Copyright &y& Elsevier]

Precipitation maxima in global climate model (GCM) simulations are compared with observations in terms of resolution dependence and climate change. The analysis shows the following results: (i) the observed scaling law relating precipitation maxima to duration is basically reproduced but exhibits resolution dependence, (ii) the intensity of precipitation extremes is up to one order of magnitude smaller in the model data, and (iii) the increase of precipitation maxima on short time scales in the warmer climate simulations [representative concentration pathway 8.5 (RCP8.5)] vanishes for monthly time scales. [ABSTRACT FROM AUTHOR]

In the present paper the effect of an abrupt change of the atmospheric radiative forcing is investigated by means of a global climate model that includes a mixed layer ocean. In assessing if, under such a change, the model response has a bifurcation point, the steady solution is studied for a sudden decrease of CO concentration from its actual value. It is found that there is a critical threshold for CO content below which the model ends up to a snowball Earth. It occurs for a few percentage changes of CO concentration around the threshold because the model strongly depends on the relationship among atmospheric temperature, water vapor content and the sudden ice-albedo feedback activation, even in the subtropical regions. Moreover, results suggest that the transition to ice-covered Earth is clearly favoured when Q-flux corrections (i.e. the parameterization of ocean heat transports) are removed. [ABSTRACT FROM AUTHOR]

Several studies show that the anomalous long-lasting Russian heat wave during the summer of 2010, linked to a long-persistent blocking high, appears mainly as a result of natural atmospheric variability. This study analyzes the large-scale flow structure based on the ECMWF Re-Analysis Interim (ERA-Interim) data (1989-2010). The anomalous long-lasting blocking high over western Russia including the heat wave occurs as an overlay of a set of anticyclonic contributions on different time scales. (i) A regime change in ENSO toward La Niña modulates the quasi-stationary wave structure in the boreal summer hemisphere supporting the eastern European blocking. The polar Arctic dipole mode is enhanced and shows a projection on the mean blocking high. (ii) Together with the quasi-stationary wave anomaly, the transient eddies maintain the long-lasting blocking. (iii) Three different pathways of wave action are identified on the intermediate time scale (~10-60 days). One pathway commences over the eastern North Pacific and includes the polar Arctic region; another one runs more southward and crossing the North Atlantic, continues to eastern Europe; a third pathway southeast of the blocking high describes the downstream development over South Asia. [ABSTRACT FROM AUTHOR]

Daily temperature records including daily minimum, maximum, and average temperature from 190 meteorological stations over China during 1951-2000 are analyzed from two perspectives: (a) long-term persistence in direction of time varies, and (b) standard deviation in direction of amplitude varies. By employing the detrended fluctuation analysis (DFA), we find all the temperature records are long-term correlated, while the exponent α obtained from DFA varies from different districts of China due to different climate conditions, such as the southwest monsoon, subtropical high, northeast cold vortex, and the Tibetan plateau, etc. After we take the standard deviation into account, a new index χ = α × σ, which has been proposed recently, can be obtained. By further rescaling it as $$ \chi = \overline \chi - {{1} \left/ {5} \right.} \times {\sigma_{{\overline \chi }}} $$, we find an obvious change of χ for these three kinds of time series, from which the whole China can be divided into two groups, which are comparatively consistent with dry/wet distributions in the south-north areas over China. [ABSTRACT FROM AUTHOR]