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The roles of moisture sources and transport in intraseasonal precipitation variabilities during the preflood season over South China are complex and different. In this paper, ERA‐Interim reanalysis data that were collected four times daily from 1979 to 2017 are used to analyse the variation and influence of moisture transport in intraseasonal precipitation during the preflood season over South China. Using the Hybrid Single‐Particle Lagrangian Integrated Trajectory model, fixed atmospheric moisture sources are defined: land area source (LD source), Indian Ocean source (IO source), Pacific Ocean source (PO source), South China Sea source (SCS source), and South China source (SC source). Sea source moisture transport accounts for more than 75% of the total precipitation during the preflood season, which is the most important moisture source in South China. For April, southeasterly moisture transport, which includes PO source and SCS source moisture transports, is the major moisture transport over South China. Then, the IO source and SCS source precipitation increased significantly during May. During June, the IO source precipitation accounted for 43.75% of the total precipitation, thus dominating precipitation over South China. In addition, there is a significant difference in the interdecadal variation in the preflood season precipitation before and after the Indian summer monsoon onset. Before the Indian summer monsoon onset, the land‐sea thermal contrast decreased, which led to a significant interdecadal reduction in the IO source, PO source, and SCS source moisture transports. After the Indian summer monsoon onset, the increase in IO source moisture transport is the primary cause of the interdecadal increase in precipitation over South China. [ABSTRACT FROM AUTHOR]

In a previous study by the authors, a regional climate model (hereafter the RCM) developed to study the summer monsoon over South China (SC) and the South China Sea (SCS) has been tested and found to be able to simulate to a large extent the precipitation over this region for the months of May and June. To examine the interannual variability of the summer monsoon here, it is necessary to establish a model climatology to serve as a comparison and to reduce or even remove any systematic model biases. This paper presents the analyses of such a 10-year climatology (1991-2000). The model was initialized on 1 April and integrated up to the end of June for the ten years. The initial atmospheric conditions and lateral boundary data used in this study are from the European Centre for Medium-range Weather Forecasts '40-year' reanalyses. The RCM can reproduce well the main features of the monsoon circulation and vertical structure of the atmosphere. The RCM can simulate the intensification and northwestward displacement of the south Asian upper anticyclones from May to June, as well as the low-level moisture transport from the Bay of Bengal to SC. In the simulation, the average SCS summer monsoon onset occurs in the fourth pentad of May, which is consistent with the results from previous observational research. In addition, the RCM can reproduce the main characteristics of the onset such as the change of the low-level zonal flow from easterly to westerly as well as the rapid increase in daily precipitation. The SC and SCS precipitation anomalies have the correct sign in almost all the years. The shortcomings of the model simulation include an under-prediction of the strength of the subtropical high over the Northwest Pacific and the moisture transport from the Bay of Bengal to the Indochina Peninsula (IC) and SCS. A cold bias in surface air temperature is also observed, with the 10-year mean biases of the simulated surface air temperature over SC, SCS and IC in May and June being about −2.1 °C, −2.4 °C and −1.4 °C respectively. The 10-year mean biases of the simulated daily precipitation rate over SC, SCS and IC are about 2.0, −3.8 and 3.5 mm d−1 respectively. Copyright © 2005 Royal Meteorological Society. [ABSTRACT FROM AUTHOR]

The first rainy season (April–May–June) extreme precipitation events over South China tend to frequently occur in specific hotspots, resulting in a great threat to local society and economy. Abundant moisture supply is essential to precipitation formation. In this study, we employ the FLEXPART model to investigate the geographical moisture sources for extreme precipitation events in three hotspots of Guangdong from west to east (termed as Area‐A, B, and C). During both the periods before and after the onset of the South China Sea Summer Monsoon (hereafter SCSSM), the moisture contributions of ocean regions are larger than that of land regions for all the hotspots, but the main moisture source regions are different. Before the onset of SCSSM, the main source regions are South China Sea and Southeastern Asia, which contribute 36.50 and 31.79% to Area‐A, 35.85 and 27.83% to Area‐B, while 42.27 and 23.81% to Area‐C, respectively. After the onset of SCSSM, the contribution of moisture from Indian Ocean increases a lot. Thus, the main source regions are Indian Ocean, Southeastern Asia and South China Sea, which contribute 31.52, 24.58 and 18.13% to Area‐A, 29.21, 21.82 and 14.99% to Area‐B, 26.62, 20.70%, and 28.19% to Area‐C, respectively. Among the three hotspots, the contribution of ocean regions for Area‐C is the largest. Southeastern Asia is the main land contributor before and after the onset of SCSSM for all the hotspots. This study implies the important role of both ocean and land moisture sources on extreme precipitation variations over South China. [ABSTRACT FROM AUTHOR]

ABSTRACT Climate is a primary driver for extreme rainfall and flood events. In this paper, the temporally changing flood risk associated with the annual maximum 30-day rainfall (30-day AMR) and the annual maximum daily inflow ( AMDI) related to the Xidayang Reservoir catchment is analysed from a climatic context. This is the largest catchment in Daqing River Basin in North China and is highly prone to floods related to the East Asian summer monsoon. Two climate factors, the average May-June-July sea surface temperature anomalies in areas of the northern Indian Ocean and western Pacific Ocean, are identified. They show a high negative correlation with the AMDI and 30-day AMR. Bayesian nonstationary models are then developed for the AMDI and 30-day AMR using the climate predictors identified as covariates. We compared three types of models of AMDI and 30-day AMR: (1) time-invariant, (2) linear temporal trend and (3) climate informed, and found that the climate-informed models exhibit the best performance according to Deviance Information Criterion (DIC) and 90th percentile Bayesian coverage rate for both AMDI and 30-day AMR. A significant decreasing trend is identified in the AMDI and the 30-day AMR, which is found to be associated with the climate predictors. Leave one out cross validation (LOOCV) is used to demonstrate that these models have decent skill in predicting year-to-year variability in flood risk. This can help to provide flood/rainfall dynamic management measures for reservoirs in Daqing River Basin using information from before the beginning of monsoon season, thus facilitating adaptation to a changing climate. [ABSTRACT FROM AUTHOR]

The East Asian summer monsoon (EASM) is unique among monsoon systems that it features meridional evolution of the summer monsoon. In this study, we evaluate the performances of a Variable‐Resolution Community Earth System Model (VR‐CESM) regionally refined over eastern China (14 km) in reproducing the seasonal evolution of EASM precipitation over China. Compared with reference datasets, VR‐CESM shows better performance than the corresponding globally uniform coarse‐resolution model CESM (quasi‐uniform 1°), especially over western China where complex local topography exists. The northward monsoon migration is closely related to low‐level southerly flows and vertical moisture advection, which are more reasonably simulated in VR‐CESM. The four critical timings of the EASM (monsoon onset, withdrawal, peak, and duration) are also better captured in VR‐CESM than in CESM. The corresponding spatial Pearson correlation coefficients of the four critical timings with respect to reference datasets are about 0.1 higher in VR‐CESM than those in CESM. Both models are most accurate in simulating monsoon onset and least accurate at simulating the monsoon peak. The overestimated zonal thermal contrast in CESM is responsible for the earlier monsoon onset and excessive precipitation in September over the Yangtze River valley. Finer resolution in VR‐CESM, especially over the Tibetan Plateau (TP), appears to be a main factor in simulating better zonal thermal contrast and seasonal evolution of the EASM. [ABSTRACT FROM AUTHOR]

A heavy rainfall trajectory (HRT) is defined as the trajectory formed by the movement of the rainstorm centre of a heavy rainfall event over time. Based on this definition, the dispersion degree (DD) of HRTs is applied based on the Euclidean distance and an empirical orthogonal function (EOF) to quantify the spatiotemporal distribution and evolution characteristics of HRTs in China. The results show that (a) the spatial distribution and length of HRTs in China have distinct geographical and seasonal characteristics, which are strongly influenced by the East Asian summer monsoon. (b) From southeast China to northwest China, the DDs increased to 8 and the length of HRTs decreased by 53,925 m. (c) According to EOF analysis, the direction angle change of northeast‐oriented HRTs shows a significant negative trend across the country, while those of southeast‐, southwest‐ and northwest‐oriented HRTs show a significant positive trend. From 2008 to 2019, HRTs flattened in the northeast and southwest directions, while HRTs steepened in the southeast and northwest directions. This research provides certain scientific guidance for the prevention and mitigation of regional disasters and provides necessary theoretical support for the changing patterns of the climate system under the impact of climate change. [ABSTRACT FROM AUTHOR]

This study investigates inter‐model spreading of changes in East Asian winter monsoon circulation and the underlying reasons under 1.5 and 2.0°C global warming for Representative Concentration Pathway 8.5. Results show that the spatial patterns of multi‐model ensemble and inter‐model spreading of changes in 850‐hPa zonal and meridional winds over East Asia are similar under the two global warming targets. The multi‐model ensemble changes in 850‐hPa meridional wind (V850) over southern China are near zero under the two targets. Meanwhile, the V850 changes over southern China exhibit large inter‐model spreading, which is closely related to those of regional differences in sea surface temperature changes (DSSTC) in the tropical Pacific. Models with positive V850 anomalies over southern China tend to project weak (strong) surface warming in the western North Pacific (South China Sea and the equatorial central and eastern Pacific). Such a configuration results in decreased precipitation over the east of the Philippines and hence an anomalous lower‐level high to its northwest. Accordingly, southwesterly anomalies prevail over southern China. The southwesterly anomalies are further enhanced by related positive feedback processes. Models with negative V850 anomalies tend to project strong (weak) surface warming in the western North Pacific (South China Sea). The projected surface warming in the equatorial central and eastern Pacific is also strong, but weaker than that of models with positive V850 anomalies. Therefore, the induced precipitation and circulation changes over the East Asia–western North Pacific are basically opposite to those described above. Besides, the inter‐model spreading of V850 changes over southern China decrease by about 36.2% from 1.5 to 2.0°C global warming, which can be partly attributed to the decrease in the inter‐model spreading of DSSTC in the tropical Pacific. Numerical experiments confirm the role of the sea surface temperature changes in the tropical Pacific. [ABSTRACT FROM AUTHOR]

The monsoon development in the early rainy season in East Asia is analysed by the evolution of daily weather types (WTs). The WTs are classified by a k‐means clustering analysis based on 850 hPa winds from April 1 to July 31 in the 40‐year period of 1979–2018. Five WTs are identified, typifying the progression of weather regimes in the monsoonal evolution. WTs 1 and 2, with easterly winds in the South China Sea (SCS), occurs mostly in April and early May, corresponding to typical WTs before the SCS monsoon onset. In WT3, winds in the SCS turns westerly, and a rain band emerges in South China, extending east‐northeastward to the Pacific Ocean south of Japan, which signifies the May–June Mei‐yu in South China. Then, with the rain band moved to Yangtze River Valley (YRV) in WT4, this WT corresponds to the June–July Mei‐Yu in central and eastern China along the YRV. Finally, WT5 occurs more frequently towards the end of July, and corresponds to the post‐Mei‐Yu WT, indicating the ending of the early summer rainfall season in East Asia. The evolution of the WTs is gradual but intermittent, representing the weather‐within‐climate information. Each WT likely persists to itself. But WT1 and WT2 also progress to each other. The long persistence of WT3 and WT4 up to several weeks indicates the quasi‐stationary Mei‐Yu in South China and the YRV, respectively. The year‐to‐year variability of the WTs is also evident in the WTs. The El Niño–Southern Oscillation (ENSO) impact on the precipitation in the East Asian region is analysed for three types of ENSO: Eastern Pacific, Central Pacific, and mixed El Niño and La Niña. The seasonal mean precipitation anomalies can be interpreted by the frequencies of the daily WTs under different ENSO conditions. [ABSTRACT FROM AUTHOR]

The thermal forcing of the Tibet Plateau (TP) causes circulation anomalies that may affect the East Asian monsoon. Hence, summer precipitation in China has a close relation to the previous heat source over TP. The saturation of the atmosphere is the precondition of precipitation, so variations of vapour and temperature adjust the generation of precipitation synergistically. The heating of TP exerts impacts on summer precipitation in China, essentially, through modulating vapour and temperature. The goal of this study is to identify whether the variations of temperature or vapour dominate in the end. Besides, according to the heating characteristics over TP, a more accurate area of spring (March–May) heat source is chosen to indicate the midsummer (July) precipitation in China. The configuration of contributions of temperature and vapour can be divided into two cases. One is that vapour and temperature both increase or decrease, so they play inverse roles. It is easy to find the dominant element in this circumstance. The other is that vapour and temperature have concurrent effects. In this case, their significances need to be further compared. The method based on the linkage of the precipitation and relative humidity is used to quantitatively compare the effects of temperature and vapour. The results are robust and can complement the qualitative analysis with circulations and temperature. In years that there is intense heating on west TP, the Yangtze River basin (YZRB) is controlled by more vapour transport from oceans. The downstream of the Yellow River basin (YLRB) is affected by the dry and cold northerly winds. Dominance analysis shows that vapour general plays a more important role in two major river basins. Maybe not exactly coincide with someone's envision, not all the places are dominated by the vapour. Around northeast China, temperature contributes little more than vapour. [ABSTRACT FROM AUTHOR]

Bias‐corrected monthly precipitation and surface temperature datasets are constructed for the monsoon transitional zone (MTZ) in China during 1965–2100 based on 21 coupled climate models from phase 6 of the Coupled Model Intercomparison Project (CMIP6) using the equi‐ratio and equidistant cumulative distribution function quantile‐based mapping methods (equi‐ratio cumulative distribution function [ERCDF] and equidistant cumulative distribution function [EDCDF]), respectively. The efficiencies of the two methods are verified via cross‐validation by the jack‐knife method, and the biases are remarkably reduced compared to those of the raw model outputs. Then, the bias‐corrected model outputs are applied to future projections of precipitation, surface temperatures and drought events under the medium (SSP2‐4.5) and high (SSP5‐8.5) shared socioeconomic pathway scenarios. The obtained results present pronounced increases in both the projected annual mean precipitation and temperature fields for the model ensemble mean. In accompany, the MTZ is predicted to become drier in the three future periods; this result was attributed to the dramatic increases in semiarid events and to the decreases in humid events. The drought tension showed more rapid development under SSP585 than under the other scenario, with comparable occurrence frequencies of relatively wet and dry events in the long‐term period, posing a serious threat to regional sustainable development. [ABSTRACT FROM AUTHOR]

The different impacts of El Niño on the East Asian summer precipitation (EASP) between its developing and decaying stages are investigated in observations. The EASP responses are almost opposite between the two stages, with an anomalous wet (dry) in Southeast China and an anomalous dry (wet) in North China in the developing (decaying) summer. In the developing summer, El Niño influence on EASP is through its direct impact of the sea surface temperature (SST) anomaly in the tropical Pacific, which induces heating perturbations that excite an upper‐level zonally propagating wave train in mid‐latitude and a lower‐level meridional wave train along the East Asian coast. In contrast, in the decaying summer, El Niño affects EASP through the El Niño‐generated SST anomalies outside the equatorial Pacific, which are combined to produce an uplift of geopotential height around the upper‐level tropics and a lower‐level Pacific‐Japan (PJ) wave train. [ABSTRACT FROM AUTHOR]

The relationship of the tropical Indo‐Pacific upper ocean heat content (HC) and the South China Sea (SCS) summer monsoon (SCSSM) onset during 1980–2020 was investigated. It was found that when HC anomalies in the preceding winter–spring are positive (negative) in the eastern Indian–western Pacific Ocean or negative (positive) in the southwestern Indian Ocean and eastern Pacific Ocean, SCSSM onset is usually early (late). Empirical orthogonal function (EOF) analysis suggested that the primary EOF modes of HC anomaly in both tropical Pacific and Indian Oceans are associated with El Niño–Southern Oscillation (ENSO). It is through modulating the westerly over the north Indian Ocean–SCS and the western north Pacific subtropical high (WNPSH) via the Walker circulation over the Indo‐Pacific basin, monsoon circulation in the Indian Ocean that the ENSO related Indo‐Pacific HC variation connects with the SCSSM onset. Both the second EOF modes for the tropical Pacific and Indian Ocean also show significant correlations with the SCSSM onset. The former related vertical motion over the SCS–far northwestern Pacific can influence the WNPSH and convection, thus occurrence of the SCSSM. The latter represents the intrinsic Indian Ocean HC variability; the air temperature variation associated with it can modulate the atmospheric circulation in the Indian Ocean–SCS through thermal wind balance, and thus the SCSSM onset by acting on the westerly over the SCS and the WNPSH. A western Pacific index and an Indian Ocean dipole index were defined to represent the leading HC modes in the tropical Pacific and Indian Ocean, respectively. A binary linear regression model was constructed using these two indices to improve SCSSM onset prediction. [ABSTRACT FROM AUTHOR]

We quantitatively distinguish the fast and slow responses of the East Asian summer monsoon (EASM) to aerosol forcing using the outputs from 16 Coupled Model Intercomparison Project Phase 5 (CMIP5) models. The mechanism of the EASM change due to aerosol forcing is then evaluated from the perspective of upper‐tropospheric temperature change. The results show that aerosol forcing leads to the weakening of the EASM circulation and decreases in precipitation. The aerosol‐induced fast atmospheric response dominates the weakening of EASM and the decreased precipitation over the eastern China. In the fast response, upper‐tropospheric cooling in the mid‐latitudes of East Asia during summer changes the circulation structure, thereby causing the weakening of the EASM. The formation of upper‐tropospheric cooling is closely related to the eastward propagation of atmospheric cooling caused by aerosol forcing in Europe and the resulting change in local meridional heat transport. The slow ocean‐mediated response to aerosol forcing partially offsets the weakening of the EASM over the eastern China in the fast response. In the slow response, southwesterly wind is enhanced and precipitation is increased over the eastern China, while southwesterly wind is weakened over the northwestern Pacific and the South China Sea, which dominates the decrease in precipitation over the oceans. The aerosol‐induced changes of land–sea thermal contrasts further confirm that the decrease of upper‐tropospheric land–sea thermal contrasts over East Asia in the fast response plays a key role in driving the weakening of the EASM. [ABSTRACT FROM AUTHOR]

A regional Climate‐Weather Research and Forecasting (CWRF) model with a 30‐km horizontal resolution was applied to simulate the East Asian summer monsoon (EASM) and climate in China from 1980 to 2016. As compared with observations and reanalysis data, the model can reasonably reproduce the spatial distributions of the climatological mean atmospheric circulation and water vapour transport in East Asia, as well as the seasonal advance and retreat of EASM and rain bands. The correlation coefficient between the EASM circulation index in the simulation and reanalysis is.97. The model can well represent the geographic distributions of summer mean temperature and precipitation over most of China. However, model biases still exist, in particular the skill in the Yangtze–Huaihe River basin is relatively low. The simulated climatological mean temperature and precipitation deviations from observations may be related to the model's systematic circulation biases, with a thicker lower troposphere (i.e., higher temperature between 500 and 1,000 hPa) over most of China (except for the south and southwest) and a thinner one over the coastal oceans in summertime. Compared with the reanalysis, the model overestimates the land‐ocean thermal contrast, which causes the South Asian High shifted to the north and east, as well as the subtropical high and tropical convective activity located further north and persisted longer. Consequently, more water vapour transports northward, leading to more precipitation over North China–Northeast China and less precipitation over the Yangtze and Huaihe River basin. Therefore, the enhanced land‐ocean thermal contrast may be a major factor for the stronger EASM in the model, and corresponding precipitation and temperature biases in China. This analysis provides important information for further improving model performance in EASM simulation. [ABSTRACT FROM AUTHOR]

Previous studies suggested that sea surface temperature (SST) anomalies in the tropical central‐eastern Pacific (TCEP) and tropical Northern Atlantic (TNA) both have significant impacts on the inter‐annual variation of precipitation over the monsoon transitional zone (MTZ) in China during August–September. This study further reveals that the relationship between TCEP (TNA) SST and MTZ precipitation during August–September is strongly modulated by the sign of the TNA (TCEP) SST. When TCEP and TNA SST anomalies have the same sign, connections of the TCEP and TNA SST with the MTZ precipitation are unclear. In contrast, TCEP and TNA SST changes both have significant relation with the MTZ precipitation when they have the opposite sign. During the same‐sign years, the anticyclonic (cyclonic) anomaly over the western North Pacific generated by the TCEP SST cooling (warming) is weakened by the cyclonic (anticyclonic) anomaly triggered by the TNA SST cooling (warming). Thus, connections of the MTZ precipitation with the TCEP and TNA SST are weak. However, during the opposite‐sign years, the anticyclonic anomalies over the western North Pacific generated by the TCEP SST anomalies have a constructive superposition on those induced by the TNA SST changes. As such, connections of the TCEP and TNA SST with the MTZ precipitation variation are significant. Further analysis shows that the prediction skill of precipitation over the MTZ is enhanced if taking both the TCEP and TNA SST signals into account. [ABSTRACT FROM AUTHOR]

The relationship between the South China Sea summermonsoon (SCSSM) onset and the subsequent subtropical East Asian monsoon rainfall from May to September (SEAMR) is investigated. The SCSSM onset is found to have a significant positive correlation with the SEAMR stretching from the lower reaches of the Yangtze River valley (LYR) to the southern Japan; e.g. the early onset of the SCSSM tends to be succeeded by less SEAMR, whereas the late onset is likely to be followed by more SEAMR. The positive relationship between the SCSSM onset and the SEAMR is directly controlled by the persistent western North Pacific anti-cyclonic/cyclonic (WNPAC/WNPC) circulation anomaly from boreal spring to summer. The persistence of the large-scale circulation anomalies are accompanied by the decaying phase of El Niño (La Niña) with the pronounced sea-surface temperature anomalies (SSTA) over the tropical Indian Ocean (IO), the western North Pacific and the topical central and eastern Pacific Ocean (PO), respectively. Further numerical experiments indicate that the topical IO SSTA governs the positive relationship between the SCSSM onset and the subsequent SEAMR. On one hand, the wavelength of the Kevin-wave response to tropical IO SSTA forcing is three times that of the Rossby-wave response to the western North Pacific SSTA forcing. The Kevin-wave response directly influences the low level circulation anomalies field throughout the South China Sea region, determining the onset date of the SCSSM. On the other hand, the horizontal wind shear that induced by the persistent Kevin-wave response would also maintain theWNPAC/WNPC and further control the SEAMR from May to September. Thus, it is the topical IO SSTA forcing that consolidates the positive relationship between the SCSSM onset and the SEAMR. [ABSTRACT FROM AUTHOR]

ABSTRACT Daily rainfall data from 485 stations in China over the period 1961-2006 are used to examine changes in seasonal extreme rainfall. We focus on the temporal changes in their distribution, together with examination of the dependence of seasonal extreme rainfall on elevation. The validity of the stationarity assumption is investigated by testing for nonstationarities in the form of abrupt and slowly varying changes. The nonparametric Pettitt test is used to detect change points in the mean and variance of the rainfall distribution, while the presence of monotonic trends and trend magnitude is tested using Mann-Kendall test and Sen's slope estimator. Violation of the stationarity assumption is mostly associated with abrupt rather than gradual changes, and monotonic trends are generally not statistically significant. Most of the change points occurred in the 1980s, when China underwent a socioeconomic development. Extreme rainfall in autumn (spring and winter) points to a decreasing (increasing) tendency over the majority of the country, while summer extreme rainfall exhibits a 'dipole-like' structure, with an overall tendency towards increasing trends in the south and decreasing in the north. The parameters of the Generalized Extreme Value (GEV) distribution are used to examine the dependence of extreme rainfall on elevation. The location and scale parameters are negatively correlated with elevation, while orography does not appear to be an important control on the shape parameter. The dependence of GEV parameters on elevation is more pronounced in northern rather than southern China. We also investigated the relation between summer extreme rainfall and climate variability, focusing on the East Asia Summer Monsoon (EASM) index. EASM is negatively (positively) correlated with summer extreme rainfall over South (North) China. Considering the weakening trend of EASM in recent years, there is a potential water shortage in the North China Plain and increasing flood risk in the south. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The time-lagged effect of summer soil moisture (SM) on ensuing winter climate in eastern China is examined. The East Asian winter monsoon (EAWM) in early winter (November) and associated air temperature over eastern China are shown to significantly correlate with the previous summer (June-August) SM in eastern China with a center located at the lower reaches of the Yellow River (LRYR). The positive anomalies of summer SM, persisting for a few months, may act as a buffer to defer the ground cooling of eastern China in early winter mainly through modulating thermal capacity. And the warmer ground of eastern China could lead to a warmer air temperature above the ground through direct land-air interactions and through indirectly adjusting the EAWM which is sensitive to the land-sea thermal contrast. These results provide an empirical predictor for the EAWM and for the variability of air temperature over eastern China in early winter. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The interannual variations of the early summer South China monsoon rainfall (SCMR) in relation to different Pacific Decadal Oscillation (PDO) backgrounds are examined using station rainfall data and the European Centre for Medium-range Weather Forecasts (ECMWF) 40-year reanalysis (ERA-40) data. The objective of this study is to investigate the atmospheric circulation patterns responsible for such variations, thereby understanding the interdecadal modulation and the cause for the extreme wet and dry SCMR. The interannual SCMR variance shows an interdecadal change before and after the late 1970s, with significant differences in sea-surface temperature (SST) and atmospheric circulation anomalies between the negative (1958-1976) and positive (1980-1998) PDO epochs. The dominant atmospheric teleconnection patterns associated with extreme wet and dry SCMR are remarkably different in these two epochs. During 1958-1976, an anomalous wet (dry) SCMR is characterized by a significantly anomalous anticyclone (cyclone) over the South China Sea (SCS) and western Pacific in the lower troposphere in the form of a meridional wave-like coupling along the coast of western North Pacific in the early summer, and preceded by a monopole circulation anomaly over the Ural Mountain in the preceding winter. During 1980-1998, however, an anomalous wet (dry) SCMR features a relatively weak anomalous anticyclone (cyclone) over the SCS in the low level without a significantly meridional juxtaposition of anomalous circulations in the early summer, and it follows a remarkable coherent long wave train pattern in middle-high latitudes in the preceding winter. Such interdecadal differences in anomalous circulation structures suggest that the relative roles of internal atmospheric variability and external forcing may be different from different epochs. But for both epochs, the circulation anomaly over the Ural Mountain shows a highly negative correlation with anomalous SCMR, suggesting that the winter circulation anomaly around the Ural Mountain is of great significance for improving the seasonal prediction of SCMR. Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The article discusses the reconstruction of the Palmer Drought Severity Index (PDSI) for the Guiqing Mountain area in China. It discusses the analysis of tree rings of Pinus tabulaeformis in the reconstruction. It also discusses the linkages of the reconstructed droughts with the Indian and Pacific Oceans in connection with regional moisture variations to the Asian monsoon cycle.

The article reports on the study of the historical climate variations and climate change in the Brahmaputra basin such as Tibetan plateau (TP), Himalayan belt and the floodplains (FP). The study analyses the historical trends in temperature and precipitation of the TP, FP, and Himalayan belt through a global 100 year monthly high resolution dataset. It shows that precipitation in the basin is determined by the strength by the monsoons. It expresses that El Niño Southern Oscillation teleconnection does not have an important role in the changes in monsoon precipitation. The study also demonstrates the relationship among air temperature, FP, TP, and the strength of the monsoon.

The article offers information on the climactic teleconnections of summer monsoon streamflow to the Three Gorges Dam (TGD) at the Yangtze River Basin in China. From the period of 1882 to 2003, the summer monsoon inflow was analyzed at Yichang hydrological station (YHS). Statistical analysis was utilized to create a probative model for summer streamflow, followed by linear correlation maps using three-month ahead climate fields to determine the regions that exhibit climactic influences with streamflow at Yichang. The analysis shows regions in the eastern India and western Pacific oceans influences the YHS streamflow. It is inferred that an accurate climactic prediction can provide guidance for water management in the Yangtze River Basin.

The article presents a study on El Niño Southern Oscillation (ENSO) and the onset date of South China Sea summer monsoon (SCSSM). It mentions that the monsoon onset date (MOD) is determined by the change in direction of the zonal winds in the South China Sea from going towards the east to west in two consecutive pentads. It discusses that the ENSO is affected by the ocean heat content (OHC). The study found that the monsoon starts late in a period of warm ENSO. It also mentions that winds in the east of the Philippines affect the onset of the MOD. The study also relates the effects of cold subsurface water in the western North Pacific with SCSSM.