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All provinces of China respond to the central government, predict future carbon dioxide emissions, and formulate action plans detailing how the province intends to fulfill its target of carbon emission peaking before 2030. Based on the bottom‐up energy consumption prediction and top‐down goal verification, this paper constructs a set of regional carbon dioxide emission prediction methods. Compared to the traditional bottom‐up prediction method, this method could simplify the parameters while improving the prediction accuracy. This model is used to predict and analyze the process of carbon dioxide emission peaking in Zhejiang. The results show that the mean absolute percentage error of the retrospective prediction value is only 1.56%. Zhejiang will reach carbon dioxide emission peaking around 2029–2030, and the peak value will be 569.7 million tons. Different factors have different effects on the process of carbon dioxide emission peaking. There is a strong correlation between the peak time of carbon dioxide emission and the production time of major energy‐consuming projects in Zhejiang. Meanwhile, if the 16 nuclear reactors are not put into operation, Zhejiang will not be able to achieve the goal of carbon dioxide emission peaking. Besides, the basic data used in this model is mainly from the local statistical departments of the region. Thus, it can be applied to other provinces and regions conveniently. [ABSTRACT FROM AUTHOR]

A model‐circulation increment‐based dynamic statistical technique (MIDST) is proposed in this paper to improve the prediction of summer rainfall over southern China (SC) where quite low prediction skills have been found in the Beijing Climate Center Climate System Model version 1.1 with a moderate resolution (BCC_CSM1.1m). The results show that BCC_CSM1.1m can hardly represent the variability of the summer rainfall anomaly and its year‐to‐year increment over SC, and the skillful predictions are mostly confined over the middle reaches of the Yangtze River. Using the dynamic model output and statistical method, the MIDST is established to capture the coupled modes between the year‐to‐year increments of the summer rainfall anomaly and the associated simultaneous three‐dimensional coupled air‐sea circulation predictors. The cross‐validation indicates that the prediction skills of the MIDST are evidently improved for both the summer rainfall increment prediction and summer rainfall anomaly prediction compared with the direct BCC_CSM1.1m prediction. The skillful prediction can persist for long forecast leads over most regions except southwestern China. As the major predictability source of seasonal prediction, the intense response to changes in the circulation related to the El Niño‐Southern Oscillation (ENSO) is well captured, and thus, the performance improvement of the MIDST is primarily due to its more realistic representation of the incremental circulation related to the ENSO. [ABSTRACT FROM AUTHOR]

A significant wind shear event occurred in the early morning of 27 December 2009 at the Hong Kong International Airport (HKIA), leading to the diversion of three aircraft to the airport of Shenzhen (about 39 km to the north-northwest of HKIA). This paper documents the meteorological observations and predictions for the event. The significant wind shear arose from disruption of the prevailing easterly to southeasterly flow by the complex terrain to the south of the airport. It was well captured by the Doppler Light Detection and Ranging (LIDAR) systems at HKIA and, as such, the aircraft were given sufficient warning about the occurrence of significant wind shear. The headwind changes along the glide paths as measured by the LIDAR were consistent with the aircraft measurements. The observations of the remote-sensing instruments during the event, including the LIDAR, are described in the paper. Moreover, this paper discusses the possibility of including wind shear forecast information for flight planning purpose for this particular case. The forecast wind field near HKIA based on a high-resolution numerical weather prediction (NWP) model is described. For the present wind shear event, it appears that the occurrence of terrain-disrupted airflow near HKIA may be forecast about 6 h ahead. The timing of significant wind shear is, however, not reproduced well in the NWP forecast. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Atmospheric visibility profoundly impacts daily life, and accurate prediction is crucial, particularly in conditions of low visibility characterized by high aerosol loading and humidity. This study employed the WRF‐Chem model to simulate a severe wintertime haze pollution episode that transpired from January 17 to 19, 2010, in Central‐East China (112–122° E, 34–42° N). The results reveal that excluding aerosol–meteorology interactions led to underestimated PM2.5 concentrations and relative humidity in comparison with ground‐based measurement data, accompanied by a significant overestimation of visibility. Aerosols can engage with meteorological elements, particularly humidity, resulting in positive feedback. Upon considering these feedback interactions, the simulation results showed an increase of 5.17% and 1.99% in PM2.5 concentration and relative humidity, respectively, compared with the original simulation. This adjustment narrowed the bias between simulated and measured data. The overestimation of simulated visibility was reduced by 16% and 25% for the entire study period and the severe haze pollution period, respectively. These findings underscore the vital role of incorporating aerosol–meteorology interactions in visibility simulations using the WRF‐Chem model. Notably, the inclusion of aerosol–meteorological feedback significantly enhances the accuracy of visibility predictions, particularly during heavily polluted periods. [ABSTRACT FROM AUTHOR]

China's severe particle pollution could affect the regional climate and weather conditions that consequently threaten local to global food security. Yet, the underlying mechanisms and quantitative assessment of aerosols on crop yields remain unknown. Here, by integrating a meteorology–chemistry model and a crop model, we show the impacts of atmospheric aerosols on China's meteorology and soybean yields. We find that the potential yields of soybean would decrease in most parts of China due to direct aerosol radiation effects, while showing diverse responses in parts of the Northeast and North China Plain. Moreover, because of the high sensitivity of soybean growth to water, potential yield fluctuations are closely related to aerosol‐induced precipitation changes in most soybean‐growing regions of China. In particular, aerosols play the most important role during soybean's pod‐filling stage, in which the influence of both precipitation perturbations and negative solar radiative forcing is about 5–10 times that of air temperature on crop yield. Our study thereby identifies aerosol mitigation can bring a notable increase in crop yields, highlighting the potential for important co‐benefits in food security across polluting developing countries. [ABSTRACT FROM AUTHOR]

Mesoscale convective systems (MCSs) are important air water sources to the Three‐river‐source (TRS) region known as the "Chinese water tower." Using hourly equivalent blackbody temperature (TBB) data from geostationary satellites of Chinese Fengyun‐2 series during the warm season (May–August) in 2005–2020 and an objective algorithm, MCSs in the TRS are divided into meso‐α (MαCS), meso‐β (MβCS), and meso‐γ (MγCS), and MαCS and MβCS are subdivided into larger meso‐α (LMαCS), smaller meso‐α (SMαCS), larger meso‐β (LMβCS), and smaller meso‐β (SMβCS). Results show that a high‐frequency zone of MCSs in the TRS distributes along the source of the rivers. Most MCSs, except LMαCS, develop and dissipate in situ. The interannual variation in MCS frequency exhibits a decreasing trend, especially after 2013, mainly due to the decrease in MCSs in the source region of the Yellow–Lancang River. The occurrence of MCSs peaks in August, but MCSs are most likely to produce precipitation in July and usually generate between 1600–2200 h LST (UTC + 8). The precipitation caused by MCSs to the total precipitation (precipitation ratio, PR) accounts for about 40%; MCS PR is closely related to, and increases with, the horizontal scale of the MCS, with MαCS PR being the highest, exceeding 67%. The contribution of MCSs to precipitation is mainly reflected in weak precipitation, smaller than 10.0 mm/h. Most of the maximum precipitation of MCSs appears after MCSs reach their prime, with the maximum lag by MαCS up to 2 h. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, an objective identification technique for regional extreme events (OITREE) is used to identify regional drought events (RDEs) in southern China based on the daily precipitation dataset of 342 stations from 1961 to 2012. Generally RDEs in southern China occur over an entire year, with high frequencies from January to April and peak frequencies in February and March. The spatial distributions of frequency and intensity of RDEs are consistent, with high frequencies of more than 60 and the annual average number of drought days being more than 30 in most regions of southern China east of 105 ° E. The trend distributions of the frequency and intensity of RDEs in southern China are similar, with increasing trends in most western regions and decreasing trends in most eastern regions. The decreasing trends of RDEs in most eastern regions were mainly affected by the weakening of East Asia summer moonsoon (EASM) from the 1960s to the 1990s, which resulted in the summer main rain belts in eastern China moving from North China to southern China and caused the precipitation increasing in eastern regions of southern China from the 1960s to the 1990s. While the increasing trends of RDEs in most western regions were not only affected by the EASM, but also associated with the weakening of the India-Burma Trough (IBT) that caused less wet air transport to Southwest China and the decrease of precipitation in western regions of southern China. [ABSTRACT FROM AUTHOR]

Recurving tropical cyclones (TCs) can sometimes produce tornado outbreaks, while some TCs with similar tracks and intensities may produce none of tornado, which makes it challenging to assess tornado risk within recurving TCs. This study investigates two recurving TCs, Typhoon Yagi (2018) and Typhoon In‐Fa (2021), that made landfall in eastern China. Despite the similar recurving tracks and intensities, Yagi produced 11 tornadoes while In‐Fa produced none. Results show that both TCs were characterized by similar large‐scale conditions that were dynamically favourable for tornadoes during the recurvature process. The non‐tornadic In‐Fa even featured a higher shear and helicity environment in its northeast sector than did the tornado‐productive Yagi. The greatest difference between Yagi and In‐Fa is the thermodynamic instability owing to the different lower–middle‐tropospheric lapse rates that are attributable to the differences in air trajectories at low levels. In‐Fa featured marginal instability due to the cooler air at low levels because almost all of the air parcels came from the Pacific Ocean while most air parcels for Yagi came from the warm land. The cooler low‐level air tends to create higher relative humidity in In‐Fa's interior and thus leads to widespread precipitation which in turn also contributes to the low‐level cooling. The different air trajectories are demonstrated related to the TC's translation speed, size and synoptic characteristics days before TC's landfall. Numerical simulations suggest that the upward motions within the widespread precipitation regions of In‐Fa are overall weaker than those of Yagi due to the limited instability in the former. These findings suggest that even though two TCs were characterized by similar tracks, intensities and large‐scale forcings, their different low‐level air pathways may have significant influence on priming the mesoscale environment for supercell or tornado formation. [ABSTRACT FROM AUTHOR]

ABSTRACT Heavy rain events or rainstorms of various scales often occur in Hong Kong from April to September. In extremes cases, they lead to serious landslides and flash floods resulting in loss of life, and damage to property and infrastructure. With climate change, extreme rain events are projected to be more frequent and more intense in this region. A system to gauge and label the severity of rainstorms would be useful for identifying and communicating extreme conditions in warning and disaster prevention operations. In parallel, a better understanding of the characteristics of rainstorms would also be important for impact assessments and engineering design purposes. This paper formulates a practical framework to index the magnitude and severity of rainstorms in Hong Kong. An index termed as the Severity Index combining the magnitude of different rainstorm attributes is devised for quantifying the overall severity of rainstorms. This index is flexible to allow tuning for specific applications. [ABSTRACT FROM AUTHOR]

Projecting precipitation changes is essential for researchers to understand climate change impacts on hydrological cycle. This study projected future precipitation over the Hanjiang River Basin (HRB) based on the multimodel ensemble (ME) of six global climate models from Phase 6 of the Coupled Model Intercomparison Project (CMIP6). An ME method using the fusion of four machine learning (ML) algorithms (random forest [RF], K‐nearest neighbors [KNN], extra tree [ET], and gradient boosting decision tree [GBDT]) was proposed in this study. The future precipitation changes were investigated during 2023–2042 (Near‐term), 2043–2062 (Mid‐term), and 2081–2100 (Long‐term) periods, with reference to the base period 1995–2014, under three integrated scenarios (SSP1‐2.6, SSP2‐4.5, and SSP5‐8.5) of the Shared Socioeconomic Pathways (SSPs) and the representative concentration pathways (RCPs). The results show that: (1) the proposed ME method performs better than the ME mean and individual ML algorithms, with a correlation coefficient value reaching 0.88 and Taylor skill score reaching 0.764. (2) The precipitation under SSP5‐8.5 has the largest upward trend with the annual precipitation variation range of −9.27% to 112.84% from 2023 to 2100, followed by SSP2‐4.5 with −30.48% to 44.67%, and the smallest under SSP1‐2.6 with −37.19% to 37.78%, which show a significant trend of humidification over the HRB in the future. (3) The precipitation changes over the HRB are projected to increase over time, with the largest in the Long‐term, followed by Mid‐term, and the smallest in the Near‐term. (4) The northeastern parts of the HRB are projected to experience a large precipitation in the future, and the southeastern parts are smaller. (5) Uncertainties in the projected precipitation over the HRB still exist, which can be reduced by ME. The findings obtained in this study have important implications for hydrological policymakers to make adaptive strategies to reduce the risks of climate change. [ABSTRACT FROM AUTHOR]

The Urumqi Institute of Desert Meteorology under the China Meteorological Administration (CMA) launched an observational experiment with a boundary layer wind-profiling radar in Urumqi City in February to March 2010. As described in this paper, wind profiles from the experiment were used to first compare with radiosonde data measured simultaneously to verify the confidence of wind-profiling radar data, which was used to analyse the wind field characteristics and other related issues in a snowstorm process that took place in Urumqi on 28 March 2010. Both wind direction and speed derived from wind-profiling radar data have good consistency with those from radiosonde data (wind velocity coefficient: 0.85; wind direction coefficient: 0.78). Before the snowstorm, a surface wind shear occurred. After outbreak of the event, the local weather was dominated by northwesterly and northerly winds at increasing velocities, while temperature was dropping and air pressure increased. Through in-depth analyses of the time-height profiles of the snowstorm process, it can be determined on a preliminary basis that the snowstorm was induced by a cold front system that entered the area around 2200-2300 LST on 27 March. A shear line that developed from a lower to a higher altitude represented both height and location of the frontal zone, and the cold front motion was broadly in a northeast-southwest direction. The wind direction in the process changed counterclockwise with height: this was mainly governed by cold advection, and baroclinic instability was established soon after the overpass of the cold front, eventually leading to the snowstorm. During the weather event, the equivalent reflectivity factor Ze was consistent with the onset and end of the snowstorm, the height at which rain (snow) particles were formed and snowfall intensity. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

In the evening of 11 April 2011, vortex/wave shedding from a mountain to the south of the Hong Kong International Airport (HKIA) appeared to occur following the establishment of fresh to strong easterly airflow in Hong Kong. This paper documents the observations by the various meteorological instruments of the event and discusses the possibility of forecasting the vortex/wave shedding using a high resolution numerical weather prediction (NWP) model. The vortex/wave shedding was well observed by the Light Detection and Ranging (LIDAR) system at HKIA. The vortex/wave appeared as an area of reversed flow against the background east to southeasterly airflow in the airport area. It was detached from the mountain and moved to the northwest with the background southeasterly flow, with a gradual decrease of the spatial extent in the area of reversed flow. The vortex/wave brought about significant wind shear to both arrival flight paths to the west of HKIA, as evidenced from the headwind profile data measured by the LIDARs and the aircraft data. It had rather large vertical extent, reaching the top of the boundary layer, but did not extend downward to the surface, as shown from the vertical scans of the LIDAR and the surface wind observations. The shedding event is successfully captured by high-resolution NWP model with a spatial resolution of 50 m. The model output has a lead time of 6-7 h ahead of the event, indicating the possible occurrence of terrain-induced wind shear in the form of vortex/wave shedding from a mountain. As a result, the numerical simulation could be useful in giving an early alert to the aviation weather forecaster about the significant wind shear event, which could be hazardous to the landing aircraft. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

In the morning of 5 March 2010, an aircraft experienced tail strike when it departed from the south runway of the Hong Kong International Airport to the west. This paper documents the meteorological conditions in the tail strike event, and discusses the alerting and the forecasting aspects of the event. Based on the analysis of the aircraft manufacturer, the tail strike is believed to arise from significant wind shear (headwind loss) experienced by the aircraft. By analysing the surface and the LIDAR observations, it appears that the significant wind shear is related to disruption of the background southwesterly flow by the complex terrain near the airport. From the surface observations, there is a microscale cyclone at the western part of the south runway. The radial velocity image of the LIDAR also depicts an area of reverse flow in that region against the background southerly flow. The alerting of the wind shear based on the two wind shear alerting algorithms developed by the Hong Kong Observatory is discussed, and it turns out that the anemometer-based wind shear algorithm could successfully capture this wind shear occurring close to the ground. On the other hand, due to geometrical constraint, the LIDAR does not pick up the headwind loss experienced by the aircraft. The forecasting of this wind shear event is considered by performing high resolution (down to a horizontal resolution of 50 m) using a mesoscale numerical weather prediction model. The simulated headwind profile at the event time is generally consistent with the aircraft data, though the headwind loss in the simulation is smaller than the reality. Together with the forecast wind gusts, it may be possible to alert the aviation weather forecaster at an earlier time about the occurrence of terrain-induced wind shear over the south runway in this particular event. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Spring gale is a dynamic power for DSs (DSs), which presents a close connection with the DSs of northern China. Both display declining trends during the past 68 years (1954–2021). In this study, the influencing factors of spring gales and DSs around northern China and possible adjustment functions of the East Atlantic (EA) teleconnection pattern have been investigated. It was found that the major systems controlling spring gales include the North Polar vortex (NPV), mid–high‐latitude blocking highs (BHs), air pressure status of the Tibetan Plateau (TP) over the Eurasian continent, India–Burma trough (IBT) and western Pacific subtropical high (WPSH). Under synthetic atmospheric circulation conditions of an enlarged NPV, lower air pressure over the TP, a strong IBT, and a southeastward‐retreated WPSH, spring gales increase, and the frequency of DS occurrence is increased, and vice versa. Additionally, spring gales are also negatively affected by BHs. The most important is the Baikal BH, which has influence not only in previous seasons but also in the contemporary spring. Furthermore, the NPV and IBT have close negative correlation with the EA pattern, whereas the TP and WPSH have positive correlation with the EA pattern both in previous seasons and in the contemporary spring. A high‐pitched EA pattern results in a strong western current north of Lake Baikal, which may prohibit the expansion of the NPV in the sector of northern China. A shrunk NPV means infrequent cold air attacks and decreased gales and DSs. [ABSTRACT FROM AUTHOR]

The microphysical processes of cloud and precipitation in the Tianshan Mountains still remain unclear due to the complex terrain and the lack of ground-based observational data. In this study, the characteristics of summer raindrop size distribution (RSD) in the western and central Tianshan Mountains of China were investigated in 2020 and 2021. According to the average raindrop spectra, the RSD characteristics exhibit significant differences that the concentration of medium and large particles is relatively higher at Zhaosu than that at Tianchi. Weak precipitation prevails in the Tianshan Mountains most of the time, yet moderate rainfall and heavy rainfall have a great impact on the accumulated rainfall amount. For each rainfall rate class, raindrops of diameter less than 0.75mm have a lower concentration and raindrops of diameter greater than 3 mm have a higher concentration at Zhaosu as compared to those at Tianchi. Compared with Tianchi, Zhaosu has a larger mass-weighted mean diameter (Dm) and a lower normalized intercept parameter (log10Nw). Compared with the classical convective spectrum, the RSDs at both Zhaosu and Tianchi are similar to the continental convective cluster. The relationships between the shape and slope (μ–Λ), and radar reflectivity and rainfall rate (Z– R) exhibit a significant difference in the western and central Tianshan Mountains of China. [ABSTRACT FROM AUTHOR]

The surface evapotranspiration (ET) process is the key link in the interaction between land and atmosphere. However, the influence of different environmental factors on ET over transitional climate zones and the physical pattern of the interaction between multiple factors remain unclear. Therefore, based on the continuous observation data during the vegetation growing season of a typical grassland in the Semi-Arid Climate and Environment Observation of Lanzhou University (SACOL) station from 2007 to 2012, the influence pattern of multiple environmental factors on ET over China's transitional climate zone was analysed. Each environmental factor exhibited significant seasonal and interannual variations. The mean value of ET was 1.67 mm day-1. Although the maximum values of sensible heat flux and vapour pressure deficit occurred in April and June, respectively, the maximum values of other environmental factors appeared from July to August. Net radiation, soil moisture, and normalized difference vegetation index (NDVI) were the main controlling factors of ET over the grassland, with correlation coefficients of 0.54, 0.52, and 0.46, respectively. The analysis of multiple environmental factors showed that when soil moisture, wind speed, net radiation, and NDVI reached 0.2 m³ m-3, 2 m s-1, 100 W m-2, and 0.2, respectively, ET varied in contrast with vapour pressure, vapour pressure deficit, and air temperature under the influences of weather processes, land–atmosphere coupling, and drought stress. These findings deepen our understanding of the role of ET in the land–atmosphere coupling process over the transitional climate zone in China. [ABSTRACT FROM AUTHOR]

A tornado/waterspout associated with a supercell thunderstorm was observed in the adjacent waters of southern China on the evening of 18 April 2019. The case was documented using surface weather observations and Doppler radar data. A weather station near the tornado/waterspout, recorded wind gusts corresponding to hurricane intensity for a few seconds, never observed before in the region. The Doppler velocity associated with the tornado/waterspout was analysed and the vertical profile of the velocity could be very useful for wind engineering applications in the region. Dual‐polarization observations also were analysed and exhibited some similar signatures documented in supercell tornadoes in other parts of the world. Predictability of the tornado/waterspout was studied using a numerical weather prediction model. It showed that the location and timing of the waterspout/tornado could be roughly reproduced, and the model might be used to give earlier alerting to the vessels operating in the south China coastal waters. [ABSTRACT FROM AUTHOR]

Multi‐source remote sensing precipitation products are being used more and more frequently for rainfall analysis and hydrological applications around the world. The aim of the present study was to assess the variances and uncertainty of long‐term precipitation and corresponding hydrological simulations from 1984 to 2016 using rain gauge measurements, two satellite rainfall products retrieved from the Climate Prediction Center (CPC) and the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks – Climate Data Record (PERSIANN‐CDR) respectively, along with rainfall reanalysis data from the ERA‐Interim over the lower Yangtze River basin, China. The results indicated overestimation from ERA‐Interim and PERSIANN‐CDR on seasonal rainfall. CPC rainfall estimation had marginal bias with rain gauge measurements among all the remote sensing rainfall products on a daily scale, while the ERA‐Interim tended to overestimate when the rainfall rate was less than 50 mm. On a monthly scale, CPC rainfall estimations were very close to the rain gauge measurements, with a correlation coefficient of 0.96, whilst the ERA‐Interim rainfall products showed significant overestimation in February, March and September. Nevertheless, all remote sensing rainfall products achieved good performance in June and July, showing promising potential to be an alternative to rainfall data for long‐term water resource analysis. Furthermore, ERA‐Interim rainfall products did not perform as well as the other rainfall sources in flow simulations, as evidenced by the large root‐mean‐square error and bias. CPC rainfall products outperformed all other rainfall sources in terms of the Nash–Sutcliffe coefficient at all temporal scales. In addition, the skill scores suggested that the performance of the streamflow simulation improved significantly on a monthly scale, with a higher Nash–Sutcliffe coefficient and smaller total streamflow errors. [ABSTRACT FROM AUTHOR]

The performance of the forecasts of the European Centre for Medium-Range Weather Forecasts' (ECMWF) Integrated Forecasting System (IFS) with a horizontal resolution of 0.125° is assessed through comparison with station raingauge data in the warm season (May-October) in the period 2017-2018 over southwestern China. The mean state of rainfall amount, frequency and intensity, as well as the diurnal cycle of precipitation, are involved in the evaluation. The IFS can capture well the spatial distributions of rainfall amount, frequency and intensity in the gauge data, but the rainfall frequency is generally larger and the intensity is weaker in the IFS. The rainfall events of the IFS usually start and peak much earlier, and the afternoon rainfall peaks are overestimated. The discrepancy between the gauge data and the IFS is larger over the western part of southwestern China. The results indicate that the IFS forecasts show considerable uncertainty when moving to the sub-daily scale, especially over areas with complex topography. When the IFS forecasts are applied operationally, the deviations (as revealed in this study) should be paid more attention. [ABSTRACT FROM AUTHOR]

Determining the response of abrupt temperature changes/warming hiatuses to changes in their influencing factors can provide a reference for investigating their mechanism. The present study, using the Mann-Kendall test, based on data (including average minimum temperature (Tmin), average temperature (Tave) and average maximum temperature (Tmax)) recorded at 357 meteorological stations in northern China and its surrounding regions as well as large-spatial- scale data (e.g. Atlantic multidecadal oscillation (AMO), global radiative forcing of CO2 (RFCO2) and radiative forcing of annual greenhouse gases (RFAGG)) for the period 1951-2016, the characteristics of abrupt temperature changes/warming hiatuses and their response to their influencing factors were qualitatively and quantitatively determined. The following results were obtained. Overall, from the late 1970s to the 1990s, as the RFAGG continuously increased, the Pacific decadal oscillation (PDO) remained in a positive phase, the AMO and total solar radiation (SR) continuously increased, the multivariate El Niño southern oscillation (ENSO) index (MEI) changed abruptly, the wind speed (WS), atmospheric pressure (AP) and relative humidity (RH) in each zone continuously decreased/increased, their trends changing subsequently, and abrupt changes in the three temperature metrics (i.e. the Tmin, Tave and Tmax) occurred in each zone during the period 1977-2004. Similarly, in the 1990s, particularly after 1998, as the increase in the AMO slowed, the PDO was in either a positive phase but exhibited a decreasing trend or a negative phase, the MEI and SR decreased, the WS, AP and RH decreased/ increased, with subsequent changes in trends, and warming hiatuses occurred. The sensitivities of the responses of the Tmin to changes in the three types of influencing factors were the highest, followed by those of the Tave and Tmax. The effects of various influencing factors on the three kinds of temperature change and warming hiatus have strong spatial and temporal differences. As a result, there was a strong spatial difference in the year of the abrupt temperature change and the warming hiatus. [ABSTRACT FROM AUTHOR]

The accurate assessment of marine wind characteristics is receiving increasing attention because of its practical importance in diverse areas. However, the reliable measurement of marine winds is often insufficient mainly because of the limitation of the instrumentation used. In the present study, four year lidar measurement data, recorded continuously from March 2012 to November 2015, are collected at an offshore platform near Lamma Island in Hong Kong, China, to obtain useful marine meteorological information, with a particular interest in the seasonal and diurnal variations of wind speed, wind shear co-efficient (WSC) and veering wind angle. It is shown that the wind speed and Weibull parameters generally exhibit evident monthly variation. The maximum monthly wind speed occurs in February, with values between 7.41 and 8.13 m·s-1 depending on the height, and the monthly minimum occurs in August, with values between 4.66 and 5.27 m·s-1. The Weibull scale parameter shows a similar monthly pattern with wind speed, while the Weibull shape parameter peaks in June. Furthermore, the diurnal pattern of both wind speed and Weibull parameters is closely tied to seasonality. The WSC covering the bottom and top layers of the wind turbine is likewise examined. Larger WSCs are obtained during hotter months, while smaller WSCs are associated with cooler months. The diurnal pattern of the WSC shows reasonable agreement among different seasons, although the magnitude is somewhat different. The veering angle generally increases with height. Its monthly pattern reveals a maximum in May, reaching up to 17.8° within the height of concern. Pronounced monthly and diurnal patterns of veering angles are observed at higher altitudes. [ABSTRACT FROM AUTHOR]

Dual‐frequency radar (DFR) could improve the accuracy of estimating the microphysical properties of rain profiles. Unfortunately, factors that cause inaccuracies in retrieved rain profiles include uncertainties in raindrop size distribution (DSD) parameterizations, DFR retrieval methods and radar measurement errors. The primary objective of this study was to assess the uncertainties in retrieving rain profiles to offer insight into application considerations for ground‐based DFRs in China. The uncertainties caused by DSD models are assessed by comparing attenuation coefficients and rain rates from DFR algorithms with those directly derived from DSD spectra from disdrometers. Then, based on a DSD model, the impacts of retrieval methods, radar range resolution, measurement error and errors in temperature on DFR retrievals are explored by comparing the rain profiles obtained using DFR algorithms with those directly output from the Weather Research and Forecasting model. Overall, the impact of measurement error on the DFR retrievals is relatively significant for both the forward retrieval method and the iterative backward retrieval method and should be eliminated in practical applications. At an individual uncertainty level, the impact of DSD parameterizations on the retrievals from the dual‐frequency technique is less than ±10% bias when the shape factor μ of the gamma distribution ranges from 2 to 4. The retrieved rain profiles from the forward retrieval method are relatively sensitive to radar range resolution and the retrieval performance can be improved with increasing the range resolution, while the iterative backward retrieval method exhibits stable retrieval performance. The impact of temperature errors on the retrieved rain profiles is negligible. [ABSTRACT FROM AUTHOR]

The goal of this study was to improve the accuracy of model forecasting, such that forecasters could use model products to make more efficient daily weather predictions. Historical data of the 12 hr following a given time for various meteorological factors from the control forecasts of the European Centre for Medium‐Range Weather Forecasting (ECMWF) between 20 ° and 40 ° N latitude and 110 °–130 ° E longitude were used to verify the performance of the proposed method. Eight major meteorological factors were selected via correlation analysis between control forecast meteorological factors and real‐time rainfall. The samples were divided into four types using the K‐means clustered method. Each type was respectively modelled by long short‐term memory (LSTM) in order to correct rainfall forecasts for eastern China. The eight major meteorological factors were used as the model input, and the differences between real‐time rainfall data and model‐forecast rainfall were used as the model output. The corrected results revealed that the root mean square error decreased by 0.65, and the threat scores of light rainfall and rainstorms were improved. [ABSTRACT FROM AUTHOR]

Results from object‐based verification of rainfall forecasts for landfalling tropical cyclones (TCs) over China during the period 2012–2015 are presented. The sample consists of 25 landfall events and 133 operational numerical forecasts from the TC version of the Australian Community Climate and Earth System Simulator. Mean equitable threat scores, probabilities of detection and false alarm ratios for the 30 mm isohyet for the unadjusted forecasts at 0–6 hr (essentially the initialization) are (0.23, 0.55, 0.65), while the performance measures of 24 hr forecast accumulations are the best for the 0–24 hr forecast (0.37, 0.67, 0.40) and then worsen to (0.16, 0.38, 0.66) for the 48–72 hr forecast. Forecast ability also decreases with the increase in rainfall amount. The contiguous rain area (CRA) verification method is used to diagnose the source of systematic errors from the displacement, rotation, volume and pattern of the forecasted rain fields. Results show that the errors are mostly from rainfall patterns, followed by displacement errors, particularly for very heavy rain. After application of the displacement and rotation adjustments of the CRA method, averaged errors improve by about 15%. Results suggest that rainfall prediction will continue to improve with improved track prediction, but more work is needed on model initialization and the prediction of TC structure. The study has uncertainty related to the limited sample size, which could cause large variability, particularly for heavy rainfall at 6 and 72 hr. However, the results still represent a useful benchmark for future verification of landfalling TCs. [ABSTRACT FROM AUTHOR]

A high temporal–spatial resolution (1 hr/1 km) gridded temperature data set with a long time‐series (2006–2015) is established for Zhejiang province, China, which has a complex terrain, including plains, hills, basins, mountains, islands and oceans. A comprehensive analysis method is used to combine regional surface station data with reanalysis data from the European Centre for Medium‐Range Weather Forecasts (ECMWF) such that the observations at the stations are reproduced, and the reanalysis data provide the spatial structure for the interpolation. The elevation correction method and inverse distance‐weighted interpolation method are selected for comparison. The quality of the data set is evaluated and analysed by comparison with the cross‐validation results, third‐party data validation and other gridded data sets. The results show that the comprehensive analysis method provides the best outcome, followed by the inverse distance‐weighted method, and the reanalysis data elevation correction method has the worst result. The temperature error obtained from the gridding methods increases with altitude, decreases with increasing station density and varies with different synoptic conditions. The obtained data set can describe the temperature feature of peaks and valleys more precisely, which produces lower errors and higher spatial correlation co‐efficients compared with observation than the other gridded data sets. Therefore, the established data set can meet the needs of fine meteorological businesses and has potential applications in many fields. [ABSTRACT FROM AUTHOR]

Extremely inhomogeneous aircraft observations were obtained by the Hong Kong Observatory when Typhoon Nida (2016) approached South China. However, only part of Typhoon Nida was observed due to limitations of the flight range. To investigate an effective scheme for assimilating inhomogeneous aircraft observations, a multigrid 3D variation (m3DVAR) system, with the assistance of a bogus vortex, was employed. The arithmetic mean was used to reduce the representative error of the turbulence scale before assimilation. Track and intensity forecasts were improved by assimilating aircraft observations and bogus data. The assimilation of aircraft observations could play an important role in the improvement of intensity forecasts for Nida because adding bogus data is of help to propagate the sparse and inhomogeneous information in the m3DVAR system. The assimilation of pressure (horizontal wind) was also found mainly to contribute to the large magnitude (sophisticated distribution) of increments. Track and intensity forecasts of Typhon Nida (2016) are improved by assimilating aircraft observations and bogus data. The assimilation of aircraft observations could play an important role in the improvement of intensity forecasts for Nida because adding bogus data is of help to propagate the sparse and inhomogeneous information in the multigrid 3D variation system. [ABSTRACT FROM AUTHOR]

The rainfall distribution associated with landfalling tropical cyclones (TCs) along the South China coast are examined using radar data from Hong Kong Observatory (HKO). This preliminary study relates the landfall direction, and possible rotations/transitions of TC rainfall asymmetries before and after the landfall. Three types of landfalling TCs on the South China coast are categorized: from the east, normal to the coast and from the southwest. For those from the east, the rainfall maximum rotates anticyclonically from the southwest before later landfall to the northwest. TCs making landfall perpendicular to the coast have a rainfall maximum remaining in the southwest quadrant throughout the landfall process. For TCs making landfall from the southwest, the rainfall maximum rotates cyclonically from the southeast before later landfall to the northeast. The relative importance of the impact of land properties and vertical wind shear on these rainfall asymmetries is investigated by using a numerical model. Sensitivity tests show that the rotations/transitions of landfalling TC rainfall asymmetry appear to be insensitive to land properties (e.g. moisture availability, surface friction and topography), but result primarily from changes in the orientations of the vertical wind shear in the environment. However, the surface friction of the landmass appears to contribute to the enhancement of rainfall intensity. The rainfall distribution associated with landfalling tropical cyclones (TCs) along the South China coast are examined using radar data. Three types of landfalling TCs are categorized based on the landfall direction, and possible rotations/transitions of TC rainfall asymmetries before and after the landfall. The rotations/transitions of landfalling TC rainfall asymmetry appear to be insensitive to land properties (e.g. moisture availability, surface friction and topography), but result primarily from the orientations of the vertical wind shear in the environment. [ABSTRACT FROM AUTHOR]

ABSTRACT: Numerous drought indices based on single or multiple variables have been developed for the assessment of drought. This study aimed to detect the variability of droughts by applying four drought indices, the standardized precipitation index, the reconnaissance drought index, the standardized precipitation evaporative drought index and the effective drought index, at five meteorological stations in the Songhua River basin (SRB) in China during 1962–2013 and at two meteorological stations in the Indus River basin (IRB) during 1980–2013 using different timescales (3, 6, 9 and 12 months). Moreover, a Mann−Kendall trend test at the 5% significance level was used for the assessment of drought trends in the basins. The results indicated that the 12 month data series for the SRB and the 6 month data series for the IRB were appropriate for assessing dry conditions and for comparing the drought indices. Pearson's correlation analyses between the drought indices results and the meteorological variables revealed that the standardized precipitation index is a better drought index for the assessment of drought in the SRB (r = 0.99). The results also showed that the standardized precipitation evaporative drought index versus the reconnaissance drought index is better at identifying drought in the IRB with a Pearson's correlation value r of 0.98. Severe and extremely dry conditions prevailed between 1990 and 2001 in the SRB, and there were extreme drought conditions with an intensity of −2.00 in the IRB during 2001–2002. Overall, this study provides insights into choosing the appropriate time interval and drought index for a specific region to identify the severity of droughts. [ABSTRACT FROM AUTHOR]

ABSTRACT The present study aims to understand the public opinion on the Chinese Public Weather Service and evaluate its benefits. Statistics based on a nationwide survey conducted in China in 2006 show that the receipt and perception of weather information vary across different ages and groups. People obtain weather information from various sources (television ranks first); younger generations favour new media. There is a high demand for information services related to severe weather and short-range weather, which have the largest impact on daily lives and professional needs. The respondents' satisfaction with the current weather service and forecast accuracy are very high, although the accuracy of weather forecasts requires improvements. The benefits of the Chinese Public Weather Service and cost-benefit ratios are evaluated via direct, indirect and reverse willingness-to-pay evaluation models. For the entire country, the benefit of the Chinese Public Weather Service is estimated to be at least 46.482 billion Chinese Yuan ( CNY), which accounted for 0.22% of the Chinese gross domestic product ( GDP) in 2006; the national cost-benefit ratio is 1:26. The regional cost-benefit ratios of the Chinese Public Weather Service exhibit a wide range from 1:2 to 1:81 over different provincial-level regions. The cost-benefit ratios are much higher in economically developed areas (Central and East China) than in economically underdeveloped areas (Northwest China). The social development level, especially certain aspects of primary industry and transportation, is closely related to the cost-benefit ratio of the Chinese Public Weather Service. These findings can assist the China Meteorological Administration and its supervised meteorological bureaus in providing a weather service that meets the public needs effectively. [ABSTRACT FROM AUTHOR]

The Changwu tableland is located in the semi-humid to semi-arid transition area of the Loess Plateau, China. In the present study, the daily potential evapotranspiration (ET0) of the Changwu tableland was calculated using the FAO Penman-Monteith (FPM) equation for the years 1957-2012, and the temporal variation and frequency distribution characteristics were analysed. The results indicate that the annual average ET0 of the Changwu tableland was 949.3 mm, varying from 789.2 to 1093.3 mm; a slight downward trend with a rate of -0.48mm year-1 was found. An abrupt increase occurred in 1994. The ET0 values that correspond to frequencies of 5, 10, 25, 50, 75, 90 and 95% were 1076.8, 1047.6, 999.7, 947.8, 897.3, 853.0 and 827.0 mm, respectively. The recurrence intervals of maximum and minimum ET0 were both more than 50 years. The contributions of Tmax, Tmin, vapour pressure, wind speed and sunshine hours to changes in ET0 were 0.74, 0.07, -0.51, -0.57 and -0.23, respectively. The change in ET0 and the meteorological factors in the Changwu tableland are worthy of attention; measures to reduce the negative impacts of climate change are necessary. [ABSTRACT FROM AUTHOR]

The impact of urbanization for a summertime rainstorm process in the Yangtze River Delta was investigated based on two 96 member ensembles using the Weather Research and Forecasting (WRF) model. Results show that the increase of precipitation mainly occurs downwind of the city belt in this region. The increase and decrease of precipitation forms two zigzag belts in the precipitation area. The t-test illustrates that the discrepancies of near-surface environment around the city belt, the precipitation downwind of the city belt as well as the atmospheric variables in the lower troposphere over the rain belt, caused by urbanization, is significant in such a short-term rainstorm process. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

ABSTRACT Between January and May 2011, southern China suffered perhaps the most severe drought since 1954. This investigation was carried out based on OLR ( Outgoing Long-wave Radiation) data derived from NOAA/ AVHRR satellite observations, precipitation records at 753 meteorological stations in China and NCEP reanalysis data during 1990 and 2011. This was done by first calculating the January to May climate averages of all required atmospheric parameters during 1990 and 2011, and then calculating the January to May 2011 anomalies (the difference between the parameter value in January to May 2011 and its climate average), with the goal to understand the dynamic and thermal mechanisms behind the 2011 5 month drought. Results show that during the drought: (1) the large-scale circulations were abnormal with a strengthened Mongolian High, a weakened subtropical high and abnormal northerly winds prevailing over southern China and the South China Sea; (2) the air was drier due to the anomalous deep dry-cold air column at middle and lower levels over southern China (linked to the northerly wind from the Mongolian anticyclone and the northwesterly wind from the Yellow Sea cyclone); (3) the abnormal air temperature structure, i.e. warm at higher levels (due to the abnormal South Asian High) and cold at middle and lower levels (due to the anomalous deep dry-cold air column over southern China), and (4) a formation of an abnormal mesoscale circulation structure, with the cyclonic convergence at the mid-level low (due to the Yellow Sea cyclone), the anticyclonic divergence at the low-level small high (due to the Mongolian anticyclone) and the resulting abnormal vertical downward movement over southern China. All these factors contributed significantly to the January to May 2011 drought over southern China. [ABSTRACT FROM AUTHOR]

From 1961 to 2008, the overall frequency of dust storms in northern China has shown an unquestionable reduction. However, the Hunshdak Sandy Lands of northern China display an increasing frequency in dust storm activities, especially during the period 2001 to 2008. In an attempt to explore the cause of this increase, a comprehensive investigation was conducted by examining the climate variables, the average normalized difference vegetation index (NDVI) and the local inhabitant migrations. The climate variables include local precipitation, temperature, aridity, evaporation, relative humidity, soil moisture and wind speed. Moreover, by analyzing the 2001-2008 average anomaly charts (relative to the 30 year climatology of 1971-2000) of the upper air and surface conditions, an advantageous atmospheric circulation background for drought development over the Hunshdak was confirmed. Meanwhile, a multivariable step-regression model was employed to distinguish the significant variables of the climate elements mentioned before. The model output suggests that aridity is the leading factor impacting the Hunshdak dust storm frequency. During 2001 to 2008, the lack of local precipitation, higher temperature and strong evaporation deteriorated the local surface condition to below that before 2000, which is verified by the reduction of vegetation cover (NDVI), soil moisture and relative humidity. Furthermore, compared to the 30 year climatology of the wind speed observed during dust storm occurrence time, the mean velocity of 2001-2008 was reduced by 3.0 m s−1, indicating that even with relatively weaker winds, dust storms still occurred primarily due to the degeneration of surface conditions around the Hunshdak. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Climate change in the Pearl River Delta (PRD) has attracted growing attention along with rapid urbanization in Southern China. Annual mean temperatures in this area have increased more rapidly than the average level, which can be attributed to population expansion and land use changes in this region. In this study, temperature records from 31 weather stations in the PRD in Guangdong, China and the global dataset from the National Centres for Environmental Prediction (NCEP) Reanalysis (R-2) are analysed. Data from NCEP R-2 and temperature soundings taken at 850 hPa are used to define the background temperature. Anthropogenic temperature is then calculated according to the observed temperature and background temperature. The relationships of anthropogenic temperature to population density and area ratio of land-use types are analysed by univariate and multiple regression analysis techniques. Spatial distribution of anthropogenic temperature in the daytime is different from that at night. Model results indicate that relationships between population and anthropogenic temperature in the daytime are logarithmic or inverse but tend to be linearly related at night. Multiple regression analysis conducted on the area ratios of land-use types and anthropogenic temperature shows that a strong relationship exists between the two in spring and autumn. Positive correlations with anthropogenic temperature from arid land, water bodies and urban land, as well as a negative correlation from woodland, are detected regardless of time of day. Contrary to the paddy field, grassland and sea show a negative correlation with anthropogenic temperature in the daytime and a positive correlation at night. Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Aedes albopictus, which can transmit Dengue fever, is one of the common mosquitoes in Hong Kong. To study the effect of weather on the abundance of Aedes mosquitoes in Hong Kong, ovitraps were set up at an unperturbed experimental site for a period of 7 days every month to record the Ovitrap Index, an often-adopted parameter to indicate the abundance of mosquitoes at a site, from July 2007 to June 2009. Analysis of the Ovitrap Indices at the experimental site and the weather elements collected from a nearby automatic weather station in the same period showed that the Ovitrap Indices were highly correlated with the mean air temperature over a 22 day period comprising the preceding 15 days and the 7 days when the ovitraps were in place, as well as the total rainfall over the 15 day period prior to the setting up of the ovitraps. A Climate Aedes Mosquitoes Abundance Model was developed based on the observations to predict the abundance of Aedes mosquitoes in Hong Kong. The model can provide a useful tool for planning of preventive and control measures against Aedes mosquitoes in Hong Kong. Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The article discusses the features of atmospheric circulations for dust storm springs in northern China and the exposure of probable seasonal forecast signals. It states that northern China is one of two regions in China mostly frequented by major dust storms. It states the evolutionary characteristics of the atmospheric circulations which include the previous summer, the previous winter and springtime. The article also includes detection of seasonal forecast signals.