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Increasing variability of precipitation induced by climate change raises uncertainties for ecosystem services and agricultural production in the Poyang Lake Basin (PLB), China. Reanalysis precipitation datasets (RPDs) are attractive alternatives for monitoring the hydro‐climate cycles. However, their applicability in China has mainly been evaluated at the national scale, while less attention has been paid to the PLB or southeastern China. Here, we apply various metrics to evaluate the magnitude and spatial similarity of annual, monthly, different intensities and the spatial structure of precipitation from four reanalysis—the fifth global atmospheric analysis dataset of the European Center for Medium‐Range Weather Forecasts (ECMWF) (ERA5), Interim ECMWF Reanalysis (ERA‐Interim), Japanese 55‐year Reanalysis project (JRA55) and Modern‐Era Retrospective analysis for Research and Applications, Version 2 (MERRA‐2), against the rain‐gauges over the PLB during 1980–2018. The results showed that the detection capacity of ERA5 and MERRA2 shifted around 2002, whereas that of ERA‐Interim and JRA55 did not substantially change. Before 2002, ERA‐Interim had the lowest biases for the magnitude of annual, monthly and different intensities of precipitation (except for heavy rain), while ERA5 and MERRA2 had strengths in capturing spatial correlation. Notably, ERA5 and MERRA2 had region‐wide wet and dry biases, respectively, before 2002, which can be attributed mainly to the estimation of flood season precipitation (from April to June) and heavy rain. In contrast, the fractional contribution of light–moderate rain was underestimated and overestimated by ERA5 and MERRA2, respectively. However, after 2002, because of the improved reproducibility of flood season precipitation and heavy rain magnitude, the systematic biases of ERA5 and MERRA2 significantly decreased, especially for ERA5, which outperformed other RPDs on all aspects of precipitation. The conclusions of this paper suggest that the variation of applicability over time should be seriously tested before the utilization of RPDs in hydro‐climate analyses. [ABSTRACT FROM AUTHOR]

In this paper, we evaluate a 48‐member multiphysics ensemble using the Weather Research and Forecasting (WRF) model for the JJA extreme precipitation and temperature in 2003 over the CORDEX‐EA‐II domain. The simulated precipitation and temperature are reasonable in the subregions controlled by a large‐scale circulation, yet the biases for both precipitation and temperature are evident over the subregions where the effects of mesoscale processes are important. The performance of various combinations of WRF physical schemes for simulating the JJA precipitation is dependent on the region. Meanwhile, the cumulus and microphysical schemes have substantial influences on the simulation of precipitation, and the land surface models and cumulus schemes play crucial roles in the surface temperature. Our analysis shows that the combination of Noah for the land surface process, Lin for the microphysics, G3D for the cumulus parameterization, and CAM for the radiation scheme can provide the most reliable reproduction of both precipitation and temperature extremes over China. Ensemble analysis shows that the simulated climate extremes are usually accompanied by a large ensemble spread, implying sensitivities to the model physical processes in some subregions. The simulated wind fields at low‐to‐middle atmospheric levels display responses to the options of the land surface models and cumulus schemes. The essential impact of the land–atmospheric interaction on simulating the extremes can be largely attributed to the active convective processes. WRF has difficulties in reproducing the observed temporal evolution of the rainfall process, which consists of continuous large rainfall episodes in the observation data set during the simulation period. [ABSTRACT FROM AUTHOR]

In June after the onset of the East Asian summer monsoon season, rainfall on the south side of Hainan Island (HNI) of China exhibits a trimodal pattern with an unusual peak near noon. A typical case of 20 June 2017 is chosen to analyze the mechanisms through a convection‐permitting simulation together with rainfall observations. Clockwise rotation in low‐level winds is found at and off the coast of south HNI, leading to maximum onshore southwesterly winds in the late morning that is closely linked to the diurnal variation of rainfall. The offshore diurnal variations of low‐level winds are tracked upstream and attributed to boundary layer inertial oscillations over the inland plain of Indochina Peninsula. In addition, a short wide gap comprised mostly of hills lower than 700 m is located across the higher Annamite Range along the east coast of the Peninsula, right upstream of HNI. Nocturnal boundary layer low‐level jet (LLJ) forming over the plain passes through the gap with significant acceleration due to gap channeling and downslope flow effects, reaching peak intensity off the Peninsula coast at around 09 local standard time (LST). The enhanced LLJ propagates downstream towards HNI and impinges on the mountains at around 12 LST when rainfall reaches peak there. As the inertial‐oscillation‐indued perturbation winds approaching the Island weaken and eventually reverse direction, lifting weakens and low‐level stability increases as descending motion develops offshore. Rainfall on the southern Island therefore dissipates in late afternoon. Plain Language Summary: In June after the onset of East Asian summer monsoon, rainfall on southern Hainan Island (HNI) of China has an unusual peak near noon. A representative case is numerically simulated at 2 km horizontal grid spacing and analyzed. It is found that the diurnal variation of rainfall is closely linked to diurnal variation of low‐level onshore winds which reach peak intensity around noon, and the source of such variations can be tracked upstream to the inland plain of Indochina Peninsula (ICP). Over the plain, afternoon boundary layer mixing causes low‐level wind speed minimum while boundary layer low‐level jet reaches peak speed in early morning due to inertial oscillation after the boundary layer flow becomes freed of the surface friction when mixing is shut off. The peak perturbation wind is advected toward HNI, and reaches the Island around noon. The lifting by mountains on southern HNI of the intensified low‐level winds causes peak rainfall there around noon. In the afternoon, the perturbation winds weaken and eventually reverse direction, causing dissipation of rainfall. In addition, the low‐level flow is accelerated when it passes through a gap in the coastal Annamite Range of ICP, amplifying the effect of inertial oscillations. Key Points: Diurnal clockwise rotation in the low‐level winds is found to be linked to an around‐noon rainfall peak on southern Hainan Island (HNI) in JuneDownwind advection of the upstream boundary layer inertial oscillations is responsible for the around‐noon rainfall peak over HNIA gap across Annamite Range of Indochina Peninsula amplifies and transports boundary layer inertial oscillation signals downstream [ABSTRACT FROM AUTHOR]

Summary: Heavy rainfall events are expected to increase in frequency and severity in the future. However, their effects on natural ecosystems are largely unknown, in particular with different seasonal timing of the events and recurrence over multiple years.We conducted a 4 yr manipulative experiment to explore grassland response to heavy rainfall imposed in either the middle of, or late in, the growing season in Inner Mongolia, China. We measured hierarchical responses at individual, community and ecosystem levels.Surprisingly, above‐ground biomass remained stable in the face of heavy rainfall, regardless of seasonal timing, whereas heavy rainfall late in the growing season had consistent negative impacts on below‐ground and total biomass. However, such negative biomass effects were not significant for heavy rainfall in the middle of the growing season. By contrast, heavy rainfall in the middle of the growing season had greater positive effects on ecosystem CO2 exchanges, mainly reflected in the latter 2 yr of the 4 yr experiment. This two‐stage response of CO2 fluxes was regulated by increased community‐level leaf area and leaf‐level photosynthesis and interannual variability of natural precipitation.Overall, our study demonstrates that ecosystem impacts of heavy rainfall events crucially depend on the seasonal timing and multiannual recurrence. Plant physiological and morphological adjustment appeared to improve the capacity of the ecosystem to respond positively to heavy rainfall. [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]

Soil moisture is a consideration for soil conservation, agricultural production and climate modelling. This article presents a simple method for estimating soil moisture storage under water stress and storage depletion conditions. The method is driven by the common agro-hydrologic variables of precipitation (PPT), irrigation (IRR) and evapotranspiration (ET). The proposed method is successfully tested for the 152 000 km2 floodplain region of Hai River Basin using 48 consecutive months (2003-2006) of data. Soil moisture data from global land data assimilation system/Noah land surface model are validated with ground-truth data from 102 soil moisture monitoring sites. The validated soil moisture is used in combination with in situ groundwater data to quantify total water storage change (TWSC) in the region. The estimated storage change is in turn compared with gravity recovery and climate experiment-derived TWSC for the study area. The soil moisture and TWSC terms show favourable agreements, with discrepancies of <10% on the average. While there is no consistent seasonal trend in soil moisture, TWSC shows a strong seasonality. It is low in spring and high in summer. This trend corresponds with the IRR-PPT season in the study area. Change in groundwater and total water storage indicates storage depletion in the basin. Storage depletion in the region is driven mainly by groundwater IRR and ET loss. Despite the low PPT and high ET, there is narrowing seasonal trend in soil moisture. This is achieved at the expense of groundwater storage. IRR pumping has induced extensive groundwater depletion in the basin. It is therefore vital to develop cultivation strategies that aim at limiting IRR pumping and ET loss. Water management practices that not only reduce waste but also ensure high productivity and ecological sustainability could also mitigate storage depletion in the region. These measures could reduce further not only the seasonal trend in soil moisture but also that in groundwater storage. [ABSTRACT FROM AUTHOR]

The article presents a study which examines various processes which affect the dryness and wetness of the Tibetan plateau's boreal summer variability. The ERA-40 reanalysis was used to observe the precipitation on the plateau and analyze how surface temperature and atmospheric circulation influenced drought and wetness experienced in the Tibetan plateau. The study indicates that upstream and downstream Tibetan plateau conditions manifest importance for developing south-eastern Asian rainfall.

The plausible long-term trend of precipitation in China and its association with El Niño-southem oscillation (ENSO) are investigated by using non-parametric techniques. It is concluded that a greater number of decreasing trends, are observed than are expected to occur by chance. Geographically, the decreasing trend was concentrated in most parts of China, including the Songliao River, Hai River, Huai River, Yellow River, Zhujiang River, and southern part of the Yangtze River basins, whereas an increasing trend appeared primarily in the western and middle parts of China, mainly including the Inland River basin, and the northern part of the Yangtze River basins. Monthly mean precipitation for the summer and early autumn months generally decreased, with the greatest decrease occurring in August. The precipitation in spring from January to April and later autumn, including September and October, tended to increase, The teleconnection between precipitation and ENSO has been investigated by using the non-parametric Kendall's r. The correlation coefficients between the southern oscillation index (SOI) and precipitation show the areas with positive or negative associations. Approximately 20% of the stations exhibit statistically significant correlations between SOI and precipitation, of which 70% show a negative correlation, with most of them appearing in southeast China and several appearing in northwest and northeast China. Similar regional patterns are also observed when the precipitation records are further subdivided into El Niño, La Niña, and neutral periods. Statistical tests for the three kinds of time series were carried out using the non-parametric Wilcoxon rank-sum test and it is noted that the stations with significant differences in precipitation averages are mainly marked in the Yellow River basin and south China. The frequencies of below- and above-average precipitation that occurred during the El Niño, La Niña, and neutral periods are estimated as well. The result shows that greater precipitation may be associated with El Niño episodes in south China, but drought may easily occur during El Niño episodes in the Yellow River basin. [ABSTRACT FROM AUTHOR]