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The winter extreme precipitation over South China (SC) experiences a large year‐to‐year variability, causing uncertainty in its prediction. Here, we find that the boreal winter sea ice concentration (SIC) in the Okhotsk Sea can serve as a precursor to the following winter's extreme precipitation frequency (EPF) over SC, which has important implications for its prediction. Further analysis reveals that the Okhotsk Sea SIC anomalies help to reinforce North Pacific Oscillation‐like atmospheric variability over the North Pacific, which induces the development of El Niño‐Southern Oscillation (ENSO)‐like SST anomalies in the equatorial eastern Pacific. The ENSO may act as a "power amplifier" to boost the impact of the Okhotsk Sea winter SIC anomalies on the following winter EPF over SC via a positive atmosphere–ocean feedback process. Our findings suggest that the Okhotsk Sea SIC may act as a potential precursor for the winter EPF over SC leading by about 1 year, and further improve our understanding of extratropical‐tropical interactions and aid predictability of winter extreme precipitation over SC. [ABSTRACT FROM AUTHOR]

Northeast China (NEC) is an important crop production base in East Asia. The monthly evolution of precipitation during spring sowing from April to May is of significance for agricultural activity and production over NEC. This study first investigates the predominant modes of April-to-May precipitation evolution over NEC and then explores their connections with North Atlantic sea surface temperature (SST) anomalies during 1979–2016. The first mode obtained using a multivariate empirical orthogonal function (MV-EOF1) shows an out-of-phase change in NEC precipitation anomalies from April to May, but the second mode (MV-EOF2) shows an in-phase change. Further analysis indicates that SST variability over mid-latitude North Atlantic (MNA) is related to MV-EOF1 by exciting a wave train from MNA to Eurasia. The wave train position is located more westward in May relative to April, leading to reverse atmospheric circulation and precipitation anomalies over NEC between April and May. The changes in position of circulations may be related to the westward shift of the North Atlantic storm track from April to May. MV-EOF2 is related to SST variability over northern tropical Atlantic (NTA). In April, NTA SST anomalies impact NEC precipitation through mid-latitude Eurasian wave train and Walker-like circulation anomalies between the Atlantic and Pacific Oceans. In May, the mid-latitude pathway is effective; however, the tropical pathway is significantly weakened, which may be related to the weakened intensity of NTA SST-induced tropical diabatic heating. Numerical simulations can reproduce the linkage between the North Atlantic SSTs and the pronounced atmospheric circulation anomalies in the observation, further confirming the impacts of North Atlantic SSTs on NEC April-to-May precipitation evolution. [ABSTRACT FROM AUTHOR]

Based on the long-term reanalysis datasets and the multivariate copula method, this study reveals that the frequency of summer hot drought events (SHDEs) over northeastern China (NEC) shows interdecadal variations during 1925–2010. It is revealed that the summer sea surface temperature (SST) over the North Atlantic has a significant positive correlation with the frequency of SHDEs over NEC on the decadal time scale, indicating a potential influence of the Atlantic multidecadal oscillation (AMO). Further analyses indicate that during the positive phases of the AMO, the warming SST over the North Atlantic can trigger a stationary Rossby wave originating from the North Atlantic, which splits into two wave trains propagating along two different routes. One is a zonally orientated wave train that resembles the Silk Road pattern, whereas the other is an arching wave train that resembles the polar–Eurasian pattern. A negative (positive) phase of the Silk Road pattern (polar–Eurasian pattern) may result in the weakened westerly wind along the jet stream, the downward vertical motion, and the anomalous positive geopotential center over NEC, providing favorable conditions for precipitation deficiency and high temperature and resulting in increased SHDEs. Thus, the Silk Road pattern and the polar–Eurasian pattern serve as linkages between the AMO and SHDEs over northeastern China in summer on the interdecadal time scale. Model simulations from CAM4 perturbed with warmer SST in the North Atlantic show precipitation deficiency and high temperature conditions over northeastern China in summer, supporting the potential impacts of the North Atlantic SST on SHDEs over northeastern China. The results suggest that the phase of the AMO should be taken into account in the decadal prediction of SHDEs over northeastern China in summer. [ABSTRACT FROM AUTHOR]

A 600-year integration performed with the Bergen Climate Model and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data were used to investigate the impact of strong tropical volcanic eruptions on the East Asian summer monsoon (EASM) and EASM rainfall. Both the simulation and NCEP/NCAR reanalysis data show a weakening of the EASM in strong eruption years. The model simulation suggests that North and South China experience droughts and the Yangtze-Huaihe River Valley experiences floods during eruption years. In response to strong tropical volcanic eruptions, the meridional air temperature gradient in the upper troposphere is enhanced, which leads to a southward shift and an increase of the East Asian subtropical westerly jet stream (EASWJ). At the same time, the land-sea thermal contrast between the Asian land mass and Northwest Pacific Ocean is weakened. The southward shift and increase of the EASWJ and reduction of the land-sea thermal contrast all contribute to a weakening of the EASM and EASM rainfall anomaly. [ABSTRACT FROM AUTHOR]

Early proxy-based studies suggested that there potentially occurred a 'southern drought/northern flood' (SDNF) over East China in the mid-Holocene (from roughly 7000 to 5000 years before present). In this study, we used both global and regional atmospheric circulation models to demonstrate that the SDNF-namely, the precipitation increases over North China and decreases over the the lower reaches of the Yangtze River Valley-could have taken place in the mid-Holocene. We found that the SDNF in the mid-Holocene was likely caused by the lower SST in the Pacific. The lowered SST and the higher air temperature over mainland China increased the land-sea thermal contrast and, as a result, strengthened the East Asian summer monsoon and enhanced the precipitation over North China. [ABSTRACT FROM AUTHOR]

Considering the 'Green Great Wall' project and future climate change, the vegetation in the Northwest Hetao Plain (NWHP) of China is expected to undergo considerable changes. In this study, the climatic response to prescribed changes in vegetation is investigated using the Weather Research and Forecasting model. When the vegetation is changed from 'bare or sparsely vegetated' category to 'grassland' in the NWHP, the climate shows both local and remote responses. Locally, the temperature increases in the winter but decreases in the summer. The precipitation level increases substantially in the summer while increases slightly in the winter, which is mainly caused by the increase in the amount of water-vapour and circulation adjustment. Additionally, atmospheric circulation anomalies also lead to remote circulation responses, including a decrease in precipitation over Central North China and an increase in precipitation over Central and South China. The results of this study bring to light the local and remote climatic responses to changes in vegetation in the NWHP using a state-of-the-art regional climate model. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

• Generating accurate daily precipitation data with high resolution over a large area. • The downscaling strategy effectively spatially downscales TRMM daily precipitation. • The merging scheme greatly enhances the accuracy of downscaled daily precipitation. Due to the strong variation of precipitation in time and space, it is necessary to generate accurate precipitation data with high spatiotemporal resolution. This is essential for many applications such as hydrological and meteorological analysis. However, achieving such data over a large area remains a tremendous challenge. In this study, we presented a downscaling-merging method to solve this problem. First, an integrated "temporal upscaling – spatial downscaling – temporal downscaling" strategy is introduced to spatially downscale satellite-based daily precipitation data to a high spatial resolution of 0.01°. The downscaled daily precipitation estimates are then merged with gauge observations in a multivariate geostatistical framework. To avoid the adverse effects of sparse gauges, the semivariogram model of daily precipitation is inferred from the downscaled results. The method was applied to the Tropical Rainfall Measuring Mission (TRMM) daily precipitation product covering central China's Henan Province for the period 1 January 2015–31 December 2016. The experimental results show that: (1) the downscaling strategy can effectively spatially downscale the TRMM daily precipitation product, maintaining not only the accuracy of the original TRMM data, but also providing greater spatial detail; (2) a seasonal timescale is appropriate for downscaling analysis; and (3) the merging scheme greatly enhances the accuracy of downscaled daily precipitation estimates, reducing the mean absolute error and root mean square error by 57% and 42%, respectively, and increasing the critical success index by 0.17. The proposed method provided an efficient solution for producing accurate daily precipitation data with high spatial resolution over a large area. [ABSTRACT FROM AUTHOR]