How Do Extreme Summer Precipitation Events Over Eastern China Subregions Change?

AbstractIn this study, we designed a sensitivity test using the half number concentration of sulfate in the nucleation calculation process to study the aerosol-cloud interaction (ACI) of sulfate on clouds, precipitation, and monsoon intensity in the summer over the eastern China monsoon region (ECMR) with the National Center for Atmospheric Research Community Atmosphere Model version 5. Numerical experiments show that the ACI of sulfate led to an approximately 30% and 34% increase in the cloud condensation nuclei and cloud droplet number concentrations, respectively. Cloud droplet effective radius below 850 hPa decreased by approximately 4% in the southern ECMR, while the total liquid water path increased by 11%. The change in the indirect radiative forcing due to sulfate at the top of the atmosphere in the ECMR during summer was − 3.74 W·m−2. The decreased radiative forcing caused a surface cooling of 0.32 K and atmospheric cooling of approximately 0.3 K, as well as a 0.17 hPa increase in sea level pressure. These changes decreased the thermal difference between the land and sea and the gradient of the sea-land pressure, leading to a weakening in the East Asian summer monsoon (EASM) and a decrease in the total precipitation rate in the southern ECMR. The cloud lifetime effect has a relatively weaker contribution to summer precipitation, which is dominated by convection. The results show that the ACI of sulfate was one possible reason for the weakening of the EASM in the late 1970s.

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Recognizing the Aggregation Characteristics of Extreme Precipitation Events Using Spatio-Temporal Scanning and the Local Spatial Autocorrelation Model

Atmosphere ◽

10.3390/atmos12020218 ◽

2021 ◽

Vol 12 (2) ◽

pp. 218

Author(s):

Changjun Wan ◽

Changxiu Cheng ◽

Sijing Ye ◽

Shi Shen ◽

Ting Zhang

Keyword(s):

Spatial Autocorrelation ◽

Extreme Precipitation ◽

Eastern China ◽

Temporal Aggregation ◽

Global Changes ◽

Percentile Method ◽

Extreme Precipitation Events ◽

Spatio Temporal ◽

Precipitation Events ◽

Local Spatial Autocorrelation

Precipitation is an essential climate variable in the hydrologic cycle. Its abnormal change would have a serious impact on the social economy, ecological development and life safety. In recent decades, many studies about extreme precipitation have been performed on spatio-temporal variation patterns under global changes; little research has been conducted on the regionality and persistence, which tend to be more destructive. This study defines extreme precipitation events by percentile method, then applies the spatio-temporal scanning model (STSM) and the local spatial autocorrelation model (LSAM) to explore the spatio-temporal aggregation characteristics of extreme precipitation, taking China in July as a case. The study result showed that the STSM with the LSAM can effectively detect the spatio-temporal accumulation areas. The extreme precipitation events of China in July 2016 have a significant spatio-temporal aggregation characteristic. From the spatial perspective, China’s summer extreme precipitation spatio-temporal clusters are mainly distributed in eastern China and northern China, such as Dongting Lake plain, the Circum-Bohai Sea region, Gansu, and Xinjiang. From the temporal perspective, the spatio-temporal clusters of extreme precipitation are mainly distributed in July, and its occurrence was delayed with an increase in latitude, except for in Xinjiang, where extreme precipitation events often take place earlier and persist longer.

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Roles of anthropogenic forcings in the observed trend of decreasing late-summer precipitation over the East Asian transitional climate zone

Scientific Reports ◽

10.1038/s41598-021-84470-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Wei Zhao ◽

Wen Chen ◽

Shangfeng Chen ◽

Hainan Gong ◽

Tianjiao Ma

Keyword(s):

Asian Summer Monsoon ◽

Dominant Role ◽

East Asian ◽

Eastern China ◽

Summer Precipitation ◽

Late Summer ◽

Water Vapor Transport ◽

Anthropogenic Aerosol ◽

Climate Zone ◽

Drying Trend

AbstractObservations indicate that late-summer precipitation over the East Asian transitional climate zone (TCZ) showed a pronounced decreasing trend during 1951–2005. This study examines the relative contributions of anthropogenic [including anthropogenic aerosol (AA) and greenhouse gas (GHG)] and natural forcings to the drying trend of the East Asian TCZ based on simulations from CMIP5. The results indicate that AA forcing plays a dominant role in contributing to the drying trend of the TCZ. AA forcing weakens the East Asian summer monsoon via reducing the land-sea thermal contrast, which induces strong low-level northerly anomalies over eastern China, suppresses water vapor transport from southern oceans and results in drier conditions over the TCZ. In contrast, GHG forcing leads to a wetting trend in the TCZ by inducing southerly wind anomalies, thereby offsetting the effect of the AA forcing. Natural forcing has a weak impact on the drying trend of the TCZ due to the weak response of atmospheric anomalies.

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Numerical study of effects of synoptic‐scale disturbances at high and low latitudes on mean summer precipitation over north‐eastern China and the Tibetan Plateau

International Journal of Climatology ◽

10.1002/joc.7093 ◽

2021 ◽

Author(s):

Chenyu Wang ◽

Suxiang Yao

Keyword(s):

Tibetan Plateau ◽

Numerical Study ◽

Eastern China ◽

Summer Precipitation ◽

The Tibetan Plateau ◽

Synoptic Scale ◽

North Eastern ◽

Low Latitudes

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Detectable Anthropogenic Influence on Changes in Summer Precipitation in China

Journal of Climate ◽

10.1175/jcli-d-19-0285.1 ◽

2020 ◽

Vol 33 (13) ◽

pp. 5357-5369

Author(s):

Chunhui Lu ◽

Fraser C. Lott ◽

Ying Sun ◽

Peter A. Stott ◽

Nikolaos Christidis

Keyword(s):

Human Life ◽

Eastern China ◽

Precipitation Amount ◽

Summer Precipitation ◽

Heavy Precipitation ◽

Observation Data ◽

Anthropogenic Influence ◽

Anthropogenic Forcing ◽

The Future ◽

Light Precipitation

AbstractIn China, summer precipitation contributes a major part of the total precipitation amount in a year and has major impacts on society and human life. Whether any changes in summer precipitation are affected by external forcing on the climate system is an important issue. In this study, an optimal fingerprinting method was used to compare the observed changes of total, heavy, moderate, and light precipitation in summer derived from newly homogenized observation data with the simulations from multiple climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5). The results demonstrate that the anthropogenic forcing signal can be detected and separated from the natural forcing signal in the observed increase of seasonal accumulated precipitation amount for heavy precipitation in summer in China and eastern China (EC). The simulated changes in heavy precipitation are generally consistent with observed change in China but are underestimated in EC. When the changes in precipitation of different intensities are considered simultaneously, the human influence on simultaneous changes in moderate and light precipitation can be detected in China and EC in summer. Changes attributable to anthropogenic forcing explain most of the observed regional changes for all categories of summer precipitation, and natural forcing contributes little. In the future, with increasing anthropogenic influence, the attribution-constrained projection suggests that heavy precipitation in summer will increase more than that from the model raw outputs. Society may therefore face a higher risk of heavy precipitation in the future.

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