Physical Processes of Summer Extreme Rainfall Interannual Variability in Eastern China. Part I: Observational Analysis

Abstract Extreme precipitation can have catastrophic effects in China by triggering floods, landslides, and other natural disasters. We measure extreme precipitation over eastern China by the seasonal maximum of total precipitation over 5 consecutive days (Rx5day) in June, July, and August (JJA), which contributes more than 20% of the climate mean of JJA regional total precipitation. Based on the empirical orthogonal teleconnection (EOT) method, this work identifies four dominant regions of observed Rx5day interannual variability in eastern China: north-eastern China (EOT1), the southern lower reaches of the Yangtze valley (EOT2), southern China (EOT3) and the northern lower reaches of the Yangtze valley (EOT4). EOT1 extreme precipitation is related to a strong East Asian Summer Monsoon (EASM), a weak monsoon front and a northward displaced upper-tropospheric westerly jet. EOT2 and EOT4 extreme precipitation are located to the south and north of the lower reaches of the Yangtze valley, respectively. They are related to an enhanced and stable monsoon front and a strong western North Pacific subtropical high (WNPSH). The WNPSH associated with EOT4 is stronger than that associated with EOT2, which pushes the monsoon front further north. EOT3 represents extreme precipitation in southern China, related to anomalous southerlies around the western ridge of the WNPSH. The southerlies transport warm and moist air to southern China and increase precipitation there. The four key regions and the related mechanisms are not sensitive to the EOT technique, as the EOT-based extreme precipitation patterns and circulation anomalies are confirmed using Self-Organising Maps (SOMs).

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Changes in the Spatial Heterogeneity and Annual Distribution of Observed Precipitation across China

Journal of Climate ◽

10.1175/jcli-d-17-0045.1 ◽

2017 ◽

Vol 30 (23) ◽

pp. 9399-9416 ◽

Cited By ~ 19

Author(s):

Qiaohong Sun ◽

Chiyuan Miao ◽

Qingyun Duan

Keyword(s):

Extreme Precipitation ◽

Southern China ◽

Asian Summer Monsoon ◽

Eastern China ◽

Mainland China ◽

Wind Fields ◽

Spatial Variance ◽

Extreme Precipitation Events ◽

Precipitation Indices ◽

Annual Distribution

This study focuses on changing trends in the spatial variance and annual distribution of precipitation across mainland China during the period 1957–2014. The influence on precipitation of temperature, the East Asian summer monsoon (EASM), and related atmospheric circulation variables are examined to explore the underlying mechanisms driving the changes in precipitation. Statistically significant downward trends in the number of wet days were observed in humid regions. Large parts of southeastern China featured high temporal inequality of rainfall over the course of a year, with extreme precipitation events contributing a relatively large percentage of the total annual precipitation. Arid regions generally showed statistically significant upward trends in the number of wet days and in the fraction of extreme precipitation but a decrease in the temporal inequality. These spatial heterogeneities indicate that extreme precipitation became more widespread across mainland China. Temperature dominated the long-term changes in precipitation indices over large regions of mainland China, except in the Jianghuai region, where the weakening EASM induced greater precipitation and a more uneven annual distribution of precipitation. The effects of temperature on precipitation were region dependent and varied with precipitation intensity. This contributed to the overall decrease in the spatial variance of extreme precipitation and the increase in the temporal inequality of precipitation over eastern China. However, the EASM was more important for the interannual variability of precipitation indices over the west of northwestern China, the Yanghuai region, and some grids in southern China. The EASM exerted a zonal influence on precipitation variability through the modulation of water vapor patterns, wind fields, and convection activities.

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Zonal Extension and Retraction of the Subtropical Westerly Jet Stream and Evolution of Precipitation over East Asia and the Western Pacific

Journal of Climate ◽

10.1175/jcli-d-14-00649.1 ◽

2015 ◽

Vol 28 (17) ◽

pp. 6783-6798 ◽

Cited By ~ 17

Author(s):

Zhiqing Xie ◽

Yin Du ◽

Song Yang

Keyword(s):

East Asia ◽

El Nino ◽

Eastern China ◽

Jet Stream ◽

Seasonal Evolution ◽

Westerly Jet ◽

The Pacific ◽

Anomaly Pattern ◽

June July ◽

Subtropical Westerly Jet

Abstract The relationship between the zonal extension and retraction of the East Asian subtropical westerly jet stream (EASWJ) and the seasonal evolution of precipitation is investigated. The EASWJ exhibits significant zonal variations associated with its seasonal evolution, which affects both large-scale atmospheric circulation and precipitation over East Asia and the North Pacific. The midlatitude rain belts and the intertropical convergence zone are located more eastward and southward during jet extensions compared to jet retractions. The seasonal cycle of the zonal variations of EASWJ can be divided into four periods: December–February, March–May, June–July, and September–November. Particularly in the mei-yu period of June–July, jet retraction events are associated with a northward shift of rain belts over eastern China, which may play an important role in the northward movement of the mei-yu rain belt to the Huaihe River valley of eastern China after 1999. The zonal extension and retraction of the jet stream are more likely to occur in the ENSO decaying phase. A composite analysis of diabatic heating and outgoing longwave radiation shows a tripolar anomaly pattern that is strongest in El Niño winter and is important for the zonal extension of the jet stream over the Pacific. This spatial structure is conducive to a strengthening local Hadley cell over the Pacific and can also appear in weak El Niño periods. On the other hand, there is no tripolar anomaly pattern for zonally retracted jet streams.

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Reconstruction of Summer Sea Level Pressure over East Asia since 1470

Journal of Climate ◽

10.1175/jcli-d-11-00298.1 ◽

2012 ◽

Vol 25 (16) ◽

pp. 5600-5611 ◽

Cited By ~ 2

Author(s):

Fengying Wei ◽

Lei Hu ◽

Guanjun Chen ◽

Qian Li ◽

Yu Xie

Keyword(s):

East Asia ◽

Interannual Variability ◽

Sea Level ◽

Asian Summer Monsoon ◽

Eastern China ◽

Power Spectra ◽

Sea Level Pressure ◽

Level Pressure ◽

Monsoon Index ◽

Precipitation Indices

Abstract A close relationship between sea level pressure (SLP) over East Asia and precipitation indices (PIs) in eastern China was observed in the summers (June–August) of 1850–2008 using singular value decomposition (SVD) analysis. To investigate this relationship over a longer period, the SLP fields were reconstructed back to 1470 based on a mathematical model and the historical precipitation indices of eastern China. A cross-validation test of independent samples suggests that the reconstructed SLPs are statistically acceptable. According to the first three predominant SVD modes of the SLP field, three SLP index series (SLPI1–SLPI3) were developed to quantify the thermodynamic differences among the critical SLP centers of East Asia. Both SLPI1 and SLPI2 are highly correlated with the East Asian summer monsoon index, whereas SLPI3 is related to the index of Eurasian meridional atmospheric circulation. The temporal scales of SLP indices were examined during 1470–2008 using the wavelet power spectra. Results indicate that there is significant variance at a 2–5-yr band in the power spectra of the three SLP indices, suggesting SLPI1–SLPI3 have evident interannual variability. Moreover, the wavelet power spectra of SLPI1 and SLPI2 show significantly higher power at the 8–12-yr scale from 1470 to 1750 and at the 60–90-yr scale after 1750. For SLPI3, besides the interannual variability, it has additional periodical variability of 6–11 and 23–33 yr.

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Impacts of Global Warming on Meiyu-Baiu Extreme Rainfall and Associated Mid-Latitude Synoptic-Scale Systems as Inferred From 20km AGCM Simulations

10.21203/rs.3.rs-383898/v1 ◽

2021 ◽

Author(s):

Ka Wai So ◽

Chi-Yung Tam ◽

Ngar-Cheung Lau

Keyword(s):

Global Warming ◽

Extreme Precipitation ◽

General Circulation ◽

Eastern China ◽

Circulation Model ◽

Extreme Rainfall ◽

Static Stability ◽

Synoptic Scale ◽

Climate Simulations ◽

The Future

Abstract The impacts of global warming on Meiyu-Baiu extreme rainfall and the associated mid-latitude synoptic-scale weather systems over the Eastern China (EC) and the Baiu rainband (Bu) regions in East Asia have been examined, based on simulations from the 20-km Meteorological Research Institute atmospheric general circulation model (MRI-AGCM3.2S). This model was demonstrated to give realistic Asian extreme rainfall, when compared with data from the Tropical Rainfall Measuring Mission (TRMM). Here we used a novel wave-selection algorithm based on the 300hPa wind, in order to identify upper-level propagating wave signals in conjunction with the occurrence of extreme precipitation in either EC or Bu. The same algorithm was applied for both the present (1979-2003) and future (2075-2099) climate simulations from the AGCM, so as to infer the impacts of global warming on the behavior of these systems. Results show robust decrease of intensity of systems influencing both Bu and EC in the future warmer climate. Their corresponding low-to-mid level circulation, as revealed by vertical velocity, temperature advection and sea-level pressure composites, was also found to be weakened. This is likely related to changes in the background circulation in future over the East Asian mid-latitude zone, such as the widespread increment of the seasonal mean static stability at 500 hPa. However, the wave-associated precipitation over these regions was enhanced in the future climate simulations. This can be attributed to more strong intensity rainfall, which increases as the background temperature in these regions warms, largely following the Clausius-Clapeyron relation. Therefore, changes of wave-related extreme precipitation in EC and Bu are mainly controlled by the thermodynamic effect; the latter appears to be much stronger than the potential impacts due to the slight weakening of these weather systems.

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Hourly Rainfall Changes in Response to Surface Air Temperature over Eastern Contiguous China

Journal of Climate ◽

10.1175/jcli-d-11-00656.1 ◽

2012 ◽

Vol 25 (19) ◽

pp. 6851-6861 ◽

Cited By ~ 37

Author(s):

Rucong Yu ◽

Jian Li

Keyword(s):

Air Temperature ◽

Extreme Precipitation ◽

Eastern China ◽

Surface Air Temperature ◽

Late Summer ◽

Extreme Rainfall ◽

Summer Rainfall ◽

Intense Rainfall ◽

Mean Values ◽

Hourly Rainfall

Abstract In this study, late-summer rainfall over eastern contiguous China is classified according to hourly intensity and the changes of moderate, intense, and extreme precipitation in response to variation of surface air temperature are analyzed. The e-folding decay intensity (Imi) derived from the exponential distribution of rainfall amount is defined as the threshold that partitions rainfall into moderate and intense rainfall, and the double e-folding decay intensity (Ie) is used as the threshold to pick out extreme cases. The mean values of Imi and Ie are about 12 and 24 mm h−1, respectively. Between the two periods, 1966–85 and 1986–2005, the ratio between moderate and intense rainfall has experienced significant changes. And the spatial pattern of changes in the percentage of moderate rainfall presents a direct relation with that of the surface air temperature. Based on temperature changes, three regimes, regime N (north China), regime C (central eastern China), and regime S (southeastern coastal area of China), are defined. In warming regimes (regimes N and S), the percentage of moderate rainfall exhibits a decreasing trend. In regime C, where the temperature has fallen, the percentage of moderate rainfall increased prominently. In all three regimes there are significant negative (positive) correlations between the percentage of moderate (intense) rainfall and the temperature. The relation between the extreme rainfall and the surface air temperature is far more regionally dependent. With plenty of water supply and little change in relative humidity, the extreme rainfall increased in regime S. Although regime N also shows strong warming trends, there is no significant trend in extreme precipitation due to the lack of water vapor transportation.

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Combined Effects of Synoptic-Scale Teleconnection Patterns on Summer Precipitation in Southern China

10.5194/egusphere-egu2020-12374 ◽

2020 ◽

Author(s):

Chao Wang

Keyword(s):

East Asia ◽

Extreme Precipitation ◽

Southern China ◽

Summer Precipitation ◽

Western Pacific Subtropical High ◽

Asia Pacific ◽

Combined Effects ◽

Teleconnection Patterns ◽

South Asia High ◽

Westerly Jet

<p>Using ERA-Interim daily reanalysis and precipitation data, the combined effects of East Asia-Pacific (EAP) and Silk Road (SR) teleconnection patterns on summer precipitation in southern China were investigated on synoptic to sub-monthly timescales. Combined EAP and SR patterns lead to more persistent and extreme precipitation in the Yangtze River Valley (YRV) and exhibit an obvious zonal advance between the South Asia High (SAH) and Western Pacific Subtropical High (WPSH) prior to its onset. During typical combined events, an overlap between the SAH and WPSH remains in a favorable position for Persistent Extreme Precipitation (PEP). Furthermore, SR-induced acceleration of the westerly jet stream and extra positive vorticity advection provide persistent upper-level divergence for YRV precipitation. An anomalous EAP-related cyclone/anticyclone pair over East Asia induces enhanced low-level southwesterlies to the northern anticyclone flank and northerlies from the mid-latitudes, advecting anomalously abundant moisture toward the YRV, resulting in clear moisture convergence. Moreover, the strong ascent of warmer/moister air along a quasi-stationary front may be crucial for PEP. During decay, the SAH and WPSH diverge from each other and retreat to their normal positions, and the strong ascent of warmer/moister air rapidly weakens to dissipation, terminating PEP in the YRV.</p>

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Hygrophorus subsection Hygrophorus (Hygrophoraceae, Agaricales) in China

MycoKeys ◽

10.3897/mycokeys.68.53264 ◽

2020 ◽

Vol 68 ◽

pp. 49-73 ◽

Cited By ~ 1

Author(s):

Chao-Qun Wang ◽

Tai-Hui Li ◽

Ming Zhang ◽

Xiao-Lan He ◽

Wei-Qiang Qin ◽

...

Keyword(s):

New Species ◽

North America ◽

Ribosomal Rna ◽

Internal Transcribed Spacer ◽

Southern China ◽

Large Subunit ◽

Eastern China ◽

Edible Species ◽

North Eastern ◽

Its Regions

Hygrophorus subsect. Hygrophorus has been relatively well-studied in Europe and North America, but studies on the taxa in Asia, particularly in China, are still limited. In this study, phylogenetic overviews of genus Hygrophorus, based on the nuclear large subunit (LSU) ribosomal RNA gene and of subsect. Hygrophorus, based on the nuclear ribosomal internal transcribed spacer (ITS) regions were generated. Four new species, i.e. H. brunneodiscus, H. fuscopapillatus, H. glutiniceps and H. griseodiscus are described from southern China; and a rarely reported edible species H. hedrychii is described in detail, based upon the materials from north-eastern China. The main characteristics of the species under subsect. Hygrophorus worldwide are summarised in a table.

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Simulation study on the indirect effect of sulfate on the summer climate over the eastern China monsoon region

Scientific Reports ◽

10.1038/s41598-021-87832-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Dongdong Wang ◽

Bin Zhu ◽

Hongbo Wang ◽

Li Sun

Keyword(s):

Radiative Forcing ◽

Asian Summer Monsoon ◽

Cloud Condensation Nuclei ◽

Eastern China ◽

Summer Precipitation ◽

Cloud Droplet ◽

Monsoon Region ◽

Liquid Water Path ◽

Surface Cooling ◽

Community Atmosphere Model

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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Factors affecting health care users’ first contact with primary health care facilities in north eastern China, 2008–2018

BMJ Global Health ◽

10.1136/bmjgh-2020-003907 ◽

2021 ◽

Vol 6 (2) ◽

pp. e003907

Author(s):

Ran Liao ◽

Yaqian Liu ◽

Shunzhuang Peng ◽

Xing Lin Feng

Keyword(s):

Health Care ◽

Primary Health Care ◽

Eastern China ◽

Medical System ◽

Health Care Facilities ◽

Factors Affecting ◽

Primary Health ◽

North Eastern ◽

First Contact ◽

Hierarchical Medical System

BackgroundChina set out the vision to establishing a hierarchical medical system, with primary health care (PHC) facilities serving health care users’ first contact. Common ailments were listed, supported by a series of auxiliary policy measures. We aim to assess whether these policies were effective to prompt users’ preference to PHCs within these contexts.MethodsUsing data from three waves of National Health Service Survey, we examined trends in care users’ first contact with PHC facilities in Jilin, a north eastern province, during 2008–2018. We analysed trends and factors affecting care users’ choices, stratified by type of diseases and urban–rural settings.ResultsFrom 38 823 respondents, the survey identified 3302 health care users who sought outpatient care. 54.92% and 82.49% with diseases recommended to PHC, in urban and rural Jilin, respectively, contacted PHC facilities first. While 33.51% and 61.19% with diseases not recommended to PHC did so. Care users’ first contact with PHC facilities followed an inverse U shape during 2008–2018. Such trends were more profound among care users with hypertension and/or diabetes. Neither social health insurance coverage nor contracting with family doctors was associated with care users’ first contacts. Only 1.25% care users had referral experiences. Low perceived quality was the main barrier to choose PHC facilities.ConclusionHealth care users sought PHC in a chaotic manner in Jilin. None of the recent efforts seemed effective in prompting their preference to PHC facilities. Without levering quality of PHC, an effective hierarchical medical system could be hardly forged in China.

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Spatial and Temporal Characteristics of Environmental Air Quality and Its Relationship with Seasonal Climatic Conditions in Eastern China during 2015–2018

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18094524 ◽

2021 ◽

Vol 18 (9) ◽

pp. 4524

Author(s):

Zhiyuan Wang ◽

Xiaoyi Shi ◽

Chunhua Pan ◽

Sisi Wang

Keyword(s):

Particulate Matter ◽

Air Quality ◽

Air Pollutants ◽

Large Scale ◽

Asian Summer Monsoon ◽

Eastern China ◽

Climatic Conditions ◽

Uniform Structure ◽

Concentration Limit ◽

Environmental Air

Exploring the relationship between environmental air quality (EAQ) and climatic conditions on a large scale can help better understand the main distribution characteristics and the mechanisms of EAQ in China, which is significant for the implementation of policies of joint prevention and control of regional air pollution. In this study, we used the concentrations of six conventional air pollutants, i.e., carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), fine particulate matter (PM2.5), coarse particulate matter (PM10), and ozone (O3), derived from about 1300 monitoring sites in eastern China (EC) from January 2015 to December 2018. Exploiting the grading concentration limit (GB3095-2012) of various pollutants in China, we also calculated the monthly average air quality index (AQI) in EC. The results show that, generally, the EAQ has improved in all seasons in EC from 2015 to 2018. In particular, the concentrations of conventional air pollutants, such as CO, SO2, and NO2, have been decreasing year by year. However, the concentrations of particulate matter, such as PM2.5 and PM10, have changed little, and the O3 concentration increased from 2015 to 2018. Empirical mode decomposition (EOF) was used to analyze the major patterns of AQI in EC. The first mode (EOF1) was characterized by a uniform structure in AQI over EC. These phenomena are due to the precipitation variability associated with the East Asian summer monsoon (EASM), referred to as the “summer–winter” pattern. The second EOF mode (EOF2) showed that the AQI over EC is a north–south dipole pattern, which is bound by the Qinling Mountains and Huaihe River (about 35° N). The EOF2 is mainly caused by seasonal variations of the mixed concentration of PM2.5 and O3. Associated with EOF2, the Mongolia–Siberian High influences the AQI variation over northern EC by dominating the low-level winds (10 m and 850 hPa) in autumn and winter, and precipitation affects the AQI variation over southern EC in spring and summer.

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