Contribution of Changes in Synoptic‐Scale Circulation Patterns to the Past Summer Precipitation Regime Shift in Eastern China

Abstract. We use measurements of recent decades, 1500-yr proxy data, and millennium model simulations with a variety of climate facings to study the temporal and spatial variability of summer precipitation over eastern China. Spectral analysis of the proxy data using multi-taper method reveals three statistically significant bidecadal (15–35-yr), pendadecadal (40–60-yr), and centennial (65–170-yr) oscillation bands. The results of wavelet filtering show that the amplitudes of these bands vary substantially through time depending on the temperature regimes. Weak centennial oscillation and strong pentadecadal oscillation occur in warm conditions, whereas both the centennial and pentadecadal oscillations are strong in cold conditions. A model/data intercomparison suggests that pentadecadal and bidecadal oscillations could be associated with internal variability of the climate system. It is also found that the increased frequency of drought-in-north/flood-in-south spatial pattern over eastern China during the last two decades is unusual in the past five centuries.

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Variability of summer precipitation over eastern China during the last millennium

Climate of the Past Discussions ◽

10.5194/cpd-4-611-2008 ◽

2008 ◽

Vol 4 (3) ◽

pp. 611-643 ◽

Cited By ~ 4

Author(s):

C. Shen ◽

W.-C. Wang ◽

Y. Peng ◽

Y. Xu ◽

J. Zheng

Keyword(s):

Eastern China ◽

Summer Precipitation ◽

Internal Variability ◽

Model Data ◽

Solar Forcing ◽

Proxy Data ◽

The Past ◽

Temperature Regimes ◽

Temporal And Spatial Variability ◽

Temporal And Spatial

Abstract. We use measurements of recent decades, 1500-yr proxy data, and millennium model simulations with a variety of climate facings to study the temporal and spatial variability of summer precipitation over eastern China. Spectral analysis of the proxy data using multi-taper method reveals three statistically significant bidecadal (15–35-yr), pendadecadal (40–60-yr), and centennial (65–170-yr) oscillation bands. The results of wavelet filtering show that the amplitudes of these bands vary substantially through time depending on the temperature regimes. Weak centennial oscillation and strong pentadecadal oscillation occur in warm conditions, whereas the oscillations are both strong in cold conditions. A model/data intercomparison suggests that the centennial oscillation might be linked to the fluctuation of solar forcing (Gleissberg cycle), and the pentadecadal and bidecadal oscillations could be associated with internal variability of the climate system. It is also found that the increased frequency of drought-in-north/flood-in-south spatial pattern over eastern China during the last two decades is unusual in the past five centuries.

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Atmospheric Circulation Patterns over East Asia and Their Connection with Summer Precipitation and Surface Air Temperature in Eastern China during 1961–2013

Journal of Meteorological Research ◽

10.1007/s13351-018-7071-4 ◽

2018 ◽

Vol 32 (2) ◽

pp. 203-218 ◽

Cited By ~ 5

Author(s):

Shuping Li ◽

Wei Hou ◽

Guolin Feng

Keyword(s):

East Asia ◽

Atmospheric Circulation ◽

Air Temperature ◽

Eastern China ◽

Surface Air Temperature ◽

Summer Precipitation ◽

Atmospheric Circulation Patterns ◽

Circulation Patterns

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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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Monitoring Changes in the Transparency of the Largest Reservoir in Eastern China in the Past Decade, 2013–2020

Remote Sensing ◽

10.3390/rs13132570 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2570

Author(s):

Teng Li ◽

Bozhong Zhu ◽

Fei Cao ◽

Hao Sun ◽

Xianqiang He ◽

...

Keyword(s):

Remote Sensing ◽

Mean Squared Error ◽

Eastern China ◽

Water Environment ◽

Relative Difference ◽

Boreal Summer ◽

Support Vector ◽

Lake Area ◽

The Past ◽

Remote Sensing Reflectance

Based on characteristics analysis about remote sensing reflectance, the Secchi Disk Depth (SDD) in the Qiandao Lake was predicted from the Landsat8/OLI data, and its changing rates on a pixel-by-pixel scale were obtained from satellite remote sensing for the first time. Using 114 matchups data pairs during 2013–2019, the SDD satellite algorithms suitable for the Qiandao Lake were obtained through both the linear regression and machine learning (Support Vector Machine) methods, with remote sensing reflectance (Rrs) at different OLI bands and the ratio of Rrs (Band3) to Rrs (Band2) as model input parameters. Compared with field observations, the mean absolute relative difference and root mean squared error of satellite-derived SDD were within 20% and 1.3 m, respectively. Satellite-derived results revealed that SDD in the Qiandao Lake was high in boreal spring and winter, and reached the lowest in boreal summer, with the annual mean value of about 5 m. Spatially, high SDD was mainly concentrated in the southeast lake area (up to 13 m) close to the dam. The edge and runoff area of the lake were less transparent, with an SDD of less than 4 m. In the past decade (2013–2020), 5.32% of Qiandao Lake witnessed significant (p < 0.05) transparency change: 4.42% raised with a rate of about 0.11 m/year and 0.9% varied with a rate of about −0.09 m/year. Besides, the findings presented here suggested that heavy rainfall would have a continuous impact on the Qiandao Lake SDD. Our research could promote the applications of land observation satellites (such as the Landsat series) in water environment monitoring in inland reservoirs.

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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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Ozone formation under low solar radiation in eastern China

10.5194/acp-2019-354 ◽

2019 ◽

Author(s):

Xuexi Tie ◽

Xin Long ◽

Guohui Li ◽

Shuyu Zhao ◽

Jianming Xu

Keyword(s):

Solar Radiation ◽

Eastern China ◽

Threshold Level ◽

Radiative Transfer Model ◽

Transfer Model ◽

Oh Radicals ◽

Chemical Production ◽

The Past ◽

Photochemical Production ◽

Steady State Model

Abstract. PM2.5, a particulate matter with a diameter of 2.5 micrometers or less, is one of the major components of the air pollution in eastern China. In the past few years, China's government made strong efforts to reduce the PM2.5 pollutions. However, another important pollutant (ozone) becomes an important problem in eastern China. Ozone (O3) is produced by photochemistry, which requires solar radiation for the formation of O3. Under heavy PM2.5 pollution, the solar radiation is often depressed, and the photochemical production of O3 is prohibited. This study shows that during fall in eastern China, under heavy PM2.5 pollutions, there were often strong O3 photochemical productions, causing a co-occurrence of high PM2.5 and O3 concentrations. This co-occurrence of high PM2.5 and O3 is un-usual and is the main focus of this study. Recent measurements show that there were often high HONO surface concentrations in major Chinese mega cities, especially during daytime, with maximum concentrations ranging from 0.5 to 2 ppbv. It is also interesting to note that the high HONO concentrations were occurred during high aerosol concentration periods, suggesting that there were additional HONO surface sources in eastern China. Under the high daytime HONO concentrations, HONO can be photo-dissociated to be OH radicals, which enhance the photochemical production of O3. In order to study the above scientific issues, a radiative transfer model (TUV; Tropospheric Ultraviolet-Visible) is used in this study, and a chemical steady state model is established to calculate OH radical concentrations. The calculations show that by including the OH production of the photo-dissociated of HONO, the calculated OH concentrations are significantly higher than the values without including this production. For example, by including HONO production, the maximum of OH concentration under the high aerosol condition (AOD = 2.5) is similar to the value under low aerosol condition (AOD = 0.25) in the no-HONO case. This result suggests that even under the high aerosol condition, the chemical oxidizing process for O3 production can occurred, which explain the co-occurrence of high PM2.5 and high O3 in fall season in eastern China. However, the O3 concentrations were not significantly affected by the appearance of HONO in winter. This study shows that the seasonal variation of solar radiation plays important roles for controlling the OH production in winter. When the solar radiation is in a very low level in winter, it reaches the threshold level to prevent the OH chemical production, even by including the HONO production of OH. This study provides some important scientific highlights to better understand the O3 pollutions in eastern China.

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A note on some further determinations of the dielectric constants of organic bodies and electrolytes at very low temperatures

Proceedings of the Royal Society of London ◽

10.1098/rspl.1897.0105 ◽

1898 ◽

Vol 62 (379-387) ◽

pp. 250-266 ◽

Cited By ~ 4

Keyword(s):

Dielectric Constant ◽

Low Temperatures ◽

Tuning Fork ◽

Dielectric Constants ◽

The Past ◽

Method Of Measurement ◽

The Given ◽

Past Summer

In several previous communications we have described the investigations made by us on the dielectric constants of various frozen organic bodies and electrolytes at very low temperatures. In these researches we employed a method for the measurement of the dielectric constant which consisted in charging and discharging a condenser, having the given body as dielectric, through a galvanometer 120 times in a second by means of a tuning-fork interrupter. During the past summer we have repeated some of these determinations and used a different method of measurement and a rather higher frequency. In the experiments here described we have adopted Nernst’s method for the measurement of dielectric constants, using for this purpose the apparatus as arranged by Dr. Nernst which belongs to the Davy-Faraday Laboratory.

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VIII. Account of experiments on torsion and flexure for the determination of rigidities

Philosophical Transactions of the Royal Society of London ◽

10.1098/rstl.1867.0008 ◽

1867 ◽

Vol 157 ◽

pp. 139-153 ◽

Cited By ~ 1

Keyword(s):

The Past ◽

Past Summer

In my Paper read February 22nd, 1866, the intention was expressed of continuing my experiments on rigidity with a modified form of apparatus. This intention was carried out during the past summer, and I have now to report the results. In the former experiments, the rod operated on was supported at both ends, and was bent or twisted by hanging a pair of equal weights so as to act symmetrically on both ends; and the amounts of flexure and torsion were measured by the movements of two images formed by reflection upon a screen.

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