Land-air interaction over arid/semi-arid areas in China and its impact on the east Asian summer monsoon. Part I: Calibration of the land surface model (BATS) using multicriteria methods

Abstract. The response of East Asian Summer Monsoon (EASM) precipitation to long term changes in regional anthropogenic aerosols (sulphate and black carbon) is explored in an atmospheric general circulation model, the atmospheric component of the UK High-Resolution Global Environment Model v1.2 (HiGAM). Separately, sulphur dioxide (SO2) and black carbon (BC) emissions in 1950 and 2000 over East Asia are used to drive model simulations, while emissions are kept constant at year 2000 level outside this region. The response of the EASM is examined by comparing simulations driven by aerosol emissions representative of 1950 and 2000. The aerosol radiative effects are also determined using an off-line radiative transfer model. During June, July and August, the EASM was not significantly changed as either SO2 or BC emissions increased from 1950 to 2000 levels. However, in September, precipitation is significantly decreased by 26.4% for sulphate aerosol and 14.6% for black carbon when emissions are at the 2000 level. Over 80% of the decrease is attributed to changes in convective precipitation. The cooler land surface temperature over China in September (0.8 °C for sulphate and 0.5 °C for black carbon) due to increased aerosols reduces the surface thermal contrast that supports the EASM circulation. However, mechanisms causing the surface temperature decrease in September are different between sulphate and BC experiments. In the sulphate experiment, the sulphate direct and the 1st indirect radiative effects contribute to the surface cooling. In the BC experiment, the BC direct effect is the main driver of the surface cooling, however, a decrease in low cloud cover due to the increased heating by BC absorption partially counteracts the direct effect. This results in a weaker land surface temperature response to BC changes than to sulphate changes. The resulting precipitation response is also weaker, and the responses of the monsoon circulation are different for sulphate and black carbon experiments. This study demonstrates a mechanism that links regional aerosol emission changes to the precipitation changes of the EASM, and it could be applied to help understand the future changes in EASM precipitation in CMIP5 simulations.

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Effects of Nonuniform Land Surface Warming on Summer Anomalous Extratropical Cyclone Activity and the East Asian Summer Monsoon: Numerical Experiments with a Regional Climate Model

Journal of Climate ◽

10.1175/jcli-d-20-0088.1 ◽

2020 ◽

Vol 33 (24) ◽

pp. 10469-10488

Author(s):

Wanxin Zhang ◽

Haishan Chen ◽

Liming Zhou ◽

Botao Zhou ◽

Jie Zhang ◽

...

Keyword(s):

East Asia ◽

Land Surface ◽

East Asian Summer Monsoon ◽

Climate Model ◽

Asian Summer Monsoon ◽

Regional Climate ◽

East Asian ◽

Anticyclonic Circulation ◽

Surface Warming ◽

Asian Summer

AbstractPrevious studies detected significant negative correlations between the nonuniform land surface warming and the decadal weakened activities of the summer extratropical cyclones (ECs) over East Asia and the East Asian summer monsoon (EASM) after the early 1990s. Here such relationships are further examined and the possible mechanisms are explored via numerical sensitivity experiments with a regional climate model (RegCM4.5). The positive/negative sensible heat flux (SH) anomalies were added as a forcing to a key region near 50°N of East Asia in RegCM4.5 to simulate the observed ground surface temperature (GST) anomalies. The model results suggest that the nonuniform land surface warming over the Lake Baikal area (50°–60°N, 90°–120°E) can indeed cause the weakening of the extratropical cyclogenesis and affect the decadal weakening of the EASM. Warm (cold) GST forcing over the key GST region can lead to decreasing (increasing) atmospheric baroclinicity and related energy conversion of the EC activity over the key EC region (40°–50°N, 90°–120°E), resulting in an evidently weakening (enhancing) of the ECs over East Asia. Meanwhile, precipitation shows a dipole pattern with significantly suppressed (enhanced) precipitation in northern and northeastern China, and slightly enhanced (suppressed) rainfall south of 40°N of East Asia, mainly over the East China Sea. Lake Baikal and its adjacent areas are occupied by a strong anticyclonic (cyclonic) circulation while the southeast coastal areas of China have a relatively weak cyclonic (anticyclonic) circulation accompanied with an anomalous northeasterly (southwesterly) wind to the southeast of the anticyclonic circulation, which is opposite to (coincident with) the atmospheric circulation anomalies that are associated with the second mode of the EASM.

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The effect of regional changes in anthropogenic aerosols on rainfall of the East Asian Summer Monsoon

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-23007-2012 ◽

2012 ◽

Vol 12 (9) ◽

pp. 23007-23038 ◽

Cited By ~ 6

Author(s):

L. Guo ◽

E. J. Highwood ◽

L. C. Shaffrey ◽

A. G. Turner

Keyword(s):

Surface Temperature ◽

Black Carbon ◽

Land Surface Temperature ◽

Land Surface ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Surface Cooling ◽

Anthropogenic Aerosols ◽

Asian Summer

Abstract. The response of East Asian Summer Monsoon (EASM) precipitation to long term changes in regional anthropogenic aerosols (sulphate and black carbon) is explored in an atmospheric general circulation model, the atmospheric component of the UK High-Resolution Global Environment Model v1.2 (HiGAM). Separately, sulphur dioxide (SO2) and black carbon (BC) emissions in 1950 and 2000 over East Asia are used to drive model simulations, while emissions are kept constant at year 2000 level outside this region. The response of the EASM is examined by comparing simulations driven by aerosol emissions representative of 1950 and 2000. The aerosol radiative effects are also determined using an off-line radiative transfer model. During June, July and August, the EASM was not significantly changed as either SO2 or BC emissions increased from 1950 to 2000 levels. However, in September, precipitation is significantly decreased when emissions are at the 2000 level. The cooler land surface temperature over China in September due to increased aerosols reduces the surface thermal contrast that supports the EASM circulation. However, mechanisms causing the surface temperature decrease in September are different between sulphate and BC experiments. In the sulphate experiment, the sulphate direct and the 1st indirect radiative effects contribute to the surface cooling. In the BC experiment, the BC direct effect is the main driver of the surface cooling, however, a decrease in low cloud cover due to the increased heating by BC absorption partially counteracts the direct effect. This results in a weaker land surface temperature response to BC changes than to sulphate changes. The resulting precipitation response is also weaker, and the responses of the monsoon circulation are different for sulphate and black carbon experiments. This study demonstrates a mechanism that links regional aerosol emission changes to the precipitation changes of the EASM, and it could be applied to help understand the future changes in EASM precipitation in CMIP5 simulations.

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An assessment of the land surface parameters on the simulated regional climate circulations: The 1997 and 1998 east Asian summer monsoon cases

Journal of Geophysical Research Atmospheres ◽

10.1029/2007jd009499 ◽

2008 ◽

Vol 113 (D15) ◽

Cited By ~ 14

Author(s):

Hyun-Suk Kang ◽

Song-You Hong

Keyword(s):

Summer Monsoon ◽

Land Surface ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

Regional Climate ◽

East Asian ◽

Surface Parameters ◽

Asian Summer ◽

Land Surface Parameters

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The effects of land-surface characteristics on the East Asian summer monsoon

Climate Dynamics ◽

10.1007/s003820000115 ◽

2001 ◽

Vol 17 (4) ◽

pp. 317-326 ◽

Cited By ~ 7

Author(s):

R.-Y. Tzeng ◽

Y.-H. Lee

Keyword(s):

Summer Monsoon ◽

Land Surface ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Surface Characteristics ◽

Asian Summer ◽

Land Surface Characteristics

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Impacts of Anomalous Midlatitude Cyclone Activity over East Asia during Summer on the Decadal Mode of East Asian Summer Monsoon and Its Possible Mechanism

Journal of Climate ◽

10.1175/jcli-d-16-0155.1 ◽

2017 ◽

Vol 30 (2) ◽

pp. 739-753 ◽

Cited By ~ 13

Author(s):

Haishan Chen ◽

Fangda Teng ◽

Wanxin Zhang ◽

Hong Liao

Keyword(s):

East Asia ◽

Summer Monsoon ◽

Land Surface ◽

East Asian Summer Monsoon ◽

Asian Summer Monsoon ◽

East Asian ◽

Cyclone Activity ◽

Asian Summer ◽

The Impact ◽

Decadal Mode

By using an objective identification and tracking algorithm of the cyclone, the statistics of midlatitude cyclone activity in East Asia during summer for the period 1979–2013 were analyzed. The impact of the midlatitude summer cyclone anomalies in East Asia on the decadal mode of East Asian summer monsoon (EASM) was investigated and possible mechanisms were proposed. The possible reasons for the anomalous cyclone activity from the perspective of land surface thermal forcing were also explored. Results indicate that the midlatitude summer cyclone activity over East Asia exhibits decadal changes in the period of 1979–2013 and is significantly weakened after early 1990s. Further analysis indicates that there is a close relationship between the midlatitude summer cyclone activity over East Asia and the decadal variation of EASM; when the midlatitude summer cyclone activity over East Asia is strong (weak), EASM tends to be intensified (weakened), and the weak cyclone activity after 1993 generally coincides with the decadal weakening of EASM. Moreover, there is a close linkage between the weakening of cyclonic activity after the early 1990s and the nonuniform surface warming of the Eurasian continent. Significant warming to the west of Mongolia tends to weaken the north–south temperature gradient and the atmospheric baroclinicity to its south and eventually can lead to weakening of the midlatitude cyclone activity over East Asia.

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