Evolution of Large-Scale Circulation and Heating during the First Transition of Asian Summer Monsoon

Hsu, Huang‐Hsiung; Terng, Chuen Teyr; Chen, Cheng Ta

doi:10.1175/1520-0442(1999)012<0793:eolsca>2.0.co;2

Cited by 109 publications

(117 citation statements)

References 12 publications

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“…Therefore, the variation of SASM index in the HEST2006 campaign mainly presents a break stage and an active stage of SASM, on June 8 -21 and 22-29, with persistent and large negative and positive values, respectively. As an indicator for the monsoon evolution [e.g., Lau and Yang, 1997;Hsu et al, 1999;Webster et al, 1998], the variation of zonal wind at 10°N at 850 hPa additionally coincides the active and break stages in the SASM evolution.…”

Section: Sasmmentioning

confidence: 99%

Study on impact of the South Asian summer monsoon on the down‐valley wind on the northern slope of Mt. Everest

Zhou

Han

2008

Geophysical Research Letters

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Based on the observational data from the HEST2006 campaign in the Rongbuk Valley on the northern slope of Mt. Everest, in June, 2006, the variation of surface wind in the Rongbuk Valley and possible impact of the South Asian summer monsoon (SASM) on the surface wind are analyzed. During the observation campaign, SASM experienced a break stage and an active stage in middle and late June, 2006, respectively. The surface wind variation measured in the Rongbuk Valley is closely related to the SASM evolution, with a strong down‐valley wind coinciding with the break stage of SASM and a weak down‐valley wind with the active stage. It is suggested that the impact of SASM on the surface wind on the northern slope of Mt. Everest can be attributed to change of radiation conditions.

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Section: Sasmmentioning

confidence: 99%

Study on impact of the South Asian summer monsoon on the down‐valley wind on the northern slope of Mt. Everest

Zhou

Han

2008

Geophysical Research Letters

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“…It is important for a regional climate model to be able to simulate the timing and major characteristics of the onset. Hsu et al (1999) reported that the EASM onset often occurred concurrently with the first transition of the Asian summer monsoon. This relationship was also observed in the 1998 EASM (Ding and Liu 2001).…”

Section: Easm Onset and High Frequency Variationmentioning

confidence: 99%

Simulation of the 1998 East Asian Summer Monsoon using the Purdue Regional Model

Hsu

Kau

et al. 2004

Journal of the Meteorological Society of Japan

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This study used the Purdue Regional Model to simulate the 1998 EASM to assess the model performance. The results indicated that the model was capable of simulating the overall characteristics of the 1998 EASM on the seasonal, intraseasonal, onset, and daily time scales. On the seasonal time scale, the model tended to produce more precipitation over the land and less precipitation over the ocean. This land-sea contrast in the model performance was consistent with the stronger-than-observed Pacific anticyclone in the simulation. It appears that the over simulated anticyclone was also found in other models, and is not a unique problem to the PRM. Future studies are needed to tackle this seemingly fundamental problem in several regional models.The model simulated the seasonal march of the EASM well, characterized by northward-propagating rain bands. Intraseasonal oscillation events propagating northward were also well reproduced. These results confirm that the model is capable of producing realistic sub-seasonal variability in the inner domain, once the proper lateral boundary forcing is provided.The model correctly simulated the onset timing and dramatic changes before and after the onset. However, the model incorrectly simulated the circulation and precipitation during the onset, because it failed to simulate the rapid development of a weak trough in the northern South China Sea. After the onset period, the model performance became reliable again. This indicates that the model is capable of fixing the existing large biases, with the proper lateral boundary forcing.This model was able to simulate the gross fluctuation in the regional-averaged daily precipitation, although it missed some extreme events that resulted in flooding in China. The incorrect simulation of these extreme events was partially responsible for the biases in the simulated seasonal precipitation. It is suggested that a regional model should be able to simulate the multi-scale features from the daily to seasonal time scales and their mutual interaction to correctly simulate the monthly and seasonal mean fields.

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“…The temperature differences between the Asian landmass, especially the Tibetan Plateau, and the Indian Ocean, drive a cyclonic circulation over the Indian Ocean at low altitudes (Hoskins and Rodwell, 1995;Hsu et al, 1999). At the same time, during the summer monsoon period an anticyclone develops in the upper troposphere (Krishnamurti and Bhalme, 1976).…”

Section: Introductionmentioning

confidence: 99%

Greenhouse gas relationships in the Indian summer monsoon plume measured by the CARIBIC passenger aircraft

et al. 2010

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Abstract. During the Indian summer monsoon period 2008, regular measurement flights were performed by the CARIBIC aircraft between Germany and India. Measurements included whole air sampling and subsequent analysis for greenhouse gases (CH 4 , CO 2 , N 2 O, SF 6 ) and in-situ measurements of CO, O 3 , and H 2 O. For all these tracers a distinct monsoon signature was observed in the longitude range 50-80 • E south of 40 • N at flight altitudes 8-12.5 km. The formation of a monsoon plume with enhanced mixing ratios was observed for CH 4 , N 2 O, SF 6 , CO and H 2 O. The plume began to develop in May and persisted through September, and maximum mixing ratios and maximum spatial extension of the plume were observed in August. For CO 2 and O 3 a minimum was observed. The amplitude of the CO 2 seasonal cycle was larger than at comparable latitudes outside the monsoon region, and the CO 2 spring maximum was observed with a delay of one month. Different tracer relationships show strong spatial variations across the plume. The comparison with NOAA ground station data shows a clear enhancement for CH 4 , N 2 O, SF 6 and CO and a decrease in CO 2 mixing ratios. Assuming seasonally invariant SF 6 emissions based on the EDGAR 4.0 inventory, monthly emissions were estimated for the period June-September for CH 4 , N 2 O, and CO, and the CO 2 uptake was estimated. While for N 2 O an emission decrease during the monsoon period was derived, emissions of CH 4 were highest in September indicating a different seasonal cycle of emissions. Net CO 2 uptake by the vegetation was largest in September.

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Evolution of Large-Scale Circulation and Heating during the First Transition of Asian Summer Monsoon

Cited by 109 publications

References 12 publications

Study on impact of the South Asian summer monsoon on the down‐valley wind on the northern slope of Mt. Everest

Study on impact of the South Asian summer monsoon on the down‐valley wind on the northern slope of Mt. Everest

Simulation of the 1998 East Asian Summer Monsoon using the Purdue Regional Model

Greenhouse gas relationships in the Indian summer monsoon plume measured by the CARIBIC passenger aircraft

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