HR: 0800h
AN: GC21A-0132    [Abstracts]
TI: South Asian Summer Monsoon Dynamics In A High-Resolution Nested Climate Model
AU: * Ashfaq, M
EM: mashfaq@purdue.edu
AF: Purdue Climate Change Research Center and Department of Earth and Atmospheric Sciences, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, United States
AU: Ying, S
EM: shiying@cma.gov.cn
AF: National Climate Centre, National Climate Centre, Beijing, 100081, China
AU: Tung, W
EM: wwtung@purdue.edu
AF: Purdue Climate Change Research Center and Department of Earth and Atmospheric Sciences, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, United States
AU: Trapp, R J
EM: jtrapp@purdue.edu
AF: Purdue Climate Change Research Center and Department of Earth and Atmospheric Sciences, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, United States
AU: Gao, X
EM: gaoxj@cma.gov.cn
AF: National Climate Centre, National Climate Centre, Beijing, 100081, China
AU: Pal, J S
EM: jpal@lmu.edu
AF: Frank R. Seaver College of Sciences and Engineering Loyola Marymount University, 1 LMU Drive MS 8135, Los Angeles, CA 90045, United States
AU: Diffenbuagh, N S
EM: diffenbaugh@purdue.edu
AF: Purdue Climate Change Research Center and Department of Earth and Atmospheric Sciences, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, United States
AB: We present results from a high-resolution climate simulation of the south Asian monsoon using the Abdus Salam Centre for Theoretical Physics Regional Climate Model (RegCM3). The RegCM3 experiment consists of a 30-year integration from 1961 to 1990 performed at a 25 km grid spacing. Atmospheric boundary conditions for the integration are provided by the National Aeronautics and Space Administration (NASA) Finite Volume General Circulation Model (FVGCM). The ability of RegCM3 to simulate the dynamics of the summer monsoon is tested by comparing a number of fields with observations, including upper and lower level circulation patterns, seasonal mean precipitation and temperature, and variations in tropospheric temperature gradient and easterly vertical shear. Our results show that RegCM3 is able to simulate the dynamical features of the South Asian summer monsoon reasonably well. For instance, the seasonal reversal of tropospheric temperature gradient and strengthening of easterly vertical shear compare well with observations. Furthermore, summer monsoon onset dates over land match reasonably well with the long-term onset-climatology, and the interannual variations in the anomalies of the local Hadley circulation and summer monsoon precipitation are strongly correlated. The primary discrepancies occur over areas of high seasonal precipitation – such as the west coasts of India and Myanmar – where RegCM3 values exceed those found in the observations. Similarly, RegCM3 overestimates precipitation values on the lee side of the Western Ghats. Compared to the driving FVGCM simulation, the RegCM3 simulation shows significant improvement in spatial pattern of seasonal precipitation.
DE: 1620 Climate dynamics (0429, 3309)
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
DE: 3337 Global climate models (1626, 4928)
DE: 3354 Precipitation (1854)
DE: 3355 Regional modeling
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting