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Indian Journal of Radio & Space Physics (IJRSP) >
IJRSP Vol.41 [2012] >
IJRSP Vol.41(4) [August 2012] >
| Title: | Regional climate model simulations of the 2009 Indian summer monsoon |
| Authors: | Bhate, Jyoti
Unnikrishnan, C K
Rajeevan, M |
| Keywords: | Rainfall simulation
Regional climate model
Sea surface temperature |
| Issue Date: | Aug-2012 |
| Publisher: | NISCAIR-CSIR, India |
| PACS No.: | 92.60.jf; 92.40.eg |
| Abstract: | Using a regional climate model, the 2009 Indian summer monsoon
circulation and rainfall are simulated using observed sea surface temperatures
as boundary conditions. For this purpose, the Weather Research and Forecasting
(WRF) model
(V 3.2) was used as a regional climate model. The model simulations were made
for the period 1 May to 30 September with 1 May initial conditions with two
domains of 45 km and 15 km and 51 vertical
levels. The large scale monsoon circulation and rainfall patterns simulated by
the model were examined along with the diurnal and intra-seasonal variations
during the 2009 monsoon season using the TRMM 3G68 rainfall data. The results
showed a wet bias in the model rainfall simulations over the Indian region with
more rainfall in the model compared to the TRMM rainfall observations. This wet
bias was attributed to stronger low level monsoon flow in the model simulations
over the Indian region. Even though, the model simulations of atmospheric
humidity are reasonably accurate, the positive bias in the low level vorticity
contributed to the wet bias of rainfall over the Indian region. Model simulations showed errors in
characterizing the diurnal variation of monsoon rainfall over the Indian
region, especially in the observed phase angle (time of rainfall peak). The
model simulations could not capture the observed early morning rainfall peak
along the foothills of Himalayas caused by
katabatic wind flow over the hills. Model simulations of amplitude of diurnal
variation are, however, comparable with the observed amplitude derived from
TRMM satellite data. Model simulations also showed encouraging results in
simulating the intra-seasonal rainfall variations over the central Indian
region and the monsoon onset phase over the Kerala coast.
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| Page(s): | 488-500 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-105X (Online); 0367-8393 (Print) |
| Source: | IJRSP Vol.41(4) [August 2012]
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