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Interannual Variation of Monsoon in a High Resolution AGCM with Climatological SST Forcing

Electronic Theses of Indian Institute of Science

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Title Interannual Variation of Monsoon in a High Resolution AGCM with Climatological SST Forcing
 
Creator Ghosh, Rohit
 
Subject Monsoon - Interannual Variation
Climatological Sea Surface Temperature
Monsoon Rainfall - Summer - India
Monsoon Precipitation - India
Pre-Monsoon Soil Moisture
Monsoon Variability
Summer Monsoon - India - Interannual Variation
Monsoon Circulation Model
Indian Summer Monsoon Rainfall (ISMR) - Interannual Variation
Intraseasonal Oscillation
Atmsopheric and Oceanic Sciences
 
Description Interannual variation of Indian summer (June-September: JJAS) monsoon rainfall (ISMR) depends on its relative intensity during early (June-July: JJ; contribution 52%) and late (August-September: AS; contribution 49%) phases. Apart from variations in sea surface temperature (SST), the primary reasons behind the variability during JJ and AS can be very different due to change in climatic conditions on account of post-onset processes. Here, using a high resolution general circulation model with seasonally varying climatological SST, mechanisms those govern the intensity of rainfall during JJ and AS are investigated. There is no significant relation-ship between intensity of precipitation over Indian region in JJ and AS. Moreover, the factors determining early monsoon (JJ) precipitation are different than that for late monsoon (AS). In absence of interannual SST variation, pre-monsoon soil moisture do not play a significant role for the interannual variation of monsoon precipitation over India. A large scale oscillation of the ITCZ is noticed on interannual time scale spanning from around 60◦E to 150◦E that brings spatially coherent flood and drought over this region. Early monsoon precipitation has a larger dependency on spring snow depth over Eurasia and phase of the upper tropospheric Rossby wave in May. However, late monsoon precipitation over India is mainly governed by the intensity and time scale of the intraseasonally varying convective cloud bands. This study suggests that early monsoon (JJ) precipitation over Indian region is more correlated with pre-monsoon signatures of land-atmosphere parameters. However, in later parts after the onset (AS), the monsoon intensity is primarily driven by its internal dynamics and characteristics of intraseasonal oscillation.
 
Contributor Chakraborty, Arindam
 
Date 2018-04-06T04:38:37Z
2018-04-06T04:38:37Z
2018-04-06
2013
 
Type Thesis
 
Identifier http://etd.iisc.ernet.in/2005/3350
http://etd.iisc.ernet.in/abstracts/4216/G25744-Abs.pdf
 
Language en_US
 
Relation G25744