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Clustering of synoptic activity by Indian summer monsoon intraseasonal oscillations
Author(s) -
Goswami B. N.,
Ajayamohan R. S.,
Xavier Prince K.,
Sengupta D.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2002gl016734
Subject(s) - climatology , monsoon , trough (economics) , monsoon trough , precipitation , geology , zonal and meridional , atmospheric sciences , monsoon of south asia , east asian monsoon , meteorology , geography , economics , macroeconomics
Active and break phases of the Indian summer monsoon are characterized by enhancement and decrease of precipitation over the monsoon trough region. Using genesis data of monsoon low pressure systems (LPS) and circulation data for the period 1954 to 1993, it is shown that the frequency of occurrence of LPS is nearly 3.5 times higher in the active phase of monsoon as compared to the break phase. In addition, the tracks of these synoptic systems are also strongly spatially clustered along the monsoon trough during the active phase of the monsoon. The enhanced (decreased) frequency of occurrence of LPS during active (break) phases is due to modulation of meridional shear of zonal winds and cyclonic vorticity along the monsoon trough by the intraseasonal oscillations (ISO).