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Comparison of definitions of Indian summer monsoon onset: Better representation of rapid transitions of atmospheric conditions
Author(s) -
Taniguchi Kenji,
Koike Toshio
Publication year - 2006
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 - 10.1029/2005gl024526
Subject(s) - monsoon , climatology , environmental science , representativeness heuristic , wind speed , wet season , atmospheric sciences , atmospheric dynamics , meteorology , geography , geology , mathematics , atmosphere (unit) , statistics , cartography
Onset of the Indian Summer Monsoon (ISM) has been defined by various methods, but it is uncertain which definition is most adequate. Focusing on the rapid transition of atmospheric conditions and correspondence with rainfall from 1997 to 2004, we compare the representativeness of ISM onset described by three variables spatially averaged over the Arabian Sea. Though integrated water vapor significantly increases, it cannot detect the beginning of the rainy season. Moisture transport shows rapid increase, and represents the abrupt transition of atmospheric conditions. However, it sometimes fails to determine the start of monsoon rainfall. Rapid enhancement of the low‐level wind speed shows good agreement with the abrupt beginning of the rainy season, and it represents the clear transition in atmospheric fields. The onset criterion based on the wind speed is easier, clearer, and successfully screens out “Bogus onset”, and is therefore more suitable to define the ISM onset.