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Pre‐monsoon to monsoon change in direction of vertical motions in the tropical lower troposphere from UHF radar observations
Author(s) -
Ernest Raj P.,
Deshpande Sachin M.
Publication year - 2008
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 - 10.1029/2008gl034421
Subject(s) - monsoon , troposphere , climatology , wind profiler , geology , zonal and meridional , atmospheric sciences , subsidence , environmental science , radar , telecommunications , paleontology , structural basin , computer science
Multi‐height vertical wind data in the lower troposphere (1.05 – 3.75 km) obtained from Wind Profiler/UHF radar at Pune (18°32′N, 73°51′E), India during June 2003 – May 2006 has been used here to investigate the seasonal evolution in the vertical structure, especially the change taking place from pre‐monsoon (March – May) to south west monsoon (June – September) season. Vertical motions are predominantly upward during winter (December – February) and are strongly downward during pre‐monsoon. A transition from downward to upward motion takes place around early June coinciding with the local onset of SW monsoon. Kinetic energy computed from zonal and meridional winds is small in magnitude during pre‐monsoon but shows an abrupt and explosive increase around the time onset of monsoon. The results thus provide an observational evidence of existence of strong subsidence in the lower troposphere during pre‐monsoon which weakens and vertical winds turn upward signaling the arrival of monsoon conditions.