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Ramkumar, Geetha
- Planetary Waves - Major Forcing Agent in Generating Stratospheric and Mesospheric Quasi Biennial Oscillation
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PDF Views:91
Authors
Affiliations
1 Space Physics Laboratory, Vikram Sarabhai Space Centre, ISRO-Department of Space, Thiruvananthapuram 695 022, IN
1 Space Physics Laboratory, Vikram Sarabhai Space Centre, ISRO-Department of Space, Thiruvananthapuram 695 022, IN
Source
Current Science, Vol 106, No 9 (2014), Pagination: 1260-1269Abstract
Quasi Biennial Oscillation (QBO) and Semi Annual Oscillation (SAO) are dominant natural oscillations in the equatorial lower stratosphere and mesosphere and are believed to be generated by the wave-mean flow interaction. The characteristics of stratospheric QBO (SQBO) and mesospheric QBO (MQBO) and SAO are studied by making use of the monthly mean zonal and meridional winds derived from four decades of balloon (1970-2010) and rocket (1971-2007) flights and seven years of SKiYMET meteor radar (2004-2011) observations over an equatorial station Thiruvananthapuram. The year-to-year variation and interrelationships between these oscillations are also studied. The quantitative estimation of forcing towards the mean flow acceleration producing the maximum phase of SQBO during the four-decade period shows 70-80% contribution from planetary waves, while during minimum phase of SQBO the contribution is 30-35%. It is also found that the contribution by planetary waves towards the mean flow acceleration producing MQBO maximum during the seven-year period is around 30-90% and during MQBO minimum phase it is 30-60%. The vertical structure of these oscillations present over the equatorial station is also derived.Keywords
Quasi Biennial Oscillation, Mean Flow Acceleration, Mesosphere, Planetary Waves, Stratosphere.Full Text
- Climatology of Horizontal Winds in the Lower and Middle Atmosphere over an Equatorial Station - Thiruvananthapuram
Abstract Views :250 |
PDF Views:78
Authors
Affiliations
1 Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695 022, IN
2 All Saints’ College, Thiruvananthapuram 695 008, IN
1 Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695 022, IN
2 All Saints’ College, Thiruvananthapuram 695 008, IN
Source
Current Science, Vol 111, No 3 (2016), Pagination: 500-508Abstract
The climatology of prevailing horizontal winds in the 0-98 km region over an equatorial station Thiruvananthapuram is presented here. The climatology of horizontal winds is derived by making use of monthly mean zonal and meridional winds obtained from four decades of balloon flights (1970-2010), three decades of rocket flights (1971-1993, 2002-2007) and one decade of SKiYMET meteor wind radar (2004-2014) observations. The observed climatology is compared with the global scale wave model (GSWM-09), and similarities and differences are discussed. Seasonal trends in the horizontal winds and features specific to the equatorial region are also discussed.Keywords
Climatology, Equatorial Station, Horizontal Winds, Middle Atmosphere.Full Text