Long term variability in temperature in the upper troposphere and lower stratosphere over Indian and Indonesian region using Atmospheric Infrared Sounder (AIRS) observations

Abstract

The spatio-temporal patterns and vertical structure of the temperature anomalies, obtained from Atmospheric Infrared Sounder (AIRS), spanning over 9 years (2003-2011) over Indian and Indonesian regions in the upper troposphere and lower stratosphere (UTLS) region, have been examined. An equatorial biennial oscillation with amplitude ranging ~4-6 K and having a period of ~24 months was observed in lower stratosphere (LS) from 100 to 50 hPa, whereas it was not seen in the upper troposphere (UT) from 150 to 200 hPa over both the Indian and Indonesian regions. At 50, 70 and 100 hPa, the<span style="mso-bidi-font-size: 12.0pt" lang="EN-US"> annual oscillations (AO) with amplitude ~1-3.5 K were observed near equator in the UT region (at 150 and 200 hPa). However, near subtropics, the nature and amplitude of AO over Indian and Indonesian region was found to be different at different pressure levels. The amplitude of AO at 50 and 70 hPa was larger by ~1.0-1.5 K over Indonesian region as compared to Indian region. But at 100 and 200 hPa, the amplitude of AO over Indian region was larger by ~2-3 K, as observed over Indonesian region. It was also observed that the subtropical AO over both the regions was found to be out of phase with the equatorial AO. The subtropical warm temperature anomalies at 100 hPa were found to be typically collocated with subtropical higher values of ozone (using AIRS data) present in the LS. It was also noted that the temperature anomalies at 100 hPa were also found to be anti-correlated with those at 200 hPa.

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