Equatorial wave activity during 2007 over Gadanki

Authors: SALAUDDIN MOHAMMAD GOPA DUTTA B VENKATESWARA RAO P VINAY KUMAR

Publish Date: 2015/06/09

Volume: 124, Issue: 4, Pages: 897-908

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Abstract

ECMWF ReAnalysis ERAinterim data of winds for the year 2007 between the pressure levels 1 and 1000 hPa 0–49 km have been analyzed for equatorial wave activity over a tropical station Gadanki 135oN 792°E Available wind observations made by MST radar located at the same site have also been used to investigate the wave activity in the troposphere and lower stratosphere Waves in the period bands 7–10 12–15 and 20–30 d are observed Temporal variability of the wave activity has been investigated by constructing wavelet spectra The longer period waves show strong seasonal variability with maximum and minimum activities during winter and summer months respectively Short period activity is more prominent during June–July–August in the tropospheric region The waves are found to be generated in the troposphere by wind shear and convection Propagation of the waves to higher altitudes is found to depend strongly on background zonal wind and phase of the quasibiennial oscillation QBO The waves are inhibited to propagate through the negative wind shear zone Meridional waves might be generated by nonlinear wave CISKAuthors wish to express their gratitude to the Director National Atmospheric Research Laboratory NARL Gadanki for providing data for the analysis Two of the authors Salauddin Mohammad and P Vinay Kumar are thankful for the research fellowships offered by Indian Space Research Organization ISRO under its CAWSES programme The authors would also like to thank the college management for their kind support The authors thank the anonymous reviewer for his constructive comments which substantially improved the quality of the paper

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