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Energetics of lower tropospheric ultra-long waves: A key to intra-seasonal variability of Indian monsoon

Authors
  • Bawiskar, S. M.1
  • Chipade, M. D.1
  • Puranik, P. V.1
  • 1 Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pune, 411 008, India , Pune (India)
Type
Published Article
Journal
Journal of Earth System Science
Publisher
Springer-Verlag
Publication Date
Apr 01, 2009
Volume
118
Issue
2
Pages
115–121
Identifiers
DOI: 10.1007/s12040-009-0019-4
Source
Springer Nature
Keywords
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Abstract

Analysis of fifty four (1951–2004) years of daily energetics of zonal waves derived from NCEP/NCAR wind (u and υ) data and daily rainfall received over the Indian landmass (real time data) during southwest monsoon season (1 June–30 September) indicate that energetics (momentum transport and kinetic energy) of lower tropospheric ultra-long waves (waves 1 and 2) of low latitudes hold a key to intra-seasonal variability of monsoon rainfall over India. Correlation coefficient between climatology of daily (122 days) energetics of ultra-long waves and climatology of daily rainfall over Indian landmass is 0.9. The relation is not only significant but also has a predictive potential. The normalised plot of both the series clearly indicates that the response period of rainfall to the energetics is of 5–10 days during the onset phase and 4–7 days during the withdrawal phase of monsoon over India. During the established phase of monsoon, both the series move hand-in-hand. Normalised plot of energetics of ultra-long waves and rainfall for individual year do not show marked deviation with respect to climatology. These results are first of its kind and are useful for the short range forecast of rainfall over India.

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