The Diurnal Cycle of Convective Activity over South Asia as Diagnosed from METEOSAT-5 and TRMM Data

  • Author(s): Bhuwan Chandra Bhatt, Tieh-Yong Koh, Munehisa Yamamoto, and Kenji Nakamura
  • DOI: 10.3319/TAO.2010.02.04.01(A)
  • Keywords: Convective activity Diurnal variation Climatology South Asia
  • Citation: Bhatt, B. C., T. Y. Koh, M. Yamamoto, and K. Nakamura, 2010: The diurnal cycle of convective activity over South Asia as diagnosed from METEOSAT-5 and TRMM data. Terr. Atmos. Ocean. Sci., 21, 841-854, doi: 10.3319/TAO.2010.02.04.01(A)

Cloud and precipitation data from satellites were used to characterize the climatological diurnal cycle of convective activity over South Asia. Spatial and temporal variability were investigated using three hourly blackbody brightness temperature (TBB) data from the METEOSAT-5 during March-April-May (pre-monsoon) and June-July-August (summer monsoon) of 1999 - 2000. We focused on three regions over South Asia: region A in the Himalayas, region B in north India and region C in the Bay of Bengal (BOB). The cloud cluster (CC) technique was used first to detect deep convection over north India during the summer monsoon when deep convection was less frequent; cloud cover frequency (CCF) was used to diagnose convection of a moderate depth. TBB thresholds of 219 and 235 K were used in the CC and CCF methods, respectively. Ten years of Tropical Rainfall Measuring Mission (TRMM) rainfall product (3B42) was analyzed as well to check the METEOSAT-5 findings.

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