85th AMS Annual Meeting

Tuesday, 11 January 2005: 11:30 AM
Intraseasonal variability of cloudiness and rainfall in the Madden-Julian Oscillation
Katherine H. Straub, Susquehanna University, Selinsgrove, PA; and D. K. Strahan and G. N. Kiladis
Previous studies of observed tropical intraseasonal variability have typically utilized remotely sensed cloud data such as outgoing longwave radiation (OLR) as a proxy for surface rainfall. The present study seeks to improve our understanding of the relationship between clouds and surface precipitation in the Madden-Julian Oscillation (MJO) through a comparison of the intraseasonal variability in four cloudiness and precipitation datasets: 1) NOAA OLR, 2) Cloud Archive User Service (CLAUS) IR brightness temperature, 3) TRMM Microwave Imager (TMI) rainfall rate, and 4) Global Daily Climatology Network (GDCN) station precipitation. Composites of each dataset are calculated for 8 phases of the MJO, based on Wheeler and Hendonís (2004) Realtime Multivariate MJO (RMM) index. Results show significant differences in the spatial distribution of peak cloudiness and precipitation as a function of MJO phase, suggesting that model validation of MJO simulations should take into account multiple observational data sources.

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