Rainfall Variability over the Tropical Pacific from July 1987 Through December 1991 as Inferred via Monthly Estimates from SSM/I

Wesley Berg

Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder

Susan K. Avery

Department of Electrical and Computer Engineering, University of Colorado, Boulder

ABSTRACT

Estimates of monthly rainfall have been computed over the tropical Pacific using passive microwave satellite observations from the Special Sensor Microwave/Imager (SSM/I) for the period from July 1987 through December 1991. The monthly estimates were calibrated using measurements from a network of Pacific atoll rain gauges and compared to other satellite-based rainfall estimation techniques. Based on these monthly estimates, an analysis of the variability of large-scale features over intraseasonal to interannual time scales has been performed. While the major precipitation features as well as the seasonal variability of the rainfall distributions show good agreement with expected values, the presence of a moderately intense El Nino during 1986-87 and an intense La Nina during 1988-89 highlights this time period.