A gridded reconstruction of land and ocean precipitation for the extended tropics from 1974 to 1994

Abstract

This paper describes a new 3.75° longitude by 2.5° latitude gridded monthly precipitation data series for the extended tropical region from 30°N to 30°S and covering the period 1974–1994. This new dataset combines the pre-existing land-based 3.75°×2.5° resolution gridded monthly precipitation series of Hulme for the period 1974–1994, with a new monthly oceanic precipitation climatology, constructed from satellite outgoing longwave radiation (OLR) measurements also for the period 1974–1994. This latter dataset, which has been calibrated against available atoll raingauge observations, provides the longest record of satellite-derived precipitation estimates. A mean reliability index field to accompany this OLR-derived climatology is created from comparisons performed with two other satellite-derived precipitation datasets: the microwave sounding unit (MSU) precipitation dataset of Spencer and the preliminary global precipitation climatology project (GPCP) dataset developed at the Global Precipitation Climatology Centre. A Poisson blending technique is used to merge the land- and OLR-derived oceanic precipitation datasets to produce an extended tropical region climatology, suitable for global climate model validation and for other climatological analyses. This blended dataset shows good agreement with the GPCP product over the tropical region for the years 1986–1993. Copyright © 1999 Royal Meteorological Society