Following the field phase of TOGA COARE it became evident that the sounding systems in the COARE domain exhibited a variety of humidity errors. The Vaisala sensors, used at several key sites, generally reported humidity errors about 5% too dry in the boundary layer. In contrast, the soundings systems around 10 N and at several sites in Indonesia used a VIZ hygristor sensor which displayed a moist bias. In the NCEP and ECMWF reanalyses of the COARE period, persistant excessive rain between 5 and 10 N and a dry bias near the equator appear related to the moisture biases in the sonde data.

Because of the importance of the COARE sounding data set to describe and understand the coupled ocean-atmospheric system in western Pacific warm pool, a humidity correction procedure was developed by the Atmospheric Technology Division of the National Center of Atmospheric Research (NCAR/ATD) and then applied to correct over over 14,000 soundings. To assist us in evaluating the humidity corrections, an objectively analyzed, high resolution gridded data set will be produced over the Large Scale sounding Array (LSA) of COARE using the corrected sondes. With this gridded data product we will examine the magnitude of the humidity correction and its impacts on various atmospheric analyses (e.g., moisture budgets, rainfall, CIN and CAPE).