Correction of Humidity Biases in Vaisala RS80-H Sondes during NAME

Abstract

Examination of the upper-air sonde data taken in conjunction with the North American Monsoon Experiment (NAME) revealed that data at several sites in the core monsoon region exhibited a significant dry bias. In this study, a simple, yet effective, statistical correction technique is applied to correct this dry bias. In addition, a second correction is applied to all Vaisala RS80-H sondes to remove a daytime dry bias resulting from solar heating of the humidity sensor. Moisture analyses computed from the corrected sondes compare favorably to those from independent satellite and aircraft estimates. The corrections led to significant improvement in the description of the humidity field and in several convective parameters, such as precipitable water (PW), CAPE, convective inhibition (CIN), and in the diurnal cycle of apparent drying Q2.