Use of Radiosonde Temperature Data in Climate Studies

Abstract

Ten of the most common radiosondes used throughout the world since 1960 have been evaluated concerning potential use of their temperature data for climate studies. The VIZ; Space Data Corp.; Chinese GZZ; Japanese RS2-80; Russian RKZ, MARS, and A-22; and Vaisala RS80, RS 12/15, and RS18/21 radiosondes were evaluated by modeling the temperature of the sensing element relative to the temperature of the air in which it is immersed. The difference, designated as the temperature error, was calculated under various environmental conditions. Validation and sensitivity analysis studies were performed on each radiosonde model as a means of estimating the environmental parameters that influence the temperature error and the resulting accuracy of the day and nighttime temperature profiles. Environmental parameters to which some sondes were sensitive include cloud cover, surface temperature, solar angle, ambient temperature profile, blackbody temperature, and the ventilation velocity. The ventilation velocity was found to depend strongly on the position of the sensor in the balloon wake. It is believed that the results of these analyses provide the best guidelines available to anyone wishing to perform climate studies using radiosonde data. The research work presented in this paper indicates that climate trends can currently be estimated with a subset of the worldwide upper-air data. Trends can be calculated for monthly averaged, nighttime soundings with some confidence for the Vaisala RS80 (models not using the RSN80 and RSN86 corrections), Vaisala RS 12/15, Vaisala RS 18/21, Chinese GZZ (below 25 km), Russian RKZ, Russian MARS, and Russian A-22 (below 20 km) radiosonde models. The analysis presented in this paper shows that all of the above radiosondes have small errors in individual radiosonde soundings at night (< ±1°C) and the errors of the monthly averaged data are estimated to be less than ±0.5°C, except for the A-22 (±0.8°C). In addition, temperature data from the Japanese RS-2-80, the Russian A-22 above 20 km, Vaisala RS80 (RSN80 and RSN86 corrections applied), and VIZ can be made suitable for climate analysis if the appropriate temperature correction models are used to correct the data.