TEMPORAL INHOMOGENEITIES IN RADIOSONDE TEMPERATURE RECORDS

Historical information on changes in radiosonde instruments and observ ing methods is combined with time series of upper-air temperature data to estimate the effects of (1) changes in sensors, (2) changes in sol ar radiation corrections to the data, and (3) changes in the length of the train between the balloon and the instrument package. These chang es can induce discontinuities in the temperature records from several tenths to as high as several degrees Celsius. The discontinuities can be larger than the temperature trends of a few tenths of a degree per decade, computed by previous investigators from radiosonde observation s An assessment of the 63-station network used by Angell to monitor tr opospheric and stratospheric temperature suggests that about 43% of th ose stations' records have inhomogeneities, most notably in the strato sphere. These findings suggest that some previously computed temperatu re trends, especially estimates of stratospheric cooling, may be influ enced by data inhomogeneities.