Temperature Trends over Germany from Homogenized Radiosonde Data

Abstract

Abstract Temperature data from radiosondes over Germany have been homogenized manually. The method makes use of the different radiosonde (RS) networks existing in East and West Germany until 1990. The largest temperature adjustments, up to 2.5 K, apply to Freiberg sondes used in the east in the 1950s and 1960s. Adjustments for Graw Hamburg 1948 (H48), 1950 (H50), and Munich 1960 (M60) sondes, used in the west from the 1950s to the late 1980s, and for RKZ sondes, used in the east in the 1970s and 1980s, are also significant: 0.3–0.5 K. Small differences between Vaisala RS80 and RS92 sondes used throughout Germany since 1990 and ~2004, respectively, were not corrected for at levels from the ground to 300 hPa. Comparison of the homogenized data with other datasets—Radiosonde Innovation Composite Homogenization (RICH) and Hadley Centre Atmospheric Temperature, version 2 (HadAT2)—and with Microwave Sounding Unit satellite data shows generally good agreement. HadAT2 data exhibit a few suspicious spikes in the 1970s and 1980s and some suspicious offsets up to 1 K after 1995. Compared to RICH, the homogenized data show slightly different temperatures, by less than ~0.4 K, in the 1960s and 1970s. As reported in other studies, the troposphere over Germany has been warming by 0.2 ± 0.1 K decade−1 from ~1950 to 2013, and the stratosphere has been cooling. The stratospheric trend increases from almost no change near 230 hPa (the tropopause) to −0.4 ± 0.2 K decade−1 near 50 hPa. Trends from the homogenized data are more positive by about 0.1 K decade−1 compared to the original data, both in the troposphere and stratosphere.