Abstrakt
Temperature inversions (TIs) have been closely studied for a variety of reasons. Here, we present an analysis of low-level TIs, based on a dataset of atmospheric soundings from the aerological station at Prague-Libuš (Czech Republic).
Measurements have been carried out here since 1974, at the four main synoptic hours. First, the homogeneity of both the radiosonde data and sounding-derived time series was investigated.
Since the homogeneity of the derived time series was affected by changes in the observation routine, only the period of 1992-2012 was further analysed. Second, diurnal and annual regimes of surface-based (SBTIs) and elevated (ETIs) temperature inversions were described.
Maximum frequency of the SBTIs occurred at 00 UTC and in September and October. During autumn, persistent SBTIs also often occurred, which could be linked to decreased cyclonicity.
Third, changes in TIs were evaluated, and the strongest trends were compared with the nearby station at Kümmersbruck (Germany). In all seasons except spring, nocturnal SBTIs decreased almost identically at both stations.
Morning SBTIs decreased as well; however, the trend was considerably stronger at Prague; and it was also mirrored by an increase in ETIs. Since only a part of these trends could be explained by changes in the large-scale circulation, other factors (low tropospheric warming, suburbanisation) are hypothesized to have affected the trends.