Humidity inversions have a high potential importance in the Arctic climatesystem, especially for cloud formation and maintenance, in wide spatial andtemporal scales. Here we investigate the climatology and characteristics ofhumidity inversions in the Arctic, including their spatial and temporalvariability, sensitivity to the methodology applied and differences from theAntarctic humidity inversions. The study is based on data of the IntegratedGlobal Radiosonde Archive (IGRA) from 36 Arctic stations between the years2000 and 2009. The results indicate that humidity inversions are present onmultiple levels nearly all the time in the Arctic atmosphere. Almost half(48%) of the humidity inversions were found at least partly within thesame vertical layer with temperature inversions, whereas the existence ofthe other half may, at least partly, be linked to uneven verticaldistribution of horizontal moisture transport. A high atmospheric surfacepressure was found to increase the humidity inversion occurrence, whereasrelationships between humidity inversion properties and cloud cover weregenerally relatively weak, although for some inversion properties they weresystematic. For example, humidity inversions occurred slightly more oftenand were deeper under clear sky than in overcast conditions for almostall stations. The statistics of Arctic humidity inversion properties,especially inversion strength, depth and base height, proved to be verysensitive to the instruments and methodology applied. For example, themedian strength of the strongest inversion in a profile was twice as largeas the median of all Arctic inversions. The most striking difference betweenthe Arctic and Antarctic humidity inversions was the much larger range ofthe seasonal cycle of inversion properties in the Arctic. Our results offera baseline for validation of weather prediction and climate models and alsoencourage further studies on humidity inversions due to the vital, but sofar poorly understood, role of humidity inversions in Arctic cloudprocesses.
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