Bremen 2017 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 6: Methoden - Fernerkundung

UP 6.2: Vortrag

Mittwoch, 15. März 2017, 09:00–09:15, GW2 B3009

Automatic detection of polar mesocyclones using satellite microwave humidity sounders — •Christian Melsheimer — nstitute of Environmental Physics, University of Bremen, Germany

Polar mesocyclones are small intense cyclones in polar and subpolar areas. They are challenging to observe, model and predict because of their small size, rapid development and short lifetime. Therefore polar mesocyclones and polar lows (PLs i.e., particularly strong PMCs over the sea) are poorly monitored – yet they have significant influence on atmosphere, ocean and sea ice. Here we present first results of an automatic detection algorithm, based on a simple threshold-based method using data from microwave humidity sounders (AMSU-B and MHS) on several operational meteorological satellites: On maps of the difference between the channels at 183±1 GHz and 183±7 GHz, PMCs over open ocean are visible as small patches of reversed sign. Such PMC signatures can be found by a classification algorithm that determines the size and shape of the patches and joins clusters of them if they are close enough to be considered belonging to the same cyclone. Such an algorithm must be trained, i.e., the distinguishing features of a PMC signature (size, shape, distance to similar signatures) have to be determined. This algorithm training is done by analysing signatures of about 100 known PMCs and PLs cases over the Norwegian Sea between 2000 and 2010. An automatic PMC and PL detection algorithm will allow to compile inventories of PMCs during the whole period of AMSU-B/MHS data (1999 to date). Until now, all such inventories had to be compiled by manual interpretation of satellite data.