Inhaltszusammenfassung

The baroclinic development of an intense meso-scale cyclone (MC) over the Weddell Sea near the Antarctic coast close to the German Georg-von-Neumayer Station (GvN) during the period 26-28 April 1989 was studied by means of satellite and conventional data. ECMWF analyses, radiosonde data and surface observations were used tagether with A VHRR data, TOVS and SSM/I retrievals for the description of the synoptic and subsynoptic environment associated with the development of the MC. The MC...The baroclinic development of an intense meso-scale cyclone (MC) over the Weddell Sea near the Antarctic coast close to the German Georg-von-Neumayer Station (GvN) during the period 26-28 April 1989 was studied by means of satellite and conventional data. ECMWF analyses, radiosonde data and surface observations were used tagether with A VHRR data, TOVS and SSM/I retrievals for the description of the synoptic and subsynoptic environment associated with the development of the MC. The MC bad a diameter of about 500 km, a lifetime of about 40 hours and reached the intensity of a polar low. Wind speeds up to 19 m/s (with gusts up to 24m/s) were recorded at GvN as the MC approached on 27 April and remained quasi-stationary for about 24 hours. Its development took place in baroclinic conditions of strong low-level cold air advection close to the sea ice front. The genesis of the MC seemed to be triggered by a 500hPa short"wave trough and a resemblance to a baroclinic devel­ opment at a boundary layer front was noticed. Low-level thickness fields from TOVS data reflected the baroclinic structure of the MC, but gradients were relatively weak. Wind speed retrievals from SSM/I data did not allow a full analysis of the wind field structure for this case, as they were limited to ice-free ocean. They showed the incipient MC lying in an area with increased wind speed and high surface fluxes of sensible heat. In the mature stage, a maximum in the SSM/1 wind speed field was found in the northwestern part of the MC. A meso-scale analysis with a limited area assimilation system for the mature stage showed only weak support ofthe low-level MC by upper Ievel cyclonic vorticity advection.» weiterlesen» einklappen

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DDC Sachgruppe:
Naturwissenschaften