Research Aircraft Observations of a Polar Low at the East Greenland Ice Edge

Abstract

The structure of a subsynoptic-scale cyclone (polar low) that formed along the cast Greenland ice edge during the 1989 Coordinated Eastern Arctic Research Experiment (CEAREX) is described using NOAA WP-3D research aircraft and satellite observations. Satellite imagery showed a well-defined 400-km-wide comma cloud pattern during the time of the aircraft observations. Frontal zones with marked wind shifts and thermal gradients near the surface were associated with the polar low. Although the polar low's vorticity decreased rapidly with height between 950 and 800 mb, a secondary vorticity maximum was found in the upper troposphere associated with a short-wave trough. Doppler radar and aircraft observations showed the structure of the main precipitation band to be similar to that of other polar lows observed by research aircraft. In general, the structure of the polar low resembled, except for horizontal scale, the structure of midlatitude cyclones at a similar stage of cloud field evolution.