RADARSAT-1 SAR image of a polar mesoscale cyclone from 0602 UT 05 February 1998.  RADARSAT-1 data © Canadian Space Agency.  Letters refer to features discussed in Sikora, T. D., K. S. Friedman, W. G. Pichel, and P. Clemente-Colon, 2000:  Synthetic aperture radar as a tool for investigating polar mesoscale cyclones. Wea. Forecasting., 15, 745-758.