Atmospheric vortex streets on a RADARSAT SAR image

We analyze the sea surface imprint of two atmospheric vortex streets (AVS's ) observed on a RADARSAT, a Canadian earth observation satellite, Synthetic Aperture Radar (SAR) image of the Aleutian Islands in the western Gulf of Alaska acquired on May 5, 1999. The RADARSAT SAR instrument is operated in C-band with HH polarization. These AVS's are interpreted as the atmosphere analog of classic Von Karman vortex streets. The SAR image, along with radi osonde data and surface weather charts, reveal that the AVS lengths are 196 km and 111 km for AVS-1 and AVS-2 respectively. There are five and two pai rs of Vortices within each AVS. The vortex shedding period is estimated to be between 35 and 48 minutes. The vortex shedding started approximately 4.6 and 2.6 hours prior to the SAR imaging time for AVS-1 and AVS-2, respectiv ely. There are seven and three pairs of vortices within the respective AVS' s. The vortex tangential velocity is estimated to be between 1.7 and 2.3 m/ s and the energy dissipated during the vortex lifetime is estimated to be b etween 24.9 and 23.6 J/m(3).