Operational Ocean Search and Rescue Using AVHRR: Cloud Limitations

Sea surface currents can be derived from sequential Advanced Very High Resolution Radiometer (AVHRR) images. However, the operational feasibility of deriving ocean surface currents from AVHRR is severely limited by the inability of AVHRR to penetrate cloud cover. The application of AVHRR-derived currents is therefore limited to times and areas that are relatively cloud free. Three experiments were performed to evaluate the operational feasibility of AVHRR-derived sea surface currents: one offshore near Cape Race, St. John’s, Newfoundland, Canada, and two in the Delaware Coastal Current (DCC). Almost all of the Cape Race images, 60% of the 1993, and 40% of the 1994 DCC Experiment images had clouds covering the entire image. An additional 25%‐30% of the images had clouds covering part of the region, further reducing the number of images suitable for velocity estimation. Possibilities for overcoming this limitation are discussed.