The Cloud Clearing Task Team has set as its first priority the reduction of false flagging in regions of high sea surface temperature gradient. False flagging arises when spatial coherence tests are used: such tests are effective in discriminating clouds from sea areas in brightness temperature imagery for most of the ocean, but for frontal areas, cloud features and sea features on such metrics overlap and a compromise between failure to detect and false alarms is inevitable. However, systematic over-flagging of frontal areas is unsatisfactory for applications that explore ocean dynamics that generate fronts as a signature and quantifier of dynamical processes.
Options in development for reducing false flagging include: alternative metrics of spatial coherence, multi-temporal techniques, and (for contemporary sensors) use of additional (non-retrieval) channels.
LAST REPORT TO THE SCIENCE TEAM (GHRSST-XXI, 2020)
Task Team Members
Chair: Chris Merchant
Members: Claire Bulgin, Mike Chin, Peter Cornillon, Steinar Eastwood, Owen Embury, Andy Harris, Mingkun Liu, Boris Petrenko, Stephane Saux Picart, Yukio Kurihara