The Hillarys Transect sea surface temperature measurement and validation program

Abstract

There has been a heightened interest in sea surface temperature (SST) measurements during the past two decades, particularly on a global scale, due largely to the advent of several El Nino episodes and increasing worldwide concern about global warming. Because of the continuous global measurements of SST that satellites can provide they play a fundamental role in acquiring the data sets necessary for studies of such global processes. However, the satellite data still need to be validated against in-situ measurements in order to assess the accuracy of satellite SST retrieval algorithms. Since 1997 radiometric sea surface skin temperatures have been recorded monthly using a TASCO radiometer along a cross shelf transect extending 40 km offshore from a coastal location north of Perth, Western Australia. This SST measurement program is one component of the Hillarys Transect, an ongoing multidisciplinary oceanographic study which aims to quantify the seasonal variation of physical and biological variables in the coastal Indian Ocean. Validation of satellite SST retrieval algorithms is the primary aim of the SST measurement program component of the Hillarys Transect, which also aims to develop a data set which captures the seasonal variation of SST off the coast of southern Western Australia (WA). The radiometric SST measurements are made at 9 stations along the transect and each measurement is calibrated using a portable water-filled blackbody unit. Though the study is low budget, the seasonal variation in SST is clearly captured by the data set and good agreement between in-situ and satellite SST estimates are obtained. Calibration of the radiometer is discussed along with the seasonal cycle of SST off the WA coast and the suitability of the instrumentation for validation of remotely sensed SST.