Passive Microwave Measurements of Temperature And Salinity in Coastal Zones

Abstract

A technique to remotely measure sea-surface temperature and salinity was demonstrated with a dual-frequency microwave radiometer system developed at the NASA Langley Research Center. Acuracies in temperature of 1°C and 1 part per thousand in salinity were obtained using state-of-the-art radiometers. Several aircraft programs for the measurement of coastal area waters demonstrating the application of the microwave radiometer system are discussed. Measurements of coastal zone ocean temperature and salinity are useful for studying the circulation in bay areas and tracing river outflow. Flight measurements in 1976 from an aircraft at an altitude of 1.4 km over the lower Chesapeake Bay and coastal areas of the Atlantic Ocean resulted in contour maps of sea-surface temperature and salinity with a spatial resolution of 0.5 km. Recent measurements (1980) at an altitude of 170 m were obtained over the Chesapeake Bay mouth and southward along the Virginia coast to study the Chesapeake Bay Plume. Because the surface area above submarine springs of fresh water exhibit temperatures and salinities lower than the surrounding sea waters, the multifrequency radiometer system was used in 1978 to detect submarine fresh water springs of the coastal areas around the island of Puerto Rico. Forty-four submarine fresh water springs were identified. In 1979, a quasi-synoptic survey of tidally induced salinity changes off the Georgia coast was performed using the microwave radiometers onboard a NASA aircraft.