Measurement of snow and sea ice surface temperature and emissivity in the Ross Sea

The snow and sea ice surface temperature in the Ross Sea was measured aboard the NSF Research Vessel Nathaniel B. Palmer during two cruises in 1998 and 1999, including a winter cruise in May and June 1998, and a summer cruise in January and February 1999. The main objectives of the cruises were to collect sea ice surface temperature data sets using a variety of instruments, and to devise schemes for future validation of the satellite data sets to be derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). Attempts for estimation of emissivity of snow surface in the thermal infrared region were also made. The authors collected surface temperatures on 37 individual ice floes. Three sets of instruments were available, including 20 Optic StowAway thermistors, a Heintronics Model KT 19.82 infrared radiation pyrometer, and an Exergen Model DJOI-RS infrared microscanner. Each thermister has its own automatic data logger, and has been calibrated separately at the factory. The Heintronics thermal infrared pyrometer has an 8-14 /spl mu/m spectral response. The brightness temperature measurements can be read manually off the instrument screen, although a data logger with voltage output is also connected to the pyrometer for recording time series automatically and continuously. The Exergen infrared microscanner has a spectral response between 2-20 /spl mu/m. It has an automatic emissivity compensation mechanism for most real surfaces of unknown emissivity, except for metal surfaces.