SHEBA is a year-long experiment to study the Surface Heat Budget of the Arctic Ocean. Because correctly measuring the snow or ice surface temperature is crucial to determining and parameterizing the surface heat budget, we have given the surface temperature a lot of attention. In this paper, we will discuss the different methods and instruments that we are using to measure surface temperature during SHEBA and will compare data obtained with the various instruments.
Our methods of measuring surface temperature range from radiative, to in situ, to a novel hygrometric method. The radiative instruments include a Barnes precision radiation thermometer and sets of upward and downward-looking Eppley pyrgeometers. The in situ sensors are a vertical array of closely spaced thermistors that extend from the sea ice, through the snow, and into the near-surface air. Lastly, we use a cooled-mirror dew-point hygrometer placed within a few centimeters of the surface to measure the dew point. If the near-surface air is saturated, the measured dew point will, essentially, be the surface temperature.
All of these instruments were within 300 meters of each other for the duration of SHEBA. By the end of the experiment in October 1998, we will have a full year of surface temperature data from all these instruments on a single ice floe. We will focus our analysis in this presentation on short sections of the data from each season to see whether the various measurement techniques have any seasonal biases. For example, November 1997 is designated a preliminary SHEBA-wide intercomparison period; thus, data quality for this period is crucial. January 1998 features total darkness and, thus, the assurance that none of the sensors suffer from solar heating. March is a transition month, when sunlight is again becoming a factor. Finally, June and July provide lots of sunlight, which may confound the in situ sensors, and a predominance of warm clouds, which likely influence temperatures computed from the pyrgeometers