THE USE OF CLIMATOLOGICAL OBSERVATIONS AS GROUND TRUTH FOR DISTRIBUTIONS OF MINIMUM TEMPERATURE DERIVED FROM AVHRR DATA

Minimum temperature is an important climatological element, but the distribution of climatological stations may not be suitable for more than a coarse resolution of the spatial variation in minimum temperature. Land surface temperatures can be derived from AVHRR data but there are a number of problems, particularly variations in emissivity and the use of appropriate ground truth. The emissivity variations can be minimized by selecting dates with a widespread deep snow cover. The appropriate ground truth for the AVHRR data might be expected to be the surface minima but this study suggests that they are subject to very local influences and that screen minima are more reliable. The results may have a general application to snow-covered higher latitude areas of similar relief.