Observing Cold-Night Temperatures of Agricultural Landscapes with an Airplane-Mounted Radiation Thermometer

Abstract

Surface temperatures of agricultural landscapes were measured during three nights of impending freeze with an airplane-mounted precision radiation thermometer (PRT) to determine the suitability of the instrument for this purpose and to examine the recorded temperature patterns. Temperature transects were obtained that represented strips of land 5.2 to 10.4 m wide and up to several kilometers long. Agricultural fields varying in surface conditions and engineering features (such as drainage ditches, roads, and irrigation canals) were distinguishable by their thermal and spatial characteristics on stripchart recorder traces. The equivalent blackbody temperatures of shelterbelts and the areas in their immediate vicinity were as much as 3°C warmer than the intervening space between shelterbelts. The effect of soil moisture conditions on nocturnal surface temperatures was apparent in PRT data collected about 25 h after rainfall.