Boundary-Layer Meteorology

Three types of thermocouple sensing elements were used to measure potato leaf temperatures in the uppermost layer of the canopy. A comparison between thermocouple hypodermic needles inserted into the midrib of the potato leaf and thermocouple clips fastened on its surface gave near-identical temperature readings. Miniature screens housing thermocouple sensors exposed at the upper canopy level and measuring ambient air temperatures showed excellent agreement (r = 0.996, N = 68) with potato leaf temperatures. This was not the case for temperatures recorded at the standard meteorological screen 2 m above the ground. It is therefore suggested that for micrometeorological measurements, where accuracy of crop temperature values is biologically significant, accurate information can be obtained with such miniature screens.