GROUND TRUTH MEASUREMENTS FOR THERMAL INFRARED REMOTE SENSING

Since 1971, field measurements have been made in order to establish interpretation keys for remotely sensed thermal infrared radiation in the 9.5 to 11.5 micrometer spectral range. The infrared radiation emitted by different land surfaces has been measured with a Barnes PRT5 radiometer and compared with different environmental parameters (solar radiation, net radiation, air and soil temperature at various depths, air and soil moisture, etc.). The parameters that give the closest correlation with the remotely sensed thermal radiation vary with the type of vegetable cover and with the seasons. The best correlations are obtained with soil surface temperature over bare soil and with air temperature at half the canopy height over vegetated areas. Seasonal variations of regression coefficients between soil surface temperatures and remotely sensed thermal radiation are higher on vegetated areas than on bare soil. /Author/