MODIS LST Group
Field Measurements

We have had several successful field campaigns in Railroad Valley NV (75 miles SW of Ely), Death Valley CA, and Mammoth Lakes CA. These test areas are ideal for our research: since these silt playas (dried-up lake beds), snow fields, and inland lakes are large (> 5 km x 5 km), flat areas with uniform (or uniformly mixed) surfaces, we can reduce the uncertainty in spatial variations of the surface emissivity and temperature.

The field measurements were carried out in conjunction with airborne measurements, allowing us to test our land-surface temperature algorithms. Because the success of our algorithms relies on precise and accurate ground-truthing, it is critical that we get quality temperature and emissivity data. We measure surface temperatures in a variety of ways, including contact sensors, infrared thermometers, and infrared spectrometers. We can use the SIBRE system to measure the bidirectional reflectance distribution function (BRDF) and emissivity from spectrometer data. To determine the effects of the atmosphere, we also get water-vapor column and temperature profiles using measurements from radiosondes (radio transmitters, carried aloft by balloons, with instruments for broadcasting the humidity, temperature, pressure, etc).

We did not have direct in-situ measurement data for the spatial variation in surface temperature at the scale pertaining to the FOV (approximately 50cm) of the TIR thermometer and spectrometer up to the scale pertaining to the size (50m) of MAS pixels. We will use an IR camera to measure continuously the spatial distribution of surface temperature in future field campaigns.