Radiometric observations of vines from the green period to the withering

The SMOS REFLEX 2006 field experiment aimed to monitor changes in the L-band (1.4 GHz) emission of vineyards as a function of the plants development. The experiment site was the Valencia Anchor Station, which has been selected as a calibration/validation site for the ESApsilas Soil Moisture and Ocean Salinity (SMOS) mission. This paper presents SMOS REFLEX 2006 and shows the temporal variation of the emissivity. The daily emission decreases from dusk till dawn and then increases again in the daylight hours. This oscillation in the emissivity has a peak to peak variation up to 0.05 (~ 15 K in brightness temperature). Emissivity decreases with time, especially at H-polarisation, due to the increase in the vegetation water content before harvest, and to the increase in soil moisture due to rain events after harvest. The contribution of soil to the measured emissivity is larger after harvest and at incidence angles smaller than 55deg . In this case, an increase in the rock-fraction decreases the mean range of emissivity up to 68%.