Increases in the concentrations of atmospheric gases that absorb thermal radiation ("greenhouse gases") imply as a climate system response, a rearrangement of temperature fields to compensate for the increased atmospheric opacity. The conventional measurement used in climate change study has been surface air temperature obtained from the WMO stations, which represents some combination of the surface radiative temperatures and that of the overlying atmosphere. Measurements of surface radiative temperature from space, i.e. skin temperature, could be more directly interpretable in terms of the surface response to increase of greenhouse gases.

NOAA-series polar-orbiting satellites have monitored skin temperature using AVHRR for more than twenty years. Based on this twice-per-day measurement, we infer diurnal cycle of skin temperature (LSTD) over land for 1981-1998. LSTD shows an increase trend for land skin temperature in the past two decades. Comparisons with NCEP reanalysis and in situ observations demonstrate that this increase trend is consistent with the model simulations and surface observations, but at a larger rate than that of surface air temperature. Furthermore, skin temperature change varies significantly across the globe, and this is partly related to land vegetation cover and its changes during the same time.