Factors Contributing to the Spatial Variability of Satellite Estimates of Diurnal Temperature Range in the United States

Diurnal temperature range (DTR) is an important index of climate change that can be affected by many environmental factors. The impact of each of these factors on DTR is still much debated. We show that the cooling effect due to transpiration from dense vegetation on land surface temperature (LST) is more evident during daytime than nighttime, which makes the difference between daily maximum and minimum LSTs
$(\hbox{LST}_{\max} - \hbox{LST}_{\min})$
or DTR decrease with vegetation; this is seen only during the growing season. DTR drops with soil moisture (SM) for all seasons. The effect of water vapor (WV) radiative forcing makes DTRs decrease during the warm seasons (summer and fall) and may have affected most significantly the dip of DTR during summer over the southern two-thirds of the eastern United States. During summer, the effects of vegetation and WV on the decrease in DTR are more significant than other factors such as SM and aerosols.