Background
The electrical-analog theory of mass and energy transport along concentration
gradients suggests that a quantitative estimate of the resistance to transfer
of sensible heat from the earth's surface to the atmosphere can be derived starting
from a knowledge of surface temperature and near-surface air temperature. Such
an estimate could be used to improve the land-surface characterization of weather
prediction models.
Some of our earlier work focused on the empirical relationships between radiometric
surface temperature and spectral vegetation indices (see Drought
and Fire Danger description). Taking that work as a starting point, we set
out to produce quantitative estimates of the surface resistance to sensible
heat flux over large regions of complex terrain and strongly heterogeneous vegetation
type. An essential new ingredient was a database of weather data gridded to
match the spatial resolution of the remote sensing data (see
Daymet description).