Variable seasonal coupling between air and ground temperatures: A simple representation in terms of subsurface thermal diffusivity

Pollack, Henry N.; Smerdon, Jason E.; Keken, Peter E. van

The utility of subsurface temperatures as indicators of temperature changes at Earth's surface rests upon an assumption of strong coupling between surface air temperature (SAT) and ground surface temperature (GST). Here we describe a simple representation of this coupling in terms of a variable thermal diffusivity in the upper meter of the subsurface. The variability is tied to daily SAT, precipitation, and snow cover, but does not incorporate the physical details of these and the many other factors that influence the air-ground interface in many high-fidelity land-surface models. Our simple model reduces the difference between observed and modeled temperatures by a factor of 3 to 4 over a model with uniform diffusivity driven only by SAT. This simple representation of air-ground coupling offers a means of simulating subsurface temperatures using only archived meteorological records and creates the potential for examining the long term character of air-ground temperature coupling.


Also Published In

Geophysical Research Letters

More About This Work

Academic Units
Lamont-Doherty Earth Observatory
Ocean and Climate Physics
American Geophysical Union
Published Here
August 24, 2011