A Two-Column Model Parameterization for Subgrid Surface Heterogeneity
Driven Circulations
Abstract
Earth system models currently struggle to account for the complex
effects that land surface heterogeneity can have on land-atmosphere
interactions. Subgrid land surface heterogeneity is currently not well
accounted for in land-atmosphere interactions in earth system models.
There have been attempts to include the impact of this heterogeneity on
the atmosphere, but they ignore the development of coherent secondary
circulations that can be driven by spatial differential surface heating.
A wealth of literature, particularly large-eddy simulation (LES) based
studies, shows that these circulations have significant impacts on the
development and organization of clouds. In this work, we describe a
two-column model with a parameterized circulation driven by atmospheric
virtual potential temperature profiles, differences in near surface
temperature between the two columns, patterns of surface heterogeneity,
and the mean background wind. Key aspects of the proposed model
structure are compared with LES output, and the model is then
implemented between two otherwise independent single column models.
While some avenues for improvement exist, when the circulations are
parameterized, we see increased cloud development and realistic changes
to the mean profiles of temperature and moisture. The proposed model
qualitatively matches expectations from the literature and LES, and
points to the potential success of its future implementation in coarse
grid models.