Scales of Surface Heterogeneity Affecting the Daytime Convective
Atmosphere over Land
- Paul A Dirmeyer,
- Finley Miles Hay-Chapman,
- Jason Scot Simon,
- Nathaniel W. Chaney
Abstract
Coupled land-atmosphere models exchange grid cell mean values of states
and fluxes even as they separately simulate subgrid variability. The
characteristics of atmospheric heterogeneity driven by land surface
heterogeneity are examined in large eddy simulations. The degree of
spatial variance in the atmosphere is highly correlated with the spatial
variance of land surface fluxes, but the impacts are entirely at scales
larger than 10-30 km. Between 1-10 km throughout most of the day there
is no difference in power spectra over heterogeneous and homogeneous
surfaces, as synoptic situations and internal dynamics associated with
atmospheric turbulent transfer is insensitive to surface heterogeneity.
To improve forecasts, the ability of land surface heterogeneity to
organize mesoscale circulations affecting boundary layer evolution and
convective development should be represented in non-cloud-resolving
models, as modern convective parameterizations can account for such
subgrid processes. This will require the exchange of subgrid information
between land and atmosphere models.13 Nov 2024Submitted to ESS Open Archive 13 Nov 2024Published in ESS Open Archive