Santanello, Jr. Joseph A., Christa D. Peters-Lidard, National
Aeronautics and Space Administration/GSFC, Aaron D. Kennedy, U. North Dakota,
and Sujay V. Kumar, NASA-GSFC
Land-atmosphere (L-A)
interactions play a critical role in determining the diurnal evolution of land
surface and planetary boundary layer (PBL) temperature and moisture states and
fluxes. In turn, these
interactions regulate the strength of the connection between surface moisture
and precipitation in a coupled system.
To address model deficiencies, recent studies have focused on development
of diagnostics to quantify the strength and accuracy of the land-PBL coupling
at the process-level. In this
paper, a diagnosis of the nature and impacts of local land-atmosphere coupling
(LoCo) during dry and wet extreme conditions is presented using a combination
of models and observations during the summers of 2006 and 2007 in the U.S.
Southern Great Plains. A range of
diagnostics exploring the links and feedbacks between soil moisture and
precipitation are applied to the dry/wet regimes exhibited in this region, and
in the process a thorough evaluation of
nine different land-PBL scheme couplings is conducted under the umbrella
of a high-resolution regional modeling testbed. Results show that the sign and magnitude of errors in land
surface energy balance components are sensitive to the choice of land surface
model, regime type, and running mode.
In addition, LoCo diagnostics show that the sensitivity of L-A coupling
is stronger towards the land during dry conditions, while the PBL scheme coupling
becomes more important during the wet regime. Results also demonstrate how LoCo diagnostics can be applied
to any modeling system (e.g. reanalysis products) in the context of their
integrated impacts on the process-chain connecting the land surface to the PBL
and in support of hydrological anomalies.