A080-04
Semi-coupling of a Field-scale Resolving Land-surface Model and WRF-LES to Investigate the Influence of Land-surface Heterogeneity on PBL Development

Wednesday, 9 December 2020: 20:55
Virtual
Jason S Simon1, Paul Dirmeyer2, Tyler Waterman1, Finley Hay-Chapman3, Gabriel George Katul4 and Nathaniel W. Chaney5, (1)Duke University, Durham, NC, United States, (2)COLA, Fairfax, VA, United States, (3)George Mason University Fairfax, Fairfax, VA, United States, (4)Nicholas School of the Environment, Duke University, Durham, NC, United States, (5)Duke University, Civil and Environmental Engineering, Durham, NC, United States
Recorded Presentation
Abstract:
Land-surface heterogeneity is a recalcitrant problem in land-surface hydrology because of its connection to boundary conditions in numerical weather prediction (NWP) models. These boundary conditions dictate the development and characteristics of the planetary boundary layer (PBL), the crossing statistics between the PBL height and lifting condensation level, cloud formation, and subsequent rainfall generation. Through this PBL pathway, heterogeneity does have first-order effects on sub-grid scale (SGS) parameterizations for both NWP and climate modeling. Here, large-eddy simulation (LES) with realistic heterogeneous surface-flux fields derived from observations and a high-resolution land-surface model is used to investigate the influence of different aspects of land-surface heterogeneity on the PBL dynamics.

The experiment methodology uses a high-resolution land-surface model (HydroBlocks), spun-up over multiple years using reanalysis data, which is then coupled to the Weather Research and Forecasting (WRF) model for high-resolution LES. These LES experiments are performed over the ARM Southern Great Plains Site atmospheric observatory in Oklahoma during the Summer of 2017 with a grid sized to imitate a single cell in a modern climate model. Cases are considered using both the fully heterogeneous land model as well as using a homogeneous surface with domain-averaged surface values at all grid points, so that the dynamical effects of land-surface heterogeneity on the atmosphere may be isolated. Heterogeneous cases will be considered with increasing complexity in the land-surface model, ultimately considering land cover, soil moisture, lateral flow and river routing, allowing the evaluation of different aspects of the land-surface heterogeneity to be evaluated for their role in atmospheric dynamics. Results are evaluated primarily by the differences in the development of clouds and evolution of turbulent kinetic energy in the PBL.

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