scholarly journals Closing the scale gap between land surface parameterizations and GCMs with a new scheme, SiB3-Bins

2017 ◽  
Vol 9 (1) ◽  
pp. 691-711 ◽  
Author(s):  
I. T. Baker ◽  
P. J. Sellers ◽  
A. S. Denning ◽  
I. Medina ◽  
P. Kraus ◽  
...  
Keyword(s):  
Land Surface ◽  
Surface Parameterizations

scholarly journals Climate Impacts of Making Evapotranspiration in the Community Land Model (CLM3) Consistent with the Simple Biosphere Model (SiB)

2009 ◽  
Vol 10 (2) ◽  
pp. 374-394 ◽  
Author(s):  
Peter J. Lawrence ◽  
Thomas N. Chase
Keyword(s):  
Climate Sensitivity ◽  
Land Surface ◽  
Climate Modeling ◽  
Land Surface Models ◽  
Surface Hydrology ◽  
Community Land Model ◽  
Wide Range ◽  
Surface Models ◽  
Biosphere Model ◽  
Surface Parameterizations

Abstract In recent climate sensitivity experiments with the Community Climate System Model, version 3 (CCSM3), a wide range of studies have found that the Community Land Model, version 3 (CLM3), simulates mean global evapotranspiration with low contributions from transpiration (15%), and high contributions from soil and canopy evaporation (47% and 38%, respectively). This evapotranspiration partitioning is inconsistent with the consensus of other land surface models used in GCMs. To understand the high soil and canopy evaporation and the low transpiration observed in the CLM3, select individual components of the land surface parameterizations that control transpiration, canopy and soil evaporation, and soil hydrology are compared against the equivalent parameterizations used in the Simple Biosphere Model, versions 2 and 3 (SiB2 and SiB3), and against more recent developments with CLM. The findings of these investigations are used to develop new parameterizations for CLM3 that would reproduce the functional dynamics of land surface processes found in SiB and other alternative land surface parameterizations. Global climate sensitivity experiments are performed with the new land surface parameterizations to assess how the new SiB, consistent CLM land surface parameterizations, influence the surface energy balance, hydrology, and atmospheric fluxes in CLM3, and through that the larger-scale climate modeled in CCSM3. It is found that the new parameterizations enable CLM to simulate evapotranspiration partitioning consistently with the multimodel average of other land surface models used in GCMs, as evaluated by Dirmeyer et al. (2005). The changes in surface fluxes also resulted in a number of improvements in the simulation of precipitation and near-surface air temperature in CCSM3. The new model is fully coupled in the CCSM3 framework, allowing a wide range of climate modeling investigations without the surface hydrology issues found in the current CLM3 model. This provides a substantially more robust framework for performing climate modeling experiments investigating the influence of land cover change and surface hydrology in CLM and CCSM than the existing CLM3 parameterizations. The study also shows that changes in land surface hydrology have global scale impacts on model climatology.

Predictability of Precipitation in Complex Terrain using the WRF Model with Varying Physics Parameterizations

2020 ◽  
Author(s):  
Julia Jeworrek ◽  
Gregory West ◽  
Roland Stull
Keyword(s):  
Land Surface ◽  
Complex Terrain ◽  
Weather Prediction ◽  
Wrf Model ◽  
The Other ◽  
Convective Precipitation ◽  
Annual Rainfall ◽  
Hourly Precipitation ◽  
Physics Parameterizations ◽  
Surface Parameterizations

<p>Canada’s west coast topography plays a crucial role for the local precipitation patterns, which are often shaped by orographic lifting on one side of the mountains, and rain shadows on the other side. The hydroelectric infrastructure in southwest British Columbia (BC) relies heavily on the abundant rainfall of the wet season, but long lasting and heavy precipitation can cause local flooding and make reliable precipitation forecasts crucial for resource management, risk assessment, and disaster mitigation.</p><p>This research evaluates hourly precipitation forecasts from the Weather Research and Forecasting (WRF) model over the complex terrain of southwest BC. The model data includes a full year of daily runs across three nested domains (27-9-3 km). A selection of different parameterizations is systematically varied, including microphysics, cumulus, turbulence, and land-surface parameterizations. The resulting over 100 model configurations are evaluated with observations from ground-based quality-controlled precipitation gauges. The individual model skill of the precipitation forecasts is assessed with respect to different accumulation windows, forecast horizons, grid resolutions, and precipitation intensities. Furthermore, the ensemble mean and spread provide insight to the general error growth for precipitation forecasts in WRF.</p><p>Cumulus and microphysics parameterizations together determine the total precipitation in numerical weather prediction models and this study confirms the expectation that the combination of those physics parameterizations is most decisive for the precipitation forecasts. However, the boundary-layer and land-surface parameterizations have a secondary effect on precipitation skill. The verification shows that the WSM5 microphysics parameterization yields surprisingly competitive verification scores when compared to more sophisticated and computationally expensive parameterizations. Although, the scale-aware Grell-Freitas cumulus parameterization performs better for summer-time convective precipitation, the conventional Kain-Fritsch parameterization performs better for winter-time frontal precipitation, which contributes to the majority of the annual rainfall in southwest BC.</p><p>Throughout a 3-day forecast horizon mean absolute errors are observed to grow by ~5% per forecast day. Furthermore, this study indicates that coarser resolutions suffer from larger total biases and larger random error components, however, they have slightly higher correlation coefficients. The mid-size 9-km domain yields the highest relative hit rate for significant and extreme precipitation. Verification metrics improve exponentially with longer accumulation windows: On one side, hourly precipitation values are highly prone to double-penalty issues (where a timing error can, for example, result in an over-forecast error in one hour and an under-forecast in a subsequent hour); on the other side, extended accumulation windows can compensate for timing errors, but lose information about short-term rain intensities.</p>

Role of land surface parameterizations on modeling cold-pooling events and low-level jets

2011 ◽  
Vol 99 (1) ◽  
pp. 147-161 ◽  
Author(s):  
Thara V. Prabha ◽  
Gerrit Hoogenboom ◽  
Tatiana G. Smirnova
Keyword(s):  
Land Surface ◽  
Low Level ◽  
Low Level Jets ◽  
Surface Parameterizations

scholarly journals Use of the Richards equation in land surface parameterizations

1999 ◽  
Vol 104 (D22) ◽  
pp. 27519-27526 ◽  
Author(s):  
Deborah H. Lee ◽  
Linda M. Abriola
Keyword(s):  
Land Surface ◽  
Richards Equation ◽  
Surface Parameterizations
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