Preprints
https://doi.org/10.5194/gmd-2021-421
https://doi.org/10.5194/gmd-2021-421
Submitted as: development and technical paper
08 Feb 2022
Submitted as: development and technical paper | 08 Feb 2022
Status: this preprint is currently under review for the journal GMD.

Representing surface heterogeneity in land-atmosphere coupling in E3SMv1 single-column model over ARM SGP during summertime

Meng Huang1, Po-Lun Ma1, Nathaniel W. Chaney2, Dalei Hao1, Gautam Bisht1, Megan D. Fowler3, Vincent E. Larson1,4, and L. Ruby Leung1 Meng Huang et al.
  • 1Pacific Northwest National Laboratory, Richland, WA, USA
  • 2Department of Civil and Environmental Engineering, Duke University, Durham, NC, USA
  • 3National Center for Atmospheric Research, Boulder, CO, USA
  • 4Department of Mathematical Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA

Abstract. The Earth's land surface features spatial and temporal heterogeneity over a wide range of scales below those resolved by current Earth system models. State-of-the-art land and atmosphere models employ parameterizations to represent their subgrid heterogeneity, but the land-atmosphere coupling in ESMs typically operates on the grid scale. Communicating the information of the land surface heterogeneity with the overlying atmospheric boundary layer (ABL) remains a challenge in modeling land-atmosphere interactions. In order to account for the subgrid scale heterogeneity in land-atmosphere coupling, we implement a new coupling scheme in the Energy Exascale Earth System Model version 1 (E3SMv1) that uses adjusted surface variances and covariance of potential temperature and specific water content as the lower boundary condition for the atmosphere model. The new lower boundary condition accounts for both the variability of individual subgrid land surface patches and the inter-patch variability. E3SMv1 single-column model simulations over the Atmospheric Radiation Measurement (ARM) Southern Great Plain (SGP) site were performed to assess the impacts. We find that the new coupling parameterization increases the magnitude and diurnal cycle of the temperature variance and humidity variance in the lower ABL in non-precipitating days. The impacts are primarily attributed to subgrid inter-patch variability rather than variability of individual patches. These effects extend vertically from the surface to several levels in the lower ABL on clear days. We also find that accounting for surface heterogeneity increases low cloud cover and liquid water path. These cloud changes are associated with the change in cloud regime indicated by the skewness of the probability density function (PDF) of the subgrid vertical velocity. In precipitating days, the inter-patch variability reduces significantly, so that the impact of accounting for surface heterogeneity vanishes. These results highlight the importance of accounting for subgrid heterogeneity in land-atmosphere coupling in next generation Earth system models.

Meng Huang et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2021-421', Anonymous Referee #1, 29 Mar 2022
  • RC2: 'Comment on gmd-2021-421', Anonymous Referee #2, 10 Apr 2022

Meng Huang et al.

Data sets

E3SM single column model output Meng Huang https://doi.org/10.5281/zenodo.5787518

Model code and software

Energy Exascale Earth System Model v1.0 E3SM Project, DOE https://doi.org/10.11578/E3SM/dc.20180418.36

Meng Huang et al.

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Short summary
The land surface in one grid cell may be diverse in character. This study uses an explicit way to account for that subgrid diversity in a state-of-the-art Earth system model and explores its implications for the overlying atmosphere. We find the shallow clouds are increased significantly with the land surface diversity. Our work highlights the importance of accurately representing the land surface and its interaction with the atmosphere in next generation Earth system models.