Submitted as: development and technical paper
07 Jun 2022
Submitted as: development and technical paper | 07 Jun 2022
Status: this preprint is currently under review for the journal GMD.

Climate Impacts of Parameterizing Subgrid Variation and Partitioning of Land Surface Heat Fluxes to the Atmosphere with the NCAR CESM1.2

Ming Yin1, Yong Wang1, Wenqi Sun1, Jianbo Deng1,2, Daoming Wei1, Ying Kong3, and Bin Wang1,4,5 Ming Yin et al.
  • 1Department of Earth System Science, Ministry of Education Key Laboratory for Earth System Modeling, Institute for Global Change Studies, Tsinghua University, Beijing, 100084 China
  • 2Hunan Institute of Meteorological Sciences, Changsha, 410118 China
  • 3College of Atmospheric Sciences, Lanzhou University, Lanzhou, 730000 China
  • 4State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029 China
  • 5College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100029 China

Abstract. All current global climate models (GCMs) only utilize grid-averaged surface heat fluxes to drive the atmosphere, and thus, their subgrid horizontal variations and partitioning are absent. This can result in many simulation biases. To address this shortcoming, a novel parameterization scheme considering the subgrid variations of the sensible and latent heat fluxes to the atmosphere and the associated partitioning is developed and implemented into the National Center for Atmospheric Research (NCAR) Climate Earth System Model 1.2 (CESM1.2). The evaluations show that in addition to the improved boreal summer precipitation simulation over eastern China and the coastal areas of the Bay of Bengal, the longstanding overestimations of precipitation on the southern and eastern margins of the Tibetan Plateau (TP) in most GCMs are significantly mitigated. The improved precipitation simulation on the southern and eastern margins of the TP is from suppressed large-scale precipitation. Moisture advection for precipitation production is blocked toward the southern edge of the TP, and the intensity of the moisture transport to the eastern edge is weakened. The corrected large-scale circulation in the lower atmosphere due to the realistic simulations of the grid-scale surface radiative and heat fluxes is responsible for the change in moisture transport. In terms of global annual mean states, some improvements are obtained by the new scheme compared to the default CESM1.2 and the scheme stochastically allocating the subgrid surface heat fluxes to the atmosphere (i.e., without subgrid partitioning included). This study highlights the importance of subgrid surface energy variations and partitioning to the atmosphere in the simulation of the hydrological and energy cycles in GCMs.

Ming Yin 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-2022-114', Anonymous Referee #1, 01 Jul 2022
  • RC2: 'Comment on gmd-2022-114', Anonymous Referee #2, 05 Jul 2022

Ming Yin et al.

Data sets

The Tropical Rainfall Measuring Mission (TRMM) observations (0.25°×0.25°) Huffman et al.

The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) reanalysis (0.5°×0.625°) Gelaro et al.;

The surface radiative fluxes from the Clouds and the Earth’s Radiation Energy Systems (CERES) Energy Balanced and Filled (1.0°×1.0°) (EBAF) Loeb et al.

The sensible heat and latent heat fluxes from the Global Land Data Assimilation System Version 2.1 (GLDAS-2.1) Noah monthly data (1.0°×1.0°) Rodell et al.

2 m air temperature from the Climatic Research Unit with a 0.5° resolution (CRU) Harris et al.

The modified CESM code as well as the CAM5 output for all simulations in the study Yong Wang and Wenqi Sun

Model code and software

The CESM1.2.1-CAM5.3 source code CESM Software Engineering Group (CSEG)

The modified CESM code Yong Wang and Wenqi Sun

Ming Yin et al.


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Short summary
All global climate models (GCMs) use the grid-averaged surface heat fluxes to drive the atmosphere, and thus their horizontal variations within the grid cell are averaged out. In this regard, a novel scheme considering the variation and partitioning of the surface heat fluxes within the grid cell is developed. The scheme reduces the long-standing rainfall biases on the southern and eastern margins of the Tibetan Plateau. In terms of global annual mean statistics, more improvements are obtained.