Separating the Impact of Individual Land Surface Properties on the Terrestrial Surface Energy Budget in both the Coupled and Uncoupled Land–Atmosphere System

Abstract Changes in the land surface can drive large responses in the atmosphere on local, regional, and global scales. Surface properties control the partitioning of energy within the surface energy budget to fluxes of shortwave and longwave radiation, sensible and latent heat, and ground heat storage. Changes in surface energy fluxes can impact the atmosphere across scales through changes in temperature, cloud cover, and large-scale atmospheric circulation. We test the sensitivity of the atmosphere to global changes in three land surface properties: albedo, evaporative resistance, and surface roughness. We show the impact of changing these surface properties differs drastically between simulations run with an offline land model, compared to coupled land–atmosphere simulations that allow for atmospheric feedbacks associated with land–atmosphere coupling. Atmospheric feedbacks play a critical role in defining the temperature response to changes in albedo and evaporative resistance, particularly in the extratropics. More than 50% of the surface temperature response to changing albedo comes from atmospheric feedbacks in over 80% of land areas. In some regions, cloud feedbacks in response to increased evaporative resistance result in nearly 1 K of additional surface warming. In contrast, the magnitude of surface temperature responses to changes in vegetation height are comparable between offline and coupled simulations. We improve our fundamental understanding of how and why changes in vegetation cover drive responses in the atmosphere, and develop understanding of the role of individual land surface properties in controlling climate across spatial scales—critical to understanding the effects of land-use change on Earth’s climate.

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Separating the impact of individual land surface properties on the terrestrial surface energy budget in both the coupled and un-coupled land-atmosphere system

10.31223/osf.io/dbyqu ◽

2018 ◽

Author(s):

Marysa Laguë ◽

Gordon Bonan ◽

Abigail Swann

Keyword(s):

Surface Energy ◽

Surface Properties ◽

Energy Budget ◽

Land Surface ◽

Surface Energy Budget ◽

Atmosphere System ◽

The Impact

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The improvement of soil thermodynamics and its effects on land surface meteorology in the IPSL climate model

Geoscientific Model Development ◽

10.5194/gmd-9-363-2016 ◽

2016 ◽

Vol 9 (1) ◽

pp. 363-381 ◽

Cited By ~ 16

Author(s):

F. Wang ◽

F. Cheruy ◽

J.-L. Dufresne

Keyword(s):

Soil Moisture ◽

Thermal Properties ◽

Surface Energy ◽

Surface Temperature ◽

Energy Budget ◽

Land Surface ◽

Climate Model ◽

Surface Energy Budget ◽

Dry Areas ◽

Soil Thermal Properties

Abstract. This paper describes the implementation of an improved soil thermodynamics in the hydrological module of Earth system model (ESM) developed at the Institut Pierre Simon Laplace (IPSL) and its effects on land surface meteorology in the IPSL climate model. A common vertical discretization scheme for the soil moisture and for the soil temperature is adopted. In addition to the heat conduction process, the heat transported by liquid water into the soil is modeled. The thermal conductivity and the heat capacity are parameterized as a function of the soil moisture and the texture. Preliminary tests are performed in an idealized 1-D (one-dimensional) framework and the full model is then evaluated in the coupled land–atmospheric module of the IPSL ESM. A nudging approach is used in order to avoid the time-consuming long-term simulations required to account for the natural variability of the climate. Thanks to this nudging approach, the effects of the modified parameterizations can be modeled. The dependence of the soil thermal properties on moisture and texture lead to the most significant changes in the surface energy budget and in the surface temperature, with the strongest effects on the surface energy budget taking place over dry areas and during the night. This has important consequences on the mean surface temperature over dry areas and during the night and on its short-term variability. The parameterization of the soil thermal properties could therefore explain some of the temperature biases and part of the dispersion over dry areas in simulations of extreme events such as heat waves in state-of-the-art climate models.

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The improvement of soil thermodynamics and its effects on land surface meteorology in the IPSL climate model

Geoscientific Model Development Discussions ◽

10.5194/gmdd-8-8411-2015 ◽

2015 ◽

Vol 8 (10) ◽

pp. 8411-8450

Author(s):

F. Wang ◽

F. Cheruy ◽

J.-L. Dufresne

Keyword(s):

Soil Moisture ◽

Thermal Properties ◽

Surface Energy ◽

Surface Temperature ◽

Energy Budget ◽

Land Surface ◽

Climate Model ◽

Surface Energy Budget ◽

Dry Areas ◽

Soil Thermal Properties

Abstract. This paper describes the implementation of an improved soil thermodynamics in the hydrological module of Earth System Model (ESM) developed at the Institut Pierre Simon Laplace (IPSL) and its effects on land surface meteorology in the IPSL climate model. A common vertical discretization scheme for the soil moisture and for the soil temperature is adopted. In addition to the heat conduction process, the heat transported by liquid water into the soil is modeled. The thermal conductivity and the heat capacity are parameterized as a function of the soil moisture and the texture. Preliminary tests are performed in an idealized 1-D framework and the full model is then evaluated in the coupled land/atmospheric module of the IPSL ESM. A nudging approach is used in order to avoid the time-consuming long-term simulations required to account for the natural variability of the climate. Thanks to this nudging approach, the effects of the modified parameterizations can be modeled. The dependence of the soil thermal properties on moisture and texture lead to the most significant changes in the surface energy budget and in the surface temperature, with the strongest effects on the surface energy budget taking place over dry areas and during the night. This has important consequences on the mean surface temperature over dry areas and during the night and on its short-term variability. The parameterization of the soil thermal properties could therefore explain some of the temperature biases and part of the dispersion over dry areas in simulations of extreme events such as heat waves in state-of-the-art climate models.

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Quantifying the Impacts of Land Surface Modeling on Hub-Height Wind Speed under Different Soil Conditions

Monthly Weather Review ◽

10.1175/mwr-d-20-0363.1 ◽

2021 ◽

Author(s):

Geng Xia ◽

Caroline Draxl ◽

Larry K. Berg ◽

David Cook

Keyword(s):

Wind Speed ◽

Surface Energy ◽

Energy Budget ◽

Land Surface ◽

Frozen Soil ◽

Surface Energy Budget ◽

Soil Conditions ◽

Modeling Uncertainties ◽

Dry Soil ◽

The Impact

AbstractWe investigate the impact of three land surface models (LSMs) on simulating hub-height wind speed under three different soil regimes (dry, wet, and frozen) to improve understanding of the physics of wind energy forecasts using the Weather Research and Forecasting (WRF) model. A six-day representative period is selected for each soil condition. The simulated wind speed, surface energy budget and soil properties are compared with the observations collected from the second Wind Forecast Improvement Project (WFIP2). For the selected cases, our simulation results suggest that the impact of LSMs on hub-height wind speed are sensitive to the soil states but not so much to the choice of LSM. The simulated hub-height wind speed is in much better agreement with the observations for the dry soil case than the wet and frozen soil cases. Over the dry soil, there is a strong physical connection between the land surface and hub-height wind speed through near-surface turbulent mixing. Over the wet soil, the simulated hub-height wind speed is less impacted by the land surface due to weaker surface fluxes and large-scale synoptic disturbances. Over the frozen soil, the LSM seems to have limited impact on hub-height wind speed variability due to the decoupling of the land surface with the overlying atmosphere. Two main sources of modeling uncertainties are proposed. The first is the insufficient model physics representing the surface energy budget, especially the ground heat flux, and the second is the inaccurate initial soil states such as soil temperature and soil moisture.

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