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

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1175/JCLI-D-18-0812.1.

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Authors

Marysa M. Laguë , Gordon B. Bonan, Abigail Swann 

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 which 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 extra-tropics. 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 1K 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 Earths climate.

DOI

https://doi.org/10.31223/osf.io/dbyqu

Subjects

Climate, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Keywords

climate, feedbacks, Ecoclimate, Land-atmospheric Interactions, surface properties

Dates

Published: 2018-12-12 08:36

Last Updated: 2019-06-11 18:51

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License

Academic Free License (AFL) 3.0

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