Department of Geosciences, University of Oslo, Oslo, 0315, Norway
Abstract. We implement a sub-grid representation of excess ground ice within permafrost soils and its melting using the latest version of Community Land Model (CLM5). Based on the original CLM5 tiling hierarchy, we duplicate the natural vegetated landunit by building extra tiles for up to three different excess ice conditions in each grid point. Single-grid simulation cases initialize the same amount of excess ice in same soil layers, while prescribing different volumetric ice contents and sub-grid distributions. For the same total amount of excess ice initialized at the same soil layers, different sub-grid variability of excess ice leads to different excess ice melting rates on the grid level, as well as to different impacts to permafrost thermal properties and local hydrology. We prescribed a tiling scheme based on the dataset “Circum-Arctic Map of Permafrost and Ground-Ice Conditions” (Brown et al., 2002) within horizontal and vertical distributions of three different types of excess ice in the CLM grid to test applicability of sub-grid representation. Compared to the excess ice initialized homogeneously in each grid, the sub-grid scale excess ice and the tiling scheme amend the overly early timing of initial melting and the overly high melting rate of excess ice in warming climate. Initializing the excess ice depths according to local active layer thickness reduces underestimation of excess ice melt for the Arctic coastal regions. Further developments rely on additional global observational datasets on both the spatial and vertical distributions of excess ground ice, where our development of sub-grid representation demonstrated the potential for more realistically projecting excess ice melt in the circum-Arctic domain.
This preprint has been withdrawn.
How to cite. Cai, L., Lee, H., Westermann, S., and Aas, K. S.: Projecting Circum-Arctic Excess Ground Ice Melt with a sub-grid representation in the Community Land Model, The Cryosphere Discuss. [preprint], https://doi.org/10.5194/tc-2019-230, 2019.
Received: 29 Sep 2019 – Discussion started: 07 Oct 2019
We develop a sub-grid representation of excess ground ice in the Community Land Model (CLM) by adding three landunits to the original CLM sub-grid hierarchy, in order to prescribe three different excess ice conditions in one grid cell. Single-grid simulations verify the potential of the model development on better projecting excess ice melt in a warming climate. Global simulations recommend the proper way of applying the model development with the existing excess ice dataset.
We develop a sub-grid representation of excess ground ice in the Community Land Model (CLM) by...