High Spatial Resolution Soil Temperatures Simulation over the Northern Hemisphere
Abstract
Soil temperatures are comprehensive indicators of energy, mass, and biogeochemical exchanges in the atmosphere-ground interaction. Their spatial variation provides catch-all information for better understanding climate, ecological, hydrological processes, and the critical indicator for permafrost mapping. Although almost every land surface models simulated ground thermal regime and mostly used parametrization scheme or simplified formulas, together with coarse vertical resolution, shallow bottom boundary, and without unfrozen water. We present a high resolution simulation with a more detailed soil heat transfer model. Here, we utilized GIPL-2.0 model to simulate long-term mean (1971-2000) monthly soil temperatures up to 50 m below the ground surface over the Northern Hemisphere. WorldClimate v2.0 was used to provide a long-term monthly mean air temperature over 1971-2000. Long-term monthly mean snow depth (only averaged over 1998-2017) was obtained from the Canadian Meteorological Centre dataset. A new high-resolution soil database, SoilGrids, was used for soil parameterization for seven soil layers (0-0.05, 0.05-0.15, 0.15-0.30, 0.30-0.60, 0.60-1.00, 1.00-2.00, 2.00-50.0 m) with an assumption of uniform soil properties below 2 m. Thermal properties were estimated from soil texture, bulk density, and water content. Mean annual air temperature was used as a first guess of initial soil temperature conditions. To reduce the influence of initial conditions, the model was run for 100 years to achieve approximate steady state, and only the last year's outputs were used for validation. We compared the simulated soil temperatures with the long-term (1971-2000) monthly mean soil temperatures measurements up to 3.2 m (including 0.20, 0.40, 0.80, 1.60, 3.20 m) from approximately 1000 meteorological stations. Simulated soil temperatures were well correlated with the observations (R2=0.96, p<<0.01), although there was a cool bias of about 1.13 ºC from simulated soil temperatures. We compared mean annual ground temperature at 15 m with the measurements from 592 boreholes in GTN-P network. Measurements at this depth were also indicating a good correlation (R2=0.62, p<<0.01). These validations suggested that the soil thermal parameterization is valid for simulation of ground thermal statues. This study provides a snapshot of current high-resolution monthly soil temperatures over the Northern Hemisphere, which serves as a reliable initial condition for the dynamic simulation. Future works aims to use high-resolution climatic data (e.g., TerraClimate since 1958) for tracking or reconstructing historical soil temperatures evolution over the Northern Hemisphere.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.C33F1631W
- Keywords:
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- 0750 Sea ice;
- CRYOSPHEREDE: 0799 General or miscellaneous;
- CRYOSPHEREDE: 9315 Arctic region;
- GEOGRAPHIC LOCATIONDE: 1621 Cryospheric change;
- GLOBAL CHANGE