Joint Seminar: Impact of improved land model depth and soil hydro-thermic coupling on climate change projections and permafrost response

The representation of the terrestrial thermal and hydrological state in Land Surface Models is crucial in order to have a realistic simulation of the coupling between the atmosphere and the lito-/bio-sphere. Many current-generation climate models have land models with a depth of 10m, which is too shallow. This distorts the energy storage and distribution in the ground and can have implications for the representation of land-air interactions. Therefore, we introduce a deeper bottom boundary condition placement into JSBACH which increases its depth from 10m to 1400m. The newly established terrestrial thermal state of the deep JSABCH may influence the near-surface hydroclimate when sufficient coupling between the thermal and hydrological regimes is present. We therefore also assess the influence of introducing various physical modifications for the representation of hydro-thermal processes in climate projections of the 21st century with the deep JSBACH, particularly important for cold regions where freezing and thawing processes take place. Under climate change conditions, these areas are prone to release substantial amounts of carbon into the atmosphere from degrading permafrost soils. The results show important impacts on regional terrestrial energy uptake by more than one order of magnitude, as well as significant changes in near-surface ground temperature and soil moisture patterns when introducing the physical modifications. The resulting simulation of permafrost extent is subject to large variations depending on the model configuration, reflecting the uncertainty of carbon release from permafrost degradation that still exists in state-of-the-art Land Surface Models.

Date

09.02.2021

Time

15:15–16:15 h

Place

Virtual Seminar
Hamburg

Speaker

Norman Steinert, Universidad Complutense de Madrid

Organizers

Dian Putrasahan

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