High-resolution modelling of interactions between soil moisture and convective development in a mountain enclosed Tibetan Basin
Hydrology and Earth System Sciences
European Geosciences Union
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Gerken, T., Babel, W., Herzog, M., Fuchs, K., Sun, F., Ma, Y., Foken, T., & et al. (2015). High-resolution modelling of interactions between soil moisture and convective development in a mountain enclosed Tibetan Basin. Hydrology and Earth System Sciences, 19 4023-4040. https://doi.org/10.5194/hess-19-4023-2015
The Tibetan Plateau plays a significant role in atmospheric circulation and the Asian monsoon system. Turbulent surface fluxes and the evolution of boundary-layer clouds to deep and moist convection provide a feedback system that modifies the plateau's surface energy balance on scales that are currently unresolved in mesoscale models. This work analyses the land surface's role and specifically the influence of soil moisture on the triggering of convection at a cross section of the Nam Co Lake basin, 150 km north of Lhasa using a cloud-resolving atmospheric model with a fully coupled surface. The modelled turbulent fluxes and development of convection compare reasonably well with the observed weather. The simulations span Bowen ratios of 0.5 to 2.5. It is found that convective development is the strongest at intermediate soil moisture. Dry cases with soils close to the permanent wilting point are moisture limited in convective development, while convection in wet soil moisture cases is limited by cloud cover reducing incoming solar radiation and sensible heat fluxes, which has a strong impact on the surface energy balance. This study also shows that local development of convection is an important mechanism for the upward transport of water vapour, which originates from the lake basin that can then be transported to dryer regions of the plateau. Both processes demonstrate the importance of soil moisture and surface–atmosphere interactions on the energy and hydrological cycles of the Tibetan Plateau.
This research was funded by the German Research Foundation (DFG) Priority Programme 1372 “Tibetan Plateau: Formation, Climate, Ecosystems” as part of the Atmosphere–Ecology–Glaciology–Cluster (TiP-AEG): FO 226/18- 1,2. The work described in this publication has been supported by the European Commission (Call FP7-ENV-2007-1 grant no. 212921) as part of the CEOP-AEGIS project coordinated by the University of Strasbourg. The map of Nam Co was produced by Sophie Biskop (University of Jena) and Jan Kropacek (University of Tübingen) within DFG-TiP and Phil Stickler of the Cambridge Geography Department Cartography Unit. This publication was funded by the German Research Foundation (DFG) and the University of Bayreuth in the funding programme Open-Access Publishing.
External DOI: https://doi.org/10.5194/hess-19-4023-2015
This record's URL: https://www.repository.cam.ac.uk/handle/1810/252331
Attribution 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by/2.0/uk/
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