Publication Date:
2023-06-13
Description:
The Hengduan Mountains (HM) are located on the southeasternmost fringe of the Tibetan Plateau and reveal an exceptionally high biodiversity, which is believed to be the result of past complex interactions between tectonic uplift, land surface dynamics and climate. To investigate the role of HM geometry on monsoon-dominated climate, we performed simulations with the regional and non-hydrostatic climate model COSMO at 12 and 4.4 km grid spacings. We consider two idealised terrain perturbations, which are linked to past states of the Hengduan mountain ranges. In the first experiment, we reduce topography in a spatially non-uniform way, in which the southern foothills of the HM are completely flattened (representing the uplift that happened about 10 Ma ago). The results show that the uplift of the HM intensified precipitation in Indochina and southwestern China. Besides, the cyclonic circulation in the Bay of Bengal extended eastward, indicating an intensification of the East Asian summer monsoon. In a second experiment, we remove the deep valleys by applying an envelope topography to quantify the effects of these features on the local climate (representing the role of valley erosion). This experiment resulted in decreased precipitation (and runoff) over the HM, suggesting a positive precipitation-erosion feedback mechanism. In the next step, we study the relevance of the HM mountains on regional and larger-scale climate for the past by performing high-resolution COSMO simulations for the Last Glacial Maximum (~21’000 years ago) and a phase in the mid-Pliocene (~3 Ma ago).
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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