Is the Tibetan Plateau important for the global monsoon?

It has been hypothesized that large-scale topographic changes such as the surface uplift of the Tibetan Plateau impacts the development of the Indian and East Asian monsoons and can have teleconnected influences on other monsoon regions. However, recent modeling has shown that spatial distribution of the global monsoon, which includes the Indian and East Asian monsoons are largely unaffected by the elevation of the plateau. In this study, we present results from slab-ocean, modern simulations using the CESM1, where the Tibetan Plateau height is varied. The maximum plateau elevation was double the modern plateau height (~8000 m), and minimum elevations were near sea level (~10 m). Introducing a higher plateau into the Asian continent regionally impacts the intensity of the Asian Monsoons and the North African monsoon, but has negligible effects on other monsoon circulations. While reducing plateau elevation poses minor enhancement on the Asian monsoon circulation, such decrease in topography induces negligible effects on other monsoon circulations. Furthermore, changes in surface wind distributions with both doubling and reducing topography are limited to the northern hemisphere (NH) and mainly the vicinity of the Tibetan Plateau. During the NH summer months (JJA), doubling of topography enhances surface winds directed from the tropics, toward Asia. In contrast, reduction of topography induces JJA surface winds to weaken on the Asian continent. In general, we find that using a monsoon index based on the ratio of summer precipitation to annual precipitation, the Indian and East Asian monsoons exists regardless of the Tibetan Plateau's height and that the global monsoon distribution do not change substantially due to plateau elevation changes.