EMS Annual Meeting Abstracts
Vol. 20, EMS2023-332, 2023, updated on 10 Jan 2024
https://doi.org/10.5194/ems2023-332
EMS Annual Meeting 2023
© Author(s) 2024. This work is distributed under the Creative Commons Attribution 4.0 License.
Atmospheric conditions associated with cold East-Asian orography in climate models
- 1Laboratoire de Météorologie Dynamique / Institut Pierre Simon Laplace, ENS - PSL Université, Ecole Polytechnique - Institut Polytechnique de Paris, Sorbonne Université, CNRS, France
- 2Department of Earth and Environmental Sciences, Università di Milano - Bicocca, Milan, Italy
- 3Institute of Geography, University of Bern, Bern, Switzerland
- 4Consiglio Nazionale delle Ricerche, Istituto di Scienze dell’Atmosfera e del Clima (CNR-ISAC), Torino, Italy
- 5Astronomy and Meteorology Department, Faculty of Science, Cairo University, Cairo, Egypt
- 6Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
East Asia orography, i.e. the elevated Tibetan and Mongolian Plateaux, is of fundamental importance for the mid-latitude climate over the Eastern part of the continent and the Pacific. During winter it supports and strengthens the Siberian (surface-pressure) High and the East-Asia Winter Monsoon, contributing to the advection of dry and cold air over the Asian coast and the Pacific Ocean. While the role of the mechanic forcing by Asian orography has been thoroughly addressed by scientific literature, here we identify the near-surface temperature over East-Asia high plateaux as an additional and important ingredient for setting the winter climate on the lee side of the orography : a cold surface-based heat source on the elevated Asian Plateaux amplifies the atmospheric response to orography (as observed in former modelling studies), causing an intensification of the East Asia winter monsoon and a strengthening of the southern flank of the Pacific jet. This finding is based on the analysis of a composite of climate-model climatologies characterised by cold East-Asian orography (from the Coupled Model Inter-comparison Project, Phase 6 - CMIP6), and is confirmed by running simulations forced by cold land-surface temperatures over the same orographic region, using an intermediate-complexity atmospheric model in perpetual-winter conditions. Our results, ranging over different degrees of model complexity, are in line with the outcomes of a highly idealised analysis of the interaction of the atmosphere with orography and superposed heat sources, in Ringler and Cook (1999). Moreover, the problem is particularly relevant in view of the well known cold bias in state-of-the art climate models - such as the CMIP6 ensemble - in proximity of the Tibetan Plateau.
T. D. Ringler and K. H. Cook. Understanding the seasonality of orographically forced stationary waves: Interaction between mechanical and thermal forcing. Journal of the atmospheric sciences, 56(9):1154–1174, 1999
T. D. Ringler and K. H. Cook. Understanding the seasonality of orographically forced stationary waves: Interaction between mechanical and thermal forcing. Journal of the atmospheric sciences, 56(9):1154–1174, 1999
How to cite: D'Andrea, F., Portal, A., Davini, P., Hamouda, M. E., and Pasquero, C.: Atmospheric conditions associated with cold East-Asian orography in climate models, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-332, https://doi.org/10.5194/ems2023-332, 2023.
