Flow Regimes and Föhn Types Characterize the Local Climate of Southern Patagonia

Temme F, Turton J, Mölg T, Sauter T (2020)


Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2020

Journal

Book Volume: 11

Pages Range: 899

Journal Issue: 9

DOI: 10.3390/atmos11090899

Open Access Link: https://www.mdpi.com/2073-4433/11/9/899

Abstract

The local climate in Southern Patagonia is strongly influenced by the interaction between the topography and persistent westerlies, which can generate foehn events, dry and warm downslope winds. The upstream flow regime influences different foehn types which dictate the lee-side atmospheric response regarding the strength, spatial extent and phenomenology. We use a combination of observations from four automatic weather stations (AWSs) and high-resolution numerical modeling with the Weather Research and Forecasting (WRF) model for a region in Southern Patagonia (48 ° S – 52 ° S, 72 ° W – 76.5 ° W) including the Southern Patagonian Icefield (SPI). The application of a föhn identification algorithm to a 10-month study period (June 2018 – March 2019) reveals 81 föhn events in total. A simulation of three events of differing flow regimes (supercritical, subcritical, transition) suggests that a supercritical flow regime leads to a linear foehn event with a large spatial extent but moderate intensity. In contrast, a spatially limited but locally strong foehn response is induced by a subcritical regime with upstream blocking and by a transition regime with a hydraulic jump present. Our results imply that the hydraulic jump-type foehn event (transition case) is the most critical for glacier mass balances since it shows the strongest warming, drying, wind velocities and solar radiation over the SPI. The consideration of flow regimes over the last 40 years shows that subcritical flow occurs most frequently (78%), however transitional flow occurs 14% of the time, implying the potential impact on Patagonian glaciers.

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How to cite

APA:

Temme, F., Turton, J., Mölg, T., & Sauter, T. (2020). Flow Regimes and Föhn Types Characterize the Local Climate of Southern Patagonia. Atmosphere, 11(9), 899. https://dx.doi.org/10.3390/atmos11090899

MLA:

Temme, Franziska, et al. "Flow Regimes and Föhn Types Characterize the Local Climate of Southern Patagonia." Atmosphere 11.9 (2020): 899.

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