Wave Modulation of the Extratropical Tropopause Inversion Layer.

Pilch Kedzierski, Robin , Matthes, Katja and Bumke, Karl (2017) Wave Modulation of the Extratropical Tropopause Inversion Layer. Open Access Atmospheric Chemistry and Physics, 17 . pp. 4093-4114. DOI 10.5194/acp-17-4093-2017.

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This study aims to quantify how much of the extratropical Tropopause Inversion Layer (TIL) comes from the modulation by planetary and synoptic-scale waves. By analyzing high-resolution observations, it also puts other TIL enhancing mechanisms into context.

Using gridded COSMIC GPS-RO temperature profiles from 2007–2013 we are able to extract the extratropical wave signal by a simplified wavenumber-frequency domain filtering method, and to quantify the resulting TIL enhancement. By subtracting the extratropical wave signal, we show how much of the TIL is associated with other processes, at mid and high latitudes, for both Hemispheres and all seasons.

The instantaneous modulation by planetary and synoptic-scale waves is almost entirely responsible for the TIL in mid-latitudes. This means that wave-mean flow interactions, inertia-gravity waves or the residual circulation are of minor importance in mid-latitudes.

At polar regions, the extratropical wave modulation is dominant for the TIL strength as well, but there is also a clear fingerprint from sudden stratospheric warmings (SSWs) and final warmings in both hemispheres. Therefore, polar vortex breakups are partially responsible for the observed polar TIL strength in winter (if SSWs occur) and spring. Also, part of the polar summer TIL strength cannot be explained by extratropical wave modulation.

After many modelling studies that proposed different TIL enhancing mechanisms in the last decade, our study finally identifies which processes dominate the extratropical TIL strength and their relative contribution, by analyzing observations only. It remains to be determined, however, which roles the different planetary and synoptic-scale wave types play within the total extratropical wave modulation of the TIL; and what causes the observed amplification of extratropical waves near the tropopause.

Document Type: Article
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
Refereed: Yes
Open Access Journal?: Yes
Publisher: Copernicus Publications (EGU)
Projects: NATHAN, Future Ocean
Date Deposited: 06 Sep 2016 05:58
Last Modified: 06 Feb 2020 09:10
URI: https://oceanrep.geomar.de/id/eprint/33714

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