Seminars

Lecturer: P. Preusse, S. Gisinger, I. Krisch, Forschungszentrum Jülich and DLR, Germany
Date: 2016-03-08 10:30
Place: Aniara

Gravity wave measurements in the frame of the GW-LCycle project

Gravity waves (GWs) can exist in any stably stratified medium with gravity / buoyancy as the restoring force. They exist in the atmosphere of most planets including the Earth. There they have horizontal scales of a few kilometers up to thousand kilometers and longer. From their sources GWs frequently propagate upwards and deposit energy and momentum when dissipating. The resulting acceleration is a major driver of the circulation in the middle atmosphere. In general circulation models (GCMs) employed for weather forecast and climate projection GWs are either completely parameterized or, if resolved by the model, strongly depend on parameterizations. We therefore require both better knowledge on the global distributions as well as improved understanding of the processes related to the excitation, propagation and dissipation of gravity waves. Improving process understanding in winter conditions is the aim of the GW-LCycle project coordinated by Markus Rapp and Andreas Dornbrack (DLR). By means of aircraft, ground-based and satellite measurements, GWs shall be observed and characterized at various altitudes from the troposphere to the upper mesosphere, that is during the whole GW life cycle of source, propagation and dissipation. For GW-Lcycle dedicated measurements flights were performed in northern Scandinavia in December 2013, in New Zealand in June and July 2014 (ground based lidar June-Sept 2014) and, in the current winter, from the base in Kiruna. In particular, the German research aircraft HALO and DLR's Falcon provide a unique combination of different instruments. We will show results from all three campaigns with a focus on the ongoing campaign from Kiruna. In this phase, gravity waves were excited due to a complex interplay of jet instability and orography. We will show how different instruments see these wave events and give an outlook on the furture evaluation.

Created 2016-02-26 16:23:56 by Uwe Raffalski
Last changed 2016-03-02 18:26:45 by Uwe Raffalski