First tomographic observations of gravity waves by the infrared limb imager GLORIA

• Main Authors: Krisch, Isabell, Preusse, Peter, Strube, Cornelia, Riese, Martin, Ungermann, Jörn, Dörnbrack, Andreas, Eckermann, Stephen D., Ern, Manfred, Friedl-Vallon, Felix, Kaufmann, Martin, Oelhaf, Hermann, Rapp, Markus
• Format: Article in Journal/Newspaper
• Language: English
• Published: EGU 2017
• Subjects: info:eu-repo/classification/ddc/550; Iceland
• Online Access: https://juser.fz-juelich.de/record/838124; https://juser.fz-juelich.de/search?p=id:%22FZJ-2017-06828%22

Atmospheric gravity waves are a major cause of uncertainty in global atmospheric models. This uncertainty affects regional climate projections and seasonal weather predictions. Improving the representation of gravity waves in global atmospheric models, is therefore of primary interest. In this regard, measurements providing an accurate 3-D characterization of gravity waves are needed. Using the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA), the first airborne implementation of a novel infrared limb imaging technique, a gravity wave event over Iceland was measured. An air volume disturbed by this gravity wave, was investigated from different angles by encircling the volume with a closed flight pattern. Using a tomographic retrieval approach the measurements of this air mass under different angles allowed for a 3-D reconstruction of the temperature and trace gas structure. The temperature measurements were used to derive gravity wave amplitudes, 3-D wave vectors, and direction-resolved momentum fluxes. These parameters facilitated the backtracing of the waves to their sources on the south coast of Iceland. Two wave packets are distinguished, one stemming from the main mountain ridge in the South of Iceland, a second one from the smaller mountains in the North. The total, area-integrated fluxes of these two wave packets are determined. Following the waves forward with a ray-tracing model highlighted the importance of 3-D propagation, an effect generally neglected in global atmospheric models.