The coexistence of gravity waves from diverse sources during a SOUTHTRAC flight

ALEXANDER, P.; DE LA TORRE, A.; LLAMEDO, P.; HIERRO, R.; MARCOS, T.; KAIFLER, B.; KAIFLER, N.; GELDENHUYS, M.; PREUSSE, P.; GIEZ, A.; RAPP, M.; HORMAECHEA, J. L.

Journal of Geophysical Research: Atmospheres

JOHN WILEY AND SONS INC

Año: 2023

2169-897X

We use observations from one of the SOUTHTRAC (Southern HemisphereTransport, Dynamics, and Chemistry) Campaign flights in Patagoniaand the Antarctic Peninsula during September 2019 to analyzepossible sources of gravity wave (GW) in this hotspot during australlate winter and early spring. Data from two of the instrumentsonboard the German High Altitude and Long Range Research Aircraft(HALO) are employed: the Airborne Lidar for Middle Atmosphereresearch (ALIMA) and the Basic HALO Measurement and Sensor System(BAHAMAS). The former provides vertical temperature profiles alongthe trajectory while the latter gives the three components ofvelocity, pressure and temperature at the flight position. GW inducedperturbations are obtained from these observations. We includenumerical simulations from the Weather Research and Forecast (WRF)model to place a four-dimensional context for the GW observed duringthe flight and in order to present possible interpretations of themeasurements, as for example the orientation or eventual propagationsense of the waves may not be inferred using only data obtainedonboard. We first evaluate agreements and discrepancies between themodel outcomes and the observations. This allowed us an assessmentof the WRF performance in the generation, propagation and eventualdissipation of diverse types of GW through the troposphere,stratosphere and lower mesosphere. We then analyze the coexistenceand interplay of mountain waves (MW) and non-orographic (NO) GW. TheMW dominate above topographic areas and in direction of theso-called GW belt whereas the latter waves are mainly relevant aboveoceanic zones.