Yesterday night, HALO completed the fourth research flight dedicated to mountain waves above the Southern Andes. Prevailing moderate westerly to south-westerly winds triggered mountain waves and the flight crew could report “nice” up- and downward movements of the aircraft shortly after take-off along the first cross mountain section.

Large scale gravity waves structures presumably related to exit region of the stratospheric polar night jet were sampled by ALIMA higher up in the stratosphere.

Icing problems of the lidar window which were encountered during the previous flight have not been a problem during this flight. Drying the air in the telescope with Nitrogen and warmer outside temperatures fixed the issue during the flight for this time. In-situ trace gas instruments took measurements of polar vortex air at different latitudes.

Today is a ground day for aircraft and instrument maintenance. The flight plan for the next gravity wave night flight with take-off planned for Friday at 20 LT was already finalized submitted yesterday. Looking forward to another flight with mountain waves forecasted in the troposphere and stratosphere above the Southern Andes.