Mountain Wave Climatology at Cerro Pachón, Chile, from All Sky Imager Analysis

Abstract:

All Sky OH airglow images obtained from 2009-2014 at the Andes Lidar Observatory (ALO) located in Cerro Pachón, Chile (30ºS, 71ºW) are used to identify the occurrence of mountain waves. The ALO is located in the Andes, where mountain waves are frequently generated. The large field-of-view of an All Sky imager provides extensive sky coverage for identifying mountain waves, making them a prime instrument for observing these waves that extend hundreds of kilometers along the mesosphere. A total of about 70 waves were identified each year. Based on these observations, mountain wave climatology over ALO is complied. It is found that there are markedly more mountain waves in the winter season than in the summer. Most mountain waves are oriented in the North-South direction, along the mountain range, as expected from the orientation of the Andes. The strength and frequency of the mountain waves are correlated with the low-level wind obtained from radio sonde data.