Signatures of nonmigrating tides in CHAMP zonal wind observations
Abstract
The German minisatellite CHAMP, an acronym for Challenging Minisatellite Payload, will be in orbit for 10 years in July 2010. With its onboard accelerometer we are able to derive the zonal wind at about 400 km altitude. The unique continuous and globally distributed measurements have revealed unexpected results. Studying the equatorial zonal wind using four years of data, we found a dominating four-peaked longitudinal structure which could be related to the eastward propagating diurnal tide with zonal wavenumber 3 (DE3). The nonmigrating tide DE3 is excited by latent heat release in deep convective clouds in the tropical troposphere. It was demonstrated that DE3 propagates directly from the troposphere into the upper thermosphere. Recently, the CHAMP accelerometer data have been recalibrated and an extended data set of wind readings is now available starting from June 2001 to December 2007. We will show the tidal spectra for this time period and compare it to the results of Hough Mode Extensions (HMEs) at CHAMP altitude. Possible QBO signatures are planned to be discussed, as well as solar cycle dependencies of the various tides in the upper thermosphere exploring in more detail the coupling mechanisms between the different atmospheric layers.
- Publication:
-
38th COSPAR Scientific Assembly
- Pub Date:
- 2010
- Bibcode:
- 2010cosp...38.1260H