Buoyancy waves in the surface inversion during the subarctic winter
Abstract
A microbarograph-array with low-frequency microphones was used to study buoyancy waves within the wintertime surface inversions at Kiruna, Sweden. The waves had characteristic periods of 1 to 1.5 minutes and a mean amplitude of 9 microbar. Wave velocities could be determined for a number of waves and a mean velocity of 8 m/s was found. Different types of inversions were compared with the buoyancy wave activity, and it was found that the wave activity was highest for strong inversions with small depths and with a sudden transition to an upper layer with near adiabatic lapse rate. These waves were also of better quality. No buoyancy wave activity was observed during days with inversions with a low temperature difference, which gradually changed to an upper layer. The winds at the top of the inversions had the highest speeds during good buoyancy wave activity. Periods with no buoyancy waves had a significantly lower wind speed. The mean wave velocity agreed with the mean wind speed aloft. Buoyancy wave activity was highest during winds from NNE and from W. These wind directions were found to be associated with strong inversions. Observations were found to agree with an atmospheric model with two layers and with wind and density discontinuities.
- Publication:
-
Unknown
- Pub Date:
- December 1975
- Bibcode:
- 1975bwsi.rept.....W
- Keywords:
-
- Acoustic Sounding;
- Gravity Waves;
- Subarctic Regions;
- Temperature Inversions;
- Winter;
- Atmospheric Models;
- Buoyancy;
- Earth Atmosphere;
- Meteorological Parameters;
- Microphones;
- Pressure Sensors;
- Sound Pressure;
- Surface Layers;
- Sweden;
- Wind Shear;
- Geophysics