I.: Measurements of gravity wave activity within and around the Arctic stratospheric vortex, Geophys. Res
Abstract. Lidar measurements of gravity wave activity have been conducted at Eureka in the High Arctic since 1993. The waves are detected by the fluctuations they induce in temperature. It has been found that the amount of wave energy in the upper stratosphere is related to the position of the strat...
| Main Authors: | , , , , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.564.4922 http://aolab.phys.dal.ca/publications/grl1997a.pdf |
| Summary: | Abstract. Lidar measurements of gravity wave activity have been conducted at Eureka in the High Arctic since 1993. The waves are detected by the fluctuations they induce in temperature. It has been found that the amount of wave energy in the upper stratosphere is related to the position of the stratospheric polar vortex. In each of the four winters reported here, the wave activity was a maximum within the westerly jet at the edge of the vortex, a minimum inside the vortex near its centre and intermediate outside the vortex. The spectra of wave induced fluctuations how that it is at the longest resolved vertical wavelengths (8 to 15 km) that wave energy is being influenced by the background meteorological conditions. These findings are interpreted in terms of the Doppler shifting and critical level filtering that is imposed by the background wind profile. Within the westerly jet the wind speed increases with height and its direction does not change substantially. We have been able to observe how the gravity wave activity changed in response to these distinct changes in the background dynamical conditions. Observations The lidar at Eureka is able to measure profiles of temperature within the upper stratosphere and lower mesosphere. (Details of the measurement and analysis technique are described elsewhere [Whiteway and Carswell 1994, 1995].) The vertical resolution in the measurement is 300 m and for gravity wave studies we use half hour average profiles. Figure 2a shows a half hour average temperature profile that has been smoothed in the vertical with a |
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