Quantifying gravity waves and turbulence in the stratosphere using satellite stellar scintillation measurements
Abstract
Stellar scintillations observed through the Earth atmosphere are caused by air density irregularities generated mainly by internal gravity waves (GW) and turbulence. The strength of scintillation measurements is that they cover the transition between the saturated part of the gravity wave spectrum and isotropic turbulence. This allows visualization of gravity wave breaking and of resulting turbulence. In this presentation, we show global distributions and seasonal variations of the GW and turbulence spectra parameters retrieved from GOMOS data in 2003, for altitudes 30-50 km. In addition, we show global distributions of GW potential energy per unit mass and of turbulent structure characteristic CT2 . Since other measurements at such small scales are very scarce in this altitude range, the obtained global distributions provide unique and complementary information about small-scale air density irregularities. At altitudes and locations overlapping with other measurements, the GW and turbulence parameters retrieved from scintillations are in a good qualitative and quantitative agreement with that obtains from other measurements. Our main findings and observations are: (i) Strong enhancement of gravity wave activity at high latitudes in winter, accompanying with a strong turbulence appearing at altitudes above 40-45 km; indication on breaking of gravity waves in the polar night jet; (ii) The turbulent structure characteristic CT2 can reach values of 0.003 K2 m-2/3 in high- latitude winter stratosphere; these values are comparable with that in the boundary layer; (iii) Moderate turbulence enhancements in the tropics, located mainly over continents and related probably to tropical deep convection; (iv) Increase of GW outer scale in the equatorial region; (v) Exceptional gravity wave spectra and a very strong turbulence during sudden stratospheric warmings.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.A51A0084S
- Keywords:
-
- 3334 Middle atmosphere dynamics (0341;
- 0342);
- 3360 Remote sensing;
- 3379 Turbulence (4490)