Global distribution of C_T² at altitudes 30–50 km from space-borne observations of stellar scintillation

Alexandre S. Gurvich (1) , Viktoria F. Sofieva (2) , Francis Dalaudier (3)

1 IAP - A.M.Obukhov Institute of Atmospheric Physics
2 FMI - Finnish Meteorological Institute
3 SA - Service d'aéronomie

Locally isotropic turbulence in the stratosphere consists of isolated sporadic patches with random values of temperature structure characteristic C_T². Stellar scintillations measured aboard GOMOS/ENVISAT through the Earth atmosphere provided the first global distribution of the effective characteristic C² averaged along sounding ray. For zonal mean, the largest values are achieved in winter polar regions. This observed intense turbulence is probably related to the polar night jet. Relatively weak turbulence is observed at low latitudes. Turbulence intensity map is shown for altitude 42 km in the latitude band ±35°, where the maxima follow the sub-solar latitude, with enhancements located mainly over continents. Turbulence enhancements are not related with orography. Despite a noticeable correlation with typical regions of deep convection, the overall distribution of C_T,eft ² displays a more complicated structure. Analyzed data suggest that the main turbulence sources, at altitudes 〜40 km, are instabilities of stratospheric circulation and gravity wave breaking.

Mots clés: turbulence; stellar scintillation; GOMOS/Envisat

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

Alexandre S. Gurvich, Viktoria F. Sofieva, Francis Dalaudier. Global distribution of C_T² at altitudes 30–50 km from space-borne observations of stellar scintillation. Geophysical Research Letters, 2007, 34 (24), pp.L24813. ⟨10.1029/2007GL031134⟩. ⟨hal-00201348⟩