Investigation of wind shear structure and turbulence characteristics in a warm front cloud system using a research aircraft

Abstract

The manuscript presents the results of study vertical and horizontal wind shears, the spectral characteristics of turbulence in the warm front cloud system with using the Yak-42D aircraft-laboratory. Within the As-Cs clouds at altitudes of 3 - 8 km, vertical wind shear increased sharply to 1.5 ms-1 per 100 m. At altitudes of 8 - 9 km, in the jet stream zone, vertical wind shear increased up to significant values of 3.0 ms-1 per 100 m. The maximum horizontal wind shear of 0.3 ms-1 per km was reached in As-Ns clouds at altitudes of 2 - 4 km. Anisotropy of turbulence with a predominance of horizontal wind fluctuations was observed in the stable layer at the altitude of 6000 m. The normalized spectra of the wind speed fluctuations in the lower part of the cloud system (at an altitude of about 3 km) corresponded to the stable layers of the atmosphere. The maximum value of 0.8 at the coherence spectra between the temperature and the vertical wind speed fluctuations was observed at the scales of 1200 m. It is noted that a solid Cs-As-Ns cloud system could be divided into sub-layers, depending on structure of wind shear and turbulence.