Development of the thermal internal boundary layer and spectral characteristics of turbulence in convective boundary layer over non-homogeneous terrain
Mikhail Strunin (1), Tesuya Hiyama (2), Jun Asanuma (3)
(1) 1) Central Aerological Observatory, Russia
(2) 2) Hydrospheric Atmospheric Research Center, Nagoya University, Japan
(3) 3) Terrestrial Environment Research Center, University of Tsukuba, Japan
Development of the thermal internal boundary layer (TIBL) was investigated based on the aircraft observations of convective boundary layer (CBL) in the frame of GAME-Siberia project in April -June of 2000.
TIBL in some flight days gave clear reflection to the vertical profiles of potential temperature and specific humidity measured from the aircraft and recorded by radiosondes. Another graphic demonstration of development of the TIBL was the fine structure of vertical sensible and vertical and horizontal latent heat fluxes. Observations on others flight days did not show existing of TIBL. Controlling parameters for appearing of the TIBL were the parameter of stability zi/L(zi was the depth of CBL and L was Obukhov's length) or special proposed parameter Ps, which was represented as the non-dimensional analog of the thermal blending height. It was shown that the TIBL was developed through the total depth of CBL only if there were simultaneously the strong non-stability in CBL with zi/L<-25 (or with parameter Ps<1) and surface strong thermal heterogeneity with the horizontal size more than 10 km and with temperature jump of 15 C. It was also shown that development of the TIBL was accompanied by alternation of the strong horizontal latent heat fluxes with opposite direction. This effect could be the reason of the differences between average latent heat fluxes observed over the left and right banks of Lena river.
Fourier and wavelet analyses were applied for studying the spectral structure of turbulence in CBL. Distributions of wavelet coefficients along with flight path demonstrated the steady-state situation at least for the lowest part of CBL. Influence of TIBL on the behavior of wavelet scalograms was shown.
Relations between behavior of the spectra of coherence and degree of stability zi/L, relative height z/zi(zi was the depth of CBL) and development of TIBL were shown. Correlation between the vertical wind speed fluctuations and air temperature became small for z/zi>0.6, but presence of the TIBL decreased values of the spectra already for z/zi~ 0.3.
Submittal Information
Name :
Date :
Mikhail Strunin
30-May-01-03:44:15
Organization :
Theme :
Central Aerological Observatory
Theme 2
Address :
Presentation :
3, Pervomayskaya, Dolgoprudny, Moscow Region, 141700, Russia
