ИСТИНА

The problem of the mixing layer height (MLH) determination with the use of traditional sodar records is discussed. Unlike the most of well-known methods it is a new suggestion to determine separately two different mixing layer heights: “upper” MLH which indicates a top of an inversion inside wind shear layer (in which dynamical turbulence exists and creates echo-signal) and “lower” MLH which indicates as a rule unstable or weak-stable stratification below a bottom of elevated inversion. The experimental ozone profiling with fine resolution in the lower atmosphere confirms that two different MLH sometimes exist in the morning simultaneously one above another. According to this idea the diurnal courses of mixing layer heights - both “upper”, and “lower” - have been calculated on a base of long-term sodar observations at Moscow State University (MSU) for period from 1988 to 2003. Dynamics of both heights at various seasons is discussed. Some review information about different methods of the MLH sodar estimations in the past is presented.