STATISTICS OF AIR-TEMPERATURE SPATIAL VARIABILITY IN THE ATMOSPHERIC SURFACE-LAYER

Surface-layer convection is investigated by analyzing multi-point meas urements of temperature and velocity fluctuations at different sets of spatial points. The visual analysis of temperature and velocity fluct uations measured by sensors mounted on a mast of 36-m height clearly r eveals the presence of large-scale convective cells (known as ramp str uctures) making large contributions to the heat transfer from the grou nd to lower atmosphere. The vertical temperature variability is descri bed with the aid of empirical orthogonal functions derived from temper ature covariance matrices for the heights of 1, 2, 5, 10, 18 and 36 m. Temporal-spatial correlation functions obtained allow estimates of a characteristic velocity scale, which may be interpreted as the downwin d velocity of ramp structures.