Some atmospheric surface layer characteristics over Varanasi from MONTBLEX-90

An attempt has been made to study the atmospheric surface layer characteris tics such as Richardson number (Ri). Monin-Obukhov length scale (L), fricti on velocity (U-*), friction temperature (theta(*)), roughness length (Z(0)) , turbulent kinetic energy (TKE), ratio of eddy conductivity to eddy diffus ivity (K-m/K-h) over a semi-moist convective regime. Data which were collec ted at Varanasi (25 degrees 18'N, 83 degrees E) as part of the experiment k nown as MONTBLEX-90 (Monsoon Trough Boundary Layer Experiment) during the s ummer monsoon season was used in the present study. The variation of the ab ove parameters with stability has been discussed. The differences within th e surface layer are also pointed out. Some broad features are found to coin cide with that of BUSINGER ct al. (1971). The heterogeneity and the anisotr opic turbulence typical of monsoon tropical atmosphere are shown to be resp onsible for the deviations noticed within the surface layer.