Oscillation of wind temperature humidity in the atmospheric surface layer over tropical semi-arid stations

Analysis of wind, air temperature, humidity and rainfall data from Land Surface Processes Experiment (LASPEX) in the surface layer at Anand (22°35′N, 72°55′E) and Khandha (22°02′N, 73°11′E) during January to December 1997 is presented. Wind and temperature at various levels showed prominent diurnal variation. Progression of daily wind and temperature revealed the intra-seasonal, quasi-biweekly and 6–9 day oscillations indicated large-scale convection, transport of heat and water vapor from Arabian Sea towards these stations.Power spectrum of wind and humidity corroborated the planetary scale Madden–Julian oscillation in the surface layer. Periodic oscillations of 21, 6–9, 1 day and 12 h were prominent in the spectrum of all variables. Low-frequency spectral peaks showed the energy in wind is 2–3 times higher over Khandha than at Anand whereas temperature is 3 times higher at Anand than Khandha.