Investigation of gravity waves in the atmospheric boundary layer using sodar and microbarograph

Abstract

Presence of irregularities and irregular motions in the atmospheric boundary layer (ABL) have been detected and studied by a variety of techniques, including sodars and microbarographs. The infrasonic pressure variations have been recorded at Tirupati using a microbarograph. Wave motions associated with temperature inversions in ABL are studied using an acoustic sounder and a microbarograph. Two-year investigation of waves and wave perturbations in low-level inversions in the atmosphere over Tirupati valley region are reported. A detailed study on wave motions in terms of diurnal variation, seasonal variation, occurrence percentage and amplitude of the wave motion associated with different structures in ABL is made. Simultaneous study of the nature of waves in the atmosphere is made using echosonde and microbarograph data. Gravity waves are mostly observed in this region during winter and premonsoon seasons due to temperature inversions and thunderstorms. In order to characterize the wave nature and to study the effect of their motions occurring mostly at nighttime stable conditions, cross-correlation and power spectral density technique have been applied.