Intercomparison of Nocturnal Lower-Atmospheric Structure Observed with Lidar and Sodar Techniques at Pune, India

Abstract

Coordinated experiments to study the nocturnal lower atmosphere were conducted on selected nights during April?August 1991 using an argon ion lidar and a Doppler sodar at the Indian Institute of Tropical Meteorology, Pune (18°32?N, 73°51?E, 559 m MSL), India. The lidar and the sodar have been operated simultaneously so as to detect the nocturnal atmospheric structure in the common air volume sampled by both the techniques. By analyzing the thermal and aerosol structures in the vertical profiles of the sodar and the lidar signal intensity, the nocturnal mixed-layer height or ground-based inversion height and the stably stratified or multiple elevated layers aloft have been determined. The top of the nocturnal ground-based inversion observed in the sodar records is taken as the height above the ground where the negative vertical gradient in aerosol concentration first reaches a maximum in the lidar records. The results of the study indicate an agreement between the lidar-derived mixing depth and the sodar-derived heights of the ground-based inversion and the low-level wind maximum.