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Time evolution of monsoon low-level jet observed over an Indian tropical station during the peak monsoon period from high-resolution Doppler wind lidar measurements

Ruchith, RD and Ernest Raj, P and Kalapureddy, MCR and Deshpande, SM and Dani, KK (2014) Time evolution of monsoon low-level jet observed over an Indian tropical station during the peak monsoon period from high-resolution Doppler wind lidar measurements. Journal of Geophysical Research: Atmospheres, 119 (4). pp. 1786-1795.

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Abstract

Doppler wind lidar measurements of horizontal winds at an Indian tropical station, Mahbubnagar (16.73°N, 77.98°E, 445-m above mean sea level), were used to investigate the time evolution of the monsoon low-level jet (MLLJ) during the southwest monsoon season. Vertical profiles of zonal wind in the altitude range of 100 to 3000-m above surface (at every 50-m height interval and 5-min time averaged) obtained during the period 25 July to 23 August 2011 are considered for the analysis. The zonal winds in the altitude up to 3000-m above ground are predominantly westerly throughout the period and on almost all the days there is a westerly wind speed maximum around 500-m above ground during nighttime. Soon after local sunrise, the core of this wind speed maximum (jet) gets lifted up and by afternoon, the westerly wind maximum is shifted to a higher altitude of 2000-m-2500-m without much change in its magnitude. Analysis of the high-resolution lidar data strongly indicates that the same nocturnal LLJ seems to be moving up and evolving into a daytime westerly MLLJ reported in several previous studies. Wind speed and direction derived from the wind lidar agree reasonably well with simultaneously observed GPS upper air sounding wind measurements. Further analysis shows that the time-height evolution of the jet core is closely associated with daytime convection and boundary layer growth. The presence of clouds over the region seems to inhibit this type of time evolution. Key Points Time evolution of monsoon low-level jet High-resolution measurements of winds in the boundary layer Doppler wind lidar measurements over tropical Indian location.

Item Type: Article
Additional Information: Copyright of this article belongs to American Geophysical Union.
Uncontrolled Keywords: Boundary layers; Optical radar; Sea level; Tropics; Wind, Boundary layer growth; Doppler wind lidar; High-resolution lidar; High-resolution measurements; Low level jet; Monsoon; Wind speed and directions; Zonal wind, Atmospheric thermodynamics, boundary layer; cloud cover; Doppler lidar; GPS; monsoon; vertical profile; westerly; wind profile; zonal wind, Andhra Pradesh; India; Mahabubnagar
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 04 Dec 2014 11:04
Last Modified: 04 Dec 2014 11:04
URI: http://moeseprints.incois.gov.in/id/eprint/916

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