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Abstract:
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The characteristics of the monsoon boundary layer are imperative to understand in the perception of the tropical
regions. The southwest monsoon is associated with a strong wind in the lower troposphere near 1.5 km and is referred to
as Low Level Jet stream (LLJ). The boundary layer structure associated with the LLJ during monsoon can be studied
using L-band Ultra High Frequency (UHF) radar. This L-band wind profiler-commonly referred as lower atmospheric
wind profiler (LAWP), was installed at NARL, Gadanki. Zonal, meridional and vertical wind components are used to
understand the diurnal variation of the wind in the Atmospheric Boundary Layer (ABL) and associated features. From the
analysis during non rainy days of the southwest monsoon, it is found that the LLJ has maximum strength during the early
morning hours at lower level and the height increases as day progresses. The vertical wind shows the transfer of momentum
from the LLJ towards the surface, indicating the sinking motion during the daytime. Vertical gradient of the wind shear
shows the intensity of clear air turbulence is moderate and no severe clear air turbulence is noticed during the monsoon
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