Multi-Sensor Observations of the Nocturnal Boundary Layer:
Preliminary Analyses
Justin Walters+ and Kevin Knupp
Department of Atmospheric Science
University of Alabama in Huntsville
Huntsville, AL 35899
A multi-sensor atmospheric boundary layer (ABL) measurement facility has recently been established from new and existing equipment under DoD and UAH ownership. This is an operational facility capable of acquiring detailed four-dimensional ABL measurements. The primary components include the following: (a) the Mobile Integrated Profiling System (MIPS), consisting of a five-beam 915 MHz profiler radar, a three-beam 2 kHz sodar and a 0.905 mm laser ceilometer (Vaisala CT-25K), (b) a dual Doppler (S- and C-band) radar network with a 13 km baseline; (c) fixed and mobile rawinsonde units; (d) an instrumented 30 m tower; and (e) a meso-g network of 18 surface meteorological stations. The sodar and radar operate together to also provide a Radio Acoustic Sounding System for measurements of virtual temperature. This integrated cluster of instrumentation will measure detailed ABL flows and thermodynamics over a 100-200 km2 region of Redstone Arsenal and adjacent regions. Surface characteristics over this region are distinctly heterogeneous, and consist of wetlands, significantly variable topography, forests and agricultural stands. With this facility, we plan to develop a climatology of the NBL and investigate the detailed structure of the NBL through comprehensive case studies and associated numerical modeling activities.
This paper will present preliminary measurements of the nocturnal boundary layer (NBL), including the temporal and spatial variability of the NBL. We will focus on documentation of the NBL breakdown process and attempt to relate transient breakdowns to various physical processes. These include topographic/surface influences (as determined from single/dual Doppler radar analyses), changes in the surface radiative balance (e.g., from advection of water vapor and clouds, as measured by the ceilometer), and gravity waves (as determined from vertical velocity measurements from the 915 MHz profiler and sodar)