> Laboratory Highlight: ARL Collaborates in Planetary Boundary Layer Study
ARL
Collaborates in Planetary Boundary
Layer Study
Air Resources Laboratory (ARL) scientists are collaborating with
researchers from NOAA's National Centers for Environmental Prediction
(NCEP) on an investigation of the evolution of the urban daytime
planetary boundary layer (PBL). The PBL is the mixed layer of the
atmosphere closest to the ground that is influenced by many factors,
including local topographical features, surface heating, surface type,
large-scale weather patterns, and cloud cover. The study will run
September 14-22. ARL's contribution to the study involves using the
existing surface turbulence measurements offered by ARL's DCNet system
and deploying two portable rawinsonde upper air measurement systems at
two of the DCNet locations: Howard University and RFK stadium. The goal
of this study is to develop an urban meteorological evaluation database
to investigate the daytime evolution and spatial variability of the
urban atmospheric boundary layer mixing height. ARL's measurements will
join other measurements conducted by scientists at Howard University
and the University of Maryland Baltimore. NCEP will provide mixing
height estimates from the Aircraft Communications Addressing and Report
System (ACARS) profiles, the Cloud-Aerosol Lidar and Infrared
Pathfinder Satellite Observations (CALIPSO), and the Constellation
Observing System for Meteorology, Ionosphere and Climate (COSMIC)
satellites. NCEP also will model predicted boundary layer heights from
the Rapid Update Cycle (RUC).
Background: The mixed layer height
is a key atmospheric parameter for all models intended to predict
conditions at the surface, and especially for atmospheric dispersion
and air quality models since the PBL height controls the depth of the
atmosphere over which emissions will be diluted. Mixed layer heights
exhibit strong diurnal patterns, and the development of the layer is
influenced by many factors. It is also generally accepted by the
atmospheric science community that the mixed layer depth over urban
environments is significantly enhanced from additional surface heating
generated from the urban canopy. Although urban regimes have been the
focus of considerable research, the evolution of the urban PBL remains
somewhat obscure. This study will explore the feasibility of
characterizing the temporal and spatial development of the daytime
mixed layer height using various remote sensing capabilities.
Significance: A large proportion of the U.S. population lives within
or near an urban environment. Accurate assessment of the dynamics of
the PBL at finer scales will improve the Nation's ability to assess the
effects of a toxic or hazardous materials release should one occur.
This project also supports the demonstration of NOAA's Real-Time
Mesoscale Analysis of PBL information for use by plume dispersion
modelers.
ARL
Collaborates in Planetary Boundary
Layer Study
