Plume dispersion in the convective boundary layer. Part 2: Analyses of CONDORS field experiment data. [CONDORS (convective diffusion observed with remote sensors)]

Journal Article · Sun Aug 01 04:00:00 EDT 1993 · Journal of Applied Meteorology; (United States)

DOI:https://doi.org/10.1175/1520-0450(1993)032<1388:PDITCB>2.0.CO;2· OSTI ID:5824129

Briggs, G A ^[1]

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1. National Oceanic and Atmospheric Administration, Research Triangle Park, NC (United States)

Extensive analyses are performed on data from the CONDORS field experiment. Near-surface X/Q from lidar-detected oil fog are generally in excellent agreement with nearby samples of coreleased SF[sub 6], considering the large spatial gradients found in the oil fog. Extrapolations to the surface of [integral]xdy/Q of radar-detected [open quotes]chaff[close quotes] agree well with most oil fog values after a mathematical compensation for the chaff's settling speed. Measured wind direction distributions compared well with [integral] xdy and [integral] xdz distributions of both tracers. The directly measured bulk variables [sigma][sub y] and [sigma][sub z] show little effect of source height or of tracer type except that surface-released [sigma][sub y] are enhanced by up to 60% at X < 0.3 [X = (x/U)w[sub *]/z[sub i], where U is mean wind speed, w[sub *] is the convective scale velocity, and z[sub i] is mixing depth]. [sigma][sub y] [approx] 0.6z[sub i]X = 0.6w[sub *]x/U at X < 1, [sigma][sub y] [approx] 0.6z[sub i]X[sup 2/3] at X > 1, and [sigma][sub z] [approx] 0.6z[sub i]X until limited by reflections; [sigma][sub y] systematically reduces for averaging times divided by z[sub i]/U less than 6. For surface release at small X, oil fog surface-extrapolated [integral] xdy/Q had good agreement with Nieuwstadt; with Gaussian assumption, this implies [sigma][sub y] [approx] 0.9z[sub i]X[sup 3/2]. Composite patterns of C[sub y] = Uz[sub i] [integral] xdy/Q versus X and z/z[sub i] for surface releases are in agreement with Willis and Deardorff's laboratory and Lamb's LES simulations. In the aggregate, the oil and chaff measurements support a (1 + 2z[sub s]/z[sub i]) enhancement factor in maximum surface values of [integral] xdy over Gaussian plume model predictions, with maxima occurring near x = 2z[sub s]U/w[sub *], where z[sub s] is source height. Attention is focused on the effect of w anomalies and persistance of C[sub y] patterns. 41 refs., 26 figs., 3 tabs.

• OSTI ID: 5824129
• Journal Information: Journal of Applied Meteorology; (United States), Journal Name: Journal of Applied Meteorology; (United States) Vol. 32:8; ISSN 0894-8763; ISSN JOAMEZ
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
540120 -- Environment
Atmospheric-- Chemicals Monitoring &amp; Transport-- (1990-)
ATMOSPHERIC CIRCULATION
BOUNDARY LAYERS
CLIMATE MODELS
CONVECTION
DATA ANALYSIS
DIFFUSION
EARTH ATMOSPHERE
ENERGY TRANSFER
FLUID FLOW
HEAT TRANSFER
LAYERS
MASS TRANSFER
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
OPTICAL RADAR
PLUMES
RADAR
RANGE FINDERS
REMOTE SENSING
STRATIFICATION
WIND