Dual tracer measurements of plume depletion

Conference · Fri Oct 01 04:00:00 EDT 1982

OSTI ID:6566347

Horst, T W; Doran, J C; Nickola, P W

Although many models are available for simulating the depletion of a diffusing plume by dry deposition, little data are available to evaluate these models. This is partly due to the difficulty of measuring small deposition losses with enough accuracy throughout the plume to evaluate a mass budget and determine the appropriate deposition velocity. This paper proposes a new method for determining the deposition velocity that requires only near-surface sampling. Three techniques were evaluated for determining the deposition velocity from the depletion of an airborne plume. These are the mass budget, depletion budget, and surface depletion methods. The mass budget is a straight-forward technique but it requires extensive sampling to define the elevated portion of the plume. These elevated samplers must be closely spaced in the crosswind direction to accurately measure the decrease in downwind mass flux that defines the loss as a function of downwind distance. The height to which these measurements must be made can be reduced, particularly for elevated sources, by the use of a second, non-depositing tracer and the depletion budget approach. However the crosswind spacing requirements are unchanged. The surface depletion method is based on less straight-forward, but physically realistic, assumptions and also requires the use of both depositing and non-depositing tracers, but it eliminates entirely the need for elevated sampling. This is a major advantage since dense surface sampling is much easier to implement than elevated sampling. For a polydisperse depositing tracer, these plume depletion techniques give an effective deposition velocity averaged between the source and receptor. In many cases this is the appropriate deposition velocity for use in a monodisperse simulation of the observations.

• Research Organization: Pacific Northwest Lab., Richland, WA (USA)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6566347
• Report Number(s): PNL-SA-10416; CONF-821136-17; ON: DE83005551
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION
COMPARATIVE EVALUATIONS
DEPOSITION
DIFFUSION
ENVIRONMENTAL TRANSPORT
ISOTOPE APPLICATIONS
MASS TRANSFER
MATHEMATICAL MODELS
METEOROLOGY
PLUMES
POLLUTION
SAMPLING
SURFACES
TRACER TECHNIQUES
VELOCITY
WIND