Evolution of the vertical profile and flux of large sea-salt particles in a coastal zone
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Authors
Reid, Jeffrey S.
Jonsson, Haflidi H.
Smith, Michael H.
Smirnov, Alexander
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2001
Date
2001
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Abstract
In the vicinity of the North Carolina Outer Banks we observed both steady
onshore flow conditions and a continental air mass transition into a marine boundary
layer. Using the CIRPAS Twin Otter aircraft, we measuredc hangesin the columnb urden
of sea salt as the air mass was advected out to sea. We also measured the flux of
whitecap-generatesde a-saltp articlesi n neutrallys tablea tmospherea t wind speedso f 4, 8,
and1 2r n s- •. Productioonf saltp articleass s malla s0 .27/•mi n diametewr aso bserved.
Furthermore,w e measureds alt particle size distributionsa t variousw ind speedsd uring
alongs horew ind and near steadys tate conditionsU. sing thesem easurementsa s a frame
of reference,w e discussth e very large differencesi n the reported size and flux of sea salt
presentedi n the literature. The disagreemenitn reported salt fluxesi s larger for smallersizedp
articles( almosta n order of magnitude)a nd is most likely due to assumptionms ade
when the fluxesw ere computed,e speciallyt he particle dry depositionv elocitya nd air mass
history.H owever,f or giant salt particlesw ith short atmosphericli fetimes (>-10/•m in
diameter),t here is generala greementb etweenf luxesa nd size distributionsm easuredi n
this studya nd previouso nes.R eported salt particle size distributionsin the literature also
vary considerablyu nder similar steadyw ind and stability conditions.F rom these and our
results it is clear that no more than half of the variance in salt particle concentration can
be explainedb y wind speeda lone, suggestingth at the idea of "steadys tate" in the marine
boundary layer rarely exists at midlatitudes.
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Journal of Geophysical Research, Vol. 106, No. D11, pp. 12,039 - 12,053, June 16, 2001.
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Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS)
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.