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| Titel |
The effect of hygroscopicity on eddy covariance estimates of sea-spray aerosol fluxes: a comparison of high-rate and bulk correction methods |
| VerfasserIn |
D. A. J. Sproson, I. M. Brooks, S. J. Norris |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 6, no. 2 ; Nr. 6, no. 2 (2013-02-13), S.323-335 |
| Datensatznummer |
250017392
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| Publikation (Nr.) |
 copernicus.org/amt-6-323-2013.pdf |
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| Zusammenfassung |
The eddy covariance technique is the most direct of the methods that have
been used to measure the flux of sea-spray aerosol between the ocean and
atmosphere, but has been applied in only a handful of studies. However,
unless the aerosol is dried before the eddy covariance measurements are made,
the hygroscopic nature of sea-spray may combine with a relative humidity flux
to result in a bias in the calculated aerosol flux. "Bulk" methods have
been presented to account for this bias, however, they rely on assumptions of
the shape of the aerosol spectra which may not be valid for near-surface
measurements of sea-spray.
Here we describe a method of correcting aerosol spectra for relative humidity
induced size variations at the high frequency (10 Hz) measurement timescale,
where counting statistics are poor and the spectral shape cannot be well
represented by a simple power law. Such a correction allows the effects of
hygroscopicity and relative humidity flux on the aerosol flux to be
explicitly evaluated and compared to the bulk corrections, both in their
original form and once reformulated to better represent the measured mean
aerosol spectra. In general, the bulk corrections – particularly when
reformulated for the measured mean aerosol spectra – perform relatively
well, producing flux corrections of the right sign and approximate magnitude.
However, there are times when the bulk methods either significantly over- or
underestimate the required flux correction. We conclude that, where
possible, relative humidity corrections should be made at the measurement
frequency. |
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