 |
| Titel |
Ultrafine sea spray aerosol over the southeastern Pacific: open-ocean contributions to marine boundary layer CCN |
| VerfasserIn |
R. Blot, A. D. Clarke, S. Freitag, V. Kapustin, S. G. Howell, J. B. Jensen, L. M. Shank, C. S. McNaughton, V. Brekhovskikh |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 14 ; Nr. 13, no. 14 (2013-07-30), S.7263-7278 |
| Datensatznummer |
250018791
|
| Publikation (Nr.) |
 copernicus.org/acp-13-7263-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| Accurate measurements of natural aerosol emissions over the ocean
are needed to estimate the anthropogenic impact on the
environment. In this study, we measured sea spray aerosol (SSA)
concentrations with diameters larger than 0.040 μm
produced by open-ocean breaking waves over the SEP (southeastern
Pacific). Robust statistics were established through repeated
airborne flights over 1000 km along 20° S from the
coastline of Chile to 85° W during VOCALS-REx (VAMOS
Ocean-Cloud-Atmosphere-Land-Study Regional Experiment). Non-volatile
SSA number concentrations were inferred using a thermally resolved
technique constrained for clean conditions with an Ångström
exponent below 0.5, black carbon mass concentration at values
lower than 15 ng m−3 and organic aerosol
concentration less than 0.02 μg m−3. We found that
number concentrations of SSAs active as cloud condensation nuclei (CCN) for a supersaturation of
0.25% varied between 17 and 36 cm−3,
but these did not increase with the increasing mean wind speed
typically observed further offshore along 20° S. Concurrent
increases in mean offshore precipitation rate in excess of about
1 mm d−1 indicate that scavenging of SSAs by precipitation
exceeds increases in production at wind speeds above about
8 m s−1. This demonstrates the critical role of
precipitation as a major sink of SSA over the remote ocean. Finally,
we found that under clean conditions and for estimated stratus
supersaturations between 0.20 and 0.43%, SSA represented
about 20% of the total potential CCN along 20° S. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|