 |
| Titel |
The part of the solar spectrum with the highest influence on the formation of SOA in the continental boundary layer |
| VerfasserIn |
M. Boy, M. Kulmala  |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 2, no. 5 ; Nr. 2, no. 5 (2002-11-28), S.375-386 |
| Datensatznummer |
250000657
|
| Publikation (Nr.) |
 copernicus.org/acp-2-375-2002.pdf |
|
|
|
|
|
| Zusammenfassung |
| The relationship between nucleation events and spectral solar irradiance was
analysed using two years of data collected at the Station for Measuring Forest
Ecosystem-Atmosphere Relations (SMEAR II) in Hyytiälä, Finland. We analysed the
data in two different ways. In the first step we calculated ten nanometer average
values from the irradiance measurements between 280 and 580 nm and explored if
any special wavelengths groups showed higher values on event days compared to a
spectral reference curve for all the days for 2 years or to reference curves for every
month. The results indicated that short wavelength irradiance between 300 and
340 nm is higher on event days in winter (February and March) compared to the monthly
reference graph but quantitative much smaller than in spring or summer. By building
the ratio between the average values of different event classes and the yearly
reference graph we obtained peaks between 1.17 and 1.6 in the short wavelength
range (300--340 nm). In the next step we included number concentrations of particles
between 3 and 10 nm and calculated correlation coefficients between the different
wavelengths groups and the particles. The results were quite similar to those
obtained previously; the highest correlation coefficients were reached for the spectral
irradiance groups 3--5 (300--330 nm) with average values for the single event classes
around 0.6 and a nearly linear decrease towards higher wavelengths groups by
30%. Both analyses indicate quite clearly that short wavelength irradiance between 300
and 330 or 340 nm is the most important solar spectral radiation for the formation of
newly formed aerosols. In the end we introduce a photochemical mechanism as one
possible pathway how short wavelength irradiance can influence the formation of SOA
by calculating the production rate of excited oxygen. This mechanism shows in which
way short wavelength irradiance can influence the formation of new particles even
though the absolute values are one to two magnitudes smaller compared to irradiance
between 400 and 500 nm. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|