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Titel |
Actinic flux and O1D photolysis frequencies retrieved from spectral measurements of irradiance at Thessaloniki, Greece |
VerfasserIn |
S. Kazadzis, C. Topaloglou, A. F. Bais, M. Blumthaler, D. Balis, A. Kazantzidis, B. Schallhart |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1680-7316
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Digitales Dokument |
URL |
Erschienen |
In: Atmospheric Chemistry and Physics ; 4, no. 8 ; Nr. 4, no. 8 (2004-11-18), S.2215-2226 |
Datensatznummer |
250002070
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Publikation (Nr.) |
copernicus.org/acp-4-2215-2004.pdf |
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Zusammenfassung |
The results of two methods retrieving actinic flux and ozone photolysis
frequencies (JO1D), from measurements of irradiance with a Brewer MKIII
spectroradiometer are investigated in this paper. The first method uses
actinic flux retrieved from irradiance measurements by the use of known
formulas while the second is an empirical method converting irradiance to
JO1D through polynomials extracted from a study of synchronous actinic
flux and irradiance measurements. When examining the actinic fluxes derived
from the first method to those measured by an actinic flux spectrometer data
agree within ±10% for solar zenith angles lower than 75° for
the UV-B and the UV-A wavelength band. Also, the actinic to global
irradiance ratio derived, deviates within ±6% for solar zenith
angles lower than 70° compared with cloudless sky calculations of the
TUV model. For both cases the deviations are in the order of the magnitude
of the measurement or model uncertainties. Values of JO1D calculated
by the second method show a mean ratio of 0.99±0.10 (1σ) and
0.98±0.06 for all data and for cloudless skies respectively when
compared with values of JO1D derived by a Bentham actinic flux
spectroradiometer. Finally, the agreement of the two methods is within
±5% comparing two years' data of JO1D retrieved from irradiance
measurements at Thessaloniki, Greece. The use of such methods on extensive
data sets of global irradiance can provide JO1D values with acceptable
uncertainty, a parameter of particular importance for chemical process
studies. |
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