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| Titel |
Comparison of OMI UV observations with ground-based measurements at high northern latitudes |
| VerfasserIn |
G. Bernhard, A. Arola, A. Dahlback, V. Fioletov, A. Heikkilä, B. Johnsen, T. Koskela, K. Lakkala, T. Svendby, J. Tamminen |
| 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 ; 15, no. 13 ; Nr. 15, no. 13 (2015-07-09), S.7391-7412 |
| Datensatznummer |
250119877
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| Publikation (Nr.) |
 copernicus.org/acp-15-7391-2015.pdf |
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| Zusammenfassung |
| The Dutch–Finnish Ozone Monitoring Instrument (OMI) on board NASA's Aura
spacecraft provides estimates of erythemal (sunburning) ultraviolet (UV) dose
rates and erythemal daily doses. These data were compared with ground-based
measurements at 13 stations located throughout the Arctic and Scandinavia
from 60 to 83° N. The study corroborates results from earlier work,
but is based on a longer time series (8 versus 2 years) and considers
additional data products, such as the erythemal dose rate at the time of the
satellite overpass. Furthermore, systematic errors in satellite UV data
resulting from inaccuracies in the surface albedo climatology used in the OMI
UV algorithm are systematically assessed. At times when the surface albedo is
correctly known, OMI data typically exceed ground-based measurements by
0–11 %. When the OMI albedo climatology exceeds the actual albedo, OMI
data may be biased high by as much as 55 %. In turn, when the OMI albedo
climatology is too low, OMI data can be biased low by up to 59 %. Such
large negative biases may occur when reflections from snow and ice, which
increase downwelling UV irradiance, are misinterpreted as reflections from
clouds, which decrease the UV flux at the surface. Results suggest that a
better OMI albedo climatology would greatly improve the accuracy of OMI UV
data products even if year-to-year differences of the actual albedo cannot be
accounted for. A pathway for improving the OMI albedo climatology is
discussed. Results also demonstrate that ground-based measurements from the
center of Greenland, where high, homogenous surface albedo is observed year
round, are ideally suited to detect systematic problems or temporal drifts in
estimates of surface UV irradiance from space. |
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