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| Titel |
MAX-DOAS formaldehyde slant column measurements during CINDI: intercomparison and analysis improvement |
| VerfasserIn |
G. Pinardi, M. Roozendael, N. Abuhassan, C. Adams, A. Cede, K. Clémer, C. Fayt, U. Frieß, M. Gil, J. Herman, C. Hermans, F. Hendrick, H. Irie, A. Merlaud, M. Navarro Comas, E. Peters, A. J. M. Piters, O. Puentedura, A. Richter, A. Schönhardt, R. Shaiganfar, E. Spinei, K. Strong, H. Takashima, M. Vrekoussis, T. Wagner, F. Wittrock, S. Yilmaz |
| 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. 1 ; Nr. 6, no. 1 (2013-01-31), S.167-185 |
| Datensatznummer |
250017379
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| Publikation (Nr.) |
 copernicus.org/amt-6-167-2013.pdf |
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| Zusammenfassung |
| We present intercomparison results for formaldehyde (HCHO) slant column
measurements performed during the Cabauw Intercomparison campaign of
Nitrogen Dioxide measuring Instruments (CINDI) that took place in Cabauw,
the Netherlands, in summer 2009. During two months, nine atmospheric
research groups simultaneously operated MAX-DOAS (MultiAXis Differential Optical Absorption Spectroscopy) instruments of various
designs to record UV-visible spectra of scattered sunlight at different
elevation angles that were analysed using common retrieval settings. The
resulting HCHO data set was found to be highly consistent, the mean
difference between instruments generally not exceeding 15% or
7.5 × 1015 molec cm−2, for all viewing elevation angles. Furthermore,
a sensitivity analysis was performed to investigate the uncertainties in the
HCHO slant column retrieval when varying key input parameters such as the
molecular absorption cross sections, correction terms for the Ring effect or
the width and position of the fitting interval. This study led to the
identification of potentially important sources of errors associated with
cross-correlation effects involving the Ring effect, O4, HCHO and BrO
cross sections and the DOAS closure polynomial. As a result, a set of
updated recommendations was formulated for HCHO slant column retrieval in
the 336.5–359 nm wavelength range. To conclude, an error budget is proposed
which distinguishes between systematic and random uncertainties. The total
systematic error is estimated to be of the order of 20% and is dominated
by uncertainties in absorption cross sections and related spectral
cross-correlation effects. For a typical integration time of one minute,
random uncertainties range between 5 and 30%, depending on the noise
level of individual instruments. |
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