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| Titel |
NO2 climatology in the northern subtropical region: diurnal, seasonal and interannual variability |
| VerfasserIn |
M. Gil, M. Yela, L. N. Gunn, A. Richter, I. Alonso, M. P. Chipperfield, E. Cuevas, J. Iglesias, M. Navarro, O. Puentedura, S. Rodríguez |
| 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 ; 8, no. 6 ; Nr. 8, no. 6 (2008-03-18), S.1635-1648 |
| Datensatznummer |
250005929
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| Publikation (Nr.) |
 copernicus.org/acp-8-1635-2008.pdf |
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| Zusammenfassung |
| Daily NO2 vertical column density (VCD) has been routinely measured by
zenith sky spectroscopy at the subtropical station of Izaña (28° N,
16° W) since 1993 in the framework of the Network for the Detection of
Atmospheric Composition Change (NDACC). Based on 14 years of data the first
low latitude NO2 VCD climatology has been established and the main
characteristics from short timescales of one day to interannual variability
are presented. Instrumental descriptions and different sources of errors are
described in detail. The observed diurnal cycle follows that expected by
gas-phase NOx chemistry, as can be shown by the good agreement with a
vertically integrated chemical box model, and is modulated by solar
radiation. The seasonal evolution departs from the phase of the hours of
daylight, indicating the signature of upper stratospheric temperature
changes. From the data record (1993–2006) no significant long-term trends in
NO2 VCD can be inferred. Comparison of the ground-based data sets with
nadir-viewing satellite spectrometers shows excellent agreement for
SCIAMACHY with differences between both datasets of 1.1%. GOME displays
unrealistic features with the largest discrepancies during summer. The
ground-based data are compared with long-term output of the SLIMCAT 3-D
chemical transport model (CTM). The basic model, forced by ECMWF (ERA-40)
analyses, captures the observed NO2 annual cycle but significantly
underestimates the spring/summer maximum (by 12% at sunset and up to
25% at sunrise). In a model run which uses assimilation of satellite
CH4 profiles to constrain the model long-lived tracers the agreement is
significantly improved. This improvement in modelled column NO2 is due
to better modelled NOy profiles and points to transport errors in the ECMWF
ERA-40 reanalyses. |
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