 |
| Titel |
Validation of urban NO2 concentrations and their diurnal and seasonal variations observed from the SCIAMACHY and OMI sensors using in situ surface measurements in Israeli cities |
| VerfasserIn |
K. F. Boersma, D. J. Jacob, M. Trainic, Y. Rudich, I. DeSmedt, R. Dirksen, H. J. Eskes |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 12 ; Nr. 9, no. 12 (2009-06-15), S.3867-3879 |
| Datensatznummer |
250007423
|
| Publikation (Nr.) |
 copernicus.org/acp-9-3867-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| We compare a full-year (2006) record of surface air NO2 concentrations
measured in Israeli cities to coinciding retrievals of tropospheric NO2
columns from satellite sensors (SCIAMACHY aboard ENVISAT and OMI aboard
Aura). This provides a large statistical data set for validation of NO2
satellite measurements in urban air, where validation is difficult yet
crucial for using these measurements to infer NOx emissions by
inverse modeling. Assuming that NO2 is well-mixed throughout the boundary
layer (BL), and using observed average seasonal boundary layer heights,
near-surface NO2 concentrations are converted into BL NO2 columns. The
agreement between OMI and (13:45) BL NO2 columns (slope=0.93, n=542),
and the comparable results at 10:00 h for SCIAMACHY, allow a validation of
the seasonal, weekly, and diurnal cycles in satellite-derived NO2. OMI and
BL NO2 columns show consistent seasonal cycles (winter NO2
1.6–2.7× higher than summer). BL and coinciding OMI columns both show
a strong weekly cycle with 45–50% smaller NO2 columns on Saturday
relative to the weekday mean, reflecting the reduced weekend activity, and
validating the weekly cycle observed from space. The diurnal difference
between SCIAMACHY (10:00) and OMI (13:45) NO2 is maximum in summer when
SCIAMACHY is up to 40% higher than OMI, and minimum in winter when OMI
slightly exceeds SCIAMACHY. A similar seasonal variation in the diurnal
difference is found in the source region of Cairo. The surface measurements
in Israel cities confirm this seasonal variation in the diurnal cycle. Using
simulations from a global 3-D chemical transport model (GEOS-Chem), we show
that this seasonal cycle can be explained by a much stronger photochemical
loss of NO2 in summer than in winter. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|