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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

dc.contributor.authorBoersma, K.F.
dc.contributor.authorJacob, D.J.
dc.contributor.authorTrainic, M.
dc.contributor.authorRudich, Y.
dc.contributor.authorDe Smedt, I.
dc.contributor.authorDirksen, R.
dc.contributor.authorEskes, H.J.
dc.date2009
dc.date.accessioned2016-04-05T11:22:55Z
dc.date.available2016-04-05T11:22:55Z
dc.identifier.urihttps://orfeo.belnet.be/handle/internal/3264
dc.descriptionWe 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 froma 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.
dc.languageeng
dc.titleValidation 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
dc.typeArticle
dc.subject.frascatiEarth and related Environmental sciences
dc.audienceScientific
dc.subject.freeatmospheric chemistry
dc.subject.freeboundary layer
dc.subject.freeconcentration (composition)
dc.subject.freediurnal variation
dc.subject.freeEnvisat-1
dc.subject.freein situ measurement
dc.subject.freenitrogen dioxide
dc.subject.freenitrogen oxides
dc.subject.freenumerical model
dc.subject.freephotochemistry
dc.subject.freeSCIAMACHY
dc.subject.freeseasonal variation
dc.subject.freethree-dimensional modeling
dc.subject.freetroposphere
dc.subject.freeurban atmosphere
dc.subject.freeCairo [Egypt]
dc.subject.freeEgypt
dc.subject.freeIsrael
dc.source.titleAtmospheric Chemistry and Physics
dc.source.volume9
dc.source.issue12
dc.source.page3867-3879
Orfeo.peerreviewedYes
dc.identifier.scopus2-s2.0-73949124016


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