Show simple item record

The ASSET intercomparison of ozone analyses: Method and first results

dc.contributor.authorGeer, A.J.
dc.contributor.authorLahoz, W.A.
dc.contributor.authorBekki, S.
dc.contributor.authorBormann, N.
dc.contributor.authorErrera, Q.
dc.contributor.authorEskes, H.J.
dc.contributor.authorFonteyn, D.
dc.contributor.authorJackson, D.R.
dc.contributor.authorJuckes, M.N.
dc.contributor.authorMassart, S.
dc.contributor.authorPeuch, V.-H.
dc.contributor.authorRharmili, S.
dc.contributor.authorSegers, A.
dc.date2006
dc.date.accessioned2016-11-21T14:18:46Z
dc.date.available2016-11-21T14:18:46Z
dc.identifier.urihttps://orfeo.belnet.be/handle/internal/4485
dc.descriptionThis paper aims to summarise the current performance of ozone data assimilation (DA) systems, to show where they can be improved, and to quantify their errors. It examines 11 sets of ozone analyses from 7 different DA systems. Two are numerical weather prediction (NWP) systems based on general circulation models (GCMs); the other five use chemistry transport models (CTMs). The systems examined contain either linearised or detailed ozone chemistry, or no chemistry at all. In most analyses, MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) ozone data are assimilated; two assimilate SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) observations instead. Analyses are compared to independent ozone observations covering the troposphere, stratosphere and lower mesosphere during the period July to November 2003. Biases and standard deviations are largest, and show the largest divergence between systems, in the troposphere, in the upper-troposphere/lower-stratosphere, in the upperstratosphere and mesosphere, and the Antarctic ozone hole region. However, in any particular area, apart from the troposphere, at least one system can be found that agrees well with independent data. In general, none of the differences can be linked to the assimilation technique (Kalman filter, three or four dimensional variational methods, direct inversion) or the system (CTM or NWP system). Where results diverge, a main explanation is the way ozone is modelled. It is important to correctly model transport at the tropical tropopause, to avoid positive biases and excessive structure in the ozone field. In the southern hemisphere ozone hole, only the analyses which correctly model heterogeneous ozone depletion are able to reproduce the near-complete ozone destruction over the pole. In the upper-stratosphere and mesosphere (above 5 hPa), some ozone photochemistry schemes caused large but easily remedied biases. The diurnal cycle of ozone in the mesosphere is not captured, except by the one system that includes a detailed treatment of mesospheric chemistry. These results indicate that when good observations are available for assimilation, the first priority for improving ozone DA systems is to improve the models. The analyses benefit strongly from the good quality of the MIPAS ozone observations. Using the analyses as a transfer standard, it is seen that MIPAS is ∼5% higher than HALOE (Halogen Occultation Experiment) in the mid and upper stratosphere and mesosphere (above 30hPa), and of order 10% higher than ozonesonde and HALOE in the lower stratosphere (100hPa to 30hPa). Analyses based on SCIAMACHY total column are almost as good as the MIPAS analyses; analyses based on SCIAMACHY limb profiles are worse in some areas, due to problems in the SCIAMACHY retrievals.
dc.languageeng
dc.titleThe ASSET intercomparison of ozone analyses: Method and first results
dc.typeArticle
dc.subject.frascatiEarth and related Environmental sciences
dc.audienceScientific
dc.subject.freeatmospheric modeling
dc.subject.freeatmospheric transport
dc.subject.freeatomic absorption spectroscopy
dc.subject.freedata assimilation
dc.subject.freeerror analysis
dc.subject.freegeneral circulation model
dc.subject.freeinterferometer
dc.subject.freeKalman filter
dc.subject.freemesosphere
dc.subject.freeozone
dc.subject.freeozone depletion
dc.subject.freeozonesonde
dc.subject.freeperformance assessment
dc.subject.freestratosphere
dc.subject.freetroposphere
dc.source.titleAtmospheric Chemistry and Physics
dc.source.volume6
dc.source.issue12
dc.source.page5445-5474
Orfeo.peerreviewedYes
dc.identifier.doi10.5194/acp-6-5445-2006
dc.identifier.scopus2-s2.0-33749174946


Files in this item

Thumbnail
Name:
Geer(2006).pdf
Size:
3.126Mb
Format:
PDF
View/Open

This item appears in the following Collection(s)

Show simple item record