Impact of diurnal variability on UARS synoptic products

Fabrizio Sassi*, Murry Salby

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    2 Citations (Scopus)


    We examine the impact of diurnal variability on the synoptic behavior of ozone observed by the Upper Atmosphere Research Satellite (UARS). Synoptic products generated via Kalman filtering are compared against those recovered via Fast Fourier Synoptic Mapping (FFSM). In FFSM products, tracer anomalies defining distinct air masses that originate from different latitudes are approximately conserved. In Kalman products, the same anomalies and the accompanying air masses are diluted with their surroundings. The origin of these differences is traced to the different space-time spectrum inherent to the two synoptic products. In the spectrum of Kalman products, high zonal wavenumbers are exaggerated at low frequency relative to their counterparts in FFSM. This pathological behavior appears to result through aliasing from diurnal variability that is undersampled in the UARS observations. We discuss the relevance of these findings to subsequent analyses and to estimating momentum sources in the middle atmosphere.

    Original languageEnglish
    Pages (from-to)4349-4352
    Number of pages4
    JournalGeophysical Research Letters
    Issue number23
    Publication statusPublished - 1 Dec 1999


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