Abstract
Abstract. New ozone (O3) profile climatologies are created from the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) O3 record between 2005 and 2016, within the period of Aura Microwave Limb Sounder (MLS) and Aura Ozone Monitoring Instrument (OMI) assimilation. These two climatologies consist of monthly mean O3 profiles and the corresponding covariances dependent on the local solar time, longitude (15∘), and latitude (10∘), which are parameterized by tropopause pressure and total O3 column. They are validated through comparisons, which show good agreements with previous O3 profile climatologies. Compared to a monthly zonal mean climatology, both tropopause- and column-dependent climatologies provide improved a priori information for profile and total O3 retrievals from remote sensing measurements. Furthermore, parameterization of the O3 profile with total column O3 usually reduces the natural variability of the resulting climatological profile in the upper stratosphere further than the tropopause parameterization, which usually performs better in the upper troposphere and lower stratosphere (UTLS). Therefore tropopause-dependent climatology is more appropriate for profile O3 retrieval for complementing the vertical resolution of backscattered ultraviolet (UV) spectra, while the column-dependent climatology is more suited for use in total O3 retrieval algorithms, with an advantage of complete profile specification without requiring ancillary information. Compared to previous column-dependent climatologies, the new MERRA-2 column-dependent climatology better captures the diurnal, seasonal, and spatial variations and dynamical changes in O3 profiles with higher resolutions in O3, latitude, longitude, and season. The new MERRA-2 climatologies contain the first quantitative characterization of O3 profile covariances, which facilitate a new approach to improve O3 profiles using the most probable patterns of profile adjustments represented by the empirical orthogonal functions (EOFs) of the covariance matrices. The MERRA-2 daytime column-dependent climatology is used in the combo O3 and SO2 algorithm for retrieval from the Earth Polychromatic Imaging Camera (EPIC) on board the Deep Space Climate Observatory (DSCOVR) satellite, the Ozone Mapping and Profiler Suite Nadir Mapper (OMPS-NM) on the Suomi National Polar Partnership (SNPP), and the Ozone Monitoring Instrument (OMI) on the Aura spacecraft.
Highlights
Remote sensing instruments measure spectral radiances, from which information about light absorbers such as ozone (O3) and other trace gases may be inferred using retrieval algorithms
The tropopause-pressure-dependent O3 profiles contained in the M2TPO3 climatology capture profile changes resulting from short-term meteorological disturbances in the upper troposphere and lower stratosphere (UTLS) region
The M2TCO3 climatology is constructed by binning the MERRA-2 O3 field at the same UTC time by total column in 25 DU steps, calendar month, and 15◦ × 10◦ longitude– latitude tiles
Summary
Remote sensing instruments measure spectral radiances, from which information about light absorbers such as ozone (O3) and other trace gases may be inferred using retrieval algorithms. For a band within the spectral range of significant atmospheric absorptions, its measured radiance is sensitive to the profiles, i.e., vertical distributions of light absorbers, and depends on other atmospheric state and surface variables. The retrieval of quantitative information about an absorber requires some knowledge of its vertical distribution. For retrieval of O3 from remote sensing measurements, the a priori knowledge is usually taken from an O3 profile climatology, which provides average O3 profiles and their variances. To improve a priori knowledge of O3 vertical distributions and its covariances and to address the deficiencies in existing O3 profile climatologies, we construct new O3 profile climatologies from the long-term global O3 field provided by a modern reanalysis system. We present comparisons to validate the new climatologies and summarize the present work in the last section
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