A long‐term stratospheric ozone data set from assimilation of satellite observations: High‐latitude ozone anomalies

Abstract

[1] A 29 year data set of stratospheric ozone from sequential assimilation of solar backscatter UV (SBUV) satellite ozone profile observations into a chemical transport model is introduced and validated against independent observations (satellite instruments and sondes). Our assimilated data set shows excellent agreement with ozone profile data from sonde measurements from high-latitude observation sites on both hemispheres and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) satellite observations, including during polar night when no SBUV observations are available. Although we only assimilate ozone profiles, total column ozone in the assimilated data set is in good agreement with independent satellite observations from the Global Ozone Monitoring Experiment (GOME), the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY), and the Total Ozone Mapping Spectrometer (TOMS). The data set can thus be viewed as a consistent long-term data set closing the gaps in satellite observations in order to investigate high-latitude ozone variability. We then use the assimilated data set to analyze the development and persistence of both high and low ozone anomalies in the Arctic stratosphere. Ozone anomalies typically develop in the 1000 K potential temperature (∼35 km) region and slowly descend from there, remaining visible for around 7 months. Anomalies in the stratospheric circulation, expressed by the Northern Hemisphere annular mode (NAM) index, show a large influence on ozone anomalies. Extreme phases of the NAM index (strong and weak vortex events) lead to the creation of distinctively shaped ozone anomalies, which first appear in the uppermost stratosphere and then rapidly cover the upper and middle stratosphere, from where they then slowly descend into the lowermost stratosphere within 5 months.Citation: Kiesewetter, G., B.-M. Sinnhuber, M. Vountas, M. Weber, and J. P. Burrows (2010), A long-term stratospheric ozone data set from assimilation of satellite observations: High-latitude ozone anomalies,

Attribution of stratospheric ozone trends to chemistry and transport: a modelling study

“…We use a time-dependent version of the linearized ozone chemistry ("Linoz v2") described by Hsu and Prather (2009), an update to the Linoz scheme introduced by McLinden et al (2000) which has been used in our CTM before (Kiesewetter et al, 2010). Although this chemistry scheme is simple, using only one ozone tracer and net production rates parameterized according to ozone volume mixing ratio (O 3 ), temperature (T ), and ozone column above the respective grid cell (CO3), it has been shown to generate realistic ozone fields (Hsu and Prather, 2009).…”

Temperature thresholds for chlorine activation and ozone loss in the polar stratosphere

“…Although it has been stated for more than a decade that polar chlorine activation is caused to a large extent by heterogeneous reactions on liquid-phase particles (e.g., Solomon, 1999), T NAT (or, alternatively, 195 K) is still being used as a first-order approximation to parameterise the onset of heterogeneous chlorine activation in models (Geer et al, 2006;Kiesewetter et al, 2010;Eyring et al, 2010;Morgenstern et al, 2010). Furthermore, measurements have shown that the total volume of air exposed to temperatures below T NAT (labelled V PSC ) is quantitatively related to springtime ozone loss (Rex et al, , 2006Tilmes et al, 2004).…”

Antarctic ozone hole as observed by IASI/MetOp for 2008–2010

“…As a result these instruments have large data gaps which can be filled using assimilated data (e.g. Kiesewetter et al, 2010Kiesewetter et al, , van der A, 2010. Nadir-looking thermal infrared (TIR) sounders such as IASI (Infrared Atmospheric Sounding Interferometer) onboard MetOp-A complement the available datasets, with the advantage that both day and night time measurements are available at high spatial resolution.…”