Assimilation of stratospheric ozone from MIPAS into a global general-circulation model: The September 2002 vortex split (original) (raw)
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Journal of Geophysical Research, 2002
1] A high-resolution three-dimensional off-line chemical transport simulation has been performed with the SLIMCAT model to examine transport and mixing of ozone depleted air in the lower stratosphere on breakup of the polar vortex in spring/summer 2000. The model included ozone, N 2 O, and F11 tracers and used simplified chemistry parameterizations. The model was forced by T106 European Centre for Medium-Range Weather Forecasts analyses. The model results show that, by the end of June, above 420 K, much of the ozonedepleted air is transported from polar regions to the subtropics. In contrast, below 420 K, most of the ozone-depleted air remains poleward of approximately 55°N. It is suggested that the influence of the upper extension of the tropospheric subtropical jet provides a transport barrier at lower levels, while strong stirring on breakup of the polar vortex is important at upper levels. The mean meridional circulation modifies the distribution of ozone-depleted air by moving it up the subtropics and down in the extratropics. The model simulation is validated by comparing vertical profiles of ozone loss against ozonesonde measurements. The model results are consistent with many of the features present in the ozonesonde measurements. F11-N 2 O correlation plots are examined in the model and they show distinct canonical correlation curves for the polar vortex, midlatitudes, and the tropics. Comparison against balloon and aircraft measurements show that the model reproduces the separation between the vortex and midlatitude curves; however, the ratio of N 2 O to F11 lifetimes is somewhat too small in the model. It is shown that anomalies from the midlatitude canonical correlation curve can be used to identify remnants of polar vortex air which has mixed with midlatitude air. At the end of June there is excellent agreement in the position of air with anomalous F11-N 2 O tracer correlation and ozone-depleted air from the polar vortex. Transport of ozone-depleted air on the breakup of the stratospheric polar vortex in spring/summer 2000,
Impact of mesospheric intrusions on ozone-tracer relations in the stratospheric polar vortex
Journal of Geophysical Research, 2007
1] Ozone-tracer relations are used to quantify chemical ozone loss in the polar vortices. The underlying assumptions for the application of this technique were extensively discussed in recent years. However, the impact intrusions of mesospheric air into the polar stratosphere have on estimates of chemical ozone loss based on the ozone-tracer technique has not hitherto been studied. Here, we revisit observations of an intrusion of mesospheric air down to altitudes of 25km(25 km (25km(600 K potential temperature) in the Arctic vortex in 2003. The mesospheric intrusion was identified in three balloon profiles in January and March 2003 as a strong enhancement in CO. In contrast, NO y was not enhanced in the mesospheric air relative to surrounding air masses as shown by the measurement in late March 2003. The measurements influenced by mesospheric air show ozone mixing ratios ranging between 3.6 and 5.6 ppm, which are clearly greater than those found in the ''early vortex'' reference relation employed to deduce chemical ozone loss. Thus the impact of intrusions of mesospheric air into the polar vortex on chemical ozone loss estimates based on ozone-tracer relations are likely small; the correlations cannot be affected in a way that would lead to an overestimate of ozone depletion. Therefore ozone-tracer relations may be used for deducing chemical ozone loss in Arctic winter 2002-2003. Here we use ILAS-II satellite measurements to deduce an average chemical ozone loss in the vortex core for the partial column 380-550 K of 37 ± 11 Dobson units in March and of 50 ± 10 Dobson units in April 2003. Citation: Müller, R., et al. (2007), Impact of mesospheric intrusions on ozone-tracer relations in the stratospheric polar vortex,
Assimilation of ozone profiles and total column measurements into a global general circulation model
Journal of Geophysical Research, 2002
1] Ozone profiles from the Microwave Limb Sounder (MLS) instrument flown on board the Upper Atmosphere Research Satellite (UARS) and total ozone columns measured by the Global Ozone Monitoring Experiment (GOME) on board the Second European Remote Sensing Satellite (ERS-2) have been assimilated using a troposphere-stratosphere data assimilation system. The analysis system is based on the global analysis system used for operational analysis of the stratosphere at the Meteorological Office from 1991 to 2000. Three assimilation runs have been completed for a three-week period in April 1997 to test the advantage of using a combination of MLS and GOME observations, compared with the assimilation of each observation data set separately. The statistical information produced by the assimilation system shows that the combination of MLS and GOME observations via the assimilation process produces ozone fields that show improvement compared with analysis fields produced by the assimilation of either MLS or GOME separately. Comparison of the analyzed ozone fields with independent observations (ozonesondes, Halogen Occultation Experiment (HALOE) profiles and Total Ozone Mapping Spectrometer (TOMS) total ozone column measurements) corroborates these results and shows that the combined MLS and GOME ozone analyses provide a realistic representation of the atmospheric ozone distribution. The global root-mean-square residual (difference between the analyses and independent observations) against HALOE and TOMS observations is comparable to the quoted errors in the HALOE and TOMS instruments (5% in each case).
Data assimilation of stratospheric ozone using a high-resolution transport model
Geophysical Research Letters, 2002
We describe a method for assimilating sequentially tracer measurements in isentropic chemistry-transport models (CTMs) of the stratosphere. The parametrisation of the forecast error covariance and its evolution is largely based on simplifications described in Menard and Chang [2000] and Khattatov et al. [2000]. The model used here is a high resolution isentropic advection model which is driven by ECMWF (European Center for Medium range Weather Forcast) meteorological analyses. The assimilation on isentropic surfaces allow us to exploit the wellestablished correlation between tracer mixing ratio and potential vorticity in the formulation of the forecast error covariance. Multiple 20-day sequential assimilations of MLS (Microwave Limb Sounder onboard UARS satellite) ozone data during an ozone depletion event are performed. c 2 (chi-square) and OmF (observation minus forecast) statistics are used to optimise the assimilation system by adjusting parameters of the error covariance. The quality of the analysis is found to be significantly improved when the strong correlation between ozone and potential vorticity is taken into account.
Atmospheric Chemistry and Physics, 2006
Trends in ozone columns and vertical distributions were calculated for the period 1979-2004 based on the ozone data set CATO (Candidoz Assimilated Three-dimensional Ozone) using a multiple linear regression model. CATO has been reconstructed from TOMS, GOME and SBUV total column ozone observations in an equivalent latitude and potential temperature framework and offers a pole to pole coverage of the stratosphere on 15 potential temperature levels. The regression model includes explanatory variables describing the influence of the quasi-biennial oscillation (QBO), volcanic eruptions, the solar cycle, the Brewer-Dobson circulation, Arctic ozone depletion, and the increase in stratospheric chlorine. The effects of displacements of the polar vortex and jet streams due to planetary waves, which may significantly affect trends at a given geographical latitude, are eliminated in the equivalent latitude framework. The QBO shows a strong signal throughout most of the lower stratosphere with peak amplitudes in the tropics of the order of 10-20% (peak to valley). The eruption of Pinatubo led to annual mean ozone reductions of 15-25% between the tropopause and 23 km in northern mid-latitudes and to similar percentage changes in the southern hemisphere but concentrated at altitudes below 17 km. Stratospheric ozone is elevated over a broad latitude range by up to 5% during solar maximum compared to solar minimum, the largest increase being observed around 30 km. This is at a lower altitude than reported previously, and no negative signal is found in the tropical lower stratosphere. The Brewer-Dobson circulation shows a dominant contribution to interannual variability at both high and low latitudes and accounts for some of the ozone increase seen in the northern hemisphere since the mid-1990s. Arctic ozone depletion significantly affects the high northern latitudes between January and March and ex
Journal of Geophysical Research: Atmospheres, 2020
Compatibility of the stratospheric ozone profile data from the Ozone Mapping and Profiler Suite Limb Profiler (OMPS-LP) and the Microwave Limb Sounder (MLS) is assessed in the context of a continuity requirement for future reanalyses. A methodology for the assimilation of OMPS-LP data into the Goddard Earth Observing System data assimilation system with a stratospheric chemistry module is developed. It is demonstrated that a simple homogenization technique significantly reduces the bias between OMPS-LP and MLS analyses. With the homogenization applied, the mean difference between the two analyses is within 3% and the difference standard deviation within 10%, consistent with the estimated uncertainties of the satellite ozone data. Larger differences are seen in the tropical lower stratosphere. The MLS and OMPS-LP assimilation experiments agree very well with independent data from ozonesondes and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer. Heterogeneous ozone depletion during polar spring in both hemispheres as well as ozone transport during the 2016 quasi-biennial oscillation disruption event are realistically represented in both analyses. This work establishes a step toward achieving continuity of the post-2004 ozone record in future reanalyses, necessary for trend and long-term ozone variability studies, although further development is needed to address a drift in the OMPS-LP ozone data. Plain Language Summary Following a period of decline in the second half of the twentieth century, stratospheric ozone has begun its road to recovery owing to the successful implementation of the Montreal Protocol and its amendments. Monitoring of the evolution of stratospheric ozone continues to be of interest to the scientific community and the public. This paper presents a step toward a future multidecadal analysis of stratospheric ozone using data from two types of satellite instruments: The Microwave Limb Sounder (MLS, 2004 to present) and the Ozone Mapping and Profiler Suite Limb Profiler (OMPS-LP, 2012 to present with projected future missions). We show that a simple homogenization methodology can be applied to remove the relative bias between the two data sets. We produce global records of stratospheric ozone for the year 2016 using a data assimilation methodology, which combines the satellite observations with an atmospheric chemistry model output. We show that MLS and OMPS-LP assimilation experiments are in excellent agreement with independent data and with each other, providing a strong basis for a consistent future multidecadal ozone reanalysis, in which OMPS-LP data will replace MLS once the latter becomes unavailable. We also emphasize that further work is needed to reduce a long-term spurious drift in OMPS-LP data.
Gome Ozone Data Assimilation And The Ozone Mini-Hole Of 30 November 1999
Ozone transport models driven by high-quality analysed meteorological wind fields have been demonstrated to produce realistic ozone distributions. We describe a data assimilation system (TM3-DAM, version 3) which is currently in use to assimilate near-real time GOME ozone data, and which produces (three-day or longer) ozone forecasts. The model is a tracer transport model, called TM3, with a parameterised description of stratospheric ozone chemistry. The model is driven by meteorological fields from the ECMWF weather prediction model. The assimilation is based on near-real time level-2 ozone data from the GOME instrument on the ESA ERS-2 satellite. This data assimilation model is used to investigate the record low ozone values as observed over northwestern Europe by GOME, Brewer instruments and ozone sondes. Three possible causes, uplifting of the tropopause, chemical ozone destruction and horizontal transport, are investigated. The main cause of this event is found to be pole-ward ...
Impact of stratospheric dynamics and chemistry on northern hemisphere midlatitude ozone loss
Journal of Geophysical Research, 1998
The importance of dynamics for stratospheric ozone distribution in the northern hemisphere is investigated by using multiannual simulations of the coupled dynamic-chemical general circulation model ECHAM3/CHEM. This model includes a parameterization for heterogeneous reactions on the surfaces of polar stratospheric clouds (PSCs) and on sulfate aerosols. A warm and a cold stratospheric winter are examined to estimate the range of chemical ozone loss in the model due to heterogeneous reactions on PSCs. Ozone depletion in the model mainly occurs inside the polar vortex. An additional ozone reduction due to heterogeneous reactions on PSCs is found outside the polar vortex. Secondary vortex formation and vortex contraction after an elongation lead to a transport of air masses with chemically reduced ozone values out of the vortex. Except for such events the edge of the modeled polar vortex acts as a barrier to transport. During the formation of secondary vortices no additional heterogeneous reactions occur therein. Other dynamic events, such as the elongation of the polar vortex and its displacement to lower latitudes, lead t,o an intense ozone depletion. A minor stratospheric warming in the model causes a total aleactivation of chlorine compounds and prevents further ozone depletion. In midlatitudes, the amplitude of short-term variations of total ozone is amplified by PSC heterogeneous chemical ozone reduction. 1. Introduction After the discovery of the Antarctic ozone hole [Farman et al., 1985], several studies addressed the question of the importance of distinct chemical and dynamic reasons for the observed ozone depletion [e.g., Crutzen and Arnold, 1986; Solomon, 1986] (see World Meteorological Organization (WMO) [1992] for more detailed discussion). From satellite measurements it was obvious that the ozone decrease over the last decades was not restricted to the southern hemisphere high latitudes but also occurs in the northern hemisphere and at midlatitudes of both hemispheres [Stolarski et al., 1991, 1992; Randel and Wu, 1995]. This finding led to an intense debate on the characteristics of the stratospheric polar vortex and related effects on stratospheric transport processes at its edge, i.e., whether the polar vortex acts as a "containment vessel" [Mcintyre, 1989; Schoeberl et al., 1989] or as a "flowing processor" [Tuck, 1989; Proffittet al., 1989]. A comprehensive discussion was given by Schoeberl et al. [1992], Randel [1993], and Wanben Paper number 98JD01830. 0148-0227 / 98 / 98 JD-01830509.00 et al. [1997]. Measurements revealed that near the edge of the vortex the meridional poleward transport in winter has been reduced, resulting in different compositions of the air inside and outside the polar vortex (e.g., for southern hemisphere conditions [Tuck, 1989; Margitan et al., 1989] and for northern hemisphere conditions [Proffitt et al., 1990]). However, model studies [Juckes and Mcintyre, 1987] and observational studies [e.g., Tuck, 1989] clearly showed that the polar vortex
Three-dimensional simulations of wintertime ozone variability in the lower stratosphere
Journal of Geophysical Research, 1991
The evolution of ozone has been calculated for the winters of 1979 and 1989 using winds derived from our stratospheric data assimilation system (STRATAN). The ozone fields calculated using this technique are found to compare well with satellite-measured fields for simulations of 2-3 months. Here we present comparisons of model fields with both satellite and sonde measurements to verify that stratospheric transport processes are properly represented by this modeling technique. Attention is focussed on the northern hemisphere middle and high latitudes at the 10-hPa level and below, where transport processes are most important to the ozone distribution. First-order quantities and derived budgets from both the model and satellite data are presented. By sampling the model with a limb-viewing satellite and then Kalman filtering the "observations" of the model, it is shown that transient subplanetary-scale features that are essential to the ozone budget are missed by the satellite system.