<title>Update on the global ozone climatology and on concurrent ozone and temperature trends</title>

Abstract

An attempt is made to construct a zonal and monthly mean ozone climatology for use in general circulation models, based on a combination of ozonesonde and satellite observations. One important advantage of such a climatology is a more realistic ozone distribution around the tropopause, where heating rates and climate forcing are most sensitive to changes in gas concentrations. Also, a linear trend study is performed, for the periods 1970-83 and 1980-93 separately, on concurrent ozone and temperature data obtained from a selection of ozonesonde stations. On average for northern poiar-to mid-latitudes, these trends are insignificant for stratospheric ozone and temperature in the first period, but for the second period show a stratosphetic ozone depletion and stratospheric cooling of around -0.5 %/yearand -0. 15 K/year respectively. As for the troposphere in the same region, ozone shows an increase ( 1.5 %/year) in the mid-troposphere but temperature trends are insignificant over the first period, versus no ozone trend but a clearly significant near-surface warming (-0.2 K/year) in the second period. This average situation is however not representative for the separate regions it is composed of, i.e., Canada (4 stations), Japan (3 stations) and the U.S. (1 station). Above Syowa station at the Antarctic coast, the acceleration in stratospheric ozone depletion as well as stratospheric cooling over the past two decades is clearly evident: from hardly significant ozone and temperature trends in the first period to values ofup to -4 %/year and -0.4 K/year respectively in the second period. In regions where nearsurface ozone increase is evident over the past two decades, it is often accompanied by a significant near-surface warming. L INTRODUCTIONMost general circulation models (GCM's) currently use a prescribed ozone distribution for the calculation of radiative heating rates. Ideally this distribution should be a function of latitude, longitude, height and time. However, none of the observed ozone data provide the required spatial and temporal coverage for this. One commonly used dataset, the CIRA ozone reference 910hI was compiled using data from five different satellite instruments (LIMS, SBUV, AE-2 SAGE, SME-UVS and SME-IR), retrieving ozone profiles between 20 to 0.003 hPa (24 levels) from November 1978 to December 1983. An improved version of the CIRA model, including data on 3 additional pressure levels: 30, 50 and 70 hPa (Keating, personal communication), and extended to high latitudes in the polar night (after Shine, personal communication), is currently being used in the Berlin tropo-strato-mesospheric GCM. Use ofthis climatology results in a fairly realistic vertical temperature structure in the stratosphere and mesosphere.2' Up to now, satellite instruments are not capable ofmeasuring ozone in the troposphere and near the tropopause, where the climate forcing and radiative heating rates are very sensitive to the assumed ozone distribution.6'20 In order to overcome this deficit, an attempt is made to construct...

Long-term climatology of air mass transport through the Tropical Tropopause Layer (TTL) during NH winter

“…A larger geographical spread of the trajectories is found for the cases using climatological ozone fields ( Fig. 1b and d), taking the ECMWF standard ozone climatology (Fortuin and Langematz, 1995) as input instead of the assimilated ozone fields ( Fig. 1a and c).…”

“…The effect of using the ECMWF standard ozone climatology is illustrated by the green and orange lines, which maximize at 1 and 1.25 K/day with lower frequencies. In the tropical tropopause region there is slightly more ozone in the standard climatology compared to the assimilated fields (Fortuin and Langematz, 1995;Oikonomou and O'Neill, 2006), which leads to a stronger heating, hence upwelling in the TTL. For the rest of this study we are using the prognostic ECMWF ozone fields as input data.…”

Online coupled regional meteorology chemistry models in Europe: current status and prospects

“…modes), mineral (nuc./ acc./ coa. modes), mineral (transported), sulfate droplets C: Grid and sub-grid scale bulk G: None A: Only through temperature change caused by LW/SW C: Grid and sub-grid scale bulk SW, LW, PH: Model time step GEM Kaminski et al (2008) Correlated K (Li and Barker, 2005) with O3, H2O and aerosols from chemistry Correlated K (Li and Barker, 2005) with O3, H2O and aerosols from chemistry G,A,C all taken into account in Jvalue calculations using method of Landgraf and Crutzen, 1998 SW, LW, PH: model time step Lafore et al (1998) G: Climatology for O3 (Fortuin and Langematz, 1994), constant background for CO2, CH4, N2O, CFC11,CFC12 A: With prognostic aerosol (Tulet et al, 2005) , radiative properties of aerosols according to Mie theory (Aouizerats et al, 2010). Without aerosol scheme, climatological aerosols.…”

“…G: Climatology for O3 (Fortuin and Langematz, 1994), constant background for CO2, CH4, N2O, CFC11,CFC12 A: climatological aerosols. C: Effective radius calculated from the 2-moment microphysical scheme when explicitly used.…”

Sensitivity of the Freie Universität Berlin Climate Middle Atmosphere Model (FUB-CMAM) to different gravity-wave drag parameterisations

“…An improved treatment of radiative transfer (Langematz, 2000) eliminated the warm polar bias of the previous model version. Climatological ozone fields are employed, updated from Fortuin and Langematz (1994). Averaged (1979Averaged ( -1991 sea-surface temperatures based on the Atmospheric Modelling Intercomparison Project (AMIP) are employed to avoid the bias of sampling a particular phase of El Niño.…”