Interannual variability of stratospheric and tropospheric ozone determined from satellite measurements (original) (raw)
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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
Interannual variability in high latitude stratospheric ozone
2005
We apply the principal component analysis (PCA) to the total column ozone data from the combined Merged Ozone Data (MOD) and European Center for Medium-Range Weather Forecasts (ECMWF) assimilated ozone. The interannual variability (IAV) of O3 in the high latitude is characterized by four main modes in Northern Hemisphere (NH) and Southern Hemisphere (SH). Attributable to dominant dynamical effects, these
Journal of Geophysical Research, 2007
1] A global stratospheric ozone data set for 1979-2005 is described. Interannual variations are derived from analysis of Stratospheric Aerosol and Gas Experiment (SAGE I and II) profile measurements, combined with polar ozonesonde data from Syowa (69°S) and Resolute (75°N). These interannual changes are combined with a seasonally varying ozone climatology from Fortuin and Kelder [1998] to provide a monthly global data set. These data are intended for use in global modeling studies and for analysis of global variability and trends. In order to generate continuous fields from the gappy SAGE data, we use a regression fit that includes decadal trends, solar cycle, and QBO terms, and the spatial structure of these variations is studied in detail. Decadal trends are modeled using an equivalent effective stratospheric chlorine proxy. Ozone variability from the vertically integrated SAGE/sonde data set is compared with results derived from a merged Total Ozone Mapping Spectrometer/solar backscatter ultraviolet column ozone data set, showing good overall agreement (in particular for trends in extratropics). We also compare the SAGE data with ozonesonde measurements over Northern Hemisphere midlatitudes and find excellent agreement for lower stratospheric variability and trends. In the tropics, the SAGE ozone data show relatively large percentage decreases in the lower stratosphere. However, the vertically integrated SAGE data do not agree with column ozone trends in the tropics, so there is less confidence in the SAGE results in this region.
Atmospheric Chemistry and Physics, 2006
Global total ozone measurements from various satellite instruments such as SBUV, TOMS, and GOME show an increase in zonal mean total ozone at northern hemispheric (NH) mid to high latitudes since the mid-nineties. This increase could be expected from the peaking and start of decline in the effective stratospheric halogen loading, but the rather rapid increase observed in NH zonal mean total ozone suggests that another physical mechanism such as winter planetary wave activity has increased which has led to higher stratospheric Arctic temperatures. This has enhanced ozone transport into higher latitudes in recent years as part of the residual circulation and at the same time reduced the frequency of cold Arctic winters with enhanced polar ozone loss. Results from various multi-variate linear regression analyses using SBUV V8 total ozone with explanatory variables such as a linear trend or, alternatively, EESC (equivalent effective stratospheric chlorine) and on the other hand planetary wave driving (eddy heat flux) or, alternatively, polar ozone loss (PSC volume) in addition to proxies for stratospheric aerosol loading, QBO, and solar cycle, all considered to be main drivers for ozone variability, are presented. It is shown that the main contribution to the recent increase in NH total ozone is from the combined effect of rising tropospheric driven planetary wave activity associated with reduced polar ozone loss at high latitudes as well as increasing solar activity. This conclusion can be drawn regardless of the use of linear trend or EESC terms in our statistical model. It is also clear that more years of data will be needed to further improve our estimates of the relative contributions of the individual processes to decadal ozone variability. The question remains if the observed increase in planetary wave driving is Correspondence to: S. Dhomse (sandip@iup.physik.uni-bremen.de) part of natural decadal atmospheric variability or will persist. If the latter is the case, it could be interpreted as a possible signature of climate change.
Global distribution of total ozone and lower stratospheric temperature variations
Atmospheric Chemistry and Physics, 2003
This study gives an overview of interannual variations of total ozone and 50 hPa temperature. It is based on newer and longer records from the 1979 to 2001 Total Ozone Monitoring Spectrometer (TOMS) and Solar Backscatter Ultraviolet (SBUV) instruments, and on US National Center for Environmental Prediction (NCEP) reanalyses. Multiple linear least squares regression is used to attribute variations to various natural and anthropogenic explanatory variables. Usually, maps of total ozone and 50 hPa temperature variations look very similar, reflecting a very close coupling between the two. As a rule of thumb, a 10 Dobson Unit (DU) change in total ozone corresponds to a 1 K change of 50 hPa temperature. Large variations come from the linear trend term, up to −30 DU or −1.5 K/decade, from terms related to polar vortex strength, up to 50 DU or 5 K (typical, minimum to maximum), from tropospheric meteorology, up to 30 DU or 3 K, or from the Quasi-Biennial Oscillation (QBO), up to 25 DU or 2.5 K. The 11-year solar cycle, up to 25 DU or 2.5 K, or El Niño/Southern Oscillation (ENSO), up to 10 DU or 1 K, are contributing smaller variations. Stratospheric aerosol after the 1991 Pinatubo eruption lead to warming up to 3 K at low latitudes and to ozone depletion up to 40 DU at high latitudes. Variations attributed to QBO, polar vortex strength, and to a lesser degree to ENSO, exhibit an inverse correlation between low latitudes and higher latitudes. Variations related to the solar cycle or 400 hPa temperature, however, have the same sign over most of the globe. Variations are usually zonally symmetric at low and mid-latitudes, but asymmetric at high latitudes. There, position and strength of the stratospheric anticyclones over the Aleutians and south of Australia appear to vary with the phases of solar cycle, QBO or ENSO.
Atmospheric Chemistry and Physics, 2006
We report results from a multiple linear regression analysis of long-term total ozone observations (1979 to 2000, by TOMS/SBUV), of temperature reanalyses (1958 to 2000, NCEP), and of two chemistry-climate model simulations (1960 to 1999, by ECHAM4.L39(DLR)/CHEM (=E39/C), and MAECHAM4-CHEM). The model runs are transient experiments, where observed sea surface temperatures, increasing source gas concentrations (CO 2 , C FCs, CH 4 , N 2 O, NO x), 11-year solar cycle, volcanic aerosols and the quasi-biennial oscillation (QBO) are all accounted for. MAECHAM4-CHEM covers the atmosphere from the surface up to 0.01 hPa (≈80 km). For a proper representation of middle atmosphere (MA) dynamics, it includes a parametrization for momentum deposition by dissipating gravity wave spectra. E39/C, on the other hand, has its top layer centered at 10 hPa (≈30 km). It is targeted on processes near the tropopause, and has more levels in this region. Despite some problems, both models generally reproduce the observed amplitudes and much of the observed lowlatitude patterns of the various modes of interannual variability in total ozone and lower stratospheric temperature. In most aspects MAECHAM4-CHEM performs slightly better than E39/C. MAECHAM4-CHEM overestimates the longterm decline of total ozone, whereas E39/C underestimates the decline over Antarctica and at northern mid-latitudes. The true long-term decline in winter and spring above the
A global ozone climatology from ozone soundings via trajectory mapping: a stratospheric perspective
Atmospheric Chemistry and Physics, 2013
This study explores a domain-filling trajectory approach to generate a global ozone climatology from relatively sparse ozonesonde data. Global ozone soundings comprising 51 898 profiles at 116 stations over 44 yr are used, from which forward and backward trajectories are calculated from meteorological reanalysis data to map ozone measurements to other locations and so fill in the spatial domain. The resulting global ozone climatology is archived monthly for five decades from the 1960s to the 2000s on a grid of 5 • × 5 • × 1 km (latitude, longitude, and altitude), from the surface to 26 km altitude. It is also archived yearly for the same period. The climatology is validated at 20 selected ozonesonde stations by comparing the actual ozone sounding profile with that derived through trajectory mapping of ozone sounding data from all stations except the one being compared. The two sets of profiles are in good agreement, both overall with correlation coefficient r = 0.991 and root mean square (RMS) of 224 ppbv and individually with r from 0.975 to 0.998 and RMS from 87 to 482 ppbv. The ozone climatology is also compared with two sets of satellite data from the Satellite Aerosol and Gas Experiment (SAGE) and the Optical Spectrography and InfraRed Imager System (OSIRIS). The ozone climatology compares well with SAGE and OSIRIS data in both seasonal and zonal means. The mean differences are generally quite small, with maximum differences of 20 % above 15 km. The agreement is better in the Northern Hemisphere, where there are more ozonesonde stations, than in the Southern Hemisphere; it is also better in the middle and high latitudes than in the tropics where reanalysis winds are less accurate. This ozone climatology captures known features in the stratosphere as well as seasonal and decadal variations of these features. The climatology clearly shows the depletion of ozone from the 1970s to the mid 1990s and ozone increases in the 2000s in the lower stratosphere. When this climatology is used as the upper boundary condition in an Environment Canada operational chemical forecast model, the forecast is improved in the vicinity of the upper troposphere-lower stratosphere (UTLS) region. This ozone climatology is latitudinally, longitudinally, and vertically resolved and it offers more complete high latitude coverage as well as a much longer record than current satellite data. As the climatology depends on neither a priori data nor photochemical modeling, it provides independent information and insight that can supplement satellite data and model simulations of stratospheric ozone.
Atmospheric Chemistry and Physics Discussions, 2018
Temperature and ozone changes in the upper troposphere and lower stratosphere (UTLS) are important components and sensitive indicators of climate change. In this paper, variability and trends of temperature and ozone in the UTLS were investigated for the period 2002-2017 using the high quality, high vertical resolution GPS RO data, improved merged satellite data sets (SWOOSH and C3S) and reanalysis data sets (including the newest ERA5, MERRA2 and ERA-Interim). All three reanalyses show good agreement with the GPS RO measurements in absolute values, annual cycle as well as interannual variabilities of temperature. However, relatively large biases exist for the period 2002-2006, which reveals an evident discontinuity of temperature time series in reanalyses. Based on the multiple linear regression methods, a significant warming of 0.2-0.3 K/decade is found in most areas of the troposphere with stronger increase of 0.4-0.5 K/decade in mid-latitudes of both hemispheres. In contrast, the stratospheric temperature decreases at a rate of 0.1-0.3 K/decade except that in the lower most stratosphere (100-50 hPa) in the tropics and parts of mid-latitude in the Northern Hemisphere (NH). ERA5 shows improved quality compared with ERA-Interim and performs the best agreement with the GPS RO data for the recent trends of temperature. Similar with temperature, reanalyses ozone are also affected by the change of assimilated observations and methods. Negative trends of ozone are found in NH at 150-100 hPa while positive trends are evident in the tropical lower stratosphere. Asymmetric trends of ozone can be found for both hemispheres in the middle stratosphere, with significant ozone decrease in NH mid-latitudes and increase of ozone in the Southern Hemisphere (SH) mid-latitudes. According to model simulations, the temperature increase in the troposphere as well as ozone decrease in the NH stratosphere could be mainly connected to the increase of Sea Surface Temperature (SST) and subsequent changes of atmospheric circulations.