scholarly journals An evaluation of the simulation of the edge of the Antarctic vortex by chemistry-climate models

2008 ◽  
Vol 8 (6) ◽  
pp. 20155-20192 ◽  
Author(s):  
H. Struthers ◽  
G. E. Bodeker ◽  
J. Austin ◽  
S. Bekki ◽  
I. Cionni ◽  
...  
Keyword(s):  
Climate Models ◽  
Measurement Data ◽  
Chemical Processes ◽  
Data Sets ◽  
Dynamical Structure ◽  
Total Column Ozone ◽  
Ozone Loss ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column

Abstract. The dynamical barrier to meridional mixing at the edge of the Antarctic spring stratospheric vortex is examined. Diagnostics are presented which demonstrate the link between the shape of the meridional mixing barrier at the edge of the vortex and the meridional gradients in total column ozone across the vortex edge. Results derived from reanalysis and measurement data sets are compared with equivalent diagnostics from five coupled chemistry-climate models to test how well the models capture the interaction between the dynamical structure of the stratospheric vortex and the chemical processes occurring within the vortex. Results show that the accuracy of the simulation of the dynamical vortex edge varies widely amongst the models studied here. This affects the ability of the models to simulate the large observed meridional gradients in total column ozone. Three of the models in this study simulated the inner edge of the vortex to be more than 7° closer to the pole than observed. This is expected to have important implications for how well these models simulate the extent of severe springtime ozone loss that occurs within the Antarctic vortex.

scholarly journals The simulation of the Antarctic ozone hole by chemistry-climate models

2009 ◽  
Vol 9 (17) ◽  
pp. 6363-6376 ◽  
Author(s):  
H. Struthers ◽  
G. E. Bodeker ◽  
J. Austin ◽  
S. Bekki ◽  
I. Cionni ◽  
...  
Keyword(s):  
Climate Models ◽  
Polar Vortex ◽  
Ozone Hole ◽  
Total Column Ozone ◽  
Hole Area ◽  
Antarctic Ozone ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column ◽  
Antarctic Ozone Hole

Abstract. While chemistry-climate models are able to reproduce many characteristics of the global total column ozone field and its long-term evolution, they have fared less well in simulating the commonly used diagnostic of the area of the Antarctic ozone hole i.e. the area within the 220 Dobson Unit (DU) contour. Two possible reasons for this are: (1) the underlying Global Climate Model (GCM) does not correctly simulate the size of the polar vortex, and (2) the stratospheric chemistry scheme incorporated into the GCM, and/or the model dynamics, results in systematic biases in the total column ozone fields such that the 220 DU contour is no longer appropriate for delineating the edge of the ozone hole. Both causes are examined here with a view to developing ozone hole area diagnostics that better suit measurement-model inter-comparisons. The interplay between the shape of the meridional mixing barrier at the edge of the vortex and the meridional gradients in total column ozone across the vortex edge is investigated in measurements and in 5 chemistry-climate models (CCMs). Analysis of the simulation of the polar vortex in the CCMs shows that the first of the two possible causes does play a role in some models. This in turn affects the ability of the models to simulate the large observed meridional gradients in total column ozone. The second of the two causes also strongly affects the ability of the CCMs to track the observed size of the ozone hole. It is shown that by applying a common algorithm to the CCMs for selecting a delineating threshold unique to each model, a more appropriate diagnostic of ozone hole area can be generated that shows better agreement with that derived from observations.

scholarly journals Antarctic ozone depletion between 1960 and 1980 in observations and chemistry–climate model simulations

2016 ◽  
Vol 16 (24) ◽  
pp. 15619-15627 ◽  
Author(s):  
Ulrike Langematz ◽  
Franziska Schmidt ◽  
Markus Kunze ◽  
Gregory E. Bodeker ◽  
Peter Braesicke
Keyword(s):  
Ozone Depletion ◽  
Climate Model ◽  
Total Column Ozone ◽  
Antarctic Ozone ◽  
Climate Model Simulations ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column

Abstract. The year 1980 has often been used as a benchmark for the return of Antarctic ozone to conditions assumed to be unaffected by emissions of ozone-depleting substances (ODSs), implying that anthropogenic ozone depletion in Antarctica started around 1980. Here, the extent of anthropogenically driven Antarctic ozone depletion prior to 1980 is examined using output from transient chemistry–climate model (CCM) simulations from 1960 to 2000 with prescribed changes of ozone-depleting substance concentrations in conjunction with observations. A regression model is used to attribute CCM modelled and observed changes in Antarctic total column ozone to halogen-driven chemistry prior to 1980. Wintertime Antarctic ozone is strongly affected by dynamical processes that vary in amplitude from year to year and from model to model. However, when the dynamical and chemical impacts on ozone are separated, all models consistently show a long-term, halogen-induced negative trend in Antarctic ozone from 1960 to 1980. The anthropogenically driven ozone loss from 1960 to 1980 ranges between 26.4 ± 3.4 and 49.8 ± 6.2 % of the total anthropogenic ozone depletion from 1960 to 2000. An even stronger ozone decline of 56.4 ± 6.8 % was estimated from ozone observations. This analysis of the observations and simulations from 17 CCMs clarifies that while the return of Antarctic ozone to 1980 values remains a valid milestone, achieving that milestone is not indicative of full recovery of the Antarctic ozone layer from the effects of ODSs.

scholarly journals Indicators of Antarctic ozone depletion

2005 ◽  
Vol 5 (3) ◽  
pp. 3811-3845 ◽  
Author(s):  
G. E. Bodeker ◽  
H. Shiona ◽  
H. Eskes
Keyword(s):  
Data Base ◽  
Ozone Hole ◽  
Data Set ◽  
Total Column Ozone ◽  
Spatial Coverage ◽  
Antarctic Ozone ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column ◽  
Antarctic Ozone Hole

Abstract. An assimilated data base of total column ozone measurements from satellites has been used to generate a set of indicators describing attributes of the Antarctic ozone hole for the period 1979 to 2003, including (i) daily measures of the area over Antarctica where ozone levels are below 150DU, below 220DU, more than 30% below 1979 to 1981 norms, and more than 50% below 1979 to 1981 norms, (ii) the date of disappearance of 150DU ozone values, 220DU ozone values, values 30% below 1979 to 1981 norms, and values 50% below 1979 to 1981 norms, for each year, (iii) daily minimum total column ozone values over Antarctica, and (iv) daily values of the ozone mass deficit based on a O3<220DU threshold. The assimilated data base combines satellite-based ozone measurements from 4 Total Ozone Mapping Spectrometer (TOMS) instruments, 3 different retrievals from the Global Ozone Monitoring Experiment (GOME), and data from 4 Solar Backscatter Ultra-Violet (SBUV) instruments. Comparisons with the global ground-based Dobson spectrophotometer network are used to remove offsets and drifts between the different data sets to produce a global homogeneous data set that combines the advantages of good spatial coverage of satellite data with good long-term stability of ground-based measurements. One potential use of the derived indices is detection of the expected recovery of the Antarctic ozone hole. The suitability of the derived indicators to this task is discussed in the context of their variability and their susceptibility to saturation effects which makes them less responsive to decreasing stratospheric halogen loading. It is also shown that if the corrections required to match recent Earth Probe TOMS measurements to Dobson measurements are not applied, some of the indictors are affected so as to obscure detection of the recovery of the Antarctic ozone hole.

scholarly journals Early unusual ozone loss during the Arctic winter 2002/2003 compared to other winters

2004 ◽  
Vol 4 (5) ◽  
pp. 5019-5044
Author(s):  
F. Goutail ◽  
J.-P. Pommereau ◽  
F. Lefèvre ◽  
M. Van Roozendael ◽  
S. B. Andersen ◽  
...  
Keyword(s):  
Low Temperature ◽  
The Arctic ◽  
Total Column Ozone ◽  
Ozone Loss ◽  
Column Ozone ◽  
Transport Method ◽  
Total Column ◽  
Very Low Temperature

Abstract. Total column ozone reduction in the Arctic is evaluated each winter since 1993/1994 by the transport method (3-D CTM passive ozone minus measurements). The cumulative loss from 1 December to the end of the season ranges from 5–10% during warm winters like 1998/1999, 2000/2001 and 2001/2002 up to 30%–32% during cold winters like 1994/1995 and 1995/1996. The 23% cumulative loss observed during the winter 2002/2003 is similar in amplitude to the 20–24% measured in 1996/1997 and 1999/2000 but the timing is different. It started unusually early in December after the occurrence of very low temperature at all stratospheric levels between 550 K and 435 K allowing PSC formation and thus chlorine activation. The early ozone loss of 2002/2003 is well captured by current 3-D CTM models.

scholarly journals Indicators of Antarctic ozone depletion

2005 ◽  
Vol 5 (10) ◽  
pp. 2603-2615 ◽  
Author(s):  
G. E. Bodeker ◽  
H. Shiona ◽  
H. Eskes
Keyword(s):  
Data Base ◽  
Ozone Hole ◽  
Data Set ◽  
Total Column Ozone ◽  
Spatial Coverage ◽  
Antarctic Ozone ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column ◽  
Antarctic Ozone Hole

Abstract. An assimilated data base of total column ozone measurements from satellites has been used to generate a set of indicators describing attributes of the Antarctic ozone hole for the period 1979 to 2003, including (i) daily measures of the area over Antarctica where ozone levels are below 150 DU, below 220 DU, more than 30% below 1979 to 1981 norms, and more than 50% below 1979 to 1981 norms, (ii) the date of disappearance of 150 DU ozone values, 220 DU ozone values, values 30% below 1979 to 1981 norms, and values 50% below 1979 to 1981 norms, for each year, (iii) daily minimum total column ozone values over Antarctica, and (iv) daily values of the ozone mass deficit based on a O3<220 DU threshold. The assimilated data base combines satellite-based ozone measurements from 4 Total Ozone Mapping Spectrometer (TOMS) instruments, 3 different retrievals from the Global Ozone Monitoring Experiment (GOME), and data from 4 Solar Backscatter Ultra-Violet (SBUV) instruments. Comparisons with the global ground-based Dobson spectrophotometer network are used to remove offsets and drifts between the different data sets to produce a global homogeneous data set that combines the advantages of good spatial coverage of satellite data with good long-term stability of ground-based measurements. One potential use of the derived indices is detection of the expected recovery of the Antarctic ozone hole. The suitability of the derived indicators to this task is discussed in the context of their variability and their susceptibility to saturation effects which makes them less responsive to decreasing stratospheric halogen loading. It is also shown that if the corrections required to match recent Earth Probe TOMS measurements to Dobson measurements are not applied, some of the indictors are affected so as to obscure detection of the recovery of the Antarctic ozone hole.

scholarly journals A new ENSO index derived from satellite measurements of column ozone

2010 ◽  
Vol 10 (8) ◽  
pp. 3711-3721 ◽  
Author(s):  
J. R. Ziemke ◽  
S. Chandra ◽  
L. D. Oman ◽  
P. K. Bhartia
Keyword(s):  
Climate Models ◽  
Southern Oscillation ◽  
Ozone Monitoring Instrument ◽  
Total Column Ozone ◽  
Enso Events ◽  
Gas Measurements ◽  
Column Ozone ◽  
The Tropics ◽  
Total Column ◽  
Enso Index

Abstract. Column Ozone measured in tropical latitudes from Nimbus 7 total ozone mapping spectrometer (TOMS), Earth Probe TOMS, solar backscatter ultraviolet (SBUV), and Aura ozone monitoring instrument (OMI) are used to derive an El Nino-Southern Oscillation (ENSO) index. This index, which covers a time period from 1979 to the present, is defined as the "Ozone ENSO Index" (OEI) and is the first developed from atmospheric trace gas measurements. The OEI is constructed by first averaging monthly mean column ozone over two broad regions in the western and eastern Pacific and then taking their difference. This differencing yields a self-calibrating ENSO index which is independent of individual instrument calibration offsets and drifts in measurements over the long record. The combined Aura OMI and MLS ozone data confirm that zonal variability in total column ozone in the tropics caused by ENSO events lies almost entirely in the troposphere. As a result, the OEI can be derived directly from total column ozone instead of tropospheric column ozone. For clear-sky ozone measurements a +1 K change in Nino 3.4 index corresponds to +2.9 Dobson Unit (DU) change in the OEI, while a +1 hPa change in SOI coincides with a −1.7 DU change in the OEI. For ozone measurements under all cloud conditions these numbers are +2.4 DU and −1.4 DU, respectively. As an ENSO index based upon ozone, it is potentially useful in evaluating climate models predicting long term changes in ozone and other trace gases.

scholarly journals Multi-model assessment of stratospheric ozone return dates and ozone recovery in CCMVal-2 models

2010 ◽  
Vol 10 (19) ◽  
pp. 9451-9472 ◽  
Author(s):  
V. Eyring ◽  
I. Cionni ◽  
G. E. Bodeker ◽  
A. J. Charlton-Perez ◽  
D. E. Kinnison ◽  
...  
Keyword(s):  
21St Century ◽  
Climate Models ◽  
Lower Stratosphere ◽  
Stratospheric Ozone ◽  
Full Recovery ◽  
Steady Increase ◽  
Model Assessment ◽  
Total Column Ozone ◽  
Column Ozone ◽  
Total Column

Abstract. Projections of stratospheric ozone from a suite of chemistry-climate models (CCMs) have been analyzed. In addition to a reference simulation where anthropogenic halogenated ozone depleting substances (ODSs) and greenhouse gases (GHGs) vary with time, sensitivity simulations with either ODS or GHG concentrations fixed at 1960 levels were performed to disaggregate the drivers of projected ozone changes. These simulations were also used to assess the two distinct milestones of ozone returning to historical values (ozone return dates) and ozone no longer being influenced by ODSs (full ozone recovery). The date of ozone returning to historical values does not indicate complete recovery from ODSs in most cases, because GHG-induced changes accelerate or decelerate ozone changes in many regions. In the upper stratosphere where CO2-induced stratospheric cooling increases ozone, full ozone recovery is projected to not likely have occurred by 2100 even though ozone returns to its 1980 or even 1960 levels well before (~2025 and 2040, respectively). In contrast, in the tropical lower stratosphere ozone decreases continuously from 1960 to 2100 due to projected increases in tropical upwelling, while by around 2040 it is already very likely that full recovery from the effects of ODSs has occurred, although ODS concentrations are still elevated by this date. In the midlatitude lower stratosphere the evolution differs from that in the tropics, and rather than a steady decrease in ozone, first a decrease in ozone is simulated from 1960 to 2000, which is then followed by a steady increase through the 21st century. Ozone in the midlatitude lower stratosphere returns to 1980 levels by ~2045 in the Northern Hemisphere (NH) and by ~2055 in the Southern Hemisphere (SH), and full ozone recovery is likely reached by 2100 in both hemispheres. Overall, in all regions except the tropical lower stratosphere, full ozone recovery from ODSs occurs significantly later than the return of total column ozone to its 1980 level. The latest return of total column ozone is projected to occur over Antarctica (~2045–2060) whereas it is not likely that full ozone recovery is reached by the end of the 21st century in this region. Arctic total column ozone is projected to return to 1980 levels well before polar stratospheric halogen loading does so (~2025–2030 for total column ozone, cf. 2050–2070 for Cly+60×Bry) and it is likely that full recovery of total column ozone from the effects of ODSs has occurred by ~2035. In contrast to the Antarctic, by 2100 Arctic total column ozone is projected to be above 1960 levels, but not in the fixed GHG simulation, indicating that climate change plays a significant role.

scholarly journals Impact of using different ozone cross sections on ozone profile retrievals from Global Ozone Monitoring Experiment (GOME) ultraviolet measurements

2007 ◽  
Vol 7 (13) ◽  
pp. 3571-3578 ◽  
Author(s):  
X. Liu ◽  
K. Chance ◽  
C. E. Sioris ◽  
T. P. Kurosu
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Data Sets ◽  
Total Column Ozone ◽  
Section Data ◽  
Ozone Profile ◽  
Ozone Monitoring ◽  
Column Ozone ◽  
Flight Model ◽  
Total Column

Abstract. We investigate the effect of using three different cross section data sets on ozone profile retrievals from Global Ozone Monitoring Experiment (GOME) ultraviolet measurements (289–307 nm, 326–337 nm). These include Bass-Paur, Brion, and GOME flight model cross sections (references below). Using different cross sections can significantly affect the retrievals, by up to 12 Dobson Units (DU, 1 DU=2.69×1016 molecules cm−2) in total column ozone, up to 10 DU in tropospheric column ozone, and up to 100% in retrieved ozone values for individual atmospheric layers. Compared to using the Bass-Paur and GOME flight model cross sections, using the Brion cross sections not only reduces fitting residuals by 15–60% in the Huggins bands, but also improves retrievals, especially in the troposphere, as seen from validation against ozonesonde measurements. Therefore, we recommend using the Brion cross section for ozone profile retrievals from ultraviolet measurements. The total column ozone retrieved using the GOME flight model cross sections is systematically lower, by 7–10 DU, than that retrieved using the Brion and Bass-Paur cross sections and is also systematically lower than Total Ozone Mapping Spectrometer (TOMS) observations. This study demonstrates the need for improved ozone cross section measurements in the ultraviolet to improve profile retrievals of this key atmospheric constituent.

scholarly journals Impact of using different ozone cross sections on ozone profile retrievals from Global Ozone Monitoring Experiment (GOME) ultraviolet measurements

2007 ◽  
Vol 7 (1) ◽  
pp. 971-993
Author(s):  
X. Liu ◽  
K. Chance ◽  
C. E. Sioris ◽  
T. P. Kurosu
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Data Sets ◽  
Total Column Ozone ◽  
Section Data ◽  
Ozone Profile ◽  
Ozone Monitoring ◽  
Column Ozone ◽  
Flight Model ◽  
Total Column

Abstract. We investigate the effect of using three different cross section data sets on ozone profile retrievals from Global Ozone Monitoring Experiment (GOME) ultraviolet measurements (289–307 nm, 326–337 nm). These include Bass-Paur, Brion, and GOME flight model cross sections (references below). Using different cross sections can significantly affect the retrievals, by up to 12 Dobson Units (DU, 1 DU=2.69×1016 molecules cm−2) in total column ozone, up to 10 DU in tropospheric column ozone, and up to 100% in retrieved ozone values for individual atmospheric layers. Compared to using the Bass-Paur and GOME flight model cross sections, using the Brion cross sections not only reduces fitting residuals by 15–60% in the Huggins bands, but also improves retrievals, especially in the troposphere, as seen from validation against ozonesonde measurements. Therefore, we recommend using the Brion cross section for ozone profile retrievals from ultraviolet measurements. The total column ozone retrieved using the GOME flight model cross sections is systematically lower, by 7–10 DU, than that retrieved using the Brion and Bass-Paur cross sections and is also systematically lower than Total Ozone Mapping Spectrometer (TOMS) observations. This study demonstrates the need for improved ozone cross section measurements in the ultraviolet to improve profile retrievals of this key atmospheric constituent.

scholarly journals On the relationship between total ozone and atmospheric dynamics and chemistry at mid-latitudes – Part 1: Statistical models and spatial fingerprints of atmospheric dynamics and chemistry

2013 ◽  
Vol 13 (1) ◽  
pp. 147-164 ◽  
Author(s):  
L. Frossard ◽  
H. E. Rieder ◽  
M. Ribatet ◽  
J. Staehelin ◽  
J. A. Maeder ◽  
...  
Keyword(s):  
North Atlantic ◽  
Statistical Models ◽  
Grid Cell ◽  
Atmospheric Dynamics ◽  
Total Column Ozone ◽  
The North ◽  
The North Atlantic ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column

Abstract. We use statistical models for mean and extreme values of total column ozone to analyze "fingerprints" of atmospheric dynamics and chemistry on long-term ozone changes at northern and southern mid-latitudes on grid cell basis. At each grid cell, the r-largest order statistics method is used for the analysis of extreme events in low and high total ozone (termed ELOs and EHOs, respectively), and an autoregressive moving average (ARMA) model is used for the corresponding mean value analysis. In order to describe the dynamical and chemical state of the atmosphere, the statistical models include important atmospheric covariates: the solar cycle, the Quasi-Biennial Oscillation (QBO), ozone depleting substances (ODS) in terms of equivalent effective stratospheric chlorine (EESC), the North Atlantic Oscillation (NAO), the Antarctic Oscillation (AAO), the El Niño/Southern Oscillation (ENSO), and aerosol load after the volcanic eruptions of El Chichón and Mt. Pinatubo. The influence of the individual covariates on mean and extreme levels in total column ozone is derived on a grid cell basis. The results show that "fingerprints", i.e., significant influence, of dynamical and chemical features are captured in both the "bulk" and the tails of the statistical distribution of ozone, respectively described by mean values and EHOs/ELOs. While results for the solar cycle, QBO, and EESC are in good agreement with findings of earlier studies, unprecedented spatial fingerprints are retrieved for the dynamical covariates. Column ozone is enhanced over Labrador/Greenland, the North Atlantic sector and over the Norwegian Sea, but is reduced over Europe, Russia and the Eastern United States during the positive NAO phase, and vice-versa during the negative phase. The NAO's southern counterpart, the AAO, strongly influences column ozone at lower southern mid-latitudes, including the southern parts of South America and the Antarctic Peninsula, and the central southern mid-latitudes. Results for both NAO and AAO confirm the importance of atmospheric dynamics for ozone variability and changes from local/regional to global scales.

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