Response of Arctic ozone to sudden stratospheric warmings

Abstract. Sudden stratospheric warmings (SSWs) are the main source of intra-seasonal and interannual variability in the extratropical stratosphere. The profound alterations to the stratospheric circulation that accompany such events produce rapid changes in the atmospheric composition. The goal of this study is to deepen our understanding of the dynamics that control changes of Arctic ozone during the life cycle of SSWs, providing a quantitative analysis of advective transport and mixing. We use output from four ensemble members (60 years each) of the Whole Atmospheric Community Climate Model version 4 performed for the Chemistry Climate Model Initiative and also use reanalysis and satellite data for validation purposes. The composite evolution of ozone displays positive mixing ratio anomalies of up to 0.5–0.6 ppmv above 550 K (∼ 50 hPa) around the central warming date and negative anomalies below (−0.2 to −0.3 ppmv), consistently in observations, reanalysis, and the model. Our analysis shows a clear temporal offset between ozone eddy transport and diffusive ozone fluxes. The initial changes in ozone are mainly driven by isentropic eddy fluxes linked to enhanced wave drag responsible for the SSW. The recovery of climatological values in the aftermath of SSWs is slower in the lower than in the upper stratosphere and is driven by the competing effects of cross-isentropic motions (which work towards the recovery) and isentropic irreversible mixing (which delays the recovery). These features are enhanced in strength and duration during sufficiently deep SSWs, particularly those followed by polar-night jet oscillation (PJO) events. It is found that SSW-induced ozone concentration anomalies below 600 K (∼ 40 hPa), as well as total column estimates, persist around 1 month longer in PJO than in non-PJO warmings.

Download Full-text

Response of Arctic ozone to sudden stratospheric warmings

10.5194/acp-2018-786 ◽

2018 ◽

Author(s):

Alvaro de la Cámara ◽

Marta Abalos ◽

Peter Hitchcock ◽

Natalia Calvo ◽

Rolando R. Garcia

Keyword(s):

Climate Model ◽

Wave Drag ◽

Atmospheric Composition ◽

Advective Transport ◽

Eddy Transport ◽

Eddy Fluxes ◽

Stratospheric Circulation ◽

Transport And Mixing ◽

Jet Oscillation ◽

Temporal Offset

Abstract. Sudden stratospheric warmings (SSW) are the main source of intra-seasonal and interannual variability in the extratropical stratosphere. The profound alterations to the stratospheric circulation that accompany such events produce rapid changes in the atmospheric composition. The goal of this study is to deepen our understanding of the dynamics that control changes of Arctic ozone during the life cycle of SSWs, providing a quantitative analysis of advective transport and mixing. We use output from four ensemble members (60 years each) of the Whole Atmospheric Community Climate Model version 4 performed for the Chemistry Climate Model Initiative, and also use reanalysis and satellite data for validation purposes. The composite evolution of ozone displays positive mixing ratio anomalies up to 0.5–0.6 ppmv above 550 K (~ 50 hPa) around the central warming date and negative anomalies below (−0.2 to −0.3 ppmv), consistently in observations, reanalysis and model. Our analysis shows a clear temporal offset between ozone eddy transport and diffusive ozone fluxes. The initial changes in ozone are mainly driven by isentropic eddy fluxes linked to enhanced wave drag responsible for the SSW. The recovery of climatological values in the aftermath of SSWs is slower in the lower than in the upper stratosphere, and is driven by the competing effects of cross-isentropic motions (which work towards the recovery) and isentropic irreversible mixing (which delays the recovery). These features are enhanced in strength and duration during sufficiently deep SSWs, particularly those followed by Polar-night Jet Oscillation (PJO) events. It is found that SSW-induced ozone concentration anomalies below 600 K (~ 40 hPa), as well as total column estimates, persist around one month longer in PJO than in non-PJO warmings.

Download Full-text

Enhanced transport and mixing of Arctic ozone during SSWs

10.5194/egusphere-egu2020-5899 ◽

2020 ◽

Author(s):

Alvaro de la Camara ◽

Marta Abalos ◽

Peter Hitchcock ◽

Natalia Calvo ◽

Rolando Garcia

Keyword(s):

Climate Model ◽

Wave Drag ◽

Advective Transport ◽

Mixing Properties ◽

Eddy Transport ◽

Eddy Fluxes ◽

Stratospheric Circulation ◽

Transport And Mixing ◽

Jet Oscillation ◽

Temporal Offset

The extreme disruptions of the wintertime stratospheric circulation during sudden stratospheric warmings (SSW) have important effects on tracer concentrations through alterations in transport and mixing properties. In this presentation we will examine the dynamics that control changes of Arctic ozone during the life cycle of SSWs, providing a quantitative analysis of both advective transport and mixing of Arctic ozone. We use output from four ensemble members (60 years each) of the Whole Atmospheric Community Climate Model, and also use reanalysis and satellite data for validation purposes. The composite evolution of ozone displays positive mixing ratio anomalies up to 0.5 &#8211; 0.6 ppmv above 550 K (&#8764;50 hPa) around the central warming date and negative anomalies below (-0.2 to -0.3 ppmv), consistently in observations, reanalysis and model.Our analysis shows a clear temporal offset between ozone eddy transport and diffusive ozone fluxes. The initial changes in ozone are mainly driven by isentropic eddy fluxes linked to enhanced wave drag responsible for the SSW. The recovery of climatological values in the aftermath of SSWs is slower in the lower than in the upper stratosphere, and is driven by the competing effects of cross-isentropic motions (which work towards the recovery) and isentropic mixing (which delays the recovery). These features are enhanced in strength and duration during sufficiently deep SSWs, particularly those also labeled as Polar-night Jet Oscillation (PJO) events. It is found that SSW-induced ozone concentration anomalies below 600 K (&#8764;40 hPa), as well as total column estimates, persist around one month longer in PJO than in non-PJO warmings.

Download Full-text

Multi-decadal Records of Stratospheric Composition and their Relationship to Stratospheric Circulation Change

10.5194/acp-2017-401 ◽

2017 ◽

Author(s):

Anne R. Douglass ◽

Susan E. Strahan ◽

Luke D. Oman ◽

Richard S. Stolarski

Keyword(s):

Transport Model ◽

Atmospheric Composition ◽

Model Driven ◽

Earth Observing System ◽

Circulation Change ◽

Decadal Scale ◽

Stratospheric Circulation ◽

Transport And Mixing ◽

Stratospheric Composition ◽

Modern Era

Abstract. Constituent evolution for 1990–2015 simulated using the Global Modeling Initiative Chemistry and Transport Model driven by meteorological fields from the Modern Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) is compared with three sources of observations: ground based column measurements of HNO3 and HCl from two stations in the Network for Detection of Atmospheric Composition Change (NDACCC, ~ 1990–ongoing); profiles of CH4 from the HALogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS, 1992–2005); profiles of N2O from the Microwave Limb Sounder on the Earth Observing System satellite Aura (2015–ongoing). The differences between observed and simulated values are shown to be time dependent, with better agreement after ~2000 compared with the prior decade. Furthermore, the differences between observed and simulated HNO3 and HCl columns are shown to be correlated with each other, suggesting that issues with the simulated transport and mixing cause the differences during the 1990s and these issues are less important during the later years. Because the simulated fields are related to mean age in the lower stratosphere, we use these comparisons to evaluate the time dependence of mean age. We use these relationships to account for dynamical variability when determining decadal scale trends in constituents and mean age. The ongoing NDACC column observations provide critical information necessary to substantiate trends in mean age obtained using fields from MERRA-2 or any other reanalysis products.

Download Full-text

Multi-decadal records of stratospheric composition and their relationship to stratospheric circulation change

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-12081-2017 ◽

2017 ◽

Vol 17 (19) ◽

pp. 12081-12096 ◽

Cited By ~ 5

Author(s):

Anne R. Douglass ◽

Susan E. Strahan ◽

Luke D. Oman ◽

Richard S. Stolarski

Keyword(s):

Transport Model ◽

Atmospheric Composition ◽

Global Modeling ◽

Model Driven ◽

Earth Observing System ◽

Circulation Change ◽

Stratospheric Circulation ◽

Transport And Mixing ◽

Stratospheric Composition ◽

Modern Era

Abstract. Constituent evolution for 1990–2015 simulated using the Global Modeling Initiative chemistry and transport model driven by meteorological fields from the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) is compared with three sources of observations: ground-based column measurements of HNO3 and HCl from two stations in the Network for the Detection of Atmospheric Composition Change (NDACC, ∼ 1990–ongoing), profiles of CH4 from the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS, 1992–2005), and profiles of N2O from the Microwave Limb Sounder on the Earth Observing System satellite Aura (2005–ongoing). The differences between observed and simulated values are shown to be time dependent, with better agreement after ∼ 2000 compared with the prior decade. Furthermore, the differences between observed and simulated HNO3 and HCl columns are shown to be correlated with each other, suggesting that issues with the simulated transport and mixing cause the differences during the 1990s and that these issues are less important during the later years. Because the simulated fields are related to mean age in the lower stratosphere, we use these comparisons to evaluate the time dependence of mean age. The ongoing NDACC column observations provide critical information necessary to substantiate trends in mean age obtained using fields from MERRA-2 or any other reanalysis products.

Download Full-text

Role of Mesoscale Eddies in Cross-Frontal Transport of Heat and Biogeochemical Tracers in the Southern Ocean

Journal of Physical Oceanography ◽

10.1175/jpo-d-14-0240.1 ◽

2015 ◽

Vol 45 (12) ◽

pp. 3057-3081 ◽

Cited By ~ 51

Author(s):

Carolina O. Dufour ◽

Stephen M. Griffies ◽

Gregory F. de Souza ◽

Ivy Frenger ◽

Adele K. Morrison ◽

...

Keyword(s):

Climate Model ◽

Mesoscale Eddies ◽

Ekman Layer ◽

Ekman Transport ◽

Depth Interval ◽

Diffusive Transport ◽

Advective Transport ◽

Total Transport ◽

Eddy Transport

AbstractThis study examines the role of processes transporting tracers across the Polar Front (PF) in the depth interval between the surface and major topographic sills, which this study refers to as the “PF core.” A preindustrial control simulation of an eddying climate model coupled to a biogeochemical model [GFDL Climate Model, version 2.6 (CM2.6)– simplified version of the Biogeochemistry with Light Iron Nutrients and Gas (miniBLING) 0.1° ocean model] is used to investigate the transport of heat, carbon, oxygen, and phosphate across the PF core, with a particular focus on the role of mesoscale eddies. The authors find that the total transport across the PF core results from a ubiquitous Ekman transport that drives the upwelled tracers to the north and a localized opposing eddy transport that induces tracer leakages to the south at major topographic obstacles. In the Ekman layer, the southward eddy transport only partially compensates the northward Ekman transport, while below the Ekman layer, the southward eddy transport dominates the total transport but remains much smaller in magnitude than the near-surface northward transport. Most of the southward branch of the total transport is achieved below the PF core, mainly through geostrophic currents. This study finds that the eddy-diffusive transport reinforces the southward eddy-advective transport for carbon and heat, and opposes it for oxygen and phosphate. Eddy-advective transport is likely to be the leading-order component of eddy-induced transport for all four tracers. However, eddy-diffusive transport may provide a significant contribution to the southward eddy heat transport due to strong along-isopycnal temperature gradients.

Download Full-text

Twenty-First Century Trends in Mixing Barriers and Eddy Transport in the Lower Stratosphere

10.5194/egusphere-egu21-2678 ◽

2021 ◽

Author(s):

Marta Abalos ◽

Alvaro de la Cámara

Keyword(s):

Lower Stratosphere ◽

Climate Model ◽

Substantial Reduction ◽

Polar Vortex ◽

Effective Diffusivity ◽

Wave Drag ◽

First Century ◽

Austral Spring ◽

Eddy Transport ◽

Climate Model Simulations

Future trends in isentropic mixing in the lower stratosphere remain largely unexplored, in contrast with the advective component of the Brewer-Dobson circulation. This study examines trends in effective diffusivity (&#954;eff ), a measure of the potential of the flow to produce isentropic mixing, in recent chemistry-climate model simulations. The results highlight substantial reduction of &#954;eff&#160; in the upper flanks of the subtropical jets from fall to spring, which are strengthened in response to greenhouse gas increases. This contrasts with stronger eddy transport, associated with increased wave drag in the region, peaking in summer near the critical lines. The projected ozone recovery leads to enhanced &#954;eff in polar austral spring and summer, associated with a weaker and shorter-lived austral polar vortex by the end of the 21st century.

Download Full-text

The Diurnal Variation in Stratospheric Ozone from MACC Reanalysis, ERA-Interim, WACCM, and Earth Observation Data: Characteristics and Intercomparison

Atmosphere ◽

10.3390/atmos12050625 ◽

2021 ◽

Vol 12 (5) ◽

pp. 625

Author(s):

Ansgar Schanz ◽

Klemens Hocke ◽

Niklaus Kämpfer ◽

Simon Chabrillat ◽

Antje Inness ◽

...

Keyword(s):

Diurnal Variation ◽

Climate Model ◽

Stratospheric Ozone ◽

Polar Vortex ◽

Model Systems ◽

Atmospheric Composition ◽

The Arctic ◽

Observation Data ◽

High Latitudes ◽

Free Running

In this study, we compare the diurnal variation in stratospheric ozone of the MACC (Monitoring Atmospheric Composition and Climate) reanalysis, ECMWF Reanalysis Interim (ERA-Interim), and the free-running WACCM (Whole Atmosphere Community Climate Model). The diurnal variation of stratospheric ozone results from photochemical and dynamical processes depending on altitude, latitude, and season. MACC reanalysis and WACCM use similar chemistry modules and calculate a similar diurnal cycle in ozone when it is caused by a photochemical variation. The results of the two model systems are confirmed by observations of the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) experiment and three selected sites of the Network for Detection of Atmospheric Composition Change (NDACC) at Mauna Loa, Hawaii (tropics), Bern, Switzerland (midlatitudes), and Ny-Ålesund, Svalbard (high latitudes). On the other hand, the ozone product of ERA-Interim shows considerably less diurnal variation due to photochemical variations. The global maxima of diurnal variation occur at high latitudes in summer, e.g., near the Arctic NDACC site at Ny-Ålesund, Svalbard. The local OZORAM radiometer observes this effect in good agreement with MACC reanalysis and WACCM. The sensed diurnal variation at Ny-Ålesund is up to 8% (0.4 ppmv) due to photochemical variations in summer and negligible during the dynamically dominated winter. However, when dynamics play a major role for the diurnal ozone variation as in the lower stratosphere (100–20 hPa), the reanalysis models ERA-Interim and MACC which assimilate data from radiosondes and satellites outperform the free-running WACCM. Such a domain is the Antarctic polar winter where a surprising novel feature of diurnal variation is indicated by MACC reanalysis and ERA-Interim at the edge of the polar vortex. This effect accounts for up to 8% (0.4 ppmv) in both model systems. In summary, MACC reanalysis provides a global description of the diurnal variation of stratospheric ozone caused by dynamics and photochemical variations. This is of high interest for ozone trend analysis and other research which is based on merged satellite data or measurements at different local time.

Download Full-text

Compensation between Resolved Wave Driving and Parameterized Orographic Gravity Wave Driving of the Brewer–Dobson Circulation and Its Response to Climate Change

Journal of Climate ◽

10.1175/jcli-d-13-00644.1 ◽

2014 ◽

Vol 27 (14) ◽

pp. 5601-5610 ◽

Cited By ~ 23

Author(s):

Michael Sigmond ◽

Theodore G. Shepherd

Keyword(s):

Climate Change ◽

Gravity Wave ◽

Northern Hemisphere ◽

Rossby Wave ◽

Climate Model ◽

Wave Drag ◽

High Latitudes ◽

Remarkable Degree ◽

The Impact

Abstract Following recent findings, the interaction between resolved (Rossby) wave drag and parameterized orographic gravity wave drag (OGWD) is investigated, in terms of their driving of the Brewer–Dobson circulation (BDC), in a comprehensive climate model. To this end, the parameter that effectively determines the strength of OGWD in present-day and doubled CO2 simulations is varied. The authors focus on the Northern Hemisphere during winter when the largest response of the BDC to climate change is predicted to occur. It is found that increases in OGWD are to a remarkable degree compensated by a reduction in midlatitude resolved wave drag, thereby reducing the impact of changes in OGWD on the BDC. This compensation is also found for the response to climate change: changes in the OGWD contribution to the BDC response to climate change are compensated by opposite changes in the resolved wave drag contribution to the BDC response to climate change, thereby reducing the impact of changes in OGWD on the BDC response to climate change. By contrast, compensation does not occur at northern high latitudes, where resolved wave driving and the associated downwelling increase with increasing OGWD, both for the present-day climate and the response to climate change. These findings raise confidence in the credibility of climate model projections of the strengthened BDC.

Download Full-text

Unprecedented strength of Hadley circulation in 2015–2016 impacts on CO2 interhemispheric difference

10.5194/acp-2018-203 ◽

2018 ◽

Author(s):

Jorgen S. Frederiksen ◽

Roger J. Francey

Keyword(s):

Global Warming ◽

Hadley Circulation ◽

Co2 Concentration ◽

Transport Processes ◽

Boreal Summer ◽

Boreal Winter ◽

Advective Transport ◽

Interhemispheric Difference ◽

Eddy Transport ◽

The Difference

Abstract. The extreme El Niño of 2015 and 2016 coincided with record global warming and unprecedented strength of the Hadley circulation with significant impact on mean interhemispheric (IH) transport of CO2 and on the difference in CO2 concentration between Mauna Loa and Cape Grim (Cmlo-cgo). The relative roles of eddy transport and mean advective transport on IH CO2 annual differences from 1992 through to 2016 is explored. Eddy transport processes occur mainly in boreal winter-spring when Cmlo-cgo is large; an important component is due to Rossby wave generation by the Himalayas and propagation through the equatorial Pacific westerly duct generating and transmitting turbulent kinetic energy. Mean transport occurs mainly in boreal summer-autumn and varies with the strength of the Hadley circulation. The timing of annual changes in Cmlo-cgo is found to coincide well with dynamical indices that we introduce to characterize the transports. During the unrivalled 2009–2010 step in Cmlo-cgo indices of eddy and mean transport reinforce. In contrast for the 2015 to 2016 change in Cmlo-cgo the mean transport counteracts the eddy transport and the record strength of the Hadley circulation determines the annual IH CO2 difference. The interaction of increasing global warming and extreme El Niños may have important implications for altering the balance between eddy and mean IH CO2 transfer.

Download Full-text

Quantifying tracer transport in the tropical lower stratosphere using WACCM

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-13245-2013 ◽

2013 ◽

Vol 13 (5) ◽

pp. 13245-13283 ◽

Cited By ~ 3

Author(s):

M. Abalos ◽

W. J. Randel ◽

D. E. Kinnison ◽

E. Serrano

Keyword(s):

Lower Stratosphere ◽

Climate Model ◽

Latitudinal Gradients ◽

Explicit Calculation ◽

Boreal Summer ◽

Tracer Transport ◽

Annual Cycles ◽

Tropical Tropopause ◽

Eddy Transport ◽

Isentropic Coordinates

Abstract. The zonal mean transport of ozone and carbon monoxide (CO) near the tropical tropopause is investigated using the Whole-Atmosphere Community Climate Model version 4 (WACCM4). The variability in temperature, ozone and CO in the model shows good agreement with satellite and balloon observations. Modeled temperature and tracers exhibit large and closely coupled annual cycles in the tropical lower stratosphere, as in the observations. The thermodynamic and tracer budgets in the model are analyzed based on the Transformed Eulerian Mean (TEM) framework on log-pressure coordinates and also using the isentropic formulation. Results show that the coupled seasonal cycles are mainly forced by tropical upwelling over altitudes with large vertical tracer gradients, in agreement with previous observational studies. The model also allows explicit calculation of eddy transport terms, which make an important contribution to ozone tendencies in the tropical lower stratosphere. The character of the eddy fluxes changes with altitude. At higher levels (~2 km above the cold point tropopause), isentropic eddy transport occurs during winter and spring in each hemisphere in the sub-tropics, associated with transient Rossby waves acting on strong background latitudinal gradients. At lower altitudes, close to the tropical tropopause, there is a maximum in horizontal eddy transport during boreal summer associated with the Asian monsoon anticyclone. Sub-seasonal variability in ozone and CO, tied to fluctuations in temperature, is primarily driven by transient tropical upwelling. In isentropic coordinates, the overall tracer budgets are similar to the log-pressure results, highlighting cross-isentropic mean advection as the main term in the balance. However, in isentropic coordinates the tracer variability is largely reduced on both seasonal and sub-seasonal timescales, because the tracer and temperature fluctuations are highly correlated (as a response to upwelling).

Download Full-text

Response of Arctic ozone to sudden stratospheric warmings