4 research outputs found
Response of Arctic ozone to sudden stratospheric warmings
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.</p
Response of Arctic ozone to sudden stratospheric warmings
International audienceSudden 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
Response of Arctic ozone to sudden stratospheric warmings
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 (similar to 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 (similar to 40 hPa), as well as total column estimates, persist around 1 month longer in PJO than in non-PJO warmings