The 2009 stratospheric major warming described from synergistic use of BASCOE water vapour analyses and MLS observations

Lahoz, W. A.; Errera, Quentin; Viscardy, S.; Manney, G. L.

doi:10.5194/acp-11-4689-2011

Cited by 17 publications

(15 citation statements)

References 46 publications

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“…The polar vortex descent rate strongly increased around 25 January up to 15 K day −1 on 1000 K and only around 3 K day −1 on 500 K during the late January. The variability of polar vortex descent rate reported here is consistent with findings by Manney et al (2009b) and Lahoz et al (2011) where the tracer isopleths method based on MLS observations of N 2 O, CO and H 2 O was used. The onset of the heating rate anomalies at each altitude, and thus their downward propagation, is roughly synchronous with the temperature anomalies shown in Fig.…”

Section: Dynamical Backgroundsupporting

confidence: 80%

Impact of the 2009 major sudden stratospheric warming on the composition of the stratosphere

Tao¹,

Konopka²,

Ploeger³

et al. 2015

Atmos. Chem. Phys.

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Abstract. In a case study of a remarkable major sudden stratospheric warming (SSW) during the boreal winter 2008/09, we investigate how transport and mixing triggered by this event affected the composition of the entire stratosphere in the Northern Hemisphere. We simulate this event with the Chemical Lagrangian Model of the Stratosphere (CLaMS), both with optimized mixing parameters and with no mixing, i.e. with transport occurring only along the Lagrangian trajectories. The results are investigated by using tracer-tracer correlations and by applying the transformed Eulerian-mean formalism. The CLaMS simulation of N 2 O and O 3 , and in particular of the O 3 -N 2 O tracer correlations with optimized mixing parameters, shows good agreement with the Aura Microwave Limb Sounder (MLS) data. The spatial distribution of mixing intensity in CLaMS correlates fairly well with the Eliassen-Palm flux convergence. This correlation illustrates how planetary waves drive mixing. By comparing simulations with and without mixing, we find that after the SSW, poleward transport of air increases, not only across the vortex edge but also across the subtropical transport barrier. Moreover, the SSW event, at the same time, accelerates polar descent and tropical ascent of the BrewerDobson circulation. The accelerated ascent in the tropics and descent at high latitudes first occurs in the upper stratosphere and then propagates downward to the lower stratosphere. This downward propagation takes over 1 month from the potential temperature level of 1000 to 400 K.

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Section: Dynamical Backgroundsupporting

confidence: 80%

Impact of the 2009 major sudden stratospheric warming on the composition of the stratosphere

Tao¹,

Konopka²,

Ploeger³

et al. 2015

Atmos. Chem. Phys.

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“…The time period of January 2009 was chosen because of the dynamic activity that accompanied the unusually large 2009 Arctic stratospheric major warming (Manney et al, 2009;Lahoz et al, 2011). The winter stratosphere is generally a location with large horizontal ozone gradients, making wind extraction favorable, as explained in Sect.…”

Section: Methodsmentioning

confidence: 99%

Limitations of wind extraction from 4D-Var assimilation of ozone

et al. 2013

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Time-dependent variational data assimilation allows the possibility of extracting wind information from observations of ozone or other trace gases. Since trace gas observations are not available at sufficient resolution for deriving feature-track winds, they must be combined with model background information to produce an analysis. If done with time-dependent variational assimilation, wind information may be extracted via the adjoint of the linearized tracer continuity equation. This paper presents idealized experiments that illustrate the mechanics of tracer–wind extraction and demonstrate some of the limitations of this procedure. We first examine tracer–wind extraction using a simple one-dimensional advection equation. The analytic solution for a single trace gas observation is discussed along with numerical solutions for multiple observations. The limitations of tracer–wind extraction are then explored using highly idealized ozone experiments performed with a development version of the Navy Global Environmental Model (NAVGEM) in which globally distributed hourly stratospheric ozone profiles are assimilated in a single 6 h update cycle in January 2009. Starting with perfect background ozone conditions, but imperfect dynamical conditions, ozone errors develop over the 6 h background window. Wind increments are introduced in the analysis in order to reduce the differences between background ozone and ozone observations. For "perfect" observations (unbiased and no random error), this results in root-mean-square (RMS) vector wind error reductions of up to ~4 m s⁻¹ in the winter hemisphere and tropics. Wind extraction is more difficult in the summer hemisphere due to weak ozone gradients and smaller background wind errors. The limitations of wind extraction are also explored for observations with imposed random errors and for limited sampling patterns. As expected, the amount of wind information extracted degrades as observation errors or data voids increase. In the case of poorly specified observation error covariances, assimilation of ozone data with imposed errors may result in increased RMS wind error, since the assimilation is constrained too tightly to the noisy observations

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“… Randall et al [2006] showed that enhanced descent of NO x into the Arctic vortex occurred after the 2006 SSW, and Randall et al [2009]showed that such enhanced descent coincided with an elevated stratopause in 2006 as well as in other years. It was also shown using satellite observations from the Microwave Limb Sounder (MLS), the Atmospheric Chemistry Experiment ‐ Fourier Transform Spectrometer, and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument that there was strong descent of various species, including CO and N 2 O, following the reformation of the vortex in 2006 and 2009 [ Manney et al , 2008b, 2009a, 2009b; Lahoz et al , 2011]. Kvissel et al [2011] used WACCM to show this CO rich intrusion from the mesosphere into the middle stratosphere is well correlated with the reformation of the vortex in the lower mesosphere.…”

Section: Introductionmentioning

confidence: 99%

High Resolution Dynamics Limb Sounder observations of the gravity wave‐driven elevated stratopause in 2006

et al. 2012

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(HIRDLS), the Microwave Limb Sounder (MLS), and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite instruments are compared to illustrate the vertical range over which version 6 HIRDLS temperatures are scientifically useful. In order to determine the quality of HIRDLS temperatures in the middle atmosphere, we compare the height and temperature of the HIRDLS stratopause with MLS and SABER before, during, and after the 2006 major stratospheric sudden warming. Results show that HIRDLS observes the elevated stratopause at 78 km two days later than MLS and five days after SABER. We compare the geographical temperature structure of these data sets at 0.01 hPa during this period. Though HIRDLS temperatures are consistently 5-10 K lower in the mesosphere, this is the first study to show that the horizontal temperature distribution is in good spatial and temporal agreement with MLS and SABER up to $80 km. Gravity wave momentum flux and planetary wave 1 amplitudes are derived from HIRDLS and shown to be in agreement with previous studies. We use HIRDLS to show a $30 K increase in stratopause temperature following enhanced gravity wave momentum flux in the lower mesosphere.

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The 2009 stratospheric major warming described from synergistic use of BASCOE water vapour analyses and MLS observations

Cited by 17 publications

References 46 publications

Impact of the 2009 major sudden stratospheric warming on the composition of the stratosphere

Impact of the 2009 major sudden stratospheric warming on the composition of the stratosphere

Limitations of wind extraction from 4D-Var assimilation of ozone

High Resolution Dynamics Limb Sounder observations of the gravity wave‐driven elevated stratopause in 2006

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