scholarly journals Observations of filamentary structures near the vortex edge in the Arctic winter lower stratosphere

2013 ◽  
Vol 13 (21) ◽  
pp. 10859-10871 ◽  
Author(s):  
C. Kalicinsky ◽  
J.-U. Grooß ◽  
G. Günther ◽  
J. Ungermann ◽  
J. Blank ◽  
...  
Keyword(s):  
Cross Sections ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Lagrangian Model ◽  
The Arctic ◽  
Small Scale ◽  
Air Mass ◽  
Mixing Ratios ◽  
Passive Tracers

Abstract. The CRISTA-NF (Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers) instrument is an airborne infrared limb sounder operated aboard the Russian research aircraft M55-Geophysica. The instrument successfully participated in a large Arctic aircraft campaign within the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) project in Kiruna (Sweden) from January to March 2010. This paper concentrates on the measurements taken during one flight of the campaign, which took place on 2 March in the vicinity of the polar vortex. We present two-dimensional cross-sections of derived volume mixing ratios for the trace gases CFC-11, O3, and ClONO2 with an unprecedented vertical resolution of about 500 to 600 m for a large part of the observed altitude range (≈ 6–19 km) and a dense horizontal sampling along flight direction of ≈ 15 km. The trace gas distributions show several structures, for example a part of the polar vortex and a vortex filament, which can be identified by means of O3–CFC-11 tracer–tracer correlations. The observations made during this flight are interpreted using the chemistry and transport model CLaMS (Chemical Lagrangian Model of the Stratosphere). Comparisons of the observations with the model results are used to assess the performance of the model with respect to advection, mixing, and the chemistry in the polar vortex. These comparisons confirm the capability of CLaMS to reproduce even very small-scale structures in the atmosphere, which partly have a vertical extent of only 1 km. Based on the good agreement between simulation and observation, we use artificial (passive) tracers, which represent different air mass origins (e.g. vortex, tropics), to further analyse the CRISTA-NF observations in terms of the composition of air mass origins. These passive tracers clearly illustrate the observation of filamentary structures that include tropical air masses. A characteristic of the Arctic winter 2009/10 was a sudden stratospheric warming in December that led to a split of the polar vortex. The vortex re-established at the end of December. Our passive tracer simulations suggest that large parts of the re-established vortex consisted to about 45% of high- and mid-latitude air.

scholarly journals Small-scale transport structures in the Arctic winter 2009/2010

2013 ◽  
Vol 13 (4) ◽  
pp. 10463-10498 ◽  
Author(s):  
C. Kalicinsky ◽  
J.-U. Grooß ◽  
G. Günther ◽  
J. Ungermann ◽  
J. Blank ◽  
...  
Keyword(s):  
Cross Sections ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Lagrangian Model ◽  
The Arctic ◽  
Small Scale ◽  
Model Concept ◽  
Mixing Ratios ◽  
Flight Direction

Abstract. The CRISTA-NF (Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers) instrument is an airborne infrared limb sounder operated aboard the Russian research aircraft M55-Geophysica. The instrument successfully participated in a large Arctic aircraft campaign within the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) project from January to March 2010 in Kiruna, Sweden. This paper concentrates on the measurements during one flight of the campaign, which took place on 2 March in the vicinity of the polar vortex. We present two-dimensional cross-sections of volume mixing ratios for the trace gases CFC-11, O3, and ClONO2 with an unprecedented vertical resolution of about 500 to 600 m for a large part of the observed altitude range and a dense horizontal sampling along flight direction of ≈ 15 km. The trace gas distributions show several structures like the polar vortex and filaments composed of air masses of different origin. The situation during the analysed flight is simulated by the chemistry and transport model CLaMS (Chemical Lagrangian Model of the Stratosphere) and compared with the measurements to assess the performance of the model with respect to advection, mixing, and the chemistry in the polar vortex. These comparisons confirm the capability of CLaMS to reproduce even very small-scale structures in the atmosphere. Based on the good agreement between simulation and observation, we use a model concept utilising artificial tracers to further analyse the CRISTA-NF observations in terms of air mass origin. A characteristic of the Arctic winter 2009/10 was a sudden stratospheric warming in early December that led to a split of the polar vortex. The vortex re-established at the end of December. Our passive tracer simulations suggest that large parts of the re-established vortex consisted to about 45% of high- and mid-latitude air.

scholarly journals Nitrification of the lowermost stratosphere during the exceptionally cold Arctic winter 2015–2016

2019 ◽  
Vol 19 (21) ◽  
pp. 13681-13699 ◽  
Author(s):  
Marleen Braun ◽  
Jens-Uwe Grooß ◽  
Wolfgang Woiwode ◽  
Sören Johansson ◽  
Michael Höpfner ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Cross Sections ◽  
Large Scale ◽  
Potential Temperature ◽  
Lagrangian Model ◽  
The Arctic ◽  
Small Scale ◽  
Mixing Ratios ◽  
Fine Structures ◽  
The Impact

Abstract. The Arctic winter 2015–2016 was characterized by exceptionally low stratospheric temperatures, favouring the formation of polar stratospheric clouds (PSCs) from mid-December until the end of February down to low stratospheric altitudes. Observations by GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) on HALO (High Altitude and LOng range research aircraft) during the PGS (POLSTRACC–GW-LCYCLE II–SALSA) campaign from December 2015 to March 2016 allow the investigation of the influence of denitrification on the lowermost stratosphere (LMS) with a high spatial resolution. Two-dimensional vertical cross sections of nitric acid (HNO3) along the flight track and tracer–tracer correlations derived from the GLORIA observations document detailed pictures of wide-spread nitrification of the Arctic LMS during the course of an entire winter. GLORIA observations show large-scale structures and local fine structures with enhanced absolute HNO3 volume mixing ratios reaching up to 11 ppbv at altitudes of 13 km in January and nitrified filaments persisting until the middle of March. Narrow coherent structures tilted with altitude of enhanced HNO3, observed in mid-January, are interpreted as regions recently nitrified by sublimating HNO3-containing particles. Overall, extensive nitrification of the LMS between 5.0 and 7.0 ppbv at potential temperature levels between 350 and 380 K is estimated. The GLORIA observations are compared with CLaMS (Chemical Lagrangian Model of the Stratosphere) simulations. The fundamental structures observed by GLORIA are well reproduced, but differences in the fine structures are diagnosed. Further, CLaMS predominantly underestimates the spatial extent of HNO3 maxima derived from the GLORIA observations as well as the overall nitrification of the LMS. Sensitivity simulations with CLaMS including (i) enhanced sedimentation rates in case of ice supersaturation (to resemble ice nucleation on nitric acid trihydrate (NAT)), (ii) a global temperature offset, (iii) modified growth rates (to resemble aspherical particles with larger surfaces) and (iv) temperature fluctuations (to resemble the impact of small-scale mountain waves) slightly improved the agreement with the GLORIA observations of individual flights. However, no parameter could be isolated which resulted in a general improvement for all flights. Still, the sensitivity simulations suggest that details of particle microphysics play a significant role for simulated LMS nitrification in January, while air subsidence, transport and mixing become increasingly important for the simulated HNO3 distributions towards the end of the winter.

scholarly journals Nitrification of the lowermost stratosphere during the exceptionally cold Arctic winter 2015/16

2019 ◽  
Author(s):  
Marleen Braun ◽  
Jens-Uwe Grooß ◽  
Wolfgang Woiwode ◽  
Sören Johansson ◽  
Michael Höpfner ◽  
...  
Keyword(s):  
Cross Sections ◽  
Large Scale ◽  
Potential Temperature ◽  
Lagrangian Model ◽  
The Arctic ◽  
Small Scale ◽  
Mountain Waves ◽  
Mixing Ratios ◽  
Fine Structures ◽  
The Impact

Abstract. The Arctic winter 2015/16 was characterized by exceptionally cold stratospheric temperatures, favouring the formation of polar stratospheric clouds (PSCs) from mid-December until the end of February down to low stratospheric altitudes. Observations by GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) on HALO (High Altitude and LOng range research aircraft) during the PGS (POLSTRACC/GW-LCYLCE II/SALSA) campaign from December 2015 to March 2016 allow an investigation of the influence of denitrification on the lowermost stratosphere (LMS) with a high spatial resolution. For the first time vertical cross-sections of nitric acid (HNO3) along the flight track and tracer-tracer correlations derived from the GLORIA observations document detailed pictures of wide-spread nitrification of the Arctic LMS during the course of an entire winter. GLORIA observations show large-scale structures and local fine structures with strongly enhanced absolute HNO3 volume mixing ratios reaching up to 11 ppbv at altitudes of 11 km in January and nitrified filaments persisting until the middle of March. Narrow streaks of enhanced HNO3, observed in mid-January, are interpreted as regions recently nitrified by sublimating HNO3-containing particles. Overall, a nitrification of the LMS between 5.0 ppbv and 7.0 ppbv at potential temperature levels between 350 and 380 K is estimated. This extent of nitrification has never been observed before in the Arctic lowermost stratosphere. The GLORIA observations are compared with CLaMS (Chemical Lagrangian Model of the Stratosphere) simulations. The fundamental structures observed by GLORIA are well reproduced, but differences in the fine structures are diagnosed. Further, CLaMS predominantly underestimates the spatial extent of maximum HNO3 mixing ratios derived from the GLORIA observations as well as the enhancement at lower altitudes. Sensitivity simulations with CLaMS including (i) enhanced sedimentation rates in case of ice supersaturation (to resemble ice nucleation on NAT), (ii) a global temperature offset, (iii) modified growth rates (to resemble aspherical particles with larger surfaces) and (iv) temperature fluctuations (to resemble the impact of small-scale mountain waves) mostly improve the agreement with the GLORIA observations. The sensitivity simulations suggest that details of particle microphysics play a significant role for simulated LMS nitrification in January, while air subsidence, transport and mixing become increasingly important towards the end of the winter.

scholarly journals Influence of transport and mixing in autumn on stratospheric ozone variability over the Arctic in early winter

2012 ◽  
Vol 12 (17) ◽  
pp. 7921-7930
Author(s):  
D. Blessmann ◽  
I. Wohltmann ◽  
M. Rex
Keyword(s):  
Transport Model ◽  
Stratospheric Ozone ◽  
Vortex Formation ◽  
Polar Vortex ◽  
The Arctic ◽  
Early Winter ◽  
Mixing Ratios ◽  
Ozone Amount ◽  
High Fraction ◽  
Transport And Mixing

Abstract. Early winter ozone mixing ratios in the Arctic middle stratosphere show an interannual variability of about 10%. We show that ozone variability in early January is caused by dynamical processes during Arctic polar vortex formation in autumn (September to December). Observational data from satellites and ozone sondes are used in conjunction with simulations of the chemistry and transport model ATLAS to examine the relationship between the meridional and vertical origin of air enclosed in the polar vortex and its ozone amount. For this, we use a set of artificial model tracers to deduce the origin of the air masses in the vortex in January in latitude and altitude in September. High vortex mean ozone mixing ratios are correlated with a high fraction of air from low latitudes enclosed in the vortex and a high fraction of air that experienced small net subsidence (in a Lagrangian sense). As a measure for the strength of the Brewer-Dobson circulation and meridional mixing in autumn, we use the Eliassen-Palm flux through the mid-latitude tropopause averaged from September to November. In the lower stratosphere, this quantity correlates well with the origin of air enclosed in the vortex and reasonably well with the ozone amount in early winter.

scholarly journals Influence of transport and mixing in autumn on stratospheric ozone variability over the Arctic in early winter

2012 ◽  
Vol 12 (6) ◽  
pp. 15083-15113
Author(s):  
D. Blessmann ◽  
I. Wohltmann ◽  
M. Rex
Keyword(s):  
Transport Model ◽  
Stratospheric Ozone ◽  
Vortex Formation ◽  
Polar Vortex ◽  
The Arctic ◽  
Early Winter ◽  
Mixing Ratios ◽  
Ozone Amount ◽  
High Fraction ◽  
Transport And Mixing

Abstract. Early winter ozone mixing ratios in the Arctic middle stratosphere show a fair amount of interannual variability. We show that ozone variability in early January is caused by dynamical processes during Arctic polar vortex formation in autumn (September to December). Observational data from satellites and ozone sondes are used in conjunction with simulations of the Chemistry and Transport Model ATLAS to examine the relationship between the meridional and vertical origin of air enclosed in the polar vortex and its ozone amount. For this, we use a set of artificial model tracers to deduce the origin of the air masses in the vortex in January in latitude and altitude in September. High vortex mean ozone mixing ratios are related to a high fraction of air from low latitudes enclosed in the vortex and a high fraction of air that experienced small net subsidence. As a measure for the strength of the Brewer-Dobson circulation and meridional mixing in autumn, we use the Eliassen-Palm flux through the mid-latitude tropopause averaged from August to November. In the lower stratosphere, this quantity correlates well with both the ozone amount in early winter and the origin of air enclosed in the vortex.

Record springtime stratospheric ozone depletion at 80°N in 2020

2021 ◽  
Author(s):  
Ramina Alwarda ◽  
Kristof Bognar ◽  
Kimberly Strong ◽  
Martyn Chipperfield ◽  
Sandip Dhomse ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
The Arctic ◽  
Optical Absorption Spectroscopy ◽  
Chemical Transport Model ◽  
Polar Stratospheric Clouds ◽  
Ozone Loss ◽  
Stratospheric Clouds

<p>The Arctic winter of 2019-2020 was characterized by an unusually persistent polar vortex and temperatures in the lower stratosphere that were consistently below the threshold for the formation of polar stratospheric clouds (PSCs). These conditions led to ozone loss that is comparable to the Antarctic ozone hole. Ground-based measurements from a suite of instruments at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Canada (80.05°N, 86.42°W) were used to investigate chemical ozone depletion. The vortex was located above Eureka longer than in any previous year in the 20-year dataset and lidar measurements provided evidence of polar stratospheric clouds (PSCs) above Eureka. Additionally, UV-visible zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements showed record ozone loss in the 20-year dataset, evidence of denitrification along with the slowest increase of NO<sub>2</sub> during spring, as well as enhanced reactive halogen species (OClO and BrO). Complementary measurements of HCl and ClONO<sub>2</sub> (chlorine reservoir species) from a Fourier transform infrared (FTIR) spectrometer showed unusually low columns that were comparable to 2011, the previous year with significant chemical ozone depletion. Record low values of HNO<sub>3</sub> in the FTIR dataset are in accordance with the evidence of PSCs and a denitrified atmosphere. Estimates of chemical ozone loss were derived using passive ozone from the SLIMCAT offline chemical transport model to account for dynamical contributions to the stratospheric ozone budget.</p>

scholarly journals Middle atmospheric water vapour and dynamics in the vicinity of the polar vortex during the Hygrosonde-2 campaign

2009 ◽  
Vol 9 (13) ◽  
pp. 4407-4417 ◽  
Author(s):  
S. Lossow ◽  
M. Khaplanov ◽  
J. Gumbel ◽  
J. Stegman ◽  
G. Witt ◽  
...  
Keyword(s):  
Water Vapour ◽  
Middle Atmosphere ◽  
Polar Vortex ◽  
The Arctic ◽  
Small Scale ◽  
Air Masses ◽  
Mixing Ratios ◽  
Water Vapour Concentration ◽  
Wind Shears

Abstract. The Hygrosonde-2 campaign took place on 16 December 2001 at Esrange/Sweden (68° N, 21° E) with the aim to investigate the small scale distribution of water vapour in the middle atmosphere in the vicinity of the Arctic polar vortex. In situ balloon and rocket-borne measurements of water vapour were performed by means of OH fluorescence hygrometry. The combined measurements yielded a high resolution water vapour profile up to an altitude of 75 km. Using the characteristic of water vapour being a dynamical tracer it was possible to directly relate the water vapour data to the location of the polar vortex edge, which separates air masses of different character inside and outside the polar vortex. The measurements probed extra-vortex air in the altitude range between 45 km and 60 km and vortex air elsewhere. Transitions between vortex and extra-vortex usually coincided with wind shears caused by gravity waves which advect air masses with different water vapour volume mixing ratios. From the combination of the results from the Hygrosonde-2 campaign and the first flight of the optical hygrometer in 1994 (Hygrosonde-1) a clear picture of the characteristic water vapour distribution inside and outside the polar vortex can be drawn. Systematic differences in the water vapour concentration between the inside and outside of the polar vortex can be observed all the way up into the mesosphere. It is also evident that in situ measurements with high spatial resolution are needed to fully account for the small-scale exchange processes in the polar winter middle atmosphere.

scholarly journals A Match-based approach to the estimation of polar stratospheric ozone loss using Aura Microwave Limb Sounder observations

2015 ◽  
Vol 15 (17) ◽  
pp. 9945-9963 ◽  
Author(s):  
N. J. Livesey ◽  
M. L. Santee ◽  
G. L. Manney
Keyword(s):  
Stratospheric Ozone ◽  
Potential Temperature ◽  
Polar Vortex ◽  
Rate Of Change ◽  
The Arctic ◽  
Air Mass ◽  
Ozone Loss ◽  
Chemical Destruction ◽  
Induced Changes ◽  
The Impact

Abstract. The well-established "Match" approach to quantifying chemical destruction of ozone in the polar lower stratosphere is applied to ozone observations from the Microwave Limb Sounder (MLS) on NASA's Aura spacecraft. Quantification of ozone loss requires distinguishing transport- and chemically induced changes in ozone abundance. This is accomplished in the Match approach by examining cases where trajectories indicate that the same air mass has been observed on multiple occasions. The method was pioneered using ozonesonde observations, for which hundreds of matched ozone observations per winter are typically available. The dense coverage of the MLS measurements, particularly at polar latitudes, allows matches to be made to thousands of observations each day. This study is enabled by recently developed MLS Lagrangian trajectory diagnostic (LTD) support products. Sensitivity studies indicate that the largest influence on the ozone loss estimates are the value of potential vorticity (PV) used to define the edge of the polar vortex (within which matched observations must lie) and the degree to which the PV of an air mass is allowed to vary between matched observations. Applying Match calculations to MLS observations of nitrous oxide, a long-lived tracer whose expected rate of change is negligible on the weekly to monthly timescales considered here, enables quantification of the impact of transport errors on the Match-based ozone loss estimates. Our loss estimates are generally in agreement with previous estimates for selected Arctic winters, though indicating smaller losses than many other studies. Arctic ozone losses are greatest during the 2010/11 winter, as seen in prior studies, with 2.0 ppmv (parts per million by volume) loss estimated at 450 K potential temperature (~ 18 km altitude). As expected, Antarctic winter ozone losses are consistently greater than those for the Arctic, with less interannual variability (e.g., ranging between 2.3 and 3.0 ppmv at 450 K). This study exemplifies the insights into atmospheric processes that can be obtained by applying the Match methodology to a densely sampled observation record such as that from Aura MLS.

scholarly journals CRISTA-NF measurements with unprecedented vertical resolution during the RECONCILE aircraft campaign

2012 ◽  
Vol 5 (5) ◽  
pp. 1173-1191 ◽  
Author(s):  
J. Ungermann ◽  
C. Kalicinsky ◽  
F. Olschewski ◽  
P. Knieling ◽  
L. Hoffmann ◽  
...  
Keyword(s):  
Cross Sections ◽  
Polar Vortex ◽  
The Arctic ◽  
Trace Gas ◽  
Retrieval Algorithm ◽  
Vertical Resolution ◽  
Mixing Ratios ◽  
Flight Direction ◽  
Research Aircraft ◽  
Gas Volume

Abstract. The Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers (CRISTA-NF), an airborne infrared limb-sounder, was operated aboard the high-flying Russian research aircraft M55-Geophysica during the Arctic RECONCILE campaign from January to March 2010. This paper describes the calibration process of the instrument and the retrieval algorithm employed and then proceeds to present retrieved trace gas volume mixing ratio cross-sections for one specific flight in this campaign. We are able to resolve the uppermost troposphere/lower stratosphere for several trace gas species for several kilometres below the flight altitude (16 to 19 km) with an unprecedented vertical resolution of 400 to 500 m for the limb-sounding technique. The instrument points sideways with respect to the flight direction. Therefore, the observations are also characterised by a rather high horizontal sampling along the flight track, which provides a full vertical profile every ≈15 km. Assembling the vertical trace gas profiles derived from CRISTA-NF measurements to cross-sections shows filaments of vortex and extra-vortex air masses in the vicinity of the polar vortex. During this campaign, the M55-Geophysica carried further instruments enabling trace gas volume mixing ratios derived from CRISTA-NF to be validated by comparing them with measurements by the in situ instruments HAGAR and FOZAN and observations by MIPAS-STR. This validation suggests that the retrieved trace gas volume mixing ratios are both qualitatively and quantitatively reliable.

scholarly journals MIPAS-STR measurements in the Arctic UTLS in winter/spring 2010: instrument characterization, retrieval and validation

2012 ◽  
Vol 5 (6) ◽  
pp. 1205-1228 ◽  
Author(s):  
W. Woiwode ◽  
H. Oelhaf ◽  
T. Gulde ◽  
C. Piesch ◽  
G. Maucher ◽  
...  
Keyword(s):  
Cross Sections ◽  
Stratospheric Ozone ◽  
Trace Gases ◽  
Michelson Interferometer ◽  
Polar Vortex ◽  
The Arctic ◽  
Radiometric Calibration ◽  
Mid Infrared ◽  
Mean Differences

Abstract. The mid-infrared FTIR-limb-sounder Michelson Interferometer for Passive Atmospheric Sounding–STRatospheric aircraft (MIPAS-STR) was deployed onboard the research aircraft M55 Geophysica during the RECONCILE campaign (Reconciliation of Essential Process Parameters for an Enhanced Predictability of Arctic Stratospheric Ozone Loss and its Climate Interactions) in the Arctic winter/spring 2010. From the MIPAS-STR measurements, vertical profiles and 2-dimensional vertical cross-sections of temperature and trace gases are retrieved. Detailed mesoscale structures of polar vortex air, extra vortex air and vortex filaments are identified in the results at typical vertical resolutions of 1 to 2 km and typical horizontal sampling densities of 45 or 25 km, depending on the sampling programme. Results are shown for the RECONCILE flight 11 on 2 March 2010 and are validated with collocated in-situ measurements of temperature, O3, CFC-11, CFC-12 and H2O. Exceptional agreement is found for the in-situ comparisons of temperature and O3, with mean differences (vertical profile/along flight track) of 0.2/−0.2 K for temperature and −0.01/0.05 ppmv for O3 and corresponding sample standard deviations of the mean differences of 0.7/0.6 K and 0.1/0.3 ppmv. The comparison of the retrieved vertical cross-sections of HNO3 from MIPAS-STR and the infrared limb-sounder Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere–New Frontiers (CRISTA–NF) indicates a high degree of agreement. We discuss MIPAS-STR in its current configuration, the spectral and radiometric calibration of the measurements and the retrieval of atmospheric parameters from the spectra. The MIPAS-STR measurements are significantly affected by continuum-like contributions, which are attributed to background aerosol and broad spectral signatures from interfering trace gases, and are important for mid-infrared limb-sounding in the Upper Troposphere/Lower Stratosphere (UTLS) region. Taking into consideration continuum-like effects, we present a scheme suitable for accurate retrievals of temperature and an extended set of trace gases, including the correction of a systematic line-of-sight offset.

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