scholarly journals On the observation of mesospheric air inside the arctic stratospheric polar vortex in early 2003

2005 ◽  
Vol 5 (4) ◽  
pp. 7457-7496 ◽  
Author(s):  
A. Engel ◽  
T. Möbius ◽  
H.-P. Haase ◽  
H. Bönisch ◽  
T. Wetter ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Michelson Interferometer ◽  
Polar Vortex ◽  
The Arctic ◽  
Stratospheric Polar Vortex ◽  
Air Masses ◽  
Model Study ◽  
Tuneable Diode Laser ◽  
Ftir Spectrometer ◽  
The Difference

Abstract. During several balloon flights inside the Arctic polar vortex in early 2003, unusual trace gas distributions were observed, which indicate a strong influence of mesospheric air in the stratosphere. The tuneable diode laser (TDL) instrument SPIRALE (Spectroscopie InFrarouge par Absorption de Lasers Embarqués) measured unusually high CO values (up to 600 ppb) on 27 January at about 30 km altitude. The cryosampler BONBON sampled air masses with very high molecular Hydrogen, extremely low SF6 and enhanced CO values on 6 March at about 25 km altitude. Finally, the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) Fourier Transform Infra-Red (FTIR) spectrometer showed NOy values which are significantly higher than NOy* (the NOy derived from a correlation between N2O and NOy under undisturbed conditions), on 21 and 22 March in a layer centred at 22 km altitude. Thus, the mesospheric air seems to have been present in a layer descending from about 30 km in late January to 25 km altitude in early March and about 22 km altitude on 20 March. We present corroborating evidence from a model study using the KASIMA (KArlsruhe Simulation model of the Middle Atmosphere) model that also shows a layer of mesospheric air, which descended into the stratosphere in November and early December 2002, before the minor warming which occurred in late December 2002 lead to a descent of upper stratospheric air, cutting of a layer in which mesospheric air is present. This layer then descended inside the vortex over the course of the winter. The same feature is found in trajectory calculations, based on a large number of trajectories started in the vicinity of the observations on 6 March. Based on the difference between the mean age derived from SF6 (which has an irreversible mesospheric loss) and from CO2 (whose mesospheric loss is much smaller and reversible) we estimate that the fraction of mesospheric air in the layer observed on 6 March, must have been somewhere between 35% and 100%.

scholarly journals Observation of mesospheric air inside the arctic stratospheric polar vortex in early 2003

2006 ◽  
Vol 6 (1) ◽  
pp. 267-282 ◽  
Author(s):  
A. Engel ◽  
T. Möbius ◽  
H.-P. Haase ◽  
H. Bönisch ◽  
T. Wetter ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Michelson Interferometer ◽  
Polar Vortex ◽  
The Arctic ◽  
Stratospheric Polar Vortex ◽  
Air Masses ◽  
Model Study ◽  
Tuneable Diode Laser ◽  
Ftir Spectrometer ◽  
The Difference

Abstract. During several balloon flights inside the Arctic polar vortex in early 2003, unusual trace gas distributions were observed, which indicate a strong influence of mesospheric air in the stratosphere. The tuneable diode laser (TDL) instrument SPIRALE (Spectroscopie Infra-Rouge par Absorption de Lasers Embarqués) measured unusually high CO values (up to 600 ppb) on 27 January at about 30 km altitude. The cryosampler BONBON sampled air masses with very high molecular Hydrogen, extremely low SF6 and enhanced CO values on 6 March at about 25 km altitude. Finally, the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) Fourier Transform Infra-Red (FTIR) spectrometer showed NOy values which are significantly higher than NOy* (the NOy derived from a correlation between N2O and NOy under undisturbed conditions), on 21 and 22 March in a layer centred at 22 km altitude. Thus, the mesospheric air seems to have been present in a layer descending from about 30 km in late January to 25 km altitude in early March and about 22 km altitude on 20 March. We present corroborating evidence from a model study using the KASIMA (KArlsruhe SImulation model of the Middle Atmosphere) model that also shows a layer of mesospheric air, which descended into the stratosphere in November and early December 2002, before the minor warming which occurred in late December 2002 lead to a descent of upper stratospheric air, cutting off a layer in which mesospheric air is present. This layer then descended inside the vortex over the course of the winter. The same feature is found in trajectory calculations, based on a large number of trajectories started in the vicinity of the observations on 6 March. Based on the difference between the mean age derived from SF6 (which has an irreversible mesospheric loss) and from CO2 (whose mesospheric loss is much smaller and reversible) we estimate that the fraction of mesospheric air in the layer observed on 6 March, must have been somewhere between 35% and 100%.

scholarly journals Statistical Characterization of Arctic Polar-Night Jet Oscillation Events

2013 ◽  
Vol 26 (6) ◽  
pp. 2096-2116 ◽  
Author(s):  
Peter Hitchcock ◽  
Theodore G. Shepherd ◽  
Gloria L. Manney
Keyword(s):  
Time Scale ◽  
Middle Atmosphere ◽  
Polar Vortex ◽  
Extended Period ◽  
The Arctic ◽  
Polar Night ◽  
Stratospheric Polar Vortex ◽  
Statistical Characterization ◽  
Long Time ◽  
Jet Oscillation

Abstract A novel diagnostic tool is presented, based on polar-cap temperature anomalies, for visualizing daily variability of the Arctic stratospheric polar vortex over multiple decades. This visualization illustrates the ubiquity of extended-time-scale recoveries from stratospheric sudden warmings, termed here polar-night jet oscillation (PJO) events. These are characterized by an anomalously warm polar lower stratosphere that persists for several months. Following the initial warming, a cold anomaly forms in the middle stratosphere, as does an anomalously high stratopause, both of which descend while the lower-stratospheric anomaly persists. These events are characterized in four datasets: Microwave Limb Sounder (MLS) temperature observations; the 40-yr ECMWF Re-Analysis (ERA-40) and Modern Era Retrospective Analysis for Research and Applications (MERRA) reanalyses; and an ensemble of three 150-yr simulations from the Canadian Middle Atmosphere Model. The statistics of PJO events in the model are found to agree very closely with those of the observations and reanalyses. The time scale for the recovery of the polar vortex following sudden warmings correlates strongly with the depth to which the warming initially descends. PJO events occur following roughly half of all major sudden warmings and are associated with an extended period of suppressed wave-activity fluxes entering the polar vortex. They follow vortex splits more frequently than they do vortex displacements. They are also related to weak vortex events as identified by the northern annular mode; in particular, those weak vortex events followed by a PJO event show a stronger tropospheric response. The long time scales, predominantly radiative dynamics, and tropospheric influence of PJO events suggest that they represent an important source of conditional skill in seasonal forecasting.

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 Zonal wave numbers 1-5 in planetary waves from the TOMS total ozone at 65° S

2005 ◽  
Vol 23 (5) ◽  
pp. 1565-1573 ◽  
Author(s):  
A. Grytsai ◽  
Z. Grytsai ◽  
A. Evtushevsky ◽  
G. Milinevsky ◽  
N. Leonov
Keyword(s):  
Total Ozone ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Polar Vortex ◽  
Planetary Waves ◽  
Wave Number ◽  
Stratospheric Polar Vortex ◽  
Term Change ◽  
Wave Numbers ◽  
The Difference

Abstract. Planetary waves in the total ozone at the southern latitude of 65° S are studied to obtain the main characteristics of the zonal wave numbers 1–5. The TOMS total ozone data were used to analyze the amplitude and periodicity variations of the five spectral components during August-December of 1979–2003. A presence of the shorter period of waves 1–3 in 1996 (7 days) in comparison with 2002 (8–12 days) is revealed which can be attributed to the distinction in conditions of typical and anomalously weak stratospheric polar vortex, probably, a strong and weak mean zonal wind. The interannual variations of the monthly and 5-month mean amplitudes of the zonal wave numbers 1–5 are described. Wave 1 has the largest amplitude in October (up to 139 DU in 2000) and increasing amplitude trend (15 DU/decade for October 1979–2003). The 5-month mean amplitudes averaged over 1979–2003 are 53.6, 29.9, 15.5, 10.5, and 7.8 DU for the wave number sequence 1, 2, 3, 4 and 5, respectively. For the stationary components the amplitudes are 38.3, 4.8, 1.8, 1.2, 0.7 DU, respectively. Thus, the stationary component of wave 1 and the traveling one of waves 2–5 are predominant. The tendencies in a long-term change in the wave number amplitude can be explained by taking into account the degree of wave deformation of the stratospheric polar vortex edge, net meridional displacements of the lower stratosphere air, and the difference between the total ozone loss and negative trends in the polar and mid-latitude regions. Keywords. General circulation – Middle atmosphere dynamics – Waves and tides

scholarly journals Correlations of mesospheric winds with subtle motion of the Arctic polar vortex

2010 ◽  
Vol 10 (2) ◽  
pp. 431-436 ◽  
Author(s):  
Y. Bhattacharya ◽  
A. J. Gerrard
Keyword(s):  
Michelson Interferometer ◽  
Polar Vortex ◽  
High Arctic ◽  
The Arctic ◽  
Stratospheric Polar Vortex ◽  
Mesopause Region ◽  
Neutral Winds ◽  
Wind Speeds ◽  
Initial Location ◽  
The Relationship

Abstract. This paper investigates the relationship between high latitude upper mesospheric winds and the state of the stratospheric polar vortex in the absence of major sudden stratospheric warmings. A ground based Michelson Interferometer stationed at Resolute Bay (74°43' N, 94°58' W) in the Canadian High Arctic is used to measure mesopause region neutral winds using the hydroxyl (OH) Meinel-band airglow emission (central altitude of ~85 km). These observed winds are compared to analysis winds in the upper stratosphere during November and December of 1995 and 1996; years characterized as cold, stable polar vortex periods. Correlation of mesopause wind speeds with those from the upper stratosphere is found to be significant for the 1996 season when the polar vortex is subtly displaced off its initial location by a strong Aleutian High. These mesopause winds are observed to lead stratospheric winds by approximately two days with increasing (decreasing) mesospheric winds predictive of decreasing (increasing) stratospheric winds. No statistically significant correlations are found for the 1995 season when there is no such displacement of the polar vortex.

scholarly journals Correlations of mesospheric winds with subtle motion of the Arctic polar vortex

2009 ◽  
Vol 9 (4) ◽  
pp. 16549-16562 ◽  
Author(s):  
Y. Bhattacharya ◽  
A. J. Gerrard
Keyword(s):  
Michelson Interferometer ◽  
Polar Vortex ◽  
High Arctic ◽  
The Arctic ◽  
Stratospheric Polar Vortex ◽  
Mesopause Region ◽  
Neutral Winds ◽  
Wind Speeds ◽  
Initial Location ◽  
The Relationship

Abstract. This paper investigates the relationship between high latitude upper mesospheric winds and the state of the stratospheric polar vortex in the absence of major sudden stratospheric warmings. A ground based Michelson Interferometer stationed at Resolute Bay (74°43´ N, 94°58´ W) in the Canadian High Arctic is used to measure mesopause region neutral winds using the hydroxyl (OH) Meinel-band airglow emission (central altitude of ~85 km). These observed winds are compared to analysis winds in the upper stratosphere during November and December of 1995 and 1996; years characterized as cold, stable polar vortex periods. Correlation of mesopause wind speeds with those from the upper stratosphere is found to be significant for the 1996 season when the polar vortex is subtly displaced off its initial location by a strong Aleutian High. These mesopause winds are observed to lead stratospheric winds by approximately two days with increasing (decreasing) mesospheric winds predictive of decreasing (increasing) stratospheric winds. No statistically significant correlations are found for the 1995 season when there is no such displacement of the polar vortex.

scholarly journals Quantifying Asymmetric Wave Breaking and Two-Way Transport

2004 ◽  
Vol 61 (22) ◽  
pp. 2735-2748 ◽  
Author(s):  
Noboru Nakamura
Keyword(s):  
Wave Breaking ◽  
Polar Vortex ◽  
Effective Diffusivity ◽  
The Other ◽  
Stratospheric Polar Vortex ◽  
Air Masses ◽  
Rossby Wave Breaking ◽  
Advection Diffusion Equation ◽  
Extratropical Tropopause ◽  
Asymmetric Wave

Abstract Effective diffusivity calculated from a scalar field that obeys the advection–diffusion equation has proved useful for estimating the permeability of unsteady boundaries of air masses such as the edge of the stratospheric polar vortex and the extratropical tropopause. However, the method does not discriminate the direction of transport—whereas some material crosses the boundary from one side to the other, some material does so in the other direction—yet the extant method concerns only the net transport. In this paper, the diagnostic is extended to allow partitioning of fluxes of mass and tracer into opposing directions. This is accomplished by discriminating the regions of “inward” and “outward” wave breaking with the local curvature of the tracer field. The utility of the new method is demonstrated for nonlinear Kelvin– Helmholtz instability and Rossby wave breaking in the stratosphere using a numerically generated tracer. The method successfully quantifies two-way transport and hence the direction of wave breaking—the predominantly equatorward breaking of Rossby waves in the extratropical middle stratosphere, for example. Isolated episodes of mixing are identified well, particularly by the mass flux that primarily arises from the tracer filaments. Comparison of different transport schemes suggests that the results are reasonably robust under a varying subgrid representation of the model.

scholarly journals Investigation of Arctic middle-atmospheric dynamics using 3 years of H<sub>2</sub>O and O<sub>3</sub> measurements from microwave radiometers at Ny-Ålesund

2019 ◽  
Author(s):  
Franziska Schranz ◽  
Brigitte Tschanz ◽  
Rolf Rüfenacht ◽  
Klemens Hocke ◽  
Mathias Palm ◽  
...  
Keyword(s):  
Water Vapour ◽  
Middle Atmosphere ◽  
Microwave Radiometer ◽  
Polar Vortex ◽  
The Arctic ◽  
High Time Resolution ◽  
Middle Atmospheric Dynamics ◽  
Wind Profiles ◽  
Microwave Radiometers

Abstract. We use 3 years of water vapour and ozone measurements to analyse dynamical events in the polar middle atmosphere such as sudden stratospheric warmings (SSW), polar vortex shifts, water vapour descent rates and periodicities. The measurements were performed with the two ground-based microwave radiometers MIAWARA-C and GROMOS-C which are co-located at the AWIPEV research base at Ny-Ålesund, Svalbard (79° N, 12° E) since September 2015. The almost continuous datasets of water vapour and ozone are characterised by a high time resolution in the order of hours. A thorough intercomparison of these datasets with models and measurements from satellite, ground-based and in-situ instruments was performed. In the upper stratosphere and lower mesosphere the MIAWARA-C profiles agree within 5 % with SD-WACCM simulations and ACE-FTS measurements whereas AuraMLS measurements show an average offset of 10–15 % depending on altitude but constant in time. Stratospheric GROMOS-C profiles are within 5 % of the satellite instruments AuraMLS and ACE-FTS and the ground-based microwave radiometer OZORAM which is also located at Ny-Ålesund. During these first three years of the measurement campaign typical phenomena of the Arctic middle atmosphere took place and we analysed their signatures in the water vapour and ozone datasets. Inside of the polar vortex in autumn we found the descent rate of mesospheric water vapour to be 435 m/day on average. In early 2017 distinct increases in mesospheric water vapour of about 2 ppm were observed when the polar vortex was displaced and midlatitude air was brought to Ny-Ålesund. Two major sudden stratospheric warmings took place in March 2016 and February 2018 where ozone enhancements of up to 4 ppm were observed. The zonal wind reversals accompanying a major SSW were captured in the GROMOS-C wind profiles which are retrieved from the ozone spectra. After the SSW in February 2018 the polar vortex re-established and the water vapour descent rate in the mesosphere was 355 m/day. In the water vapour and ozone time series signatures of atmospheric waves with periods close to 2, 5, 10 and 16 days were found.

scholarly journals Seasonal Prediction Skill of Northern Extratropical Surface Temperature Driven by the Stratosphere

2017 ◽  
Vol 30 (12) ◽  
pp. 4463-4475 ◽  
Author(s):  
Liwei Jia ◽  
Xiaosong Yang ◽  
Gabriel Vecchi ◽  
Richard Gudgel ◽  
Thomas Delworth ◽  
...  
Keyword(s):  
Climate Model ◽  
Lower Troposphere ◽  
Polar Vortex ◽  
Seasonal Prediction ◽  
The Arctic ◽  
Northern Eurasia ◽  
Stratospheric Polar Vortex ◽  
Near Surface ◽  
Predictive Skill

This study explores the role of the stratosphere as a source of seasonal predictability of surface climate over Northern Hemisphere extratropics both in the observations and climate model predictions. A suite of numerical experiments, including climate simulations and retrospective forecasts, are set up to isolate the role of the stratosphere in seasonal predictive skill of extratropical near-surface land temperature. It is shown that most of the lead-0-month spring predictive skill of land temperature over extratropics, particularly over northern Eurasia, stems from stratospheric initialization. It is further revealed that this predictive skill of extratropical land temperature arises from skillful prediction of the Arctic Oscillation (AO). The dynamical connection between the stratosphere and troposphere is also demonstrated by the significant correlation between the stratospheric polar vortex and sea level pressure anomalies, as well as the migration of the stratospheric zonal wind anomalies to the lower troposphere.

Improvement in Prediction of the Arctic Oscillation with a Realistic Ocean Initial Condition in a CGCM

2015 ◽  
Vol 28 (22) ◽  
pp. 8951-8967 ◽  
Author(s):  
Hae-Jeong Kim ◽  
Joong-Bae Ahn
Keyword(s):  
Arctic Oscillation ◽  
Polar Vortex ◽  
Polar Front ◽  
Forecast Skill ◽  
Sea Surface ◽  
The Arctic ◽  
Initial Condition ◽  
Stratospheric Polar Vortex ◽  
The Arctic Oscillation ◽  
Polar Front Jet

Abstract This study verifies the impact of improved ocean initial conditions on the Arctic Oscillation (AO) forecast skill by assessing the one-month lead predictability of boreal winter AO using the Pusan National University (PNU) coupled general circulation model (CGCM). Hindcast experiments were performed on two versions of the model, one does not use assimilated ocean initial data (V1.0) and one does (V1.1), and the results were comparatively analyzed. The forecast skill of V1.1 was superior to that of V1.0 in terms of the correlation coefficient between the predicted and observed AO indices. In the regression analysis, V1.1 showed more realistic spatial similarities than V1.0 did in predicted sea surface temperature and atmospheric circulation fields. The authors suggest the relative importance of the contribution of the ocean initial condition to the AO forecast skill was because the ocean data assimilation increased the predictability of the AO, to some extent, through the improved interaction between tropical forcing induced by realistic sea surface temperature (SST) and atmospheric circulation. In V1.1, as in the observation, the cold equatorial Pacific SST anomalies generated the weakened tropical convection and Hadley circulation over the Pacific, resulting in a decelerated subtropical jet and accelerated polar front jet in the extratropics. The intensified polar front jet implies a stronger stratospheric polar vortex relevant to the positive AO phase; hence, surface manifestations of the reflected positive AO phase were then induced through the downward propagation of the stratospheric polar vortex. The results suggest that properly assimilated initial ocean conditions might contribute to improve the predictability of global oscillations, such as the AO, through large-scale tropical ocean–atmosphere interaction.

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