Short-period planetary waves in the Antarctic middle atmosphere

abstract Behavior of P, S and ScS residuals as well as those of differential travel times of ScS-P from the Jeffreys-Bullen tables are analyzed. The phases have been read from short-period records of the Antarctic station, Dumont d'Urville (DRV); the earthquakes originating in New Hebrides, Fiji-Tonga, and Banda Sea regions. P residuals from all regions show a mean value of about −1 sec. On the contrary, S and ScS residuals, well correlated among themselves, show important regional as well as focal-depth dependence. ScS-P residuals from shallow and intermediate shocks are largely positive for New Hebrides and largely negative for Banda Sea; those from intermediate shocks are moderately positive for Fiji-Tonga. The anomalies disappear at depths greater than about 200 km. Upper mantle shear velocity models are presented for the three regions. The models are discussed in relation to a sinking lithosphere.

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Observation of Kelvin–Helmholtz instabilities and gravity waves in the summer mesopause above Andenes in Northern Norway

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-6721-2018 ◽

2018 ◽

Vol 18 (9) ◽

pp. 6721-6732 ◽

Cited By ~ 9

Author(s):

Gunter Stober ◽

Svenja Sommer ◽

Carsten Schult ◽

Ralph Latteck ◽

Jorge L. Chau

Keyword(s):

Gravity Waves ◽

Middle Atmosphere ◽

Phase Speed ◽

Velocity Measurements ◽

Wind Variability ◽

Short Period ◽

Strong Shear ◽

Summer Echoes ◽

Period Wave ◽

Horizontal Wavelength

Abstract. We present observations obtained with the Middle Atmosphere Alomar Radar System (MAARSY) to investigate short-period wave-like features using polar mesospheric summer echoes (PMSEs) as a tracer for the neutral dynamics. We conducted a multibeam experiment including 67 different beam directions during a 9-day campaign in June 2013. We identified two Kelvin–Helmholtz instability (KHI) events from the signal morphology of PMSE. The MAARSY observations are complemented by collocated meteor radar wind data to determine the mesoscale gravity wave activity and the vertical structure of the wind field above the PMSE. The KHIs occurred in a strong shear flow with Richardson numbers Ri < 0.25. In addition, we observed 15 wave-like events in our MAARSY multibeam observations applying a sophisticated decomposition of the radial velocity measurements using volume velocity processing. We retrieved the horizontal wavelength, intrinsic frequency, propagation direction, and phase speed from the horizontally resolved wind variability for 15 events. These events showed horizontal wavelengths between 20 and 40 km, vertical wavelengths between 5 and 10 km, and rather high intrinsic phase speeds between 45 and 85 m s−1 with intrinsic periods of 5–10 min.

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Stratospheric temperatures and tracer transport in a nudged 4-year middle atmosphere GCM simulation

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-5-961-2005 ◽

2005 ◽

Vol 5 (1) ◽

pp. 961-1006 ◽

Cited By ~ 2

Author(s):

M. K. van Aalst ◽

J. Lelieveld ◽

B. Steil ◽

C. Brühl ◽

P. Jöckel ◽

...

Keyword(s):

Interannual Variability ◽

General Circulation ◽

Middle Atmosphere ◽

Circulation Model ◽

Detailed Comparison ◽

The Arctic ◽

Cold Bias ◽

Tracer Transport ◽

Quasi Biennial Oscillation ◽

The Antarctic

Abstract. We have performed a 4-year simulation with the Middle Atmosphere General Circulation Model MAECHAM5/MESSy, while slightly nudging the model’s meteorology in the free troposphere (below 113 hPa) towards ECMWF analyses. We show that the nudging 5 technique, which leaves the middle atmosphere almost entirely free, enables comparisons with synoptic observations. The model successfully reproduces many specific features of the interannual variability, including details of the Antarctic vortex structure. In the Arctic, the model captures general features of the interannual variability, but falls short in reproducing the timing of sudden stratospheric warmings. A 10 detailed comparison of the nudged model simulations with ECMWF data shows that the model simulates realistic stratospheric temperature distributions and variabilities, including the temperature minima in the Antarctic vortex. Some small (a few K) model biases were also identified, including a summer cold bias at both poles, and a general cold bias in the lower stratosphere, most pronounced in midlatitudes. A comparison 15 of tracer distributions with HALOE observations shows that the model successfully reproduces specific aspects of the instantaneous circulation. The main tracer transport deficiencies occur in the polar lowermost stratosphere. These are related to the tropopause altitude as well as the tracer advection scheme and model resolution. The additional nudging of equatorial zonal winds, forcing the quasi-biennial oscillation, sig20 nificantly improves stratospheric temperatures and tracer distributions.

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Observations and Modeling of Increased Nitric Oxide in the Antarctic Polar Middle Atmosphere Associated With Geomagnetic Storm-Driven Energetic Electron Precipitation

Journal of Geophysical Research Space Physics ◽

10.1029/2018ja025507 ◽

2018 ◽

Vol 123 (7) ◽

pp. 6009-6025 ◽

Cited By ~ 9

Author(s):

D. A. Newnham ◽

M. A. Clilverd ◽

C. J. Rodger ◽

K. Hendrickx ◽

L. Megner ◽

...

Keyword(s):

Nitric Oxide ◽

Geomagnetic Storm ◽

Middle Atmosphere ◽

Energetic Electron ◽

Electron Precipitation ◽

The Antarctic

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Unusual Changes in the Antarctic Middle Atmosphere During the 2019 Warming in the Southern Hemisphere

Geophysical Research Letters ◽

10.1029/2020gl089199 ◽

2020 ◽

Vol 47 (19) ◽

Author(s):

S. Eswaraiah ◽

Jeong‐Han Kim ◽

Wonseok Lee ◽

Junyoung Hwang ◽

Kondapalli Niranjan Kumar ◽

...

Keyword(s):

Southern Hemisphere ◽

Middle Atmosphere ◽

The Antarctic

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Arctic tidal characteristics at Eureka (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006/07: seasonal and longitudinal variations, migrating and non-migrating tides

Annales Geophysicae ◽

10.5194/angeo-27-1153-2009 ◽

2009 ◽

Vol 27 (3) ◽

pp. 1153-1173 ◽

Cited By ~ 29

Author(s):

A. H. Manson ◽

C. E. Meek ◽

T. Chshyolkova ◽

X. Xu ◽

T. Aso ◽

...

Keyword(s):

High Arctic ◽

Early Summer ◽

Planetary Waves ◽

Diurnal Tide ◽

The Arctic ◽

Meteor Radar ◽

Atmospheric Propagation ◽

Wave Numbers ◽

The Antarctic ◽

Abstract Operation

Abstract. Operation of a Meteor Radar at Eureka, Ellesmere Island (80° N, 86° W) began in February 2006. The first 12 months of wind data (82–97 km) are combined with winds from the Adventdalen, Svalbard Island (78° N, 16° E) Meteor Radar to provide the first contemporaneous longitudinally spaced observations of mean winds, tides and planetary waves at such high Arctic latitudes. Unique polar information on diurnal non-migrating tides (NMT) is provided, as well as complementary information to that existing for the Antarctic on the semidiurnal NMT. Zonal and meridional monthly mean winds differed significantly between Canada and Norway, indicating the influence of stationary planetary waves (SPW) in the Arctic mesopause region. Both diurnal (D) and semi-diurnal (SD) winds also demonstrated significantly different magnitudes at Eureka and Svalbard. Typically the D tide was larger at Eureka and the SD tide was larger at Svalbard. Tidal amplitudes in the Arctic were also generally larger than expected from extrapolation of high mid-latitude data. For example time-sequences from ~90 km showed D wind oscillations at Eureka of 30 m/s in February–March, and four day bursts of SD winds at Svalbard reached 40 m/s in June 2006. Fitting of wave numbers for the migrating and non-migrating tides (MT, NMT) successfully determines dominant tides for each month and height. For the diurnal tide, NMT with s=0, +2 (westward) dominate in non-summer months, while for the semi-diurnal tide NMT with s=+1, +3 occur most often during equinoctial or early summer months. These wave numbers are consistent with stationary planetary wave (SPW)-tidal interactions. Assessment of the global topographic forcing and atmospheric propagation of the SPW (S=1, 2) suggests these winter waves of the Northern Hemisphere are associated with the 78–80° N diurnal NMT, but that the SPW of the Southern Hemisphere winter have little influence on the summer Arctic tidal fields. In contrast the large SPW and NMT of the Arctic winter may be associated, consistent with Antarctic observations, with the observed occurrence of the semidiurnal NMT in the Antarctic summer.

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Nighttime Mesospheric Ozone During the 2002 Southern Hemispheric Major Stratospheric Warming

10.5194/acp-2016-758 ◽

2016 ◽

Author(s):

Christine Smith-Johnsen ◽

Yvan Orsolini ◽

Frode Stordal ◽

Varavut Limpasuvan ◽

Kristell Pérot

Keyword(s):

Atomic Oxygen ◽

Lower Stratosphere ◽

Climate Model ◽

Middle Atmosphere ◽

Ozone Layer ◽

Stratospheric Warming ◽

Mesospheric Ozone ◽

Northern Hemispheric ◽

Second Year ◽

The Antarctic

Abstract. A Sudden Stratospheric Warming (SSW) affects the chemistry and dynamics of the middle atmosphere. The major warmings occur roughly every second year in the Northern Hemispheric (NH) winter, but has only been observed once in the Southern Hemisphere (SH), during the Antarctic winter of 2002. Using the National Center for Atmospheric Research's (NCAR) Whole Atmosphere Community Climate Model with specified dynamics (WACCM-SD), this study investigates the effects of this rare warming event on the ozone layer located around the SH mesopause. This secondary ozone layer changes with respect to hydrogen, oxygen, temperature, and the altered SH polar circulation during the major SSW. The 2002 SH winter was characterized by three zonal-mean zonal wind reductions in the upper stratosphere before a fourth wind reversal reaches the lower stratosphere, marking the onset of the major SSW. At the time of these four wind reversals, a corresponding episodic increase can be seen in the modeled nighttime ozone concentration in the secondary ozone layer. Observations by the Global Ozone Monitoring by Occultation of Stars (GOMOS, an instrument on board the satellite Envisat) demonstrate similar ozone enhancement as in the model. This ozone increase is attributable largely to enhanced upwelling and the associated cooling of the altitude region in conjunction with the wind reversal. Unlike its NH counterpart, the secondary ozone layer during the SH major SSW appeared to be impacted more by the effects of atomic oxygen than hydrogen.

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Anomalous quasi-stationary planetary waves over the Antarctic region in 1988 and 2002

Annales Geophysicae ◽

10.5194/angeo-26-1101-2008 ◽

2008 ◽

Vol 26 (5) ◽

pp. 1101-1108 ◽

Cited By ~ 11

Author(s):

A. V. Grytsai ◽

O. M. Evtushevsky ◽

G. P. Milinevsky

Keyword(s):

Lower Stratosphere ◽

Polar Vortex ◽

Amplitude Distribution ◽

Stationary Wave ◽

Planetary Waves ◽

Late Winter ◽

Stratospheric Polar Vortex ◽

Latitudinal Position ◽

The Antarctic ◽

Peak Value

Abstract. Anomalies in the Antarctic total ozone and amplitudes of the quasi-stationary planetary waves in the lower stratosphere temperature during the winter and spring of 1988 and 2002 have been compared. Westward displacement of the quasi-stationary wave (QSW) extremes by 50°–70° relative to the preceding years of the strong stratospheric polar vortex in 1987 and 2001, respectively, was observed. A dependence of the quasi-stationary wave ridge and trough positions on the strength of the westerly zonal wind in the lower stratosphere is shown. Comparison of the QSW amplitude in the lower stratosphere temperature in July and August shows that the amplitude distribution with latitude in August could be considered as a possible indication of the future anomalous warming in Antarctic spring. In August 2002, the QSW amplitude of 10 K at the edge region of the polar vortex (60° S–65° S) preceded the major warming in September, whereas in August 1988, the highest 7 K amplitude at 55° S preceded the large warming in the next months. These results suggest that the peak value of the lower stratosphere temperature QSW amplitude and the peak latitudinal position in late winter can influence the southern polar vortex strength in spring.

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