Upper stratosphere‐mesosphere‐lower thermosphere perturbations during the formation of the Arctic polar night jet in 2019‐2020

2021 ◽  
Author(s):  
Renata Lukianova ◽  
Alexander Kozlovsky ◽  
Mark Lester
Keyword(s):  
Lower Thermosphere ◽  
The Arctic ◽  
Polar Night

scholarly journals The wintertime two-day wave in the polar stratosphere, mesosphere and lower thermosphere

2008 ◽  
Vol 8 (3) ◽  
pp. 749-755 ◽  
Author(s):  
D. J. Sandford ◽  
M. J. Schwartz ◽  
N. J. Mitchell
Keyword(s):  
Lower Thermosphere ◽  
Radar Data ◽  
The Arctic ◽  
Horizontal Wind ◽  
Meteor Radar ◽  
Polar Night ◽  
Zonal Wavenumber ◽  
Mesosphere And Lower Thermosphere ◽  
Polar Stratosphere ◽  
Striking Contrast

Abstract. Recent observations of the polar mesosphere have revealed that waves with periods near two days reach significant amplitudes in both summer and winter. This is in striking contrast to mid-latitude observations where two-day waves maximise in summer only. Here, we use data from a meteor radar at Esrange (68° N, 21° E) in the Arctic and data from the MLS instrument aboard the EOS Aura satellite to investigate the wintertime polar two-day wave in the stratosphere, mesosphere and lower thermosphere. The radar data reveal that mesospheric two-day wave activity measured by horizontal-wind variance has a semi-annual cycle with maxima in winter and summer and equinoctial minima. The MLS data reveal that the summertime wave in the mesosphere is dominated by a westward-travelling zonal wavenumber three wave with significant westward wavenumber four present. It reaches largest amplitudes at mid-latitudes in the southern hemisphere. In the winter polar mesosphere, however, the wave appears to be an eastward-travelling zonal wavenumber two, which is not seen during the summer. At the latitude of Esrange, the eastward-two wave reaches maximum amplitudes near the stratopause and appears related to similar waves previously observed in the polar stratosphere. We conclude that the wintertime polar two-day wave is the mesospheric manifestation of an eastward-propagating, zonal-wavenumber-two wave originating in the stratosphere, maximising at the stratopause and likely to be generated by instabilities in the polar night jet.

scholarly journals The wintertime two-day wave in the Polar Stratosphere, Mesosphere and lower Thermosphere

2007 ◽  
Vol 7 (5) ◽  
pp. 14747-14765
Author(s):  
D. J. Sandford ◽  
M. J. Schwartz ◽  
N. J. Mitchell
Keyword(s):  
Lower Thermosphere ◽  
Radar Data ◽  
The Arctic ◽  
Horizontal Wind ◽  
Meteor Radar ◽  
Polar Night ◽  
Zonal Wavenumber ◽  
Mesosphere And Lower Thermosphere ◽  
Polar Stratosphere ◽  
Striking Contrast

Abstract. Recent observations of the polar mesosphere have revealed that waves with periods near two days reach significant amplitudes in both summer and winter. This is in striking contrast to mid-latitude observations where two-day waves maximise in summer only. Here, we use data from a meteor radar at Esrange (68° N, 21° E) in the Arctic and data from the MLS instrument aboard the EOS Aura satellite to investigate the wintertime polar two-day wave in the stratosphere, mesosphere and lower thermosphere. The radar data reveal that mesospheric two-day wave activity measured by horizontal-wind variance has a semi-annual cycle with maxima in winter and summer and equinoctial minima. The MLS data reveal that the summertime wave in the mesosphere is dominated by a westward-travelling zonal wavenumber three wave with significant westward wavenumber four present. It reaches largest amplitudes at mid-latitudes in the southern hemisphere. In the winter polar mesosphere, however, the wave appears to be an eastward-travelling zonal wavenumber two, which is not seen during the summer. At the latitude of Esrange, the eastward-two wave reaches maximum amplitudes near the stratopause and appears related to similar waves previously observed in the polar stratosphere. We conclude that the wintertime polar two-day wave is the mesospheric manifestation of an eastward-propagating, zonal-wavenumber-two wave originating in the stratosphere, maximising at the stratopause and likely to be generated by instabilities in the polar night jet.

scholarly journals Horizontally resolved structures of radar backscatter from polar mesospheric layers

2012 ◽  
Vol 10 ◽  
pp. 285-290 ◽  
Author(s):  
R. Latteck ◽  
W. Singer ◽  
M. Rapp ◽  
T. Renkwitz ◽  
G. Stober
Keyword(s):  
Middle Atmosphere ◽  
Beam Steering ◽  
Lower Thermosphere ◽  
The Arctic ◽  
Phased Array Antenna ◽  
Vhf Radar ◽  
The North ◽  
Expansion Stage ◽  
Arctic Atmosphere ◽  
High Flexibility

Abstract. The Leibniz-Institute of Atmospheric Physics in Kühlungsborn, Germany (IAP) installed a new powerful VHF radar on the North-Norwegian island Andøya (69.30° N, 16.04° E) from 2009 to 2011. The new Middle Atmosphere Alomar Radar System (MAARSY) replaces the existing ALWIN radar which has been in continuous operation on Andøya for more than 10 yr. MAARSY is a monostatic radar operated at 53.5 MHz with an active phased array antenna consisting of 433 Yagi antennas each connected to its own transceiver with independent control of frequency, phase and power of the transmitted signal. This arrangement provides a very high flexibility of beam forming and beam steering. It allows classical beam swinging operation as well as experiments with simultaneous multiple beams and the use of modern interferometric applications for improved studies of the Arctic atmosphere from the troposphere up to the lower thermosphere with high spatial-temporal resolution. The installation of the antenna was completed in August 2009. An initial expansion stage of 196 transceiver modules was installed in spring 2010, upgraded to 343 transceiver modules in December 2010 and the installation of the radar was completed in spring 2011. Beside standard observations of tropospheric winds and Polar Mesosphere Summer Echoes, multi-beam experiments using up to 91 beams quasi-simultaneously in the mesosphere have been carried out using the different expansion stages of the system during campaigns in 2010 and 2011. These results provided a first insight into the horizontal variability of Polar Mesosphere Summer and Winter Echoes in an area of about 80 km by 80 km with time resolutions between 3 and 9 min.

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 Cormorants dive through the Polar night

2005 ◽  
Vol 1 (4) ◽  
pp. 469-471 ◽  
Author(s):  
David Grémillet ◽  
Grégoire Kuntz ◽  
Caroline Gilbert ◽  
Antony J Woakes ◽  
Patrick J Butler ◽  
...  
Keyword(s):  
Visual Cues ◽  
Significant Proportion ◽  
Dive Depth ◽  
Day Length ◽  
The Arctic ◽  
High Latitudes ◽  
Phalacrocorax Carbo ◽  
Polar Night ◽  
Light Levels ◽  
Great Cormorants

Most seabirds are visual hunters and are thus strongly affected by light levels. Dependence on vision should be problematic for species wintering at high latitudes, as they face very low light levels for extended periods during the Polar night. We examined the foraging rhythms of male great cormorants ( Phalacrocorax carbo ) wintering north of the Polar circle in West Greenland, conducting the first year-round recordings of the diving activity in a seabird wintering at high latitudes. Dive depth data revealed that birds dived every day during the Arctic winter and did not adjust their foraging rhythms to varying day length. Therefore, a significant proportion of the dive bouts were conducted in the dark (less than 1 lux) during the Polar night. Our study underlines the stunning adaptability of great cormorants and raises questions about the capacity of diving birds to use non-visual cues to target fish.

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