First observations of Southern Hemisphere polar mesosphere winter echoes including conjugate occurrences at ∼69°S latitude

Morris, R. J.; Klekociuk, Andrew; Holdsworth, David A.

doi:10.1029/2010gl046298

Cited by 18 publications

(15 citation statements)

References 20 publications

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“…Later investigations confirmed this early proposal (e.g. Lübken et al, 2006Lübken et al, , 2007Rapp et al, 2011;Morris et al, 2011). However, measurements with lidar and radar (Kirkwood et al, 2002;Stebel et al, 2004;Belova et al, 2005;Kero et al, 2008;La Hoz and Havnes, 2008) have triggered the hypothesis that small charged aerosol particles (probably of meteoric origin) play a similar role as in the case of PMSE (e.g.…”

Section: Introductionsupporting

confidence: 49%

“…Czechowsky et al, 1979;Ecklund and Balsley, 1981;Collis et al, 1992;Belova et al, 2005;Zeller et al, 2006;Kirkwood, 2007;Lübken et al, 2007;Rapp et al, 2011;Morris et al, 2011). The occurrence rate of PMWE is positively correlated with the ionization level of the D-region.…”

Section: Introductionmentioning

confidence: 77%

“…8 to 13 November 2004, was also reported by Hall et al (2007) based on MF radar observations. It is further interesting to note that the Davis MST Radar in Antarctica (68.6 • S, 78.0 • E) also measured peak PMWE intensity on 11 November 2004 (Morris et al, 2011). That is, a very strong PMWE event was observed simultaneously in both hemispheres.…”

Section: Analysis Techniquementioning

confidence: 99%

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Statistical characteristics of PMWE observations by the EISCAT VHF radar

Strelnikova¹,

Rapp

2013

Ann. Geophys.

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In the present paper ~ 32.5 h of EISCAT VHF PMWE observations were analyzed with focus on spectral properties like spectral width, doppler shift and spectral shape. Examples from two days of observations with weak and strong polar mesosphere winter echo (PMWE) signals are presented and discussed in detail. These examples reveal a large variability from one case to the other. That is, some features like an observed change of vertical wind direction and spectral broadening can be very prominent in one case, but unnoticeable in the other case. However, for all observations a change of spectral shape inside the layer relative to the incoherent background is noticed

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Section: Introductionsupporting

confidence: 49%

Section: Introductionmentioning

confidence: 77%

Section: Analysis Techniquementioning

confidence: 99%

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Statistical characteristics of PMWE observations by the EISCAT VHF radar

Strelnikova¹,

Rapp

2013

Ann. Geophys.

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“…Characteristic mesosphere echoes are observed: polar mesosphere summer echoes (PMSEs) and polar mesosphere winter echoes (PMWEs) (e.g., Ecklund and Balsley 1981;Hoppe et al 1988;Rapp and Lübken 2004;Zeller et al 2006;Morris et al 2011). According to turbulence theories, expected turbulence in the polar mesosphere seems too weak to explain the observed strength of both echoes (e.g., Rapp et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Mesosphere Echoes over Antarctica Obtained Using PANSY and MF Radars

Tsutsumi

Sato

et al. 2017

SOLA

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We investigated characteristics of mesosphere echoes over Syowa Station (69S) in the Antarctic, which were detected by the Program of the Antarctic Syowa Mesosphere, Stratosphere and Troposphere/Incoherent Scatter (PANSY) radar (47 MHz) and Medium Frequency (MF) radar (2.4 MHz). Winter echoes from the PANSY radar and low altitude MF echoes below approximately 70−75 km mostly coexisted, appearing during the daytime as well as for a few hours post sunset. Summer echoes in the lower height region were absent in both radar observations, suggesting a close relationship in the generation mechanisms of these two radar echoes. High correlation between local K-index and the occurrence of winter echoes suggested that electron density enhancement due to ionized particle precipitation was one of the triggers of echo generation. Angles of arrival of the MF echoes were more isotropic in winter. Because gravity wave activity is much higher in winter over Syowa, higher turbulence energy caused by gravity wave breaking may also be responsible for the generation of the winter echoes and their isotropic behavior. The horizontal wind velocities of the two systems were further compared and agreed well throughout the height region of 60−90 km.

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“…Kirkwood et al, 2002), and Andenes, Norway (e.g. Zeller et al, 2006), as well as from Davis in Antarctica, at 69 • S (Morris et al, 2011). They are most of the time rather weak and visible regularly only to very high power VHF radars such as the former Poker Flat 50 MHz radar or the new MAARSY radar in Andenes (e.g.…”

Section: Introductionmentioning

confidence: 99%

High-speed solar wind streams and polar mesosphere winter echoes at Troll, Antarctica

et al. 2015

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Abstract.A small, 54 MHz wind-profiler radar, MARA, was operated at Troll, Antarctica (72 • S, 2.5 • E), continuously from November 2011 to January 2014, covering two complete Antarctic winters. Despite very low power, MARA observed echoes from heights of 55-80 km (polar mesosphere winter echoes, PMWE) on 60 % of all winter days (from March to October). This contrasts with previous reports from radars at high northern latitudes, where PWME have been reported only by very high power radars or during rare periods of unusually high electron density at PMWE heights, such as during solar proton events. Analysis shows that PWME at Troll were not related to solar proton events but were often closely related to the arrival of high-speed solar wind streams (HSS) at the Earth, with PWME appearing at heights as low as 56 km and persisting for up to 15 days following HSS arrival. This demonstrates that HSS effects penetrate directly to below 60 km height in the polar atmosphere. Using local observations of cosmic-noise absorption (CNA), a theoretical ionization/ion-chemistry model and a statistical model of precipitating energetic electrons associated with HSS, the electron density conditions during the HSS events are estimated. We find that PMWE detectability cannot be explained by these variations in electron density and molecularion chemistry alone. PWME become detectable at different thresholds depending on solar illumination and height. In darkness, PWME are detected only when the modelled electron density is above a threshold of about 1000 cm −3 , and only above 75 km height, where negative ions are few. In daylight, the electron density threshold falls by at least 2 orders of magnitude and PWME are found primarily below 75 km height, even in conditions when a large proportion of negative ions is expected. There is also a strong dawn-dusk asymmetry with PWME detected very rarely during morning twilight but often during evening twilight. This behaviour cannot be explained if PMWE are caused by small-scale structure in the neutral/molecular-ion gas alone but may be explained by the presence of charged meteoric dust.

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First observations of Southern Hemisphere polar mesosphere winter echoes including conjugate occurrences at ∼69°S latitude

Cited by 18 publications

References 20 publications

Statistical characteristics of PMWE observations by the EISCAT VHF radar

Statistical characteristics of PMWE observations by the EISCAT VHF radar

Characteristics of Mesosphere Echoes over Antarctica Obtained Using PANSY and MF Radars

High-speed solar wind streams and polar mesosphere winter echoes at Troll, Antarctica

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