Polar mesospheric summer echoes (PMSE) is the phenomenon of anomalous radar echoes found between 80 and 90 km in altitude from May through early August in the Arctic, and from November through to February in the Antarctic. These strong radar echoes are associated with the extremely cold temperatures that occur above continental Antarctica during the summer. Rocket and radar measurements indicate that a partial reflection from a multitude of ion layers and constructive interference causes at least some of the PMSE.
Generally PMSE exhibits dramatic variations in height and intensity as well as large variations in Doppler shift. PMSE exhibit strong signal power enhancements of scattering cross section at VHF radar frequencies in the range 50 MHz to 250 MHz, at times even to over 1 GHz, that occur in summer at high latitudes. The peak PMSE height is slightly below the summer mesopause temperature minimum at 88 km, and above the noctilucent cloud (NLC) and/or polar mesospheric cloud (PMC) layer at 83–84 km. The usual instrument for observing PMSE is a VHFMesosphere-Stratosphere-Troposphere (MST) radar, although LIDARs and sounding rockets have also been used.
PMSE is believed to be caused by structural irregularities in the ionosphericelectron density at lower altitudes. The exact cause of PMSE is not yet known, although theorists have proposed steep electron density gradients, heavy positive ions, dressed aerosols, gravity waves and turbulence as possible explanations. [1]
PMSE occurs in both the Arctic and Antarctic regions, and is sometimes accompanied by noctilucent clouds. A much less frequent phenomena, related to PMSE, is known as Mesospheric Summer Echoes (MSE). MSE can be observed at middle latitudes, e.g., along the Baltic coast. Many years of MSE observations using VHFradars in Northern Germany show that MSE occurs less frequently because the formation mechanism requires the transport of very cold polar air by equatorward mesospheric winds. [2]
polar, mesospheric, summer, echoes, this, article, includes, list, references, related, reading, external, links, sources, remain, unclear, because, lacks, inline, citations, please, help, improve, this, article, introducing, more, precise, citations, january,. This article includes a list of references related reading or external links but its sources remain unclear because it lacks inline citations Please help improve this article by introducing more precise citations January 2017 Learn how and when to remove this message Polar mesospheric summer echoes PMSE is the phenomenon of anomalous radar echoes found between 80 and 90 km in altitude from May through early August in the Arctic and from November through to February in the Antarctic These strong radar echoes are associated with the extremely cold temperatures that occur above continental Antarctica during the summer Rocket and radar measurements indicate that a partial reflection from a multitude of ion layers and constructive interference causes at least some of the PMSE Generally PMSE exhibits dramatic variations in height and intensity as well as large variations in Doppler shift PMSE exhibit strong signal power enhancements of scattering cross section at VHF radar frequencies in the range 50 MHz to 250 MHz at times even to over 1 GHz that occur in summer at high latitudes The peak PMSE height is slightly below the summer mesopause temperature minimum at 88 km and above the noctilucent cloud NLC and or polar mesospheric cloud PMC layer at 83 84 km The usual instrument for observing PMSE is a VHF Mesosphere Stratosphere Troposphere MST radar although LIDARs and sounding rockets have also been used PMSE is believed to be caused by structural irregularities in the ionospheric electron density at lower altitudes The exact cause of PMSE is not yet known although theorists have proposed steep electron density gradients heavy positive ions dressed aerosols gravity waves and turbulence as possible explanations 1 PMSE occurs in both the Arctic and Antarctic regions and is sometimes accompanied by noctilucent clouds A much less frequent phenomena related to PMSE is known as Mesospheric Summer Echoes MSE MSE can be observed at middle latitudes e g along the Baltic coast Many years of MSE observations using VHF radars in Northern Germany show that MSE occurs less frequently because the formation mechanism requires the transport of very cold polar air by equatorward mesospheric winds 2 See also editIonogramReferences edit Zeller O Hoffmann P Bremer J Singer W 2009 04 21 Mesosphere summer echoes temperature and meridional wind variations at mid and polar latitudes Journal of Atmospheric and Solar Terrestrial Physics 71 8 9 931 942 Bibcode 2009JASTP 71 931Z doi 10 1016 j jastp 2009 03 013 Pokhotelov D Stober G Chau J L 2019 04 17 Statistical climatology of mid latitude mesospheric summer echoes characterised by OSWIN Ostsee Wind radar observations Atmospheric Chemistry and Physics 19 7 5251 5258 Bibcode 2019ACP 19 5251P doi 10 5194 acp 19 5251 2019 External links editPolar mesosphere summer echoes PMSE review of observations and current understanding PMSE at EISCAT 224 MHz observations First observations of Polar Mesosphere Summer Echoes PMSE above Davis Antarctic PMSE nbsp This science article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Polar mesospheric summer echoes amp oldid 1200602184, wikipedia, wiki, book, books, library,
