English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The influence of the solar proton event (SPE) 14–16 July 2000 on Polar\udMesosphere Summer Echoes (PMSE) is examined. PMSE were observed by the Esrange\udVHF MST Radar (ESRAD) at 67°53'N, 21°06'E. The 30MHz Imaging Riometer for\udIonospheric Studies IRIS in Kilpisjärvi (69°30'N, 20°47'E) registered cosmic radio noise\udabsorption caused by ionisation changes in response to the energetic particle\udprecipitation. An energy deposition/ion-chemical model was used to estimate the\uddensity of free electrons and ions in the upper atmosphere. Particle collision frequencies\udwere calculated from the MSISE-90 model. Electric fields were calculated using\udconductivities from the model and measured magnetic disturbances. The electric field\udreached a maximum of 91mV/m during the most intensive period of the geomagnetic\udstorm accompanying the SPE. The temperature increase due to Joule and particle heating\udwas calculated, taking into account radiative cooling. The temperature increase at PMSE\udheights was found to be very small.\ud\ud</p><p style="line-height: 20px;">\udThe observed PMSE were rather intensive and extended over the 80–90km height\udinterval. PMSE almost disappeared above 86km at the time of greatest Joule heating on\ud15 July 2000. Neither ionisation changes, nor Joule/particle heating can explain the PMSE\udreduction. Transport effects due to the strong electric field are a more likely explanation.  \ud<b>Key words.</b> Meteorology and atmospheric dynamics (middle\udatmospheric dynamics), ionosphere (ionospheric disturbances;\udsolar radiation and cosmic ray effects

Polar mesosphere summer echoes during the July 2000 solar protonevent