The turbopause is the demarcation between atmospheric mixing by turbulence (below) and molecular diffusion (above). When studying concentrations of trace species in the atmosphere, and particularly long-term change, it may be important to understand processes present, together with their temporal evolution that may be responsible for redistribution of atmospheric constituents. The general ...

Operation of a Meteor Wind Radar (MWR) at Eureka, Ellesmere Island (80° N, 86° W) began in February 2006; this is the location of the Polar Environmental and Atmospheric Research Laboratory (PEARL), operated by the "Canadian Network for the Detection of Atmospheric Change" (CANDAC). The first 36 months of wind data (82–97 km) are here combined with contemporaneous winds from the Meteor Wind Radar ...

Nordlyset har vært omgitt av både mystikk og beundring. Det har inspirert kunstnere til betagende kunstverk og skremt andre til fortvilelse. Det er umulig å fastslå når den første beskrivelsen av nordlys har funnet sted. I det følgende kapitlet skal vi gå historiens vei og presentere noen inntrykk av de tidligste forestillingene om fenomenet, slike som en kan finne spør av i den muntlige tradisjon, ...

This paper studies thermally excited emissions in the polar ionosphere derived from European Incoherent Scatter Svalbard radar measurements from the years 2000–2015. The peak occurrence is found around magnetic noon, where the radar observations show cusp-like characteristics. The ionospheric, interplanetary magnetic field and solar wind conditions favor dayside magnetic reconnection as the dominant ...

We have noted sporadic instances of strong isolated reflections of medium frequency (MF) radar waves from the mesosphere from as low as 50 km altitude and have devised a set of criteria for isolating these apparently anomalous echoes from those normally occurring from progressive partial reflections in the D-region. The object of this study is to map the occurrences of such echoes facilitating ...

A new fve-wavelength photometer was developed and installed at the EISCAT Tromsø site (69.6°N, 19.2°E) in January 2017. The photometer consists of two units: an optical unit and a control unit together with a PC. The photometer is capable of simultaneously observing auroral emissions with fve wavelengths. A uniqueness of the present system is its capability of precise pointing, which enables ...

Nordlys dannes av gass og strømmer ut fra sola. Denne solvinden stoppes av jordas magnetfelt, og energien i vinden fra sola overføres til negative og positive ladede partikler (elektroner og protoner) som skytes ned fra jordatmosfæren og gir nordlys. Vi skal i det følgende fortelle litt om sola, og hvorfor det er en gasstrøm fra sola. Vi skal også diskutere hva som skjer når solvinden treffer sola