New PMSE Observations with the EISCAT 500-MHz Svalbard Radar and the SOUSY 53.5-MHz Svalbard Radar

Röttger, J.1, Rapp, M.2, Qiang, L.2, Trautner, J.2, Serafimovich, A.3 and Hall, C.4

1 Max-Planck-Institut, Northeim, Germany
2 Leibniz-Institut für Atmosphärenphysik, Germany
3 Leibniz-Institut für Atmosphärenphysik, Germany, now at Bayereuth University, Germany
4 University of Tromsø, Norway

A campaign was carried out between 6 and 30 June 2006 to compare observations of Polar Mesosphere Summer Echoes with the SOUSY Svalbard Radar (SSR)and the EISCAT Svalbard Radar (ESR), which are almost collocated near Longyearbyen on Svalbard (78 deg N). The EISCAT Svalbard Radar was operated in a special complementary code mode which for the first time allowed this radar to be used with the high range resolution of 300 meters for D-region/mesosphere studies. This resolution is equal to the range resolution of the SOUSY Svalbard Radar. For the first time we are now able to compare spectra of PMSE obtained on the two different Bragg scales of 2.8 m (SSR) and 0.3 m (ESR) with the same range resolution, although both radars have different antenna beam widths.

First we present some statistics of PMSE observed with the EISCAT Svalbard Radar during the month of June 2006, and compare it with observations of the SSR.

Then we present spectrum analyses with both radars. We can demonstrate that the spectra of SSR are much wider and show less structure than the ESR spectra. This is likely due to the wider beam width of the SSR (5 deg) as compared to that of the ESR (1.6 deg). We will also describe one particular structure which is characterized by a layer of less than 300 m thickness which show clear features of Kelvin-Helmholtz-Instability. This feature is more clearly recognized in the narrower beam width observations of the ESR. We will also discuss potential implications which these observations have on the interpretation of PMSE observed with wide beam radars.

We kindly acknowledge the assistance of Assar Westman and Ingemar Häggström of EISCAT and his colleagues for preparing the EISCAT Svalbard Radar code and doing the operational oversight.