Seminars

Lecturer: Esa Turunen (EISCAT)
Date: 2011-08-18 10:30
Place: Aniara

Enhanced mesospheric NO detected by the EISCAT Svalbard radar during the continuous 1-year IPY experiment

Dr. Esa Turunen
Director, EISCAT Scientific Association
Kiruna, Sweden

The EISCAT Svalbard Radar was operated in a continuous type mode during the
entire first year of the International Polar Year (IPY) interval, starting on 1 March
2007 and ending on 29 February 2008. The ISR experiment used a specially written
IPY mode, which was optimized to ensure also a good coverage in the ionospheric
lower E and D regions, in addition to covering the more standard experiment target,
the ionospheric F peak and reaching into the topside ionosphere. While the ESR IPY
data in the altitude range 100-500 km have been extensively used, for example in
studies including the major initiative in high latitude ionospheric modeling "Towards
more effective physics-based and statistical models of the polar ionosphere", which
was supported by funding from the International Space Science Institute in Berne,
Switzerland; the low altitude IPY data has not yet been utilized. We present analysis
of the ionospheric D-region data, where backscattered power measurements, with 3
km range resolution and 2.25 km steps, start from the altitude of 45 km. Data is
subject to sea and/or tropospheric clutter, which is variable with season/day up to 65
km. However, normally data is usable for altitudes higher than 70 km. The ISR
experiment does not have enough freqency resolution for advanced doppler and
spectral width determinations, but by using a detailed coupled neutral and ion chemistry
model, the Sodankylä Ion Chemistry (SIC) model, one can deduce the
effect of neutral atmospheric variability in the backscattered power data. The
observed electron density enhancement in the autumn, during solar minimum time, is
interpreted as an excess amount of NO being produced elsewhere and transported to
lower mesosphere. The interpretation of the radar observation is supported by
simultaneous satellite measurements of odd nitrogen concentration by the ACE-FTS
instrument.

Created 2011-08-08 23:01:59 by Mats Holmström
Last changed 2011-08-17 10:24:43 by Mats Holmström