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Project description
Scientific questions:
- Investigat the formation mechanism(s) of HF radar backskatter irregularities in the winter cusp ionosphere.
- Examine which role tail reconnection plays in the different phases of a geomagnetic substorm by observing
signatures on ground.
- Develope new instrumentation for sounding rockets using micro electro mechanical systems to fit the experiments
into the Hotel Payload beeing developed at Andøya Rocket Range. (ICI-II)
Introduction
One problem complex is related to the formation mechanism(s) of HF radar
backscatter irregularities in the winter cusp ionosphere. This problem
is of practical interest to HF radio communication within the polar cap
and in the Barents Sea area, but may also give rise to attenuation of GPS
signals under severe solar storms.
The other problem complex is related to the dynamics of substorm auroras and
tail reconnection. First we want to establish a ground-based method to
continuously observe spatio-temporal variations of tail reconnection. Such
a tool will pave the road for a detailed examination of the transient nature of
reconnection, and aid a quantitative assessment on whether reconnection play a
significant role in other phases than the expansion phase of a substorm. We have
recently found substantial indications that reconnection does also occur in the
so-called growth phase. In order to verify the ground-based technique of
reconnection rate measurements, we plan to fly through the poleward boundary of
substorm auroras. This will give us an unparalleled opportunity to investigate
the electrodynamics of the ionosphere-magnetosphere coupling related to auroral
transients observed at the poleward boundary of substorm aurora.
This project aimes to combine data collected from detaild in-situ measurements
from sounding rockets and the well-developed network of radar and optical instruments
in North-Norway and Svalbard.
Irregularities
The coherent HF radar obtain backscatter from field-aligned plasma iregularities of decameter scale. Several
candidates of generation mechanisms has been suggested; the gradient drift instabillity, shear instabillity,
"stirring" or flux tube interchange and current convective instabillity. High-resolution measurements by
sounding rockets is the only approch to discriminate between the suggested production modes.
Tail reconnection
It is possible to monitor the ionospheric respons to dayside reconnection by finding the boundary between open
and closed field lines. In this study we want to establish a method to also monitor tail reconnection. There
are some ground basede techniques avaliable but they are not very accurate and need validation by high resolution
in-situ measurements. This will be possible from Svalbard, combining sounding rocket experiment with groundbased
instrumentation.
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