EISCAT Facility update 2013

EISCAT Facility update 2013

M. Kosch, Lancaster University, UK

M. T. RietveldEISCAT, Ramfjordbotn, Norway.

19th RF Ionospheric Interactions Workshop, 21 - 24 April 2013, Arecibo.

Overview

1) EISCAT organisation and radar status

2) Heating status and recent results

EISCAT Scientific Association EISCAT: Organisation

CAGCouncil Advisory Group

New director: Craig Heinselman (since January 2013)

UHF (933 MHz) radar now monostatic only. GSM mobile phone network interference became too strong at Kiruna & Sodankyla. We are seeking licence extension beyond 2013.

VHF radar now tristatic: Kiruna & Sodankyla converted to 224 MHz. (But Tromsø remains non-field-aligned). Actually, it is tetrastatic, with the KAIRA receiver (LOFAR antenna at Kilpisjarvi, Finland) also receiving signals from the VHF radar.

EISCAT 3D: large funding proposals submitted by Norway and Sweden & hopefully Finland soon. Total cost estimate 132 M€. Core site selection still not decided, but near Ramfjordmoen, possibly further inland.

EISCAT news

receiving antenna, 5.4-8 MHz

transmitting antenna, 5.4 – 8 MHz

4-5.4 MHz

Heating Status, April 2013

Staffing:

One scientist plus one engineer.

Operations:

269 hrs in 2011, 263 hrs in 2012

Users from China, Finland, Japan, Norway, Russia, Sweden, UK, USA.

Publications:

13 in 2011, 6 in 2012, average about 10/yr which is about 20-25% of all EISCAT publications annually.

Heating Technical status:

Transmitters largely OK. One faulty transmitting tube is being rebuilt by Richardson Electronics (USA) to improve the spare part situation.

Array 1 (30dBi gain): Serious rot was found in many of the small wooden poles supporting the feed lines. This array was rebuilt in 1990 and so is showing its age in some areas. Non-treated wood was used in some areas (not the main masts) since a 30+ year lifetime was never envisaged.

Major upgrade work done in recent years on the RF generation, modulation and control hardware and software. Much greater flexibility, computer control of hardware and logging. For example instantaneous frequency/phase/amplitude stepping is possible.

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Publications from the Tromsø HF Facility (& HF hours)

Year

Pub

licat

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HF hours|

Heater starts

operationsTransfer

from Max-Planck to

EISCAT

Maintenance required on some ageing parts in antenna fields- rotting wood.

HF radar experiments with heating transmitters and Array-3 receiver in high demand: mostly low altitude (mesospheric) but also high-altitude (magnetospheric) experiments.

New hardware and software enables computer monitoring and control of certain transmitter hardware functions that were only available via lights and buttons on the console.

Fast frequency and/or phase and/or amplitude modulation is possible now.

Power calibrations and power stepping improved implementation.

Better logging of HF parameters.

Soon a modification to the coaxial switches will allow both reception and transmission on array-3 (5.4-8 MHz, 24 dBi gain).

Heater upgrade: developments and ongoing work

These buttons/lights are now under computer control.

Array-3 feed lines disconnected from transmitters

Using antenna array-3 as a receiver(presently with transmission line disconnected from

transmitter) Power combiners

to transmitter

cable from tx/rx switch to power combiner or digital beam former

to antenna (array-3)

New receiver connection to antenna (without opening the co-axial lines) summer 2013

Recent scientific resultsX-mode excitation of irregularities and HFILBackscatter enhancements on topside (very mysterious)Mesospheric HF echoes received in radar modeMesospheric VHF echo modulationD-region heating model overestimates heating measured by riometer and cross-modulation experiments.Novel API (Artificial Periodic Irregularity) experiments Efficiency of resonant heating calculated.Ion upwelling studies

Modelling the beam pattern with EZNEC suggests that the non-perfect ground may result in the antenna gain and ERP being only about 75% of that calculated assuming a perfect ground. This may help explain some of the discrepancy beyween calculated and measured heating effects in the D region. (e.g. Senior et al., JGR, 116, A04310, doi:10.1029/2010JA016189, 2011).

Laying a ground plane of wires may be a relatively cheap way of increasing the effective radiated power. This is being investigated at present.

8 MHz echoes shown as contours on lower plot

224 MHz echoes in colour with 8 MHz echoes shown as contours

Mesospheric echoes

These apparent densityincreases are a mystery.

But they are not real andare only seen very close

to field-aligned

See the recent paper by Senior et al., 2013 for details, GRL

Examples of ion upwelling in the last few heater pulses

(as well as the mysterious backscatter enhancements)

Mesospheric velocities with API One advantage of the API method is that it allows high resolution vertical velocities to be measured between 50-120 km. Here is an example plot from our 9.12.2011 measurement. Around noon (7000 seconds in to the measurement) there are also some tropospheric echoes. -- from blog by Juha Vierinen: kaira.sgo.fi