Space Weather Studies with EISCAT_3D:Developing the Science Case

Ian McCrea on behalf of the EISCAT_3D Project Team

Five key capabilities:

Volumetric imaging (enabled by digital beam forming)

Aperture Synthesis imaging => sub-beamwidth structures

Multistatic configuration => 3D vector velocities

Greatly improved sensitivity (e.g. 32 000 antenna elements in transmitter, 16 000 in receivers)

Transmitter flexibility (e.g. coding, beam-forming)

These abilities have never before been combined in a single radar!

EISCAT_3D Key Capabilities

EISCAT_3D Design Principles• Distributed phased array with multiple sites• At least one active site• Multiple receive sites, with optimised geometry • Support for co-located instruments

• Highly flexible transmitter• High VHF frequencies (e.g. 233 MHz)• Narrow bandwidth on transmit• Wider bandwidth on receive

• Possibly different arrays for Tx and Rx• Rx array distributed for imaging• Low-elevation capability

• Capable of continuous operations• Unattended operations at remote sites• Possibility to adapt experiments in real-time• Significant data processing at central site

Location of EISCAT_3D

EISCAT_3D will be located within the auroral oval and on the equatorward edge of the polar vortex: key regions for global atmosphere-ionosphere system!

Statistical auroral oval (depends on UT and Kp index).

Schematic figure of winter polar vortex (courtesy of M. Clilverd).

69.4 N 30.0 E

69.58 N 19.22 E

68.2 N 14.3 E

One possible site orientation

Final site selection still undecided

Site surveysin progress

EISCAT_3D TransmittersCentre frequency 220-250 MHz

Peak output power > 2 MW

-1 dB power bandwidth > 5 MHz

Pulse length 0.5 to 2000 us

Pulse repetition frequency 0 to 3000 Hz

Arbitrary waveform generation

Must be rugged and mass-producible at low cost

EISCAT_3D Antennas•The “Renkwitz Yagi”•Centre frequency 235 MHz•Bandwidth 12 MHz (>20 dB)•Opening angle 40o (core array), 30o (receiver arrays)•Arbitrary polarisation•Good sidelobe supression

•7dB gain over 10% relative bandwidth•Need to be mechanically robust (e.g. due to snow loading)•Bandwidth should not be affected by icing•Mutual coupling needs to be acceptable

LOFAR HBA Test Array at Kilpisjärvi• HBA Array – summer 2011

• LBA Array – summer 2012

EISCAT_3D Signal Processing

Design study did not specify a chosen system due to speed of evolution in DSP technology

Preparatory phase will evaluate the use of multi-channel samplers and high performance computing for DSP and beam-forming

EISCAT_3D technology can be prototyped on a range of different systems, e.g. the MST radar at Sodankyla.

EISCAT_3D Work Packages• WP1: Management and reporting• WP2: Legal and logistical issues• WP3: Science planning and user engagement• WP4: Outreach activities• WP5: Consortium building• WP6: Performance specification• WP7: Signal processing• WP8: Antenna, front end and timing• WP9: Transmitter development• WP10: Aperture synthesis imaging• WP11: Software theory & implementation• WP12: System control• WP13: Data handling & distribution• WP14: Mass-production & reliability

Science Working Group (SWG)

• Typically 2+5 members• Membership rotated on a yearly basis• Works to keep the Science Case up-to-date and bring

new ideas from the existing and new EISCAT user groups.

• Helps to compile a list of contact persons/groups for potential new EISCAT_3D user communities

WP3: Science Planning and User Engagement

Science Working Group after a day’s work with the EISCAT_3D Science Case

The Science Case Document:A. Atmospheric physics and global change

B. Space and plasma physics

C. Solar system research

D. Space weather and service applications

E. Radar techniques, coding and analysis

Appendix A: Table of EISCAT_3D radar performance requirements by science topics

EISCAT_3D Science Case, 1st version 30.6.2011

High-Latitude Electron Density:Large-Scale Structure

• Targets:– TEC structure and variability (for GPS)– Density peak and profile variations (for

communications)

• Wide view field for position of oval, trough etc.

• Quasi-simultaneous imaging gives real-time maps

• Continuous operation for effects of geomagnetic disturbance on density

• Independent TEC information from multi-path Faraday rotation

Image Credit: Lucilla Alfonsi, INGV

High-Latitude Electron Density:Small-Scale Structure

Targets:– Small scale irregularities (scintillation)– Flow/gradient regions (irregularity generation)

• Large-scale imaging allows potential scintillation regions to be identified

• Aperture synthesis imaging allows investigation of small structures

• Continuous operation allows monitoring capability and climatology determination

• Obvious synergy with satellite measurements and models

Phase scintillation signatures on disturbed and active days

Image Credit: Lucilla Alfonsi, INGV

Targets:o Real-time E-fields o Conductivity, current and heating rate mapso Relationship to irregularity and structure

• Continuous monitoring provides possibility to separate solar wind, auroral, diurnal effects

• Long-period data provide climaotology of electrodynamic effects

• Interaction between monitoring and modelling can improve understanding of hazards e.g. GICs in northern Europe.

Electrodynamics

Image Credit: Lucilla Alfonsi, INGV

Observation

Simulation

Targets:o Comparison/validation for modelso Data input/assimilation techniqueso Semi-empirical models from data

• Broad coverage and long-period data provide a huge resources for modelling community

• Lots of interesting science from data/model comparisons in IPY

• Need more engagement with the modelling community on critical parameters to measure; timing and frequency of observations

Modellling

Image Credit: Frederic Pitout, Toulouse

Targets:o Short-term thermospheric change during disturbanceso Identification of long-term trends (thermosphere

contraction)

• Long-term data allows monitoring role

• Continuous operations ensure effects of short-term disturbances are measured.

• Complement to international modelling community

• Combination of ion velocity and airglow measurements gives neutral density measurements via momentum equation.

• Satellite tracking and ranging capabilities provide additional thermosphere moniitoring capabilities.

Thermosphere

Space Debris• Space debris is integral part of EISCAT data

(otherwise thrown away)

• ESA buys EISCAT time for space debris studies

• Regular monitoring allows identification of “space debris” events (e.g. Cosmos/Iridium)

• Potential for individual object tracking/ranging using adaptive beams

• Observation compares and drives modelling (e.g. debris cloud evolution)

• Obvious synergy with thermosphere measurements

Image Credit: Juha Vierinen, SGO

• Solar wind monitoring via scintillation of radio stars

• Multi-site observations yield solar wind velocity

• Single site observations give irregularity content and variability

• Solar wind acceleration processes

• Identification of fast/slow streams

• Irregularity content of solar wind

• Solar wind tomography and CMEs

• Solar wind magnetic structure (?)

Solar Wind Studies

Image Credits: Steve Crothers (STFC-RAL) and Mario Bisi (Aberystwyth)

EISCAT_3D has clear potential as a space weather instrument

Capabilities go beyond anything available to the radar community

Realising this potential needs:

• Well thought-out plan of operations

• Good connection to other instrument programs

• Better connection to/support for models

To do this, we need to involve space weather community at a higher level within EISCAT

Conclusions

Get involved!

In the new EISCAT Scientific Association, new members (at different commitment levels) are welcomed!

Welcome also to the 4th EISCAT_3D User meeting in Uppsala 23–25 May 2012! 1st day will be dedicated to Space Weather issues.

Science case document:http://www.eiscat3d.se

Contact:• anita.aikio@oulu.fi• ian.mccrea@stfc.ac.uk• esa.turunen@eiscat.se