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:• [email protected]• [email protected]• [email protected]