Small scale studies with AMISR

1. Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

2. Small scale studies with AMISR Anja Strømme EISCAT Svalbard Radar Currently at SRI International Menlo Park Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

3. How small are “small scales?” • In this talk, the term small scales refers to both spatial and temporal structures • Spatial: Significantly smaller than the radar beam • horizontal width of ~10-100 meters • Temporal: Shorter than traditional pre-integration time - on the order of a few IPP-length • temporal variations of ~0.1 seconds Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

4. Motivation for Small Scale Studies (1) ...or even worse: it does! Guisdap does not fit Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

5. Motivation for Small Scale Studies (2) Temporal...... Ion line spectra from the EISCAT Svalbard Radar for 4 consecutive 10s data dumps Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

6. Motivation for Small Scale Studies (3) Grydeland et al. 2003 (GRL) Grydeland et al 2004 (Ann. Geophys.) Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

7. Ion and plasma line enhancements Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

8. How can we use AMISR for these studies? • Frequency and Location Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

9. AMISR AMISR AMISR Frequency and location Invariant Latitude EISCAT VHF ESR Millstone Hill Sondrestrom ESR EISCAT UHF and VHF EISCAT UHF Sondrestrom Millstone Hill Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

10. How can we use AMISR for these studies? • Frequency and Location • Raw data storage Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

11. Raw data storage By storing the raw voltage off the receivers the integration time can be set to match the process, not the experiment. During EISCAT Svalbard Radar (ESR) experiments enhancement levels of several order of magnitude has been observed, and hence integration time down to fraction of a second is sufficient. In addition we need raw voltage data for cross correlation calculations for interferometry. Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

12. How can we use AMISR for these studies? • Frequency and Location • Raw data storage • “On demand” mode Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

13. “On demand” modes Can have a pulse ”once in a while” looking up B for enhancements during other experiments. Can switch to raw data sampling/better experiment for Naturally Enhanced Ion Acoustic Lines (NEIALs) if some pre- defined threshold is met. Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

14. How can we use AMISR for these studies? • Frequency and Location • Raw data storage • “On demand” mode • Sub-beam width beam steering Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

15. Sub beam width beam steering Important in order to determine the 2-dim extension of the coherent scattering structures Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

16. How can we use AMISR for these studies? • Frequency and Location • Raw data storage • “On demand” mode • Sub-beam width beam steering • Interferometry Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

17. Interferometry An IS radar can not directly resolve structures smaller than the radar beam, given by beam width and pulse length B If coherent structures exist within the radar beam, interferometric methods can be used to resolve them Observations with the ESR 2 antenna interferometer, estimating the horizontal size of the scattering structure to be on the order of a hundred meters. The increased scattering hence originates from as little as 0.3% of the scattering volume, giving a actual enhancement of 4 to 5 order of magnitudes. Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

18. Interferometry • To resolve structures smaller than the radar beam we have to use interferometric methods! A phased array antenna is very well suited to do this IF enough receivers are in place! • Current size of AMISR is about 30x30m, or 45x45 (=0.67m) • To have a resolution of 20m in 100km altitude, one need the longest baseline to be ~750 or ~500m • We need several (small passive) outliers around AMIRS. Lots more about the next generation Incoherent Scatter Radar: EISCAT 3D, including Interferomery possibilities on poster by Gudmund Wannberg later today. Be there! Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

19. How can we use AMISR for there studies? • Frequency and Location • Raw data storage • “On demand” mode • Sub-beam width beam steering • Interferometry • Optics, in particular narrow field of view cameras ON SITE Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California

20. Summary • AMISR will be an important next step into the future of small scale and plasma instability studies of the Earths ionosphere if used correct. • Small offset panels and additional tunable receivers should be added to the Poker Flat AMISR phase to improve/allow interferometric measurements of small coherent structures. • Quick (and automatic?) change of experiment during NEIAL events should be allowed for. • Always sample raw data (not necessarily save it all “forever”) Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California