Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California
Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California
Small scale studies with AMISR
Anja StrømmeEISCAT Svalbard Radar
Currently atSRI International Menlo
Park
Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California
How small are “small scales?”
•In this talk, the term small scales refers to both spatial and temporal structuresSpatial: Significantly smaller than the radar beam
horizontal width of ~10-100 metersTemporal: 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
Motivation for Small Scale Studies (1)Guisdap does not fit ...or even worse: it does!
Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California
Temporal......
Ion line spectra from the EISCAT Svalbard Radar for 4 consecutive 10s data dumps
Motivation for Small Scale Studies (2)
Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California
Grydeland et al. 2003 (GRL)
Grydeland et al 2004 (Ann. Geophys.)
Motivation for Small Scale Studies (3)
Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California
Ion and plasma line enhancements
Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California
How can we use AMISR for these studies?
•Frequency and Location
Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California
Invariant Latitude
o10.75ESR
o2.74Sondrestrom
o1.66
o4.53
EISCAT UHF and VHF
Millstone Hill
224 1290933500440
EISCAT VHF
Millstone Hill
EISCAT UHF
ESR
Sondrestrom
€
83.37o AMISR AMISR
AMISR
€
66.7o
Frequency and location
Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California
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
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
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
“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
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
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
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
Interferometry
BAn IS radar can not directly resolve structures smaller than the radar beam, given by beam width and pulse length
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.
If coherent structures exist within the radar beam, interferometric methods can be used to resolve them
Anja Strømme AMISR Science planning Workshop, 12. Oct 2006, Asilomar, California
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 45x45 (=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
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
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”)