Small scale studies with AMISR

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”)