The SuperDARN Radar network and the RBSP...

RBSP meeting, Sept. 2010

The SuperDARN Radar network and

the RBSP mission

Tim Yeoman



1. The SuperDARN network

2. Radar basics

3. SuperDARN data products

4. Operating modes

5. Radar scheduling and spacecraft coordination

6. SuperDARN and RBSP

The Super Dual Auroral Radar Network

(SuperDARN)

An international cooperation between 11 nations and numerous research groups running ~ 22 high latitude ionospheric radars


Northern hemisphere SuperDARN radars



Southern hemisphere SuperDARN radars



• A network of coherent radars

– sensitive to field aligned irregularities

• Operates in the frequency range 8 - 20 MHz - frequency is selected to:

– Allow refraction to make the radar wave vector to achieve orthogonality,

and

– Allow propagation conditions to get the signal to the area of interest

2. SuperDARN radar basics


Typical operations

involve 1 or 2, 7-

pulse sequences



Pulse sequence is

transmitted

Sampling ends after

time appropriate to last

pulse and maximum

range

For each range of

interest:-

Auto-correlation is

carried out for all delays

available in the pulse

sequence

22 lags are computed to

generate an ACF



Raw and fitted data

Fourier spectrum

Fitted spectrum

Complex ACF

ACF phase variation



A SuperDARN summary

plot

Prime measurements

are:

Backscatter power,

Velocity,

Spectral width



Location of

auroral zone –

particle deposition

Auroral zone

and polar cap

Joule heating

Ground scatter:

Ionospheric

Structure and

absorption, AGWs

and ULF waves

Meteor ablation /

Mesospheric winds

and tides

Sp

ec

tra

l w

idth

V

elo

cit

y B

ac

ks

ca

tte

r p

ow

er



Line-of-sight measurements from

northern hemisphere radars

Northern hemisphere convection

pattern

derived using the “map-potential”

technique

The SuperDARN "map-

potential" technique(Ruohoniemi and Baker, 1998)

Chisham et al., 2007



Grocott et al., 2009

Statistical analysis of

global convection keyed

to substorm phase

3. SuperDARN data

products


Amm et al., 2010Spherical elementary current

analysis for mesoscale structure



Grocott et al., 2006

Field aligned current analysis



Wright et al., 2004

Spectral width: a

diagnostic of overlying

magnetospheric

topology and wave

activity

3. SuperDARN data

products


Chisham et al., 2007

Raw data sample

analysis



4. SuperDARN operating modes

SuperDARN Operational flexibility

• Range resolution (45,30,15 km)

• Number of range gates

• Integration time (≥ 1 s)

• Lag to first range

• Scan mode

• Transmit frequency

• Plus much more in principle (stereo, alternative pulse

sequences, raw data sampling…)


The “stereo”

capability allows two

modes to be run

Simultaneously

Can be interleaved on a

mono radar with a loss of

time resolution



High vs standard

temporal

resolution data


Yeoman

et al., 2010

Yeoman et al., 2010



SuperDARN Operations scheduling

• Common time 50%

Standard radar scans on all SuperDARN radars

• Discretionary time 30%

Special modes on Individual radars

• Special time 20%

Special modes on all SuperDARN radars

• Spacecraft Special/Common time

Common agreed modes on all SuperDARN radars

5. SuperDARN scheduling and spacecraft coordination


Previous major SuperDARN/spacecraft coordinated

operations: scheduling and operation modes

Cluster2001 – 2007. ~10 days per month. 180 km to first gate, 75x45 km gates

All radars in the network sounding the same standard mode: 16 beams, 1 min

scans.

Aim: to ensure maximum network coverage of standard scans

Themis2007 – present. ~10 days per month. 180 km to first gate, 75x45 km gates

Mono radars sound 16 beams (2 min scans) with single interleaved beam (6s).

Stereo radars sound 16 beams Channel A (1 min scans), with single beam on

Channel B (3 s).

Aim: to ensure maximum network coverage of standard scans with added

high time resolution coverage

RBSPShould we be trying out “responsive scheduling” to catch storms?

5. SuperDARN scheduling and spacecraft coordination


The combination of RBSP and SuperDARN offer the opportunity of

studying the coupled inner magnetosphere and ionosphere-thermosphere

as a system.

Science examples:

• Direct comparision of magnetosphere pressure gradients (RBSP) and

field aligned and ionospheric currents (SuperDARN)

• Stormtime global convection and substorm electrodynamics

(SuperDARN) vs. in situ electric fields and particles (RBSP), X-rays

(BARREL)

• Storm effects in the ionosphere

• ULF wave activity and storms

Key SuperDARN data products:

Global electrodynamics, storm conditions, convection, cross polar cap

potential, location of OCFLB, mesoscale convection structures



•ULF wave activity and storms.

SuperDARN can measure ULF wave fields, frequency, ionospheric electric

field, azimuthal structure locally and globally. m up to ~100, (attenuation

factor of ~50 in ground magnetometer data) whilst RBSP measures

energetic particles and chorus waves.

Pc3-5 band (1000 - 10s): Direct measurement on a global scale from all

radars. Ionospheric and ground scatter can provide information (direct

measurement of electric field and Doppler shifts due to wave modulation of

the reflection height). Covered by existing THEMIS mode or similar.

ULF EMIC 10 - 0.2 s: Direct measurement at the lower end of the frequency

scale (all radars), Raw data analysis in the middle (partial array coverage),

spectral width broadening as a diagnostic at the upper end of frequency

scale (all radars).

VLF whistlers 100 Hz- 5 kHz no measurements from SuperDARN



What are the key SuperDARN measurements required by the RBSP

community, for radar operations planning?

• Storm quantification and alerts (together with magnetometers)?

• HF absorption as a low altitude precipitation indicator?

• Global convection response to storms, mesoscale convection?

ULF waves.

• Azimuthal structure?

• Integrated wave power in defined frequency bands?

• Global measurement or latitude/MLT distribution?

• Combined data products with ground magnetometer measurements?



The SuperDARN Radar network and

the RBSP mission

Tim Yeoman


• ULF waves generated by

interactions with energetic

particles within the Earth’s magnetosphere

Baddeley et al. (2004)

Wright & Yeoman (1999)

Powerful radio waves

from SPEAR modify

the upper

atmosphere.

This creates targets

for the CUTLASS

radar

Natural ULF waves

from space then

become visible


Wright et al., 2004

The SuperDARN Radar network and the RBSP...

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