1. SuperDARN operations
Pasha Ponomarenko

2. Outline Operational principles Antenna design and coverage
Pulse sequence and ACF
Data processing and presentation

3. Just to remind: The Main Objective
Mapping 2D ionospheric plasma circulation at high latitudes

4. Operation principles
Resolving 2D ionospheric plasma velocities in range-azimuth (horizontal) domain
Azimuth: multi-beam pattern
Range: pulsed mode (time delay)
Line-of-sight Velocity: Doppler shift
Velocity vector:
receiving echoes from the same areas by different radars (i.e. from different directions)
fitting to a velocity model

5. Phased array: Azimuthal scan
SuperDARN:
main array: 16 log-periodic antennae
interferometer: 4 log-periodic antennae
resolution: ~3.5 deg
coverage (16 beams): ~54 deg
phase shift

6. Field of view (FoV)
Each radar consecutively scans through 16 directions (“beams”) every 1or 2 minutes.
Along each beam the returned echoes are sampled at 45-km steps forming “range gates” (max. range~3500 km)
Total FoV consists of ~1200 range-beam cells

7. Pulse sequence & complex ACF
Radar emits a sequence of 7 or 8 pulses
For each range gate a complex autocorrelation function (ACF) is calculated

8. SuperDARN software: FITACF
Experimental ACF
ptab[mppul] short mppul Pulse table.
ltab[2][mplgs] short 2,mplgs Lag table.
pwr0[nrng] float nrng Lag zero power.
slist[0-nrng] short 0-nrng List of stored ranges.
nlag[0-nrng] short 0-nrng Number of points in the fit.
qflg[0-nrng] char 0-nrng Quality of fit flag for ACF.
gflg[0-nrng] char 0-nrng Ground scatter flag for ACF.
p_l[0-nrng] float 0-nrng Power from lambda fit of ACF.
p_l_e[0-nrng] float 0-nrng Power error from lambda fit of ACF.
p_s[0-nrng] float 0-nrng Power from sigma fit of ACF..
p_s_e[0-nrng] float 0-nrng Powr error from sigma fit of ACF.
v[0-nrng] float 0-nrng Velocity from ACF.
v_e[0-nrng] float 0-nrng Velocity error from ACF.
w_l[0-nrng] float 0-nrng Spectral width from lambda fit of ACF.
w_l_e[0-nrng] float 0-nrng Spectral width error from lambda fit of ACF.
w_s[0-nrng] float 0-nrng Spectral width from sigma fit of ACF.
w_s_e[0-nrng] float 0-nrng Spectral width error from sigma fit of ACF.
sd_l[0-nrng] float 0-nrng Standard deviation of sigma fit.
sd_s[0-nrng] float 0-nrng Standard deviation of lambda fit.
sd_phi[0-nrng] float 0-nrng Standard deviation of phase fit of ACF.
x_qflg[0-nrng] char 0-nrng Quality of fit flag for XCF.
x_gflg[0-nrng] char 0-nrng Ground scatter flag for XCF.
x_p_l[0-nrng] float 0-nrng Power from lambda fit of XCF.
x_p_l_e[0-nrng] float 0-nrng Power error from lambda fit of XCF.
x_p_s[0-nrng] float 0-nrng Power from sigma fit of XCF.
x_p_s_e[0-nrng] float 0-nrng Power error from sigma fit of XCF.
x_v[0-nrng] float 0-nrng Velocity from XCF.
x_v_e[0-nrng] float 0-nrng Velocity error from XCF.
x_w_l[0-nrng] float 0-nrng Spectral width from lambda fit of XCF.
x_w_l_e[0-nrng] float 0-nrng Spectral width error from lambda fit of XCF.
x_w_s[0-nrng] float 0-nrng Spectral width from sigma fit of XCF.
x_w_s_e[0-nrng] float 0-nrng Spectral width error from sigma fit of XCF.
phi0[0-nrng] float 0-nrng Phase determination at lag zero of the ACF.
phi0_e[0-nrng] float 0-nrng Phase determination error at lag zero of the ACF.
elv[0-nrng] float 0-nrng Angle of arrival estimate.
elv_low[0-nrng] float 0-nrng Lowest estimate of angle of arrival.
elv_high[0-nrng] float 0-nrng Highest estimat of angle of arrival.
x_sd_l[0-nrng] float 0-nrng Standard deviation of lambda fit of XCF.
x_sd_s[0-nrng] float 0-nrng Standard deviation of sigma fit of XCF.
x_sd_phi[0-nrng] float 0-nrng Standard deviation of phase fit of XCF.
FITACF

9. Main estimated parameters
ACF power
Signal-to-noise ratio (“power”) [dB] – maximum ACF power
Spectral width [m/s] – ACF power decay time
Line-of-sight velocity (“velocity”) [m/s] – ACF phase slope
ACF phase

10. Velocity vector measurements
Overlapping FoVs provide line-of-sight measuremets from two different directions at the same location
They are combined into a 2D velocity vector

11. Plasma circulation (“convection”) maps
Velocity vectors from different radars are combined into a plasma circulation map
Electric field distribution is calculated from velocities based on ExB assumption

12. Plotting data: range-time maps

13. Plotting data: fan plots

14. Attention: Software availability!
SuperDARN “starter’s kit” that contains ready-to-use IDL routines which have been tested on Chapman:
reading fitted data from the standard radar output files into IDL variables
range-time plotting
plotting “fan” diagrams (maps, coordinate systems etc)
PDF files describing SuperDARN data formats/variables/parameters