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SuperDARN Polar Cap Potential
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.. contents:: Table of contents

The Super Dual Auroral Radar Network (SuperDARN) is an international network of
High Frequency coherent scatter radars. A map of the fields of view of the radars
currently in operation can be seen in Figure 1: INAF-IAPS manages the radar pair of
Dome C East (DCE) and Dome C North (DCN) located at the Concordia station, in
Antarctica, whose fields of view are shaded in green in the figure.
The SuperDARN concept is described in detail in [2]. A SuperDARN radar is a bistatic
apparatus (i.e. the same antennae and the same electronics are used to both transmit
and receive signals to/from the ionosphere), which works in the 8-20 MHz frequency
range: coded sequences of radio pulses are steered through a field of view several tens
degrees wide along a number of “beams” (directions), so that the whole field of view
is covered in one or two minutes, depending on the operating mode. Along each beam,
the pulse sequence defines from 75 to 100 range gates, from 180 km up to 3000 km
from the radar site, where the radio signals encounter plasma density irregularities in
the ionosphere, which cause such signals to be scattered back along the same direction.
As ionospheric irregularities are dragged in the large scale convection at high latitudes, the measure of the Doppler phase shift between the emitted and backscattered waves
allows to infer the velocity of the ambient plasma with respect to the sounded direction
and gate.

References
~~~~~~~~~~

https://www.sciencedirect.com/science/article/abs/pii/S136468260600263X

[1] SuperDARN Data Analysis Working Group, Thomas, E. G., Reimer, A. S., Bland,
E. C., Burrell, A. G., Grocott, A., Ponomarenko, P. V., Schmidt, M. T., Shepherd, S. G.,
Sterne, K. T., and Walach, M.-T, SuperDARN Radar Software Toolkit (RST) 5.0 (v5.0).
Zenodo (2022). https://doi.org/10.5281/zenodo.7467337

[2] Greenwald, R.A., Baker, K.B., Dudeney, J.R. et al., DARN/SuperDARN, A global
view of the dynamics of high-latitude convection, Space Sci Rev, 71, 761–796 (1995).
https://doi.org/10.1007/BF00751350

[3] Ruohoniemi, J.M., and K.B. Baker, Large-scale imaging of high-latitude
convection with Super Dual Auroral Radar Network HF radar observations, J. Geophys. Res., Space Physics, 103, 20797-20811 (1998).https://doi.org/10.1029/98JA01288

[4] Thomas, E. G., and S. G. Shepherd, Statistical Patterns of Ionospheric Convection
Derived From Mid-latitude, High-Latitude, and Polar SuperDARN HF Radar
Observations, J. Geophys. Res., Space Physics, 123(4), 3196-3216 (2018).
https://doi.org/10.1002/2018JA025280

[5] Baker, K. B., and S. Wing, A new coordinate system for conjugate studies at high latitudes, J. Geophys. Res., 94(A7), 9139 (1989).https://doi.org/10.1029/JA094iA07p09139
[6] Shepherd, S. G., Altitude-Adjusted Corrected Geomagnetic Coordinates: Definition
and Functional Approximations, J. Geophys. Res., Space Physics, 119(9), 7501-7521
(2014). https://doi.org/10.1002/2014JA020264

Dataset summary
~~~~~~~~~~~~~~~

.. list-table::

  * - **internal_name:**
    - inaf_cpcp_superdarn_datacube
  * - **publisher:**
    - INAF
  * - **alph_code:**
    - 31
  * - **id_tmp:**
    - 71
  * - **short_name:**
    - SuperDARN CPCP
  * - **identifier:**
    - aspis://inaf/cpcp_superdarn_datacube
  * - **dynamic:**
    - static
  * - **size:**
    - 200MB
  * - **format:**
    - csv
  * - **type:**
    - timeseries
  * - **records_number:**
    - 1515672
  * - **time_start:**
    - 2015-06-21
  * - **time_stop:**
    - 2017-09-11
  * - **spatial:**
    - IONO
  * - **messenger:**
    - electrons,
  * - **spectral_min:**
    - 0
  * - **spectral_max:**
    - 1
  * - **spectral_units:**
    - dimensionless
  * - **observable:**
    - IMF,GEOINDEX
  * - **latest update:**
    - 2024-04-04 01:53:25

Columns specification
~~~~~~~~~~~~~~~~~~~~~

.. list-table:: 
   :widths: 7 20 15 10 48
   :align: right 
   :header-rows: 1

   * - progr
     - column
     - units
     - type
     - description
   * - 1
     - time
     - UTC
     - datetime
     - Time representation ISO8601: YYYY-MO-DYTHR:MN:SC
   * - 2
     - hem
     - 
     - string
     - Flag identifying the hemisphere where data are taken for a given record. “N”=North; “S”=South
   * - 3
     - ndata
     - counts
     - int
     - Number of velocity vectors actually measured by the radars in the given time interval
   * - 4
     - minlat
     - deg
     - int
     - Low latitude limit for the convection: it is the 0 described in Section 2.
   * - 5
     - latpole
     - deg
     - float
     - Geographic latitude of the AACGM pole (North or South). It can be useful  for  coordinate transformations.
   * - 6
     - lonpole
     - deg
     - float
     - Geographic longitude of the AACGM pole (North or South). It can be useful for coordinate transformations.
   * - 7
     - radpole
     - Earth radii (Re=6371.2 km)
     - float
     - Distance from the centre of the Earth of the AACGM pole.
   * - 8
     - imfbx
     - nT
     - float
     - GSM* x component of the interplanetary magnetic field. Data are taken from DSCOVR spacecraft, ballistically propagated to the centre of the Earth, median filtered and averaged in the 2 minutes time intervals of the radar scans. IMF is used to select the model patterns to be added to the measured vectors in order to reconstruct convection in the whole polar cap.
   * - 9
     - imfby
     - nT
     - float
     - GSM* y component of the interplanetary magnetic field.
   * - 10
     - imfbz
     - nT
     - float
     - GSM* z component of the interplanetary magnetic field.
   * - 11
     - imfbt
     - nT
     - float
     - IMF strength. Btot = sqrt(Bx^2 + By^2 + Bz^2)
   * - 12
     - kpr
     - 
     - string
     - Range of geomagnetic Kp index during the given time interval. This parameter is used to select the model patterns to be added to the measured vectors in order to reconstruct convection in the whole polar cap. This field represents an information useful to be reported in the convection maps.
   * - 13
     - cpcp
     - V
     - float
     - Cross  Polar  Cap  Potential: Maximum  potential difference through the polar cap.
   * - 14
     - maxpot
     - V
     - float
     - Maximum positive value of the electric potential.
   * - 15
     - minpot
     - V
     - float
     - Minimum negative value of the electric potential.
   * - 16
     - l
     - counts
     - int
     - l-order of the harmonic expansion of the potential.
   * - 17
     - m
     - counts
     - int
     - m-order of the harmonic expansion of the potential. -l ≤ m ≤ l
   * - 18
     - coef
     - V
     - float
     - Alm coefficient of the harmonic expansion of the potential. If m<0, then the coefficient is the Blm in Eq. 2.
