Canopus ? A ground-based instrument array for remote sensing the high latitude ionosphere during the ISTP/GGS program

Rostoker, G.; Samson, J. C.; Creutzberg, F.; Hughes, T. J.; McDiarmid, D. R.; McNamara, A. G.; Jones, A. Vallance; Wallis, D. D.; Cogger, L. L.

doi:10.1007/bf00751349

Cited by 172 publications

(113 citation statements)

References 20 publications

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“…Absorption measurements were obtained from the Canadian Space Agency's NORSTAR riometer array (Rostoker et al 1995;Danskin et al 2008) which, prior to 2005, formed part of a programme called CANOPUS. Figure 1 provides the locations of these riometers, giving their abbreviated place names.…”

Section: Riometer Measurementsmentioning

confidence: 99%

Assimilation of real-time riometer measurements into models of 30 MHz polar cap absorption

Rogers

Honary

2015

J. Space Weather Space Clim.

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Space weather events may adversely affect high frequency (HF) radio propagation, hence the ability to provide nowcasting and forecasting of HF radio absorption is key for industries that rely on HF communications. This paper presents methods of assimilating 30 MHz radio absorption measurements into two types of ionospheric polar cap absorption (PCA) model to improve their performance as nowcasting tools. Type 1 models calculate absorption as m times the square root of the flux of solar protons above an energy threshold, E t . Measurements from 14 riometers during 94 solar proton events (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) are assimilated by optimising the day and night values of m by linear regression. Further non-linear optimisations are demonstrated in which parameters such as E t are also optimised and additional terms characterise local time and seasonal variations. These optimisations reduce RMS errors by up to 36%. Type 2 models incorporate altitude profiles of electron and neutral densities and electron temperatures. Here the scale height of the effective recombination coefficient profile in the D-region is optimised by regression. Furthermore, two published models of the rigidity cut-off latitude (CL) are assessed by comparison with riometer measurements. A small improvement in performance is observed by introducing a 3-h lag in the geomagnetic index K p in the CL models. Assimilating data from a single riometer in the polar cap reduces RMS errors below 1 dB with less than 0.2 dB bias. However, many highlatitude riometers now provide absorption measurements in near-real time and we demonstrate how these data may be assimilated by fitting a low-order spherical harmonic function to both the measurements and a PCA model with optimised parameters.

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Section: Riometer Measurementsmentioning

confidence: 99%

Assimilation of real-time riometer measurements into models of 30 MHz polar cap absorption

Rogers

Honary

2015

J. Space Weather Space Clim.

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“…Ground-based magnetic field measurements from Canadiansector stations of the CANOPUS array (Rostoker et al, 1995) indicated dayside magnetic activity probably associated with the growth, expansion, and recovery phases of a magnetospheric substorm prior to the interval of interest. An in-depth investigation of the auroral and ionospheric dynamics associated with this event is beyond the scope of this study, and these data are therefore omitted for brevity.…”

Section: Overview Of Ionospheric and Magnetospheric Dynamicsmentioning

confidence: 99%

The location of the open-closed magnetic field line boundary in the dawn sector auroral ionosphere

et al. 2004

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Abstract. As a measure of the degree of coupling between the solar wind-magnetosphere-ionosphere systems, the rate at which the size of the polar cap (the region corresponding to ionospheric termini of open magnetic flux tubes) varies is of prime importance. However, a reliable technique by which the extent of the polar cap might be routinely monitored has yet to be developed. Current techniques provide particularly ambiguous indications of the polar cap boundary in the dawn sector. We present a case study of spaceand ground-based observations of the dawn-sector auroral zone and attempt to determine the location of the polar cap boundary using multi-wavelength observations of the ultraviolet aurora (made by the IMAGE FUV imager), precipitating particle measurements (recorded by the FAST, DMSP, and Cluster 1 and 3 satellites), and SuperDARN HF radar observations of the ionospheric Doppler spectral width boundary. We conclude that in the dawn sector, during the interval presented, neither the poleward edge of the wideband auroral UV emission (140-180 nm) nor the Doppler spectral width boundary were trustworthy indicators of the polar cap boundary location, while narrow band UV emissions in the range 130-140 nm appear to be much more reliable.

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“…The images of the ultraviolet aurora (not shown) display weak auroral activity on the nightside before 12:00 UT. The CANOPUS magnetometer (Rostoker et al, 1995) at the Dawson City station (magnetic latitude 66.06 N; magnetic longitude: À88:68 E) is located in the midnight sector (between 2300 and 0100 MLT). The magnetometer measured intervals of light Pi2 band activity during the day; the ground magnetic de¯ections ®ltered between 20 and 200 s, measured from 09:00 to 15:00 UT, are shown in Fig.…”

Section: Cross-polar Cap Potential DI Erence and Reconnection Voltagementioning

confidence: 99%

Two-dimensional electric field measurements in the ionospheric footprint of a flux transfer event

2000

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Abstract. Line-of-sight Doppler velocities from the SuperDARN CUTLASS HF radar pair have been combined to produce the ®rst two-dimensional vector measurements of the convection pattern throughout the ionospheric footprint of a¯ux transfer event (a pulsed ionospheric¯ow, or PIF). Very stable and moderate interplanetary magnetic ®eld conditions, along with a preceding prolonged period of northward interplanetary magnetic ®eld, allow a detailed study of the spatial and the temporal evolution of the ionospheric response to magnetic reconnection. The¯ux tube footprint is tracked for half an hour across six hours of local time in the auroral zone, from magnetic local noon to dusk. The motion of the footprint of the newly reconnected ux tube is compared with the ionospheric convection velocity. Two primary intervals in the PIF's evolution have been determined. For the ®rst half of its lifetime in the radar ®eld of view the phase speed of the PIF is highly variable and the mean speed is nearly twice the ionospheric convection speed. For the ®nal half of its lifetime the phase velocity becomes much less variable and slows down to the ionospheric convection velocity. The evolution of the¯ux tube in the magnetosphere has been studied using magnetic ®eld, magnetopause and magnetosheath models. The data are consistent with an interval of azimuthally propagating magnetopause reconnection, in a manner consonant with a peeling of magnetic¯ux from the magnetopause, followed by an interval of anti-sunward convection of reconnected¯ux tubes.

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Canopus ? A ground-based instrument array for remote sensing the high latitude ionosphere during the ISTP/GGS program

Cited by 172 publications

References 20 publications

Assimilation of real-time riometer measurements into models of 30 MHz polar cap absorption

Assimilation of real-time riometer measurements into models of 30 MHz polar cap absorption

The location of the open-closed magnetic field line boundary in the dawn sector auroral ionosphere

Two-dimensional electric field measurements in the ionospheric footprint of a flux transfer event

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