Different Methods to Determine the Polar Cap Area.

Мишин, В. М.; Bazarzhapov, A. D.; Saifudinova, T. I.; Lunyushkin, S. B.; Shirapov, D. Sh.; Woch, J.; Eliasson, L.; Opgenoorth, H. J.; Murphree, J. S.

doi:10.5636/jgg.44.1207

Cited by 17 publications

(10 citation statements)

References 17 publications

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“…The location of the OCB can be best estimated from measurements of particle precipitation boundaries (PPB) made by satellites in low-altitude orbits (e.g., Vampola, 1971;Makita et al, 1983;Makita and Meng, 1984;Newell et al, 1991;Mishin et al, 1992;Newell et al, 1996;Sotirelis and Newell, 2000). However, whilst these PPBs are considered to provide the best proxy of the OCB, they typically provide only infrequent, point measurements of this boundary.…”

Section: Introductionmentioning

confidence: 99%

Estimating the location of the open-closed magnetic field line boundary from auroral images

et al. 2010

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Abstract. The open-closed magnetic field line boundary (OCB) delimits the region of open magnetic flux forming the polar cap in the Earth's ionosphere. We present a reliable, automated method for determining the location of the poleward auroral luminosity boundary (PALB) from far ultraviolet (FUV) images of the aurora, which we use as a proxy for the OCB. This technique models latitudinal profiles of auroral luminosity as both a single and double Gaussian function with a quadratic background to produce estimates of the PALB without prior knowledge of the level of auroral activity or of the presence of bifurcation in the auroral oval. We have applied this technique to FUV images recorded by the IMAGE satellite from May 2000 until August 2002 to produce a database of over a million PALB location estimates, which is freely available to download. From this database, we assess and illustrate the accuracy and reliability of this technique during varying geomagnetic conditions. We find that up to 35% of our PALB estimates are made from double Gaussian fits to latitudinal intensity profiles, in preference to single Gaussian fits, in nightside magnetic local time (MLT) sectors. The accuracy of our PALBs as a proxy for the location of the OCB is evaluated by comparison with particle precipitation boundary (PPB) proxies from the DMSP satellites. We demonstrate the value of this technique in estimating the total rate of magnetic reconnection from the time variation of the polar cap area calculated from our OCB estimates.

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Section: Introductionmentioning

confidence: 99%

Estimating the location of the open-closed magnetic field line boundary from auroral images

et al. 2010

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“…Cowley et al (1991b) fitted all these into one simple theoretical paradigm using a dipole-plus-uniform field model to stimulate the effect of asymmetric addition of open flux to the tail lobes (Gosling et al, 1990b). The BY-dependent shift of the region of open flux was clearly demonstrated in Viking UV images by and was also seen in convection patterns from magneto gram inversion by Mishin et al (1992c). Other asymmetries which are well-explained are the BY component of the subsolar field, the MLT of the cusp (confirmed by , the MLT of the convection 'throat' (oppositely shifted to the cusp because of the Svalgard-Mansurav effect on newly-opened field lines); and the dominant sense of the cusp field-aligned currents.…”

Section: (8-iii) Imf B) Assymetriesmentioning

confidence: 82%

“…As a check of the assumptions, the difference in the dayside and nightside voltages deduced must predict the change in the polar cap area. Various methods for calculating the area of the polar cap were compared by Mishin et al (1992c).…”

Section: Measurement Techniquesmentioning

confidence: 99%

Large-scale fields and flows in the magnetosphere-ionosphere system

Lockwood

1995

Surv Geophys

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“…A number of techniques exist to estimate the location of the OCB and, hence, track the net reconnection rate in the magnetosphere. The most reliable proxies for the location of the OCB are considered to be particle precipitation boundaries measured by satellites in low‐altitude orbits, such as those of the Defense Meteorological Satellites Program [e.g., Vampola , ; Makita et al , ; Makita and Meng , ; Newell et al , ; Mishin et al , ; Newell et al , ; Sotirelis and Newell , ]. However, these yield only two‐point measurements of the OCB in each hemisphere in each 100 min orbit of the satellite, making these instruments unsuitable for tracking the detailed motion of the OCB.…”

Section: Introductionmentioning

confidence: 99%

Magnetic local time variation and scaling of poleward auroral boundary dynamics

2014

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The balance of dayside and nightside reconnection processes within the Earth's magnetosphere and its effect on the amount of open magnetic flux threading the ionosphere is well understood in terms of the expanding-contracting polar cap model. However, the nature and character of the consequential fluctuations in the polar cap boundary are poorly understood. By using the poleward auroral luminosity boundary (PALB), as measured by the FUV instrument of the IMAGE spacecraft, as a proxy for the polar cap boundary, we have studied the motion of this boundary for more than 2 years across the complete range of magnetic local time. Our results show that the dayside PALB dynamics are broadly self-similar on timescales of 12 min to 6 h and appear to be monofractal. Similarity with the characteristics of solar wind and interplanetary magnetic field variability suggests that this dayside monofractal behavior is predominantly inherited from the solar wind via the reconnection process. The nightside PALB dynamics exhibit scale-free behavior at intermediate time scales (12-90 min) and appear to be multifractal. We propose that this character is a result of the intermittent multifractal structure of magnetotail reconnection.

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Different Methods to Determine the Polar Cap Area.

Cited by 17 publications

References 17 publications

Estimating the location of the open-closed magnetic field line boundary from auroral images

Estimating the location of the open-closed magnetic field line boundary from auroral images

Large-scale fields and flows in the magnetosphere-ionosphere system

Magnetic local time variation and scaling of poleward auroral boundary dynamics

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