The Polar Cap index: A critical review of methods and a new approach

Stauning, P.

doi:10.1002/jgra.50462

Cited by 53 publications

(62 citation statements)

References 71 publications

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“…The effects from reverse convection events on the regression are illustrated in Fig. 11a and b of Stauning (2013b). The effects are particularly strong at daytime in the summer season and much larger for Thule than for Vostok due to the larger frequency and strength of reverse convection events in the northern polar cap compared to the southern.…”

Section: Comparison Of Pcn and Pcs Regression Coefficientsmentioning

confidence: 97%

“…In summary (cf. Stauning, 2013b), the PC index is based on an assumed linear relation between E M , the "geo-effective" (or "merging") electric field in the solar wind encountering the Earth, and F PROJ , the polar cap horizontal magnetic variation (at ground) projected to the so-called "optimum direction".…”

Section: Pc Index Definitionmentioning

confidence: 99%

“…The DMI version in blue line is based on data from 1997 to 2009 excluding strong reverse convection events. A similar figure without the IAGAendorsed parameters and using a different epoch for the DMI coefficients is provided in Stauning (2013b). Vostok, and OMNI 1997(ex.…”

Section: Comparison Of Pcn and Pcs Regression Coefficientsmentioning

confidence: 99%

“…In the past there have been seven different versions of the PCN index and five versions of the PCS index (see Stauning, 2013b). The new PC index version endorsed by IAGA in 2013 and published at http://pc-index.org is supplied jointly by Arctic and Antarctic Research Institute (AARI), Russia, and DTU Space, Denmark.…”

Section: Introductionmentioning

confidence: 99%

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A critical note on the IAGA-endorsed Polar Cap index procedure: effects of solar wind sector structure and reverse polar convection

Stauning

2015

Ann. Geophys.

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Abstract. The International Association of Geomagnetism and Aeronomy (IAGA) has recently endorsed a new Polar Cap (PC) index version to supersede the previous seven different versions of the PCN (North) index and the five different PCS (South) index versions. However, the new PC index has some adverse features which should be known and taken into account by users of the index. It uses in its derivation procedure an "effective" quiet day level (QDC) composed of a "basic" QDC and an added solar wind sector term related to the azimuthal component (B y ) of the interplanetary magnetic field (IMF). The added IMF B y -related terms may introduce unjustified contributions to the PC index of more than 2 index units (mV m −1 ). Furthermore, cases of reverse convection during strong northward IMF B z (NBZ) conditions included in the database for calculation of index coefficients can cause unjustified index enhancements of 0.5-1 mV m −1 during calm conditions, reduction of index values by more than 20 % during disturbed conditions, and inconsistencies between index coefficients and index values for the northern and southern polar caps. The aim here is to specify these adverse features and quantify their effects, and to suggest alternative steps for future modifications of the index procedure.

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Section: Comparison Of Pcn and Pcs Regression Coefficientsmentioning

confidence: 97%

Section: Pc Index Definitionmentioning

confidence: 99%

Section: Comparison Of Pcn and Pcs Regression Coefficientsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A critical note on the IAGA-endorsed Polar Cap index procedure: effects of solar wind sector structure and reverse polar convection

Stauning

2015

Ann. Geophys.

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“…They have important applications for space weather analyses and forecasting and have been used in many publications (e.g. Stauning, 2013a, and references therein). The PC indices could be used, among others, to indicate the energy transfer from the solar wind to the magnetosphereionosphere-thermosphere system (e.g.…”

Section: Introductionmentioning

confidence: 99%

A critical note on the IAGA-endorsed Polar Cap (PC) indices: excessive excursions in the real-time index values

Stauning

2018

Ann. Geophys.

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Abstract. The Polar Cap (PC) indices were approved by the International Association for Geomagnetism and Aeronomy (IAGA) in 2013 and made available at the web portal http://pcindex.org holding prompt (real-time) as well as archival index values. The present note provides the first reported examination of the validity of the IAGA-endorsed method to generate real-time PC index values. It is demonstrated that features of the derivation procedure defined by Janzhura and Troshichev (2011) may cause considerable excursions in the real-time PC index values compared to the final index values. In examples based on occasional downloads of index values, the differences between real-time and final values of PC indices were found to exceed 3 mV m −1 , which is a magnitude level that may indicate (or hide) strong magnetic storm activity.

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Canonical correlation analysis of the combined solar wind and geomagnetic index data sets

Borovsky

2014

JGR Space Physics

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Canonical correlation analysis (CCA) will evaluate the degree of correlation between two multivariate data sets and will uncover patterns of correlation between the two data sets. Here CCA is applied to the multivariate solar wind data set and the multivariate geomagnetic index data set. CCA creates a new set of solar wind variables and a new set of Earth variables. The first of the new solar wind variables can be used as a solar wind driver function for the magnetosphere; the conjugate Earth variable can be used as an Earth vector to describe global geomagnetic activity in the magnetosphere-ionosphere system. The CCA-generated driver functions are found to be superior in accuracy to other driver functions in the literature. CCA of the combined data sets provides information about (1) differences in the solar wind driving of high-latitude geomagnetic indices (AE, AU, AL, and polar cap index) versus magnetospheric-convection geomagnetic indices (Kp and midnight boundary index), (2) the properties of electric field-based driver functions versus reconnection-based driver functions, and (3) improvements to solar wind/magnetosphere correlations produced by time averaging the solar wind clock angle. The CCA process tends to focus on the magnetospheric-convective indices over other indices: this may indicate that there is more predictable variance in the global-convective indices than in the others.

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The Polar Cap index: A critical review of methods and a new approach

Cited by 53 publications

References 71 publications

A critical note on the IAGA-endorsed Polar Cap index procedure: effects of solar wind sector structure and reverse polar convection

A critical note on the IAGA-endorsed Polar Cap index procedure: effects of solar wind sector structure and reverse polar convection

A critical note on the IAGA-endorsed Polar Cap (PC) indices: excessive excursions in the real-time index values

Canonical correlation analysis of the combined solar wind and geomagnetic index data sets

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