Determination of the running quiet daily geomagnetic variation

Janzhura, Alexander; Трошичев, О. А.

doi:10.1016/j.jastp.2007.11.004

Cited by 44 publications

(68 citation statements)

References 4 publications

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“…At high latitudes (above 60°magnetic latitudes), the geomagnetic field is almost always disturbed and a visual inspection of the data is recommended for the selection of quiet days. Some authors have developed automated techniques to determine high-latitude Sq variations (e.g., Janzhura and Troshichev 2008;Stauning 2011).…”

Section: Selection Of Quiet Daysmentioning

confidence: 99%

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

2016

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A record of the geomagnetic field on the ground sometimes shows smooth daily variations on the order of a few tens of nano teslas. These daily variations, commonly known as Sq, are caused by electric currents of several μA/m 2 flowing on the sunlit side of the Eregion ionosphere at about 90-150 km heights. We review advances in our understanding of the geomagnetic daily variation and its source ionospheric currents during the past 75 years. Observations and existing theories are first outlined as background knowledge for the nonspecialist. Data analysis methods, such as spherical harmonic analysis, are then described in detail. Various aspects of the geomagnetic daily variation are discussed and interpreted using these results. Finally, remaining issues are highlighted to provide possible directions for future work.

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Section: Selection Of Quiet Daysmentioning

confidence: 99%

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

2016

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“…Troshichev et al (2006) suggested calculating the PC index in quasi-real time. With this aim, a special procedure was elaborated to determine for each day the quiet daily curve (QDC) used as a line of reference for values of the ground magnetic disturbance (see description in Janzhura and Troshichev, 2008). The procedure of QDC derivation implies consideration of the quiet magnetic field for quiet days or quiet periods for different days provided that the quiet times are related to a single level of reference.…”

Section: Identification Of the Ss Effect By The Ground Magnetic Data mentioning

confidence: 99%

“…The main issue which is distinctly delineated in McCreadie and Menvielle (2010) is the question about the level of reference when estimating the magnetic disturbances value since other differences in the techniques are of secondary importance. The procedure applied in AARI takes into account the quiet daily curve (QDC) which is estimated for each day (see Janzhura and Troshichev, 2008). A method of calculating a running QDC makes it possible to determine a quiet daily variation even for magnetically disturbed days during solar maximum epochs and, correspondingly, to calculate the PC index in a quasi-real time regime.…”

Section: Introductionmentioning

confidence: 99%

“…One important detail in the procedure of the QDC derivation, which was not highlighted in Janzura and Troshichev (2008) and thus was not mentioned in McCreadie and Meanvielle (2010), is a problem of allowance for sector structure effects. The term "sector structure" (SS) denotes separation of the large-scale solar wind structure on an even number of sectors with opposite polarity of the interplanetary magnetic field (IMF) radial B x component.…”

Section: Introductionmentioning

confidence: 99%

“…This is not a serious problem if the analysis is carried out postfactum, based on long series of the ground magnetic observations and the IMF data obtained from spacecraft. However, the task turns out to be nontrivial while monitoring the actual magnetic activity, when the quiet daily curve (QDC) should be derived in quasi-real time (see Janzhura and Troshichev, 2008). In addition, as we see in Fig.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Identification of the IMF sector structure in near-real time by ground magnetic data

Janzhura

Трошичев

2011

Ann. Geophys.

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Abstract.A method is proposed to determine in near-real time the interplanetary magnetic field (IMF) sector structure (SS) effect on geomagnetic data from polar cap stations. To separate the SS effect, whose polarity is invariant within an interval from some days to 2 weeks, from the disturbed solar wind effects with periodicity from minutes to hours, the daily median values of geomagnetic H (or D) component are estimated. Then the median values for 9 days preceding the current day are subjected to 3-days running averages and the interpolation procedure is applied to these smoothed averages.

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The Polar Cap (PC) index: invalid index series and a different approach.

Stauning

2020

Preprint

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The Polar Cap (PC) indices are derived from the magnetic variations generated by the transpolar convection of magnetospheric plasma and embedded magnetic fields driven by the interaction with the solar wind. The PC indices are potentially very useful for space weather monitoring and forecasts and for related research. However, this study suggests that the PC index series in the near-real-time and final versions endorsed by the International Association for Geomagnetism and Aeronomy (IAGA) are invalid and unreliable. Both versions include solar wind sector (SWS) effects in the calculation of the reference levels from which magnetic disturbances are measured. The SWS effects are caused by current systems in the dayside Cusp region related to the Y-component, B Y , of the interplanetary magnetic field (IMF). However, the IAGA-endorsed handling of SWS effects may generate unfounded PC index changes of up to 4 mV/m at the nightside away from the Cusp. For the real-time PCN and PCS indices, the cubic spline-based reference level construction may cause additional unjustified index excursions of more than 3 mV/m with respect to the corresponding final index values. Noting that PC index values above 2 mV/m indicate geomagnetic storm conditions, such unjustified contributions invalidate the PC index series and prove the IAGA-endorsed derivation methods erroneous. Alternative derivation methods are shown to provide more consistent index reference levels for both final and real-time PC indices, to reduce their unfounded excursions, and to significantly increase their reliability.

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Determination of the running quiet daily geomagnetic variation

Cited by 44 publications

References 4 publications

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

Identification of the IMF sector structure in near-real time by ground magnetic data

The Polar Cap (PC) index: invalid index series and a different approach.

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