Polar cap index as a proxy for hemispheric Joule heating

Chun, F. K.; Knipp, D. J.; McHarg, M. G.; Lu, G.; Emery, B. A.; Vennerstrøm, S.; Трошичев, О. А.

doi:10.1029/1999gl900196

Cited by 80 publications

(82 citation statements)

References 19 publications

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“…With moderately southward IMF, the total ionospheric heating in both hemispheres is several hundred gigawatts (GW) [Chun et al, 1999[Chun et al, , 2002McHarg et al, 2005], and during major geomagnetic storm periods the heating may exceed 1000 GW [Lu et al, 1998]. The result is that the thermosphere expands upward, creating additional drag on objects in low Earth orbit (LEO).…”

Section: Introductionmentioning

confidence: 99%

Predicting global average thermospheric temperature changes resulting from auroral heating

et al. 2011

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[1] The total Poynting flux flowing into both polar hemispheres as a function of time, computed with an empirical model, is compared with measurements of neutral densities in the thermosphere at two altitudes obtained from accelerometers on the CHAMP and GRACE satellites. The Jacchia-Bowman 2008 empirical thermospheric density model (JB2008) is used to facilitate the comparison. This model calculates a background level for the "global nighttime minimum exospheric temperature," T c , from solar indices. Corrections to this background level due to auroral heating, DT c , are presently computed from the Dst index. A proxy measurement of this temperature difference, DT c , is obtained by matching the CHAMP and GRACE density measurements with the JB2008 model. Through the use of a differential equation, the DT c correction can be predicted from IMF values. The resulting calculations correlate very well with the orbit-averaged measurements of DT c , and correlate better than the values derived from Dst. Results indicate that the thermosphere cools faster following time periods with greater ionospheric heating. The enhanced cooling is likely due to nitric oxide (NO) that is produced at a higher rate in proportion to the ionospheric heating, and this effect is simulated in the differential equations. As the DT c temperature correction from this model can be used as a direct substitute for the Dst-derived correction that is now used in JB200, it could be possible to predict DT c with greater accuracy and lead time.

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Section: Introductionmentioning

confidence: 99%

Predicting global average thermospheric temperature changes resulting from auroral heating

et al. 2011

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“…Further attempts to calculate Joule heating include estimates of Joule heating in response to IMF input based on largescale modelling of electrodynamic parameters (e.g., Chun et al, 1999Chun et al, , 2002Weimer, 2005;Weimer et al, 2011).…”

Section: Relations Between Pc Indices and Joule And Auroral Particle mentioning

confidence: 99%

The Polar Cap PC Indices: Relations to Solar Wind and Global Disturbances

Stauning¹

2012

Exploring the Solar Wind

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“…Troshichev et al, 2006), solar wind pressure pulses (Lukianova, 2003;Huang, 2005), cross polar cap voltage and polar cap diameter (Troshichev et al, 1996(Troshichev et al, , 2000Ridley and Kihn, 2004), ionospheric Joule heating (Chun et al, 1999(Chun et al, , 2002, and general polar cap dynamics (Stauning et al, 2008;Fiori et al, 2009;Gao et al, 2012). The PC indices were also used to predict auroral electrojet intensities (Vennerstrøm et al, 1991;Vassiliadis et al, 1996;Takalo and Timonen, 1999), global auroral power (Liou et al, 2003), and ring current intensities (Stauning et al, 2008, Troshichev et al, 2011b.…”

Section: Introductionmentioning

confidence: 99%

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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Polar cap index as a proxy for hemispheric Joule heating

Cited by 80 publications

References 19 publications

Predicting global average thermospheric temperature changes resulting from auroral heating

Predicting global average thermospheric temperature changes resulting from auroral heating

The Polar Cap PC Indices: Relations to Solar Wind and Global Disturbances

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

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