Storm phase–partitioned rates and budgets of global Alfvénic energy deposition, electron precipitation, and ion outflow

Hatch, Spencer; LaBelle, J.; Chaston, C. C.

doi:10.1016/j.jastp.2017.08.009

Cited by 12 publications

(16 citation statements)

References 56 publications

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“…Their global spatial distributions [Figs. 2A and B of ( 25 )] of Alfvén waves and Alfvénic electrons during nonstorm and storm periods are morphologically remarkably similar to the here-reported Poynting flux distributions above the AAR during similar geomagnetic conditions. While this morphological similarity suggests causal connections, with the high-altitude Alfvén waves being the driver of the low-altitude signatures, it assumes an energy transfer scenario inside the AAR that has been reviewed by ( 12 ), even though some details are still awaiting observational confirmation.…”

Section: Discussionsupporting

confidence: 82%

“…From their global distributions, Hatch et al . ( 25 ) calculated, in a similar fashion as was done here, the total integrated energy rates recorded below the AAR for nonstorm periods, storm main phase, and storm recovery phase. For comparison, we reproduced the FAST-based values together with our results in Table 1.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, it is noted that Hatch et al . ( 25 ) did not specify the flow direction of the low-altitude Alfvén waves, which leaves it open to whether the waves traveled exclusively downward or existed as a mixture of downward- and upward-traveling waves. This would affect the energy balance as well.…”

Section: Discussionmentioning

confidence: 99%

“…*Polar study period: January 1997 to December 2002.†Net deposition at Polar is not necessarily the true deposition below the AAR (see text for explanation).‡FAST study period: October 1996 to November 1999 [from ( 25 )].§Calculated under the assumption that all Alfvén wave power at FAST flows toward the ionosphere (i.e., no upflowing Alfvénic power).…”

Section: Discussionmentioning

confidence: 99%

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Assessing the global Alfvén wave power flow into and out of the auroral acceleration region during geomagnetic storms

et al. 2019

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Geomagnetic storms are large space weather events with potentially tremendous societal implications. During these storms, the transfer of energy from the solar wind into geospace is largely increased, leading to enhanced energy flow and deposition within the magnetosphere and ionosphere. While various energy forms participate, the rate of total Alfvén wave energy flowing into the auroral acceleration region—where the magnetosphere and ionosphere couple—has not been quantified. Here, we report a fourfold increase in hemispherical Alfvénic power (from 2.59 to 10.05 GW) over a largely expanded oval band covering all longitudes and latitudes between 50° and 85° during the main storm phase compared with nonstorm periods. The Poynting flux associated with individual Alfvén waves reached values of up to about 0.5 W/m2 (mapped to ionospheric altitude). These results demonstrate that Alfvén waves are an important component of geomagnetic storms and associated energy flow into the auroral acceleration region.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Assessing the global Alfvén wave power flow into and out of the auroral acceleration region during geomagnetic storms

et al. 2019

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“…In extensive studies of storm-time and IMF effects on wave energy transport and deposition, Hatch et al [2016;2018] developed an algorithm for identification of inertial Alfvén waves (IAWs) observed by FAST while operating in "fast survey" mode. The algorithm, which is derived from that employed by Chaston et al [2003;2007], begins by examining the slope of the cross-track (approximately east-west) component of the magnetic field measured by the fluxgate magnetometer to obtain an estimate of the field-aligned current J mag .…”

Section: Data Presentationmentioning

confidence: 99%

Application of a new method for calculation of low-frequency wave vectors

Hatch¹,

LaBelle²

2018

Planetary Radio Emissions Viii

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The problem of resolving spatial and temporal properties of waves, so-called "space-time ambiguity", is a longstanding issue of single-spacecraft measurements. The general case can be insoluble, but in special cases in which certain assumptions hold, such as when each frequency corresponds to a single wave vector, the ambiguity can be resolved. Recently a method has been proposed to obtain wave vectors from single-spacecraft measurements of Alfvén wave-modulated magnetic fields and currents [Bellan, 2016], through application of the Wiener-Khinchin theorem to cross-correlation of the current density J and magnetic field B, and to the autocorrelation of B. We apply this method to spacecraft data, obtained by culling, from a large database of inertial Alfvén waves observed by the FAST satellite, two case study intervals during which extraordinarily large modulated currents were measured by the FAST particle detectors in burst mode. Results of this analysis for at least one of the two case studies appear consistent with known properties of ionospheric inertial Alfvén waves and pass error and consistency checks within the analysis method.

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