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Obtaining Continental‐Scale, High‐Resolution 2‐D Ionospheric Flows and Application to Meso‐Scale Flow Science.

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Title: Obtaining Continental‐Scale, High‐Resolution 2‐D Ionospheric Flows and Application to Meso‐Scale Flow Science.
Authors: Nishimura, Y.1 (AUTHOR) toshi16@bu.edu, Lyons, L. R.2 (AUTHOR), Deng, Y.3 (AUTHOR), Sheng, C.3 (AUTHOR), Bristow, W. A.4 (AUTHOR), Donovan, E. F.5 (AUTHOR), Angelopoulos, V.6 (AUTHOR), Nishitani, N.7 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. Aug2024, Vol. 129 Issue 8, p1-17. 17p.
Subject Terms: *Ionosphere, Shear flow, Channel flow, Meteorological satellites, Auroras
Abstract: An approach for creating continental‐scale, multi‐scale plasma convection maps in the nightside high‐latitude ionosphere using the spherical elementary current systems technique has been developed and evaluated. The capability to reconstruct meso‐scale flow channels improved dramatically, and the velocity errors were reduced by ∼30% compared to the spherical harmonic fitting method. Uncertainties of velocity vectors estimated by varying the model setup was also low. Convection maps for a substorm event revealed multiple flow channels in the polar cap, dominating the convection in the quiet time and early growth phase. The meso‐scale flows extended toward the nightside auroral oval and had continuous flow channels over >20° of latitude, and the flow channels dynamically merged and bifurcated. The substorm onset occurred along one of the flow channels, and the azimuthal extent of the enhanced flows coincided with the initial width of the auroral breakup. During the expansion phase, the meso‐scale flows repetitively crossed the oval poleward boundary, and some of them contributed to subauroral polarization streams enhancements. Increased flows extended duskward, along with the westward traveling surge. Then, flows near midnight weakened and evolved to the Harang flow shear. The meso‐scale flow channels had significant (∼10%–40% on average) contributions to the total plasma transport. The meso‐scale flows were highly variable on ∼10 min time scales and their individual maximum contributions reached upto 73%. These results demonstrate the capability of specifying realistic convection patterns, quantifying the contribution of meso‐scale transport, and evaluating the relationship between meso‐scale flows and localized auroral forms. Key Points: High‐resolution convection maps in the nightside high‐latitude ionosphere were created with small errors and good agreement with Defense Meteorological Satellite ProgramThe convection maps revealed a dynamic interplay of multiple flow channels during a substorm, including precursor flows to substorm onsetThe meso‐scale flows contribute to ∼10%–40% of the total flows on average. The contribution increases up to 73% during flow bursts [ABSTRACT FROM AUTHOR]
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Abstract:An approach for creating continental‐scale, multi‐scale plasma convection maps in the nightside high‐latitude ionosphere using the spherical elementary current systems technique has been developed and evaluated. The capability to reconstruct meso‐scale flow channels improved dramatically, and the velocity errors were reduced by ∼30% compared to the spherical harmonic fitting method. Uncertainties of velocity vectors estimated by varying the model setup was also low. Convection maps for a substorm event revealed multiple flow channels in the polar cap, dominating the convection in the quiet time and early growth phase. The meso‐scale flows extended toward the nightside auroral oval and had continuous flow channels over >20° of latitude, and the flow channels dynamically merged and bifurcated. The substorm onset occurred along one of the flow channels, and the azimuthal extent of the enhanced flows coincided with the initial width of the auroral breakup. During the expansion phase, the meso‐scale flows repetitively crossed the oval poleward boundary, and some of them contributed to subauroral polarization streams enhancements. Increased flows extended duskward, along with the westward traveling surge. Then, flows near midnight weakened and evolved to the Harang flow shear. The meso‐scale flow channels had significant (∼10%–40% on average) contributions to the total plasma transport. The meso‐scale flows were highly variable on ∼10 min time scales and their individual maximum contributions reached upto 73%. These results demonstrate the capability of specifying realistic convection patterns, quantifying the contribution of meso‐scale transport, and evaluating the relationship between meso‐scale flows and localized auroral forms. Key Points: High‐resolution convection maps in the nightside high‐latitude ionosphere were created with small errors and good agreement with Defense Meteorological Satellite ProgramThe convection maps revealed a dynamic interplay of multiple flow channels during a substorm, including precursor flows to substorm onsetThe meso‐scale flows contribute to ∼10%–40% of the total flows on average. The contribution increases up to 73% during flow bursts [ABSTRACT FROM AUTHOR]
ISSN:21699380
DOI:10.1029/2024JA032924