The Dependence of Cold and Hot Patches on Local Plasma Transport and Particle Precipitation in Northern Hemisphere Winter

Zhang, Duan; Zhang, Q.; Ma, Y.-Z.; Oksavik, K.; Lyons, L. R.; Zou, Xing; Hairston, M. R.; Deng, Zhong-Xin; Liu, Jianjun

doi:10.1029/2022gl098671

Cited by 4 publications

(9 citation statements)

References 41 publications

(71 reference statements)

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“…This indicates that the solar extreme ultraviolet radiation (EUV) production of high‐density plasma is less likely as a plasma source of patches. The electron temperature of the patches “III” and “V” is mainly similar or slightly lower than that of the surroundings, which is characteristic of cold patches (e.g., Ma et al., 2018; Zhang et al., 2017, 2021, 2022). The other patches are more likely to be a mix of cold and hot patches.…”

Section: Observations Resultsmentioning

confidence: 98%

Do the Throat Auroras Create Polar Cap Patches?

Zhang

Oksavik

et al. 2023

Geophysical Research Letters

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Throat auroras and polar cap patches are common phenomena in the polar ionosphere resulting from solar wind-magnetosphere-ionosphere coupling. The throat aurora is a discrete aurora that is associated with localized magnetopause indentations (Han, 2019). It is usually located equatorward of the cusp aurora oval near magnetic noon, oriented in the south-north direction (Han et al., 2015) and is more frequently observed under radial interplanetary magnetic field (IMF, Bx-dominated conditions) (e.g., Han et al., 2017;Rodriguez et al., 2012). Han et al. (2016) indicated that throat aurora is an ionospheric feature in which magnetosheath particles enter the magnetosphere along open magnetic field lines, based on data from ground-based all-sky imagers (ASIs) and Magnetospheric Multiscale (MMS) satellites. Throat auroras are also observed to be accompanied by Joule heating and ion upflows, based on data from a European Incoherent Scatter (EISCAT) radar experiment (Han et al., 2019), which supports throat aurora being associated with magnetopause reconnection.The polar cap patch is another common phenomenon in the dayside ionosphere polar regions. It is also associated with transient dayside reconnection (e.g., Carlson et al., 2004;Lockwood & Carlson, 1992;Zhang et al., 2011Zhang et al., , 2013. A patch is an island of high-density F region ionospheric plasma with a typical size of

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Section: Observations Resultsmentioning

confidence: 98%

Do the Throat Auroras Create Polar Cap Patches?

Zhang

Oksavik

et al. 2023

Geophysical Research Letters

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“…(2018) and Zhang et al. (2022) suggest the hot patch is located equatorward of cold patch, and suggest the particle precipitation and transport process may dominate the hot and cold patch formation, respectively. This study claim that these mechanisms can both contribute the formation of patches.…”

Section: Discussionmentioning

confidence: 97%

A Comparative Study on the Hot Dense Plasma and Cold Patch by Using Multi‐Instrument Observations

Zhang

Lyons

et al. 2023

JGR Space Physics

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The polar cap hot patch is an enhanced density structure which is associated with particle precipitation, ion upflow and flow shears. Based on combined observations from DMSP satellites, EISCAT radar, and all‐sky imager at the Chinese Yellow River Station, the plasma characteristics and evolution of hot dense plasma and classical polar cap patch are investigated. Both of them show enhanced F region density, but the hot dense plasma is associated with higher electron temperature and enhanced E region electron density caused by particle precipitation. Compared to the cold patch, the hot dense plasma is closer to the cusp region and is associated with strong auroral emissions. Based on the joint observations, the evolution of the hot/cold dense plasma is discussed. In the initial phase the dense plasma comes from the sunlit lower latitude region, or from particle precipitation in the duskside auroral oval, and is heated locally by poleward moving auroral structures in the dayside auroral oval. Next the patches move poleward into the polar cap where a decaying electron temperature (i.e., less precipitation) gradually transform them into a cold patch.

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“…DMSP F19 observed the patch around 1425 UT, and the electron temperature of the patch was about 1,000 K higher than the ion temperature, which is called a "hot patch" (Zhang et al, 2017;Ma, Zhang, Xing, Heelis, et al, 2018;D. Zhang et al, 2021D. Zhang et al, , 2022.…”

Section: Observationmentioning

confidence: 99%

“…Note that the DMSP F18 orbit is not shown because the electron density observation from that spacecraft is unavailable. DMSP F19 observed the patch around 1425 UT, and the electron temperature of the patch was about 1,000 K higher than the ion temperature, which is called a “hot patch” (Zhang et al., 2017; Ma, Zhang, Xing, Heelis, et al., 2018; D. Zhang et al., 2021, 2022). The plasma density of the hot patch had double‐peak of about 2*10 10 m −3 associated with the soft‐electron precipitation.…”

Section: Observationmentioning

confidence: 99%

“…Cold patches (high density and lower electron temperature, Ti/Te > 0.8) are associated with the ionization by solar extreme ultraviolet (EUV) radiation at mid‐latitude, and hot patches (high density and higher electron temperature, Ti/Te < 0.8) are associated with particle precipitation. The cold patches are related to solar activity and found in the central polar cap (D. Zhang et al., 2021, 2022). The hot patches are found close to the auroral oval, associated with strong auroral emissions, ion upflows, and flow shears (e.g., Lorentzen et al., 2010; Ma et al., 2023; Nishimura et al., 2014; Zhang et al., 2023).…”

Section: Introductionmentioning

confidence: 99%

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Multi‐Instrument Observations of the Evolution of Polar Cap Patches Associated With Flow Shears and Particle Precipitation

Zhang,

Oksavik

et al. 2023

JGR Space Physics

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Simultaneous observations from Defense Meteorological Satellite Program, Swarm, Resolute Bay all‐sky imagers, GPS Total Electron Content and Super Dual Auroral Radar Network, are used to investigate the evolution and key characteristics of the Tongue of Ionization (TOI) being restructured into a polar cap patch. Six satellites crossed the TOI of patch as it moved from the dayside to the nightside. It was initially hot, then a mix of both cold and hot, and finally it became a cold patch. This suggests that cold patch is not only a result of solar extreme ultraviolet radiation, but may also develop when a hot patch cools down. Soft‐electron precipitation and flow shears both contribute to the TOI restructuring and the appearance of polar cap patch. The plasma density of patch at ∼500 km was at least 4 times higher than at ∼800 km. The plasma density enhancement gradually decreased as the patch evolved due to decreased production and transport of cold nightside low‐density plasma. Moreover, the duskward motion of the patch was influenced by changes in the ionospheric convection pattern.

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The Dependence of Cold and Hot Patches on Local Plasma Transport and Particle Precipitation in Northern Hemisphere Winter

Abstract: Polar cap patches are common phenomena in the polar ionospheric F region. They are plasma structures whose densities are at least twice that of the surrounding regions, with a typical size ranging from hundreds to thousands of kilometers (e.g.,

Cited by 4 publications

References 41 publications

Do the Throat Auroras Create Polar Cap Patches?

Do the Throat Auroras Create Polar Cap Patches?

A Comparative Study on the Hot Dense Plasma and Cold Patch by Using Multi‐Instrument Observations

Multi‐Instrument Observations of the Evolution of Polar Cap Patches Associated With Flow Shears and Particle Precipitation

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