Details

Autor(en) / Beteiligte

• Ma, Yu‐Zhang
• Zhang, Qing‐He
• Lyons, Larry
• Oksavik, Kjellmar
• Xing, Zan‐Yang
• Hairston, Marc
• Nanan, Balan
• Hu, Ze‐Jun
• Wang, Yong
• Zhao, Si‐Han

Titel

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

Ist Teil von

• Journal of geophysical research. Space physics, 2023-06, Vol.128 (6), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2023

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• 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. Plain Language Summary The polar cap hot patch is a high‐density ionospheric irregularity with enhanced electron temperature and particle precipitation. The density source and associated auroral emission of the hot patch are not clear. The relationship between the hot dense plasma (hot patch) and classical polar cap patch (cold patch) is a lingering question. In this paper, we show two hot dense plasma and cold patch events using multi‐instrument observations. Two density sources are suggested: dense plasma in the lower latitude sunlit region, and plasma ionized by particle precipitation in the duskside auroral oval. Our study shows the hot dense plasma is associated with stronger aurora emissions and higher E region density in the cusp region, followed by no auroral emission (colder electron temperature) as the hot dense plasma drifts poleward and turns into a cold patch in the polar cap. It suggests that the hot dense plasma and cold patch may be different states of the same irregularity structure. Key Points The different plasma characteristics of hot dense plasma and cold patch in the polar cap are investigated using multi‐instrument observations Both hot dense plasma and cold patches are associated with auroral forms, which are located further equatorward in the cusp region The hot dense plasma and cold patch may represent different energy states of the same plasma structure as it traverses the polar ionosphere