Particle precipitation during NEIAL events: simultaneous ground based nighttime observations at Svalbard

Lunde, J.E.; Løvhaug, U. P.; Gustavsson, B.

doi:10.5194/angeo-27-2001-2009

Cited by 4 publications

(2 citation statements)

References 33 publications

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“…F region NEIAL occurrence shows another small peak at 2100 MLT in Figure 3c, and then only E region NEIALs in Figure 4b show small peaks at 2100–2200 and 0000 MLT. Such NEIALs during nighttime hours at high latitudes were reported by Lunde et al [2009], and they were associated with the substorm expansion phase on the nightside.…”

Section: Resultssupporting

confidence: 56%

On the statistical relation between ion upflow and naturally enhanced ion-acoustic lines observed with the EISCAT Svalbard radar

et al. 2011

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We have investigated characteristics of ion upflow and naturally enhanced ion‐acoustic lines (NEIALs) based on the European Incoherent Scatter (EISCAT) Svalbard radar (ESR) data continuously obtained between March 2007 and February 2008. For the ion upflow study we have used approximately 78,000 field‐aligned profiles obtained with the ESR. For the NEIAL study we have identified approximately 1500 NEIALs in the ESR data at altitudes between 100 and 500 km. The occurrence frequency of ion upflow shows two peaks, at about 0800 and 1300 magnetic local time (MLT), while only one strong peak is seen around 0900 MLT for NEIALs. The upward ion flux also has only one peak around 1100–1300 MLT. The occurrence frequency of ion upflow varies strongly over season. It is higher in winter than in summer, whereas NEIALs are more frequent in summer than in winter. NEIALs frequently occur under high geomagnetic activity and also high solar activity conditions. Approximately 10% of NEIALs in the F region ionosphere were accompanied by NEIALs in the E region (occurred at altitudes below 200 km). About half of the E region enhanced echoes did not have an F region counterpart. Upshifted NEIALs dominate in the E region whereas downshifted NEIALs are usually stronger above an altitude of 300 km. The high occurrence frequency of NEIALs in the prenoon region (0800–1000 MLT) might be associated with acceleration of thermal ions to suprathermal ones. At the same MLT and geomagnetic latitude suprathermal ions and broadband extremely low frequency (BBELF) wave activity have been observed, according to previous studies.

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Section: Resultssupporting

confidence: 56%

On the statistical relation between ion upflow and naturally enhanced ion-acoustic lines observed with the EISCAT Svalbard radar

et al. 2011

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“…Lunde et al . [] reported NEIALs associated with a substorm expansion phase on the nightside and their relation to auroral emissions with different wavelengths. They suggested that intensity enhancements in the 844.6 nm emission line could be a better candidate than the 630.0 nm emission as an optical signature for the NEIALs.…”

Section: Discussionmentioning

confidence: 99%

Relationship between auroral substorm and ion upflow in the nightside polar ionosphere

et al. 2013

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[1] We investigated ionospheric ion upflow during an auroral substorm using simultaneous European Incoherent Scatter radar and IMAGE satellite data. Approximately 6 min after an initial brightening identified with data from the IMAGE wideband imaging camera instrument, ion upflow was seen and the electron temperature became enhanced, too. The ion upflow, with a velocity of about 150 m/s, and the electron temperature enhancement lasted for about 25 min. During the poleward expansion phase, surges of large upward ion velocity and flux, and high ion and electron temperatures occurred over Longyearbyen. The upward ion flux reached 2 × 10 14 m À2 s À1. Naturally enhanced ion-acoustic lines (NEIALs) were seen near the poleward edge of the expanded auroral oval both near the end of expansion phase 17 min after onset and also later in the recovery phase. The NEIALs seemed to be accompanied by another type of enhanced echoes, obliquely to the local geomagnetic field. Data from the Low Energy Neutral Atom instrument on the IMAGE satellite show that energetic neutral oxygen reaches the IMAGE satellite about 40 min after the initial brightening, and oxygen continues to get detected during the recovery phase. We propose that ion upflow at the poleward edge of the auroral oval during the expansion phase is related to ion/neutral outflow with energy below 18-27 eV, whereas during the recovery phase of a substorm upward ions are accelerated up to about 60 eV and flow out in the entire polar region.

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Intermittency in midlatitude Pi2 pulsations observed during magnetospheric substorms and in the absence of these phenomena

Kurazhkovskaya

Klain

2010

Geomagn. Aeron.

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Particle precipitation during NEIAL events: simultaneous ground based nighttime observations at Svalbard

Cited by 4 publications

References 33 publications

On the statistical relation between ion upflow and naturally enhanced ion-acoustic lines observed with the EISCAT Svalbard radar

On the statistical relation between ion upflow and naturally enhanced ion-acoustic lines observed with the EISCAT Svalbard radar

Relationship between auroral substorm and ion upflow in the nightside polar ionosphere

Intermittency in midlatitude Pi2 pulsations observed during magnetospheric substorms and in the absence of these phenomena

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