Combined ESR and EISCAT observations of the dayside polar cap and auroral oval during the May 15, 1997 storm

Liu, Hong; Schlegel, K.; Ma, Shuang‐Gang

doi:10.1007/s00585-000-1067-x

Cited by 12 publications

(11 citation statements)

References 14 publications

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“…It could be related to the following. Despite the fact that there is energy input of the penetration of the electric field, which can cause joule heating in the ionosphere (Liu et al, 2000), there has been speculation about an additional source of energy at lower latitudes during disturbances. In particular, Noël and Pröllss (1993) suggested that heating by a neutralized ring current could be the possible heat source at equatorial and tropical latitudes.…”

Section: Discussionmentioning

confidence: 99%

The Southern Hemisphere and equatorial region ionization response for a 22 September 1999 severe magnetic storm

2004

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Abstract. The ionospheric storm evolution process was monitored during the 22 September 1999 magnetic storm over the Australian eastern region, through measurements of the ionospheric Total Electron Content (TEC) from seven Global Positioning Systems (GPS) stations. The spatial and temporal variations of the ionosphere were analysed as a time series of TEC maps. Results of our analysis show that the main ionospheric effect of the storm under consideration are: the long lasting negative storm effect during a magnetic storm at mid-latitude regions; the strong, positive disturbances during the storm's main phase at auroral latitude regions; the effects of storm-induced equatorward directed wind causing a positive disturbance at high and mid-latitude stations with appropriate time shift between higher and lower latitudes; daytime poleward movement of depleted plasma that causes temporary suppression of the equatorial anomaly during the start of the storm recovery phase; and prompt penetration of eastward electric fields to ionospheric altitudes and the production of nearly simultaneous TEC enhancement at all latitudes. In general, we found dominant negative disturbance over mid and high latitudes and positive disturbance at low latitudes. A comparison of storm-time behaviour of TEC determined from GPS satellites, and f o F 2 derived from ionosondes at a range of latitudes, showed reasonable agreement between the two independent measurements.

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Section: Discussionmentioning

confidence: 99%

The Southern Hemisphere and equatorial region ionization response for a 22 September 1999 severe magnetic storm

2004

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“…Prölss, 1995;Mikhailov and Schlegel, 1998;Liu et al, 2000). Several mechanisms could be responsible for these depletions.…”

Section: High Latitudesmentioning

confidence: 99%

Observations of the April 2002 geomagnetic storm by the global network of incoherent scatter radars

et al. 2005

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Abstract. This paper describes the ionospheric response to a geomagnetic storm beginning on 17 April 2002. We present the measurements of ionospheric parameters in the F-region obtained by the network of eight incoherent scatter radars. The main effects of this storm include a deep decrease in the electron density observed at high and middle latitudes in the pre-noon sector, and a minor enhancement in the density observed in the daytime sector at middle latitudes. Extreme plasma heating (>1000−3000 K) is observed at high latitudes, subsiding to 200-300 K at subauroral latitudes. The western hemisphere radar chain observed the prompt penetration of the electric field from auroral to equatorial latitudes, as well as the daytime enhancement of plasma drift parallel to the magnetic field line, which is related to the enhancement in the equatorward winds. We suggest that in the first several hours after the storm onset, a negative phase above Millstone Hill (pre-noon sector) results from counteracting processes -penetration electric field, meridional wind, and electrodynamic heating, with electrodynamic heating being the dominant mechanism. At the lower latitude in the prenoon sector (Arecibo and Jicamarca), the penetration electric field becomes more important, leading to a negative storm phase over Arecibo. In contrast, in the afternoon sector at mid-latitudes (Kharkov, Irkutsk), effects of penetration electric field and meridional wind do not counteract, but add up, leading to a small (∼15%), positive storm phase over these locations. As the storm develops, Millstone Hill and Irkutsk mid-latitude radars observe further depletion of electron density due to the changes in the neutral composition.

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“…We can see that enhancements in electron density around 09:10 UT and 09:50 UT are accompanied by a remarkable increase in electron temperature, suggesting their association with local soft particle precipitation. It has been shown in our previous paper (Liu et al, 2000) that these two electron enhancements are peak-to-peak correlated with a large pulselike increase in solar wind dynamic pressure by pressurecontrolled soft particle precipitation. On the other hand, there is no remarkable increase in electron temperature accompanying the "blob" between 10:40 UT to 11:10 UT.…”

Section: Evidence Of Strong Dayside Aurora Near Eiscat By Polar Uvimentioning

confidence: 53%

“…16.0 • E) were in operation and caught the storm simultaneously during its main phase at the dayside sector. In our previous paper (Liu et al, 2000), it was indicated that, according to calculations by means of the T96-01 magnetic field model (Tsy- ganeko, 1996), ESR was in the dayside polar cap during the main phase and the beginning of the recovery phase of the 15 May 1997 storm, while EISCAT was in the dayside auroral oval or on its poleward boundary, being in agreement with the UV images taken from the ultraviolet imager (UVI) on board the POLAR satellite. This provides a valuable opportunity to investigate storm effects in the dayside auroral oval and in the polar cap regions simultaneously.…”

Section: Introductionmentioning

confidence: 94%

“…This means that local particle precipitation did not cause the concerned "blob". Long-lasting large ion upflow (Liu et al, 2000) may also be a possible evidence that the positive storm at ESR is probably not attributed to local particle precipitation. These facts lead us to transportation effects due to plasma convection flow and thermospheric circulation for the positive Fregion storm at ESR.…”

Section: Evidence Of Strong Dayside Aurora Near Eiscat By Polar Uvimentioning

confidence: 99%

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Positive storm effects in the dayside polar ionospheric F-region observed by EISCAT and ESR during the magnetic storm of 15 May 1997

Cai

Liu

et al. 2002

Ann. Geophys.

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Abstract. EISCAT/ESR radar data and in situ FAST and PO-LAR satellite observations are coordinately analyzed to investigate positive ionospheric storm effects in the dayside upper F-region in both the polar cap and the auroral oval during the magnetic storm of 15 May 1997. An ionization enhancement, lasting for about 2.5 h, appeared first over the EIS-CAT site around magnetic noon; about one hour later, a similar ionization enhancement was also seen over ESR. During the concerned time period ion energy spectra measured on board FAST show clearly continuous energy-latitude dispersion when the satellite passed by over the EISCAT latitude. This implies that EISCAT was located under the polar cusp region which was highly active, and expanded greatly equatorwards due to magnetopause reconnections during longlasting southward IMF. Simultaneously, soft particles of the magnetosheath precipitated into the F-region ionosphere and caused the positive storm effects over EISCAT. The coincident increase in electron temperature at EISCAT gives additional evidence for soft particle precipitation. Consistently, POLAR UV images show strong dayside aurora extending to as low as 62 • N magnetic latitude. The ionization enhancement over ESR, however, seems not to be caused by local particle precipitation, evidenced by a lack of enhanced electron temperature. The observed plasma convection velocity and data-fitted convection patterns by AMIE suggested that it is likely to be a polar patch originating from the cusp region and traveling to the ESR site.

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Combined ESR and EISCAT observations of the dayside polar cap and auroral oval during the May 15, 1997 storm

Cited by 12 publications

References 14 publications

The Southern Hemisphere and equatorial region ionization response for a 22 September 1999 severe magnetic storm

The Southern Hemisphere and equatorial region ionization response for a 22 September 1999 severe magnetic storm

Observations of the April 2002 geomagnetic storm by the global network of incoherent scatter radars

Positive storm effects in the dayside polar ionospheric F-region observed by EISCAT and ESR during the magnetic storm of 15 May 1997

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