Solar cycle and seasonal variations of the ionosphere observed with the Chatanika incoherent scatter radar

Baron, M. J.; Heinselman, C. J.; Petričeks, J.

doi:10.1029/rs018i006p00895

Cited by 17 publications

(8 citation statements)

References 5 publications

(2 reference statements)

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“…However, on the basis of the Chatanika incoherent radar observations, Baron et al. [6] found that anomalies also exist in Alaska (65.1 • N). The winter anomaly at Tromsoe (69.6 • N, 19.2 • E) was reported by Farmer et al [7] .…”

Section: Introductionmentioning

confidence: 99%

Climatologic Characteristics of High-Latitude Ionosphere-Eiscat Observations and Comparison with the Iri Model

Cai

Schlegel

2005

Chinese J. Geophys.

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With EISCAT observations during 1988~1999, the climatologic features of electron densities in the auroral ionospheric F‐region have been investigated statistically and compared with the IRI‐2001 model for different seasons at different phases of the solar cycle. The electron densities from EISCAT observations show obviously the well‐known winter anomaly in solar maximum and a semiannual variation in solar minimum. The averaged 2‐D distributions of EISCAT Ne vs. tUT and height H, as well as diurnal variations of TEC up to 500km, are reasonably consistent with those predicted by the IRI‐2001 model as a whole. The height profiles of Ne, however, are remarkably different between the IRI model and the EISCAT observations around the time when the TEC reaches its maximum. In this case the electron density above F2 peak is too large in the IRI‐2001 model, causing higher TEC than EISCAT observations. On the other hand, EISCAT observations show obviously characteristics of semiannual variation at fall phase of solar activity, however, the results of IRI‐2001 model show no evidence of that.

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Section: Introductionmentioning

confidence: 99%

Climatologic Characteristics of High-Latitude Ionosphere-Eiscat Observations and Comparison with the Iri Model

Cai

Schlegel

2005

Chinese J. Geophys.

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“…It therefore also appears inconsistent that the ionization enhancement is due to local cusp related soft particle flux. This of course assumes that the spatial extent of the cusp does not Baron et al [1983] for summer is 2.6 x 105cm -3 and the measured value was 3.0 x 105cm -3. The variation in the peak densities on the two days is also consistent with the known seasonal variations of the O-to-N 2 ratio (i.e., the winter anomaly) as discussed by Roble [1977].…”

Section: Introductionmentioning

confidence: 99%

F‐region ionospheric structure associated with antisunward flow near the dayside polar cusp

Kelly¹,

Vickrey²

1984

Geophysical Research Letters

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After one year of measurements using the Sondrestrom incoherent‐scatter radar (74° Λ), a number of repeatable features have been identified that interrelate the F‐region ionization and plasma convection patterns. One of these is an extended (poleward) ridge of ionization frequently present overhead near magnetic local noon. This ionization enhancement is associated with large ion drift velocities with a significant poleward component. Similar ionization features have been reported and thought to be produced by convection of F layer plasma through an ionization source—soft particle precipitation associated with the polar cusp. In this study, however, we are able to measure the electron temperature as well as number density and drift velocity. These measurements indicate that the electron temperature is not elevated within the density enhancement suggesting that the enhancement is not caused by local soft particle precipitation. Rather, it may simply be F‐region plasma convected from lower latitudes with correspondingly lower solar zenith angles.

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“…Baron and Wand (1983a), however, reported these anomalies in Alaska (65.1 • N) on the basis of the Chatanika incoherent radar observations. A couple of years later, the winter anomaly at Tromsφ (69.6 • N, 19.2 • E) was reported by Farmer et al (1990).…”

Section: Introductionmentioning

confidence: 99%

Climatological features of electron density in the polar ionosphere from long-term observations of EISCAT/ESR radar

Cai

Fan

et al. 2007

Ann. Geophys.

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Abstract. In this paper, climatological features of the polar F2-region electron density (N e ) are investigated by means of statistical analysis using long-term observations from the European Incoherent Scatter UHF radar (called EISCAT in the following) and the EISCAT Svalbard radar (ESR) during periods of quiet to moderate geomagnetic activity. Fieldaligned measurements by the EISCAT and ESR radars operating in CP-1 and CP-2 modes are used in this study, covering the years 1988-1999 for EISCAT and 1999-2003 for ESR. The data are sorted by season (equinox, summer and winter) and solar cycle phase (maximum, minimum, rising and falling). Some novel and interesting results are presented as follows: (1) The well-known winter anomaly is evident during the solar maximum at EISCAT, but it dies out at the latitude of the ESR; (2) The daytime peaks of N e at EISCAT for all seasons during solar maximum lag about 1-2 h behind those at ESR, with altitudes about 10-30 km lower. (3) In addition to the daytime peak, it is revealed that there is another peak just before magnetic midnight at ESR around solar maximum, especially in winter and at equinox. The daytime ionization peak around magnetic noon observed by ESR can be attributed to soft particle precipitation in the cusp region, whereas the pre-midnight N e maximum seems likely to be closely related to substorm events which frequently break out during that time sector, in particular for the winter case. (4) Semiannual variations are found at EISCAT during solar minimum and the falling phase of the solar cycle; at the rising phase, however, the EISCAT observations show no obvious seasonal variations.

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Solar cycle and seasonal variations of the ionosphere observed with the Chatanika incoherent scatter radar

Cited by 17 publications

References 5 publications

Climatologic Characteristics of High-Latitude Ionosphere-Eiscat Observations and Comparison with the Iri Model

Climatologic Characteristics of High-Latitude Ionosphere-Eiscat Observations and Comparison with the Iri Model

F‐region ionospheric structure associated with antisunward flow near the dayside polar cusp

Climatological features of electron density in the polar ionosphere from long-term observations of EISCAT/ESR radar

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