Measurement of <i>E</i>‐Layer Effective Recombination Coefficient During Solar Flares

Wagner, L. S.; Thome, G. D.

doi:10.1029/rs007i004p00469

Cited by 8 publications

(4 citation statements)

References 15 publications

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“…The importance of f increases as we establish its relationship to the several parameters mentioned. The two data points at 94 and 100 km were obtained byWagner and Thome [1972] using solar flare X ray intensities measured by satellite in conjunction with electron density measurements obtained with the Arecibo incoherent scatter radar. The spread in the values of f at a given altitude reflects real dependences on such parameters as production rate and solar zenith angle, as we shall see later, in addition to inaccuracies introduced by spatial and temporal variations in the auroral fluxes and variations in the radar parameters.…”

supporting

confidence: 88%

Simultaneous satellite and radar studies of theDregion ionosphere during the intense solar particle events of August 1972

Reagan¹,

Watt²

1976

J. Geophys. Res.

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During the intense solar particle events of August 3–11, 1972, 28 cases of simultaneous data were obtained between the polar‐orbiting satellite 1971‐089A and the incoherent scatter radar at Chatanika, Alaska. Effective electron loss rates (ψ) in the D region ionosphere have been derived as a function of altitude, solar zenith angle (χ), and the magnitude of the production rate (Q). Production rate profiles extending from 3 × 10² to 3 × 104 ion pairs/cm³ s were calculated for the 40‐ to 90‐km region. Electron density profiles extending from 5 × 10³ to 105 el/cm³ were measured, useful data being obtained down to altitudes as low as 50 km. Values of ψ were obtained for daytime and sunrise/sunset conditions over a range of solar zenith angles from 50.4° to 98.6°. A strong diurnal dependence in ψ was observed only at altitudes below 80 km. Twilight values of ψ at the lower altitudes were over an order of magnitude larger than the daytime values. Between 70‐ and 90‐km altitude the present polar summer daytime values of ψ are significantly larger than those obtained in the winter daytime event of November 2, 1969. Near 80‐km altitude the present results are consistent with the dominant ions being the hydrated ions H3O+ (amu = 19) and H3O+·H2O (amu = 37). A strong seasonal dependence in the effective loss rates has therefore been established. A pronounced asymmetry in ψ and Ne between the sunrise and sunset twilights was measured at altitudes <80 km, the electron density at sunset being larger than at sunrise at the same solar zenith angle. The altitude behavior of ψ and the temporal leads and lags measured in the transitions between twilight and day were found to be consistent with the interaction of the solar visible and ultraviolet wavelengths with the ozone layers above the earth, leading to the sunrise increase and sunset decay of O and O2(¹Δ). The dependence of ψ on the magnitude of the production rate during the day was found to be weak, a slight positive dependence being measured at altitudes <63 km.

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supporting

confidence: 88%

Simultaneous satellite and radar studies of theDregion ionosphere during the intense solar particle events of August 1972

Reagan¹,

Watt²

1976

J. Geophys. Res.

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“…Whitten et al (1965); Parthasarathy and Rai (1965); Gledhill (1986) have developed theoretical methods for empirical expressions for α ef f (it includes α i , α D , λ and other dust capture coefficients of aerosol theory). Wagner and Thome (1972) proposed a different method namely 'Thomson Scatter Experimental Technique' to simulate electron density and α ef f during solar flares relative to pre-flare condition at E-region. According to Appleton (1953), the N e and α ef f are directly related to time delay △t.…”

Section: Introductionmentioning

confidence: 99%

Effective recombination coefficient and solar zenith angle effects on low-latitude D-region ionosphere evaluated from VLF signal amplitude and its time delay during X-ray solar flares

Basak

Chakrabarti

2013

Astrophys Space Sci

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delay is anti-correlated with the flare peak energy flux φ max independent of these time slots, the goodness of fit, as measured by reduced-χ 2 , actually worsens as the day progresses. The variation of the Z dependence of reduced-χ 2 seems to follow the variation of standard deviation of Z along the T x -R x propagation path. In other words, for the flares having almost constant Z over the path a tighter anti-correlation between △t and φ max was observed.

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“…The value of the effective recombination coefficient is influenced by the ionic composition, the state of excitation, the temperature of the ionosphere, and the electron density. As indicated by several authors, α is usually 1-3 10 -7 cm 3 /seg for the E layer (Wagner and Thome, 1972;Bates, 1988). Thus, according to the observed delays (almost 1,030 s), assuming that a noticeable effect (80% perturbation) becomes evident at 1.6 τ. Supposing α 1.5 10 -7 cm 3 /seg, it yields an N value of 1.1 10 4 /cm 3 , which is not an unexpected value.…”

Section: Geomagnetic Field Variationmentioning

confidence: 57%

Analysis of Ionospheric and Geomagnetic Response to the 2020 Patagonian Solar Eclipse

Meza

Eylenstein

Natali

et al. 2021

Front. Astron. Space Sci.

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Total solar eclipses are unique opportunities to study how the ionospheric and external geomagnetic field responds to fast changes in the ionizing flux as the moon’s shadow travels through its path over the ionosphere at an average speed of 3,000 km/h. In this contribution, we describe our observing campaign in which we set up GNSS and geomagnetic stations at the city of Valcheta, Río Negro, Argentina (which was located right under the path of totality). We also describe the results obtained from the analysis of the combination of on-site data together with publicly available observations from geodetic and geomagnetic observatories. The large span in latitude of our data allowed us to analyze the different magnitudes of the drop in vertical total electron content (ΔVTEC) with varying occultation percentages. We found an expected reduction in this drop as we move away from totality path but we also detected a new increment in ΔVTEC as we got closer to Earth’s Magnetic Equator. We also compared our observations of the geomagnetic field variations with predictions that were based on the Ashour-Chapman model and we find an overall good agreement, although a ≈20 min delay with the eclipse maximum is evident beyond observing uncertainties. This suggests the presence of processes that delay the response of the lower ionosphere to the loss of the photoionization flux.

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Measurement of E‐Layer Effective Recombination Coefficient During Solar Flares

Cited by 8 publications

References 15 publications

Simultaneous satellite and radar studies of theDregion ionosphere during the intense solar particle events of August 1972

Simultaneous satellite and radar studies of theDregion ionosphere during the intense solar particle events of August 1972

Effective recombination coefficient and solar zenith angle effects on low-latitude D-region ionosphere evaluated from VLF signal amplitude and its time delay during X-ray solar flares

Analysis of Ionospheric and Geomagnetic Response to the 2020 Patagonian Solar Eclipse

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