Proxy for the ionospheric peak plasma density reduced by the solar zenith angle

Abstract

The F 2 layer peak plasma density N m F 2 is reduced by the factor constructed from the relative changes in the Sun's zenith angle χ for a particular local time and the local noon value χ 0 . Proposed transformation yields a proxy for the peak plasma density which coincides with the source observation at noon but apart from the latter is gradually reduced towards the night. Hourly observations at 8 ground based ionosondes for the solar maximum (2000) and minimum (2006) are analyzed for inter-stations and inter-seasonal correlation of the peak plasma density and the proxy values. The proxy values show improved correlation between the data at different locations and improved inter-seasonal correlations for a particular location due to greater homogeneity of results throughout the year contributing to improved evaluation of the ionospheric weather indices.

Magnetosphere-associated storms and the autonomous storms in the ionosphere–plasmasphere environment

“…The differences in the diurnal/seasonal contribution of the solar ionizing radiation on the globe have been reduced with a factor in terms of the solar zenith angle w at a particular time and the local noon value w 0 (Gulyaeva, 2009) referred to geodetic latitude and longitude of the MLAT-MLT grid points of the map. The proxy for TEC(w,w 0 ) coincides with observation at local noon but it is gradually reduced from day to night, providing similarity of the shape of the diurnal profile at all seasons throughout the year everywhere on the globe.…”

Probability density function estimation for characterizing hourly variability of ionospheric total electron content

“…where f (x) = x 2 − a x + b denotes a polynomial with coefficients a = 3.54 and b = 3.875 as given in [Gulyaeva, 2007]. Here, c is the solar zenith angle and c 0 is the smallest value of c that corresponds to high noon.…”

“…Therefore, lognormal can be used as a representative distribution as an initial guess for any station and any hour. [18] Keeping the role of solar radiation in ionization process in mind, a possible normalization in TEC values according to the solar zenith angle of GPS station can be obtained according to the discussion in [Gulyaeva, 2007]. The solar zenith angle normalization of TEC can be computed as…”

Inter-hemispheric imaging of the ionosphere with the upgraded IRI-Plas model during the space weather storms

“…The variations in f o F 2 at a 'parent' station are used for the reconstruction of a measurement missed at another location. The transform is applied to the proxy for the F 2 -layer critical frequency reduced by the solar zenith angle which improves the correlation between the data at different locations (Gulyaeva, 2009). This procedure assumes the availability of the daily-hourly values of critical frequency measured at a particular parent station and the median for the preceding 27 days at both stations.…”