A comparison of electron density profiles over Ahmedabad in years of low and high solar activity

Abstract. The theoretical PGI (Polar Geophysical Institute) model for the quiet lower ionosphere has been applied for computing the ionization rate and electron density profiles in the summer and winter D-region at solar zenith angles less than 80° and larger than 99° under steady state conditions. In order to minimize possible errors in estimation of ionization rates provided by solar electromagnetic radiation and to obtain the most exact values of electron density, each wavelength range of the solar spectrum has been divided into several intervals and the relations between the solar radiation intensity at these wavelengths and the solar activity index F10.7 have been incorporated into the model. Influence of minor neutral species (NO, H2O, O, O3) concentrations on the electron number density at different altitudes of the sunlit quiet D-region has been examined. The results demonstrate that at altitudes above 70 km, the modeled electron density is most sensitive to variations of nitric oxide concentration. Changes of water vapor concentration in the whole altitude range of the mesosphere influence the electron density only in the narrow height interval 73–85 km. The effect of the change of atomic oxygen and ozone concentration is the least significant and takes place only below 70 km. Model responses to changes of the solar zenith angle, solar activity (low–high) and season (summer–winter) have been considered. Modeled electron density profiles have been evaluated by comparison with experimental profiles available from the rocket measurements for the same conditions. It is demonstrated that the theoretical model for the quiet lower ionosphere is quite effective in describing variations in ionization rate, electron number density and effective recombination coefficient as functions of solar zenith angle, solar activity and season. The model may be used for solving inverse tasks, in particular, for estimations of nitric oxide concentration in the mesosphere.

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Comparison of ionospheric radio occultation CHAMP data with IRI 2001

Advances in Radio Science ◽

10.5194/ars-2-275-2004 ◽

2005 ◽

Vol 2 ◽

pp. 275-279 ◽

Cited By ~ 5

Author(s):

N. Jakowski ◽

K. Tsybulya

Keyword(s):

Electron Density ◽

Radio Occultation ◽

Satellite Orbit ◽

High Solar Activity ◽

Satellite Mission ◽

Density Profiles ◽

Champ Satellite ◽

Ionospheric Models ◽

Routine Basis ◽

Electron Density Profiles

Abstract. GPS radio occultation measurements on board low Earth orbiting satellites can provide vertical electron density profiles of the ionosphere from satellite orbit heights down to the bottomside. Ionospheric radio occultation (IRO) measurements carried out onboard the German CHAMP satellite mission since 11 April 2001 were used to derive vertical electron density profiles (EDP’s) on a routine basis. About 150 vertical electron density profiles may be retrieved per day thus providing a huge data basis for testing and developing ionospheric models. Although the validation of the EDP retrievals is not yet completed, the paper addresses a systematic comparison of about 78 000 electron density profiles derived from CHAMP IRO data with the International Reference Ionosphere (IRI 2001). The results are discussed for quite different geophysical conditions, e.g. as a function of latitude, local time and geomagnetic activity. The comparison of IRO data with corresponding IRI data indicates that IRI generally overestimates the upper part of the ionosphere whereas it underestimates the lower part of the ionosphere under high solar activity conditions. In a first order correction this systematic deviation could be compensated by introducing a height dependence correction factor in IRI profiling.

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Comparison of electron density profiles extracted from DIAS maps and ionosonde measurements at Nicosia during low solar activity

2011 XXXth URSI General Assembly and Scientific Symposium ◽

10.1109/ursigass.2011.6050998 ◽

2011 ◽

Author(s):

H. Haralambous

Keyword(s):

Solar Activity ◽

Electron Density ◽

Density Profiles ◽

Electron Density Profiles

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The IRI topside parameters

Advances in Radio Science ◽

10.5194/ars-2-249-2004 ◽

2005 ◽

Vol 2 ◽

pp. 249-251 ◽

Cited By ~ 5

Author(s):

P. Coïsson ◽

S. M. Radicella

Keyword(s):

Electron Density ◽

Wide Spectrum ◽

Critical Conditions ◽

High Solar Activity ◽

Constitutive Parameter ◽

Iri Model ◽

Density Profiles ◽

Electron Density Profiles ◽

Very High

Abstract. The IRI electron density topside has been constructed on the basis of the data available about thirty years ago. Recently a large amount of data from old topside sounders have been processed to get electron density profiles. These profiles allow to test IRI model under a wide spectrum of different conditions and to understand the behavior of the modeled topside. A set of 12 000 topside profiles have been chosen from the ISIS2 database, selecting those with the better quality of the inverted profile. An analysis of each IRI topside constitutive parameter has been done for all the experimental cases allowing to find some critical conditions under which the IRI topside could become completely unrealistic. In particular for very high solar activity at high latitudes it has been found that some IRI parameters could reach values that change drastically the shape of IRI topside. A proposal to control their range of variability is formulated in order to avoid the occurrence of such cases.

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