Comparison between IRI predictions and digisonde measurements at Tucumán

Ríos, V. H.; Medina, Catalina; Álvarez, Paula Fernández

doi:10.1016/j.jastp.2006.10.004

Cited by 27 publications

(20 citation statements)

References 13 publications

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“…There are at least three problems (apart from the O + -O collision frequency one discussed later) related to this method: (1) [34] Dudeney [1983] suggests that his method should provide values of h m F 2 with an RMS error of about 5% (15 km if h m F 2 ≈ 300 km) at temperate magnetic latitudes. A comparison of IRI-2001 h m F 2 predictions with Digisonde measurements at Tucuman during quiet days gave the difference up to 20-30 km [Rios et al, 2007]. Similar comparison at Brazilian low-latitude stations gave the same difference 25-30 km in a comparison with IRI-2001 h m F 2 predictions.…”

Section: Seasonal Variationssupporting

confidence: 51%

On the mechanism of seasonal and solar cycleN_mF₂variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations

Mikhailov

Perrone

2011

J. Geophys. Res.

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[1] Seasonal (winter/summer) and solar cycle N m F 2 variations as well as summer saturation effect in N m F 2 have been analyzed using Millstone Hill incoherent scatter radar (ISR) daytime observations. A self-consistent approach to the Ne(h) modeling has been applied to extract from ISR observations a consistent set of main aeronomic parameters and to estimate their quantitative contribution to the observed N m F 2 variations. The retrieved aeronomic parameters are independent of uncertainties in thermosphere and solar EUV empirical models, and this is a distinguishing feature of the present consideration. Different temperatures in winter and in summer in the course of solar cycle overlapped on the O + + N 2 reaction rate coefficient temperature dependence result in different N m F 2 dependences on solar activity: a steep practically linear increase with a tendency to turn up in January (contrary to international reference ionosphere prediction) and a slow increase with a tendency to saturate at high solar activity in July despite increasing solar EUV irradiation. In winter the EUV flux and thermospheric parameters provide approximately equal contributions to the N m F 2 increase, while in summer the contribution of thermospheric parameters is small. Both in winter and in summer the variations of atomic oxygen [O] are small at the F 2 layer peak, and its contribution is small compared to linear loss coefficient, b. It is shown that the summer saturation effect in N m F 2 under high solar activity is not just reduced to O/N 2 or EUV flux solar cycle variations but is determined by b via the g 1 temperature dependence. A new mechanism (qualitative) to explain the December anomaly in N m F 2 is proposed. It is based on the idea that the areas of atomic oxygen production and its loss are spatially separated and that time is required to transfer [O] from one area to the other where [O] associates in a three-body collision. Therefore, under a 7% increase in the O 2 dissociation rate due to the Sun-Earth distance decrease in December-January compared to June-July, an accumulation of atomic oxygen should take place in the thermosphere in the vicinity of the December solstice resulting in a 21% N m F 2 increase, which is close to the observed global December effect.Citation: Mikhailov, A. V., and L. Perrone (2011), On the mechanism of seasonal and solar cycle N m F 2 variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations,

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Section: Seasonal Variationssupporting

confidence: 51%

On the mechanism of seasonal and solar cycleN_mF₂variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations

Mikhailov

Perrone

2011

J. Geophys. Res.

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“…This could make the electron density profile skewer during daytime hours and flat during nighttime hours leading to the underestimation and overestimation of TEC during day and nighttime hours, respectively. Rios et al [2007] have compared the IRI-modeled slab-thickness with the experimental data and reported that the model-derived slab-thickness is lower during daytime hours and higher during nighttime hours compared to those of the experimental slabthickness values. The present study also revealed several differences between the modeled and experimental TEC and also there are significant differences between the IRI-2012 and NeQuick2 model-derived TEC values.…”

Section: Discussionmentioning

confidence: 99%

On the performance of the IRI‐2012 and NeQuick2 models during the increasing phase of the unusual 24th solar cycle in the Brazilian equatorial and low‐latitude sectors

Venkatesh

Fagundes

Seemala³

et al. 2014

JGR Space Physics

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It is known that the equatorial and low-latitude ionosphere is characterized with typical dynamical phenomena namely, the equatorial ionization anomaly (EIA). Accurate modeling of the characteristic variations of the EIA is more important to arrive at the correct estimation of range delays required for the communication and navigation applications. The total electron content (TEC) data from a chain of Global Positioning System (GPS) receivers at seven identified locations from equator to the anomaly crest and beyond along 315°E geographic longitude in the Brazilian sector are considered. The performances of the latest available IRI-2012 and NeQuick2 models have been investigated during 2010-2013 in the increasing phase of the 24th solar cycle. A comparative study on the morphological variations of the GPS measured and modeled TEC revealed that the performances of the models are improved during low solar activity periods compared to that during the increased solar activity years. The strength and the locations of the EIA crest are nearly well represented by both the models during the low solar activity while the models underestimate the peak TEC at the EIA during the increased solar activity conditions. The deviations between the GPS-measured and model-derived TEC are more during equinoctial and summer months at and around the anomaly crest locations. Significant differences have also been observed in between the TEC values derived from both the models. The causes for the discrepancies in the modeled TEC values are discussed based on the model-derived and ionosonde-measured vertical electron density profiles variations.

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“…They compared the GPS ionosphere reconstruction results with IRI-2001 and found that these were overestimated in daytime in winter but almost always underestimated in other seasons. Rios et al (2007) studied several parameters, critical frequency foF2, TEC, F2 layer peak height hmF2, and slab thickness (s) measured with a Digisonde 256 and compared their results with IRI-2001 predictions for Tucuman during quiet days in 2003. They observed a strong dependence of experimental and predicted diurnal curves on local time and season.…”

Section: Introductionmentioning

confidence: 99%

A morphological study of GPS-TEC data at Agra and their comparison with the IRI model

Chauhan¹,

Singh²

2010

Advances in Space Research

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Comparison between IRI predictions and digisonde measurements at Tucumán

Cited by 27 publications

References 13 publications

On the mechanism of seasonal and solar cycleN_mF₂variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations

On the mechanism of seasonal and solar cycleN_mF₂variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations

On the performance of the IRI‐2012 and NeQuick2 models during the increasing phase of the unusual 24th solar cycle in the Brazilian equatorial and low‐latitude sectors

A morphological study of GPS-TEC data at Agra and their comparison with the IRI model

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Comparison between IRI predictions and digisonde measurements at Tucumán

Cited by 27 publications

References 13 publications

On the mechanism of seasonal and solar cycleNmF2variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations

On the mechanism of seasonal and solar cycleNmF2variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations

On the performance of the IRI‐2012 and NeQuick2 models during the increasing phase of the unusual 24th solar cycle in the Brazilian equatorial and low‐latitude sectors

A morphological study of GPS-TEC data at Agra and their comparison with the IRI model

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On the mechanism of seasonal and solar cycleN_mF₂variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations

On the mechanism of seasonal and solar cycleN_mF₂variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations