scholarly journals Discrepancy between the nighttime molecular ion composition given by the International Reference Ionosphere model and airglow measurements at low latitudes

2006 ◽  
Vol 111 (A3) ◽  
Author(s):  
Michael J. Nicolls ◽  
Michael N. Vlasov ◽  
Michael C. Kelley ◽  
Gordon G. Shepherd
Keyword(s):  
International Reference Ionosphere ◽  
Ion Composition ◽  
International Reference ◽  
Molecular Ion ◽  
Ionosphere Model ◽  
Low Latitudes

scholarly journals Comparative Preliminary Ionospheric Forecasting In Romania With Data From The European Ionosonde Service Versus Data Extracted From The International Reference Ionosphere Model

2015 ◽  
Vol 21 (3) ◽  
pp. 706-711
Author(s):  
Simona Miclaus ◽  
Paul Bechet ◽  
Mircea Stanic ◽  
Cora Iftode
Keyword(s):  
Time Of Day ◽  
International Reference Ionosphere ◽  
Quality Data ◽  
Radio Link ◽  
Ionospheric Layer ◽  
International Reference ◽  
Ionosphere Model ◽  
Data Links ◽  
Critical Frequency Fof2 ◽  
Model Versus

Abstract Radiocommunications in the HF band depend on the ionospheric parameters of radiowaves reflexion, though the quality of a radio link depends on: the time of day; season; solar cycle; geographical position. Taking into account the ionosphere characteristics over Romania, a forecasting is made over four cities in our country in order to provide the values of the critical frequency foF2 of the F2 ionospheric layer over a 24 hours cycle. A comparative analysis of this parameter is applied by using the International Reference Ionosphere model and interpolated experimental data collected from the European Ionosonde Service. Results show that the f0F2 values are slightly underestimated in all four locations in the model versus measurements, sustaining the necessity of own measurements in order to prepare quality data links in Romania if HF band is to be used for emergency data communications.

scholarly journals Improvements to Predictions of the Ionospheric Annual Anomaly by the International Reference Ionosphere Model

2018 ◽  
Author(s):  
Steven Brown ◽  
Dieter Bilitza ◽  
Erdal Yiğit
Keyword(s):  
Northern Hemisphere ◽  
International Reference Ionosphere ◽  
Model Data ◽  
Iri Model ◽  
International Reference ◽  
Data Comparison ◽  
Ionosphere Model ◽  
Model Predictions ◽  
One Year ◽  
Underlying Processes

Abstract. The annual anomaly is the ionospheric phenomena in which the globally-averaged electron density is greater in January than it is in July. This anomaly causes the ionospheric solsticial variation – a variation with a periodicity of one year that is in-phase with the January solstice – to be more pronounced over the Northern Hemisphere than the Southern Hemisphere. Predictions of the magnitude of annual anomaly using the International Reference Ionosphere (IRI) model have been shown to be unreliable so far. The objective of our study is to investigate model prediction of the magnitude of the annual ionospheric anomaly using new ionospheric indices as inputs in the IRI model. These new indices improve predictions ionospheric variations that differ over the two hemispheres. We present a retrospective analysis of the IRI predictions of the ionospheric daytime annual anomaly and solsticial variation using a model-data comparison with observations from over 40 ionosondes for high, moderate, and low solar cycle conditions. Our results show that there is an overall 33 % underestimation of the magnitude of the annual anomaly when the by the IRI. When the new ionospheric indices as used in the IRI, model predictions underestimate the magnitude of the annual anomaly by 6 %. This indicates an improvement of the model predictions when using the new indices. We show that the underestimation of the annual anomaly by IRI is related to a similar underestimation of the magnitude of the ionospheric solsticial variation over the Northern Hemisphere. Based on our results, we infer that the underlying processes of the annual anomaly must vary across each hemisphere.

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