FORMOSAT-3/COSMIC<i>E</i>region observations and daytime foE at middle latitudes

Perrone, Loredana; Михайлов, А. А.; Korsunova, L. P.

doi:10.1029/2010ja016411

Cited by 8 publications

(8 citation statements)

References 16 publications

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“…A detailed examination of the noontime data presented in Figures 1 and 2 of Perrone et al . [] shows that the range of the relative differences in the N m E values between COSMIC retrieval and ionosonde measurement is about 30–60% that is consistent with that of the GPS RO retrieval errors of the N m E values simulated by IRI model at midlatitudes as shown in Figure . Moreover, COSMIC‐observed E s layers deduced from amplitude and phase fluctuations of GPS signal at 1 Hz and 50 Hz sampling rate both show that there is no observational evidence of the E s layer permanently existing at midlatitude around 30°–40° [ Arras et al ., ; Chu et al ., ].…”

Section: Discussionsupporting

confidence: 76%

“…In order to explain the formation of abnormal enhancement of COSMIC‐measured E region electron density at midlatitude, Perrone et al . [] analyzed the E s data measured by the ionosondes at Rome and Gibilmanna for several months of 2006 and 2007 and conjectured that the E region electron density enhancement is caused by the permanent existence of large electron density associated with daytime E s layer, rather than the GPS RO retrieval error. A detailed examination of the noontime data presented in Figures 1 and 2 of Perrone et al .…”

Section: Discussionmentioning

confidence: 99%

“…In order to explain the formation of abnormal enhancement of COSMIC-measured E region electron density at midlatitude, Perrone et al [2011] analyzed the E s data measured by the ionosondes at Rome and Gibilmanna for several months of 2006 and 2007 and conjectured that the E region electron density enhancement is caused by the permanent existence of large electron density associated with daytime E s layer, rather than the GPS RO retrieval error. A detailed examination of the noontime data presented in Figures 1 and 2 shows that the range of the relative differences in the N m E values between COSMIC retrieval and ionosonde measurement is about 30-60% that is consistent with that of the GPS RO retrieval errors of the N m E values simulated by IRI model at midlatitudes as shown in Figure 2.…”

Section: Discussionmentioning

confidence: 99%

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Improvement of GPS radio occultation retrieval error of E region electron density: COSMIC measurement and IRI model simulation

Chu

2015

JGR Space Physics

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In this article, we use the International Reference Ionosphere (IRI) model to simulate temporal and spatial distributions of global E region electron densities retrieved by the FORMOSAT-3/COSMIC satellites by means of GPS radio occultation (RO) technique. Despite regional discrepancies in the magnitudes of the E region electron density, the IRI model simulations can, on the whole, describe the COSMIC measurements in quality and quantity. On the basis of global ionosonde network and the IRI model, the retrieval errors of the global COSMIC-measured E region peak electron density (N m E) from July 2006 to July 2011 are examined and simulated. The COSMIC measurement and the IRI model simulation both reveal that the magnitudes of the percentage error (PE) and root mean-square-error (RMSE) of the relative RO retrieval errors of the N m E values are dependent on local time (LT) and geomagnetic latitude, with minimum in the early morning and at high latitudes and maximum in the afternoon and at middle latitudes. In addition, the seasonal variation of PE and RMSE values seems to be latitude dependent. After removing the IRI model-simulated GPS RO retrieval errors from the original COSMIC measurements, the average values of the annual and monthly mean percentage errors of the RO retrieval errors of the COSMIC-measured E region electron density are, respectively, substantially reduced by a factor of about 2.95 and 3.35, and the corresponding root-mean-square errors show averaged decreases of 15.6% and 15.4%, respectively. It is found that, with this process, the largest reduction in the PE and RMSE of the COSMIC-measured N m E occurs at the equatorial anomaly latitudes 10°N-30°N in the afternoon from 14 to 18 LT, with a factor of 25 and 2, respectively. Statistics show that the residual errors that remained in the corrected COSMIC-measured N m E vary in a range of À20% to 38%, which are comparable to or larger than the percentage errors of the IRI-predicted N m E fluctuating in a range of À6.5% to 20%.

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Section: Discussionsupporting

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Improvement of GPS radio occultation retrieval error of E region electron density: COSMIC measurement and IRI model simulation

Chu

2015

JGR Space Physics

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“…Possible explanation may be related to sporadic E which is very probable during daytime summer conditions at middle latitudes. The analysis of FORMOSAT-3/COSMIC RO profiles in Rome whose latitude is close to the latitude of Millstone Hill has shown a strong influence of sporadic E on the Ne(h) distribution in the bottom side (Perrone et al 2011). Our analysis of Millstone Hill ISR profiles for the summer dates listed in Figure 5 has shown the existence of strong underlying ionization below 150 km which should influence RO profiles.…”

Section: Assessment Of the Resultsmentioning

confidence: 99%

On the possible use of radio occultation middle latitude electron density profiles to retrieve thermospheric parameters

Михайлов

Belehaki

Perrone

et al. 2014

J. Space Weather Space Clim.

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This paper investigates possible use of middle latitude daytime COSMIC and CHAMP ionospheric radio occultation (IRO) electron density profiles (EDPs) to retrieve thermospheric parameters, based on the Mikhailov et al. (2012) method. The aim of this investigation is to assess the applicability of this type of observations for the routine implementation of the method. According to the results extracted from the analysis presented here, about half of COSMIC IRO EDP observed under solar minimum (2007)(2008) conditions gave neutral gas density with an inaccuracy close to the declared absolute inaccuracy ±(10-15)% of CHAMP observations, with the results being better than the empirical models JB-2008 and MSISE-00 provide. For the other half of IRO EDP, either the solution provided by the method had to be rejected due to insufficient accuracy or no solution could be obtained. For these cases, the parameters foF2 and hmF2 extracted from the corresponding IRO profiles have been found to be inconsistent with the classic mid-latitude daytime F2-layer formalism that the method relies on, and they are incompatible with the general trend provided by the IRI model. For solar maximum conditions (2002) the method was tested with IRO EDP from CHAMP and it is indicated that its performance is quite stable in the sense that a solution could be obtained for all the cases analyzed here. However available CHAMP EDP are confined by~400 km in altitude and this might be the reason for the 20% bias of the retrieved densities toward larger values in respect to the observed densities. IRO observations up to 600 km under solar maximum are required to confirm the exact performance of the method.

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“…The height uncertainties in this case, however, are not expected to be causing significant errors in the modeled electron densities, because the NeE (h) profile at these upper heights varies insignificantly within a few kilometers in altitude. With regard to the accuracy of the IRI model electron densities, various validation studies show IRI to be capable in producing fairly realistic E region electron density profiles at midlatitude from about 100 to 140 km, where sporadic E layers are mostly located (e.g., see Mostafa et al, ; Perrone et al, ; Yang et al, 2017, and more references therein). Note that it is outside the scope of this paper to deal in detail with the errors the proposed algorithm introduces in NmμEs and foμEs .…”

Section: A Simple Algorithm To Derive An Improved Parameter For Es Qumentioning

confidence: 99%

An Improved Ionosonde‐Based Parameter to Assess Sporadic E Layer Intensities: A Simple Idea and an Algorithm

Haldoupis

2019

JGR Space Physics

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In the long era of sporadic E layer (Es) ionosonde research, the ordinary wave critical frequency foEs is used as a measure of Es layer occurrence and intensity. This practice, however, undermines that sporadic E layers are in fact metal ion layers, whereas foEs relates inherently to the sum of both the layer metal and the regular E region plasma densities. This means that foEs acts as an overestimate of Es intensity, a fact that somehow has been overlooked and escaped attention. To deal with this deficiency, an algorithm is introduced which combines the ionosonde-measured foEs and virtual height h'Es parameters with International Reference Ionosphere model predictions of E region electron densities, to arrive at a new critical frequency which depends on sporadic E metal plasma density only; therefore, it represents an unbiased estimate of Es layer intensity. The extensive use of foEs in numerous sporadic E studies must have introduced errors in various results in relation with the Es variability in the time, frequency, and space domains. It is therefore important that this new parameter, notated as foμEs, is now adopted and used instead of foEs in the evaluation of sporadic E. The same methodology applies also for the sporadic E blanketing critical frequency fbEs, which at times is taken as an alternative estimate of Es intensity; similarly, a new parameter, notated as fbμEs, should be used instead of fbEs. Key Points: • The ionosonde foEs critical frequency is used as a measure of sporadic E layer intensity; this undermines that Es are metal ion layers • foEs overestimates sporadic E intensity because it relates to the sum of the layer metal atomic ion and E region molecular ion densities • A method is developed combining ionosonde Es parameters and IRI model electron densities to derive an unbiased estimate of Es intensity

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FORMOSAT-3/COSMICEregion observations and daytime foE at middle latitudes

Cited by 8 publications

References 16 publications

Improvement of GPS radio occultation retrieval error of E region electron density: COSMIC measurement and IRI model simulation

Improvement of GPS radio occultation retrieval error of E region electron density: COSMIC measurement and IRI model simulation

On the possible use of radio occultation middle latitude electron density profiles to retrieve thermospheric parameters

An Improved Ionosonde‐Based Parameter to Assess Sporadic E Layer Intensities: A Simple Idea and an Algorithm

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