A Year‐Long Comparison of GPS TEC and Global Ionosphere‐Thermosphere Models

Perlongo, N. J.; Ridley, A. J.; Cnossen, Ingrid; Wu, Chen

doi:10.1002/2017ja024411

Cited by 20 publications

(16 citation statements)

References 77 publications

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“…Perlongo et al (2018) showed that this is partly related to a very large O∕N 2 ratio, in particular at low latitudes. First, it appears that the heating mechanisms in GITM might be too strong compared to the cooling mechanisms.…”

Section: Discussionmentioning

confidence: 98%

The Response of the Ionosphere‐Thermosphere System to the 21 August 2017 Solar Eclipse

et al. 2019

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We simulated the effects of the 21 August 2017 total solar eclipse on the ionosphere‐thermosphere system with the Global Ionosphere Thermosphere Model (GITM). The simulations demonstrate that the horizontal neutral wind modifies the eclipse‐induced reduction in total electron content (TEC), spreading it equatorward and westward of the eclipse path. The neutral wind also affects the neutral temperature and mass density responses through advection and the vertical wind modifies them further through adiabatic heating/cooling and compositional changes. The neutral temperature response lags behind totality by about 35 min, indicating an imbalance between heating and cooling processes during the eclipse, while the ion and electron temperature responses have almost no lag, indicating they are in quasi steady state. Simulated ion temperature and vertical drift responses are weaker than observed by the Millstone Hill Incoherent Scatter Radar, while simulated reductions in electron density and temperature are stronger. The model misses the observed posteclipse enhancement in electron density, which could be due to the lack of a plasmasphere in GITM. The simulated TEC response appears too weak compared to Global Positioning System TEC measurements, but this might be because the model does not include electron content above 550‐km altitude. The simulated response in the neutral wind after the eclipse is too weak compared to Fabry Perot interferometer observations in Cariri, Brazil, which suggests that GITM recovers too quickly after the eclipse. This could be related to GITM heating processes being too strong and electron densities being too high at low latitudes.

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Section: Discussionmentioning

confidence: 98%

The Response of the Ionosphere‐Thermosphere System to the 21 August 2017 Solar Eclipse

et al. 2019

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“…In most cases, 11_CTIPE and 6_GITM tend to underestimate percentage changes, while 1_UAM‐P and 11_TIE‐GCM overestimate them. The differences in performance among these four simulations could be caused by inherent differences among the models, for example, different methods to solve for chemistry and advection, and different ways to treat eddy diffusion and vertical transport (Fuller‐Rowell et al, ; Perlongo et al, ; Prokhorov et al, ; Ridley et al, ; Solomon et al, ). In addition, the performance differences could also be caused by a combination of different input data and different models used for lower boundary forcing and high‐latitude electrodynamics, since each simulation was obtained by using its default input data and drivers.…”

Section: Discussionmentioning

confidence: 99%

“…The Ionosphere Plasmasphere Density Working Team performed its first validation study of foF2 and TEC predictions using various ionosphere/thermosphere models. This study is the first quantitative assessment of both parameters based on a set of metrics, unlike a number of validation studies done previously (Anderson et al, ; Araujo‐Pradere et al, ; Burns et al, ; Feltens et al, ; Fuller‐Rowell, Codrescu, et al, ; Orús et al, , ; Perlongo et al, ; Zhu et al, ).…”

Section: Introductionmentioning

confidence: 95%

Validation of Ionospheric Specifications During Geomagnetic Storms: TEC and foF2 During the 2013 March Storm Event

et al. 2018

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To address challenges of assessing space weather modeling capabilities, the Community Coordinated Modeling Center is leading a newly established International Forum for Space Weather Modeling Capabilities Assessment. This paper presents preliminary results of validation of modeled foF2 (F 2 layer critical frequency) and TEC (total electron content) during the first selected 2013 March storm event (17 March 2013). In this study, we used eight ionospheric models ranging from empirical to physics-based, coupled ionosphere-thermosphere and data assimilation models. The quantities we considered are TEC and foF2 changes and percentage changes compared to quiet time background, and the maximum and minimum percentage changes. In addition, we considered normalized percentage changes of TEC. We compared the modeled quantities with ground-based observations of vertical Global Navigation Satellite System TEC (provided by Massachusetts Institute of Technology Haystack Observatory) and foF2 data (provided by Global Ionospheric Radio Observatory) at the 12 locations selected in middle latitudes of the American and European-African longitude sectors. To quantitatively evaluate the models' performance, we calculated skill scores including correlation coefficient, root-mean square error (RMSE), ratio of the modeled to observed maximum percentage changes (yield), and timing error. Our study indicates that average RMSEs of foF2 range from about 1 MHz to 1.5 MHz. The average RMSEs of TEC are between~5 and~10 TECU (1 TEC Unit = 10 16 el/m 2 ). dfoF2[%] RMSEs are between 15% and 25%, which is smaller than RMSE of dTEC[%] ranging from 30% to 60%. The performance of the models varies with the location and metrics considered.To address the needs and challenge of assessment of our current knowledge about space weather effects on IT system and current state of IT modeling capabilities, the Community Coordinated Modeling Center (CCMC) has been supporting community-wide model validation projects, including Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) and Geospace Environment Modeling (GEM)-CEDAR modeling challenges. The CCMC initiated the CEDAR electrodynamics thermosphere ionosphere challenge in 2009 focusing on the evaluation of basic IT system parameters modeled, such as electron and neutral densities, the ionospheric F 2 layer peak electron density (NmF2) and peak height (hmF2), and vertical drift (Shim Key Points: • foF2/TEC and foF2/TEC changes during a storm predicted by eight ionosphere models were compared with GIRO foF2 and GPS TEC measurements • Skill scores (e.g., correlation coefficient, RMSE, yield, and timing error) were calculated • Model performance strongly depends on the quantities considered, the type of metrics used, and the location considered Supporting Information: • Supporting Information S1 Correspondence to: J. S. Shim, jasoon.shim@nasa.gov Citation: Shim, J. S., Tsagouri, I., Goncharenko, L., Rastaetter, L., Kuznetsova, M., Bilitza, D., et al. (2018). Validation of ionospheric specifications du...

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“…We would expect the correction of N 2 and other parameters in the lower thermosphere to bring the model results even closer to the observations. It was shown by Perlongo et al (2018) that GITM has lower summer electron densities than the GPS TEC observations in both the northern and southern midlatitudes. Using GITM w/ WACCM-X at the lower boundary, this will potentially be corrected as the electron density depends on the O/N 2 .…”

Section: Journal Of Geophysical Research: Space Physicsmentioning

confidence: 93%

Impacts of Lower Thermospheric Atomic Oxygen on Thermospheric Dynamics and Composition Using the Global Ionosphere Thermosphere Model

et al. 2020

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The exchange of energy between the lower atmosphere and the ionosphere thermosphere system is not well understood. One of the parameters that is important in the lower thermosphere is atomic oxygen. It has recently been observed that atomic oxygen is higher in summer at ∼95 km. In this study, we investigate the sensitivity of the upper thermosphere to lower thermospheric atomic oxygen using the Global Ionosphere Thermosphere Model (GITM). We use the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) to drive the lower atmospheric boundary of atomic oxygen in GITM between ∼95 and 100 km and compare the results with the current mass spectrometer incoherent scatter (MSIS) driven GITM. MSIS has higher atomic oxygen in the winter hemisphere while WACCM-X has higher atomic oxygen in the summer hemisphere. The reversal of atomic oxygen distribution affects the pressure distribution between 100 and 120 km, such that the hemisphere with larger O number density has stronger equatorward winds, and lower temperature mainly due to adiabatic and radiative cooling. This affects thermospheric scale heights such that the hemisphere with more O has lower N 2 and thus enhanced O/N 2. This behavior is observed in the opposite hemisphere when MSIS is used as the lower boundary for GITM. Overall, O/N 2 for WACCM-X driven GITM matches better with the global ultraviolet imager (GUVI) data. We find that the impact of lower thermospheric atomic oxygen on upper thermosphere is not just through diffusive equilibrium but also through secondary effects on winds and temperature.

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A Year‐Long Comparison of GPS TEC and Global Ionosphere‐Thermosphere Models

Cited by 20 publications

References 77 publications

The Response of the Ionosphere‐Thermosphere System to the 21 August 2017 Solar Eclipse

The Response of the Ionosphere‐Thermosphere System to the 21 August 2017 Solar Eclipse

Validation of Ionospheric Specifications During Geomagnetic Storms: TEC and foF2 During the 2013 March Storm Event

Impacts of Lower Thermospheric Atomic Oxygen on Thermospheric Dynamics and Composition Using the Global Ionosphere Thermosphere Model

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