A New Empirical Model of NmF2 Based on CHAMP, GRACE, and COSMIC Radio Occultation
Abstract
:1. Introduction
2. Data
3. Method
4. Model Performance
4.1. Modeling Results
4.2. Independent Test with Occultation Data
4.3. Independent test with Ionosonde Data
4.4. Ionospheric Features Simulation
5. Discussion
6. Conclusions
- Using NPPDM to reproduce the input data, the mean relative deviation between the input data and the new model is 2.19%. NPPDM shows larger RMSE in the EIA region than in other regions.
- The predictions of NPPDM were compared with independent IRO measurements, IRI2016 predictions, and NPDM predictions. The correlation coefficients between model predictions and actual measurements show that the NPPDM performs better than IRI2016 and NPDM under low solar activity, while it undergoes performance degradation under high solar activity as a result of the poor database coverage.
- Ionosonde data from twelve stations were selected to validate the accuracy of NPPDM. The analog deviations between ionosonde observations and model predictions indicate that the precision of NPPDM is better than that of NPDM and comparable to that of IRI2016.
- The variations and distributions of NmF2 simulated by NPPDM agree well with previous research. NPPDM can capture some ionospheric features including the EIA, the longitudinal wavenumber-4 structure, and the midlatitude trough.
Author Contributions
Acknowledgments
Conflicts of Interest
References
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Space Mission | Number of Data Used | Time Range |
---|---|---|
CHAMP | 1.7 × 105 | 2001.06–2008.09 |
GRACE | 1.1 × 105 | 2007.02–2013.09 |
COSMIC | 3.8 × 106 | 2006.04–2018.04 |
Station | Latitude/°N | Longitude/°E | Low solar activity | High solar activity | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Mar. | Jun. | Sep. | Dec. | Mar. | Jun. | Sep. | Dec. | |||
Gakona | 62 | −145 | √ | √ | √ | √ | √ | |||
Juliusruh | 55 | 13 | √ | √ | √ | |||||
Boulder | 40 | −105 | √ | √ | √ | √ | √ | √ | √ | √ |
Eglin AFB | 30 | −87 | √ | √ | √ | √ | ||||
Puerto Rico | 19 | −67 | √ | √ | √ | √ | ||||
Jicamarca | −12 | −77 | √ | |||||||
Townsille | −20 | 147 | √ | √ | ||||||
Louisvale | −29 | 21 | √ | √ | √ | √ | √ | |||
Camden | −34 | 151 | √ | √ | √ | √ | ||||
Canberra | −35 | 149 | √ | √ | √ | √ | ||||
Port Stanley | −52 | −58 | √ | √ | √ | |||||
Macquarie Is | −55 | 159 | √ | √ | √ | √ | √ |
Station Region | Model | Northern Hemisphere | Southern Hemisphere | ||||||
---|---|---|---|---|---|---|---|---|---|
Mar. | Jun. | Sep. | Dec. | Mar. | Jun. | Sep. | Dec. | ||
Low latitude (0°–30°) | NPPDM | √ | √ | √ | √ | ||||
IRI2016 | √ | √ | √ | ||||||
NPDM | √ | ||||||||
Middle latitude (30°–50°) | NPPDM | √ | √ | √ | √ | √ | |||
IRI2016 | √ | √ | √ | √ | |||||
NPDM | |||||||||
Middle-high latitude (>50°) | NPPDM | √ | √ | √ | √ | ||||
IRI2016 | √ | √ | √ | √ | √ | √ | |||
NPDM |
Station Region | Model | Northern Hemisphere | Southern Hemisphere | ||||||
---|---|---|---|---|---|---|---|---|---|
Mar. | Jun. | Sep. | Dec. | Mar. | Jun. | Sep. | Dec. | ||
Low latitude (0°–30°) | NPPDM | √ | √ | √ | √ | ||||
IRI2016 | √ | √ | √ | √ | |||||
NPDM | |||||||||
Middle latitude (30°–50°) | NPPDM | √ | √ | √ | √ | √ | |||
IRI2016 | √ | √ | √ | ||||||
NPDM | |||||||||
Middle-high latitude (>50°) | NPPDM | √ | √ | ||||||
IRI2016 | √ | √ | √ | √ | √ | ||||
NPDM | √ |
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Liu, Z.; Fang, H.; Hoque, M.M.; Weng, L.; Yang, S.; Gao, Z. A New Empirical Model of NmF2 Based on CHAMP, GRACE, and COSMIC Radio Occultation. Remote Sens. 2019, 11, 1386. https://doi.org/10.3390/rs11111386
Liu Z, Fang H, Hoque MM, Weng L, Yang S, Gao Z. A New Empirical Model of NmF2 Based on CHAMP, GRACE, and COSMIC Radio Occultation. Remote Sensing. 2019; 11(11):1386. https://doi.org/10.3390/rs11111386
Chicago/Turabian StyleLiu, Zhendi, Hanxian Fang, M. M. Hoque, Libin Weng, Shenggao Yang, and Ze Gao. 2019. "A New Empirical Model of NmF2 Based on CHAMP, GRACE, and COSMIC Radio Occultation" Remote Sensing 11, no. 11: 1386. https://doi.org/10.3390/rs11111386