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Measurements and Models of the Ionosphere: Science Requirements for Space Weather

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Measurements and Models of the Ionosphere: Science Requirements for Space Weather

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    1. 1 Measurements and Models of the Ionosphere: Science Requirements for Space Weather

    2. 2 Outline

    3. 3 “One Man Gathers What Another Man Spills”

    4. 4 Space Weather Effects on the Ionosphere

    5. 5 CORISS Scintillated Profile Examples These are sample occultation profiles on 1-second SNR data from the CORISS (C/NOFS Occultation Receiver for Ionospheric Sensing & Specification) on the equatorial C/NOFS (Communications/Navigation Outage Forecasting Satellite) spacecraft. The S4 scintillation index (x1000) is shown by the dotted red line in each figure. These data were collected under solar minimum conditions (summer 2008), where scintillation is weak. Substantially stronger scintillation was observed during near-solar maximum conditions observed by the earlier Ionospheric Occultation Experiment (IOX – 2001-2004). Scintillation can cause outages in HF through L-band communications systems.These are sample occultation profiles on 1-second SNR data from the CORISS (C/NOFS Occultation Receiver for Ionospheric Sensing & Specification) on the equatorial C/NOFS (Communications/Navigation Outage Forecasting Satellite) spacecraft. The S4 scintillation index (x1000) is shown by the dotted red line in each figure. These data were collected under solar minimum conditions (summer 2008), where scintillation is weak. Substantially stronger scintillation was observed during near-solar maximum conditions observed by the earlier Ionospheric Occultation Experiment (IOX – 2001-2004). Scintillation can cause outages in HF through L-band communications systems.

    6. 6 Spectral Analysis of High Rate Data CORISS makes routine observations at high rate (50 Hz) during occultations when the LEO-GPS raypath tangent altitude is at ionospheric altitudes (100-800 km). This is something that no other occultation sensor doing. This high rate data can be spectrally analyzed to investigate the irregularity scale sizes present in the ionosphere. The Fresnel scale is evident in the power spectral density plot (right) derived from the high rate SNR observations. The location of the knee of the curve is dependent on the distance to the irregularity region, which may provide a method for more precisely geolocating these regions. CORISS is also testing out on-board algorithms for scintillation parameter determination.CORISS makes routine observations at high rate (50 Hz) during occultations when the LEO-GPS raypath tangent altitude is at ionospheric altitudes (100-800 km). This is something that no other occultation sensor doing. This high rate data can be spectrally analyzed to investigate the irregularity scale sizes present in the ionosphere. The Fresnel scale is evident in the power spectral density plot (right) derived from the high rate SNR observations. The location of the knee of the curve is dependent on the distance to the irregularity region, which may provide a method for more precisely geolocating these regions. CORISS is also testing out on-board algorithms for scintillation parameter determination.

    7. 7 COSMIC Validation Work

    8. 8 Ionospheric Climatology from COSMIC Data This is from the Lei et al. COSMIC ionospheric validation paper, which includes publication of the retrieval algorithm by Syndergaard. The plots compare COSMIC measurements of the peak density and altitude in the equatorial ionization anomaly to: an empirical model (International Reference Ionosphere) (IRI) a numerical model (NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model) (TIEGCM).This is from the Lei et al. COSMIC ionospheric validation paper, which includes publication of the retrieval algorithm by Syndergaard. The plots compare COSMIC measurements of the peak density and altitude in the equatorial ionization anomaly to: an empirical model (International Reference Ionosphere) (IRI) a numerical model (NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model) (TIEGCM).

    9. 9 Non-Migrating Tidal Structure in the Equatorial Ionosphere TEC in 50 km altitude intervals observed by COSMIC during 20-22 LT, autumnal equinox, 2006.TEC in 50 km altitude intervals observed by COSMIC during 20-22 LT, autumnal equinox, 2006.

    10. 10 Annual Asymmetry in the Ionosphere This is from Zhen Zeng’s work on the annual asymmetry in the ionosphere. On a global scale, ionospheric densities are higher during northern hemisphere winter than during northern hemisphere summer. This is caused by a combination of the magnetic field tilt and seasonal differences in composition.This is from Zhen Zeng’s work on the annual asymmetry in the ionosphere. On a global scale, ionospheric densities are higher during northern hemisphere winter than during northern hemisphere summer. This is caused by a combination of the magnetic field tilt and seasonal differences in composition.

    11. 11 Neutral Winds derived from COSMIC Data We can derive neutral winds in the thermosphere (near 300 km) from COSMIC data by measuring changes in the height of the peak of the F2-layer (hmF2) which are caused by winds pushing ions up and down the magnetic field lines. This work by Xiaoli Luan compares COSMIC wind measurements to modeling by the TIE-GCM.We can derive neutral winds in the thermosphere (near 300 km) from COSMIC data by measuring changes in the height of the peak of the F2-layer (hmF2) which are caused by winds pushing ions up and down the magnetic field lines. This work by Xiaoli Luan compares COSMIC wind measurements to modeling by the TIE-GCM.

    12. 12 Observations from the Halley Bay Ionosonde

    13. 13 Mapping the Weddell Sea Anomaly Alan Burns is studying the southern hemisphere ionization phenomenon known as the “Weddell Sea Anomaly”. (The Wedell Sea is the region off the coast of Antarctica east of the Antarctic Peninsula.) This area of unexpected ionization appears in the evening during quiet geomagnetic conditions and appears to be morphologically linked to the equatorial ionization peaks.Alan Burns is studying the southern hemisphere ionization phenomenon known as the “Weddell Sea Anomaly”. (The Wedell Sea is the region off the coast of Antarctica east of the Antarctic Peninsula.) This area of unexpected ionization appears in the evening during quiet geomagnetic conditions and appears to be morphologically linked to the equatorial ionization peaks.

    14. 14 Southern Summer — The Synoptic View Shaded line=terminator, dotted line=magnetic equator, interrupted dashed line = conjugate terminator. Bins are 25 degree longitude, 5 degrees latitude. Data are from 15 Oct to 15 Feb, 2006-2007 and 2007-2008.Shaded line=terminator, dotted line=magnetic equator, interrupted dashed line = conjugate terminator. Bins are 25 degree longitude, 5 degrees latitude. Data are from 15 Oct to 15 Feb, 2006-2007 and 2007-2008.

    15. 15 The 2006 “AGU Storm”

    16. 16 Geomagnetic Storm Disturbances

    17. 17 Data Sampling

    18. 18 COSMIC — The Next Generation

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