An intercomparison of VLF and sounding rocket techniques for measuring the daytime D region ionosphere: Theoretical implications
Abstract
We compare the two approaches that have been used to measure the lowermost ionosphere, the measurement of the propagation of very low frequency (VLF) radio waves and the in-situ sampling by sounding rockets. We focus on the altitude, latitude and zenith angle variation of the electron density profiles inferred from these two observational techniques as compared with a theoretical photochemical model. Our results show that below 68-70 km, the VLF data and the model agree better with each other than with the sounding rocket profiles. At the lowest altitudes, near 60 km, both the VLF data and the model show a greater electron density at higher latitudes, consistent with a cosmic ray flux that increases with latitude, whereas the limited rocket data show a maximum at the tropics. Above 68-70 km, the VLF data and the sounding rockets agree better and at tropical latitudes, the model fails to reproduce the observations. Specifically, the calculated electron density is lower than the data by up to a factor of two. Possible reasons for the model deficit include underestimates of the solar Lyman alpha flux, the solar X ray flux and the mesospheric nitric oxide density. Once these three factors are mitigated, the model is in agreement with the observations between 60-80 km.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSA31C3445S
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0340 Middle atmosphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3303 Balanced dynamical models;
- ATMOSPHERIC PROCESSESDE: 3332 Mesospheric dynamics;
- ATMOSPHERIC PROCESSES