F{sub 2} peak electron density at Millstone Hill and Hobart: Comparison of theory and measurement at solar maximum
- Univ. of Alabama, Huntsville, AL (United States)
- Univ. of Massachusetts, Lowell, MA (United States); and others
This paper compares the observed behavior of the F{sub 2} layer of the ionosphere at Millstone Hill and Hobart with calculations from the field line interhemispheric plasma (FLIP) model for solar maximum, solstice conditions in 1990. During the study period the daily F{sub 10.7} index varied by more than a factor of 2 (123 to 280), but the 81-day mean F{sub 10.7} (F{sub 10.7A}) was almost constant near 190. Calculations were performed with and without the effects of vibrationally excited N{sub 2} (N{sub 2}*) which affects the loss rate of atomic oxygen ions. In the case without N{sub 2}* there is generally good agreement between the model and measurement for the daytime, peak density of the F region (NmF{sub 2}). Both the model and the measurement show a strong seasonal anomaly with the winter noon densities a factor of 3 to 4 greater than the summer noon densities at Millstone Hill and a factor of 2 greater at Hobart. The seasonal anomaly in the model is caused by changes in the neutral composition as given by the mass spectrometer and incoherent scatter (MSIS) 86 neutral density model. While N{sub 2}* worsens the model-data comparison at Millstone Hill, it does bring the model seasonal density ratio into better agreement with the data and also improves the agreement at Hobart. Although the 1990 daytime ionosphere can be well modeled without N{sub 2}*, it may still be important for high levels of solar and magnetic activity. There is a very close relationship between the height at which peak density occurs hmF{sub 2} variation and the NmF{sub 2} variation with F{sub 10.7} in summer at Millstone Hill. The international reference ionosphere (IRI) model generally provides a good representation of the average behavior of noon NmF{sub 2} and hmF{sub 2} but because the data show a lot of day-to-day variability, there are often large differences. The FLIP model is able to reproduce this variability when hmF{sub 2} is specified. 28 refs., 16 figs.
- OSTI ID:
- 102614
- Journal Information:
- Journal of Geophysical Research, Vol. 99, Issue A8; Other Information: PBD: 1 Aug 1994
- Country of Publication:
- United States
- Language:
- English
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