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Abstract
Measured and calculated values of electron concentration, electron temperature and ion temperature in the low- and mid-latitude ionosphere are presented and discussed.
The existence of horizontal, spatial gradients in electron temperature on 13 September 1980 above Arecibo, Puerto Rico is shown. The gradients were northward with maximum values of about 1.5 K km('-1).
The ionosphere model presented by Young et al. (1979) was tested by comparison with another theoretical model and with observations. The tests show that the model values of electron concentration are in agreement with the observations, but that the model electron temperatures are too low. An increase in the model electron heating rate by a factor of 1.5 to 4 is shown to result in better agreement. The suggestion is made that the photoelectron transport equations are incorrect in calculating the photoelectron flux at low energies. The possibility of an error in the electron cooling rate due to interactions with positive ions could not be ruled out.
The model is used to explain the observed electron temperature gradients. By assuming the existence of a poleward meridional neutral wind with a poleward velocity gradient, it is shown that the resulting change in the height of the F-region causes differences in electron temperature such as those observed at Arecibo on 13 September 1980.
Comparisons of simultaneous measurements from the Arecibo and Millstone Hill observatories are presented. These observations show that significant differences existed in the electron temperature as a function of latitude on 27 June 1981. The results from Arecibo (18(DEGREES)N geographic latitude) were indicative of a local-cooling dominated F-region, while the Millstone Hill results showed that at geographic latitudes of 31(DEGREES) to 37(DEGREES), the F-region was transport dominated. These observations again are explained by using the model with a poleward wind which increases in velocity with increasing latitude. Observations on 22-23 March 1981 provided the first simultaneous measurements of electron temperature and concentration at two points along a magnetic field line using ground-based techniques.
Model calculations of protonospheric ion fluxes are presented and discussed.
