Millstone Hill Thomson Scatter Results for 1969

This report summarizes the results for the electron-density distribution, electron and ion temperatures, and vertical ionization fluxes in the F-region obtained during 1969 using the Millstone Hill (42.6°N, 71.5°W) Thomson (incoherent) scatter radar system. These data, for the height interval approximately 200 to 900 km, were gathered over 24-hour observing periods, roughly twice per calendar month. The time resolution to obtain results over this entire height interval was either 30 or 45 minutes, depending upon which of two operating modes was employed. The results for the diurnal variation of the electron density and temperature exhibit the characteristic summer and winter patterns discussed previously. The transition between the two takes place in April and October. Two cases of overhead auroral precipitation were observed during the year as a consequence of efforts to observe a stable red arc. Other instances of geomagnetically disturbed behavior were infrequent. Vertical fluxes of ionization were measured, and the flux escaping to the magnetosphere near midday was found to have an average value of ~5 x 10[superscript 7] el/cm[superscript 2]/sec. Near midnight, the magnetosphere appears to supply the local ionosphere with a flux of about half this amount.