Ion composition data from the Defense Meteorological Satellite Program (DMSP) F10 have been averaged by geographic longitude and dip latitude for the months of June, September, and December 1993. The data were taken under near solar minimum conditions. Near 800 km at two fixed local times near 0920 hours and 2120 hours, and at all longitudes, significant variation in local time and season are found. Longitude variations are consistent with modulation of the F peak height by meridional and zonal neutral winds. The components of these winds parallel to the magnetic field lines act to raise and lower the height of the F peak and, additionally, at night, to modulate the plasma decay rate. Zonal winds were found to have significant effects in the longitude regions 150°E to 270°E and 300°E to 360°E, where the magnetic declination is significant. Under solstice conditions, the summer to winter meridional winds play a dominant role in regulating the F peak height, with the zonal winds enhancing or opposing the effects of the meridional winds at longitudes with significant magnetic declination. Zonal winds dominate the regulation of the F peak height near equinox, when the meridional winds are fairly symmetric about the dip equator. The longitude variations are most clearly seen in the O+ and H+ concentrations when O+ is the dominant ion and is in equilibrium with H+. These conditions were found during the daytime during all seasons. H+ is frequently the dominant ion near 800 km, and at night, the longitudinal variations clearly seen in the O+ concentrations were not as easily seen in the H+ concentrations due to the larger scale height of H+.

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[1] Solar eclipses are known to locally disrupt the transport, production, and loss mechanisms in the ionosphere. Ion composition, ion temperature, and neutral temperature data from the Atmosphere Explorer E spacecraft are examined for the total solar eclipse of 16 February 1980. The spacecraft transited twice across the dayside face of the Earth during the course of the eclipse, allowing for examination of eclipse effects to be made over a wide longitude and local time range and for examination of posteclipse recovery of the ionosphere. One orbit from 14 February, occurring over a longitude and local time range similar to that of the first eclipse orbit, is used as control data. The eclipse had a significant effect on the concentrations of both O + and N + , which both dropped. The concentration of H + seems to show an eclipse effect, but the concentrations are too low to draw definite conclusions. Signatures of charge exchange between H + and neutral oxygen are seen in the data from the second eclipse orbit. The ion temperature drops by as much as 60 K. The neutral atmosphere shows no change in temperature during the course of the eclipse. The second eclipse orbit occurred closer to the path of the eclipse than did the first orbit, and the perturbations caused by the eclipse are greater in the second orbit. The control and second eclipse orbit data are compared to results from the International Reference Ionosphere 2000 model. The model results show good qualitative agreement with the ion concentration data.

We report conceptual inventory results of a large-scale assessment project at a large university. We studied the introduction of materials and instructional methods informed by physics education research (PER) (physics education research-informed materials) into a department where most instruction has previously been traditional and a significant number of faculty are hesitant, ambivalent, or even resistant to the introduction of such reforms. Data were collected in all of the sections of both the large algebraand calculus-based introductory courses for a number of years employing commonly used conceptual inventories. Results from a small PER-informed, inquiry-based, laboratory-based class are also reported. Results suggest that when PER-informed materials are introduced in the labs and recitations, independent of the lecture style, there is an increase in students' conceptual inventory gains. There is also an increase in the results on conceptual inventories if PER-informed instruction is used in the lecture. The highest conceptual inventory gains were achieved by the combination of PER-informed lectures and laboratories in large class settings and by the hands-on, laboratory-based, inquiry-based course taught in a small class setting.

[1] Average He + concentrations are examined for solar maximum conditions at equinox using data from Defense Meteorological Satellite Program (DMSP) flights F13 and F15. The DMSP spacecraft have Sun-synchronous orbits at 800 km altitude. F13 data were taken under presunrise conditions, while F15 data were taken at midmorning local times. Data are averaged for 31 days centered on the northern spring and fall equinoxes between ±40°m agnetic latitude. Both the He + concentration and He + fraction show significant longitudinal and latitudinal variation, which can be accounted for by neutral wind induced ion drag. The He + fraction can reach as much as 40% of the total plasma density in the presunrise hours, but 10% or less of the total plasma density at midmorning. While the He + concentrations before sunrise and at midmorning have comparable magnitudes, the midmorning values of the He + fraction are much more uniform than in the presunrise data. Examination of the F10.7 cm solar flux and geomagnetic activity implies solar flux has a much greater influence on He + concentrations. The level of solar flux as well as the amount of variability in the solar flux appear to influence the average He + concentrations and fractions.