Comparison of the MSIS and Jacchia-70 Models with Measured Atmospheric Density Data in the 120 to 200 km Altitude Range

摘要

The MSIS and Jacchia-70 (J70) models have been evaluated at each of the nearly 55,000 points for which we have measurements of the atmospheric density between 120 and 200 km. The density measurements were made by nine different instruments of five types (ion gauge, capacitance manometer, mass spectrometer, calorimeter, and accelerometer) flown of five satellites during the 1974-1977 solar minimum. Except for the solar flux, all the parameters used in the models (geomagnetic activity, altitude, latitude, local time, season, etc.) were well represented. The density measurements at any one altitude were found to be consistent with a lognormal distribution; that is, the fractional variations in the density were normally distributed, rather than the variations themselves. If a model correctly predicted the average variation in density, the log of the ratio of the measurements to the predictions should be normally distributed with skewness of 0.0 and kurtosis of 3.0. In fact, the skewness when the J70 model was used was -0.10 and the kurtosis was 3.51. For the MSIS model, the corresponding numbers were -0.06 and 4.42.