Comparison of thermospheric density models by satellite orbital decay analysis

Some of the most widely used thermospheric density models (JR-71, MSIS-86, MSISE-90, TD-88) were compared, by analyzing the decay histories of nine satellites. The satellite sample and the time interval examined encompassed a broad range of altitudes (200-1500 km) and solar activity levels (1987-1999). The MSIS models, practically identical above 200 km, resulted to be the best ones to compute air density below 400 km, in low solar activity conditions. JR-71 seemed to be more accurate at greater altitudes and/or solar fluxes. TD-88 gave quite mixed performances, but generally closer to the JR-71 results. The intrinsic accuracy of JR-71, MSIS-86 and MSISE-90 was generally better than 20%, and sometimes close to 10%. This picture resulted progressively degraded at altitudes greater than 400 km.