Global model comparison with Millstone Hill during September 2005

Abstract

A direct comparison between simulation results from the Global Ionosphere Thermosphere Model (GITM) and measurements from the Millstone Hill incoherent scatter radar (ISR) during the month of September 2005 is presented. Electron density, electron temperature, and ion temperature results are compared at two attitudes where ISR data is the most abundant. The model results are produced, first using GITM running in one dimension, which allows comparison at the Millstone Hill location throughout the entire mouth. The model results have errors ranging from 20% to 50% over the course of the month. In addition, the F2 peak electron density (NmF2) and height of the peak (HmF2) are compared for the month. On average the model indicates higher peak electron densities as well as a higher HmF2. During the time period from 9 September through 13 September, the trends in the data are different than the trends in the model results. These differences are due to active solar and geomagnetic conditions during this time period. Three-dimensional (3-D) GITM results are presented during these active conditions, and it is found that the 3-D model results replicate the trends in the data more closely. GITM is able to capture the positive storm phase that occurred late on 10 September but has the most difficulty capturing the density depletion on 11 and 12 September that is seen in the data. This is probably a result of the use of statistical high-latitude and solar drivers that are not as accurate during storm time. Copyright 2008 by the American Geophysical Union.