Comparisons of JOULE 1 rocket thermospheric wind observations in high latitudes with GITM simulations

Abstract

The JOULE sounding rocket 1 experiment was carried out at Poker Flat Research Range in Alaska around 1200 UT on March 27th, 2003 with two instrumented rockets and one chemical tracer rocket. From the released trimethyl aluminum (TMA) trails, neutral wind measurements showed a wind peak at 120 km altitude and a jet structure around it, which were superposed by a vertically propagating wave. Running global ionosphere thermosphere model (GITM) with a stretched grid structure, sub-degree resolution around the JOULE rocket position was applied. Data-model comparison shows that the GITM simulation reproduced the large neutral wind at 120 km altitude. The simulation also shows a strong vertical wind shear below 120 km, which is generally consistent with observation but with a smaller gradient. The primary discrepancies were the wave features below 115 km and the wind gradient above 120 km altitude, which indicates that the wave forcing besides the ion-drag force plays an important role to the neutral dynamics in the lower thermosphere. The comparison between simulations using different high-latitude drivers was also conducted to emphasize the significance of the electrodynamics to the neutral wind. Using assimilative mapping of ionospheric electrodynamics (AMIE) procedure as the high latitude driver produced more accurate neutral wind patterns than using Weimer empirical model.