Systematic Observations of High Latitude Dynamics in the Mesosphere and Lower Thermosphere (MLT) From Orbit

Synoptic observations from space of high latitude neutral dynamics have become routine with the limb-viewing TIDI instrument launched aboard TIMED in December 2001. Prior to TIMED, space based observations of neutral winds in the MLT at the highest latitudes have been restricted by a lower satellite inclination angle1. Observations of the MLT winds are now available for the declining phase of the solar cycle from early 2002 to present. This paper will describe new results from TIDI of the daily and annual variation of the high latitude neutral horizontal wind. A long-term program has been in operation at S\o ndre Str\o mfjord Greenland to monitor neutral winds in the lower thermosphere using the OI (5577Å) emission as the diagnostic (1987-present). These data have shown a strong semi-diurnal periodicity in the horizontal neutral wind. Combining the winds from orbit and from S\o ndre Str\o mfjord permits the characterization of the dynamics in the Arctic MLT for the period 2002 to present. Wind patterns for each northern winter season since 2002 will be compared in this paper. 1S. P. Zhang and G. G. Shepherd, Neutral winds and O(1S) emission rates in the lower thermosphere as measured with WINDII/UARS during the April 4-5th 1993 and February 1994 geomagnetic storms, J. Atmos. Solar-Terr. Phys., 64, 1201, 2002.