The investigators will build and deploy a set of critical instruments clustered around the Sondrestrom radar in Greenland. They will operate these instruments for a single extended campaign during the winter season in 1999. The instruments include three radio beacon receivers which will be built and deployed along with two existing receivers in Greenland to perform radio tomographic imaging of the E and F region ionosphere. During the experiment, simultaneous measurements of the E region neutral winds will be made by the incoherent scatter radar and a Fabry-Perot interferometer at Sondrestrom, Greenland. The local measurements will be put on a global context using computer models. Using this method, the investigators will measure the three dimensional spatial and temporal structure in the height-resolved Joule heating and determine the contribution of small scale variability in Joule heating and its impact on global atmospheric structure. The campaign will test and validate the instruments and show that high resolution Joule heating can be measured by this technique. The observations are important to CEDAR/TIMED science objectives. CEDAR, which stands for Coupling, Energetics, and Dynamics of Atmospheric Regions, is a global change program that combines theoretical modeling with ground-based measurements to study the upper atmosphere and ionosphere. TIMED, for Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics, is a NASA satellite program to study similar regions of the atmosphere. The joint CEDAR/TIMED program aims to coordinate ground-based and space-based observations to achieve better understanding of physical processes in the lower thermosphere and ionosphere.
