Retrieved temperature and moisture parameters from the GOES-8/10 sounders are currently processed in real time at hourly intervals for cloud free fields of view (FOV). Spatial resolutions of approximately 30 km (3 by 3 FOV) for temperature and water vapor profiles are routinely available. Clear FOVs are required for the proper conversion of measured radiances to standard meteorological parameters. The lack of clouds in these clear FOVs implies that a predominantly adiabatic state exists. Thermodynamic properties in these clear regions, at levels above the boundary layer, should remain relatively constant along isentropic trajectories.

An experiment is proposed to assess the temporal degradation of retrieved thermodynamic parameters from the GOES sounders. An analysis system based on a recursive filter is configured to use current retrievals as well as past retrievals that have been projected forward in time along isentropic trajectories to new locations. The quality of the projected retrievals are continually evaluated by comparing them against current retrievals and are down-weighted when their validity becomes questionable. Isentropic trajectories are computed using winds from the Rapid Update Cycle (RUC) forecast model, which uses an isentropic vertical coordinate. Preliminary assessments indicate that retrievals of temperature and water vapor maintain reasonable accuracy for three to six hours after the observation time. If three observation times are maintained in each analysis it represents approximately a three-fold increase in the number of contributing observations. In addition, areal coverage and horizontal resolution increase slightly. The ability of the system to resolve horizontal gradients of atmospheric stability is evaluated by comparing consecutive analyses to stability indices derived from GOES sounder radiances.