TAMDAR aircraft impact experiments with the Rapid Update Cycle

As part of the NASA sponsored Great Lakes Fleet Experiment (GLFE) with experimental TAMDAR observations, FSL has conducted real-time parallel experiments with hourly RUC cycle to test the impact of these data. FSL's RUC experiments have used up-to-date assimilation/model techniques (generally corresponding to the new 13km RUC, but run at 20km resolution), complete assimilation of all observation types (as used in the RUC13, including cloud analysis (GOES and METAR), full METAR assimilation with effects of boundary-layer depth, GOES precipitable water, all other aircraft, profiler (NOAA and CAP), and rawinsonde). With its hourly assimilation and full use of other observations, the RUC provides a well-qualified assessment environment for the TAMDAR data. The forecast experiments were strictly controlled to isolate the effects of TAMDAR data, including even a resetting of common initial conditions every 48h to ensure a full control.

Forecast skill in these parallel RUC cycles with and without TAMDAR data has been evaluated by verification Initial results have shown a positive impact in the lower troposphere, especially near 850 mb, especially for temperature, and to less degree for humidity and winds. The results have varied over time due to variations in resolution, quality procedures for data, and geographical and diurnal variations in data density. The TAMDAR RUC experiments have helped, along with the case study investigations discussed by others, to identify initial TAMDAR problems and improve the data quality.

The design and latest results from the TAMDAR RUC impact experiments will be described in the proposed presentation.