Operations

GLFE AND RTFDDA Modeling

In the late 2004, a pilot demonstration TAMDAR field program over the Great Lakes area, named the Great Lakes Field Experiment (GLFE), was jointly conducted by NASA, NOAA/FSL, NWS (National Weather Services), FAA, NOAA, Mesaba Airlines and AirDat. During GLFE, AirDat equipped 63 Mesaba Airlines’ turboprop SAAB 340 aircrafts with TAMDAR sensors that measure both conventional meteorological variables including temperature, pressure, winds and humidity as well as icing, turbulence and GPS heights. In a typical day, these instrumented aircraft make about 400 flights a day, providing about 800 soundings at the regional and major airports in the region since Jan. 2005. At present, AirDat LLc, and NASA are in the process of enhancing TAMDAR sensors and implementing them onto more regional airlines.

To explore the potential of TAMDAR in improving regional short-term forecasts, a RTFDDA system was developed and has been operational on an AirDat Linux cluster. The forecast system has three domains, with 36, 12 and 4-km grid sizes respectively. The 12-km mesh covers all Mesaba Airlines regional flight airports and the neighboring regions affected by TAMDAR data.

In order to better resolve the regions of interest, a movable 4-km domain is nested in the 12-km domains. Owing to the limitation of the computation capability of the available cluster, the model system has been operated mostly with the two coarse domains (36/12-km) during GLFE.

Real-Time Modeling Products

Two identical forecast systems are running in parallel, with one system ingesting the extra TAMDAR data and the other using standard RTFDDA data only. Both systems are running in real-time with 3-hr cycles with 12-hr forecasts in each cycle. The boundary and the initial conditions at cold-starts are provided using NCEP NAM (North America Model) model data. A data quality control procedure based on Liu et al (2004) was adapted to assure TAMDAR data quality, which not only prescreened problematic and unrepresentative data, but also provided valuable information for real-time TAMDAR quality assurance upstream of the TAMDAR data collection and dissemination. The model products are provided in real-time to AirDat and others in the communities.

A comparison of the RTFDDA, RUC-13 and NAM 3-hour accumulation with the NCEP STAGE IV analysis, ending at 00Z 15 Aug. 2005. Dashed lines mark convective rain bands based on the STAGE IV rain analysis.