Missing TAMDAR Data Resulting From Aircraft Icing.
Prepared by Gene Brusky, SOO NWS Green Bay
In this example, a TAMDAR ascent sounding beginning at 1427Z out of Houghton, MI (CMX) indicated considerable missing data from the surface to approximately 750 mb (Figure 1). This sounding (and all displays in this example) were generated via the FSL's Aircraft Data Display JAVA website. Radar (Figure 2) and satellite (Figure 3) data indicated that the aircraft was ascending through an area of mainly light snow associated with an area of warm air advection ahead of a weak short wave disturbance moving across Upper Michigan.
The flight path for this aircraft (#5594) is indicated in Figure 4. Note that if the user simply drags the cursor along any portion of the flight path, various data can be displayed including temperature, dew point, relative humidity and elevation. Icing information is also included. In this example, the number "4" next to the "ice:" designator indicates the aircraft is experiencing icing conditions. Icing information is also available via tabular format by right-clicking on the aircraft flight path in the plan view. Note the number "4" in the "Ice" column on the far right-hand side of the table (Figure 5). The "4" in this column indicated that the aircraft experienced icing conditions during its ascent from near the surface through about 5000 ft. When a TAMDAR-equipped aircraft experiences icing, it is required to turn on a heater associated with the sensor. Unfortunately this action will also tend to corrupt the data, thus it will be reported as missing. AIRDAT is aware of this problem and is working toward a solution. Remember that the purpose of the TAMDAR Great Lakes Fleet Experiment (GLFE) is to evaluate the new TAMDAR sensor, thus operational forecasters should expect to see occasional problems with the data during the experiment. The purpose of this example is simply to make forecasters (who utilize the FSL Aircraft website) aware of a common scenario in which missing data will appear in the soundings. Note that in AWIPS D2D, TAMDAR soundings containing considerable missing data, etc., as in this example, will not be displayable. The requirements for a "good" sounding to appear in AWIPS (via MADIS) are as follows:
A sounding is now considered "good" if:
- the lowest point is
within 50 nm of a known airport
- the lowest point is not higher than 2000 ft AGL
- no gap in altitude greater than 5000 ft exists
- the sounding extends to at least 1000 ft MSL
Note that the these requirements are in addition to routine QC of the aircraft data by AIRDAT.
Figure 1 (above) - TAMDAR ascent sounding from CMX
Figure 2 - KMQT radar reflectivity image at 14:58Z 01/25/05
Figure 3 - 1445 IR Satellite Image
Figure 4 (above) - Flight path for aircraft #5594 ascending out of CMX with data sampling.
Figure 5 (above) - Tabular data for aircraft #5594 obtained by right-clicking on the flight path displayed in Figure 4.
