It should be noted that because of the delay in the avionics switch described above, five of the six UPS aircraft have had their WVSS units running for over a year without any recalibration. Table 1 below summarizes the installation dates and data availability of the six UPS aircraft. The actual tail numbers have been replaced with pseudo ID's per the agreement with the air carriers in sharing their data on the Internet.
Table 1. Period of Operations of the UPS B-757 Cargo Aircraft Equipped with the WVSS
Pseudo ID | Installation Date | Status (1 April 2000) |
00378 | 02/04/99 | Unit switched to Teledyne, Jan 2000. |
00376 | 02/06/99 | Working |
00441 | 02/12/99 | Working |
00714 | 04/01/99 | Working |
00097 | 04/15/99 | Working |
00375 | 09/02/99 | Working |
All meteorological data (winds, temperatures, and water vapor information) from commercial aircraft are available in real time via the Aircraft Communication Addressing and Reporting System (ACARS). Details of this system can be found in Appendix B. This information is available now on the Internet and soon will be available at the National Center for Environmental Prediction (NCEP). Dewpoint information on the Internet has been corrected (see Appendix A), however, mixing ratio information on the Internet provided by NOAA's Forecast System Laboratory (FLS) has not been corrected and is, on average, about 5% too wet.
This WVSS-I data is also distributed on the UNIDATA NETCDF local data manager (LDM). However, we caution the user about the quality of this data. Not only is mixing ratio information inconsistent with the dewpoint information (see above), there appears to be occurrences of missing data, data with no dewpoints, and inappropriate Mach number fields.
Researchers are encouraged to use the quality-controlled WVSS-I data through UCAR's Joint Office for Science Support (JOSS). This data is available through CODIAC at http://www.joss.ucar.edu/codiac/. This data has consistent water vapor information (dewpoint, RH, and mixing ratio are consistent), and has the benefit of time continuity to check for changes in WVSS-I calibration. Recall from above that these units have been flying for twice as long as expected without the ability to remove the units and recalibrate the sensors. This will be rectified as the new Teledyne avionics are installed. The fleet of WVSS-I aircraft will fly as a "system test" for about 1.5 - 2 years after the last aircraft is installed. After that time, the WVSS-I units will be replaced with the second generation WVSS (WVSS-II).