Improved Timing Calibration of QuikSCAT

Since being launched in June 1999, QuikSCAT has successfully and accurately measured ocean wind vectors. Current research is attempting to increase performance beyond the original design parameters in order to increase the utility of the data. Timing calibration is critical to this effort. Timing information is used to determine instrument performance as well as to calculate the location of each measurement on the Earth’s surface. This paper reports a method of obtaining high-precision time validation measurements through the use of the QuikSCAT Calibration Ground Station (CGS). The QuikSCAT CGS passively records satellite transmissions as it passes overhead. Analysis of CGS data can determine the arrival time of each QuikSCAT pulse to within microseconds. Utilizing the high stability of the onboard pulse repetition interval clock, along with CGS observations, precise instrument timing can be determined during a portion of the orbit, which enables more precise determination of the timing throughout the entire orbit. The improved timing is able to support the requirements of advanced data applications.