Written by Andrea Prantner
30 January 2014
The continuous data collection of the HAR2 and HARV GNSS receivers on the Harvest oil platform plays a significant role in sea level monitoring. Station data started to degrade at the end of November 2013 for the HAR2 receiver. Upon inspection by the platform personnel it was found that both of the AC units that cool our equipment shack had failed, causing the GPS equipment to overheat. The back-up power system (UPS) and the station computer had failed as well. UNAVCO field engineer Andrea Prantner visited the platform on Jan 13th and 14th 2014 and successfully installed a new AC unit, a UPS and a new station computer. The temperature in the JPL equipment shack is once again stable and the equipment is up and running.
In addition to being used for drilling for oil, the Harvest oil platform is also an important international resource for the study of sea level from space. Two satellites currently in orbit fly over Harvest on a regular basis and record local sea surface height. Tide gauges attached to the platform continuously measure and record variations in sea level relative to the platform. Data from two GPS systems on the platform (HARV & HAR2) are used to calculate the absolute height of the platform relative to the Earth's center. Combining the tide gauge and GPS results gives the local sea-surface height relative to the Earth's center. This is the same quantity measured by the radar's altimeter each time the spacecrafts pass directly over the platform. The two sets of values are then compared, and any difference between these values would be considered calibration errors. Minimizing these errors is accomplished by having redundancy in instrumentation. For more information regarding this experiment, please see The Harvest Experiment.
We found that data quality is still an issue for both the HAR2 and HARV GPS receivers, and it appears the HAR2 receiver and antenna suffered permanent damage from the extreme temperatures in the equipment shack after the AC failure. A new receiver and antenna pair have been ordered and will be deployed during our next visit.
We would like to acknowledge and thank the personnel on the platform for the help they provided in bringing this station back online!
Last modified: Friday, 17-Jul-2015 17:45:56 UTC