CoAuthors

Born George (University of Colorado, USA); Shailen Desai (Jet Propulsion Laboratory, USA); Rashmi Shah (Jet Propulsion Laboratory, USA)

We describe the latest satellite radar altimeter calibration/validation (CALVAL) results from data collected at the Harvest offshore platform. Located about 10 km off the coast of central California near Point Conception, Harvest has hosted a dedicated altimeter CALVAL facility since the launch of TOPEX/POSEIDON (T/P) in August 1992. Harvest is directly in the path of the 10-d repeat ground track for the primary reference (Jason-class) altimeter missions, enabling the development of a continuous calibration record based on direct (overhead) passes of the platform. The experiment has produced a CALVAL time series spanning 23 years, enabling connection of the sea-level records from the T/P, Jason-1 and OSTM/Jason-2 missions.

For the current Jason-2 mission, we estimate the sea-surface height bias and drift are +10 ± 4 mm and +2 ± 1 mm/yr respectively (one standard error with N = 173). When we account for systematic error sources—such as uncertainty in the platform vertical position and velocity—these estimates are not statistically distinguishable from zero. We provide updates to these estimates that reflect the latest overflights, and also provide comparable estimates for T/P (based on new releases of retracked data) and Jason-1 (based on newly reprocessed geophysical data records).