CoAuthors

Brian Beckley (NASA Goddard Space Flight Center, USA); John Fasullo (NCAR, USA); Ben Hamlington (Old Dominion University, USA); Dallas Masters (University of Colorado, USA); Gary Mitchum (University of South Florida, USA)

Over the last 25 years, data from TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 have been used to observe changes in global mean sea level (GMSL). A rate of rise of ~3 mm/year has been observed. However, observing a possible acceleration in the rate of sea level rise is more challenging and pushes the limits of the observing system accuracy. This presentation will examine our first attempts at detecting an acceleration in the altimeter sea level record. First, the errors in the altimetry will be discussed in the context of tide gauge validation of the altimeter sea level record, including new improvements to the TOPEX record. We will discuss the influence of interannual variability in GMSL on acceleration estimates and how this influence can be mitigated. We will also discuss the role of decadal variability and how it might influence the determination of acceleration, including the role that the 1991 eruption of Mount Pinatubo had on the altimeter sea level record. Finally, we will present an estimate of the climate-driven acceleration of GMSL over the 25-year record, including the importance of using the tide gauge validation to place an error bar on the acceleration estimate.