Abstract
AbstractCombining ocean model data and in situ Lagrangian data, I show that an array of surface drifting buoys tracked by a Global Navigation Satellite System (GNSS), such as the Global Drifter Program, could provide estimates of global mean sea level (GMSL) and its changes, including linear decadal trends. For a sustained array of 1,250 globally distributed buoys with a standardized design, I demonstrate that GMSL decadal linear trend estimates with an uncertainty less than 0.3 mm yr−1 could be achieved with GNSS daily random error of 1.6 m or less in the vertical direction. This demonstration assumes that controlled vertical position measurements could be acquired from drifting buoys, which is yet to be demonstrated. Development and implementation of such measurements could ultimately provide an independent and resilient observational system to infer natural and anthropogenic sea level changes, augmenting the ongoing tide gauge and satellites records.
Highlights
Modern global mean sea level (GMSL) rise is an intrinsic measure of anthropogenic climate change
This study aimed to demonstrate that the global drifter array could provide a third means—in addition to satellite altimetry and tide gauges—to monitor GMSL changes related to climate processes, provided that drifters are tracked using carefully controlled Global Navigation Satellite System (GNSS) technologies
A third observational system to measure mean sea level would be greatly beneficial to further validate and calibrate the existing observing systems, as well as refine the closing of the sea-level budget, and provide a redundancy in case of failure of the existing systems
Summary
Modern global mean sea level (GMSL) rise is an intrinsic measure of anthropogenic climate change. The technical limitation of this study is that it is assumed that altitude measurements with sufficient accuracy can be acquired regularly from relatively small buoys drifting at sea [the GPS receivers currently in use have an overall estimated horizontal accuracy of 22 m (Elipot et al, 2016)] This requires that enough computing power is present onboard each drifter to regularly calculate and transmit an accurate 3D position solution, or that time series of high frequency position data (typically at 1 Hz) could be transmitted intermittently to land for post-processing. Variance in daily MSL from hourly heights acquired by drifters will arise from relevant physical processes not represented by the model of the GLORYS2V4 ocean reanalysis: SSH variability from barotropic tides, internal waves including baroclinic tides, and surface gravity waves
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