WP1. Sea-level governing processes during present times and predictability

Inputs

Multi-platform data from (i) remote-sensing (satellite altimetry and gravimetry data), (ii) in-situ (tide-gauge, vertical profiles from hydrographic stations and Argo profiling floats), (iii) global/regional ocean/atmospheric re-analysis and numerical experiments, (iv) climate models.

Description

This WP focuses on the regional drivers of sea-level variability (e.g. at the northern high latitudes) during the last three decades building on new observing capabilities from remote-sensing and their synergy with in-situ measurement and model-based information. Multi-platform data will be collected over a period spanning the satellite era (early 1990s – present; Task 1.1). This information will be then used in a sea-level budget analysis, in particular focusing on the steric and mass components and on different atmospheric and oceanic processes (e.g., ocean heat content, SML), to assess how/if new observing capabilities allow constraining the sea-level variability at the northern high latitudes (Task 1.2). A novel approach will be applied using remote-sensing, in-situ data, and reanalysis together with machine learning/AI methods to understand the 3D mesoscale contributions to ocean dynamics/thermodynamics and their interaction with the atmosphere and cryosphere which in turn affect sea level variability (Task 1.3).

The output of this Task will serve as a reference for assessing the impact of eddies on sea-level projections in WP3. Seasonal-to-decadal hindcast simulations with NorCPM will be evaluated against optimal data-sets from Task 1.1 and budget analysis from Task 1.2 to provide a lower limit for sea-level predictability and to identify shortcomings in NorCPM’s process representations relevant for sea-level prediction; the skill will be enhanced with an optimal filtering method developed at NERSC, informed by sea level observations and NAO predictions; hindcast simulations initialised from NorESM pacemaker simulations, and analogue predictions based on uninitialised climate simulations will provide additional benchmarks; effects of potential volcanism and induced oceanic imprints [18, 19] on annual-to-multidecadal sea-level predictability will be assessed (Task 1.4).