A new network of altimetry-based virtual stations for measuring sea level along the world coastlines
Event: 2022 Ocean Surface Topography Science Team Meeting
Session: Science I: Climate data records for understanding the causes of global and regional sea level variability and change
Presentation type: Type Oral
Until recently, classical radar altimetry could not provide reliable sea level data within 10 km to the coast. However dedicated reprocessing of radar waveforms together with geophysical corrections adapted for the coastal regions now allows to fill this gap at a large number of coastal sites. In the context of the ESA Climate Change Initiative (CCI) Sea Level project, we have recently performed a complete reprocessing of along-track, high resolution (20 Hz, i.e. 300m resolution along-track) altimetry data of the Jason-1, Jason-2 and Jason-3 missions over 2002-2020 along the coastal zones of Northeast Atlantic, Mediterranean Sea, Africa, North Indian Ocean, Southeast Asia, Australia, and America. This reprocessing has provided valid sea level data in the 0-15 km band from the coast. A total of 773 altimetry-based virtual coastal stations (distance <6 km from coast) have been selected for all regions. Sea level anomaly time series, together with associated coastal sea level trends, have been computed over the 2002-2020 time span. In the coastal regions devoid from tide gauges (e.g., African coastlines), these virtual stations offer a unique tool for estimating sea level change close to the coast (typically up to 3 km to the coast, but in many instances up to 1 km or less). Results show that at about 20% of the 773 selected sites, coastal sea level trends are either larger or smaller in the last 4-6 km to the coast compared to open ocean sea level trends. Understanding such a behavior will need further investigation.