How accurate is accurate enough?

Benoit Meyssignac (CNES/LEGOS, France)

Event: 2019 Ocean Surface Topography Science Team Meeting

Session: OSTST Opening Plenary Session

Presentation type: Type Keynote/invited

After 26 years of research and development, the sea level estimates derived from satellite altimetry measurements have reached a level of maturity that is unprecedented. Among the ECVs measured from space, sea level is arguably one of the most advanced with a quasi global coverage, a very low ratio of missing or corrupted data, an advanced estimate of the uncertainties which accounts for the time-correlation in errors, a robust validation (through both the comparison with tide gauge records and the closure of the sea level budget) and a very high accuracy which exceeds the altimetry missions’ requirements. This level of maturity make wonder about the real need of further research to improve the sea level record and in particular the sea level estimates’ accuracy. Simply put the question gets down to: How accurate is accurate enough? This question is important for the ocean surface and topography science team as a significant amount of resources is currently used to keep on improving the sea level record accuracy.
In this presentation I explore the question of the accuracy that should be targeted in satellite altimetry. I review the literature and summarize the current scientific questions associated to the sea level science. For each scientific question I analyse the litterature and derive from recent papers the level of accuracy in sea level estimates that is needed to tackle the question. I focus on climate science questions as climate science is arguably the field that needs the highest level of accuracy in sea level estimates. I find that four major science questions need an accuracy in sea level or in its contributions that is close or higher than the current available accuracy. These questions are the closure of the sea level budget, the estimate of the Earth energy imbalance, the observational constraint on projections of future sea level and the estimate of sea level rise in coastal zones. With this list of science questions and the level of accuracy they require from sea level observations, I am able to propose to the OST science team and the satellite program managers a simple answer to the question “How accurate is accurate enough?”. This answer is: Tell me which scientific question you want to tackle in the list and I will tell you how accurate is accurate enough?
 

Keynote/invited presentation show times:

Room Start Date End Date
The Forum Mon, Oct 21 2019,12:00 Mon, Oct 21 2019,12:20
Benoit Meyssignac
CNES/LEGOS
France
benoit.meyssignac@legos.obs-mip.fr