Project title

Sea Level Climate Change Initiative

Overview

The main objective of the sea level CCI project is to produce and validate a Sea Level Essential Climate Variable (ECV) product. It represents the first phase of the ESA Climate Change Initiative program that aims at setting up in a second phase an "operational processing capacity of Earth Observation data"

Description

Sea Level Overview

Sea level is a very sensitive index of climate change and variability. As the ocean warms in response to global warming, sea waters expand and, as a result, sea level rises. When mountain glaciers melt in response to increasing air temperature, sea level rises because more freshwater glacial runoff discharges into the oceans. Similarly, ice mass loss from the ice sheets causes sea-level rise. The increase of freshwater flowing into the oceans reduces its salinity, decreasing its density and affecting ocean circulation patterns that in turn affect sea level and its spatial variability.

The global mean level of the oceans is an indicator of climate change. It incorporates the reactions from several different components of the climate system. Precise monitoring of changes in the mean level of the oceans is vitally important for understanding not just the climate but also the socioeconomic consequences of any rise in sea level.

How it is measured

Past variations can be reconstructed from several indicators, but the very first measurements of sea level were made by monitoring tides in the 18th century. Although we now have a relatively dense network of tide gauges, only 20 stations, mostly along the coasts of Europe and North America, collected data throughout the 20th century. On the basis of their measurements, sea level is estimated to have risen by 10 to 20 centimetres since 1900.

Today, satellite altimetry, autonomous floats (Argo floats since 2003) and gravimetry data (Grace satellite) enable to measure Mean Sea Level variations, or some of their components. Ocean models are also used to understand and quantify those phenomena.

With the satellite altimetry missions, the global mean sea level (GMSL) has been calculated on a continual basis since January 1993. 'Verification' phases, during which the satellites follow each other in close succession (Topex/Poseidon & Jason-1 then Jason-1 & Jason-2), help to link up these different missions by precisely determining any bias between them. Envisat, ERS-1 and ERS-2 are also used, after being adjusted on these reference missions, in order to compute Mean Sea Level at high latitudes (higher than 66°N and S), and also to improve spatial resolution by combining all these missions together. In addition, permanent monitoring of quality during the missions and studies of the necessary corrections of altimetry data regularly add to our understanding and knowledge.

Products

The main objective of the sea level CCI project is to produce and validate a Sea Level Essential Climate Variable (ECV) product. It represents the first phase of the ESA Climate Change Initiative program that aims at setting up in a second phase an “operational processing capacity of Earth Observation data”.

Version 1 of Sea-Level ECV products has been produced over a 1-year period: from January 1993 to December 1993. Currently only the monthly grids of Sea level anomalies (in agreement with the PSD document) have been produced and are available on the slcci ftp site. The time series will be completed over all the period (18 years) before September 2012. The  Sea-Level ECV indicators (as the global and regional Mean Sea level trends) will also be produced in September 2012.

Partners

CLS - prime contractor and Sea Level CCI consortium lead. Responsible for the overall project management as well as leading the technical activities that are related to the development and test of the algorithms (WP2000) and the sea level ECV production (WP 3000).

DTU Space- involved in the improvement  and assessment of the altimeter processing  in high latitudes (WP2000).

ECMWF - will validate the sea level ECV products by leading assimilation and comparison with their ocean climate model

GFZ - will provide to the consortium a homogenised series of new orbits for all the missions (WP2000).

isardSAT - involved in a specific task dedicated to the improvement of the instrumental processing of ESA missions (WP2000).

LEGOS- will support the science leader and will lead a validation study based on the sea level closure budget.

Logica - bringing its industrial experience in operational system engineering (WP5000) and project management in coordination with CLS.

NERSC - will validate the sea level ECV products by leading comparison studies with their coupled BCM model

UoH - responsible for the climate modelling group and will manage the interface with the CMUG group with the science leader. UoH will also validate the sea level ECV using their ocean models.

This page has no comments.