Articles | Volume 9, issue 2
Earth Syst. Sci. Data, 9, 557–572, 2017
Earth Syst. Sci. Data, 9, 557–572, 2017

Brief communication 14 Aug 2017

Brief communication | 14 Aug 2017

A new phase in the production of quality-controlled sea level data

Graham D. Quartly1, Jean-François Legeais2, Michaël Ablain2, Lionel Zawadzki2, M. Joana Fernandes3,4, Sergei Rudenko5,6, Loren Carrère2, Pablo Nilo García7, Paolo Cipollini8, Ole B. Andersen9, Jean-Christophe Poisson2, Sabrina Mbajon Njiche10, Anny Cazenave11,12, and Jérôme Benveniste13 Graham D. Quartly et al.
  • 1Plymouth Marine Laboratory, Plymouth, PL1 3DH, UK
  • 2CLS, 31520 Ramonville-Saint-Agne, France
  • 3Faculdade de Ciências, Universidade do Porto, 4169-007, Porto, Portugal
  • 4Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), 4450-208 Matosinhos, Portugal
  • 5Deutsches Geodätisches Forschungsinstitut, Technische Universität München, 80333 Munich, Germany
  • 6Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Telegrafenberg 14473 Potsdam, Germany
  • 7isardSAT, 08042 Barcelona, Spain
  • 8National Oceanography Centre, Southampton, SO14 3ZH, UK
  • 9DTU Space, 2800 Kongens Lyngby, Denmark
  • 10CGI, Leatherhead, KT22 7LP, UK
  • 11LEGOS, 31400 Toulouse, France
  • 12ISSI, 3912 Bern, Switzerland
  • 13ESA/ESRIN, 00044 Frascati, Italy

Abstract. Sea level is an essential climate variable (ECV) that has a direct effect on many people through inundations of coastal areas, and it is also a clear indicator of climate changes due to external forcing factors and internal climate variability. Regional patterns of sea level change inform us on ocean circulation variations in response to natural climate modes such as El Niño and the Pacific Decadal Oscillation, and anthropogenic forcing. Comparing numerical climate models to a consistent set of observations enables us to assess the performance of these models and help us to understand and predict these phenomena, and thereby alleviate some of the environmental conditions associated with them. All such studies rely on the existence of long-term consistent high-accuracy datasets of sea level. The Climate Change Initiative (CCI) of the European Space Agency was established in 2010 to provide improved time series of some ECVs, including sea level, with the purpose of providing such data openly to all to enable the widest possible utilisation of such data. Now in its second phase, the Sea Level CCI project (SL_cci) merges data from nine different altimeter missions in a clear, consistent and well-documented manner, selecting the most appropriate satellite orbits and geophysical corrections in order to further reduce the error budget. This paper summarises the corrections required, the provenance of corrections and the evaluation of options that have been adopted for the recently released v2.0 dataset ( This information enables scientists and other users to clearly understand which corrections have been applied and their effects on the sea level dataset. The overall result of these changes is that the rate of rise of global mean sea level (GMSL) still equates to ∼ 3.2 mm yr−1 during 1992–2015, but there is now greater confidence in this result as the errors associated with several of the corrections have been reduced. Compared with v1.1 of the SL_cci dataset, the new rate of change is 0.2 mm yr−1 less during 1993 to 2001 and 0.2 mm yr−1 higher during 2002 to 2014. Application of new correction models brought a reduction of altimeter crossover variances for most corrections.

Short summary
We have produced an improved monthly record of mean sea level for 1993–2015. It is developed by careful processing of the records from nine satellite altimeter missions, making use of the best available orbits, instrumental corrections and geophysical corrections. This paper details the selection process and the processing method. The data are suitable for investigation of sea level changes at scales from seasonal to long-term sea level rise, including interannual variations due to El Niño.