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, Sergei Rudenko4,5, Loren Carrère2, Pablo Nilo García6, Paolo Cipollini7, Ole Baltazar Andersen8, Jean-Christophe Poisson2, Sabrina Mbajon Njiche9, Anny Cazenave10,11, and Jérôme Benveniste121Plymouth Marine Laboratory, Plymouth, PL1 3DH, United Kingdom 2CLS, 31520 Ramonville-Saint-Agne, France 3University of Porto, 4099-002 Porto, Portugal 4Deutsches Geodätisches Forschungsinstitut, Technische Universität München, 80333 Munich, Germany 5Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Telegrafenberg 14473 Potsdam, Germany 6sardSAT, 08042 Barcelona, Spain 7National Oceanography Centre, Southampton, SO14 3ZH, United Kingdom 8DTU Space, 2800 Kongens Lyngby, Denmark 9CGI, Leatherhead, KT22 7LP, United Kingdom 10LEGOS, 31400 Toulouse, France 11ISSI, 3912 Bern, Switzerland 12ESA/ESRIN, 00044 Frascati, Italy
Received: 27 Mar 2017 – Accepted for review: 12 Apr 2017 – Discussion started: 13 Apr 2017
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 merges data from 9 different altimeter missions in a clear and well-documented manner, selecting the most appropriate satellite orbits and geophyiscal corrections in order to 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 (DOI:10.5270/esa-sea_level_cci-1993_2015-v_2.0-201612). This information enables scientists and other users to clearly understand which corrections have been applied and their effects on the sea level dataset. However, the overall result of these changes is that the rate of rise of global mean sea level still equates to ~3.2 mm yr−1 during 1992-2015.
Quartly, G. D., Legeais, J.-F., Ablain, M., Zawadzki, L., Fernandes, M. J., Rudenko, S., Carrère, L., García, P. N., Cipollini, P., Andersen, O. B., Poisson, J.-C., Mbajon Njiche, S., Cazenave, A., and Benveniste, J.: A new phase in the production of quality-controlled sea level data, Earth Syst. Sci. Data Discuss., doi:10.5194/essd-2017-23, in review, 2017.