An Accurate and Homogeneous Altimeter Sea Level Record from the ESA Climate Change Initiative

Sea Level is a very sensitive index of climate change since it integrates the impacts of ocean warming and ice mass loss from 25 glaciers and the ice sheets. Sea Level has been listed as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS). During the past 25 years, the sea level ECV has been measured from space by different altimetry missions that have provided global and regional observations of sea level variations. As part of the Climate Change Initiative (CCI) program of the European Space Agency (ESA) (established in 2010), the Sea Level project (SL_cci) aimed at providing an accurate and homogeneous long-term satellite-based sea level record. At the end of the first phase of the 30 project (2010-2013), an initial version (v1.1) of the sea level ECV has been made available to users (Ablain et al., 2015). During the second phase (2014-2017), improved altimeter standards have been selected to produce new sea level products (called SL_cci v2.0) based on 9 altimeter missions for the period 1993-2015 (https://doi.org/10.5270/esa-sea_level_cci1993_2015-v_2.0-201612). Corresponding orbit solutions, geophysical corrections and altimeter standards used in this v2.0 dataset are described in details in Quartly et al. (2017). The present paper focuses on the description of the SL_cci v2.0 ECV 35 and associated uncertainty and discusses how it has been validated. Various approaches have been used for the quality assessment such as internal validation, comparisons with sea level records from other groups and with in-situ measurements, Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2017-116 O pe n A cc es s Earth System Science Data D icu ssio n s Manuscript under review for journal Earth Syst. Sci. Data Discussion started: 17 October 2017 c © Author(s) 2017. CC BY 4.0 License.

[1]  Armin Köhl,et al.  Evaluation of the GECCO2 ocean synthesis: transports of volume, heat and freshwater in the Atlantic , 2015 .

[2]  Byron D. Tapley,et al.  Seasonal global water mass budget and mean sea level variations , 1998 .

[3]  A. Cazenave,et al.  Spatial trend patterns in the Pacific Ocean sea level during the altimetry era: the contribution of thermocline depth change and internal climate variability , 2015, Ocean Dynamics.

[4]  K. Taylor.  Summarizing multiple aspects of model performance in a single diagram , 2001 .

[5]  S. Griffies,et al.  Ocean Modeling and Data Assimilation in the Context of Satellite Altimetry , 2017 .

[6]  M. Balmaseda,et al.  The new eddy-permitting ORAP5 ocean reanalysis: description, evaluation and uncertainties in climate signals , 2017, Climate Dynamics.

[7]  M. Balmaseda,et al.  736 The ECMWF-MyOcean 2 eddy-permitting ocean and sea-ice reanalysis ORAP 5 . Part 1 : Implementation , 2015 .

[8]  Frank J. Wentz,et al.  SSM/I Version-7 Calibration Report , 2012 .

[9]  Sergei Rudenko,et al.  Improvements in Precise Orbits of Altimetry Satellites and Their Impact on Mean Sea Level Monitoring , 2017, IEEE Transactions on Geoscience and Remote Sensing.

[10]  A. Cazenave,et al.  Satellite Altimetry-Based Sea Level at Global and Regional Scales , 2016, Surveys in Geophysics.

[11]  David W. Hancock,et al.  On the "Cal-Mode" Correction to TOPEX Satellite Altimetry and Its Effect on the Global Mean Sea Level Time Series , 2017 .

[12]  Sergei Rudenko,et al.  A new phase in the production of quality-controlled sea level data , 2017 .

[13]  Testing the Quality of Sea-Level Data Using the GECCO Adjoint Assimilation Approach , 2016, Surveys in Geophysics.

[14]  G. Meehl,et al.  Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes , 2016, Surveys in Geophysics.

[15]  Anny Cazenave,et al.  Tropical Pacific spatial trend patterns in observed sea level: internal variability and/or anthropogenic signature? , 2012 .

[16]  Chen Zhao-hui.  Impacts of Seasonal Fossil and Ocean Emissions on the Seasonal Cycle of Atmospheric CO2 , 2011 .

[17]  Anny Cazenave,et al.  The rate of sea-level rise , 2014 .

[18]  Sergei Rudenko,et al.  Improved Sea Level record over the satellite altimetry era (1993-2010) from the Climate Change Initiative project , 2015 .

[19]  M. England,et al.  Constraining Wind Stress Products with Sea Surface Height Observations and Implications for Pacific Ocean Sea Level Trend Attribution , 2012 .

[20]  Clara Lázaro,et al.  Improved wet path delays for all ESA and reference altimetric missions , 2015 .

[21]  Ole Baltazar Andersen,et al.  ALES+: Adapting a homogenous ocean retracker for satellite altimetry to sea ice leads, coastal and inland waters , 2018, Remote Sensing of Environment.

[22]  Duncan J. Wingham,et al.  Western Arctic Ocean freshwater storage increased by wind-driven spin-up of the Beaufort Gyre , 2012 .

[23]  Matt A. King,et al.  Unabated global mean sea-level rise over the satellite altimeter era , 2015 .

[24]  Sergei Rudenko,et al.  Influence of time variable geopotential models on precise orbits of altimetry satellites, global and regional mean sea level trends , 2014 .

[25]  S. Desai,et al.  Revisiting the pole tide for and from satellite altimetry , 2015, Journal of Geodesy.

[26]  S. Somot,et al.  A fully coupled Mediterranean regional climate system model: design and evaluation of the ocean component for the 1980–2012 period , 2014 .

[27]  Shannon T. Brown.  A Novel Near-Land Radiometer Wet Path-Delay Retrieval Algorithm: Application to the Jason-2/OSTM Advanced Microwave Radiometer , 2010, IEEE Transactions on Geoscience and Remote Sensing.