Greenland_Ice_Sheet_cci+ Reference: ST-DTU-ESA-GISCCI+-ATBD-001 Algorithm Theoretical Basis Document Version : 1.1 page (ATBD) for CCI+ Phase 1 Date : 05 May 2020 1/43 ESA Climate Change Initiative (CCI+) Essential Climate Variable (ECV) Greenland_Ice_Sheet_cci+ (GIS_cci+) Algorithm Theoretical Basis Document (ATBD) for CCI+ Phase 1 Prime & Science Lead: René Forsberg DTU Space, Copenhagen, Denmark [email protected] Technical Officer: Marcus Engdahl ESA ESRIN, Frascati, Italy [email protected] Consortium: Asiaq Greenland Survey (ASIAQ) DTU-Space, Department of Geodynamics (DTU-S) DTU-Space, Department of Microwaves and Remote Sensing (DTU-N) Danish Meteorological Institute (DMI) Environmental Earth Observation IT GmbH (ENVEO) Science [&] Technology AS (S&T) Technische Universität Dresden (TUDr) The Geological Survey of Denmark and Greenland (GEUS) The Niels Bohr Institute (NBI) University of Leeds, School of Earth and Environment (UL) Greenland_Ice_Sheet_cci+ Reference: ST-DTU-ESA-GISCCI+-ATBD-001 Algorithm Theoretical Basis Document Version : 1.1 page (ATBD) for CCI+ Phase 1 Date : 05 May 2020 2/43 Signatures page Prepared by Jan Wuite Lead Author, ENVEO Date: 19 Feb. 2020 Issued by Daniele Fantin, Project Manager, S[&]T Date: 5 May 2020 Checked by Rene Forsberg Science Leader, DTU-S Date: 5 May 2020 Approved Marcus Engdahl Date: by ESA Technical Officer Greenland_Ice_Sheet_cci+ Reference: ST-DTU-ESA-GISCCI+-ATBD-001 Algorithm Theoretical Basis Document Version : 1.1 page (ATBD) for CCI+ Phase 1 Date : 05 May 2020 3/43 Table of Contents Change Log ........................................................................................................... 5 Acronyms and Abbreviations ................................................................................ 6 1 Introduction ................................................................................................... 8 1.1 Purpose and Scope ......................................................................................... 8 1.2 Document Structure ....................................................................................... 8 1.3 Applicable and Reference Documents ................................................................ 8 2 Surface Elevation Change ............................................................................... 9 2.1 Introduction .................................................................................................. 9 2.2 Review of scientific background ........................................................................ 9 2.3 Algorithms ..................................................................................................... 9 2.4 Input data and algorithm output .................................................................... 10 2.4.1 Input data ............................................................................................................11 2.4.2 Algorithm Output ..................................................................................................12 2.5 Accuracy and performance ............................................................................ 13 2.6 Capabilities and known limitations .................................................................. 13 2.7 References .................................................................................................. 13 3 Ice Velocity (SAR) ........................................................................................ 15 3.1 Introduction ................................................................................................ 15 3.2 Review of scientific background ...................................................................... 15 3.3 Algorithms ................................................................................................... 15 3.3.1 Differential SAR Interferometry ...............................................................................15 3.3.2 Processing ............................................................................................................16 3.3.3 Remarks ..............................................................................................................18 3.4 Input data and algorithm output .................................................................... 19 3.4.1 Input Data ...........................................................................................................19 3.4.2 Algorithm output ...................................................................................................19 3.5 Accuracy and performance ............................................................................ 19 3.6 Capabilities and known limitations .................................................................. 21 3.7 References .................................................................................................. 21 4 Ice Velocity (Optical) ................................................................................... 22 4.1 Introduction ................................................................................................ 22 4.2 Review of scientific background ...................................................................... 22 4.3 Algorithm .................................................................................................... 22 4.4 Input data and algorithm output .................................................................... 23 4.5 Accuracy and performance ............................................................................ 24 4.6 Capabilities and known limitations .................................................................. 25 4.7 References .................................................................................................. 25 5 Gravimetric Mass Balance............................................................................. 26 5.1 Introduction ................................................................................................ 26 5.1 Scientific background update ......................................................................... 26 5.2 Algorithms ................................................................................................... 28 5.3 Input data and algorithm output .................................................................... 29 5.4 Capabilities and known limitations .................................................................. 29 Greenland_Ice_Sheet_cci+ Reference: ST-DTU-ESA-GISCCI+-ATBD-001 Algorithm Theoretical Basis Document Version : 1.1 page (ATBD) for CCI+ Phase 1 Date : 05 May 2020 4/43 5.5 References .................................................................................................. 29 6 Mass Flow Rate and Ice Discharge ............................................................... 31 6.1 Introduction ................................................................................................ 31 6.2 Review of scientific background ...................................................................... 31 6.3 Algorithms ................................................................................................... 32 6.3.1 Terminology .........................................................................................................32 6.3.2 Gate location ........................................................................................................32 6.3.3 Thickness .............................................................................................................33 6.3.4 Missing or invalid data ...........................................................................................33 6.3.5 Discharge .............................................................................................................33 6.4 Input data and algorithm output .................................................................... 33 6.4.1 Input Data ...........................................................................................................33 6.4.2 Algorithm Output ..................................................................................................34 6.5 Accuracy and performance ............................................................................ 34 6.5.1 Accuracy ..............................................................................................................34 6.5.2 Performance .........................................................................................................36 6.6 Capabilities and known limitations .................................................................. 36 6.7 References .................................................................................................. 37 7 Supraglacial Lake ......................................................................................... 40 7.1 Introduction ................................................................................................ 40 7.2 Review of scientific background ...................................................................... 40 7.3 Algorithms ................................................................................................... 40 7.4 Input data and algorithm output .................................................................... 41 7.5 Accuracy and performance ............................................................................ 41 7.6 Capabilities and known limitations .................................................................. 42 7.7 References