ESA / ECSAT CCIWV.REP.022 Water Vapour Climate Change Initiative (WV_cci) - CCI+ Phase 2 D2.2 Project : Water Vapour Climate Change Initiative (WV_cci) - CCI+ Phase 2 Document Title: ATBD Part 3 - Merged CDR-3 and CDR-4 products Reference : D2.2 Issued : 27 June 2023 Issue : 3.0 Client : ESA / ECSAT Author(s) : Michaela Hegglin and Hao Ye (UoR) Copyright : Water_Vapour_cci Consortium and ESA iii