ESA Sea State Climate Change Initiative (Sea_State_cci) : Global remote sensing merged multi-mission monthly gridded significant wave height, L4 product, version 1.1

The ESA Sea State Climate Change Initiative (CCI) project has produced global merged multi-sensor time-series of monthly gridded satellite altimeter significant wave height (referred to as Level 4 (L4) data) with a particular focus for use in climate studies. This dataset contains the Version 1.1 Remote Sensing Sea Surface Height product, gridded over a global regular cylindrical projection (1°x1° resolution), averaging valid and good measurements from all available altimeters on a monthly basis (using the L2P products also available). These L4 products are meant for statistics and visualization. This first version of the Sea State CCI products is inherited from the GlobWave project, building on experience and existing outputs. It extends and improves the GlobWave products ,which were a post-processing over existing L2 altimeter agency products with additional filtering, corrections and variables. A major improvement consists in a new denoised sea surface height variable using Empirical Mode Decomposition, which was used as input to these monthly statistical fields. The altimeter data used in the Sea State CCI dataset v1.1 come from multiple satellite missions spanning from 1991 to 2018 (ERS-1, ERS-2, Topex, Envisat, GFO, CryoSat-2, Jason-1, Jason-2, Jason-3, SARAL). Many altimeters are bi-frequency (Ku-C or Ku-S) and only measurements in Ku band were used, for consistency reasons, being available on each altimeter but SARAL (Ka band).

欧洲空间局（European Space Agency）海态气候变化倡议（Sea State Climate Change Initiative, CCI）项目已生成全球多传感器融合逐月网格化卫星测高有效波高时间序列（即第四级（Level 4, L4）数据），该数据集专门面向气候研究应用。本数据集包含V1.1版本遥感海面高度产品，采用全球规则圆柱投影（1°×1°分辨率）进行网格化处理，基于所有可用测高卫星的有效优质观测数据，并结合同期可用的L2P产品按月进行平均计算。该类L4产品主要用于统计分析与可视化展示。海态CCI产品的首个版本源自GlobWave项目，继承了该项目的研究经验与已有产出，并对其进行了扩展与优化。原GlobWave产品是对现有L2级测高卫星机构产品开展后处理得到的，新增了滤波、校正及变量模块。本次优化的核心改进之一是采用经验模态分解（Empirical Mode Decomposition）生成的去噪海面高度新变量，该变量被用作本次逐月统计场的输入数据。海态CCI数据集v1.1所使用的测高数据来自1991年至2018年期间的多颗卫星任务，包括ERS-1、ERS-2、Topex、Envisat、GFO、CryoSat-2、Jason-1、Jason-2、Jason-3及SARAL。多数测高卫星为双频载荷（覆盖Ku-C或Ku-S波段），出于数据一致性考虑，仅使用Ku波段的观测数据，仅SARAL例外，其搭载的是Ka波段载荷。