A monthly 5 km Arctic sea ice thickness product from 1995 to 2025 using multiple radar altimetry data

Arctic sea ice is of great importance to the regional and global climate change study. Satellite observations have demonstrated that the Arctic sea ice extent has been declined for the last four decades. However, long-term variations of the Arctic sea ice thickness (SIT) are less focused as SIT cannot be measured directly by satellite-based instruments. Here, we presented a monthly Arctic SIT product based on multiple radar altimetry observations from ERS-2, Envisat, and CryoSat-2. To ensure the accuracy of the SIT retrievals, we proposed a novel data processing procedure including leads detection, freeboard conversion to thickness and inter-mission bias correction. Finally, we were able to generate the monthly SIT estimates for the Arctic Ocean from October 1995 to April 2025. The thickness estimates are posted on a 5 km resolution polar stereographic grid. The variations of the Arctic SIT are analyzed in terms of the spatial and temporal distributions. We also compared our SIT estimates with observations from upward looking sonars (ULSs) and airborne laser altimetry from Operation IceBridge (OIB), as well as seven publicly released Arctic SIT products. The validation results demonstrate that our SIT product features equivalent accuracy with existing products. The accuracy of our products is about 0.4 m during Envisat period, and is within 0.2 m during CryoSat-2 period.北极海冰对区域及全球气候变化研究具有重要意义。卫星观测数据显示，过去四十年来北极海冰范围持续缩减。然而，由于北极海冰厚度（Sea Ice Thickness, SIT）无法通过星载仪器直接测量，其长期变化特征尚未得到足够关注。本研究基于ERS-2、Envisat及CryoSat-2多颗卫星的雷达测高观测数据，构建了北极海冰厚度的逐月产品。为保障海冰厚度反演的精度，本研究提出了一套全新的数据处理流程，涵盖冰间水道检测、海冰干舷转换为海冰厚度以及跨任务偏差校正等环节。最终，本研究生成了1995年10月至2025年4月期间北冰洋的逐月海冰厚度估算数据。该厚度估算数据以5公里分辨率的极射赤平投影格网形式发布。本研究从时空分布维度对北极海冰厚度的变化特征展开分析，并将自研的海冰厚度估算数据与向上观测声纳（Upward Looking Sonars, ULSs）的观测数据、冰桥行动（Operation IceBridge, OIB）的机载激光测高数据，以及7套已公开的北极海冰厚度产品进行了对比。验证结果表明，本研究的海冰厚度产品与现有同类产品的精度相当。在Envisat卫星任务期间，本产品的精度约为0.4米；在CryoSat-2卫星任务期间，精度则控制在0.2米以内。