Reconstructing Long-Term Arctic Sea Ice Freeboard, Thickness, and Volume Changes from Envisat, CryoSat-2, and ICESat-2

The rapid decline of Arctic sea ice (ASI) has significantly impacted the global climate, polar ecosystems, and shipping courses. Precise long-term and high-resolution changes in ASI estimates are crucial for adapting to climate change and developing Arctic marine resources. Satellite altimeters have been applied to detect ASI for several decades. However, the mission periods of various altimetry satellites are limited, making it challenging to estimate the long-term change process of ASI thickness from the observations of a single altimetry satellite or simply combining multi-source satellite altimetry data. The purpose of this study is to comprehensively obtain continuous long-term ASI freeboard, thickness, and volume characteristics using the gridded nadirization method from Envisat, CryoSat-2, and ICESat-2 altimeter data. The relationship between surface temperature and surface wind field is also investigated. The freeboard, thickness, extent, and area of ASI consistently showed loss trends during 2002-2021, and sea ice volume decreased by 5437 km3/month. Sea surface temperature and sea surface wind field are two of the essential influencing factors on ASI variations. This study will assist in clarifying the relationship between climate variations and the ASI decline. Abstract: Satellite altimeters have been used to monitor Arctic sea ice (ASI) thickness for several decades, but whether the different altimeter missions (such as radar and laser altimeters) are in agreement with each other and suitable for long-term research needs to be investigated. To analyze the spatiotemporal characteristics of ASI, continuous long-term first-year ice, and multi-year ice of ASI freeboard, thickness, and volume from 2002 to 2021 using the gridded nadirization method from Envisat, CryoSat-2, and ICESat-2, altimeter data are comprehensively constructed and assessed. The influences of sea surface temperature (SST) and sea surface wind field (SSW) on ASI are also discussed. The freeboard/thickness and extent/area of ASI all varied seasonally and reached their maximum and minimum in April and October, March and September, respectively. From 2002 to 2021, the freeboard, thickness, extent, and area of ASI all consistently showed downward trends, and sea ice volume decreased by 5437 km(3)/month. SST in the Arctic rose by 0.003 degrees C/month, and the sea ice changes lagged behind this temperature variation by one month between 2002 and 2021. The meridional winds blowing from the central Arctic region along the eastern coast of Greenland to the North Atlantic each month are consistent with changes in the freeboard and thickness of ASI. SST and SSW are two of the most critical factors driving sea ice changes. This study provides new data and technical support for monitoring ASI and exploring its response mechanisms to climate change.

Automated summary

The rapid decline of Arctic sea ice has had significant impacts on the global climate, polar ecosystems, and shipping routes. Precise long-term and high-resolution estimates of Arctic sea ice changes are crucial for adapting to climate change and developing Arctic marine resources. This study comprehensively analyzes the characteristics of Arctic sea ice thickness, volume, and extent using satellite altimeter data and investigates the relationship between surface temperature and wind field. The results show consistent loss trends in Arctic sea ice freeboard, thickness, extent, and area, with a significant decrease in sea ice volume. Sea surface temperature and wind field are identified as important influencing factors on Arctic sea ice variations.