罗斯冰架、菲尔希纳-龙尼冰架和埃默里冰架是南极的三大冰架,对南极冰盖有着重要的支撑作用.然而,目前三大冰架稳定性的研究多集中在一种或几种因素,缺少多参数的综合评估.为实现南极三大冰架不稳定性和长时序变化趋势系统的分析,本文综合统计、分析了三大冰架的关键参数变化,包括三大冰架的表面高程、底部融化、表面融水、关键裂缝、缝合区、前缘线、接地线、冰流速以及物质平衡变化.此外,本文选取了南极已经崩塌的拉森B冰架、处在快速变化且已发生结构性变化的松岛冰架和处于加速状态的托滕冰架作为参考冰架,将三大冰架与参考冰架对应的关键参数进行对比分析,最终确定南极三大冰架的变化状态和稳定性趋势.研究结果表明,三大冰架的多项关键参数与参考冰架相比均变化较小,有50%的参数小于加速变化状态的托滕冰架,有88%的参数小于快速变化状态的松岛冰架,有100%的参数小于崩塌状态的拉森B冰架;并且对未小于托滕冰架的参数具体分析后,发现其符合三大冰架稳定状态的情况.因此,目前三大冰架处于稳定的自然变化状态,短期内不会发生剧烈的结构性变化.但在全球气候变暖的情形下,该变化趋势存在较大的不确定性,需长期进行追踪观测从而评估其对全球海平面上升的影响.

Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) carries a photon-counting laser altimeter with an unprecedented elevation accuracy of 2-4 cm. Since its data availability in 2018, there has been a challenge for the establishment of a new data processing model that can take advantage of this satellite for accurately estimating volumetric changes in Antarctica and associated contribution to global sea level rise (GSLR). We introduce an innovative multitemporal elevation change estimation model (MECEM) that separates precipitation effects from topographic influences to eliminate their correlations and estimates the elevation change rates effectively through a spatiotemporal iterative procedure. The MECEM results are validated by using GNSS in situ observations, snow stakes measurements, and airborne altimetric survey data. The results are also compared with those from ICESat and ESA multimission radar altimetric dataset. It is demonstrated that the model is capable of estimating small thickening of 1.8 +/- 0.1 cm yr(-1) in the Vostok subglacial lake region. Using ICESat-2 ATL06 data from 2019 to 2023, the model is proven to be effective in the estimation of elevation change rates in Antarctic basins of different characteristics. Our results show that an increase of 0.103 +/- 0.001 m yr(-1) in thickening is found from 2017-2021 to 2019-2023 in Dronning Maud Land. Furthermore, an accelerated thinning by -0.12 +/- 0.035 m yr(-1) is witnessed from 2003-2019 to 2019-2023 in the fast-flowing Pine Island Glacial. With more ICESat-2 data acquired, the developed MECEM model can be applied for estimating the contribution of the entire Antarctic ice sheet (AIS) to GSLR.

The Antarctic Ice Sheet (AIS) has been losing ice mass and contributing to global sea level rise (GSLR). Given its mass that is enough to cause ∼58 m of GSLR, accurate estimation of mass balance trend is critical for AIS mass loss monitoring and sea level rise forecasting. Here, we present an improved approach to reconciled solutions of mass balance in AIS and its regions from multiple contributing solutions using the input-out, altimetric, and gravimetric methods. In comparison to previous methods, such as IMBIE 2018, this approach utilizes an adaptive data aggregation window to handle the heterogeneity of the contributing solutions, including the number of solutions, temporal distributions, uncertainties, and estimation techniques. We improved the regression-based method by using a two-step procedure that establishes ensembled solutions within each method (input-output, altimetry, or gravimetry) and then estimates the method-independent reconciled solutions. For the first time, 16 contributing solutions from 8 Chinese institutions are used to estimate the reconciled mass balance of AIS and its regions from 1996 to 2021. Our results show that AIS has lost a total ice mass of ∼3213±253 Gt during the period, an equivalent of ∼8.9±0.7 mm of GSLR. There is a sustained mass loss acceleration since 2006, from 88.1±3.6 Gt yr−1 during 1996–2005 to 130.7±8.4 Gt yr−1 during 2006–2013 and further to 157.0±9.0 Gt yr−1 during 2014–2021. The mass loss signal in the West Antarctica and Antarctic Peninsula is dominant and clearly presented in the reconciled estimation and contributing solutions, regardless of estimation methods used and fluctuation of surface mass balance. Uncertainty and challenges remain in mass balance estimation in East Antarctica. This reconciled estimation approach can be extended and applied for improved mass balance estimation in the Greenland Ice Sheet and mountain glacier regions.

Elevation changes are crucial input data for mass balance assessment based on satellite altimetry. However, due to the accuracy limitations of altimetry data and mass conversion models, a significant uncertainty remains in estimating the mass balance of the Antarctic ice sheet, especially in East Antarctica. The ICESat-2 photon altimetry satellite enhances the precision of ice sheet surface elevation measurements to an accuracy of 2-4 cm. This improvement is particularly beneficial for detecting subtle elevation changes in East Antarctica. The ATL11 product from ICESat-2 offers a time series of ice surface elevations across Antarctica, enabling direct calculation of elevation change rates. To evaluate the capability of the ATL11 product in accurately depicting detailed elevation changes within the local terrain, we selected the Vostok Subglacial Lake as the validation region. Our research involves comparing fitted surface elevation change rates with in-situ data, while also considering surface mass balance, wind, and surface elevation to analyze the factors contributing to small differences in elevation changes within the local lake area. This analysis aims to identify the factors contributing to the minor variations in elevation changes within the local lake area. According to our analysis, the Vostok Lake surface elevation change rate is 2.00 +/- 0.77 cm yr-1 from April 2019 to June 2023, with an average period of 356 +/- 81 days. The results demonstrate that the ATL11 elevation product sequence has the potential to accurately characterize subtle elevation changes and seasonal variations in the Antarctic ice sheet.

The Ross, Filchner-Ronne, and Amery ice shelves are the three largest ice shelves in Antarctica, playing a crucial role in supporting the Antarctic ice sheet. However, current studies on the stability of the three largest ice shelves primarily focus on singular or limited factors, lacking a comprehensive assessment of multiple parameters. To systematically and in-depth study the stability and trend of the three largest ice shelves, we comprehensively collected and analyzed key parameters, including elevation changes, basal melting, surface meltwater, major rifts propagation rate, suture zones, ice front area change rate, grounding lines, ice velocity, and mass balance. Additionally, we selected the collapsed Larsen B Ice Shelf (LBIS), the rapidly changing and structurally weakened Pine Island Ice Shelf (PIIS), and the accelerating Totten Ice Shelf (TIS) as reference ice shelves. By comparing and analyzing the key parameters between these reference ice shelves and the three largest ice shelves, we find the status and trends in the stability of the latter. Our findings reveal that most key parameters of the three largest ice shelves present relatively minor variations compared to those of the reference ice shelves. Specifically, 50% of the parameters are smaller than those of the accelerating TIS, 88% are smaller than those of the rapidly changing PIIS, and all parameters are smaller than those of the collapsed LBIS. Furthermore, after analyzing parameters that are not smaller than those of the TIS, it is observed that they remain in a stable state. Hence, the three largest ice shelves are currently undergoing natural changes that do not threaten their stability in the short term. Nevertheless, the evolution of the ice shelves under global climate change remains uncertain, making long-term observation and monitoring essential to assess their impact on sea level rise.

The Antarctic Ice Sheet's mass balance has a significant impact on global sea level change. Improving the precision of mass balance estimation over the entire Antarctic Ice Sheet is critical for predicting global sea level rise. The advancement of satellite technology, particularly polar observation satellites, will help us understand and protect the ice sheet. Studying the Antarctic Ice Sheet's response to the global climate change and its feedback mechanism is also critical for increasing the scientific understanding of Antarctica. This review paper summarizes the development of various Antarctic monitoring satellites as well as remote sensing data products that are currently available. At the same time, it discusses techniques for satellite monitoring and estimation methods for mass balance in Antarctica. Finally, recommendations for satellite observation techniques and methodology development are provided to improve the capability of long-term monitoring and prediction of ice sheet changes.

Ice velocity is a direct and essential indicator of the stability of Antarctic ice sheet in response to global climate change. It is also one of the crucial data to accurately estimate the contribution of the Antarctic ice sheet to global sea level rise. Optical remote sensing imagery is an important data source for large-scale extraction of Antarctic ice velocity because of the advantages of data acquisition in fine temporal and spatial resolution. In this paper, we review the existing methods of Antarctic ice velocity reconstruction by using optical images, introduce relevant software and tools, and summarize Antarctic ice velocity products generated based on optical remote sensing images from 1960s to present. Furthermore, we demonstrate applications of the ice velocity products in some typical areas, such as mass balance evaluation, long time series changes monitoring of ice shelves, etc. Finally, the advantages and future development trends of optical remote sensing images for Antarctic ice velocity reconstruction are summarized.

High accuracy reconstruction of historical ice flow velocity fields is crucial in mass balance research of the Antarctic Ice Sheet by utilizing the input-output approach. A historical flow velocity of the Western Pacific Ocean sector region of East Antarctica from 1963 to 1989 was mapped and then corrected for its velocity overestimation. In this study, we analyzed the spatial distribution of the corrected values, and further assessed the relationship between the corrected values and related factors including timespan of image pairs, ice flow velocity, the spatial acceleration of ice flow velocity, and surface slope. The results indicate that the corrected ice flow velocity points are mostly dispersed between a buffer 25 km upstream and a buffer 25 km downstream the grounding line, with the largest mean value emerging in the region between the grounding line and its 25 km downstream. The corrected values exhibit linear correlation with three conditions: 1) when the ice flow velocity range is 0 – 1586 m/y, 2) spatial acceleration is 0 – 69 (m/y)/km, and 3) the slope is 0 – 1.95 degrees and the R2 is higher than 0.7. However, the correlation between timespan and corrected values is not obvious. The corrected values for the floating region have a greater linear correlation with all three factors than the inland region. Ice flow velocity, spatial acceleration, and surface slope all have an influence on the distribution of the corrected values of the reconstructed historical ice flow velocity maps, and may further affect the assessment of the mass balance of the Antarctic Ice Sheet.