Antarctic Ice Sheet Monitoring

Antarctic Ice Sheet Monitoring

The Challenge

Under climate change, the AIS experiences mass balance loss, but with large uncertainty. Moreover, several key products related to AIS mass balance are lacked, such as high-accuracy elevation change data and nearshore bathymetry of the Antarctic, which is covered by ice shelves.

The Solution

In view of the increasing number of satellite and airborne observations in Antarctica and the increasing demand for ground validation, this initiative integrates large-scale, long-term satellite observations, high-precision ice surface monitoring data, and airborne geophysical observations of Antarctica and its surroundings to build a comprehensive observation system for the AIS and surrounding oceans. The initiative will develop new algorithms to reduce the uncertainty in mass balance estimation of AIS. The products will include Mass Balance Estimation, Seafloor Topography Estimation from Airborne Gravity and Real-time Monitoring of Ice Surface Elevation.

Our Impact

The outputs of this initiative help improve the accuracy of mass balance and provide key products on AIS, benefiting natural disaster mitigation, climate protection, environment, and biodiversity around Antarctica.

Policy Drivers

This project will help oceanographers and glaciologists to more accurately analyze and predict the mass balance of the Antarctic ice sheet and its impact on global sea level rise. It will also help countries and governments in coastal regions to conduct risk assessment and provide scientific decision-making basis for the international community to take adaptation actions against global environmental changes. This project also aims to improve the scientificity and efficiency of earthquake prevention and disaster reduction, climate environment and biodiversity protection, and infrastructure construction and development in coastal and sea-related areas.

How We Work

To derive the high-accuracy mass balance products, the team will focus on three parts:

1. Mass Balance Estimation

The mass balance is estimated using satellite altimetry and the input-output method. The altimetry method calculates the mass balance of AIS by measuring elevation changes over the entire ice sheet and converts them into mass changes through assumed density. The input-output method calculates the mass balance of AIS by comparing accumulation of snowfall over the interior basins with ice discharge by glaciers across the grounding line. The corresponding value of the sea level rise change caused by the ice-mass change is estimated by the mass loss of the AIS divided by the global ocean area and the density of water, based on the assumption that the mass change of the AIS is totally transformed into the equivalent mass change of water.

2. Seafloor Topography Estimation from Airborne Gravity

The measured gravity anomalies at flight altitude integrate the gravitational effects of the density difference between the seafloor topography and the overlying water and/or ice layers, the density variations within the shallow subsurface, and the regional isostatic compensation at the Mohorovicic discontinuity. The latter two effects are not due to the seafloor topography and should be removed prior to the inversion. We assume a uniform bedrock density, remove the gravitational effect of the ice layer and the regional gravity field from the measured gravity anomalies, and use the remaining gravity anomaly to estimate the seafloor topography through the simulated annealing method by minimizing the difference between the remaining and the forward-computed gravity anomalies.

3. Real-time Monitoring of Ice Surface Elevation and its change

The terrestrial monitoring platform consists of several sensors: laser rangers, cameras, corner cube retroreflectors, and meteorological devices. First, the coordinates of the reference GNSS antenna at Zhongshan station are precisely calculated. Then, the GNSS observations at both Zhongshan station and the ice surface are combined to derive the baseline differences. All GNSS observations are sent back to a server through Beidou/Iridium Satellite/Argo. After postprocessing, the real-time ice surface elevations and ice-flow velocities are obtained.


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