The Cryosphere model Comparison tool (CmCt): The Ice Sheet Model Comparison Tool for Greenland and Antarctica using various Altimetry, and GRACE Satellite Data

The Cryosphere model Comparison tool (CmCt) is a web-based ice sheet model validation tool that has been developed by NASA to facilitate direct comparison between satellite observational data and various ice sheet models. The CmCt allows the user to take advantage of several decades worth of satellite-based observations from Greenland and Antarctica. Currently, the CmCt is used to compare ice sheet models provided by the user with remotely sensed satellite ICESat (Ice, Cloud, and land Elevation Satellite) laser altimetry, ERS-1, ERS-2, and Envisat radar altimetry data, and GRACE (Gravity Recovery and Climate Experiment) satellite data. For the comparison with GRACE data, the uploaded ice sheet model can also be compared with different solutions: GRACE Mascon or spherical harmonics. The CmCt works for Greenland and Antarctica submissions. One or many models can be directly uploaded through the CmCt website and be compared with observational data, or do inter-comparisons with data from different time periods. As a result of the comparison, the CmCt calculates many different kinds of metrics including statistics on the differences between the model and observations, and other various quantitative and qualitative metrics. These metrics can be used in evaluating the different model simulations against the observations to validate whether the ice sheet model is doing a good job of representing the real world. The qualitative metrics consist of a range of visual outputs and quantitative metrics consist of several whole-ice-sheet scalar values that can be used to assign an overall score to a particular simulation. The CmCt also has a toolbox feature that provides the ice sheet modeler tools and features to easily create publication quality images from the results. Future versions of the tool will include comparisons with other models and other datasets that are of interest to the modeling community, such as ice velocity, surface mass balance and other additional or alternative metrics that are beneficial for comparing and contrasting model output and observations.