Abstract Surface mass balance (SMB) provides mass input to the surface of the Antarctic and Greenland Ice Sheets and therefore comprises an important control on ice sheet mass balance and resulting contribution to global sea level change. As ice sheet SMB varies highly across multiple scales of space (meters to hundreds of kilometers) and time (hourly to decadal), it is notoriously challenging to observe and represent in models. In addition, SMB consists of multiple components, all of which depend on complex interactions between the atmosphere and the snow/ice surface, large‐scale atmospheric circulation and ocean conditions, and ice sheet topography. In this review, we present the state‐of‐the‐art knowledge and recent advances in ice sheet SMB observations and models, highlight current shortcomings, and propose future directions. Novel observational methods allow mapping SMB across larger areas, longer time periods, and/or at very high (subdaily) temporal frequency. As a recent observational breakthrough, cosmic ray counters provide direct estimates of SMB, circumventing the need for accurate snow density observations upon which many other techniques rely. Regional atmospheric climate models have drastically improved their simulation of ice sheet SMB in the last decade, thanks to the inclusion or improved representation of essential processes (e.g., clouds, blowing snow, and snow albedo), and by enhancing horizontal resolution (5–30 km). Future modeling efforts are required in improving Earth system models to match regional atmospheric climate model performance in simulating ice sheet SMB, and in reinforcing the efforts in developing statistical and dynamic downscaling to represent smaller‐scale SMB processes.

中文翻译：

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冰盖表面质量平衡的观测和模拟

摘要 表面质量平衡（SMB）为南极和格陵兰冰盖表面提供质量输入，因此对冰盖质量平衡及其对全球海平面变化的影响具有重要的控制作用。由于冰盖 SMB 在空间（米到数百公里）和时间（每小时到十年）的多个尺度上变化很大，因此在模型中观察和表示非常具有挑战性。此外，SMB由多个组成部分组成，所有这些组成部分都取决于大气与雪/冰表面之间复杂的相互作用、大范围的大气环流和海洋条件以及冰盖地形。在这篇综述中，我们介绍了冰盖 SMB 观测和模型的最新知识和最新进展，强调了当前的缺点，并提出了未来的方向。新颖的观测方法允许在更大的区域、更长的时间段和/或以非常高的（亚日）时间频率绘制 SMB。作为最近的一项观测突破，宇宙射线计数器可以直接估计 SMB，从而避免了许多其他技术所依赖的精确雪密度观测的需要。区域大气气候模型在过去十年中极大地改进了对冰盖 SMB 的模拟，这要归功于基本过程（例如云、吹雪和雪反照率）的包含或改进的表示，以及通过提高水平分辨率（5-30公里）。未来的建模工作需要改进地球系统模型，以匹配模拟冰盖 SMB 的区域大气气候模型性能，并加强开发统计和动态缩小尺度的努力，以代表较小规模的 SMB 过程。