Reconstructions of past temperature and precipitation are fundamental to modeling the Greenland Ice Sheet and assessing its sensitivity to climate. Paleoclimate information is sourced from proxy records and climate-model simulations; however, the former are spatially incomplete while the latter are sensitive to model dynamics and boundary conditions. Efforts to combine these sources of information to reconstruct spatial patterns of Greenland climate over glacial–interglacial cycles have been limited by assumptions of fixed spatial patterns and a restricted use of proxy data. We avoid these limitations by using paleoclimate data assimilation to create independent reconstructions of mean-annual temperature and precipitation for the last 20 000 years. Our method uses oxygen isotope ratios of ice and accumulation rates from long ice-core records and extends this information to all locations across Greenland using spatial relationships derived from a transient climate-model simulation. Standard evaluation metrics for this method show that our results capture climate at locations without ice-core records. Our results differ from previous work in the reconstructed spatial pattern of temperature change during abrupt climate transitions; this indicates a need for additional proxy data and additional transient climate-model simulations. We investigate the relationship between precipitation and temperature, finding that it is frequency dependent and spatially variable, suggesting that thermodynamic scaling methods commonly used in ice-sheet modeling are overly simplistic. Our results demonstrate that paleoclimate data assimilation is a useful tool for reconstructing the spatial and temporal patterns of past climate on timescales relevant to ice sheets.

中文翻译：

---

使用数据同化，过去2万年来的格陵兰温度和降水

重建过去的温度和降水是格陵兰冰原建模和评估其对气候敏感性的基础。古气候信息来自代理记录和气候模式模拟。但是，前者在空间上不完整，而后者对模型动力学和边界条件敏感。结合固定的空间模式和有限使用代理数据的假设，限制了将这些信息源组合起来以重建格陵兰冰川间期循环格陵兰岛气候空间模式的努力。我们通过使用古气候数据同化来创建过去20到000年的年平均温度和降水的独立重建，从而避免了这些限制。我们的方法使用了冰的氧同位素比率和长期冰芯记录的累积速率，并使用从瞬时气候模型模拟得出的空间关系将该信息扩展到格陵兰岛的所有位置。此方法的标准评估指标表明，我们的结果捕获了没有冰芯记录的位置的气候。我们的结果与先前的工作不同，在于在突然的气候转变过程中温度变化的重构空间格局。这表明需要附加的代理数据和附加的瞬态气候模型模拟。我们调查了降水与温度之间的关系，发现它与频率有关且在空间上可变，这表明在冰盖模型中常用的热力学定标方法过于简单。