Ryan J C, Smith L C, Cooley S W, Pearson B, Wever N, Keenan E, Lenaerts J T M
Department of Geography, University of Oregon, Eugene, OR, USA.
Institute at Brown for Environment and Society, Brown University, Providence, RI, USA.
Nat Commun. 2022 Jul 21;13(1):4205. doi: 10.1038/s41467-022-31434-w.
Clouds regulate the Greenland Ice Sheet's surface energy balance through the competing effects of shortwave radiation shading and longwave radiation trapping. However, the relative importance of these effects within Greenland's narrow ablation zone, where nearly all meltwater runoff is produced, remains poorly quantified. Here we use machine learning to merge MODIS, CloudSat, and CALIPSO satellite observations to produce a high-resolution cloud radiative effect product. For the period 2003-2020, we find that a 1% change in cloudiness has little effect (±0.16 W m) on summer net radiative fluxes in the ablation zone because the warming and cooling effects of clouds compensate. However, by 2100 (SSP5-8.5 scenario), radiative fluxes in the ablation zone will become more than twice as sensitive (±0.39 W m) to changes in cloudiness due to reduced surface albedo. Accurate representation of clouds will therefore become increasingly important for forecasting the Greenland Ice Sheet's contribution to global sea-level rise.
云层通过短波辐射遮蔽和长波辐射捕获的竞争效应来调节格陵兰冰原的表面能量平衡。然而，在格陵兰狭窄的消融区内，几乎所有融水径流都产生于此，这些效应的相对重要性仍未得到很好的量化。在这里，我们使用机器学习来合并中分辨率成像光谱仪（MODIS）、云卫星（CloudSat）和云-气溶胶激光雷达和红外路径探测卫星观测（CALIPSO）的卫星观测数据，以生成高分辨率的云辐射效应产品。对于2003年至2020年期间，我们发现云量1%的变化对消融区夏季净辐射通量影响很小（±0.16 W/m²），因为云层的变暖效应和冷却效应相互抵消。然而，到2100年（共享社会经济路径5-8.5情景），由于地表反照率降低，消融区的辐射通量对云量变化的敏感度将增加一倍多（±0.39 W/m²）。因此，准确呈现云层对于预测格陵兰冰原对全球海平面上升的贡献将变得越来越重要。
