Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing, China.
Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ, USA.
Sci Rep. 2017 Mar 7;7:43429. doi: 10.1038/srep43429.
Black carbon (BC) aerosol strongly absorbs solar radiation, which warms climate. However, accurate estimation of BC's climate effect is limited by the uncertainties of its spatiotemporal distribution, especially over remote oceanic areas. The HIAPER Pole-to-Pole Observation (HIPPO) program from 2009 to 2011 intercepted multiple snapshots of BC profiles over Pacific in various seasons, and revealed a 2 to 5 times overestimate of BC by current global models. In this study, we compared the measurements from aircraft campaigns and satellites, and found a robust association between BC concentrations and satellite-retrieved CO, tropospheric NO, and aerosol optical depth (AOD) (R > 0.8). This establishes a basis to construct a satellite-based column BC approximation (sBC*) over remote oceans. The inferred sBC* shows that Asian outflows in spring bring much more BC aerosols to the mid-Pacific than those occurring in other seasons. In addition, inter-annual variability of sBC* is seen over the Northern Pacific, with abundances varying consistently with the springtime Pacific/North American (PNA) index. Our sBC* dataset infers a widespread overestimation of BC loadings and BC Direct Radiative Forcing by current models over North Pacific, which further suggests that large uncertainties exist on aerosol-climate interactions over other remote oceanic areas beyond Pacific.
黑碳（BC）气溶胶强烈吸收太阳辐射，使气候变暖。然而，BC 气候效应的准确估计受到其时空分布不确定性的限制，特别是在偏远的海洋地区。2009 年至 2011 年期间，HIAPER 极地观测（HIPPO）计划在不同季节多次截获了太平洋上空的 BC 垂直廓线，揭示了当前全球模型对 BC 的估计值高估了 2 到 5 倍。在这项研究中，我们比较了飞机和卫星的测量结果，发现 BC 浓度与卫星反演的 CO、对流层 NO 和气溶胶光学厚度（AOD）之间存在很强的相关性（R > 0.8）。这为在偏远海洋上构建基于卫星的柱 BC 近似值（sBC*）奠定了基础。推断出的 sBC表明，春季亚洲的污染物排放比其他季节向中太平洋输送了更多的 BC 气溶胶。此外，北太平洋上空的 sBC存在年际变化，其丰度与春季太平洋/北美（PNA）指数一致。我们的 sBC*数据集推断出当前模型对北太平洋上的 BC 负荷和 BC 直接辐射强迫存在广泛的高估，这进一步表明，在太平洋以外的其他偏远海洋地区，气溶胶-气候相互作用存在很大的不确定性。
