Collaborative Research: Observationally-Constrained Estimates of Effective Radiative Forcing from Aerosol Radiation Interactions

太阳对地球的加热受到人类活动释放的气溶胶的影响，这些活动包括农业（例如收获后焚烧农作物秸秆）、发电（包括反射太阳辐射的硫酸盐气溶胶和吸收太阳辐射的黑碳气溶胶）和运输。这些人为气溶胶的辐射效应很难量化，它们的气候效应是未来气候变化预估中最大的不确定因素之一。该项目的目标是利用现有的最佳卫星和地面数据集，对人为气溶胶造成的辐射强迫进行基于观测的估计。更具体地说，这项研究试图对气溶胶-辐射相互作用（ERFari）产生的有效辐射强迫作出估计，其中既包括气溶胶的辐射效应，也包括由于气溶胶辐射加热引起的云层变化而导致的辐射强迫的变化。例如，由于黑碳气溶胶（烟灰）吸收太阳辐射而产生的加热会导致云的“燃烧”，从而使更多的阳光照射到地面。用于确定气溶胶量、垂直剖面和辐射参数的数据来自几个卫星任务（MODIS、CALIPSO/CALIOP激光雷达、MISR、CERES）和地面AERONET网络。气溶胶的数量和性质结合辐射传输模式（MACR）来确定气溶胶的辐射强迫。然后将辐射强迫用作全球气候模式的输入，据此确定气溶胶对云辐射强迫的进一步影响的估计。然后将模式导出的云辐射特性估计值与进一步的卫星云观测进行比较。该项目的一个关键假设是，如果可以排除已知的细模气溶胶的自然来源（灰尘、海洋硫酸盐、海盐），则细模气溶胶可以用作人为气溶胶的替代品。由于人为气溶胶作为区域和全球气候强迫的潜在重要性，这项工作具有更广泛的影响。减少这种气候强迫的巨大不确定性的工作可以更好地预测未来气候变化及其对人类活动的影响。此外，该项目将支持一名研究生，并为一所种族多元化大学的本科生提供研究机会。其中一个pi还通过当地的非营利组织向当地的K-12学生提供服务。

The solar heating of the Earth is affected by aerosols emitted from human activites including agriculture (for instance the burning of crop residue after the harvest), power generation (including both sulfate aerosol which reflects solar radiation and black carbon aerosol that absorbs it), and transportation. The radiative effects of these anthropogenic aerosols are hard to quantify, and their climatic effect is among the largest uncertainties in projections of future climate change. The goal of this project is to develop observationally-based estimates of the radiative forcing due to anthropogenic aerosols using the best available satellite and surface-based datasets. More specifically, the research seeks to produce estimates of the effective radiative forcing from aerosol-radiation interactions (ERFari), which includes both the radiative effects of the aerosols and the changes in radiative forcing due to changes in clouds brought about by aerosol radiative heating. For example, the heating due to absorption of solar radiation by black carbon aerosols (soot) can lead to the "burn off" of clouds, resulting in more sunlight reaching the ground. Data used to determine aerosol amounts, vertical profiles, and radiative parameters comes from several satellite missions ( (MODIS, the CALIPSO/CALIOP lidar, MISR, CERES) and from the ground-based AERONET network. The aerosol amounts and properties are used in combination with a radiative transfer model (MACR) to determine the aerosol radiative forcing. The radiative forcing is then used as an input to global climate models, from which estimates of the further impact of aerosols on cloud radiative forcing are determined. Model-derived estimates of the cloud radiative properties are then compared to further satellite cloud observations. A key assumption of the project is that fine-mode aerosols can be used as a proxy for anthropogenic aerosols, provided that known natural sources of fine-mode aerosol (dust, marine sulfate, sea salt) can be factored out. The work has broader impacts due to the potential importance of anthropogenic aerosol as a regional and global climate forcing. Work to reduce the large uncertainty in this climate forcing could lead to better projections of future climate change and its impacts on human activities. In addition, the project would support a graduate student and provide a research opportunity for an undergraduate student at an ethnically diverse university. One of the PIs also performs outreach to local K-12 students through a local nonprofit organization.