SGER: Evaluation of Surface Solar Irradiance in Coupled Climate Models

将对卫星观测和地面下流辐照度的现场测量进行分析，并与19世纪末和20世纪的全球大气环流耦合模式模拟进行比较，以评估模式的气候学、可变性以及云和气溶胶效应。进入地面的短波辐照度是海洋/冰和陆面子模式的一种驱动机制，虽然它直接受到大气中的物理因素，如云、气溶胶、水蒸气、臭氧和其他气体的影响，但它只受到海洋/冰/陆地的间接影响。因此，气溶胶和云的变化对下行短波地表辐照度有很强的直接信号，这是很容易解释的。与此同时，地表太阳辐照度及其与云和气溶胶的联系是云反馈循环的一个重要部分。此外，科学界对地表入射太阳辐照度的长期变化越来越感兴趣。观测表明，从1961年到1990年，全球各观测站的太阳辐照度最近下降了约4%，这可能是由于气溶胶浓度的变化和云的变化所致。这被描述为全球变暗效应。目前的研究(来自卫星观测)表明，从20世纪80年代末到90年代，这种效应发生了逆转。PIS将使用两个数据集，代表来自卫星和现场测量的两种不同类别的数据检索方法。他们将把观测到的气候学和地表下行短波通量的可变性与四个耦合气候模型--戈达德空间研究所(GISS)模型和两个海洋子模型--地球物理流体动力学实验室(GFDL)模型和国家大气研究中心社区气候系统模型(CCSM-3)--在所有分辨率的时间和空间尺度上进行比较。由于这些模型使用不同的气溶胶数据集和云参数化(有些使用间接的云-气溶胶效应)，模型间对表面太阳辐照度的比较将对每个模型表示云和气溶胶影响的质量有指导意义。PIS将a)评估模式地表向下流动短波通量的长期变异性和趋势，并将其与观测值进行比较；b)评估模式中的气溶胶和云层效应；c)检查模式模拟特定事件(火山喷发和厄尔尼诺现象)的能力。更广泛的影响：这项研究很重要，因为它有可能提高气候预测模型的质量，这将有利于环境管理和决策等社会活动。这是美国气候变化科学计划气候变异性和可预测性计划(CLIVAR)下的一项拨款。

Observations from satellites and in situ measurements of surface downwelling irradiance will be analyzed and compared with global general circulation coupled model simulations of the late 19th century and 20th century runs to evaluate the model climatology, variability and cloud and aerosol effects. The incoming shortwave irradiance at the surface is one driving mechanism of the ocean/ice and land submodels and while it is directly affected by the physics in the atmosphere, such as clouds, aerosols, water vapor, ozone and other gases, it is only indirectly affected by the ocean/ice/land. Hence, aerosol and cloud variations have a strong direct signal on the downwelling shortwave surface irradiance, which can be easily interpreted. At the same time, surface solar irradiance and its link to clouds and aerosols represents one crucial part of the cloud feedback loop. Furthermore, there has been increased interest in the scientific community regarding the long-term variability of the surface incoming solar irradiance. Observations show that solar irradiance has recently been decreasing in stations worldwide by about 4% from 1961-1990, possibly due to changed aerosol concentrations and cloud variations. This has been described as a global dimming effect. Current research (from satellite observations) shows a reversal of this effect from the late 1980s and during the 1990s. The PIs will use two data sets, which represent two different classes of data retrieval methods, from satellites and in situ measurements. They will compare the observed climatology and variability of the surface downwelling shortwave flux to four coupled climate models, the Goddard Institute for Space Studies (GISS) model with two ocean submodels, the Geophysical Fluid Dynamics Laboratory (GFDL) model and the National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM-3), on all resolved temporal and spatial scales. Since the models use different aerosol datasets and cloud parameterizations (some use indirect cloud-aerosol effects) the inter-model comparisons of the solar irradiance at the surface will be instructive of the quality of each models' representation of cloud and aerosol impacts. The PIs will a) assess the long-term variability and trend of the model downwelling shortwave flux at the surface and compare it to observations, b) assess the aerosol and cloud effects in the models and, c) examine the models' capability in simulating specific events (volcanic eruptions and El Nino conditions). Broader Impacts: This research is important because it has the potential to improve the quality of climate prediction models, which would be a benefit to societal activities, such as, environmental management and decision-making.This is a grant under the U.S. Climate Change Science Program's, Climate Variability and Predictability Program (CLIVAR).