RAPID: Evaluation of Climate Models in the Southeast Pacific Marine Stratocumulus Region

这是政府间气候变化专门委员会第五次评估报告（IPCC AR5）中鼓励对气候模式模拟进行诊断分析的致同事信（NSF 11-006）资助的16个快速响应（Rapid）项目之一。在这些项目中进行的研究预计将导致更详细的模式相互比较，更好地理解稳健模式行为，更好地理解和量化未来气候模拟中的不确定性。海洋层积云（mSc）云出现在大陆西侧的亚热带海洋区域，由于其对入射太阳辐射的强烈反射，对地球气候有冷却作用。由mSc云主导的区域已被证明是气候模式中热带云反馈的巨大不确定性的重要驱动因素，并且是模式模拟和观测之间巨大差异的原因。在这项资助下进行的研究考虑了模型模拟中的mSc特性，并将其与最近从包括CloudSat剖面雷达在内的卫星仪器观测到的云特性进行了比较。研究了短波云辐射强迫对海面温度变化的响应，并将模式云诊断变量与卫星观测进行了比较，以确定造成低云反馈不确定性的潜在过程。该项目的更广泛影响在于它对IPCC第五次评估报告的支持，该报告旨在向全球决策者提供有关气候变化及其后果的信息。云反馈可以在确定全球变暖在多大程度上来自温室气体浓度的预期增加方面发挥重要作用，因此，更好地了解云反馈和更好地在气候模式中表示云的研究将有助于了解人为气候变化的可能严重程度。

This is one of 16 Rapid Response (RAPID) projects funded as the result of a Dear Colleague Letter (NSF 11-006) encouraging diagnostic analyses of climate model simulations prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5). Research conducted in these projects is expected to lead to more detailed model intercomparisons, better understanding of robust model behaviors, and better understanding and quantification of uncertainty in future climate simulations.Marine stratocumulus (mSc) clouds occur in subtropical oceanic regions off the west sides of continents, and have a cooling effect on the earth's climate because of their strong reflection of incoming solar radiation. Regions dominated by mSc clouds have been shown to be an important driver of the large uncertainties in tropical cloud feedbacks in climate models, and are responsible for the large differences between model simulations and observations. Research conducted under this grant considers mSc properties in model simulations, and compares them with cloud properties found in recent observations from satellite instruments including the CloudSat Profiling Radar. The response of shortwave cloud radiative forcing to changes in sea surface temperature is examined, and model cloud diagnostic variables are compared to satellite observations to determine the underlying processes responsible for uncertainties in low-cloud feeback. The broader impact of the project lies in its support of the IPCC AR5, which is intended to provide information on climate change and its consequences to decision makers worldwide. Cloud feedbacks could play an important role in determining how much global warming comes from the expected increases in greenhouse gas concentrations, so research leading to better understanding of cloud feedbacks and better representation of clouds in climate models would be beneficial for understanding the likely severity of anthropogenic climate change.