RAPID: Warming Holes--Can Climate Models Represent the Variability and Sources of Regional Temperature Trends in the Continental United States?

这是16个快速反应（RAPID）项目之一，作为亲爱的同事信（NSF 11-006）的结果，鼓励对政府间气候变化专门委员会第五次评估报告（IPCC AR 5）准备的气候模型模拟进行诊断分析。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，更好地理解强大的模式行为，更好地理解和量化未来气候模拟中的不确定性。这个项目解决了美国中西部地区夏季温度趋势为零或负的区域，通常被称为“变暖洞”。 在该赠款下进行的工作旨在确定暖洞是否是由于与低频模式相关的自然变率造成的，或者是否是由某些人为气候强迫（例如气溶胶）造成的。 该项目有三个主要任务：1）评估为第五次评估报告准备的20世纪气候模拟能够再现变暖洞的程度; 2）评估变暖洞（定义为数十年来变暖减少的地区）是否被模型的内部变化所捕获，如果是这样，它们是否发生在首选地点，如美国中西部; 3）确定模式模拟是否捕捉到了观测到的美国区域温度、云和降水与全球海表温度遥相关之间的局部关系。该项目的更广泛影响在于其对IPCC AR 5的支持，该AR 5旨在为全球决策者提供有关气候变化及其后果的信息。 气候模式代表暖洞的能力对于评估未来中西部温度预测的可靠性是很重要的。

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.This project addresses the region of zero or negative summertiime temperature trends which occurs over the midwestern US and is commonly referred to as a "warming hole". Work performed under the grant seeks to determine whether the warming hole occurs as the result of the natural variability associated with low-frequency modes, or whether it is caused by some anthropogenic climate forcing (aerosols, for example). The project has three main tasks: 1) evaluating the extent to which the 20th century climate simulations prepared for the AR5 are capable of reproducing the warming hole; 2) assessing whether warming holes, defined as regions of reduced warming over multiple decades, are captured in the internal variability of the models, and, if so, whether they occur in preferred locations, such as the U.S. Midwest; 3) determining whether the model simulations capture the observed local relationships between regional U.S. temperatures and clouds and precipitation and the global teleconnections to sea-surface temperatures.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. The ability of climate models to represent the warming hole is important for assessing the reliability of future midwest temperature projections from the models.