RAPID: Long-term Trends of the Atlantic Interhemispheric SST Gradient in the CMIP5 20th Century Simulations

RAPID：CMIP5 20 世纪模拟中大西洋半球海温梯度的长期趋势

• 批准号: 1126351
• 负责人: John Chiang
• 金额: $ 3.29万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1126351&HistoricalAwards=false
• 关键词: RAPID; Long; term; Trends; Atlantic

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 examines the secular trend in the Atlantic interhemispheric sea surface temperature (SST) gradient occuring in 20th century observations and climate model simulations. Observations show a trend in the gradient in which the Southern Hemisphere tropical SSTs warm faster than their Northern Hemisphere counterparts. Previous work using an earlier ensemble of climate model simulations suggested that the SST gradient trend is forced in part, perhaps predominantly, by the radiative effects of anthropogenic sulfate aerosols. The behavior of the SST gradient trend in simulations prepared for the AR5 is of particular interest because the new generation of models incorporates significant advances in the simulation of both direct and indirect effects of aerosols. In this project, research focuses on 1) quantifying the magnitude of the SST gradient trend, and assessing the spread in the trend across the different multimodel ensemble members; 2) attributing the cause of the trend; 3) assessing the role of aerosol indirect effects in determining the magnitude of the trend; 4) determining the relative roles of different aerosol types in forcing the trend, particularly sulfate aerosols and black carbon; and 5) understanding the flattening of the trend in the late 20th century. The primary method for identifying the aerosol radiative contribution to the trend consists of comparisons between model simulations forced with all 20th-century climate forcings (including aerosols) and simulations in which only the 20th century increases in greenhouse gas concentrations are used as forcing.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 Atlantic SST gradient exerts a significant influence on the climate of the surrounding landmasses, and is implicated in droughts over the Sahel and northeastern Brazil. The extent to which the SST gradient trend is forced by aerosols, and if so which aerosols are most responsible, is thus of great societal relevance to these regions.

这是16个快速响应（快速）项目之一，这是由亲爱的同事信（NSF 11-006）资助的，鼓励了针对气候变化范围内的诊断模拟诊断分析，该诊断分析是气候变化的第五评估报告（IPCC AR5）。预计这些项目中进行的研究将导致更详细的模型对立，更好地理解健壮的模型行为，并在未来的气候模拟中更好地理解和量化不确定性。 该项目研究了20世纪观测和气候模型模拟中发生的大西洋间海面温度（SST）梯度的世俗趋势。观察结果表明，南半球热带SST的梯度趋势比北半球对应物更快。 先前使用较早的气候模型模拟合奏的工作表明，人为硫酸盐气溶胶的辐射效应，可能主要是部分强迫SST梯度趋势。为AR5准备的模拟中SST梯度趋势的行为特别令人感兴趣，因为新一代模型在模拟气溶胶的直接和间接效应的模拟中都有重大进步。 在该项目中，研究重点是1）量化SST梯度趋势的幅度，并评估趋势中不同多模型集合成员的传播； 2）归因于趋势的原因； 3）评估气溶胶间接效应在确定趋势幅度中的作用； 4）确定不同气溶胶类型在迫使趋势的相对作用，尤其是硫酸盐气溶胶和黑碳； 5）了解20世纪后期趋势的变平。 确定对该趋势的气溶胶辐射贡献的主要方法包括被迫与所有20世纪的气候强迫（包括气溶胶）（包括气溶胶）和模拟仅20世纪增加温室气体浓度增加的模型之间的比较。大西洋SST的梯度对周围陆地的气候产生了重大影响，并与巴西萨赫勒和东北部的干旱有关。 因此，气溶胶强迫SST梯度趋势的程度，如果是，哪种气溶胶最负责，则与这些地区具有很大的社会相关性。