QUANTifying stratospheric circulation Impacts on Tropospheric Emission Estimates (QUANTITEE)

量化平流层环流对对流层排放估算的影响 (QUANTITEE)

• 批准号: 462476233
• 负责人: Professor Dr. Felix Plöger
• 金额: --
• 依托单位: IEK-7: Stratosphäre
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/462476233?language=en
• 关键词: QUANTifying; stratospheric; circulation; Impacts; Tropospheric

Recent studies have provided evidence that emissions of one of the most important chlorofluorocarbons (CFCs), i.e., CFC-11, have started to increase again since around 2012, implying a potentially severe threat to the stratospheric ozone layer. However, estimates of CFC emissions are prone to large uncertainty caused by changes in the stratospheric circulation which, in turn, are insufficiently constrained in current atmospheric models and reanalyses. Moreover, the methodologies to constrain the representation of stratospheric circulation patterns and variations in stratospheric models with observations are limited.The goal of this project is to enhance the understanding of the impacts of inter-annual to decadal variability in stratospheric transport on tropospheric variations of long-lived trace gases, with focus on CFCs. For this reason, we will evaluate and further improve novel methods for deducing stratospheric age of air spectra, the transit time distribution through the stratosphere which is an advantageous diagnostic for stratospheric transport. In a first step, the method evaluation will be carried out in a model environment. Three different methods for calculating age spectra from mixing ratios of chemical species will be compared, based on (i) an inverse Gaussian parameterization of the spectrum, (ii) an improved parameterization, and (iii) a direct inversion approach. A careful “proof of concept” will be carried out for all three methods by comparison to model age spectra calculated with the (exact) pulse method in the Chemical Lagrangian Model of the Stratosphere (CLaMS). In a second step, the methods will be applied to high-resolution in-situ trace gas measurements on air samples collected in the stratosphere, both with the more conventional aircraft samplers and a new technique based on AirCores. Hence, age spectra will be calculated from a combination of new age spectra simulation techniques and novel observations, providing unprecedented constraints on variations of stratospheric transport. A comparison to model age spectra from simulations driven by different meteorological reanalyses, including newest (ERA5) and older products (ERA-Interim, MERRA-2, JRA-55), will allow assessing the reliability of the representation of stratospheric transport variations. Finally, transport variability (e.g., related to the QBO) will be analyzed and the effects on trace gas composition in the lower stratosphere and on tropospheric trends will be quantified. The improved methods to infer tropospheric budgets will be a legacy tool for the scientific community to better constrain future emissions of many long-lived ozone-depleting substances and greenhouse gases.

最近的研究表明，最重要的氯氟化碳之一，即氟氯化碳-11的排放量自2012年左右开始再次增加，这意味着对平流层臭氧层的潜在严重威胁。然而，由于平流层环流的变化，对氟氯化碳排放量的估计容易产生很大的不确定性，而在目前的大气模型和再分析中，这种不确定性又是不够的。该项目的目标是加强对平流层输送年际至年代际变化对长期痕量气体对流层变化影响的了解，重点是氯氟烃。为此，我们将评估和进一步改进推算平流层大气光谱年龄的新方法，平流层通过平流层的时间分布是对平流层输送有利的诊断。在第一步中，将在模型环境中进行方法评估。根据化学物质的混合比计算年龄谱的三种不同方法将被比较，基于(I)谱的逆高斯参数化法，(Ii)改进的参数化法和(Iii)直接反演法。将通过与平流层化学拉格朗日模型(CLAMS)中(精确)脉冲法计算的模型年龄谱进行比较，对所有三种方法进行仔细的“概念证明”。在第二步，这些方法将被应用于在平流层收集的空气样本的高分辨率现场痕量气体测量，既有更传统的飞机采样器，也有基于AirCores的新技术。因此，年龄谱将通过新的年龄谱模拟技术和新的观测相结合来计算，从而对平流层输送的变化提供前所未有的限制。与不同气象再分析推动的模拟的年龄谱进行比较，包括最新的(ERA5)和较旧的产品(ERA-临时、MERRA-2、JRA-55)，将能够评估表示平流层输送变化的可靠性。最后，将分析输送的可变性(例如，与QBO有关)，并将量化对低平流层微量气体成分和对流层趋势的影响。推算对流层预算的改进方法将成为科学界更好地限制许多长期消耗臭氧物质和温室气体未来排放的遗留工具。