A convolution of observational and model data to estimate age of air spectra in the northern hemispheric lower stratosphere
A convolution of observational and model data to estimate age of air spectra in the northern hemispheric lower stratosphere
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DOI：
10.5194/acp-2020-167
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发表时间：
2020-03
影响因子：
6.3
通讯作者：
M. Hauck;H. Bönisch;P. Hoor;T. Keber;F. Ploeger;T. Schuck;A. Engel
中科院分区：
文献类型：
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作者：
M. Hauck;H. Bönisch;P. Hoor;T. Keber;F. Ploeger;T. Schuck;A. Engel
抽象的。从大气测量中推导空气平均年龄（AoA）和年龄谱仍然是一个挑战，往往需要大气模型的输出。本研究试图尽量减少模型输出的直接影响，并提出了一个以前建立的反演方法的扩展和应用，从混合比例的长期和短期的微量气体的年龄谱。为了精确描述跨对流层顶的输送过程，将逆方法扩展到包括热带和热带外对流层顶的平流层中的空气卷吸。我们首先使用模拟与平流层的化学拉格朗日模型（CLaMS）提供一个一般的概念证明的扩展原则在一个可控的和一致的环境中，该方法被应用到一组理想化的10个微量气体与预定义的恒定寿命和参考模型的年龄谱。在研究的第二部分中，我们将扩展的逆方法应用于大气测量的多个长寿命和短寿命的微量气体上测量的高海拔和长距离（HALO）研究飞机在两个研究活动POLSTRACC-GW-LCYCLE-SALSA（PGS）和波驱动等熵交换（WISE）。由于一些观测到的物种在平流层中经历了显着的损失过程，引入蒙特卡罗模拟检索年龄谱和化学寿命逐步的方式，并考虑到大的不确定性。结果表明，在理想模式情景下，反演方法在年和季节尺度上都能稳健地反演年龄谱。扩展到多入口区域是合理的，因为我们的CLaMS模拟显示，在模式中，最低平流层中50%至70%的空气每年平均通过对流层顶外（30-90 ° N和S）进入。当应用于PGS和WISE的观测数据时，该方法得到的年龄谱和平均AoA具有有意义的空间分布和定量范围，但有很大的不确定性。结果表明，夹带的新鲜对流层空气在两个运动之前达到峰值，但较低的平均AoA的WISE比PGS数据。PGS和WISE的所有检索到的年龄谱的矩的比率被发现范围在0.52和2.81年之间。我们的结论是，该方法得出合理的和一致的年龄谱使用的化学活性痕量气体的观测。我们的研究结果可能有助于在未来的研究中改进运输与年龄谱的评估。
Abstract. Derivation of mean age of air (AoA) and age spectra from atmospheric measurements remains a challenge and often requires output from atmospheric models. This study tries to minimize the direct influence of model output and presents an extension and application of a previously established inversion method to derive age spectra from mixing ratios of long- and short-lived trace gases. For a precise description of cross-tropopause transport processes, the inverse method is extended to incorporate air entrainment into the stratosphere across the tropical and extratropical tropopause. We first use simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) to provide a general proof of concept of the extended principle in a controllable and consistent environment, where the method is applied to an idealized set of 10 trace gases with predefined constant lifetimes and compared to reference model age spectra. In the second part of the study we apply the extended inverse method to atmospheric measurements of multiple long- and short-lived trace gases measured aboard the High Altitude and Long Range (HALO) research aircraft during the two research campaigns POLSTRACC–GW-LCYCLE–SALSA (PGS) and Wave-driven Isentropic Exchange (WISE). As some of the observed species undergo significant loss processes in the stratosphere, a Monte Carlo simulation is introduced to retrieve age spectra and chemical lifetimes in stepwise fashion and to account for the large uncertainties. Results show that in the idealized model scenario the inverse method retrieves age spectra robustly on annual and seasonal scales. The extension to multiple entry regions proves reasonable as our CLaMS simulations reveal that in the model between 50 % and 70 % of air in the lowermost stratosphere has entered through the extratropical tropopause (30–90∘ N and S) on annual average. When applied to observational data of PGS and WISE, the method derives age spectra and mean AoA with meaningful spatial distributions and quantitative range, yet large uncertainties. Results indicate that entrainment of fresh tropospheric air across both the extratropical and tropical tropopause peaked prior to both campaigns, but with lower mean AoA for WISE than PGS data. The ratio of moments for all retrieved age spectra for PGS and WISE is found to range between 0.52 and 2.81 years. We conclude that the method derives reasonable and consistent age spectra using observations of chemically active trace gases. Our findings might contribute to an improved assessment of transport with age spectra in future studies.