Performance improvement and airborne employment of a highly sensitive tunable-diode laser spectrometer for in-situ measurements of the isotopic composition of water vapor

用于原位测量水蒸气同位素组成的高灵敏度可调谐二极管激光光谱仪的性能改进和机载使用

• 批准号: 47182023
• 负责人: Dr.-Ing. Christoph Dyroff
• 金额: --
• 依托单位: IMK - Atmosphärische Spurengase und Fernerkundung
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/47182023?language=en
• 关键词: Performance; improvement; airborne; employment; highly

Gavin Schmidt calls water isotopologues “the most super-duper fantastic thing ever” [Tollefson, J. (2008), Vapour spies to reveal climate clues , Nature 455, 714-715]. Indeed, the measurement of isotope ratios in water vapor (H2O) can significantly enhance our understanding of many crucial processes in which atmospheric water is involved. The H2O isotope ratios collect and conserve the H2O evaporation and condensation history prior to sampling. They thus contain supplementary information on the hydrological atmospheric cycle which H2O-concentration measurements cannot provide. Furthermore, due to the considerable temperature-dependent isotope fractionation, H2O-isotope ratios of cloud particles are a measure of the supersaturation present during cloud formation. While a number of satellite measurements have recently been realized, they only provide the global picture. Airborne in-situ measurements − providing the often necessary high spatial resolution − have very scarcely been performed, and only about four instruments exist worldwide, one of which is the tunable diode-laser spectrometer ISOWAT. The goal of the present proposal is the performance enhancement, detailed characterization, and airborne employment of the diode-laser spectrometer ISOWAT for in-situ measurements of water-isotope ratios (18O, D). ISOWAT was developed during the foregoing DFG HALO funding period (ZA 550/1-1). The instrument already outperforms the very few other instruments worldwide in terms of its detection limit and size/weight, which is documented by a strong interest of a group of US scientists led by Dr. R. Talbot (University of New Hampshire) to fly a copy of ISOWAT aboard the NASA WB-57. However, we believe that we can improve the performance of ISOWAT and thus even enhance the bandwidth of potential scientific achievements. ISOWAT will be highly useful for a number of future HALO missions, including ML-CIRRUS, TACTS, and POLSTRACC, for which ISOWAT is part of the payload. Isotope-ratio measurements with ISOWAT are directly linked to the main research topics of the present call for proposals by the DFG, namely to Clouds and Precipitation as well as Transport and Dynamics in the Troposphere and Lower Stratosphere. For example, the temperature history prior to sampling determines the H2O-isotope ratios enabling e.g. a direct distinction between (i) slow ascent and cooling with resulting condensation and precipitation being in equilibration with the remaining vapor (named as Rayleigh distillation that leads to very low -values), and (ii) fast convective lofting with potential overshooting in the lower stratosphere which results in much higher -values. Furthermore, our isotope-ratio measurements will provide an indirect link to stratospheric Photochemistry (in combination with remote sensing instruments) as they will provide the isotope ratio of the water vapor entering the stratosphere. Thus, the H2O-isotope ratios are a powerful tracer to study the stratospheric water budget. ISOWAT will hence contribute to at least 50% of the scientific questions to be answered by HALO campaigns.

加文·施密特称水的同位素是“有史以来最神奇的东西”[Tollefson， J.(2008)，蒸汽探子揭示气候线索，《自然》455,714-715]。事实上，测量水蒸气（H2O）中的同位素比率可以显著提高我们对大气中水所涉及的许多关键过程的理解。水同位素比值收集和保存了采样前的水蒸发和凝结历史。因此，它们包含了关于水文大气循环的补充资料，这是水浓度测量无法提供的。此外，由于相当大的温度依赖同位素分馏，云颗粒的h2o -同位素比值是云形成过程中存在过饱和度的量度。虽然最近实现了一些卫星测量，但它们只提供了全球的情况。提供通常必需的高空间分辨率的机载原位测量很少被执行，全世界只有大约四种仪器存在，其中之一是可调谐二极管激光光谱仪。本提案的目标是性能增强，详细表征和机载使用的二极管激光光谱仪ISOWAT的水同位素比的原位测量（<s:1> 18O, <s:1> D）。ISOWAT是在上述DFG HALO资助期间（ZA 550/1-1）开发的。该仪器在检测极限和尺寸/重量方面已经超过了世界上极少数其他仪器，这是由Dr. R. Talbot（新罕布什尔大学）领导的一组美国科学家对NASA WB-57上飞行ISOWAT副本的强烈兴趣所记录的。然而，我们相信我们可以提高ISOWAT的性能，从而甚至提高潜在科学成果的带宽。ISOWAT将在未来的一些HALO任务中非常有用，包括ML-CIRRUS、TACTS和POLSTRACC， ISOWAT是有效载荷的一部分。利用ISOWAT进行的同位素比率测量与DFG目前征求建议的主要研究课题直接相关，即云和降水以及对流层和平流层下层的运输和动力学。例如，采样前的温度历史决定了h2o -同位素比率，从而能够直接区分(i)缓慢上升和冷却，由此产生的冷凝和降水与剩余蒸汽平衡（称为瑞利蒸馏，导致非常低的蒸发系数），以及（ii）快速对流蒸发，在平流层下层有可能过冲，导致更高的蒸发系数。此外，我们的同位素比率测量将提供与平流层光化学（与遥感仪器结合）的间接联系，因为它们将提供进入平流层的水蒸气的同位素比率。因此，水同位素比值是研究平流层水收支的有力示踪剂。因此，ISOWAT将贡献至少50%的科学问题，这些问题将由HALO运动来回答。

项目成果

Empirical validation and proof of added value of MUSICA's tropospheric δD remote sensing products

MUSICA对流层δD遥感产品附加值的实证验证和证明

• DOI: 10.5194/amt-8-483-2015
• 发表时间: 2015
• 期刊: Atmospheric Measurement Techniques
• 影响因子: 3.8
• 作者: Schneider;González;Dyroff;Christner;Wiegele;Barthlott;García;Sepúlveda;Andrey;Blumenstock;Guirado;Rodríguez
• 通讯作者: Rodríguez