CITE-3 Electra In-Situ Aerosol Data

CITE-3_Aerosol_AircraftInSitu_Electra_Data is the in-situ trace gas data collected onboard the NASA Electra aircraft Chemical Instrumentation Test and Evaluation - 3 (CITE-3) suborbital campaign. Data using chemiluminescence are featured in this collection. Data collection for this product is complete.

During 1983-2001, NASA conducted a collection of field campaigns as a part of the Global Tropospheric Experiment (GTE) to develop advanced instrumentation to measure critical atmospheric trace gases and quantify their sources, sinks, and distribution. Among those were the Chemical Instrumentation Test and Evaluation (CITE) missions, which had the overarching goal to test and evaluate the instruments developed for the GTE missions. To accomplish this objective, the CITE missions adopted the methodology of conducting intercomparisons of airborne measurements obtained for the same species by instruments utilizing fundamentally different detection principles (Hoell et al., 1990). The third phase of the CITE mission, CITE 3, occurred in the North and tropical Atlantic Ocean from August-September 1989. Its primary objective was to test and evaluate the capacity to collect reliable measurements of the following sulfur species: sulfur dioxide (SO2), dimethyl sulfide (DMS), carbonyl sulfide (COS), carbon disulfide (CS2), and hydrogen sulfide (H2S). The secondary objective of CITE 3 was to determine the abundance and distribution of major sulfur species over a wide range of atmospheric conditions, including altitude, solar flux levels, atmospheric mixing ratios, and surface source strengths of sulfur in a predominantly marine environment (Hoell et al., 1993).

CITE 3 utilized the NASA Electra research aircraft equipped with a suite of instruments for sulfur and ancillary measurements. The two main objectives were addressed through intercomparisons of airborne measurements obtained for the same species but utilizing fundamentally different detection principles in order to have multiple measurements of each of the sulfur species. In some instances, the same detection principle was used, but the method of sample collection and/or analysis procedures were different. A complete payload had the potential of five techniques for SO2, six techniques for DMS, and three techniques for H2S, CS2, and COS. However, due to operational problems or team decisions to focus on specific species during flights, not all measurement techniques were employed at all times (Hoell et al., 1993). There were three phases of field activity in this campaign: (1) intercomparison of sulfur calibration standards, (2) measurements in ambient air over the Northern Atlantic Ocean, and (3) measurements in ambient air over the tropical Atlantic Ocean. Cite 3 was based out of NASA Wallops Flight Facility in Virginia, USA and Natal, Brazil. Each base of operation provided a different environment for intercomparison. Air masses at NAS Wallops Flight Facility were influenced by anthropogenic emissions along the eastern United States compared to the relatively clean marine boundary layer over the ocean off the coast of Natal. As part of the Natal deployment, ozonesondes were launched from the Natal area to provide data on the general state of the atmosphere as well as serve as a frame of reference when compared to the seasonally averaged ozone data from this site.

seasonally averaged ozone data from this site. Sulfur gases and their reaction products play important roles in the chemistry of the global troposphere as well as the biogeochemical sulfur cycle. The sulfur database from CITE 3, and the results from both intercomparison studies and photochemical budget studies, significantly enhanced the ability to evaluate the confidence in the existing databases. Detailed description related to the motivation, implementation, and instrument payloads are available in the CITE 3 overview paper. A collection of the publications based on CITE 3 observations are available in the Journal of Geophysical Research special issue: Chemical Instrumentation Test and Evaluation (CITE 3).

CITE-3_Aerosol_AircraftInSitu_Electra_Data 数据集是美国国家航空航天局（National Aeronautics and Space Administration，NASA）“化学仪器测试与评估-3（Chemical Instrumentation Test and Evaluation -3, CITE-3）”亚轨道科考任务中，搭载于NASA Electra研究飞机获取的原位痕量气体观测数据。本数据集收录了基于化学发光法的观测数据，该产品的数据采集工作已全部完成。

1983年至2001年间，NASA作为全球对流层实验（Global Tropospheric Experiment, GTE）的一部分开展了一系列野外科考任务，旨在研发可精准测量关键大气痕量气体的先进仪器，并量化其源、汇与空间分布特征。其中包括化学仪器测试与评估（Chemical Instrumentation Test and Evaluation, CITE）系列任务，其核心目标是对为GTE任务研发的各类仪器开展系统性测试与性能评估。为达成该目标，CITE系列任务采用了针对同一观测物种，对比采用原理截然不同的探测仪器所获取的机载测量结果的方法（Hoell等，1990）。

CITE任务的第三阶段CITE 3于1989年8月至9月在北大西洋及热带大西洋海域开展，其首要目标是测试并评估针对以下含硫物种的可靠测量能力：二氧化硫（sulfur dioxide, SO₂）、二甲基硫（dimethyl sulfide, DMS）、羰基硫（carbonyl sulfide, COS）、二硫化碳（carbon disulfide, CS₂）以及硫化氢（hydrogen sulfide, H₂S）。CITE 3的次要目标是在涵盖海拔高度、太阳辐射通量水平、大气混合比以及以海洋为主的环境中硫的地表源强度等多种大气条件下，明确主要含硫物种的丰度与空间分布（Hoell等，1993）。

CITE 3任务使用了搭载有一套硫及辅助测量仪器的NASA Electra研究飞机。通过对同一观测物种采用原理截然不同的探测仪器所获取的机载测量结果进行交叉比对，可实现对每种含硫物种的多次独立测量，以此达成两项核心目标。在部分案例中，尽管采用了相同的探测原理，但样品采集方法和/或分析流程存在差异。完整的观测载荷理论上可搭载5种SO₂测量技术、6种DMS测量技术以及3种分别用于H₂S、CS₂和COS的测量技术。但受限于作业故障或飞行期间团队针对特定物种的观测优先级调整，并非所有测量技术在全程都得以启用（Hoell等，1993）。本次科考任务分为三个野外作业阶段：（1）含硫校准标准品的交叉比对；（2）北大西洋海域上空的环境空气测量；（3）热带大西洋海域上空的环境空气测量。

CITE 3任务的运营基地为美国弗吉尼亚州NASA沃洛普斯飞行设施（Wallops Flight Facility）以及巴西纳塔尔（Natal）。每个运营基地为比对实验提供了差异化的环境背景：沃洛普斯飞行设施的气团受到美国东部沿岸人为排放的影响，而纳塔尔沿岸海域上空则为相对洁净的海洋边界层。作为纳塔尔部署任务的一部分，研究人员在纳塔尔地区发射了臭氧探空仪，以获取大气整体状态数据，并作为参考框架与该站点的季节平均臭氧数据进行比对。

含硫气体及其反应产物在全球对流层化学以及生物地球化学硫循环中发挥着至关重要的作用。CITE 3任务产出的含硫数据库，以及交叉比对研究与光化学收支研究的成果，显著提升了对现有大气数据库的可信度评估能力。关于任务动因、实施细节以及仪器载荷的详细说明可参见CITE 3任务综述论文。基于CITE 3观测结果的系列研究论文收录于《地球物理研究期刊》（Journal of Geophysical Research）特刊："Chemical Instrumentation Test and Evaluation (CITE 3)"。