DOAS (Differential Optical Absorption Spectroscopy) Measurements during CONTRAST (CONvective Transport of Active Species in the Tropics)

作为更大的对比(热带活动物种对流输送)测量活动的一部分，该测量活动的主要目标是测量活性化学物质进入西太平洋暖池上空对流层顶过渡层(TTL)的输送，科罗拉多大学博尔德分校的研究人员试图测量一些微量卤素化合物的柱丰度，如溴氧化物(Bro)、氧化碘(IO)、二氧化氯(OClO)以及其他痕量气体物种。在北方冬季，含有这些反应气体的地面对流层气团可能会优先通过强烈的热带对流高层输送到太平洋暖池地区的对流层低平流层。在这里，它们可能会影响平流层下部的化学，包括它的臭氧化学。对流层上层独特的低臭氧环境预计会产生非常少量的OH自由基，这可能会延长反应气体的寿命，其主要损失是通过羟基(OH)自由基氧化。TTL中同时发生的深对流和延长的有机化合物寿命可能会对平流层卤素的预算产生重大影响。对比实验的时间安排是为了利用计划在相同时间和地理位置进行的两项国际航空研究的优势。这些项目是NASA EV1项目ATTREX(机载热带对流层顶实验)和欧洲CAST(热带地区协调机载研究)。利用互补的仪器有效载荷，NSF GV、NASA全球鹰和英国BAE146的协调飞行将提供对热带西太平洋从表面到19公里的完整大气层柱的前所未有的检查。

As part of the larger CONTRAST (Convective Transport of Active Species in the Tropics) measurement campaign, which has the main objective of measuring the transport of reactive chemical species into the topical Tropopause Transition Layer (TTL) over the western Pacific warm pool, University of Colorado-Boulder researchers seek to measure the column abundances of a number of trace halogen compounds e.g., bromine oxide (BrO), iodine oxide (IO), chlorine dioxide (OClO) along with other trace gas species.During northern winter, surface tropospheric air masses containing these reactive gases may be preferentially transported by intense tropical convection high into the TTL lower stratosphere over the region of the Pacific warm pool. Here they may impact the chemistry of the lower stratosphere, including its ozone chemistry. The unique low-ozone environments in the upper troposphere are expected to result in very small levels of OH radicals, which can be expected to increase the lifetime of reactive gases whose main loss is through hydroxyl (OH) radical oxidation. The simultaneous occurrence of deep convection and prolonged lifetime of organic compounds in the TTL can have significant impact on the stratospheric halogen budget.The timing of the CONTRAST experiment has been designed to take advantage of collaborations with two international airborne studies planned for the same time and geographic location. These are the NASA EV1 project ATTREX (Airborne Tropical Tropopause Experiment) and the European CAST (Coordinated Airborne Studies in the Tropics). With complementary instrument payloads, coordinated flights of the NSF GV, the NASA Global Hawk and the UK BAE146 will provide an unprecedented examination of the full atmospheric column, from surface to 19 km, in the Tropical Western Pacific.