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

作为更大的对流传输（热带地区活动物质的对流传输）测量活动的一部分，其主要目标是测量反应性化学物质进入西太平洋暖池上方的对流层顶过渡层（TTL）的传输，科罗拉多大学博尔德分校的研究人员试图测量一些痕量卤素化合物的柱丰度，例如，在北方半球冬季，含有这些活性气体的对流层空气团可能优先被强热带对流高压输送到太平洋暖池区上空的TTL平流层低层。在这里，它们可能会影响平流层下部的化学，包括臭氧化学。对流层上部独特的低臭氧环境预计会产生非常少量的OH自由基，这预计会增加活性气体的寿命，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有机化合物寿命的延长可对平流层卤素收支产生重大影响。在设计CNOST实验的时间时，利用了与计划在同一时间和地理位置进行的两项国际空中研究的合作。这两个项目分别是NASA EV1项目ATTREX（热带对流层顶空中实验）和欧洲CAST（热带地区协调空中研究）。借助互补的仪器有效载荷，NSF GV，NASA Global Hawk和UK BAE 146的协调飞行将对热带西太平洋从表面到19公里的整个大气柱进行前所未有的检查。

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.