DIMETHYL SULFIDE CYCLING IN OPEN LEADS DURING THE ARCTIC OCEAN EXPEDITION 2001

全球气候与海冰变化、公海生物地球化学循环和环流、大气辐射和北冰洋云层密切相关。气-海-冰相互作用过程的不确定性导致不同全球气候模式模拟的北极和全球气候之间存在很大差异。特别是，浮冰中又长又窄的通道（几米到几百米宽，几公里长）对大气和北冰洋新气溶胶颗粒形成的影响，必须在气候模型中更准确地表现出来，以允许它们之间可能的反馈。瑞典极地研究秘书处向研究界提供了一个独特的平台（破冰船奥登号），作为2001年第三次夏季北极考察的一部分，题为“遥远北冰洋上空空气中颗粒的来源及其气候相关性”。这一努力将有助于对气候和环境敏感地区从海冰/空气界面到云顶边界层的化学过程和相关过程进行协调一致的研究。国际项目被设计为一个集成的包，包括现场实验阶段和紧密耦合的建模工作。该计划的总体目标是确定和量化生物、化学、物理和气象过程的作用，这些过程控制着与北极地区辐射强迫和气候有关的气溶胶的形成、演变和特性。国际计划的另一个目标是将结果纳入区域和全球气候模式，并提高气溶胶粒子对气候强迫计算的总体准确性。选择北冰洋中部作为试图提供关于气溶胶对气候变化作用的更好信息的首选地点，是基于其气候敏感性，考虑到北冰洋中部海冰在控制表面质量和能量通量方面的重要性，现有数据库相对较少，以及在很少受到大陆或人为源干扰的情况下跟踪整个气溶胶-云-辐射系统的可能性。目前，人们对浮冰的变薄和缩小的范围给予了极大的关注，这可能会增加铅的产生。铅促进了热量和物质的交换，将大气与北冰洋连接起来。该提案的重点是夏季，此时融化最大，铅最普遍。这个项目将专门解决“在冰和它旁边或下面的水柱中存在什么生物来源的化合物，这些化合物可能与空气中颗粒的产生有关？”为此，该项目将量化作为潜在气溶胶前体的DMS、DMSP和s -氨基酸在开放引线表面海水中的丰度和产量，并确定开放引线的生物含量以及水中的化学物质和颗粒（即POC、PON、POS、叶绿素a、微型浮游生物组成）。在适当和可能的情况下，这些参数也将在其他研究人员收集的冰和表面膜样本中进行测量。其他欧洲研究人员将研究海洋颗粒及其衍生产品如何在空气中传播，它们是否会导致新的颗粒在大气中形成或生长，以及在什么情况下。

Global climate is intimately connected to variability in sea ice, open ocean biogeochemical cycling and circulation, atmospheric radiation, and clouds over the Arctic Ocean. Uncertainty in the formulation of interactive air-sea-ice processes results in large differences between the arctic, and global, climates simulated by different global climate models. In particular, the effects of long, narrow channels (meters to hundreds of meters wide and kilometers long) in pack ice, also called leads, upon the atmosphere and the formation of new aerosol particles in the Arctic Ocean must be more accurately represented in climate models to allow possible feedbacks between them.The Swedish Polar Research Secretariat has presented the research community with a unique platform (Icebreaker Oden) as part of its third expedition to the summer Arctic in 2001 entitled "Sources of airborne particles over the remote Arctic Ocean and their climatic relevance". This effort will allow a concerted study of chemical and related processes from the sea-ice/air interface to the cloud-topped boundary layer in a climatically and environmentally sensitive region. The international program is designed as an integrated package, which includes both a field experimental phase and a closely coupled modeling effort. The overall aim of the program is to identify and quantify the role of the biological, chemical, physical and meteorological processes that control the formation, evolution, and properties of the aerosol relevant to radiative forcing and climate in the Arctic region. A further objective of the international program is to incorporate the results in both regional and global-climate models and to improve the overall accuracy in the calculation of climate forcing by aerosol particles.Selection of the central Arctic Ocean as the preferred site for an attempt to provide better information on the role of aerosols on climatic change is based on its climatic sensitivity given the importance of its sea ice in controlling mass and energy fluxes at the surface, the relatively sparse existing databases and the possibility of following the entire aerosol-cloud-radiation system with very little interference from continental or anthropogenic sources.Currently, a great deal of attention is being given to the thinning and decreased extension of pack ice, perhaps increasing the generation of leads. Leads facilitate the exchange of both heat and materials, coupling the atmosphere with the Arctic Ocean.The focus of this proposal is on the summer season when melt is maximal and leads are most prevalent . This project will specifically address the question of "What compounds of biological origin are present in the ice and in the water column next to or below it, and that may be involved in the production of airborne particles?" To this effect, the project will quantify the abundance and production of DMS, DMSP, and S-amino acids as potential aerosol precursors in surface seawater in open leads and also determine the biological content of the open leads and the chemicals and particles (i.e., POC, PON, POS, chlorophyll a, microplankton composition) in the water. These parameters will also be measured, when pertinent and possible, in ice and surface film samples collected by other investigators. Other European investigators will address issues concerning how the marine particles and derived products become airborne, whether they lead to new particle formation or growth in the atmosphere and under what circumstances.