Atmospheric DMS and its role in new aerosol formation

二甲基硫氧化作用及其在产生新的气溶胶方面的作用有可能影响云的形成、持久性和持久性，这是气候研究的一个关键领域。 在北极和高纬度地区尤其如此，因为由于辐射强迫，最终产生大气DMS的表层海洋预计将经历比赤道更大的温度变化。 由于表层水温度的变化，海洋表层沃茨中二甲硫醚的梯度较高，一般预计会增加大气中二甲硫醚的混合比例，但海气交换的动态也是需要考虑的因素。 DMS的海气交换通常随海面粗糙度增加而增加，并表示为风速和海面温度的经验函数。 然而，据推测，与粗糙度无关的海洋表面特征促进了参与北极新气溶胶形成的化合物的海-气交换（Leck和Bigg，2005年）。 许多研究使用地表沃茨中的DMS测量值来估计DMS通量，并使用甲磺酸（MSA）与生物源硫酸盐的固定分支比来评估DMS气溶胶硫酸盐形成对云凝结核（CCN）的影响。 新的研究表明，这种估计可能严重低估了海洋到空气的DMS通量，和/或形成二氧化硫和硫酸盐的DMS氧化途径在中高纬度地区被低估，特别是在春季和夏季。 在这项研究中，硫酸盐气溶胶，二氧化硫和MSA，DMS氧化的产物的同位素特征将被用来评估区域尺度的DMS通量和DMS氧化途径在北极和北太平洋。 将通过一系列合作和独立的实地研究来评估二甲硫醚氧化的趋势，以便对二甲硫醚的寿命、其氧化途径及其形成新的气溶胶硫酸盐的潜力作出定量估计。

Dimethylsulphide (DMS) oxidation and its role in generating new aerosols that have the potential to influence cloud formation, persistence and albedo is a key area of study for climate research. This is particularly true in the Arctic and at high latitudes as the surface oceans that ultimately generate atmospheric DMS are expected to experience more temperature variation than at the equator due to radiative forcing. Higher DMS gradients in ocean surface waters as a result of changing in surface water temperatures are generally expected to increase DMS mixing ratios in the atmosphere but the dynamics of sea-air exchange are also factors that need to be considered. Sea-air exchange of DMS typically increases with sea surface roughness and is expressed as an empirical function of wind speed and sea surface temperature. However, ocean surface characteristics not related to roughness are postulated to promote sea-air exchange for compounds participating in new aerosol formation in the Arctic (Leck and Bigg, 2005). Many studies use DMS measurements in surface waters to estimate DMS flux and a fixed branching ratio for methanesulphonic acid (MSA) to biogenic sulphate to assess the impact of DMS aerosol sulphate formation on cloud condensation nuclei (CCN). New research shows such estimates may grossly under-represent sea to air DMS flux, and/or the DMS oxidation pathways forming sulphur dioxide and sulphate are underestimated at mid to high latitudes particularly during spring and summer. In this study, the isotope characteristics of sulphate aerosols, sulphur dioxide, and MSA, products of DMS oxidation will be used to assess regional scale DMS flux and DMS oxidation pathways in the Arctic and over the North Pacific. Trends in DMS oxidation will be assessed through a series of collaborative and independent field studies to provide quantitative estimates of DMS lifetime, its oxidation pathways, and its potential for forming new aerosol sulphate.