Waves, Aerosol and Gas Exchange Study (WAGES)

人们普遍认为，人类活动正在导致全球气候的变化;然而，由于气候系统的复杂性和所涉及的相互作用过程的数量，这些变化的程度远不能确定。一个核心过程是入射的太阳（短波）辐射和出射的红外（长波）辐射与大气，特别是云的相互作用。由于云的大小、位置和类型的变化，以及反射率等属性随云滴或冰晶浓度和大小分布的变化而发生的强烈变化，云在辐射平衡中存在很大的可变性和不确定性。海洋层积云（广泛的低层云层）起着主要作用。其云滴的大小和数量在很大程度上取决于可供云滴形成的气溶胶粒子的数量。海盐气溶胶是这种凝结核的主要来源。海盐气溶胶的产生是通过气泡破裂产生的水滴蒸发和被风从浪顶撕裂的喷雾而发生的。所产生的液滴的大小和数量，因此产生的气溶胶，随着不同的条件，如风速，波浪状态，波浪破碎等变化很大，为了准确地代表海洋云，因此得到正确的辐射平衡在气候模式中，我们必须首先确定有多少气溶胶和什么大小，在任何给定的条件下产生。这方面存在很大的不确定性（系数为10），特别是对气候过程最重要的最小气溶胶。该项目将测量在地表附近产生并向上输送到大气中的不同大小的气溶胶量，沿着各种不同条件下的风速、波浪大小和白顶。这些结果将提高我们对气溶胶生成的理解，并最终提高云在气候模型中的表现方式。模拟未来气候的另一个主要不确定因素是二氧化碳在大气和海洋之间转移的速度。二氧化碳吸收红外辐射;大气中二氧化碳的增加意味着更多的红外辐射被吸收，导致大气变暖。虽然二氧化碳被整个海洋吸收，但在不同的时间和地点，二氧化碳在大气和海洋之间的转移可以发生在任何一个方向上，这取决于空气和水中气体的局部浓度。传输速率还取决于风速、海况、波浪破碎等。与气溶胶产生一样，传输速率如何随不同条件变化存在很大的不确定性（在某些条件下约为两倍）。将利用对大气和海洋之间二氧化碳转移的直接测量，沿着对气象和波浪条件的直接测量，来减少二氧化碳转移参数化的不确定性。这反过来又可以改进长期气候模型。为了弄清影响气体和气溶胶通量的所有不同参数的影响，我们需要大量的数据。为了实现这一目标，我们将在世界上最后一艘气象船上使用自动测量系统，该船全年都在经历各种风浪条件的地区航行。我们将保持三年的测量。此外，我们将进行三次为期四周的载人巡航，每次我们将部署一个浮标，对波浪破碎进行详细测量，并将从风筝上放飞摄像机，以获得连续几个小时或更长时间的白浪数据。这些数据将使我们能够非常详细地研究驱动通量的过程，它们也将用于验证来自自主波浪和白顶系统的不太详细的数据，这些系统将连续测量整整三年。

IIt is widely accepted that the activities of mankind are leading to changes in global climate; however, the extent of those changes is far from certain due to the complexity of the climate system and the number of interacting processes involved. A central process is the interaction of incoming solar (shortwave) radiation, and outgoing infra-red (longwave) radiation with the atmosphere and in particular with clouds. Clouds present a large source of variability and uncertainty in the radiative balance due to the variation in size, location, and type of cloud, and also to the strong variation in properties such as reflectivity with changes in the concentration and size distribution of cloud droplets or ice crystals. Marine stratocumulus clouds (extensive sheets of low level clouds) play a major role. The size and number of their cloud droplets depends strongly on the number of aerosol particles available for droplets to form on. Sea-salt aerosol are a major source of such condensation nuclei. The generation of sea-salt aerosol occurs through evaporation of water droplets generated by bubble bursting and spray torn from wave tops by the wind. The size and number of droplets produced, and hence of the aerosol produced, varies greatly with different conditions such as wind speed, wave state, wave breaking, etc. In order to accurately represent marine clouds, and so get the radiation balance correct in climate models, we must first determine how much aerosol and of what size, is generated under any given conditions. There is much uncertainty in this (a factor of 10), particularly for the smallest aerosols which are the most important for climate processes. This project will measure the amount of aerosol at different sizes generated near the surface and transported upwards into the atmosphere, along with the wind speed, wave size and white-capping under a wide range of different conditions. The results will improve our understanding of aerosol generation, and ultimately the way in which clouds are represented within climate models. Another major uncertainty in modelling the future climate is the rate at which CO2 is transferred between the atmosphere and the oceans. CO2 absorbs infra-red radiation; an increase in CO2 in the atmosphere means more infra-red radiation is absorbed, causing a warming of the atmosphere. Although CO2 is absorbed by the oceans as a whole, at different times and places the transfer of CO2 between the atmosphere and ocean can occur in either direction depending upon the local concentrations of the gas in the air and water. The rate of the transfer also depends on the wind speed, sea-state, wave breaking etc. As with aerosol production, there are large uncertainties (about a factor of two in some conditions) in how the rate of transfer varies with different conditions. Direct measurements of the transfer of CO2 between the atmosphere and ocean, along with those of the meteorological and wave conditions, will be used to reduce the uncertainty in the parameterization of CO2 transfer. This will in turn allow improvements to long term climate models. To untangle the influence of all the different parameters that affect gas and aerosol fluxes we need a great deal of data. To obtain this we will use automatic measuring systems on the world's last weather ship which stays at sea all year round in a region which experiences a wide range of wind and wave conditions. We will maintain the measurements for three years. In addition we will have three manned cruises of 4 weeks each where we will deploy a buoy to make detailed measurements of wave breaking and will also fly a video camera from a kite to obtain continuous whitecap data for periods of a few hours or more. These data will allow us to study the process that drive the fluxes in great detail, and they will also be used to verify the less detailed data from the autonomous wave and whitecap systems which will measure continuously for the whole three years.