Waves, Aerosol and Gas Exchange Study (WAGES)

人们普遍认为，人类的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涉及的相互作用过程的数量，这些变化的程度远不确定。一个中心过程是传入的太阳(短波)辐射和传出的红外线(长波)辐射与大气，特别是与云的相互作用。由于云的大小、位置和类型的不同，以及反射率等性质随着云滴或冰晶的浓度和大小分布的变化而发生的强烈变化，云在辐射平衡中表现出很大的变异性和不确定性。海洋层积云(大片低层云)起着主要作用。它们的云滴的大小和数量在很大程度上取决于可供水滴形成的气溶胶颗粒的数量。海盐气溶胶是这种凝聚核的主要来源。海盐气溶胶的产生是通过气泡破裂产生的水滴和被风从波顶上撕裂的水滴蒸发而产生的。产生的液滴的大小和数量以及由此产生的气溶胶的大小和数量随着风速、波浪状态、波浪破碎等不同条件而变化很大。为了准确地表示海洋云，从而在气候模式中正确地进行辐射平衡，我们必须首先确定在任何给定的条件下产生多少气溶胶以及产生的气溶胶的大小。这一点有很大的不确定性(系数为10)，特别是对于对气候过程最重要的最小气溶胶来说。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的数量，以及在各种不同条件下的风速、波浪大小和白帽。这些结果将提高我们对气溶胶产生的理解，并最终改善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性是二氧化碳在大气和海洋之间的转移速度。二氧化碳吸收红外线辐射；大气中二氧化碳的增加意味着吸收更多的红外线辐射，导致大气变暖。尽管二氧化碳作为一个整体被海洋吸收，但在不同的时间和地点，大气和海洋之间的二氧化碳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。转移率还取决于风速、海况、海浪破碎等。与气溶胶生产一样，转移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2倍)。将使用大气和海洋之间二氧化碳转移的直接测量，以及气象和波浪条件的测量，以减少二氧化碳转移参数的不确定性。这反过来将允许改进长期气候模型。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。为了实现这一点，我们将在世界上最后一艘气象船上使用自动测量系统，这艘船常年在海上航行，该地区经历了广泛的风浪条件。我们将把测量结果保留三年。此外，我们将有三次载人巡航，每次为期4周，我们将部署一个浮标来详细测量海浪破碎情况，还将从风筝上放飞摄像机，以获得持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，它们也将被用来验证来自自治波和白帽系统的不太详细的数据，这些系统将在整个三年内连续测量。

It 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.