What controls marine boundary layer aerosols over the Atlantic Ocean?

是什么控制着大西洋上空的海洋边界层气溶胶？

• 批准号: 326874835
• 负责人: Dr. Birgit Wehner
• 金额: --
• 依托单位: Leibniz-Institut für Troposphärenforschung e.V. (TROPOS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/326874835?language=en
• 关键词: What; controls; marine; boundary; layer

Aerosol particles play an important role for the regional and global climate. Therefore, a network of measurement sites has been established worldwide, but only a small fraction of them is capturing the marine boundary layer (MBL) while approximately 70% of the Earth´s surface is covered with water. The main focus of this project is to improve the knowledge of sources and exchange processes of aerosol particles in the MBL joining a measurement campaign over the Azores in the northeastern Atlantic Ocean where the influence of local anthropogenic sources is negligible. The main hypothesis of the project is that long-range transport from North America as well as new particle formation in the free troposphere (FT) and at cloud edges followed by vertical transport contribute significantly to the aerosol budget in the MBL. The knowledge of sources and sinks of aerosol particles in combination with vertical exchange between FT and MBL is a prerequisite to predict aerosol particle number concentrations in the lowest regions of MBL and its influence on the formation of clouds. These processes are not sufficiently quantified over the ocean up to now. To verify the hypothesis stated above vertical exchange processes and particle sources over the Azores will be quantified with high spatial resolution using a helicopter-borne platform developed at TROPOS. Here, aerosol particle number concentration and vertical wind speed will be measured with a temporal resolution allowing the direct estimate of the vertical turbulent flux of aerosol particles in different heights for the first time. The required fast measurements of particle number concentrations with at least 10 Hz are possible by utilizing a Fast Condensation Particle Counter developed at TROPOS, which has been applied successfully within the framework of an earlier DFG project. Using this instrument it will also be possible to check whether new particle formation at cloud edges occurs regularly in this region as observed at trade wind cumuli before on scales of a few decameters. In addition, aerosol particle number size distributions and particle absorption at three different wavelengths will be determined. These data will be used to conclude sources and origin of the investigated aerosol particles. Measurement flights performed by the helicopter are limited in time and provide therefore a "snapshot" of the atmosphere. Thus, additional continuous measurements of aerosol particle number size distributions will be installed at two ground-based sites. One of them is located few meters above sea level and the second one in 2200 m asl in the FT. These continuous measurements will be used to study connections and exchange processes between MBL and FT over the whole measurement period of one month. The data set will help to estimate possible influences of global warming on the local climate and potential feedback effects on the influence of aerosol particles on cloud formation and properties in this region.

气溶胶粒子对区域和全球气候起着重要作用。因此，在世界范围内建立了一个测量站网络，但其中只有一小部分捕获了海洋边界层（MBL），而地球表面约70%被水覆盖。该项目的主要重点是提高MBL对气溶胶颗粒来源和交换过程的认识，加入大西洋东北部亚速尔群岛的测量活动，当地人为来源的影响可以忽略不计。该项目的主要假设是，来自北美的远程输送以及自由对流层和云边缘的新粒子形成，以及随后的垂直输送对MBL的气溶胶预算有重要贡献。了解气溶胶粒子的源汇，结合ftm和MBL之间的垂直交换，是预测MBL最低区域气溶胶粒子数浓度及其对云形成影响的先决条件。到目前为止，这些过程在海洋上还没有得到充分的量化。为了验证上述假设，将使用TROPOS开发的直升机载平台对亚速尔群岛上空的垂直交换过程和粒子源进行高空间分辨率的量化。在这里，气溶胶粒子数、浓度和垂直风速将以时间分辨率进行测量，从而首次直接估计不同高度气溶胶粒子的垂直湍流通量。通过使用TROPOS开发的快速冷凝粒子计数器，可以以至少10 Hz的速度快速测量粒子数浓度，该计数器已在早期DFG项目的框架内成功应用。使用这台仪器，还可以检查云边缘的新粒子形成是否在这个地区有规律地发生，就像以前在几十米尺度上观察到的信风积云一样。此外，气溶胶粒子数、大小分布和粒子在三种不同波长的吸收将被确定。这些数据将用于确定所研究的气溶胶颗粒的来源和来源。由直升机进行的测量飞行在时间上是有限的，因此只能提供大气的“快照”。因此，将在两个地面站点安装额外的气溶胶颗粒数大小分布的连续测量装置。其中一个位于海拔几米的地方，另一个位于海拔2200米的地方。这些连续的测量将用于研究MBL和FT在一个月的整个测量期间的连接和交换过程。该数据集将有助于估计全球变暖对当地气候的可能影响，以及气溶胶颗粒对该地区云的形成和性质影响的潜在反馈效应。