Detailed Studies on Physics and Chemistry of Mountain Cloud Water

Basic data for this project

Description

Clouds play a complicated role in climate change as they may inforce both positive and negative radiation forcings. One of the most important characteristics driving their radiative properties is their droplet size distribution (DSD). Surprizingly, only little in known about the temporal and spatial variation of DSD's and the processes behind. The work here aims at contributing fundamental research on cloud microphysics, i.e. the variability of DSD, the liquid water content (LWC), the water vapor content, and eventually of the relative humidity (rH) in clouds. A field study on top of Mt. Lulin, over 2800 m above sea level, is planned. The site is often immersed in clouds that are therefore experimentally accessible. It is planned to employ a newly developed cloud droplet separator to measure the mentioned properties with 10 Hz time resolution, corresponding to about 0.5 m spatial resolution. Novel data with so far un-achieved resolution and precision will be collected, cloud microphysics will be described in an unprecedented way. Further, we propose to study the chemical composition of cloud water in much more detail than so far. Although the resolution will be much less than for the physical measurements, chemical composition of cloud warter (ions, Hg) will add much detail to the knowledge available so far. What is the role of chemistry in development of the DSD? Mercury will be used as a specific tracer for anthropogenic contribution to cloud water chemistry at this rather pristine and remote site.