Infra-red gas analyzer

点击翻译按钮获取中文摘要

I request funds to purchase a LICOR 7000 closed path differential infra-red gas analyzer (LI-7000), an LI-610 dewpoint calibrator, and a Campbell Scientific data logger (CR-3000). These instruments will be used in a project whose aim is to measure the relative effectiveness of turbulent eddies in transporting momentum, water vapour and carbon dioxide to and from the surface. The mean rates of transport of these properties are called "fluxes," and corresponding to the fluxes there are mean vertical gradients in the associated properties - for example, during daytime over moist ground the mean water vapour flux is normally directed upward to the drier air aloft, thus, there is a vertical gradient in mean humidity. Present day weather and climate prediction models, as well as many other types of environmental model, require a specification of the "mixing" (or "exchange") coefficients K, Kw, Kc for (respectively) momentum, vapour and carbon dioxide. Unfortunately however, these values are not well known. In many studies, and notwithstanding existing evidence to the contrary, it is assumed ratios of these properties are (a) independent of the state of the atmosphere (i.e. universal); (b) independent of position; and (c) equal to 1.0.