Ultracompact laser ceilometer for boundary layer and cloud height retrievals; 20(c)

The advent of sensor networks to gather atmospheric data for weather and climate prediction on large spatial and temporal scales is crucial to the advancement of our understanding of many different important processes that make up such predictive models. A prime example is the height of the atmospheric boundary layer, which is used to parameterize boundary layer transport in numerical weather prediction models and boundary layer effects related to fluxes and concentrations of both trace gases and aerosols in inversion models. Increased knowledge of the boundary layer structure, and the diurnal evolution of its height, is driving the desire to add the capability to monitor boundary layer height to existing and planned networks, especially to aid in regional flux monitoring efforts. General statement of how this problem is being addressed. The overall objective of the Phase I project is to demonstrate the feasibility of a highly compact, automated, low power ceilometer to make retrievals of cloud base and boundary layer heights from remote unattended sites. The ceilometer is based on a fiber laser lidar design and packaged using state-of-the-art techniques for environmental stability. The feasibility will be evaluated through signal modeling, engineering design, and basic laboratory experiments. What is to be done in Phase I? In the Phase I program, a design will be developed for a compact, automated laser ceilometer that can retrieve both cloud base heights as well as the height of the atmospheric boundary layer and that will be deployable year round at AmeriFlux network tower sites. Laboratory experiments will demonstrate the feasibility of the ceilometer design. In the Phase II program, an engineering prototype sensor will be fabricated, tested, and field demonstrated at several AmeriFlux network sites. Commercial Applications and Other Benefits. The proposed ultracompact laser ceilometer will enable measurements of boundary layer and cloud base heights on a wider scale and at higher frequencies than are possible now. The proposed compact ceilometer will enable measurements of boundary layer and cloud base heights from towers in the AmeriFlux network on broad spatial and temporal scales. Such measurements are fundamental to improving our understanding of the complex couplings between the surface and lower atmosphere and will ultimately help to evolve models used in both weather forecasting and climate change prediction. Specifically it would aid in the refinement and development of regional CO2 flux estimates which would benefit goals of both the Terrestrial Ecosystem Science and Atmospheric System Research programs. The basic sensor will be adaptable to deployment in a variety of national weather networks, such as the Automated Surface Observing Systems network, where sensor robustness and size are critical to performance.