Mission Possible: Estimating Cloud Area from Sky Images
A new method provides a previously unavailable data set that could help improve the representation of shifty shallow cumulus clouds in atmospheric models
Complex interactions between Earth's surface and the atmosphere, such as the exchange of water and energy, often involve clouds and the combination of their size and shape—or cloud equivalent diameters. When it comes to shallow cumuli—puffy, cotton ball-like clouds with rapidly evolving cloud equivalent diameters—available ground-based and satellite sensors fall short of capturing these changes at the level of detail required to assess and improve the representation of shallow cumuli in atmospheric models.
Researchers from the U.S. Department of Energy's (DOE) Pacific Northwest National Laboratory, Lewis & Clark College, and the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, Boulder, teamed up to develop a method for obtaining the required information on cloud equivalent diameter with high time resolution. They introduced a simple, computationally inexpensive method using low-cost, ground-based sky images.
The new method provides a previously unavailable data set for process studies of the convective boundary layer and for evaluation of shallow cumuli growth, maturation, and dissipation in cloud-resolving models. Because many atmospheric research sites worldwide deploy low-cost, ground-based sky imagers, the research team plans to apply the new method to existing and future studies at different locations.
Reference: J.M. Kleiss, E.A. Riley, C.N. Long, L.D. Riihimaki, L.K. Berg, V.R. Morris, E. Kassianov, "Cloud Area Distributions of Shallow Cumuli: A New Method for Ground-Based Images." Atmosphere 9(7), 258 (2018). [https://doi.org/10.3390/atmos9070258]
Published: August 27, 2018