01.14.19

Observing Clouds in Four Dimensions

Six cameras are revolutionizing observations of shallow cumulus clouds.

Click to enlarge photo. Enlarge Photo
Observing Clouds in Four Dimensions

Shallow cumulus clouds are big players in regulating the planet’s temperature. A new system gives researchers a 3-D view of these clouds and will help them test ideas about how such clouds act (click here.mp4 file (4.0MB) to see an animation).

The Science

While easily seen by people, the cotton-ball clouds (called shallow cumulus clouds) that drift overhead on partly cloudy days are hard for radars and many other instruments to observe and, therefore, hard to model and predict. Scientists situated six digital cameras in pairs at a distance of 6 kilometers (nearly 4 miles) from the Department of Energy’s Atmospheric Radiation Measurement user facility site in Oklahoma with a spacing of 500 meters (a third of a mile) between cameras in a pair. These pairs of cameras provide stereoscopic views of shallow clouds from all sides. When scientists combine the data, they get a complete 3-D view of how the clouds change every 20 seconds. This ring of cameras makes it possible to observe these clouds in greater detail than ever before.

The Impact

Because they are close to the Earth’s surface and are very bright, these puffball clouds have a cooling effect. Even small changes to their abundance as the planet warms could substantially ameliorate or exacerbate warming. These high-resolution observations will allow scientists to test theories regarding the behavior of these important clouds.

Summary

Shallow cumulus clouds play a large role in Earth's current energy balance, and their response to global warming makes a large and uncertain contribution to Earth's climate sensitivity. To develop accurate theories and parameterizations of shallow cloud cover, scientists need measurements of clouds' horizontal dimensions, their elevations, their depths, the rate at which they’re created, the rate at which they dissipate, and how all of these factors vary with changes to the large-scale environment. Only observations that are high-resolution relative to individual clouds in all four dimensions (space and time) can provide these needed data.

Toward this end, researchers installed a ring of cameras around the Southern Great Plains Atmospheric Radiation Measurement site in Oklahoma. Six digital cameras are situated in pairs at a distance of 6 kilometers from the site and with a spacing of 500 meters between cameras in a pair. These pairs provide stereoscopic views of shallow clouds from all sides; when scientists combine the data, they get a complete stereo reconstruction. The result, called the Clouds Optically Gridded by Stereo product, is a 4-D grid of cloudiness covering a cube measuring 6 kilometers by 6 kilometers by 6 kilometers at a spatial resolution of 50 meters and a temporal resolution of 20 seconds. This provides an unprecedented set of data on the sizes, lifetimes, and lifecycles of shallow clouds.

Contact

Program Managers
Shaima Nasiri
Department of Energy, Office of Science, Biological and Environmental Research, Atmospheric System Research
Shaima.Nasiri@science.doe.gov

Sally McFarlane
Department of Energy, Office of Science, Biological and Environmental Research, Atmospheric Radiation Measurement (ARM) User Facility
Sally.McFarlane@science.doe.gov

Dorothy Koch
Department of Energy, Office of Science, Biological and Environmental Research, Earth and Environmental System Modeling
Dorothy.koch@science.doe.gov

Principal Investigator
David Romps
Lawrence Berkeley National Laboratory and University of California, Berkeley
dromps@lbl.gov; (510) 486-7175

Funding

This work was supported by the Department of Energy’s Atmospheric Radiation Measurement, Atmospheric System Research, and Climate Model Development and Validation programs through the Office of Science’s Biological and Environmental Research.

Publications

D.M. Romps and R. Oktem, “Observing clouds in 4D with multi-view stereo photogrammetry.” Bulletin of the American Meteorological Society (2018). [DOI: 10.1175/BAMS-D-18-0029.1]

Related Links

Atmospheric Radiation Measurement websiteExternal link

University of California website: Observing clouds in 4D with multi-view stereo photogrammetryExternal link

Highlight Categories

Program: BER, CESD

Performer/Facility: University, SC User Facilities, BER User Facilities, ARM

Last modified: 1/14/2019 1:51:50 PM