WGSC -- Pacific Coastal Fog Project

The Pacific Coastal Fog Project: Developing ecologically relevant fog datasets

(hover on image to see identifying features)

Figure Caption: The Landsat image of May 22, 1991 shows the marine stratus and stratocumulus cloud layer that moved into the San Francisco Bay-Delta and Monterey Bay. Several cloud patterns can be seen in this image: the eddy-like spiral to the west of the Golden Gate, the darker linear cloud feature that parallels the coast down to Monterey Bay, and fog funneling from Monterey Bay inland. Researchers are using synoptic meteorology, aerosol chemistry, cloud thermodynamics, microphysics, and physical oceanography to better understand the processes behind these patterns. This research will improve the representation of clouds in global circulation and climate models. 

Coastal marine fog is an important meteorological phenomenon for California.  A cloud—either stratus or stratocumulus—is called “fog” when it is low or touching the ground. Marine fog forms as a result of complex interactions between ocean evaporation, aerosols, atmospheric pressure, vertical air layering, onshore-offshore temperature gradients, and coastal mountain topography. The marine cloud layer provides moisture to the arid and semi-arid coast, especially in the warm summer months, as it moves from the ocean into coastal communities and ecosystems of California.

In 2010 researchers revealed that summertime fog hours had declined by 33% over the last century (Johnstone and Dawson 2010). Natural resource managers working to protect California’s coastal plant and animal communities in the face of a warming climate became alarmed.  Was the trend a result of climate change, long term global cycles, or statistical coincidence? Additional research was needed to understand fog dynamics over time and explore implications for the future. If the decline in coastal fog were to continue, many species and ecosystems would be significantly impacted. It became clear that maps were needed showing the location of the foggiest areas to help guide restoration and planting activities, however no easily accessible fog maps existed. Despite the easily accessible, nearly real-time satellite images of fog available from the National Weather Service, the image data formats are difficult to utilize and manipulate by most ecologists and planners.

To assist in gathering and making fog maps more accessible and usable to both professionals and the general public, the Pacific Coastal Fog Project was started in early 2012. The project was initiated and funded by the California Landscape Conservation Cooperative (CA LCC) and the U.S. Geological Survey’s Climate and Land-Use Change Mission Area, Land Change Science Program to create ecologically relevant fog datasets. The work intensified during the first International Pacific Coastal Fog workshop in April 2012 sponsored by the Gordon and Betty Moore Foundation. This workshop brought together a multidisciplinary group of scientists and natural resource managers to assess current understanding of coastal fog as a system of interacting ocean, air, and land surface processes. This systems view includes examination of the plants, animals, and humans impacted by fog and that, in turn, also impact fog. 


California Landscape Conservation Cooperative

More Information:

Johnstone, James A., and Todd E. Dawson. "Climatic context and ecological implications of summer fog decline in the coast redwood region." Proceedings of the National Academy of Sciences 107.10 (2010): 4533-4538.

Estuary News March 2014 Insert: Fog’s Fingerprint on Coastal Ecology by Jacoba Charles http://www.sfestuary.org/wp-content/uploads/2014/03/CALCC-Mar2014-v7x-web.pdf

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