Atmospheric river

Water vapor imagery of the eastern Pacific Ocean from the GOES 11 satellite, showing a large atmospheric river aimed across California in December 2010. This particularly intense storm system produced as much as 26 in (66 cm) of precipitation in California and up to 17 ft (520 cm) of snowfall in the Sierra Nevada from December 17–22, 2010.

Layered precipitable water imagery of a particularly strong atmospheric river stretching from the Caribbean to the United Kingdom on 5 December 2015, caused by Storm Desmond. A second atmospheric river, which originated from the Philippines, can be seen in the Pacific Ocean off the west coast of North America.

An atmospheric river is a narrow corridor or filament of concentrated moisture in the atmosphere. Atmospheric rivers consist of narrow bands of enhanced water vapor transport, typically along the boundaries between large areas of divergent surface air flow, including some frontal zones in association with extratropical cyclones that form over the oceans.

The term was originally coined by researchers Reginald Newell and Young Zhu of the Massachusetts Institute of Technology in the early 1990s, to reflect the narrowness of the moisture plumes involved. Atmospheric rivers are typically several thousand kilometers long and only a few hundred kilometers wide, and a single one can carry a greater flux of water than the Earth's largest river, the Amazon River. There are typically 3–5 of these narrow plumes present within a hemisphere at any given time.

Atmospheric rivers have a central role in the global water cycle. On any given day, atmospheric rivers account for over 90% of the global meridional (north-south) water vapor transport, yet they cover less than 10% of the Earth's circumference.

They also are the major cause of extreme precipitation events which cause severe flooding in many mid-latitude, westerly coastal regions of the world, including the West Coast of North America, western Europe, and the west coast of North Africa.

See also

• Pineapple Express, an atmospheric river which affects the West Coast of North America
• Tropical upper tropospheric trough, a band of moisture common in tropical regions
• ARkStorm, a hypothetical storm by the same name that could possibly affect California
• Great Flood of 1862 (massive flooding in US West)

External links

• NOAA Earth System Research Laboratory: Atmospheric River Information Page
• NOAA Earth System Research Laboratory: Atmospheric River Publications List
• NOAA Earth System Research Laboratory: Atmospheric Rivers (PDF brochure)
• NOAA News Online: NOAA Researchers Study Rivers of the Sky (2005)
• SSMI/AMSRE-derived Total Precipitable Water – Global — Animation showing current atmospheric rivers (University of Wisconsin CIMSS)
• GOES Eastern Pacific water vapor imagery — Naval Research Laboratory Monterey
• Worse floods ahead for UK as climate warms, say scientists