Atmospheric flow
Atmospheric rivers ( AR ) is the name for 400 to 600 km wide and up to several thousand km long bands of moisture-saturated air from the equatorial regions at an altitude of approx. 1 to 2.5 km. Most of the moisture transport in the atmosphere outside of the tropics takes place in them.
On the west coast of the United States of America such flows are already longer because of their origin from the tropical marine region, for example in the central Pacific and in Hawaii as Pineapple Express (Engl. Pineapple Express ) known. Such a pineapple express usually brings three to five days of heavy rain or snow .
In extreme cases, these bands can be much longer and span an entire ocean. According to the National Oceanic and Atmospheric Administration (NOAA), the amount of water pumped in such a band can be 7.5 to 15 times the average flow rate of the Mississippi at its mouth.
Discovery story
In the 1970s "conveyor belts of moisture" were discovered in the atmosphere. It was not until 1998 that Yong Zhu and Reginald E. Newell of the Massachusetts Institute of Technology discovered much narrower bands with extremely high moisture content by analyzing data from the European Center for Medium-Range Weather Forecasts in Reading . They named the phenomenon atmospheric rivers .
At any given time, there are around five such atmospheric rivers in the atmosphere, transporting around 90% of the humidity from the equatorial region to the mid-latitudes . Every year at least nine such rivers hit the California coast and transport 30 to 50 percent of the total precipitation that falls on the American west coast. Atmospheric rivers also arise over seas other than the Pacific.
research
Since the discovery of the atmospheric rivers, they have been monitored by radar and weather satellites . Models of moisture transport in the atmosphere now contain their data and model accordingly.
Great Britain
The UK was affected by an average of 9 to 11 atmospheric rivers per year between 1983 and 2013.
In 2013, based on research by the University of Reading and the University of Iowa , the English Institute of Physics reported the study of heavy rain as a result of atmospheric rivers. For this purpose, atmospheric flows between 1980 and 2005 were recalculated in five different climate models in order to determine the extent to which these models corresponded to the course of the actual events. After all models had proven to be suitable, future events were calculated on the basis of two scenarios. Under the basic assumptions, all five models showed an approximately doubling of atmospheric fluxes affecting Great Britain between 2074 and 2099 compared to the period from 1980 to 2005.
According to recent studies, eight out of ten extreme precipitation incidents in Europe between 1979 and 2011 could be traced back to atmospheric rivers.
Effects
Most atmospheric rivers are responsible for the normal seasonal rainfall in different regions. For example, they contribute 30 to 50% to the normal rainfall on the American west coast. Only very strong and persistent rivers lead to flooding events.
Extreme events caused by atmospheric rivers
Atmospheric rivers are considered to be the cause of various extreme events. The Earth System Research Laboratory of NOAAA limited to transactions for which there are in-received Fachmagazinenen publications, including:
| February 11-24, 1986 | Northern and Central California | Heavy rainfall with floods, 13 deaths, 50,000 people had to be evacuated. Damage around 400 million USD. |
| December 29, 1996 to January 4, 1997 | Northern California and Western Nevada | Heavy rainfall, which in places caused a century flood , 2 deaths and 120,000 people evacuated; Damage of USD 1.6 billion |
| February 2nd and 3rd, 1998 | Central California Coast and Santa Cruz Mountains | Heavy regional rainfall with flooding; the weather warning given 6 hours before the incident presumably saved lives. |
| February 16-18, 2004 | Northern California and the Russian River Basin | Heavy rainfall in the basin of the Russian River, which led to record floods for several days. |
| January 7-11, 2005 | Southern California | Heavy rains north and east of Los Angeles , 14 deaths and hundreds of evacuees; damages of USD 200 to 300 million |
| March 25-27, 2005 | Western Oregon and Western Washington State | Heavy rainfall that did not result in flooding due to the previous drought. |
| September 13-14, 2005 | Western Norway | Highest rainfall ever recorded on one day at the Bergen-Florida weather station, mudslides and 3 deaths. |
| December 29, 2005 to January 2, 2006 | Northern California | Heavy rainfall on the Russian River and Napa Valley ; Damage of $ 300 million. |
| November 6th to 7th, 2006 | Western Washington and Northern Oregon | Heavy rainfall results in damage valued at $ 50 million. |
| January 6th to 8th, 2009 | Western Washington | Heavy rain causes damage of US $ 125 million, and 30,000 people are forced to evacuate. |
| October 13-14, 2009 | Northern California and Central California | Heavy rainfall that did not result in flooding due to the previous weather conditions; Damage amount of 10 million USD. |
| November 17th to 19th, 2009 | Northern UK | Heavy rains lead to floods and claim human lives. |
| February 5-6, 2010 | Central Atlantic coast of the United States | The weather incident known as Snowmageddon in 2010, in which up to 1 m of snow fell over several countries, in record amounts in many places, and forced authorities to close, resulted in power outages across the board and caused considerable disruptions in the transport system. |
| January 2013 | Severe flooding in Australia as a result of cyclone Oswald |
In extreme cases, such as occur approximately every 200 years, the rainfall is not limited to a few days, but lasts for weeks. Merging two such incidents, a pineapple express from 1969 and 1986, a group of researchers commissioned the United States Geological Survey (USGA) created the Arkstorm scenario, in which an atmospheric river brings 23 days of rain to California and estimated damage in the range of 700 Billion USD. Reports from 1861/62 speak of 45 days of uninterrupted torrential rain.
Economic consequences
The insurance industry evaluates risks in order to provide its actuaries with the necessary data. In 2015, according to a magazine report, the Swiss insurance company Swiss Re rated atmospheric rivers as one of the 21 greatest risks of the coming years.
Individual evidence
- ↑ a b c d e f g Michael D. Dettinger and B. Lynn Ingram (2013) The Next Deluge , Spectrum of Science 2013/4 (PDF; 1.2 MB); Page 74 ff.
- ↑ a b c Larry O'Hanlon, Most of Europe's extreme rains caused by 'rivers' in the atmosphere ; from July 19, 2013; accessed on May 16, 2014.
- ↑ a b c Atmospheric River Information Page of the Earth System Research Laboratory (ESRL) of the National Oceanic & Atmospheric Administration (NOAA); accessed on January 30, 2014.
- ↑ a b c d website of the Earth System Research Laboratory of the National Oceanic and Atmospheric Administration, accessed on September 28, 2013
- ↑ a b Andreas Frey (2011) Flood in the Sun State , Frankfurter Allgemeine Zeitung, May 16, 2011
- ↑ a b c David Shukman, 'Rivers' in air could boost flooding ; BBC News and Science; July 25, 2013.
- ↑ a b c Yong Zhu and Reginald E. Newell (1998) A proposed algorithm for moisture fluxes from atmospheric rivers . Monthly Weather Review, 126, 725-735.
- ↑ Philip Bethge (February 4, 2013) Sea of Mud ; Der Spiegel 6/2013
- ↑ a b c Institute of Physics; Atmospheric rivers set to increase UK winter flooding , July 24, 2013.
- ↑ EnvironmentalResearchWeb; Atmospheric rivers set to increase UK winter flooding ( Memento of the original from February 1, 2014 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , 1 August 2013.
- ↑ a b c d e f g h i j k l List of extreme events triggered by atmospheric rivers, accessed on September 29, 2013
- ↑ University of Wisconsin CIMSS Satellite Blog; Atmospheric river of moisture targets Britain and Ireland , accessed January 30, 2014.
- ↑ Summary of the ArkStorm scenario of the US Geological Survey from: Keith Porter, Anne Wein, Charles Alpers, Allan Baez, Patrick Barnard, James Carter, Alessandra Corsi, James Costner, Dale Cox, Tapash Das, Michael Dettinger, James Done, Charles Eadie , Marcia Eymann, Justin Ferris, Prasad Gunturi, Mimi Hughes, Robert Jarrett, Laurie Johnson, Hanh Dam Le-Griffin, David Mitchell, Suzette Morman, Paul Neiman, Anna Olsen, Suzanne Perry, Geoffrey Plumlee, Martin Ralph, David Reynolds, Adam Rose, Kathleen Schaefer, Julie Serakos, William Siembieda, Jonathan Stock, David Strong, Ian Sue Wing, Alex Tang, Pete Thomas, Ken Topping, directed by Chris Wills and Lucile Jones; Project manager Dale Cox (201) Overview of the ARkStorm scenario: US Geological Survey Open-File Report 2010-1312 , 183 pages plus attachments
- ↑ The Biggest Future Risks for the Insurance Industry in the Insurance Journal of May 21, 2015; accessed on May 26, 2015.
