Arkstorm

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An Arkstorm , correct ARkStorm for Atmospheric River kilo Storm (English Atmospheric River 1000 Storm) is the name for a weather scenario of the United States Geological Survey , which investigates severe winter storms with heavy rainfall in California . The scenario was created to test the disaster control measures and is a link in a chain of such scenarios for possible natural disasters such as earthquakes (ShakeOut), tsunamis , forest fires , landslides and coastal erosion.

The basis for the phenomenon are similar rains to those that began on Christmas Eve 1861 and brought 45 days of uninterrupted rain ( Great Flood of 1862 ). Large parts of the Central Valley became impassable and Los Angeles became a muddy lake. Investigations of sediment on the river terraces of large rivers in California, however, show that the Great Flood of 1862 wasn't even the worst in California history.

Lithograph of K Street in Sacramento , California during the 1862 Flood

In the Arkstorm scenario, the measurement data from two weather conditions known as “ pineapple express ” in January 1969 and February 1986 were combined and simulated using computers. The calculated result was heavy rainfall for 23 days. The scenario does not generate the worst imaginable expression, so it is not a worst-case scenario . For California, the incidence of Arkstorms is estimated at one incident in 100 to 200 years.

Effects of the scenario

Areas threatened by a flood according to the ARkStorm scenario

According to the scenario, the Central Valley would be flooded over a length of around 500 km and a width of 20 km. The densely populated centers of Los Angeles , San Francisco , San Diego and Orange County would also be affected by severe flooding . The total cost of the hypothetical damage is estimated at over $ 700 billion. The scenario raised doubts as to whether the public administration would be able to handle this. It was considered whether substantial sums should be invested in disaster control measures or much larger sums in dealing with the consequences of such a scenario.

The scenario met with interest in the media and is now being investigated in other regions of the world. The meteorologist Andreas H. Fink from the University of Cologne believes that similar rainfall is also possible in Europe.

Meteorological basics

Arkstorms are caused by tropical air masses that are stably shifted in atmospheric rivers over several days in coastal regions. The amount of water present in the streams is given as 7 to 15 times that of the Mississippi . On the west coasts of the continents, if necessary, favored by mountain ranges, uphill rain can occur and rain heavily for several days. Reports from the winter of 1861/62 speak of 45 days of rain and thus make the scenario seem plausible. In addition, sediment samples from the Central Valley have historically proven similar occurrences. The geological findings from the Bay of San Francisco suggest further severe storms with floods in 212, 440, 603, 1029, 1418 and 1605.

The atmospheric rivers were only discovered in 1998 by Yong Zhu and Reginald Newell of the Massachusetts Institute of Technology through the analysis of data from the European Center for Medium-Range Weather Forecasts . According to this, atmospheric currents are responsible for shifting around 95 percent of the humidity in the direction of the poles. This can lead to heavy rain on the west coasts of the continents, for example in the UK or Spain in autumn 2009 .

Web links

Individual evidence

  1. ↑ a b c d e f g h i 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
  2. ↑ a b c d e f g Andreas Frey: Flood in the sun state. Frankfurter Allgemeine Zeitung from May 16, 2011
  3. ↑ Michael D. Dettinger, B. Lynn Ingram: The next deluge. In: Spectrum of Science 2013, Issue 4 . PDF, 1.2 MB. Page 74 ff.
  4. ↑ a b ARkStorm: California's Other 'Big One'. In: Science Daily of January 18, 2011
  5. ↑ a b c d Terra X from May 12, 2013 , Arkstorm also possible in Europe ; Interview with meteorologist and expert Prof. Dr. Andreas H. Fink on the weather phenomenon Arkstorm, which is also conceivable in Europe to a lesser extent due to climate change.
  6. ↑ a b c d e f Philip Bethge: Sea of ​​mud. In: Der Spiegel 6/2013 of February 4, 2013