Atmospheric river

Atmospheric rivers (English atmospheric river, AR) is the name for 400 to 600 km wide and up to several thousand km long straps moisture -saturated air from the equatorial regions of approximately 1 to 2.5 km altitude. In them, most of the moisture transport takes place in the atmosphere outside of the tropics. Due to the origin in the tropical marine region, for example in the central Pacific and Hawaii so that such flows on the west coast of the United States of America is already longer than Pineapple Express (English Pineapple Express ) is known. Such Pineapple Express usually takes three to five days heavy rain or snow. In extreme cases, these bands can be much longer and extend over an entire ocean. The funded amount of water in such a band may, according to the National Oceanic and Atmospheric Administration ( NOAAA ) 7.5 - amounted to 15 times the Mississippi at the mouth ..

• 3.1 Due to atmospheric rivers caused extreme events

Discovery history

In the 1970 " conveyor belts of moisture " were discovered in the atmosphere. Only in 1998 discovered Yong Zhu and Reginald E. Newell of the Massachusetts Institute of Technology through the analysis of data of the European Centre for Medium-Range Weather Forecasts in Reading much narrower bands with extremely high moisture content. They named the phenomenon of atmospheric rivers. At any given time are about five such atmospheric fluxes in the atmosphere, transporting approximately 90 % of the moisture from the equatorial region in the mid-latitudes. Annually meet at least nine such rivers as the California coastline, and carry it 30 to 50 percent of the precipitate on the American east coast. Atmospheric flows are also other seas as the Pacific.

Research

Since the discovery of atmospheric rivers, the streams are monitored by radar and weather satellites. Models for moisture transport in the atmosphere now contain the data and model accordingly.

Great Britain

Britain was affected in the years between 1983 to 2013 on average 9-11 atmospheric rivers per year. 2013 reported the English Institute of Physics based on research by the University of Reading and the University of Iowa, the study of heavy rainfall due to atmospheric rivers. For this purpose, atmospheric rivers 1980-2005 were recalculated in five different climate models to determine whether these models corresponded to the course of the actual events. After these models had all been found suitable, future events were calculated on the basis of two scenarios. All five models were among the basic assumptions 2074-2099 approximately a doubling of atmospheric rivers affecting the UK compared to the period from 1980 until 2005.

Effects of atmospheric rivers

Most atmospheric rivers are responsible for the normal, typical seasonal rainfall in different regions. They contribute, for example, at 30 to 50% of the normal rainfall on the U.S. West Coast. Only very strong and long-lasting rivers cause flooding events.

Due to atmospheric rivers caused extreme events

Atmospheric rivers are regarded as causes of various extreme events. The Earth System Research Laboratory of the NOAAA limited to incidents which are the subject -received in Fachmagazinenen publications, including:

In extreme cases, such as occur approximately every 200 years, the rains but are not limited to a few days but at last for weeks. The combination of two such incidents, one Pineapple Express in 1969 and 1986 created a research group on behalf of the United States Geological Survey ( USGA), the Arkstorm scenario in which an atmospheric river brings 23 days of rain in California and estimated damages in the range of 700 billion cause. USD. Reports from 1861/62 talk 45 days of continuous, torrential rains.