Editing Numerical weather prediction (section)

== History ==
{{Main|History of numerical weather prediction}}
[[File:Two women operating ENIAC.gif|thumb|280px|The ENIAC main control panel at the [[Moore School of Electrical Engineering]] operated by [[Jean Bartik|Betty Jennings]] and [[Frances Spence|Frances Bilas]]]]
The [[history of numerical weather prediction]] began in the 1920s through the efforts of [[Lewis Fry Richardson]], who used procedures originally developed by [[Vilhelm Bjerknes]]<ref name="Lynch JCP"/> to produce by hand a six-hour forecast for the state of the atmosphere over two points in central Europe, taking at least six weeks to do so.<ref>{{cite journal |last1=Simmons |first1=A. J. |last2=Hollingsworth |first2=A. |date=2002 |title=Some aspects of the improvement in skill of numerical weather prediction |url=https://doi.org/10.1256/003590002321042135 |journal=Quarterly Journal of the Royal Meteorological Society |volume=128 |issue=580 |pages=647–677 | doi=10.1256/003590002321042135|bibcode=2002QJRMS.128..647S |s2cid=121625425 }}</ref><ref name="Lynch JCP">{{cite journal|last=[[Peter Lynch (meteorologist)|Lynch]]|first=Peter|title=The origins of computer weather prediction and climate modeling|journal=[[Journal of Computational Physics]]|date=March 2008|volume=227|issue=7|pages=3431–44|doi=10.1016/j.jcp.2007.02.034|bibcode=2008JCoPh.227.3431L|url=http://www.rsmas.miami.edu/personal/miskandarani/Courses/MPO662/Lynch,Peter/OriginsCompWF.JCP227.pdf|access-date=2010-12-23|url-status=dead|archive-url=https://web.archive.org/web/20100708191309/http://www.rsmas.miami.edu/personal/miskandarani/Courses/MPO662/Lynch,Peter/OriginsCompWF.JCP227.pdf|archive-date=2010-07-08}}</ref><ref name="Lynch Ch1">{{cite book|last=Lynch|first=Peter|title=The Emergence of Numerical Weather Prediction|url=https://archive.org/details/emergencenumeric00lync|url-access=limited|year=2006|publisher=[[Cambridge University Press]]|isbn=978-0-521-85729-1|pages=[https://archive.org/details/emergencenumeric00lync/page/n11 1]–27|chapter=Weather Prediction by Numerical Process}}</ref> It was not until the advent of the computer and [[computer simulation]]s that computation time was reduced to less than the forecast period itself. The [[ENIAC]] was used to create the first weather forecasts via computer in 1950, based on a highly simplified approximation to the atmospheric governing equations.<ref name="Charney 1950"/><ref>{{cite book|title=Storm Watchers|page=[https://archive.org/details/stormwatcherstur00cox_df1/page/208 208]|year=2002|author=Cox, John D.|publisher=John Wiley & Sons, Inc.|isbn=978-0-471-38108-2|url=https://archive.org/details/stormwatcherstur00cox_df1/page/208}}</ref> In 1954, [[Carl-Gustav Rossby]]'s group at the [[Swedish Meteorological and Hydrological Institute]] used the same model to produce the first operational forecast (i.e., a routine prediction for practical use).<ref name="Harper BAMS">{{cite journal|last=Harper|first=Kristine|author2=Uccellini, Louis W. |author3=Kalnay, Eugenia |author4=Carey, Kenneth |author5= Morone, Lauren |title=2007: 50th Anniversary of Operational Numerical Weather Prediction|journal=[[Bulletin of the American Meteorological Society]]|date=May 2007|volume=88|issue=5|pages=639–650|doi=10.1175/BAMS-88-5-639|bibcode=2007BAMS...88..639H|doi-access=free}}</ref> Operational numerical weather prediction in the United States began in 1955 under the Joint Numerical Weather Prediction Unit (JNWPU), a joint project by the [[U.S. Air Force]], [[U.S. Navy|Navy]] and [[U.S. Weather Bureau|Weather Bureau]].<ref>{{cite web|author=American Institute of Physics|date=2008-03-25|url=http://www.aip.org/history/sloan/gcm/ |title=Atmospheric General Circulation Modeling|access-date=2008-01-13 |archive-url = https://web.archive.org/web/20080325084036/http://www.aip.org/history/sloan/gcm/ |archive-date = 2008-03-25}}</ref> In 1956, [[Norm Phillips|Norman Phillips]] developed a mathematical model which could realistically depict monthly and seasonal patterns in the troposphere; this became the first successful [[climate model]].<ref name="Phillips">{{cite journal|last=Phillips|first=Norman A.|title=The general circulation of the atmosphere: a numerical experiment|journal=Quarterly Journal of the Royal Meteorological Society|date=April 1956|volume=82|issue=352|pages=123–154|doi=10.1002/qj.49708235202|bibcode=1956QJRMS..82..123P}}</ref><ref name="Cox210">{{cite book|title=Storm Watchers|page=[https://archive.org/details/stormwatcherstur00cox_df1/page/210 210]|year=2002|author=Cox, John D.|publisher=John Wiley & Sons, Inc.|isbn=978-0-471-38108-2|url=https://archive.org/details/stormwatcherstur00cox_df1/page/210}}</ref> Following Phillips' work, several groups began working to create [[general circulation model]]s.<ref name="Lynch Ch10">{{cite book|last=Lynch|first=Peter|title=The Emergence of Numerical Weather Prediction|url=https://archive.org/details/emergencenumeric00lync|url-access=limited|year=2006|publisher=[[Cambridge University Press]]|isbn=978-0-521-85729-1|pages=[https://archive.org/details/emergencenumeric00lync/page/n216 206]–208|chapter=The ENIAC Integrations}}</ref> The first general circulation climate model that combined both oceanic and atmospheric processes was developed in the late 1960s at the [[NOAA]] [[Geophysical Fluid Dynamics Laboratory]].<ref>{{cite web|url=http://celebrating200years.noaa.gov/breakthroughs/climate_model/welcome.html|title=The First Climate Model|author=[[National Oceanic and Atmospheric Administration]]|date=2008-05-22|access-date=2011-01-08}}</ref>

As computers have become more powerful, the size of the initial data sets has increased and [[Atmospheric model#Types|newer atmospheric models]] have been developed to take advantage of the added available computing power. These newer models include more physical processes in the simplifications of the [[Navier–Stokes equations|equations of motion]] in numerical simulations of the atmosphere.<ref name="Harper BAMS"/> In 1966, [[West Germany]] and the United States began producing operational forecasts based on [[primitive equations|primitive-equation models]], followed by the United Kingdom in 1972 and Australia in 1977.<ref name="Lynch JCP"/><ref name="Leslie BOM">{{cite journal|last=Leslie|first=L.M.|author2=Dietachmeyer, G.S. |title=Real-time limited area numerical weather prediction in Australia: a historical perspective|journal=Australian Meteorological Magazine|date=December 1992|volume=41|issue=SP|pages=61–77|url=http://www.bom.gov.au/amoj/docs/1992/leslie2.pdf|access-date=2011-01-03}}</ref> The development of limited area (regional) models facilitated advances in forecasting the tracks of [[tropical cyclone]]s as well as [[air quality]] in the 1970s and 1980s.<ref name="Shuman W&F">{{cite journal|last=Shuman|first=Frederick G.|author-link=Frederick Gale Shuman|title=History of Numerical Weather Prediction at the National Meteorological Center|journal=[[Weather and Forecasting]]|date=September 1989|volume=4|issue=3|pages=286–296|doi=10.1175/1520-0434(1989)004<0286:HONWPA>2.0.CO;2|bibcode=1989WtFor...4..286S|doi-access=free}}</ref><ref>{{cite book|title=Air pollution modeling and its application VIII, Volume 8|author=Steyn, D. G.|publisher=Birkhäuser|year=1991|pages=241–242|isbn=978-0-306-43828-8}}</ref> By the early 1980s models began to include the interactions of soil and vegetation with the atmosphere, which led to more realistic forecasts.<ref>{{cite journal|url=http://www.geog.ucla.edu/~yxue/pdf/1996jgr.pdf |title=Impact of vegetation properties on U. S. summer weather prediction |page=7419 |author1=Xue, Yongkang |author2=Fennessey, Michael J. |journal=[[Journal of Geophysical Research]] |volume=101 |issue=D3 |date=1996-03-20 |access-date=2011-01-06 |doi=10.1029/95JD02169 |bibcode=1996JGR...101.7419X |url-status=dead |archive-url=https://web.archive.org/web/20100710080304/http://www.geog.ucla.edu/~yxue/pdf/1996jgr.pdf |archive-date=2010-07-10 |citeseerx=10.1.1.453.551 }}</ref>

The output of forecast models based on [[atmospheric dynamics]] is unable to resolve some details of the weather near the Earth's surface. As such, a statistical relationship between the output of a numerical weather model and the ensuing conditions at the ground was developed in the 1970s and 1980s, known as [[model output statistics]] (MOS).<ref name="MOS"/><ref>{{cite book|title=Air Weather Service Model Output Statistics Systems|author1=Best, D. L. |author2=Pryor, S. P. |year=1983|pages=1–90|publisher=Air Force Global Weather Central}}</ref> Starting in the 1990s, model ensemble forecasts have been used to help define the forecast uncertainty and to extend the window in which numerical weather forecasting is viable farther into the future than otherwise possible.<ref name="Toth"/><ref name="ECens"/><ref name="RMS"/>