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The Saffir–Simpson hurricane wind scale (SSHWS), formerly the Saffir–Simpson hurricane scale (SSHS), classifies hurricanesWestern Hemisphere tropical cyclones that exceed the intensities of tropical depressions, and tropical stormsinto five categories distinguished by the intensities of their sustained winds. To be classified as a hurricane, a tropical cyclone must have maximum sustained winds of at least (Category 1). The highest classification in the scale, Category 5, is reserved for storms with winds exceeding . The classifications can provide some indication of the potential damage and flooding a hurricane will cause upon landfall. Officially, the Saffir–Simpson hurricane wind scale is used ''only'' to describe hurricanes forming in the Atlantic Ocean and northern Pacific Ocean east of the International Date Line. Other areas use different scales to label these storms, which are called "cyclones" or "typhoons", depending on the area. There is some criticism of the SSHS for not taking rain, storm surge, and other important factors into consideration, but SSHS defenders say that part of the goal of SSHS is to be straightforward and simple to understand. ==History== In 1967 Robert Simpson became the director of the National Hurricane Center and started to look at the problem of communicating the forecasts to the public better. During 1968 Robert spoke to Herbert Saffir about work that he had just completed for the United Nations, about damage to structures that was expected by winds of different strengths. The scale was developed in 1971 by civil engineer Herbert Saffir and meteorologist Robert Simpson, who at the time was director of the U.S. National Hurricane Center (NHC). The scale was introduced to the general public in 1973,〔 〕 and saw widespread use after Neil Frank replaced Simpson at the helm of the NHC in 1974.〔 The initial scale was developed by Saffir, a structural engineer, who in 1969 went on commission for the United Nations to study low-cost housing in hurricane-prone areas.〔 〕 While performing the study, Saffir realized there was no simple scale for describing the likely effects of a hurricane. Mirroring the utility of the Richter magnitude scale in describing earthquakes, he devised a 1–5 scale based on wind speed that showed expected damage to structures. Saffir gave the scale to the NHC, and Simpson added the effects of storm surge and flooding. In 2009, the NHC made moves to eliminate pressure and storm surge ranges from the categories, transforming it into a pure wind scale, called the Saffir–Simpson Hurricane Wind Scale (Experimental) ().〔(The Saffir–Simpson Hurricane Wind Scale ''National Hurricane Center''. Accessed 2009-05-15. )〕 The new scale became operational on May 15, 2010.〔(National Hurricane Operations Plan ), NOAA. Accessed July 3, 2010.〕 The scale excludes flood ranges, storm surge estimations, rainfall, and location, which means a Category 2 hurricane which hits a major city will likely do far more cumulative damage than a Category 5 hurricane that hits a rural area.〔 The agency cited various hurricanes as reasons for removing the "scientifically inaccurate" information, including Hurricane Katrina (2005) and Hurricane Ike (2008), which both had stronger than estimated storm surges, and Hurricane Charley (2004), which had weaker than estimated storm surge.〔(【引用サイトリンク】title=Experimental Saffir–Simpson Hurricane Wind Scale )〕 Since removed from the Saffir-Simpson hurrican wind scale, storm surge predicting and modeling is now handled with the use of a computerized numerical model developed by the National Weather Service called "Sea, Lake, and Overland Surge from Hurricanes" (SLOSH). In 2012, the NHC expanded the windspeed range for Category 4 by 1 mph in both directions, to 130–156 mph, with corresponding changes in the other units (113–136 kn, 209–251 km/h), instead of 131–155 mph (114–135 kn, 210–249 km/h). The NHC and the Central Pacific Hurricane Center assign tropical cyclone intensities in 5 knot increments, and then convert to mph and km/h with a similar rounding for other reports. So an intensity of 115 knots is rated Category 4, but the conversion to miles per hour (132.3 mph) would round down to 130 mph, making it appear to be a Category 3 storm. Likewise, an intensity of 135 knots (~155 mph, and thus Category 4) is 250.02 km/h, which according to the definition used before the change would be Category 5. To resolve these issues, the NHC had been obliged to incorrectly report storms with wind speeds of 115 kn as 135 mph, and 135 kn as 245 km/h. The change in definition allows storms of 115 kn to be correctly rounded down to 130 mph, and storms of 135 kn to be correctly reported as 250 km/h, and still qualify as Category 4. Since the NHC had previously rounded incorrectly to keep storms in Category 4 in each unit of measure, the change does not affect the classification of storms from previous years.〔 The new scale became operational on May 15, 2012.〔(Public Information Statement ), NOAA. Accessed March 9, 2012.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Saffir–Simpson hurricane wind scale」の詳細全文を読む スポンサード リンク
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