- Sektör: Weather
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The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, AMS has a membership of more than 14,000 professionals, ...
A process of modifying a time series of data whereby the beginning and ending 10% of the data points are smoothly reduced in amplitude to approach zero at the ends. Such conditioning of raw data is often necessary before performing a spectral or Fourier analysis. If this were not done, it is possible that spurious spectral signals might be introduced because the Fourier analysis assumes that the finite-duration time series is cyclic (which could cause a step discontinuity between the end of the series and the beginning of the repeated series). However, any time that data are modified, including the conditioning described here, the validity of the resulting analysis may be questioned.
Industry:Weather
A recession curve of streamflow so adjusted that the slope of the curve represents the runoff depletion rate of the groundwater. A curve is formed by the observed hydrograph during prolonged periods of no precipitation.
Industry:Weather
A range of turbulent eddies in a stably stratified atmosphere, too small to be influenced by shear but large enough to be affected by buoyancy. Dimensional considerations give a power law dependence of energy versus wavenumber, or spectral slope, of −11/5. See turbulence spectrum.
Industry:Weather
A radar system configuration with the receiver located at a site different from the transmitter. In such a system, surfaces of constant range are ellipsoids with the transmitter and receiver sites as foci, and the component of target velocity that induces a Doppler frequency shift is the component normal to the ellipsoids.
Industry:Weather
A physical problem completely specified by a differential equation in an unknown, valid in certain information (boundary conditions) about the unknown given on the boundaries of that region. The information required to determine the solution depends completely and uniquely on the particular problem. A great variety of meteorological problems are formulated as boundary-value problems.
Industry:Weather
A period of warm climate beginning abruptly approximately 14 700 years ago, following the end of the Pleistocene, and extending to approximately 12 700 years ago. This warm period ended with a return to cold conditions during the Younger Dryas. Traditionally, this period is divided into the Bolling (warm), Older Dryas (cold), and Allerod (warm) intervals, but recent, more detailed climatic records indicate that the entire Bolling–Allerod period was generally warm with several abrupt coolings.
Industry:Weather
A period of more continental climate 5000 to 7000 years ago identified as part of the Blytt– Sernander sequence of inferred climates in northern Europe.
Industry:Weather
A net pyrradiometer that measures the balance or difference in hemispheric (2π) radiation incident on both sides of a flat surface.
Industry:Weather
A circular evaporation pan, six feet in diameter and two feet deep, made of unpainted galvanized iron. The pan is buried in the ground so that about two inches of the rim extend above the surrounding ground, and the water level is maintained at about ground level. This installation reduces the temperature variations in the pan and causes its pan coefficient to be nearer unity than that of exposed pans. The average pan coefficient is reported to be about 0. 9. The initials BPI stand for Bureau of Plant Industry (U. S. Department of Agriculture), which first introduced this instrument.
Industry:Weather
A nautical term for the strong and rather persistent westerly winds over the oceans in temperate latitudes. They occur between latitudes 40° and 65° in the Northern Hemisphere and 35° to 65° in the Southern Hemisphere, where they are more regular and are strongest between 40° and 50°S (roaring forties). They are associated with the strong pressure gradient on the equatorial side of the frequent depressions passing eastward in subpolar temperate latitudes; hence they fluctuate mainly between southwest and northwest.
Industry:Weather
