- 行业: 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, ...
1. A three-dimensional numerical simulation of turbulent flow in which large eddies (with scales smaller than the overall dimension of the problem in question) are resolved and the effects of subgrid-scale eddies, which are more universal in nature, are parameterized. Large eddies are important in characterizing one turbulent flow from another. The difference between a large eddy simulation and the traditional phenomenological modeling of turbulence is that in the latter case all scales of turbulent motion are parameterized. 2. A modeling technique in which spatial resolution extends into the inertial subrange, but does not resolve the smallest scales of motion. The effects of the latter are approximated using subgrid-scale models, which usually draw heavily on the Kolmogorov theory of the inertial subrange. See direct numerical simulation, very large eddy simulation.
Industry:Weather
A pressure trough formed on the lee side of a mountain range in situations where the wind is blowing with a substantial component across the mountain ridge; often seen on United States weather maps east of the Rocky Mountains, and sometimes east of the Appalachians, where it is less pronounced. Its formation may be explained thermodynamically by the warming due to adiabatic compression of the sinking air on the lee side of the mountain range, or dynamically by generation of cyclonic circulation (cyclogenesis) by the horizontal convergence associated with vertical stretching of air columns passing over the ridge and descending the lee slope. Alternatively, the latter viewpoint is often expressed as the conservation of potential vorticity, where the vertical stretching of the columns is compensated by an increase in their relative vorticity. See lee cyclogenesis.
Industry:Weather
A pressure trough formed on the lee side of a mountain range in situations where the wind is blowing with a substantial component across the mountain ridge; often seen on United States weather maps east of the Rocky Mountains, and sometimes east of the Appalachians, where it is less pronounced. Its formation may be explained thermodynamically by the warming due to adiabatic compression of the sinking air on the lee side of the mountain range, or dynamically by generation of cyclonic circulation (cyclogenesis) by the horizontal convergence associated with vertical stretching of air columns passing over the ridge and descending the lee slope. Alternatively, the latter viewpoint is often expressed as the conservation of potential vorticity, where the vertical stretching of the columns is compensated by an increase in their relative vorticity. See lee cyclogenesis.
Industry:Weather
A four-dimensional data assimilation method that provides an estimate of the model state by evolving explicitly the error covariance of the state estimate. Variants of the Kalman filter algorithm are now being applied to atmospheric data assimilation problems. The filter estimate is based on all data observed up to and including the current time. Generalizations of the Kalman filter exist for continuum dynamics, for nonlinear stochastic systems (e.g., extended or ensemble Kalman filters), for systems that have different types of noise, for unknown noise statistics, and for observations beyond the current time (Kalman smoothers).
Industry:Weather
A four-dimensional data assimilation method that provides an estimate of the model state by evolving explicitly the error covariance of the state estimate. Variants of the Kalman filter algorithm are now being applied to atmospheric data assimilation problems. The filter estimate is based on all data observed up to and including the current time. Generalizations of the Kalman filter exist for continuum dynamics, for nonlinear stochastic systems (e.g., extended or ensemble Kalman filters), for systems that have different types of noise, for unknown noise statistics, and for observations beyond the current time (Kalman smoothers).
Industry:Weather
An unimpeded path between two points in the atmosphere determined by the trajectory of a ray between them. Sometimes synonymous with optical path, a term that may, however, be a shortened form of optical pathlength, which is not the same as line of sight.
Industry:Weather
An unimpeded path between two points in the atmosphere determined by the trajectory of a ray between them. Sometimes synonymous with optical path, a term that may, however, be a shortened form of optical pathlength, which is not the same as line of sight.
Industry:Weather
