共查询到2条相似文献,搜索用时 1 毫秒
1.
Thierry Bergot 《Pure and Applied Geophysics》2007,164(6-7):1265-1282
Short-term forecasting of fog is a difficult issue which can have a large societal impact. Fog appears in the surface boundary
layer and is driven by the interactions between land surface and the lower layers of the atmosphere. These interactions are
still not well parameterized in current operational NWP models, and a new methodology based on local observations, an adaptive
assimilation scheme and a local numerical model is tested. The proposed numerical forecast method of foggy conditions has
been run during three years at Paris-CdG international airport. This test over a long-time period allows an in-depth evaluation
of the forecast quality. This study demonstrates that detailed 1-D models, including detailed physical parameterizations and
high vertical resolution, can reasonably represent the major features of the life cycle of fog (onset, development and dissipation)
up to +6 h. The error on the forecast onset and burn-off time is typically 1 h. The major weakness of the methodology is related
to the evolution of low clouds (stratus lowering). Even if the occurrence of fog is well forecasted, the value of the horizontal
visibility is only crudely forecasted. Improvements in the microphysical parameterization and in the translation algorithm
converting NWP prognostic variables into a corresponding horizontal visibility seems necessary to accurately forecast the
value of the visibility. 相似文献
2.
Implementation of a Single-Column Model for Fog and Low Cloud Forecasting at Central-Spanish Airports 总被引:1,自引:0,他引:1
Operations at Central-Spanish airports are often, especially in winter, affected by visibility reduction. The Instituto Nacional de Meteorología (INM), the Spanish Weather Service, has developed a single-column model (SCM) in order to improve short-term forecasts of
fog, visibility and low-clouds. The SCM, called H1D, is a one-dimensional version of the HIRLAM limited-area model. It is
operationally run for three airports in the region: Madrid-Barajas, Almagro and Albacete-Los Llanos. Since SCMs cannot deal
with horizontal heterogeneity, the terms that depend on the horizontal structure of the atmosphere are estimated from the
outputs of the three-dimensional (3-D) model and introduced into the SCM as external forcings. The systematic analysis of
the meteorological situations has evidenced the existence of a close relationship between fog formation and the presence of
drainage winds in the region. Since the 3-D model docs not have the necessary resolution to correctly simulate the main features
of the drainage flow caused by the complex topography in the proximity of Madrid-Barajas, it cannot provide the SCM with the
correct forcings. This problem has been partially overcome through the introduction of a module that, under certain conditions,
substitutes the values computed from the 3-D model outputs by others that are based on a conceptual model of the phenomenon
and have been empirically derived from climatological knowledge. This module improves the H1D verification scores for the
basic meteorological variables—wind, temperature and humidity—and reduces the false alarm rate in fog forecast. 相似文献