A Vision for the National Weather Service Road Map for the Future (1999) / Chapter Skim
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2 Science and Technology
2 Science and Technology
Pages 20-45
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From page 20... ...
Together with observations of cloud types and amounts and precipitation types and intensities, they describe present weather. On longer time scales, climate is defined by these same quantities along with precipitation, land surface temperature, albedo, vegetation, soil moisture, ocean surface temperatures, and atmospheric constituents, such as trace chemical species and aerosols.
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Recent improvements in global analyses have also produced higherquality data describing the global climate. Soil moisture is an important factor in the surface fluxes of water and energy between land and air at a range of spatial and temporal scales.
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. An accurate observational base for soil moisture is also essential for realizing the benefits of distributed hydrologic modeling (see Advanced Forecasting Techniques later in this chapter)
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If the demonstration program is successful, next-generation water vapor sensor systems are likely to be installed on a substantial portion of the domestic air carrier fleet. The future ACARS program may include greater numbers of commercial aircraft, global coverage, an ACARS
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NEXRAD is but one of a number of current weather and aviation Doppler radars. Others include wind profilers that are used to measure winds up to the tropopause, the Terminal Doppler Weather Radar for detecting microbursts and low-level wind shears in airport terminal areas, and the airport surveillance radar (ASR-9)
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Geostationary satellites provide images at high horizontal and temporal resolution, of clouds and total water vapor in tropical and middle latitudes but not over polar regions. Although some progress has been made in deriving vertical soundings of temperature and water vapor from geostationary satellites using infrared and
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Thus, radiometric and radio occultation sounding methods are synergistic, as are geostationary and polarorbiting satellites. A combined system would provide highresolution global coverage, spatially and temporally, of cloud images, temperatures, and water vapory In a report on the continuity of spatial and temporal coverage by the weather satellites in the NESDIS program, the National Weather Service Modernization Committee evaluated NOAA's plans for continuing operations of the geostationary operational environmental satellite (GOES)
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It will also provide the mean boundary layer temperature and column water vapor up to about 1 km, both of which are important for forecasts of clouds, precipitation, and severe storms. Versions of some of these instruments will also be aboard NOAA's operational environmental satellites.
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28 X3dO1 S31 3011S1OS spu!
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offers the possibility of routine, "ridded data that could be assimilated into soil moisture representations for better NWP models. Because continuity in the NESDIS operational satellite program is essential for studies of climate and global change, the National Weather Service Modernization Committee recommended that climate research, such as research being conducted under EOS, be integrated with the NESDIS operational satellite programs (NRC, 1998b)
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obtained through the radio occultation technique will cause the model variables to adjust toward the actual state of the atmosphere. A powerful, though computationally expensive technique for data assimilation is the four-dimensional variational data assimilation, or 4DVAR (Lewis and Derber, 1985; Errico, 1997~.
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These upgrades in computer power were essential for increasing forecast skill. Source: NCEP, personal communication.
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32 100 80 ° 60 o Oh = . _ city 40 20 o / A / \ 1 A VISION FOR THE NATIONAL WEATHER SERVICE: ROAD MAP FOR THE FUTURE A 1950 1960 1970 1980 1990 2000 FIGURE 2-2 The variation since 1949 at NCEP in the skill score of 36-hour forecasts for the sea-level pressure field over North America.
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From page 33... ...
Current Status The current status of several representative operational and research models is summarized in Table 2-2. Operational global models are being run daily out to more than two weeks at approximately 100 km horizontal resolution at NCEP and 60 km at the European Centre for Medium-Range Weather Forecasts (ECMWF)
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27 48 hours NCAR Clark-Hall, clear air turbulence 5 grids (25.6, 6.4, 1.6, 0.4, 0.2 km) 7 hours NCAR Clark-Hall, fire 20 m 160 ~30 minutes a ECMWF = European Centre for Medium-Range Weather Forecasts; NCEP = (U.S.)
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on NWP models. Adapted from Hack Fig.
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To estimate the possible horizontal resolution of global NWP/climate models in 2025, one must make assumptions about the types of models that will be run, the available computer power, and the relationship between model resolution and computer speed. The panel anticipates that there will be three types of global models in 2025: · coupled ocean, atmosphere, land, and sea ice models, also called atmosphere-system models (ASMs)
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Living conditions in a blacked out area could be stressed to the point that evacuations were required. "The magnitude of the disturbances triggered by solar flares is capable of disabling entire utility systems, and the worst is yet to come .
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ADVANCED FORECASTING TECHNIQUES This section highlights four of the emerging techniques in forecasting that are closely linked to recent advances and unresolved issues in meteorology and hydrology: hybrid forecasting, probabilistic forecasting, distributed hydrologic modeling, and quantitative precipitation forecasting (QPF)
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This system uses data from multiple Doppler radars (NEXRAD, Terminal Doppler Weather Radar, and airport surveillance radar) , surface observations from the Advanced Weather Observing System and Low Level Windshear Alert System, a lightning detection network, and measurements from sensors on aircraft.
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A new generation of hydrologic models will be based on characterizing the spatial distribution, over a drainage area, of physical hydrometeorological and hydrologic processes. Distributed hydrologic modeling should replace the spatially lumped soil moisture accounting approach still used by the NWS.
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From page 42... ...
Spatial snow pack conditions in a distributed model, as well as the soil moisture fields, could be initialized and updated using satellite measurements Ultimately, distributed hydrologic models will be fully integrated with regional NWP and nowcasting models for atmospheric processes. Data assimilation (input)
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In addition, much higher resolution NWP models will require a higher density of point observations and higher resolution of remotely observed fields in all three spatial dimensions and in time. Techniques for making quantitative observations of certain variables or characteristics that are now observed poorly, or not at all (e.g., vegetation, soil moisture, or the amounts of water and ice in clouds)
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economic interests through state-of-the-art operations for centralized data assimilation and forecasting. History shows that improvements in NWP forecasts are directly related to increases in computer power.
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The NWS will have to adopt innovative approaches to the development, implementation, and support of distributed hydrologic models; the assimilation of data into these models from the full suite of radar, satellite, and surface observing systems; and the integration of hydrologic models with atmospheric models. In an earlier report, the National Weather Service Modernization Committee recommended that the NWS increase its efforts to meet these objectives (NRC, 1 996a)
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