Advancing the Understanding and Forecasting of Mesoscale Weather in the United States (1990) / Chapter Skim
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Status of Technology and Science in Mesoscale Meteorology
Status of Technology and Science in Mesoscale Meteorology
Pages 13-24
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From page 13... ...
A key to progress is the ability to process so-called raw observations, such as radar reflectivity, radar Doppler velocity, and satellite-observed infrared radiance, into meteorological information, such as three-dimensional wind velocity, temperature, and moisture. For example, fields of radial velocity from Doppler radars have been combined with data from multiple wind profilers to derive upper-atmospheric wind fields having much higher horizontal resolution than do those obtainable from traditional wind-observing systems.
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From page 14... ...
Computerized atmospheric models are planned that will integrate diverse observational data in a physically and dynamically consistent manner, resulting in improved accuracy and predictive capability, but much additional research and development are needed to achieve this goal. The prospects for rapid technological progress in the observing and processing of mesoscale meteorological data are bright, and new ideas continue to be proposed.
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From page 16... ...
A highaltitude, downward-pointing airborne radar design will measure vertical air motions in unprecedented detail. Advanced ground-based radar techniques use polarization diversity for discrimination of the ice and water phases, detection of hail, and better estimation of very heavy rainfall.
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From page 18... ...
Combined with temperature and moisture data from satellites and balloons, wind profiler observations will lead to improved forecasts of local weather. Critically important for the detection of locally violent weather is the NEXRAD system, which is capable of sensing hazardous wind shears, tornadoes, and downbursts -- major causes of loss of life and property in the United States.
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From page 19... ...
They also can simulate mesoscale features such as precipitation bands, sea breezes, regions of stratiform precipitation, frontal zones, orographic systems, polar lows, mountain-valley circulations, lake-induced vortices, internal gravity waves, and areas of heavy precipitation. The large breadth and extent of mesoscale modeling activity are evident from the great number and diversity of mesoscale models active in 1988 (Appendix Table A.3)
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From page 20... ...
ADVANCES IN FUNDAMENTAL UNDERSTANDING Using sophisticated new observing tools, advanced high-speed computers, and complex computer models, meteorologists have advanced our understanding of storm structure and dynamics and the physical processes leading to precipitation and severe weather. (See Appendix Table A.4, which summarizes the principal U.S.
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From page 21... ...
At the same tune, processes of storm initiation and evolution, such as the growth of convective cloud systems by individual cloud mergers, the behavior of intersecting gust fronts and gravity waves emitted by neighboring clouds, the development of large cold pools by evaporation of precipitation in downdrafts, the systematic release of latent heat in the upper troposphere by anvil clouds, and the role of topographic features such as mountains and land-water thermal contrasts, are all now better understood. Much has been learned about the structure of individual convective storms and the processes governing storm intensity.
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From page 22... ...
In some instances, the vortex grows large enough and persists long enough to become incrtially stable and is instrumental in initiating several new mesoscale convective systems over a period of several days. MCCs typically produce heavy rains and prolific lightning, and occasionally tornadoes and haiL Some 25 percent or more of the MCCs produce severe straight-line winds in swaths that may be 50 to 100 km in width and several hundred kilometers in length.
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From page 23... ...
Intensification of coastal winter storms has been related to energy transfers from the warm ocean surface, latent heat liberated in convective and stratiform clouds, and dynamic instabilities associated with both lower- and upper-tropospheric wind maxima. Scaleinteractive mesoscale processes can cause severe winter storms to develop in a surprisingly short period of time.
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From page 24... ...
Organized mesoscale circulations, such as clusters of individual mesoscale convective clouds within extratropical cyclones, can sweep large volumes of polluted air into regions of moist convection, where the pollutants are transported aloft and scavenged through precipitation. One such system can scavenge enough acidic contaminants to dominate the annual average chemistry of a given watershed or local ecological system.
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