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Software modularity architecture facilitates software development and software reusability. Software reusability enhances the maintenance of software, facilitates building larger component out of sub-components. Numerical weather ...
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Software modularity architecture facilitates software development and software reusability. Software reusability enhances the maintenance of software, facilitates building larger component out of sub-components. Numerical weather prediction uses complex mathematical models and run them on powerful computers to forecast weather conditions. Numerical weather prediction models have proliferated and can be classified into regional and global models. The Weather Research Forecast model is considered the next-generation mesoscale regional model and widely used. The Weather Research Forecasting model consists of several modules interacting with each other. This research aims to study the WRF?s software architecture, software modules, and the forecasting accuracy of WRF in respect to other well-known Numerical Prediction Models. The study outcomes show that WRF?s software architecture characterized with high degree of flexibility, loosely coupled modules which plays a very important role to obtain accurate forecasting results through the application of independent modules, and consequently it provides a high reliable and accurate forecasting results.
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Mesoscale meteorological modeling was conducted to evaluate air temperature at 2-m above surface (T2), wind speed/direction, and relative humidity (RH) in Singapore, a tropical city, for a dry period. A sensitivity study was condu...
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Mesoscale meteorological modeling was conducted to evaluate air temperature at 2-m above surface (T2), wind speed/direction, and relative humidity (RH) in Singapore, a tropical city, for a dry period. A sensitivity study was conducted to determine the best combination of schemes for the physical modules. The model was used to study the urban heat island (UHI) effect and urban cooling effect by applying cool coating on various urban surfaces. Maximum UHI intensity of 3.2°C is found at nighttime (21:00) at a hot spot in the Commercial/Industrial area. At nighttime, when the UHI effect is generally more intense than daytime, applying cool coating on all urban surfaces can reduce the UHI effect by about 30% in residential areas and about 6% in commercial/industrial areas. Maximum T2 reduction of 3.1°C and surface skin temperature (TSK) reduction of 9.8°C due to cool coating is found at 13:00 at certain locations. The cool urban surfaces reduce radiative heat absorption during daytime, reducing heat storage in urban structures. This leads to subsequent reduction of stored heat release from urban structures, mitigating UHI effect during nighttime. Applying cool coating on horizontal surfaces (roofs and roads) provides more cooling effect than vertical surfaces (walls). Cool roofs provide more cooling effect than cool roads since roofs cover more urban horizontal surfaces than roads do in the current setting. Part of the radiation reflected by cool roads could be absorbed by other urban structures, reducing its cooling effect as compared to cool roofs.
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The Weather Research and Forecasting model with chemistry (WRF-Chem) is used to investigate an intense dust storm event during 26 to 30 July 2006 that originated over the Taklimakan Desert (TD) and transported to the northern slop...
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The Weather Research and Forecasting model with chemistry (WRF-Chem) is used to investigate an intense dust storm event during 26 to 30 July 2006 that originated over the Taklimakan Desert (TD) and transported to the northern slope of Tibetan Plateau (TP). The dust storm is initiated by the approach of a strong cold frontal system over the TD. In summer, the meridional transport of TD dust to the TP is favored by the thermal effect of the TP and the weakening of the East Asian westerly winds. During this dust storm, the transport of TD dust over the TP is further enhanced by the passage of the cold front. As a result, TD dust breaks through the planetary boundary layer and extends to the upper troposphere over the northern TP. TD dust flux arrived at the TP with a value of 6.6 Gg/day in this 5 day event but decays quickly during the southward migration over the TP due to dry deposition. The simulations show that TD dust cools the atmosphere near the surface and heats the atmosphere above with a maximum heating rate of 0.11Kday~(-1) at ~7 km over the TP. The event-averaged net radiative forcings of TD dust over the TP are -3.97, 1.61, and -5.58Wm~(-2) at the top of the atmosphere (TOA), in the atmosphere, and at the surface, respectively. The promising performance of WRF-Chem in simulating dust and its radiative forcing provides confidence for use in further investigation of climatic impact of TD dust over the TP.
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Rainfall is probably the most important parameter that is predicted by numerical weather prediction models, though the skill of rainfall prediction is the poorest compared to other parameters, e.g., temperature and humidity. In th...
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Rainfall is probably the most important parameter that is predicted by numerical weather prediction models, though the skill of rainfall prediction is the poorest compared to other parameters, e.g., temperature and humidity. In this study, the impact of rainfall assimilation on mesoscale model forecasts is evaluated during Indian summer monsoon 2011. The Weather Research and Forecasting (WRF) model and its four-dimensional variational data assimilation system are used to assimilate the Tropical Rainfall Measuring Mission 3B42 and Japan Aerospace Exploration Agency Global Satellite Mapping of Precipitation retrieved rainfall. A total of five experiments are performed daily with and without assimilation of rainfall data during the entire month of July 2011. Separate assimilation experiments are performed to assess the sensitivity of WRF model forecast with strict and less strict quality control. Assimilation of rainfall improves the forecast of temperature, specific humidity, and wind speed. Domain average improvement parameter of rainfall forecast is also improved over the Indian landmass when compared with NOAA Climate Prediction Center Morphing technique and Indian Meteorological Department gridded rainfall.
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On 10 November 1998, a cyclone deepened rapidly as it passed through the upper Midwest, bringing with it damaging winds and record-setting low pressures. An examination of meteorological satellite imagery over the upper Midwest du...
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On 10 November 1998, a cyclone deepened rapidly as it passed through the upper Midwest, bringing with it damaging winds and record-setting low pressures. An examination of meteorological satellite imagery over the upper Midwest during the height of the storm showed an area of drier air curving cyclonically behind the cold front. This dry intrusion forked into two distinct paths near the low-pressure center, with the lowest tropopause heights (approx 600 mb) near the southern fork of the dry intrusion. The main finding of this work is that the surface reports of damaging winds were very closely linked in time and space to the location of the southern fork of the dry intrusion. The possibility of improved nowcasting of extreme winds on very fine space and time scales using satellite imagery is discussed. The satellite signatures of this storm are discussed in relation to other damaging windstorm events, such as the 1979 Fastnet yacht race cyclone and the 1975 Edmund Fitzgerald cyclone.
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The Weather Research and Forecasting (WRF) model includes various configuration options related to physics parameters, which can affect the performance of the model. In this study, numerical experiments were conducted to determine...
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The Weather Research and Forecasting (WRF) model includes various configuration options related to physics parameters, which can affect the performance of the model. In this study, numerical experiments were conducted to determine the best combination of physics parameterization schemes for the simulation of sea surface temperatures, latent heat flux, sensible heat flux, precipitation rate, and wind speed that characterized typhoons. Through these experiments, several physics parameterization options within the Weather Research and Forecasting (WRF) model were exhaustively tested for typhoon Noul, which originated in the South China Sea in November 2008. The model domain consisted of one coarse domain and one nested domain. The resolution of the coarse domain was 30 km, and that of the nested domain was 10 km. In this study, model simulation results were compared with the Climate Forecast System Reanalysis (CFSR) data set. Comparisons between predicted and control data were made through the use of standard statistical measurements. The results facilitated the determination of the best combination of options suitable for predicting each physics parameter. Then, the suggested best combinations were examined for seven other typhoons and the solutions were confirmed. Finally, the best combination was compared with other introduced combinations for windspeed prediction for typhoon Washi in 2011. The contribution of this study is to have attention to the heat fluxes besides the other parameters. The outcomes showed that the suggested combinations are comparable with the ones in the literature.
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The recent expansion of NOAA Weather Radio (NWR) transmitter locations across the U.S. has resulted in increased NWR signal coverage to previously unserved areas. A recent study completed by the Division of Florida Emergency Manag...
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The recent expansion of NOAA Weather Radio (NWR) transmitter locations across the U.S. has resulted in increased NWR signal coverage to previously unserved areas. A recent study completed by the Division of Florida Emergency Management is discussed with suggestions to improve NWR reception in homes and buildings. The signal reception tests were completed for a manufactured home and a home built with metal wall studs with reception results presented. This paper shows that a recently developed external antenna developed from the test results will effectively improve NWR reception in metal buildings and manufactured homes. The importance of effectively educating the public involving correct NWR placement and the use of an external antenna are discussed. It is hoped that the results from this study will aid in the proper public education regarding NWR placement in homes and metal buildings.
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A dynamic irrigation scheme in which soil moisture acts as an irrigation trigger was incorporated into the Weather Research and Forecasting model coupled with the Noah-Mosaic land surface model, in which irrigation was only consid...
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A dynamic irrigation scheme in which soil moisture acts as an irrigation trigger was incorporated into the Weather Research and Forecasting model coupled with the Noah-Mosaic land surface model, in which irrigation was only considered in irrigated portions within each grid cell. Two experiments (with and without irrigation) were first designed and continuously run 21 years (1994-2014) to simulate the impacts of irrigation over Central Asia on regional climate. Soil moisture after irrigation increased greatly because of the large irrigation amount. Irrigation significantly increased latent heat flux through increasing soil evaporation and transpiration, and their contributions to increases in latent heat flux were roughly equal. The sensible heat flux was decreased because of the increased latent heat flux, which led to decreases in surface air temperature and land surface temperature. The simulations of temperature and soil moisture in croplands were improved in experiment with irrigation. The daily minimum surface air temperature was slightly affected by irrigation, even increased during nonirrigation period. During daytime, the airflows blowing from croplands to mountains would also bring parts of the increased water vapor to mountainous areas. Since the increased water vapor was transported upward in mountainous areas, irrigation obviously increased precipitation here. Multiple sensitivity experiments were conducted, and all concluded that irrigation over Central Asia led to increases in precipitation in mountainous areas, which showed that the conclusion was certain and not affected by the selected parameterization schemes and the simulated irrigation amount.
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The "accepted" cause of clear air turbulence that plagues aircraft when flying at high altitudes is Kelvin-Helmholtz instability caused by wind shear. However, environmental Richardson numbers associated with aircraft turbulence r...
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The "accepted" cause of clear air turbulence that plagues aircraft when flying at high altitudes is Kelvin-Helmholtz instability caused by wind shear. However, environmental Richardson numbers associated with aircraft turbulence reports are too highto assume that the turbulence is caused just by the environmental wind shear. Forecast techniques developed to date have assumed that there are layers of local Richardson number favorable for turbulence within the larger layer for which it was measured.The forecasts are probabilistic in the sense that the lower the environmental Richardson number, the more likely somewhere in the layer there will be turbulence. Theory and observations demonstrate that gravity waves can locally modify the wind shear and stability so as to produce turbulence. Analysis of model output associated with clear air turbulence events suggests that turbulence and indicators of large-scale atmospheric imbalance are related. Since highly unbalanced flow must undergo geostrophicadjustment which is a known cause of gravity waves, clear air turbulence may be caused by gravity waves. The conclusion, while preliminary, is that better clear air turbulence forecasts will likely come from an ingredients-based technique that includes both environmental wind shear and gravity wave forcing.
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During the 1998-99 July-June snowfall season, the Mount Baker Ski Area in northwest Washington state reported 1,140 inches of snowfall. As the season progressed and heavy snow continued to fall, the ski area became increasingly aw...
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During the 1998-99 July-June snowfall season, the Mount Baker Ski Area in northwest Washington state reported 1,140 inches of snowfall. As the season progressed and heavy snow continued to fall, the ski area became increasingly aware of the potential to exceed the existing crud accepted record of 1,122 inches, set in 1971-72 at the National Weather Service (NWS) cooperative observing station at Paradise Ranger Station on the southern slopes of Mount Rainier 150 miles to the south. The 1971-72 snowfall was first published as a new U.S. record by the editor of Weatherwise Magazine (Ludlum 1972). Later that year, the value was also recognized by the NWS (Ruscha 1972). The Rainier - Paradise record has been cited as a North American record snowfall byKrause (1998) and others. Because the Mount Baker snowfall is a significant record and would likely be referred to for many years unless exceeded, and because a measure of economic self interest accompanies these measurements, the National Climate Extremes Committee (NCEC) was asked to judge whether the measurement program had adequately followed snowfall observing conventions for acceptance as an official record. The NCEC was formed in 1997 to evaluate the validity of climate extremes that challenge existing national records and make a recommendation to the National Oceanic and Atmospheric Administration (NOAA) regarding acceptance of the observations in question. The NCEC is comprised of several permanent members: National Climatic Data Center, National Weather Service (Andrew Horvitz, Robert Leffler), and the President of the American Association of State Climatologists. Additional experts can also serve as appropriate to the particular record in question. For this event, the chairman was Robert J. Leffler. The Committee also included Kelly Redmond (Western Regional Climate Center) and Raymond Downs (NWS Office of Climate, Water, and Weather Services). The comprehensive evaluation leading to the recommendation that a new record was set is discussed herein. The problems in measuring snow depth are also reiterated.
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