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51.
Krocak Makenzie J. Ernst Sean Allan Jinan N. Wehde Wesley Ripberger Joseph T. Silva Carol L. Jenkins-Smith Hank C. 《Natural Hazards》2020,102(3):1351-1368
When the National Weather Service (NWS) issues a tornado warning, the alert is rapidly and widely disseminated to individuals in the general area of the warning. Historically, the assumption has been that a false-negative warning perception (i.e., when someone located within a warning polygon does not believe they have received a tornado warning) carries a higher cost than a false-positive warning perception (i.e., when someone located outside the warning area believes they have received a warning). While many studies investigate tornado warning false alarms (i.e., when the NWS issues a tornado warning, but a tornado does not actually occur), less work focuses on studying individuals outside of the warning polygon bounds who believe they received a warning (i.e., false-positive perceptions). This work attempts to quantify the occurrence of false-positive perceptions and possible factors associated with the rate of occurrence. Following two separate storm events, Oklahomans were asked whether they perceived a tornado warning. Their geolocated responses were then compared to issued warning polygons. Individuals closer to tornado warnings or within a different type of warning (e.g., a severe thunderstorm warning) are more likely to report a false-positive perception than those farther away or outside of other hazard warnings. Further work is needed to understand the rate of false-positive perceptions across different hazards and how this may influence warning response and trust in the National Weather Service.
相似文献52.
Urban areas are faced with mounting demands for managing waste and stormwater for a cleaner environment. Rainfall information is a critical component in efficient management of urban drainage systems. A major water quality impact affecting receiving waterbodies is the discharge of untreated waste and stormwater during precipitation, termed wet weather flow. Elimination or reduction of wet weather flow in metropolitan sewer districts is a major goal of environmental protection agencies and often requires considerable capital improvements. Design of these improvements requires accurate rainfall data in conjunction with monitored wastewater flow data. Characterizing the hydrologic/hydraulic performance of the sewer using distant rain gauges can cause oversizing and wasted expenditures. Advanced technology has improved our ability to measure accurately rainfall over large areas. Weather radar, when combined with rain gauge measurements, provides detailed information concerning rainfall intensities over specific watersheds. Knowing how much rain fell over contributing areas during specific periods aids in characterizing inflow and infiltration to sanitary and combined sewers, calibration of sewer system models, and in operation of predictive real-time control measures. Described herein is the design of a system for managing rainfall information for sewer system management, along with statistical analysis of 60 events from a large metropolitan sewer district. Analysis of the lower quartile rainfall events indicates that the expected average difference is 25.61%. Upper quartile rainfall events have an expected average difference of 17.25%. Rain gauge and radar accumulations are compared and evaluated in relation to specific needs of an urban application. Overall, the events analyzed agree to within ± 8% based on the median average difference between gauge and radar. 相似文献
53.
Six state-of-the-art large-eddy simulation codes were compared in Fedorovich et al. (Preprints, 16th American Meteorological Society Symposium on Boundary Layers and Turbulence, 2004b) for three airflow configurations in order to better understand the effect of wind shear on entrainment dynamics in the convective boundary layer CBL). One such code was the University of Oklahoma large-eddy simulation (LES) code, which at the time employed a second-order leapfrog time-advancement scheme with the Asselin filter. In subsequent years, the code has been updated to use a third-order Runge–Kutta (RK3) time-advancement scheme. This study investigates what effect the upgrade from the leapfrog scheme to RK3 scheme has on turbulence statistics in the CBL differently affected by mean wind shear, also in relation to predictions by other LES codes that participated in the considered comparison exercise. In addition, the effect of changing the Courant number within the RK3 scheme is investigated by invoking the turbulence spectral analysis. Results indicate that low-order flow statistics obtained with the RK3 scheme generally match their counterparts from simulations with the leapfrog scheme rather closely. CBL growth rates due to entrainment in the shear-free case were also similar using both timestepping schemes. It was found, however, that care should be given to the choice of the Courant number value when running LES with the RK3 scheme in the sheared CBL setting. The advantages of the largest possible (based on the stability criterion) Courant number were negated by degrading the energy distribution across the turbulence spectrum. While mean profiles and low-order turbulence statistics were largely unaffected, the entrainment rate was over-predicted compared to that reported in the original code-comparison study. 相似文献
54.
Prototyping an experimental early warning system for rainfall-induced landslides in Indonesia using satellite remote sensing and geospatial datasets 总被引：10，自引：2，他引：8
Zonghu Liao Yang Hong Jun Wang Hiroshi Fukuoka Kyoji Sassa Dwikorita Karnawati Faisal Fathani 《Landslides》2010,7(3):317-324
An early warning system has been developed to predict rainfall-induced shallow landslides over Java Island, Indonesia. The
prototyped early warning system integrates three major components: (1) a susceptibility mapping and hotspot identification
component based on a land surface geospatial database (topographical information, maps of soil properties, and local landslide
inventory, etc.); (2) a satellite-based precipitation monitoring system () and a precipitation forecasting model (i.e., Weather Research Forecast); and (3) a physically based, rainfall-induced landslide
prediction model SLIDE. The system utilizes the modified physical model to calculate a factor of safety that accounts for
the contribution of rainfall infiltration and partial saturation to the shear strength of the soil in topographically complex
terrains. In use, the land-surface “where” information will be integrated with the “when” rainfall triggers by the landslide
prediction model to predict potential slope failures as a function of time and location. In this system, geomorphologic data
are primarily based on 30-m Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data, digital elevation
model (DEM), and 1-km soil maps. Precipitation forcing comes from both satellite-based, real-time National Aeronautics and
Space Administration (NASA) Tropical Rainfall Measuring Mission (TRMM), and Weather Research Forecasting (WRF) model forecasts.
The system’s prediction performance has been evaluated using a local landslide inventory, and results show that the system
successfully predicted landslides in correspondence to the time of occurrence of the real landslide events. Integration of
spatially distributed remote sensing precipitation products and in-situ datasets in this prototype system enables us to further
develop a regional, early warning tool in the future for predicting rainfall-induced landslides in Indonesia. 相似文献