| With the development of modern transportation, the expanding of the total transport infrastructure provides convenience to people’s lives. At the same time, the various types of adverse weather for traffic posed a serious threat to the safety of people’s lives and property. Precipitation has a great impact on road safety, so the formation mechanism of precipitation and its impact on road conditions is particularly important.In this paper, the data of GFS (Global Forecasting System) for0.5°×0.5°on the analyzed and forecasted field and WRF (Weather Research and Forecasting model) for Version3.1.1, a mesoscale numerical model were used to the simulations and diagnostic analysis of a torrential rain event occurring in the southern Jiangsu covered the Shanghai-Nanjing Expressway, the Expressway along the Yangtze River and the Nanjing-Changzhou Expressway during17th to18th, June in2011. The verification of the observed data from AWMS (the automatic weather monitoring system) on these expressways and the conventional meteorological stations on the simulations and diagnostic analysis displayed:(1) the simulations and diagnostic analysis on this torrential rain process was ideal and WRF model has a good forecasting ability on a rainfalling process.(2) the coupling of the low-level jet with the upper-level jet was the main dynamical mechanism of this torrential rain process outbreaking and the southwest low-level jet provided a conveying passageway of water vapor for the engendering of heavy rain in this process.(3) There were the negative vertical helicity at the upper levels and the positive vertical helicity at the lower levels.(4) the activity of dry air played an important role for the engendering of heavy rainfall.(5) heavy rainfall is one of the important factors influencing on the visibility of road transportation. The relationship between the horizontal visibility and rainfall strength on the expressways was negative exponential.Using the conventional meteorological elements (temperature, air pressure, wind speed, precipitation, relative humidity) to calculate the amount of road surface water, and discussing the trending of the road surface temperature, precipitation, the road area water:(1) the trend of the every layers temperature at Changzhou station are consistent on summer, the temperature is closed when precipitation occurred.(2) using the trending of the road surface temperature to describe road surface state show that the trending of calculation and the road surface temperature have a good consistency;(3) Using the WRF to simulated this precipitation process, and using the model output value to calculate road state. The result of model value and the actual value are largely consistent.In this paper, in addition to analyze the generation mechanism, structure characteristic and the simulation results of rainstorm, the simulation results of pattern is also analyzed. In this paper, mainly to discuss the impact on the simulation results for the different microphysical parameterization schemes. The coupling of the micro-physical process parameterization schemes are the Ferrier, Kessler-Scheme, Lin et al scheme:(1) due to the mode its own reasons, and the different microphysical parameterization schemes, the precipitation appears of simulation are lag;(2) the three programs results have little difference when the precipitation values are consistency;(3) in addition to the extreme moment, the calculation of the water for road surface have little difference with the measured values (4) Because of the advantages of the mode, it has extent guidance for forecasting the state of road surface.(5) Ferrier is better than other schemes. |
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