By analyzing the heavy fog data in Chizhou City in recent 50 years(1959-2007),the general rules of meteorological elements variations were found when the heavy fog happened.The meteorological elements included the tem...By analyzing the heavy fog data in Chizhou City in recent 50 years(1959-2007),the general rules of meteorological elements variations were found when the heavy fog happened.The meteorological elements included the temperature,humidity,wind direction,wind speed,air pressure and so on.The conceptual models of high-altitude and ground situation were established when the heavy fog happened in Chizhou City.Based on considering sufficiently the special geographical environment in Chizhou City,we found the key factors which affected the local heavy fog via the relative analyses.By using the statistical forecast methods which included the second-level judgment method and regression method of event probability and so on,the forecast mode equation of heavy fog was established.Moreover,the objective forecast system of heavy fog in Chizhou City was also manufactured.It provided the basis and platform which could be referred for the heavy fog forecast,service and the release of early-warning signal.展开更多
Based on the measured data of heavy fog in Wusu County during 1954-2009,its temporal and spatial distribution characteristics were analyzed.The results showed that heavy fog in Wusu mainly happened from later autumn t...Based on the measured data of heavy fog in Wusu County during 1954-2009,its temporal and spatial distribution characteristics were analyzed.The results showed that heavy fog in Wusu mainly happened from later autumn to beginning of the next spring.The most was in December,the least was in January.It had significant regional features and seasonal distribution characteristics.However,the days of heavy fog was irregular,but it was accordant with the decrease trend of frog days in recent years in China,while it was not significant.The situations of high-altitude uniform pressure field and the surface pressure field had a direct relationship with the formation of heavy fog.展开更多
By using the observation data,routine data and NCEP reanalysis data in the automatic station,5 times heavy fog weather processes in Zhangjiajie City in December,2009 were contrasted and analyzed.The results showed tha...By using the observation data,routine data and NCEP reanalysis data in the automatic station,5 times heavy fog weather processes in Zhangjiajie City in December,2009 were contrasted and analyzed.The results showed that 3 conditions were the essential conditions of heavy fog occurrence in Zhangjiajie area.3 conditions were that the wind speed was during 0.1-3.0 m/s,the relative humidity ≥90% and the depression of dew point ΔT ≤1.5 ℃.The fog concentration had no positive correlation relationship with the above conditions.The accumulation of humidity condition in the previous period was also the main reason which affected the generation of heavy fog.The physical quantity field which related to the stability and the relative humidity field which related to the water vapor condition had the certain directive significance for forecasting the heavy fog weather.The fog concentration presented the positive correlation relationship with the inversion intensity.展开更多
The visibility characteristics and meteorological conditions of a sea fog process on 27</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-fa...The visibility characteristics and meteorological conditions of a sea fog process on 27</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> February, 2016 are analyzed and the heavy fog process is simulated by the Weather Research and Forecasting (WRF) model in this paper. The forecast results show that the visibility in Qingdao coastal area is light fog on the night of the 26</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;">. In the WRF simulation, it can be observed from the sea-level pressure that the wind direction of Qingdao and the coastal area turned southerly with the eastward movement of the low pressure system on surface from 1200 UTC to 1800 UTC on the 26</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;">. A large amount of water vapor brought by easterly and southerly wind provides sufficient water vapor conditions for the formation and development of the sea fog. At 975 hPa, there is a strong warm tongue over Shandong Peninsula at 0600 UTC on the 26</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;">, w</span><span><span style="font-family:Verdana;">hile the offshore is affected by the cold tongue, where the horizontal temperature gradient is large and there is a strong baroclinicity. At 850 hPa, there is a weak warm ridge over Qingdao at 1200 UTC on the 26</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;">, which means that it is an inversion layer, which is conducive to the maintenance of fog.展开更多
为了比较不同微物理方案、边界层方案和陆面方案对大雾过程模拟效果的影响,本文利用WRF模式(Weather Research and Forecasting Model)对江苏省高速公路网2011—2013年发生的21场大雾过程进行了数值模拟,探讨了模式不同参数化方案对大...为了比较不同微物理方案、边界层方案和陆面方案对大雾过程模拟效果的影响,本文利用WRF模式(Weather Research and Forecasting Model)对江苏省高速公路网2011—2013年发生的21场大雾过程进行了数值模拟,探讨了模式不同参数化方案对大雾过程数值模拟的影响,确定了基于模式输出结果的成雾判别指标。研究结果表明:(1)综合考虑微物理方案、边界层方案和陆面方案对地面气象要素、高空温度及雾区分布等要素的影响,微物理方案选用WDM6方案,边界层方案选用QNSE方案,陆面方案选用SLAB方案时,雾的数值模拟效果最优;(2)在最优参数化方案设置下,兼顾气象业务部门有限的计算资源和较高的模式垂直分辨率,对21个大雾个例发生的大气背景进行数值模拟和诊断分析后发现:江苏省境内雾的预报指标应为模式最低层(30~40 m高度)液态含水量>0.015 g·kg^(-1),或2 m相对湿度>95%,且10 m风速<3 m·s^(-1)。展开更多
文摘By analyzing the heavy fog data in Chizhou City in recent 50 years(1959-2007),the general rules of meteorological elements variations were found when the heavy fog happened.The meteorological elements included the temperature,humidity,wind direction,wind speed,air pressure and so on.The conceptual models of high-altitude and ground situation were established when the heavy fog happened in Chizhou City.Based on considering sufficiently the special geographical environment in Chizhou City,we found the key factors which affected the local heavy fog via the relative analyses.By using the statistical forecast methods which included the second-level judgment method and regression method of event probability and so on,the forecast mode equation of heavy fog was established.Moreover,the objective forecast system of heavy fog in Chizhou City was also manufactured.It provided the basis and platform which could be referred for the heavy fog forecast,service and the release of early-warning signal.
文摘Based on the measured data of heavy fog in Wusu County during 1954-2009,its temporal and spatial distribution characteristics were analyzed.The results showed that heavy fog in Wusu mainly happened from later autumn to beginning of the next spring.The most was in December,the least was in January.It had significant regional features and seasonal distribution characteristics.However,the days of heavy fog was irregular,but it was accordant with the decrease trend of frog days in recent years in China,while it was not significant.The situations of high-altitude uniform pressure field and the surface pressure field had a direct relationship with the formation of heavy fog.
文摘By using the observation data,routine data and NCEP reanalysis data in the automatic station,5 times heavy fog weather processes in Zhangjiajie City in December,2009 were contrasted and analyzed.The results showed that 3 conditions were the essential conditions of heavy fog occurrence in Zhangjiajie area.3 conditions were that the wind speed was during 0.1-3.0 m/s,the relative humidity ≥90% and the depression of dew point ΔT ≤1.5 ℃.The fog concentration had no positive correlation relationship with the above conditions.The accumulation of humidity condition in the previous period was also the main reason which affected the generation of heavy fog.The physical quantity field which related to the stability and the relative humidity field which related to the water vapor condition had the certain directive significance for forecasting the heavy fog weather.The fog concentration presented the positive correlation relationship with the inversion intensity.
文摘The visibility characteristics and meteorological conditions of a sea fog process on 27</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> February, 2016 are analyzed and the heavy fog process is simulated by the Weather Research and Forecasting (WRF) model in this paper. The forecast results show that the visibility in Qingdao coastal area is light fog on the night of the 26</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;">. In the WRF simulation, it can be observed from the sea-level pressure that the wind direction of Qingdao and the coastal area turned southerly with the eastward movement of the low pressure system on surface from 1200 UTC to 1800 UTC on the 26</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;">. A large amount of water vapor brought by easterly and southerly wind provides sufficient water vapor conditions for the formation and development of the sea fog. At 975 hPa, there is a strong warm tongue over Shandong Peninsula at 0600 UTC on the 26</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;">, w</span><span><span style="font-family:Verdana;">hile the offshore is affected by the cold tongue, where the horizontal temperature gradient is large and there is a strong baroclinicity. At 850 hPa, there is a weak warm ridge over Qingdao at 1200 UTC on the 26</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;">, which means that it is an inversion layer, which is conducive to the maintenance of fog.
文摘为了比较不同微物理方案、边界层方案和陆面方案对大雾过程模拟效果的影响,本文利用WRF模式(Weather Research and Forecasting Model)对江苏省高速公路网2011—2013年发生的21场大雾过程进行了数值模拟,探讨了模式不同参数化方案对大雾过程数值模拟的影响,确定了基于模式输出结果的成雾判别指标。研究结果表明:(1)综合考虑微物理方案、边界层方案和陆面方案对地面气象要素、高空温度及雾区分布等要素的影响,微物理方案选用WDM6方案,边界层方案选用QNSE方案,陆面方案选用SLAB方案时,雾的数值模拟效果最优;(2)在最优参数化方案设置下,兼顾气象业务部门有限的计算资源和较高的模式垂直分辨率,对21个大雾个例发生的大气背景进行数值模拟和诊断分析后发现:江苏省境内雾的预报指标应为模式最低层(30~40 m高度)液态含水量>0.015 g·kg^(-1),或2 m相对湿度>95%,且10 m风速<3 m·s^(-1)。
