The Weather Research and Forecasting (WRF) model was used to investigate the role of downward momentum transport in the formation of severe surface winds for a squall line on 3-4 June 2009 across regions of the Henan ...The Weather Research and Forecasting (WRF) model was used to investigate the role of downward momentum transport in the formation of severe surface winds for a squall line on 3-4 June 2009 across regions of the Henan and Shandong Provinces of China. The results show that there was a strong westerly jet belt with a wind speed greater than 30 m s 1 and a thickness of 5 km at an altitude of 11-16 km. The jet belt was accelerated, and it descended while the squall line convective system occurred. It was found that the appearance of strong negative perturbation pressure accompanied by the squall line caused the acceleration of the upper-level westerly jet and increased the horizontal wind speed by a maximum of 18%. Meanwhile, the negative buoyancy due to the loading, melting, and evaporation of cloud hydrometeors induced the downward momentum transport from the upper levels. The downward momentum transport contributed approximately 70% and the surface cold pool 30% to the formation of severe surface winds.展开更多
Based on NCEP reanalysis data,EDAS data and ground observation data,the causes of a strong sandstorm process in Ulanqab City from March 14 to 15,2021 were analyzed.The analysis shows that"3.15"sandstorm,a sa...Based on NCEP reanalysis data,EDAS data and ground observation data,the causes of a strong sandstorm process in Ulanqab City from March 14 to 15,2021 were analyzed.The analysis shows that"3.15"sandstorm,a sandstorm process accompanied by northwest gale behind the front,was caused by strong cold air in the north.In the early stage,the Mongolian cyclone resulted in the increase of temperature and decrease of pressure on the ground.When a strong surface cold high pressure at the rear of the cyclone invaded the city,a strong pressure gradient between high and low pressure provided dynamic conditions for the sandstorm outbreak.The transit of the surface cold front was the sign of the sandstorm outbreak,and the downward transmission of momentum at high altitudes increased the wind speed near the surface.展开更多
基金supported by the National Meteorology Public Welfare Industry Research Project(GYHY200806001)the National Science and Technology Support Program (2006BAC12B03)
文摘The Weather Research and Forecasting (WRF) model was used to investigate the role of downward momentum transport in the formation of severe surface winds for a squall line on 3-4 June 2009 across regions of the Henan and Shandong Provinces of China. The results show that there was a strong westerly jet belt with a wind speed greater than 30 m s 1 and a thickness of 5 km at an altitude of 11-16 km. The jet belt was accelerated, and it descended while the squall line convective system occurred. It was found that the appearance of strong negative perturbation pressure accompanied by the squall line caused the acceleration of the upper-level westerly jet and increased the horizontal wind speed by a maximum of 18%. Meanwhile, the negative buoyancy due to the loading, melting, and evaporation of cloud hydrometeors induced the downward momentum transport from the upper levels. The downward momentum transport contributed approximately 70% and the surface cold pool 30% to the formation of severe surface winds.
文摘Based on NCEP reanalysis data,EDAS data and ground observation data,the causes of a strong sandstorm process in Ulanqab City from March 14 to 15,2021 were analyzed.The analysis shows that"3.15"sandstorm,a sandstorm process accompanied by northwest gale behind the front,was caused by strong cold air in the north.In the early stage,the Mongolian cyclone resulted in the increase of temperature and decrease of pressure on the ground.When a strong surface cold high pressure at the rear of the cyclone invaded the city,a strong pressure gradient between high and low pressure provided dynamic conditions for the sandstorm outbreak.The transit of the surface cold front was the sign of the sandstorm outbreak,and the downward transmission of momentum at high altitudes increased the wind speed near the surface.
