Numerical simulation of a heavy rainfall case in Henan area during 16-17 July 2004 is performed using the LASG （State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics） me...Numerical simulation of a heavy rainfall case in Henan area during 16-17 July 2004 is performed using the LASG （State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics） mesoscale model AREM （Advanced Regional Eta Model） developed by Yu （1989） and Yu et al. （1994）. The results are shown： the air in the middle part of troposphere within the horizontal range of meso-β scale convective system is heated by condensation latent heat. The isobaric surface in the middle and upper part of troposphere is rising, and thus meso-β scale high is formed; the isobaric surface in the lower part of troposphere is depressed, and thus meso-β high and low layer flow promotes the strong development scale low is formed. The interaction between the of the vertical motion. While the rising motion is developing strongly, obvious compensation sinking motion appears around it. In the south of rising motion region, the divergence current in the upper part of troposphere backflows towards south, which leads to the vertical circulation appearing in the upper part of troposphere. The sinking branch of the circulation integrates in the compensation sinking air current in the south of rising motion region and takes the horizontal momentum of upper air to the lower part of troposphere and forms a new meso-β scale jet. In the north of the rising motion region, a mesoscale vertical circulation develops in the low layer of troposphere. The divergence current of the sinking branch of the circulation, which flows southward, converges with warm and humid air current in the low layer of troposphere which flows from southwest, and forms a meso-β scale convergence line. Then it strengthens the convergence over the low level of heavy rain area. In the east of the rising motion region, a mesoscale vertical circulation also develops in low layer of troposphere. The divergence current of the sinking branch of the circulation, which flows westward, causes originally more consistent southwest air current in this region to the east deflection, and thus forms the cyclone curve in the southwest air current. The convergence is further strengthened in the meso-β scale convergence line. The strong development of ageostrophic vorticity in the lower part of troposphere is the important factor of the formation of the meso-β scale cyclone. At last the three-dimensional structure chart of development of heavy rain meso-β scale stream filed is given.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.40575029the Commonweal Special Project "Study of flood-leading rainstorm forecast and warning system in South China" of the Ministry of Science and Technology.
文摘Numerical simulation of a heavy rainfall case in Henan area during 16-17 July 2004 is performed using the LASG （State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics） mesoscale model AREM （Advanced Regional Eta Model） developed by Yu （1989） and Yu et al. （1994）. The results are shown： the air in the middle part of troposphere within the horizontal range of meso-β scale convective system is heated by condensation latent heat. The isobaric surface in the middle and upper part of troposphere is rising, and thus meso-β scale high is formed; the isobaric surface in the lower part of troposphere is depressed, and thus meso-β high and low layer flow promotes the strong development scale low is formed. The interaction between the of the vertical motion. While the rising motion is developing strongly, obvious compensation sinking motion appears around it. In the south of rising motion region, the divergence current in the upper part of troposphere backflows towards south, which leads to the vertical circulation appearing in the upper part of troposphere. The sinking branch of the circulation integrates in the compensation sinking air current in the south of rising motion region and takes the horizontal momentum of upper air to the lower part of troposphere and forms a new meso-β scale jet. In the north of the rising motion region, a mesoscale vertical circulation develops in the low layer of troposphere. The divergence current of the sinking branch of the circulation, which flows southward, converges with warm and humid air current in the low layer of troposphere which flows from southwest, and forms a meso-β scale convergence line. Then it strengthens the convergence over the low level of heavy rain area. In the east of the rising motion region, a mesoscale vertical circulation also develops in low layer of troposphere. The divergence current of the sinking branch of the circulation, which flows westward, causes originally more consistent southwest air current in this region to the east deflection, and thus forms the cyclone curve in the southwest air current. The convergence is further strengthened in the meso-β scale convergence line. The strong development of ageostrophic vorticity in the lower part of troposphere is the important factor of the formation of the meso-β scale cyclone. At last the three-dimensional structure chart of development of heavy rain meso-β scale stream filed is given.
