By adopting the idea of three-dimensional Walker, Hadley and Rossby stream functions, the global atmospheric circulation can be considered as the sum of three stream functions from a global perspective. Therefore, a m...By adopting the idea of three-dimensional Walker, Hadley and Rossby stream functions, the global atmospheric circulation can be considered as the sum of three stream functions from a global perspective. Therefore, a mathematical model of three-dimensional展开更多
The theoretical solution of the model of the Northern Yellow (Huanghai) Sea Cold Water Mass (NYSCWM) reveals that the NYSCWM is mainly formed through the continuous temperature increase of the overwintered water body ...The theoretical solution of the model of the Northern Yellow (Huanghai) Sea Cold Water Mass (NYSCWM) reveals that the NYSCWM is mainly formed through the continuous temperature increase of the overwintered water body above the Northern Yellow Sea Depression (NYSD) after spring when heat is continuously conducted from the sea surface to the’deeper layer. In the NYSCWM’s growing period, (June-July), nonlinear, vertical convection and advection effects continuously increase, and are gradually balanced by the heat diffusion effect as the temperature increases from the surface to the bottom, which leads to the formation of an intensive thermocline and lateral front. Meanwhile, the three-dimensional circulation correspondingly occurs. In the NYSCWM’s entire growing period, the horizontal circulation is always in the cyclonic motion, while the vertical circulation passes through a transition from a period with the cold centre as downwelling to a period with the cold centre as upwelling.展开更多
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the National Basic Research Program of China (Grant Nos. 2006CB403607 and 2006CB400503)the National Natural Science Foundation of China (Grant Nos. 40475027 and 40575028)
文摘By adopting the idea of three-dimensional Walker, Hadley and Rossby stream functions, the global atmospheric circulation can be considered as the sum of three stream functions from a global perspective. Therefore, a mathematical model of three-dimensional
基金Project supported by the National Natural Science Foundation of China.
文摘The theoretical solution of the model of the Northern Yellow (Huanghai) Sea Cold Water Mass (NYSCWM) reveals that the NYSCWM is mainly formed through the continuous temperature increase of the overwintered water body above the Northern Yellow Sea Depression (NYSD) after spring when heat is continuously conducted from the sea surface to the’deeper layer. In the NYSCWM’s growing period, (June-July), nonlinear, vertical convection and advection effects continuously increase, and are gradually balanced by the heat diffusion effect as the temperature increases from the surface to the bottom, which leads to the formation of an intensive thermocline and lateral front. Meanwhile, the three-dimensional circulation correspondingly occurs. In the NYSCWM’s entire growing period, the horizontal circulation is always in the cyclonic motion, while the vertical circulation passes through a transition from a period with the cold centre as downwelling to a period with the cold centre as upwelling.
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.
