Three-dimensional simulation of cold-front rain-band (NCFR) associated with a straight cold front has been studied by use of a non-hydrostatic, full compressible storm-scale model (ARPS) including multi-phase microphy...Three-dimensional simulation of cold-front rain-band (NCFR) associated with a straight cold front has been studied by use of a non-hydrostatic, full compressible storm-scale model (ARPS) including multi-phase microphysical parameterization. The dynamical and physical features of the frontal cloud de-velopment have been well simulated and analyzed. It is in evidence that the frontal cloud is triggered by the updraft of the secondary frontal circulation. However, the long persistence of diabatic frontogenesis only can be attributed to positive feedback between the frontal baroclinicity and the prefrontal latent heat release. The simulations indeed demonstrate that the potential temperature gradient enhancement in front zone is strongly related with the re-distribution of cloud moisture, by the action of tilted updraft. In conse-quence, the splice of cooling and heating pool that is respectively created from the evaporation of cloud wat-er and condensing J freezing of water vapor J rain droplet, wich is in favor of the strong contrast of cool and warm air mass across the frontal zone to diabatic frontogenesis.展开更多
The strong vortex will mutually adjust the thermodynamic field and dynamic field to a state of gradient balance whilst forced by an external cold source,namely,the gradient adjustment process,in which a linearized two...The strong vortex will mutually adjust the thermodynamic field and dynamic field to a state of gradient balance whilst forced by an external cold source,namely,the gradient adjustment process,in which a linearized two-layer model is dealt with in this paper.The analyses show that on account of the heterogeneous radial distribution of the cold source,the adjustment of the thermodynamic and dynamic fields results in the two-peak tangential wind feature,which is analogous to the character of concentric double eyewalls in the strong typhoon.Consequently,the gradient adjustment may be one possible mechanism for the formation of a concentric double-eye typhoon.展开更多
The Variational Optimization Analysis Method （VOAM） for 2-D flow field suggested by Sasaki was reviewed first. It is known that the VOAM can he used efficiently in most cases. However, in the cases where there are h...The Variational Optimization Analysis Method （VOAM） for 2-D flow field suggested by Sasaki was reviewed first. It is known that the VOAM can he used efficiently in most cases. However, in the cases where there are high frequency noises in 2-D flow field, it appears to be inefficient. In the present paper, based on Sasaki＇s VOAM, a Generalized Variational Optimization Analysis Method （GVOAM） was proposed with regularization ideas, which could deal well with flow fields containing high frequency noises. A numerical test shows that observational data can be both variationally optimized and filtered, and therefore the GVOAM is an efficient method.展开更多
In the context of a non-hydrostatic axisymmetric compressible numerical model,the concentric double eyewall structure of the typhoon was replicated well to discuss the formation mechanism of concentric eyewall with th...In the context of a non-hydrostatic axisymmetric compressible numerical model,the concentric double eyewall structure of the typhoon was replicated well to discuss the formation mechanism of concentric eyewall with the aid of gradient wind adjustment.Evidence suggests that in the weakening phase of the typhoon,the heterogeneous radial distribution of the sensible and convective latent heating over the sea surface will induce the gradient wind unbalance accompanied by mutual gradient wind adjustment between the thermodynamic field and dynamic fields,which results in a two-peak tangential wind and concentric double eyewall structure.展开更多
基金We would like to thank Prof. Zhou Xiaoping (LASG, Institute of Atmospheric Physics, Chinese Academy ofSciences) for blithesome co-operating at LASG. Thanks are given to Prof. Wei Shaoyuan (PLA Science and Engi-neering University), Prof Tan Zhemin, and ad
文摘Three-dimensional simulation of cold-front rain-band (NCFR) associated with a straight cold front has been studied by use of a non-hydrostatic, full compressible storm-scale model (ARPS) including multi-phase microphysical parameterization. The dynamical and physical features of the frontal cloud de-velopment have been well simulated and analyzed. It is in evidence that the frontal cloud is triggered by the updraft of the secondary frontal circulation. However, the long persistence of diabatic frontogenesis only can be attributed to positive feedback between the frontal baroclinicity and the prefrontal latent heat release. The simulations indeed demonstrate that the potential temperature gradient enhancement in front zone is strongly related with the re-distribution of cloud moisture, by the action of tilted updraft. In conse-quence, the splice of cooling and heating pool that is respectively created from the evaporation of cloud wat-er and condensing J freezing of water vapor J rain droplet, wich is in favor of the strong contrast of cool and warm air mass across the frontal zone to diabatic frontogenesis.
基金the National Natural Science Foundation of China under Grants 40205009,40175005,40075011 and 40333025the Education Department of Jiangsu Province,and the Nanjing University Postdoctoral Foundation
文摘The strong vortex will mutually adjust the thermodynamic field and dynamic field to a state of gradient balance whilst forced by an external cold source,namely,the gradient adjustment process,in which a linearized two-layer model is dealt with in this paper.The analyses show that on account of the heterogeneous radial distribution of the cold source,the adjustment of the thermodynamic and dynamic fields results in the two-peak tangential wind feature,which is analogous to the character of concentric double eyewalls in the strong typhoon.Consequently,the gradient adjustment may be one possible mechanism for the formation of a concentric double-eye typhoon.
基金Project supported by the National Natural Science Foundation of China (Grant No :90411006) and the Association ofScience and Technology of Shanghai (Grant No :02DJ14032) .
文摘The Variational Optimization Analysis Method （VOAM） for 2-D flow field suggested by Sasaki was reviewed first. It is known that the VOAM can he used efficiently in most cases. However, in the cases where there are high frequency noises in 2-D flow field, it appears to be inefficient. In the present paper, based on Sasaki＇s VOAM, a Generalized Variational Optimization Analysis Method （GVOAM） was proposed with regularization ideas, which could deal well with flow fields containing high frequency noises. A numerical test shows that observational data can be both variationally optimized and filtered, and therefore the GVOAM is an efficient method.
基金the National Natural Science Foundation of Chinas under Grants 40205009,40175005,40075011 and 40333025the Education Department of Jiangsu Province and Nanjing University Postdoctoral Foundation
文摘In the context of a non-hydrostatic axisymmetric compressible numerical model,the concentric double eyewall structure of the typhoon was replicated well to discuss the formation mechanism of concentric eyewall with the aid of gradient wind adjustment.Evidence suggests that in the weakening phase of the typhoon,the heterogeneous radial distribution of the sensible and convective latent heating over the sea surface will induce the gradient wind unbalance accompanied by mutual gradient wind adjustment between the thermodynamic field and dynamic fields,which results in a two-peak tangential wind and concentric double eyewall structure.
