A heavy rain process of the Changjiang-Huaihe Meiyu front (MYF) is diagnosed by the agency of the traditional Q vector partitioning (QVP) method to decompose the wet Q vector (Q) in a natural coordinate system that fo...A heavy rain process of the Changjiang-Huaihe Meiyu front (MYF) is diagnosed by the agency of the traditional Q vector partitioning (QVP) method to decompose the wet Q vector (Q) in a natural coordinate system that follows the isoentropes and by using the numerical simulation results of the revised MM4 meso-scale model. The technique shows that the partitioned wet Q vectors can lead to a significant scale separation of vertical motion related to the torrential rain. The results not only verify the existing conclusion that different scales interact throughout the rainstorm but also indicate the largely different roles of these scales during differing phases of the heavy ramfall on a quantitative basis. Specifically, during the developing stage, the large-scale plays a predominant role in forcing vertical motion, while frontal-scale forcing is secondary; during the intense stage, the frontal-scale evolves into the primary factor of forcing vertical motion, whereas the large-scale forcing is minor and plays a diminishing role and can even be ignored; and during the decaying stage, the large-scale once again serves as the main forcing of vertical motion in such a way that the forcing of the frontal-scale decays quickly and is of secondary importance. Furthermore, the partitioned wet Q vectors are suggested to be more suitable than the total wet Q vector for evaluating the potential physical mechanism of rainstorm genesis. The first step is that the forcing of large-scale $2?bla cdot {? Q}_s^*$ gives rise to the genesis of meso-scale $2?bla cdot {? Q}_n^*$ forcing; and then, accordingly as $2?bla cdot {? Q}_n^*$ forcing increases, whereby the secondary circulation is reinforced, the intensity of the rainfall is strengthened; and at last, the secondary circulation caused by $2?bla cdot {? Q}_n^*$ forcing is directly responsible for generation of the MYF heavy rainfall.展开更多
Based on NCEP/NCAR 1°×1°reanalysis data,according to the non-geostrophic wet Q vector,a rainstorm weather process in Ulanqab from July 24 to 25,2016 was diagnosed and analyzed.The results show that the ...Based on NCEP/NCAR 1°×1°reanalysis data,according to the non-geostrophic wet Q vector,a rainstorm weather process in Ulanqab from July 24 to 25,2016 was diagnosed and analyzed.The results show that the rainstorm area in Ulanqab City had a good corresponding relationship with the convergence area of non-geostrophic wet Q vector and the rising motion area.The rainstorm occurred in the convergence area of non-geostrophic wet Q vector divergence,and the secondary circulation excited by the non-geostrophic wet Q vector was conducive to the maintenance and development of rainstorm.The falling area of rainstorm was located on the side of the ascending branch of the secondary circulation.The non-geostrophic wet Q vector provides a new idea for the forecast of rainstorm and its falling area in Ulanqab.展开更多
利用NCEP1°×1°再分析资料和中国自动气象站与CMORPH融合的逐时降水资料,采用非地转湿Q矢量和水汽通量散度,对2013年7月28—29日一次高原东部切变线引起的强降水进行了诊断分析。研究结果表明强的辐合切变线沿着变形场的...利用NCEP1°×1°再分析资料和中国自动气象站与CMORPH融合的逐时降水资料,采用非地转湿Q矢量和水汽通量散度,对2013年7月28—29日一次高原东部切变线引起的强降水进行了诊断分析。研究结果表明强的辐合切变线沿着变形场的拉伸轴分布,切变线位于上升区和下沉区之间。500 h Pa非地转湿Q矢量与未来6 h的累积降水中心有很好的对应关系。水汽通量散度场显示水汽辐合带基本位于切变线上,风场的分布对水汽的辐合作用尤为重要。水汽辐合带和非地转湿Q矢量辐合带的重叠区对强降水落区有较好的指示意义。展开更多
基金This work was supported by the National Natural Science Foundation of China under Grant Nos.40075009 and 40205008,and by Project 37020 of the Social Public Special Research Grant of the Ministry of Science and Technology of China.
文摘A heavy rain process of the Changjiang-Huaihe Meiyu front (MYF) is diagnosed by the agency of the traditional Q vector partitioning (QVP) method to decompose the wet Q vector (Q) in a natural coordinate system that follows the isoentropes and by using the numerical simulation results of the revised MM4 meso-scale model. The technique shows that the partitioned wet Q vectors can lead to a significant scale separation of vertical motion related to the torrential rain. The results not only verify the existing conclusion that different scales interact throughout the rainstorm but also indicate the largely different roles of these scales during differing phases of the heavy ramfall on a quantitative basis. Specifically, during the developing stage, the large-scale plays a predominant role in forcing vertical motion, while frontal-scale forcing is secondary; during the intense stage, the frontal-scale evolves into the primary factor of forcing vertical motion, whereas the large-scale forcing is minor and plays a diminishing role and can even be ignored; and during the decaying stage, the large-scale once again serves as the main forcing of vertical motion in such a way that the forcing of the frontal-scale decays quickly and is of secondary importance. Furthermore, the partitioned wet Q vectors are suggested to be more suitable than the total wet Q vector for evaluating the potential physical mechanism of rainstorm genesis. The first step is that the forcing of large-scale $2?bla cdot {? Q}_s^*$ gives rise to the genesis of meso-scale $2?bla cdot {? Q}_n^*$ forcing; and then, accordingly as $2?bla cdot {? Q}_n^*$ forcing increases, whereby the secondary circulation is reinforced, the intensity of the rainfall is strengthened; and at last, the secondary circulation caused by $2?bla cdot {? Q}_n^*$ forcing is directly responsible for generation of the MYF heavy rainfall.
文摘Based on NCEP/NCAR 1°×1°reanalysis data,according to the non-geostrophic wet Q vector,a rainstorm weather process in Ulanqab from July 24 to 25,2016 was diagnosed and analyzed.The results show that the rainstorm area in Ulanqab City had a good corresponding relationship with the convergence area of non-geostrophic wet Q vector and the rising motion area.The rainstorm occurred in the convergence area of non-geostrophic wet Q vector divergence,and the secondary circulation excited by the non-geostrophic wet Q vector was conducive to the maintenance and development of rainstorm.The falling area of rainstorm was located on the side of the ascending branch of the secondary circulation.The non-geostrophic wet Q vector provides a new idea for the forecast of rainstorm and its falling area in Ulanqab.
文摘利用NCEP1°×1°再分析资料和中国自动气象站与CMORPH融合的逐时降水资料,采用非地转湿Q矢量和水汽通量散度,对2013年7月28—29日一次高原东部切变线引起的强降水进行了诊断分析。研究结果表明强的辐合切变线沿着变形场的拉伸轴分布,切变线位于上升区和下沉区之间。500 h Pa非地转湿Q矢量与未来6 h的累积降水中心有很好的对应关系。水汽通量散度场显示水汽辐合带基本位于切变线上,风场的分布对水汽的辐合作用尤为重要。水汽辐合带和非地转湿Q矢量辐合带的重叠区对强降水落区有较好的指示意义。
