Using the operational model(B model)of Beijing Meteorological Center,we do some of numerical experi- ments of crossing and rounding mountains in all velocity adjustment scheme,and study dynamic effect of Qinghai-Xizan...Using the operational model(B model)of Beijing Meteorological Center,we do some of numerical experi- ments of crossing and rounding mountains in all velocity adjustment scheme,and study dynamic effect of Qinghai-Xizang Plateau and Rocky Mountains on lee cyclones.The results show that due to air flow round the Qinghai-Xizang Plateau,divergence is distributed in the shape of confluence which matches cyclogenesis area and cyclonic track in East Asia.In the downstream of the Qinghai-Xizang Plateau,convergence in the upper troposphere restrains cyclone development in the east of China mainland.In North America, air flow primarily crosses over Rocky Mountains.Air is adiabatically cooled when it flows upward in the west flank of Rocky Mountains,while air is warmed when it flows downward in the lee side.The fact is important for the lee cyclogenesis and the lee frontogenesis of Rocky Mountains.Air flow crossing over Rocky Mountains is also the main cause for forming dryline in the mid-west of United States.展开更多
Based on the repeated gravity observation data from 1996 to 2007 from the Longmenshan gravity network, which has been dealt with by adjustment processing, the benchmark interference removal and impact of elevation cha...Based on the repeated gravity observation data from 1996 to 2007 from the Longmenshan gravity network, which has been dealt with by adjustment processing, the benchmark interference removal and impact of elevation changes removal, and by using the 3-D inversion method to reflect underground density, we analyze the characteristics of Longmenshan regional dynamic crustal density at depths of 25km, 20km and 15kin. The results show that in the Wenchuan earthquake preparation process, the regional density field showed marked characteristics both in time and space distribution. From the point of time process, the density change trend in the ten years before the earthquake presents a periodic change pattern： steady phase, dramatic stage, slow reducing phase and slow increase phase. The degree of density changes is from large to small, which means that earthquake gestation has reached the final stage. From the point of space distribution, density change distribution has a tendency of ＂dispersion--relative concentration＂, this shows that before the earthquake, the entropy of the underground density field was decreased. In addition, dramatic density changes often occur in the Longmenshan fault zone and western Sichuan plateau. Also, with the increase of depth, the trend of density change is more and more obvious. Through comparative analysis, the influence of density change on gravity is much bigger than that from height change.展开更多
文摘Using the operational model(B model)of Beijing Meteorological Center,we do some of numerical experi- ments of crossing and rounding mountains in all velocity adjustment scheme,and study dynamic effect of Qinghai-Xizang Plateau and Rocky Mountains on lee cyclones.The results show that due to air flow round the Qinghai-Xizang Plateau,divergence is distributed in the shape of confluence which matches cyclogenesis area and cyclonic track in East Asia.In the downstream of the Qinghai-Xizang Plateau,convergence in the upper troposphere restrains cyclone development in the east of China mainland.In North America, air flow primarily crosses over Rocky Mountains.Air is adiabatically cooled when it flows upward in the west flank of Rocky Mountains,while air is warmed when it flows downward in the lee side.The fact is important for the lee cyclogenesis and the lee frontogenesis of Rocky Mountains.Air flow crossing over Rocky Mountains is also the main cause for forming dryline in the mid-west of United States.
基金funded by the National Natural Science Foundation of China(41330314)Projects of Science for Earthquake Resilience(XH15049Y)+1 种基金National Science and Technology Support Program of China(2012BAK19B02,2012BAK19B03)Special Research Foundation for Seismology(201108009)
文摘Based on the repeated gravity observation data from 1996 to 2007 from the Longmenshan gravity network, which has been dealt with by adjustment processing, the benchmark interference removal and impact of elevation changes removal, and by using the 3-D inversion method to reflect underground density, we analyze the characteristics of Longmenshan regional dynamic crustal density at depths of 25km, 20km and 15kin. The results show that in the Wenchuan earthquake preparation process, the regional density field showed marked characteristics both in time and space distribution. From the point of time process, the density change trend in the ten years before the earthquake presents a periodic change pattern： steady phase, dramatic stage, slow reducing phase and slow increase phase. The degree of density changes is from large to small, which means that earthquake gestation has reached the final stage. From the point of space distribution, density change distribution has a tendency of ＂dispersion--relative concentration＂, this shows that before the earthquake, the entropy of the underground density field was decreased. In addition, dramatic density changes often occur in the Longmenshan fault zone and western Sichuan plateau. Also, with the increase of depth, the trend of density change is more and more obvious. Through comparative analysis, the influence of density change on gravity is much bigger than that from height change.
