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
The COVID-19 pandemic,caused by SARS-CoV-2,highlighted heterogeneities in human behavior and attitudes of individuals with respect to adherence or lack thereof to public health-mandated intervention and mitigation mea...The COVID-19 pandemic,caused by SARS-CoV-2,highlighted heterogeneities in human behavior and attitudes of individuals with respect to adherence or lack thereof to public health-mandated intervention and mitigation measures.This study is based on using mathematical modeling approaches,backed by data analytics and computation,to theoretically assess the impact of human behavioral changes on the trajectory,burden,and control of the COVID-19 pandemic during the first two waves in New York City.A novel behavior-epidemiology model,which considers n heterogeneous behavioral groups based on level of risk tolerance and distinguishes behavioral changes by social and disease-related motivations(such as peer-influence and fear of disease-related hospitalizations),is developed.In addition to rigorously analyzing the basic qualitative features of this model,a special case is considered where the total population is stratified into two groups:risk-averse(Group 1)and risk-tolerant(Group 2).The 2-group model was calibrated and validated using daily hospitalization data for New York City during the first wave,and the calibrated model was used to predict the data for the second wave.The 2-group model predicts the daily hospitalizations during the second wave almost perfectly,compared to the version without behavioral considerations,which fails to accurately predict the second wave.This suggests that epidemic models of the COVID-19 pandemic that do not explicitly account for heterogeneities in human behavior may fail to accurately predict the trajectory and burden of the pandemic in a population.Numerical simulations of the calibrated 2-group behavior model showed that while the dynamics of the COVID-19 pandemic during the first wave was largely influenced by the behavior of the risk-tolerant(Group 2)individuals,the dynamics during the second wave was influenced by the behavior of individuals in both groups.It was also shown that disease-motivated behavioral changes(i.e.,behavior changes due to the level of COVID-19 hospitalizations in the community)had greater influence in significantly reducing COVID-19 morbidity and mortality than behavior changes due to the level of peer or social influence or pressure.Finally,it is shown that the initial proportion of members in the community that are risk-averse(i.e.,the proportion of individuals in Group 1 at the beginning of the pandemic)and the early and effective implementation of non-pharmaceutical interventions have major impacts in reducing the size and burden of the pandemic(particularly the total COVID-19 mortality in New York City during the second wave).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.
基金ABG acknowledges the support,in part,of the National Science Foundation(Grant Number:DMS-2052363,transferred to DMS-2330801)AO acknowledges the support of the University of Maryland School of Graduate Studies Dean's Fellowship.
文摘The COVID-19 pandemic,caused by SARS-CoV-2,highlighted heterogeneities in human behavior and attitudes of individuals with respect to adherence or lack thereof to public health-mandated intervention and mitigation measures.This study is based on using mathematical modeling approaches,backed by data analytics and computation,to theoretically assess the impact of human behavioral changes on the trajectory,burden,and control of the COVID-19 pandemic during the first two waves in New York City.A novel behavior-epidemiology model,which considers n heterogeneous behavioral groups based on level of risk tolerance and distinguishes behavioral changes by social and disease-related motivations(such as peer-influence and fear of disease-related hospitalizations),is developed.In addition to rigorously analyzing the basic qualitative features of this model,a special case is considered where the total population is stratified into two groups:risk-averse(Group 1)and risk-tolerant(Group 2).The 2-group model was calibrated and validated using daily hospitalization data for New York City during the first wave,and the calibrated model was used to predict the data for the second wave.The 2-group model predicts the daily hospitalizations during the second wave almost perfectly,compared to the version without behavioral considerations,which fails to accurately predict the second wave.This suggests that epidemic models of the COVID-19 pandemic that do not explicitly account for heterogeneities in human behavior may fail to accurately predict the trajectory and burden of the pandemic in a population.Numerical simulations of the calibrated 2-group behavior model showed that while the dynamics of the COVID-19 pandemic during the first wave was largely influenced by the behavior of the risk-tolerant(Group 2)individuals,the dynamics during the second wave was influenced by the behavior of individuals in both groups.It was also shown that disease-motivated behavioral changes(i.e.,behavior changes due to the level of COVID-19 hospitalizations in the community)had greater influence in significantly reducing COVID-19 morbidity and mortality than behavior changes due to the level of peer or social influence or pressure.Finally,it is shown that the initial proportion of members in the community that are risk-averse(i.e.,the proportion of individuals in Group 1 at the beginning of the pandemic)and the early and effective implementation of non-pharmaceutical interventions have major impacts in reducing the size and burden of the pandemic(particularly the total COVID-19 mortality in New York City during the second wave).
