With an increase in model resolution,compact high-order numerical advection scheme can improve its effectiveness and competitiveness in oceanic modeling due to its high accuracy and scalability on massive-processor co...With an increase in model resolution,compact high-order numerical advection scheme can improve its effectiveness and competitiveness in oceanic modeling due to its high accuracy and scalability on massive-processor computers.To provide high-quality numerical ocean simulation on overset grids,we tried a novel formulation of the fourth-order multi-moment constrained finite volume scheme to simulate continuous and discontinuous problems in the Cartesian coordinate.Utilizing some degrees of freedom over each cell and derivatives at the cell center,we obtained a two-dimensional(2D)cubic polynomial from which point values on the extended overlap can achieve fourth-order accuracy.However,this interpolation causes a lack of conservation because the flux between the regions are no longer equal;thus,a flux correction is implemented to ensure conservation.A couple of numerical experiments are presented to evaluate the numerical scheme,which confirms its approximately fourth-order accuracy in conservative transportation on overset grid.The test cases reveal that the scheme is effective to suppress numerical oscillation in discontinuous problems,which may be powerful for salinity advection computing with a sharp gradient.展开更多
为提高中国东部区域夏季降水预估的可靠性,利用第六次耦合模式比较计划(Coupled Model Intercomparison Project Phase6,CMIP6)中的全球气候模式以及4个初值大样本的模拟结果,通过“完美模式”可靠性评估框架,对结合模式模拟性能和独立...为提高中国东部区域夏季降水预估的可靠性,利用第六次耦合模式比较计划(Coupled Model Intercomparison Project Phase6,CMIP6)中的全球气候模式以及4个初值大样本的模拟结果,通过“完美模式”可靠性评估框架,对结合模式模拟性能和独立性的加权方案(Climate model Weighting by Independence and Performance,ClimWIP)中的约束变量及其空间尺度进行优选。结果发现将历史时期全球尺度的平均温度趋势作为约束变量比其他更小尺度约束变量得到的加权预估结果更可靠,且综合考虑历史时期全球平均温度趋势和降水指数区域气候态模拟能力约束的ClimWIP方案的预估结果最可靠。基于该最优可靠性的加权预估表明,在SSP5-8.5情景下,相较于历史参考期(1995—2014年),21世纪中期(2041—2060年)和末期(2081—2099年)中国东部区域夏季降水将分别增加6.84%和12.91%,强降水指数增大16.94%和28.66%。其中华北地区增加最为显著,21世纪末期夏季降水和强降水将分别增加19.09%和35.53%。相较于未加权方案(MME),最优预估方案增强了夏季降水的年际变率,未来旱涝的年际变化将更剧烈。同时减小了各区域预估降水的不确定性,并主要集中于预估的高值部分。21世纪中期,东北地区预估不确定性降低最大(40%);末期,华北和长江流域地区预估不确定性降低最大(约50%)。展开更多
基金Dr.X.L.Li at the China Meteorological Administration.This study was supported by grants from the National Natural Science Foundation of China(Nos.41575103 and 91637210).
文摘With an increase in model resolution,compact high-order numerical advection scheme can improve its effectiveness and competitiveness in oceanic modeling due to its high accuracy and scalability on massive-processor computers.To provide high-quality numerical ocean simulation on overset grids,we tried a novel formulation of the fourth-order multi-moment constrained finite volume scheme to simulate continuous and discontinuous problems in the Cartesian coordinate.Utilizing some degrees of freedom over each cell and derivatives at the cell center,we obtained a two-dimensional(2D)cubic polynomial from which point values on the extended overlap can achieve fourth-order accuracy.However,this interpolation causes a lack of conservation because the flux between the regions are no longer equal;thus,a flux correction is implemented to ensure conservation.A couple of numerical experiments are presented to evaluate the numerical scheme,which confirms its approximately fourth-order accuracy in conservative transportation on overset grid.The test cases reveal that the scheme is effective to suppress numerical oscillation in discontinuous problems,which may be powerful for salinity advection computing with a sharp gradient.
文摘为提高中国东部区域夏季降水预估的可靠性,利用第六次耦合模式比较计划(Coupled Model Intercomparison Project Phase6,CMIP6)中的全球气候模式以及4个初值大样本的模拟结果,通过“完美模式”可靠性评估框架,对结合模式模拟性能和独立性的加权方案(Climate model Weighting by Independence and Performance,ClimWIP)中的约束变量及其空间尺度进行优选。结果发现将历史时期全球尺度的平均温度趋势作为约束变量比其他更小尺度约束变量得到的加权预估结果更可靠,且综合考虑历史时期全球平均温度趋势和降水指数区域气候态模拟能力约束的ClimWIP方案的预估结果最可靠。基于该最优可靠性的加权预估表明,在SSP5-8.5情景下,相较于历史参考期(1995—2014年),21世纪中期(2041—2060年)和末期(2081—2099年)中国东部区域夏季降水将分别增加6.84%和12.91%,强降水指数增大16.94%和28.66%。其中华北地区增加最为显著,21世纪末期夏季降水和强降水将分别增加19.09%和35.53%。相较于未加权方案(MME),最优预估方案增强了夏季降水的年际变率,未来旱涝的年际变化将更剧烈。同时减小了各区域预估降水的不确定性,并主要集中于预估的高值部分。21世纪中期,东北地区预估不确定性降低最大(40%);末期,华北和长江流域地区预估不确定性降低最大(约50%)。
