基于两套模式的大集合试验结果,评估了气候内部自然变率对热带辐合带(ITCZ,Intertropical convergence zone)未来南北移动的影响。研究发现,模式间ITCZ的移动差异源自中高纬度的外强迫模拟差异,而气候内部变率主要通过热带过程调控ITCZ...基于两套模式的大集合试验结果,评估了气候内部自然变率对热带辐合带(ITCZ,Intertropical convergence zone)未来南北移动的影响。研究发现,模式间ITCZ的移动差异源自中高纬度的外强迫模拟差异,而气候内部变率主要通过热带过程调控ITCZ的位置变化。在通用地球系统模式大集合(Community Earth System Model Large Ensemble,CESM-LE)试验中,厄尔尼诺-南方涛动(El Nino-Southern Oscillation,ENSO)振幅变化的自然变率会通过中等和极端厄尔尼诺降水的非线性信号调制ITCZ的移动幅度,而在MPI-GE(the Max Planck Institute Great Ensemble)试验中,ITCZ的位置变化主要与大西洋海温梯度信号异常有关,相较而言ENSO振幅对ITCZ的影响很有限。总体而言,全球变暖背景下由于内部自然变率引起的ITCZ南北移动不确定性幅度能解释未来预估模式间的差异约为20%,但对ITCZ移动的模拟不确定性有贡献。展开更多
利用实况资料和小波分析方法研究了赤道平流层中下层纬向风准2 a振荡(简称QBO)周期变化与行星运动之间的联系,结果表明,QBO周期以火星冲日(25.68月)周期为基准,时而变长,时而变短。当地球、土星、天王星3星一线时,火星冲日月份30 h Pa...利用实况资料和小波分析方法研究了赤道平流层中下层纬向风准2 a振荡(简称QBO)周期变化与行星运动之间的联系,结果表明,QBO周期以火星冲日(25.68月)周期为基准,时而变长,时而变短。当地球、土星、天王星3星一线时,火星冲日月份30 h Pa纬向风由东风向西风转换;而3星成直角时,则从西风向东风的转换。QBO周期变化与木星冲日时的视赤纬存在明显的对应关系。当木星冲日视赤纬达到正极值时(此时为北半球的冬季),QBO周期达到最大;当木星冲日视赤纬达到负极值时(此时为北半球的夏季),QBO周期达到最小。QBO周期与木星冲日视赤纬之间的相关系数高达0.496,并通过0.001显著性检验。QBO强度与周期、木星冲日时的视赤纬呈现反相变化,即QBO强度的强(弱),对应于QBO周期的短(长)。木星冲日负(正)视赤纬,在过去60 a中,QBO的强度总体呈现增加的趋势,与天王星的视赤纬减小存在一定的联系。展开更多
The commollly used objective analysis scheme(Scheme-A) for the analysis Of wind and geopotential height smoothen the divergent component of the wind which is rather important in the tropics,specifically over convectiv...The commollly used objective analysis scheme(Scheme-A) for the analysis Of wind and geopotential height smoothen the divergent component of the wind which is rather important in the tropics,specifically over convective regions.To overcome this deficiellcy, a new analysis SCheme in which divergent component is included in the statistical model of the wind forecast errors,has been proposed by Daley(1985).Following this scheme,a new set of correlahon functions of forecast errors for the indian region during monsoon season which are suitable for analysing the tropical wind are obtained.This analysis scheme(Scheme--B) as well as Scheme-A were used to make analyses for the period from 4 July to & July 1979(12 GMT) at 850,700 and 200 hpa levels over an area bounded by l.875'N to 39.375'N and 41.250'E to 108.750'E and subsequently divergent component,velocity potential are computed for both schemes.Results from both these schemes show that in the monsoon depression region the velocity potential and divergence have increased in the later case(Scheme-B).This suggests that the divergent component has been enhanced in Scheme-B and that the objechve of this study is realized to some extent.展开更多
文摘基于两套模式的大集合试验结果,评估了气候内部自然变率对热带辐合带(ITCZ,Intertropical convergence zone)未来南北移动的影响。研究发现,模式间ITCZ的移动差异源自中高纬度的外强迫模拟差异,而气候内部变率主要通过热带过程调控ITCZ的位置变化。在通用地球系统模式大集合(Community Earth System Model Large Ensemble,CESM-LE)试验中,厄尔尼诺-南方涛动(El Nino-Southern Oscillation,ENSO)振幅变化的自然变率会通过中等和极端厄尔尼诺降水的非线性信号调制ITCZ的移动幅度,而在MPI-GE(the Max Planck Institute Great Ensemble)试验中,ITCZ的位置变化主要与大西洋海温梯度信号异常有关,相较而言ENSO振幅对ITCZ的影响很有限。总体而言,全球变暖背景下由于内部自然变率引起的ITCZ南北移动不确定性幅度能解释未来预估模式间的差异约为20%,但对ITCZ移动的模拟不确定性有贡献。
文摘利用实况资料和小波分析方法研究了赤道平流层中下层纬向风准2 a振荡(简称QBO)周期变化与行星运动之间的联系,结果表明,QBO周期以火星冲日(25.68月)周期为基准,时而变长,时而变短。当地球、土星、天王星3星一线时,火星冲日月份30 h Pa纬向风由东风向西风转换;而3星成直角时,则从西风向东风的转换。QBO周期变化与木星冲日时的视赤纬存在明显的对应关系。当木星冲日视赤纬达到正极值时(此时为北半球的冬季),QBO周期达到最大;当木星冲日视赤纬达到负极值时(此时为北半球的夏季),QBO周期达到最小。QBO周期与木星冲日视赤纬之间的相关系数高达0.496,并通过0.001显著性检验。QBO强度与周期、木星冲日时的视赤纬呈现反相变化,即QBO强度的强(弱),对应于QBO周期的短(长)。木星冲日负(正)视赤纬,在过去60 a中,QBO的强度总体呈现增加的趋势,与天王星的视赤纬减小存在一定的联系。
文摘The commollly used objective analysis scheme(Scheme-A) for the analysis Of wind and geopotential height smoothen the divergent component of the wind which is rather important in the tropics,specifically over convective regions.To overcome this deficiellcy, a new analysis SCheme in which divergent component is included in the statistical model of the wind forecast errors,has been proposed by Daley(1985).Following this scheme,a new set of correlahon functions of forecast errors for the indian region during monsoon season which are suitable for analysing the tropical wind are obtained.This analysis scheme(Scheme--B) as well as Scheme-A were used to make analyses for the period from 4 July to & July 1979(12 GMT) at 850,700 and 200 hpa levels over an area bounded by l.875'N to 39.375'N and 41.250'E to 108.750'E and subsequently divergent component,velocity potential are computed for both schemes.Results from both these schemes show that in the monsoon depression region the velocity potential and divergence have increased in the later case(Scheme-B).This suggests that the divergent component has been enhanced in Scheme-B and that the objechve of this study is realized to some extent.
