Dynamical role of the Rocky Mountain controlled by East Asian topographies in modulating the tropospheric westerly jet in northern winter
|
摘要
本文通过数值模拟,研究了有无东亚地形存在时,落基山地形作用对冬季北半球副热带西风急流的影响,分析了东亚大地形对落基山地形的调制作用。结果表明,东亚地形的存在能够完全抑制落基山地形对太平洋副热带急流的加强作用,使得落基山地形作用仅能加强其下游的大西洋副热带急流。主要原因是东亚大地形可抑制落基山地形北侧反气旋环流的发展,进而抑制中纬度太平洋地区经向温度梯度的加强。该结果有助于我们进一步理解北半球大地形强迫作用,及其相互调制作用对对流层天气和环流结构的影响。
Large-scale mountains like Asian topographies and the Rocky Mountains have important influences on subtropical jet streams(STJs) over downstream regions in winter. The dynamical role of the Rocky Mountains in modulating STJs with and without the existence of East Asian(EA) topographies in northern winter is investigated via numerical experiments. In agreement with previous studies, the Rocky Mountains(topographic forcing), with the existence of EA topographies, can only strengthen the STJ from the east coast of North America to the western Atlantic region. The independent role of the Rocky Mountains, however, strengthens the STJ over not only the east coast of North America but also over Pacific regions. It is found that the existence of EA topographies can dramatically strengthen the EA trough, as well as a downstream ridge which, in the upstream of the Rocky Mountains, acts to partly cancel out the strengthening of the anticyclone to the north of the Rocky Mountains and the northward warm air transport in the high latitudes of Pacific regions due to the Rocky Mountains' forcing alone. Such circulation changes effectively weaken the Rocky Mountains–forced strengthening of the meridional temperature gradient in the midlatitude North Pacific, and thus the STJ there.Therefore, EA topographies are of great importance in modulating the role of the Rocky Mountains as a dynamical forcing of STJ variability.
Large-scale mountains like Asian topographies and the Rocky Mountains have important influences on subtropical jet streams(STJs) over downstream regions in winter. The dynamical role of the Rocky Mountains in modulating STJs with and without the existence of East Asian(EA) topographies in northern winter is investigated via numerical experiments. In agreement with previous studies, the Rocky Mountains(topographic forcing), with the existence of EA topographies, can only strengthen the STJ from the east coast of North America to the western Atlantic region. The independent role of the Rocky Mountains, however, strengthens the STJ over not only the east coast of North America but also over Pacific regions. It is found that the existence of EA topographies can dramatically strengthen the EA trough, as well as a downstream ridge which, in the upstream of the Rocky Mountains, acts to partly cancel out the strengthening of the anticyclone to the north of the Rocky Mountains and the northward warm air transport in the high latitudes of Pacific regions due to the Rocky Mountains' forcing alone. Such circulation changes effectively weaken the Rocky Mountains–forced strengthening of the meridional temperature gradient in the midlatitude North Pacific, and thus the STJ there.Therefore, EA topographies are of great importance in modulating the role of the Rocky Mountains as a dynamical forcing of STJ variability.
引文
Ambrizzi,T.,B.J.Hoskins,and H.Hsu.1995.“Rossby Wave Propagation and Teleconnection Patterns in the Austra Winter.”Journal of the Atmospheric Sciences 52:3661-3672doi:10.1175/1520-0469(1995)052<3661:RWPATP>2.0.CO;2.
Bolin,B.1950.“On the Influence of the Earth’s Orography on the General Character of the Westerlies.”Tellus 2:184-195doi:10.3402/tellusa.v2i3.8547.
Brayshaw,D.,B.J.Hoskins,and M.Blackburn.2008.“The Storm-Track Response to Idealized SST Perturbations in an Aquaplanet GCM.”Journal of the Atmospheric Sciences 652842-2860.doi:10.1175/2008JAS2657.1.
Brayshaw,D.,B.J.Hoskins,and M.Blackburn.2009.“The Basic Ingredients of the North Atlantic Storm Track.Part I:Land-Sea Contrast and Orography.”Journal of the Atmospheric Sciences66:2539-2558.doi:10.1175/2009JAS3078.1.
Held,I.M.1983.“Stationary and Quasi-Stationary Eddies in the Extratropical Troposphere:Theory.”Large-Scale Dynamica Processes in the Atmosphere 127-168.http://citeseerx.ist psu.edu/viewdoc/download?doi=10.1.1.226.5733&rep=rep1&type=pdf.
Held,I.M.,and A.Y.Hou.1980.“Nonlinear Axially Symmetric Circulations in a Nearly Inviscid Atmosphere.”Journal of the Atmospheric Sciences 37:515-533.doi:10.1175/1520-0469-(1980)037<0515:NASCIA>2.0.CO;2.
Hunt,B.G.1979.“The Influence of the Earth’s Rotation Rate on the General Circulation of the Atmosphere.”Journal of the Atmospheric Sciences 36:1392-1408.doi:10.1175/1520-0469(1979)036<1392:TIOTER>2.0.CO;2.
Langford,A.O.1999.“Stratosphere-Troposphere Exchange at the Subtropical Jet:Contribution to the Tropospheric Ozone Budget at Midlatitudes.”Geophysical Research Letters 26:2449-2452.doi:10.1029/1999GL900556.
Lin,B.-D.1982.“The Behavior of Winter Stationary Planetary Waves Forced by Topography and Diabatic Heating.”Journal of the Atmospheric Sciences 39:1206-1226doi:10.1175/1520-0469(1982)039<1206:TBOWSP>2.0.CO;2.
Marsh,D.R.,M.J.Mills,D.E.Kinnison,J.-F.Lamarque,N.Calvo and L.M.Polvani.2013.“Climate Change from 1850 to2005 Simulated in CESM1(WACCM).”Journal of Climate26:7372-7391.doi:10.1175/JCLI-D-12-00558.1.
Nakamura,H.,T.Sampe,A.Goto,W.Ohfuchi,and S.Xie.2008“On the Importance of Midlatitude Oceanic Frontal Zones for the Mean State and Dominant Variability in the Tropospheric Circulation.”Geophysical Research Letters 35doi.doi:10.1029/2008GL034010.
Ren,X.,X.Yang,T.Zhou,and J.Fang.2011.“Diagnostic Comparison of Wintertime East Asian Subtropical Jet and Polar-Front Jet:Large-Scale Characteristics and Transient Eddy Activities.”Acta Meteorologica Sinica 25:21-33doi:10.1007/s13351-011-0002-2.
Sato,T.2009.“Influences of Subtropical Jet and Tibetan Plateau on Precipitation Pattern in Asia:Insights from Regional Climate Modeling.”Quaternary International 194148-158.doi:10.1016/j.quaint.2008.07.008.
Shi,Z.,X.Liu,Y.Liu,Y.Sha,and T.Xu.2015.“Impact of Mongolian Plateau versus Tibetan Plateau on the Westerly Jet over North Pacific Ocean.”Climate Dynamics 443067-3076.doi:10.1007/s00382-014-2217-2.
Wallace,J.M.,and D.S.Gutzler.1981.“Teleconnections in the Geopotential Height Field during the Northern Hemisphere Winter.”Monthly Weather Review 109:784-812doi:10.1175/1520-0493(1981)109<0784:TITGHF>2.0.CO;2.
White,R.H.,D.S.Battisti,and G.H.Roe.2017.“Mongolian Mountains Matter Most:Impacts of the Latitude and Height of Asian Orography on Pacific Wintertime Atmospheric Circulation.”Journal of Climate 30:4065-4082doi:10.1175/JCLI-D-16-0401.1.
Wu,G.,Y.Liu,Q.Zhang,A.Duan,T.Wang,R.Wan,W.Li Z.Wang,X.Liang,and X.Liu.2007.“The Influence of Mechanical and Thermal Forcing by the Tibetan Plateau on Asian Climate.”Journal of Hydrometeorology 8770-789.doi:10.1175/JHM609.1.
Yanai,M.,G.X.Wu,and B.Wang.2006.“Effects of the Tibetan Plateau.”In The Asian Monsoon.doi:10.1007/3-540-37722-0_13.
Yoshikane,T.,F.Kimura,and S.Emori.2001.“Numerical Study on the Baiu Front Genesis by Heating Contrast between Land and Ocean.”Journal of the Meteorological Society of Japan 79:671-686.doi:10.2151/jmsj.79.671.
Bolin,B.1950.“On the Influence of the Earth’s Orography on the General Character of the Westerlies.”Tellus 2:184-195doi:10.3402/tellusa.v2i3.8547.
Brayshaw,D.,B.J.Hoskins,and M.Blackburn.2008.“The Storm-Track Response to Idealized SST Perturbations in an Aquaplanet GCM.”Journal of the Atmospheric Sciences 652842-2860.doi:10.1175/2008JAS2657.1.
Brayshaw,D.,B.J.Hoskins,and M.Blackburn.2009.“The Basic Ingredients of the North Atlantic Storm Track.Part I:Land-Sea Contrast and Orography.”Journal of the Atmospheric Sciences66:2539-2558.doi:10.1175/2009JAS3078.1.
Held,I.M.1983.“Stationary and Quasi-Stationary Eddies in the Extratropical Troposphere:Theory.”Large-Scale Dynamica Processes in the Atmosphere 127-168.http://citeseerx.ist psu.edu/viewdoc/download?doi=10.1.1.226.5733&rep=rep1&type=pdf.
Held,I.M.,and A.Y.Hou.1980.“Nonlinear Axially Symmetric Circulations in a Nearly Inviscid Atmosphere.”Journal of the Atmospheric Sciences 37:515-533.doi:10.1175/1520-0469-(1980)037<0515:NASCIA>2.0.CO;2.
Hunt,B.G.1979.“The Influence of the Earth’s Rotation Rate on the General Circulation of the Atmosphere.”Journal of the Atmospheric Sciences 36:1392-1408.doi:10.1175/1520-0469(1979)036<1392:TIOTER>2.0.CO;2.
Langford,A.O.1999.“Stratosphere-Troposphere Exchange at the Subtropical Jet:Contribution to the Tropospheric Ozone Budget at Midlatitudes.”Geophysical Research Letters 26:2449-2452.doi:10.1029/1999GL900556.
Lin,B.-D.1982.“The Behavior of Winter Stationary Planetary Waves Forced by Topography and Diabatic Heating.”Journal of the Atmospheric Sciences 39:1206-1226doi:10.1175/1520-0469(1982)039<1206:TBOWSP>2.0.CO;2.
Marsh,D.R.,M.J.Mills,D.E.Kinnison,J.-F.Lamarque,N.Calvo and L.M.Polvani.2013.“Climate Change from 1850 to2005 Simulated in CESM1(WACCM).”Journal of Climate26:7372-7391.doi:10.1175/JCLI-D-12-00558.1.
Nakamura,H.,T.Sampe,A.Goto,W.Ohfuchi,and S.Xie.2008“On the Importance of Midlatitude Oceanic Frontal Zones for the Mean State and Dominant Variability in the Tropospheric Circulation.”Geophysical Research Letters 35doi.doi:10.1029/2008GL034010.
Ren,X.,X.Yang,T.Zhou,and J.Fang.2011.“Diagnostic Comparison of Wintertime East Asian Subtropical Jet and Polar-Front Jet:Large-Scale Characteristics and Transient Eddy Activities.”Acta Meteorologica Sinica 25:21-33doi:10.1007/s13351-011-0002-2.
Sato,T.2009.“Influences of Subtropical Jet and Tibetan Plateau on Precipitation Pattern in Asia:Insights from Regional Climate Modeling.”Quaternary International 194148-158.doi:10.1016/j.quaint.2008.07.008.
Shi,Z.,X.Liu,Y.Liu,Y.Sha,and T.Xu.2015.“Impact of Mongolian Plateau versus Tibetan Plateau on the Westerly Jet over North Pacific Ocean.”Climate Dynamics 443067-3076.doi:10.1007/s00382-014-2217-2.
Wallace,J.M.,and D.S.Gutzler.1981.“Teleconnections in the Geopotential Height Field during the Northern Hemisphere Winter.”Monthly Weather Review 109:784-812doi:10.1175/1520-0493(1981)109<0784:TITGHF>2.0.CO;2.
White,R.H.,D.S.Battisti,and G.H.Roe.2017.“Mongolian Mountains Matter Most:Impacts of the Latitude and Height of Asian Orography on Pacific Wintertime Atmospheric Circulation.”Journal of Climate 30:4065-4082doi:10.1175/JCLI-D-16-0401.1.
Wu,G.,Y.Liu,Q.Zhang,A.Duan,T.Wang,R.Wan,W.Li Z.Wang,X.Liang,and X.Liu.2007.“The Influence of Mechanical and Thermal Forcing by the Tibetan Plateau on Asian Climate.”Journal of Hydrometeorology 8770-789.doi:10.1175/JHM609.1.
Yanai,M.,G.X.Wu,and B.Wang.2006.“Effects of the Tibetan Plateau.”In The Asian Monsoon.doi:10.1007/3-540-37722-0_13.
Yoshikane,T.,F.Kimura,and S.Emori.2001.“Numerical Study on the Baiu Front Genesis by Heating Contrast between Land and Ocean.”Journal of the Meteorological Society of Japan 79:671-686.doi:10.2151/jmsj.79.671.