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Lecture 7: Atmospheric General Circulation

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Lecture 7: Atmospheric General Circulation The climatological mean circulation Deviations from the climatological mean Synthesis: momentum and the jets Lecture 7: Atmospheric General Circulation Jonathon S. Wright [email protected] 11 April 2017 The climatological mean circulation Deviations from the climatological mean Synthesis: momentum and the jets The climatological mean circulation Zonal mean energy transport Zonal mean energy budget of the atmosphere The climatological mean and seasonal cycle Deviations from the climatological mean Transient and quasi-stationary eddies Eddy fluxes of heat, momentum, and moisture Eddies in the atmospheric circulation Synthesis: momentum and the jets Vorticity and Rossby waves Momentum fluxes Isentropic overturning circulation The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle 400 Outgoing longwave radiation 350 net energy loss in Incoming solar radiation ] 2 − 300 the extratropics m 250 W [ x 200 u l f y 150 net energy gain g r e n 100 E in the tropics 50 0 90°S 60°S 30°S 0° 30°N 60°N 90°N 6 4 2 0 2 Energy flux [PW] 4 JRA-55 6 90°S 60°S 30°S 0° 30°N 60°N 90°N data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle 400 Outgoing longwave radiation 350 Incoming solar radiation ] 2 − 300 m 250 W [ x 200 u l f y 150 g r e n 100 E 50 0 90°S 60°S 30°S 0° 30°N 60°N 90°N 6 Northward atmospheric energy transport 4 Northward ocean energy transport Total northward energy transport 2 0 2 Energy flux [PW] 4 JRA-55 6 90°S 60°S 30°S 0° 30°N 60°N 90°N data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle 400 Outgoing longwave radiation 350 Incoming solar radiation ] 2 − 300 m 250 W [ x 200 u l f y 150 g r e n 100 E 50 0 90°S 60°S 30°S 0° 30°N 60°N 90°N 6 Northward atmospheric energy transport 4 Northward ocean energy transport Total northward energy transport 2 0 2 Energy flux [PW] 4 CFSR 6 90°S 60°S 30°S 0° 30°N 60°N 90°N data from CFSR The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Energy budget of an atmospheric column @E a = R + LP + SH + TR @t net 300 LP SH Radiation Transport 200 latent heating ] 2 − m transport 100 W [ x u l f sensible heating y g r 0 e n E radiative cooling 100 JRA-55 200 90°S 60°S 30°S 0° 30°N 60°N 90°N data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Energy budget of an atmospheric column @E a = R + LP + SH + TR @t net 300 LP SH Radiation Transport 200 latent heating ] 2 − m transport 100 W [ x u l f sensible heating y g r 0 e n E radiative cooling 100 CFSR 200 90°S 60°S 30°S 0° 30°N 60°N 90°N data from CFSR The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle The climatological mean 1 Z τ time mean: x = xdt τ 0 climatological zonal mean: [x] 1 Z 2π zonal mean: [x] = xdλ 2π 0 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Zonal mean zonal wind subtropical jets 100 200 300 400 500 600 Pressure [hPa] 700 800 tropical midlatitude 900 easterlies westerlies 1000 90°S 60°S 30°S 0° 30°N 60°N 90°N 30 24 18 12 6 0 6 12 18 24 30 1 extratropical jet Zonal wind [m s− ] data from JRA-55 (storm track) The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Zonal mean zonal wind: energy and momentum transfer perspectives energy budget angular momentum budget Q 4 (1 − α) = σT M = (uearth + u) a cos ' 4 e pole Energy loss Implied energy W Implied momentum transport transport Loss of angular momentum Energy gain Gain of angular E momentum The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Zonal mean zonal wind 100−15 m s−1 < [u] < 35 m s−1 200 300 400 500 600 Pressure [hPa] 700 800 900 1000 90°S 60°S 30°S 0° 30°N 60°N 90°N 30 24 18 12 6 0 6 12 18 24 30 1 Zonal wind [m s− ] data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Zonal mean uearth 100 200 300 400 500 600 u = Ωa cos # u, particularly in the tropics Pressure [hPa] earth 700 800 900 1000 90°S 60°S 30°S 0° 30°N 60°N 90°N 0 50 100 150 200 250 300 350 400 450 500 1 Angular velocity [m s− ] data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Zonal mean angular velocity (uearth + u) 100 200 300 400 500 600 Pressure [hPa] 700 800 900 1000 90°S 60°S 30°S 0° 30°N 60°N 90°N 0 50 100 150 200 250 300 350 400 450 500 1 Angular velocity [m s− ] data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle The mean meridional circulation mass streamfunction 2πa cos ' Z p ΨM = [v] dp g 0 The mass flow between any two streamlines is equal to the difference between the streamlines g @Ψ −g @Ψ [v] = M [w] = M 2πa cos ' @p 2πa2 cos ' @' The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Meridional mass streamfunction 100 200 300 400 500 600 Pressure [hPa] 700 800 900 contours streamfunction 1000 90°S 60°S 30°S 0° 30°N 60°N 90°N -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 2 1 Vertical wind [ 10− Pa s− ] × data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle contours streamfunction data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Northward heat flux by mean meridional circulation 100 200 300 400 500 600 Pressure [hPa] 700 800 900 contours streamfunction 1000 90°S 60°S 30°S 0° 30°N 60°N 90°N 15 10 5 0 5 10 15 1 Heat flux [K m s− ] data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Northward water vapor flux by mean meridional circulation 100 200 300 400 500 600 Pressure [hPa] 700 800 900 contours streamfunction 1000 90°S 60°S 30°S 0° 30°N 60°N 90°N 5 4 3 2 1 0 1 2 3 4 5 1 1 Water vapor flux [g kg− m s− ] data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle Northward momentum flux by mean meridional circulation 100 200 300 400 500 600 Pressure [hPa] 700 800 900 contours streamfunction 1000 90°S 60°S 30°S 0° 30°N 60°N 90°N 30 20 10 0 10 20 30 8 3 2 Zonal momentum flux [ 10 m s− ] × data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological mean and seasonal cycle The MMC and energy transport Potential energy: PE = gz Vertical Energy Distribution 100 100 100 200 200 200 300 300 300 400 400 400 500 500 500 PE 600 600 600 Pressure [hPa] 700 700 700 800 800 800 900 900 900 contours streamfunction 1000 1000 1000 30°S 20°S 10°S 0° 0 1 2 3 4 5 0° 30°N 60°N 90°N 5 1 Energy [ 10 J kg− ] × data from JRA-55 The climatological mean circulation Zonal mean energy transport Deviations from the climatological mean Zonal mean energy budget of the atmosphere Synthesis: momentum and the jets The climatological
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