南京大学：《大气环流》课程教学资源（课件讲稿）第四章 中纬度的经向环流系统（1/4）Ferrel cell，baroclinic eddies and the westerly jet

点金 第四章： 中纬度的经向环流系统 Ferrel cell,baroclinic eddies and the westerly jet Reference reading: Vallis Chapter 11.7;PO Chapter 7.5

第四章： 中纬度的经向环流系统 - Ferrel cell，baroclinic eddies and the westerly jet Reference reading: Vallis Chapter 11.7; PO Chapter 7.5

及图乐 Outline Review Observations The Ferrel Cell ■ Baroclinic eddies Review:baroclinic instability and baroclinic eddy life cycle Eddy-mean flow interaction Transformed Eulerian Mean equation Eddy-driven jet The energy cycle 授课教师：张洋3

授课教师：张洋 3 Outline n Observations n The Ferrel Cell n Baroclinic eddies n Review: baroclinic instability and baroclinic eddy life cycle n Eddy-mean flow interaction n Transformed Eulerian Mean equation n Eddy-driven jet n The energy cycle Review

Observations -Zonal mean fields Review Meridional wind(N,经向风) 可o, ANNUAL (m s- 0 -0.5 10 0.5 二0.25 DJF 8 0.25 25 2.5 0 0 0. 0.5 0.25 -3.0 0.25 -0.4 : 2.5 0.5 10 -0.5 80705605040 302010S010N20 3040 50 60 70N80

授课教师：张洋 4 Observations -Zonal mean fields http://www.adultpdf.com Created by Image To PDF trial version, to remove this mark, please register this software. n Meridional wind (v, 经向⻛) Review

Observations -Zonal mean fields Review Vertical velocity(垂直速度) ANNUAL 10-4mbs-1 GLOBE 0 NH SH 10 DJF 0 10 0 -0.8 10 2 8070S 6050403020105010N203040 50 60 70N -0.5005 5 JX/八丁A/Iμ·J\T

授课教师：张洋 5 n Vertical velocity (垂直速度) http://www.adultpdf.com Created by Image To PDF trial version, to remove this mark, please register this software. Observations -Zonal mean fields Review

Observations -Zonal mean fields Review Stream function(流函数) 0 ANNUAL 2 0 6 Ferre Hadley Cel =6 8 Ferre 3 10 02 20 GLOBE 6 Ferre Hadley Cell Ferrel s州 8 3 10 2 6 6 8 Ferre 8 Hadley Cell Ferre 3 6 10 8070S 6050 40 30 2010S 0 10N20 30 4050 6070N80-5

授课教师：张洋 6 n Stream function (流函数) http://www.adultpdf.com Created by Image To PDF trial version, to remove this mark, please register this software. Hadley Cell Hadley Cell Hadley Cell Ferrel Ferrel Ferrel Ferrel Ferrel Ferrel Observations -Zonal mean fields Review

Observations Review 200 Zonal winds 400 (U,纬向风) 600 800 Midlatitude Jet -25 Annual 100 or S.P. 60S 40S 20S E.Q. 20N 40N 60N N.P. Polar-front Jet Subtropical or 一J66 Eddy-driven Jet 200 (edy) 400 Surface westerly is 600 Eddy-driven Eddy-drivem always centered and Jet 800 Jet strongest at 50 degree south and north,which 100 S.P 60S 40S 20S E.Q. 20N 40N 60N N.P. is always considered Subtropical Jet as the center of the 200 eddy-driven jet.It is 400 also the centric Eddy-driven latitude of Ferrel cell. 600 Eddy-driven et 800 JJA 60S 40S 20S E.Q. 20N 40N 60N N.P

Observations -Zonal mean fields 授课教师：张洋 7 n Zonal winds (U, 纬向⻛) S.P. 60S 40S 20S E.Q. 20N 40N 60N N.P. 200 400 600 800 1000 5 5 5 5 5 5 5 10 10 10 10 10 10 15 15 15 15 15 20 20 20 25 25 25 0 0 0 0 0 0 −5 −5 −5 −2.5 −2.5 −2.5 −2.5 Pressure (hpa) S.P. 60S 40S 20S E.Q. 20N 40N 60N N.P. 200 400 600 800 1000 5 5 5 5 5 5 5 10 10 10 10 10 10 15 15 15 15 15 20 20 20 20 20 25 25 30 25 35 40 0 0 0 0 0 0 0 −5 −5 −5 −2.5 −2.5 −2.5 − Pressure (hpa) 2.5 S.P. 60S 40S 20S E.Q. 20N 40N 60N N.P. 200 400 600 800 1000 5 5 5 5 5 5 10 10 10 10 10 15 15 15 20 20 20 25 25 30 30 35 35 40 0 0 0 0 0 0 0 − −10 10 −5 −5 −5 −5 −2.5 −2.5 −2.5 −2.5 Pressure (hpa) Annual DJF JJA Subtropical Jet Subtropical Jet Eddy-driven Jet Eddy-driven Jet Eddy-driven Jet Eddy-driven Jet Midlatitude Jet or Polar-front Jet or Eddy-driven Jet Surface westerly is always centered and strongest at 50 degree south and north, which is always considered as the center of the eddy-driven jet. It is also the centric latitude of Ferrel cell. Review

Observations -Zonal mean fields Review Temperature(温度场) 310 -Annual 300 ---DJF --JJA 290 280 Strong temperature 言 270 gradient at midlatitudes, 260 with obvious seasonal 25 variation in the Northern S.P. 60S 40S 20S E.Q. 20N 40N 60N N.P. 270 Hemisphere compared to ·。Ahrual° that in the Southern ---DJF 260 -JJA Hemisphere. 250 名 240 230 S.P 60S 40S 20S E.Q. 20N 40N 60N N.P. 授课教师：张洋8

授课教师：张洋 8 \ n Temperature (温度场) S.P. 60S 40S 20S E.Q. 20N 40N 60N N.P. 250 260 270 280 290 300 310 Surface air temperature (K) Annual DJF JJA S.P. 60S 40S 20S E.Q. 20N 40N 60N N.P. 230 240 250 260 270 Temp. (K) at 500 hpa Annual DJF JJA Strong temperature gradient at midlatitudes, with obvious seasonal variation in the Northern Hemisphere compared to that in the Southern Hemisphere. Observations -Zonal mean fields Review

及愈象 Observations Eddy fields Review Strong eddy activity 1992010100 The British Atmospheric Data Centre(BADC) www.badc.nerc.ac.uk/data/claus (infra-red) 授课教师：张洋9

9 Strong eddy activity The British Atmospheric Data Centre (BADC) www.badc.nerc.ac.uk/data/claus (infra-red) 授课教师：张洋 Observations - Eddy fields Review

Observations Eddy fields Review Strong baroclinic eddy activity LR~(1000km) Synoptic time scale(2-8 days) 1992010100 ABI [(A+A')(B+B)】=[AB]+AB] [(A+A*)([B]+B*)】+AB] [A][B]+[A*B*]+A'B] A=A+A*+A 授课教师：张洋10

[AB]=[(A¯ + A0 )(B¯ + B0 )] = [A¯B¯]+[A0 B0 ] = [([A¯] + A¯⇤)([B¯] + B¯⇤)] + [A0 B0 ] = ¯[A] ¯[B] + [A¯⇤B¯⇤] + [A0 B0 ] A = [A¯] + A¯⇤ + A 0 10 \ 授课教师：张洋 Strong baroclinic eddy activity LR ￾ O(1000km) Synoptic time scale (2-8 days) Observations - Eddy fields Review

Observations Eddy fields 10 K】 ANNUAL ■Kinetic energy: 10m2s-2150- -50 50 30 20 一GLOBE A=A+A*+A 一NH ---5H 10 K TE 5 20 K=KM+KSE十KTE 10 also the centric latitude of Ferrel CeHl, 8 KM=I园2+P) 10 the latitude with strong baroclinicity KsE KE=)2+网 30 -20 20 10 also the location of jet core 1o22 807056050403020105010N203040506070N0102030 授课教师：张洋11

11 \ 授课教师：张洋 http://www.adultpdf.com Created by Image To PDF trial version, to remove this mark, please register this software. n Kinetic energy: A = [A¯] + A¯⇤ + A0 KM = 1 2 ([¯u] 2 + [¯v] 2) KSE = 1 2 [¯u⇤2 + ¯v⇤2] KTE = 1 2 [u 02 + v 02] K = KM + KSE + KT E also the location of jet core also the centric latitude of Ferrel Cell, the latitude with strong baroclinicity Observations - Eddy fields