南京大学：《大气环流》课程教学资源（课件讲稿）第五章 大气环流中的纬向环流系统（5.2.1）Monsoon Circulation

及金乐 第五章： 大气环流中的纬向环流系统 5.2 Monsoon Circulation 授课教师：张洋 2022.12.04

第五章： 大气环流中的纬向环流系统 5.2 Monsoon Circulation 授课教师：张洋 2022. 12. 04

及图乐 Outline Introduction Features of monsoon circulation: an Indian monsoon example Monsoon dynamics The land-sea contrast The role of Orography,Tibet Plateau Some GCM results On the East Asian monsoon 授课教师：张洋2

授课教师：张洋 2 Outline n Introduction n Features of monsoon circulation: an Indian monsoon example n Monsoon dynamics n The land-sea contrast n The role of Orography, Tibet Plateau n Some GCM results n On the East Asian monsoon

Introduction The definition of monsoon:a dramatic seasonal reversal of the low-level prevailing winds,precipitation and atmospheric circulation. The major monsoon systems of the world: Asian monsoon ■South Asian monsoon East Asian monsoon Australian (Indo-Australian)monsoon ■Vest African monsoon North and South American monsoon(controversial) 授课教师：张洋3

授课教师：张洋 3 Introduction n The definition of monsoon: a dramatic seasonal reversal of the low-level prevailing winds, precipitation and atmospheric circulation. n The major monsoon systems of the world: n Asian monsoon n South Asian monsoon n East Asian monsoon n Australian (Indo-Australian) monsoon n West African monsoon n North and South American monsoon (controversial)

Introduction Geographical Extent of the Global Surface Monsoons ai时01m特1南0nm06Mw风rdG与64ors 5C利 65%of world's population lives within monsoon; Monsoon precipitation is crucial to the life,food 39 35 production,economy et al in these regions; 515 Proper forecasting of location 0 G03 160 and quantity of precipitation The red,green,and blue areas indicale the tropical,subtropical,and temperate-frigid monsoons is crucial to theses regions. respoctively.The red anc blue thick lincs roprescnt the ITCZ in summer and winkr,respodtively. (Li,J..and Q.Zeng.2C05) 授课教师：张洋4

授课教师：张洋 4 Introduction n 65% of world’s population lives within monsoon; n Monsoon precipitation is crucial to the life, food production, economy et al in these regions; n Proper forecasting of location and quantity of precipitation is crucial to theses regions

Introduction The formation of monsoon climate is closely related to the seasonal variation of the solar forcing and the seasonal migration of the planetary scale flow. taH1时ah0nm0%minwecand d的96 SCN 65%of world's population lives within monsoon; Monsoon precipitation is crucial to the life,food 39 35 production,economy et al in these regions; 505 Proper forecasting of location DeV 0 GOE 160 and quantity of precipitation The red,green,and blue areas indicale the tropical,subtropical,and temperate-frigid monsoons is crucial to theses regions. respoctively.The red anc blue thick lincs roprescnt the ITCZ in summer and winkr,respodtively. (Li,J..and Q.Zeng.2C05) 授课教师：张洋5

授课教师：张洋 5 Introduction n 65% of world’s population lives within monsoon; n Monsoon precipitation is crucial to the life, food production, economy et al in these regions; n Proper forecasting of location and quantity of precipitation is crucial to theses regions. The formation of monsoon climate is closely related to the seasonal variation of the solar forcing and the seasonal migration of the planetary scale flow

Latent heat and water vapor Seasonal variation:strongest in the subtropics, monsoon regions 90N △ (g kg JAN-JUL 60 30 -81 EQ es≈6.11xe(3-) 30 LH=Lq Co 60 9=RH×q* b L1上上山十十十十十↓L上L山上L上 180 120 60W 0 60E 120 180 授课教师：张洋6

授课教师：张洋 6 Latent heat and water vapor LH = Lq es ⇠ = 6.11 ⇥ e L Rv ( 1 273 ￾ 1 T ) q = RH ⇥ q⇤ http://www.adultpdf.com Created by Image To PDF trial version, to remove this mark, please register this software. n Seasonal variation: strongest in the subtropics, monsoon regions

及图 Features of monsoonal circulation: -an Indian monsoon example TRMM Merged Precip Jul 2003 (mm/d) 0 481216 20+ TRMM Merged Precip Jan 2003 (mm/d) 0 812 16 20+ 授课教师：张洋7

授课教师：张洋 7 Features of monsoonal circulation: -an Indian monsoon example

Features of monsoonal circulation: -an Indian monsoon example DJF MAM 30 30 The seasons of winter 30 -30 )306090120150 0306090120150 and summer might be JJA SON better described as dry 30 30 and moist seasons -30 -301 30 60 90 120 150 0 30 60 90 120 150 Figure 1.11 Climatological mean rainfall rate for the four seasons.The coutour interval is 2.5 mmday;heavy shading denotes rainfall greater thau 5-10 mmday1.(from Clift and Plumb,2008) 授课教师：张洋8

授课教师：张洋 8 Features of monsoonal circulation: -an Indian monsoon example The seasons of winter and summer might be better described as dry and moist seasons. (from Clift and Plumb, 2008)

Features of monsoonal circulation: -an Indian monsoon example 10ms1 DJF MAM 30 30 30 30 0 306090120150 30 60 90120150 An obvious 101 SON reverse of the 30 30 prevailing winds -301 306090120150 0 3060 90 120150 Fignre 1.12 Climatological mean low level (850h Pa)winds for the four seasons. The scale for the wind arrows is shown at the top left of each plot.The heavy lines mark regions of seasonal mean rainfall in excess of 7.5 mm day 1. (from Clift and Plumb,2008) 授课教师：张洋 9

授课教师：张洋 9 Features of monsoonal circulation: -an Indian monsoon example An obvious reverse of the prevailing winds Somali Jet (from Clift and Plumb, 2008)

Features of monsoonal circulation: a xample 42N Accompanied is the reverse of whole atmospheric circulation. Cross equator meridional overturning circulation. 18S 30E 20E+93 150E NCEP Long Te'm Daly Mean Flow for July 1.50-15CE Maxlmum Vector 100--- b 42N 200--2X11、、1、、 300-221+1T个1 400 500 600·1344 700 800 90 002 -Tr*个 -30 -20 -10010 203040 18 Lat tude 30E .200E+0 150E Maxlmum Vector Figure 8.29:Observed 850 mb wind vectors for a)January,and b)July. 授课教师：张洋10

授课教师：张洋 10 Features of monsoonal circulation: -an Indian monsoon example The onset of the summer monsoon brings cooler surface temperatures to India and other areas that receive monsoonal precipitation, due to the increase in clouds as well as the increase in soil moisture that accompanies the precipitation. The data shows, as one might expect, that the lowest surface air temperatures in the monsoon region occur at the highest elevations. There is a large area of low (less than 280 K) surface air temperature on the Tibetan Plateau, and a large area of high (greater than 305 K) surface air temperatures on the Arabian Peninsula. From an agricultural standpoint, the beginning of the precipitation associated with the Asian summer monsoon is probably one of the most anticipated events in the world. The onset of the monsoon is generally defined as the beginning of consistent rainfall of the monsoon season. Figure 8.29: Observed 850 mb wind vectors for a) January, and b) July. a b Revised Tuesday, May 26, 2009 50 An Introduction to the General Circulation of the Atmosphere Cross equator meridional overturning circulation. Accompanied is the reverse of whole atmospheric circulation