Impact of the Climate Change on the Asian Monsoon System: the common scientific issue confronted by China and India

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1 Impact of the Climate Change on the Asian Monsoon System: the common scientific issue confronted by China and India Ding Yihui National Climate Center, China Meteorological Administration,

2 Outline 1. Weakening of the Asian summer monsoon and its consequences in China 2. Inter-decadal variation of snow over the Tibetan Plateau in preceding winter and spring and its impact on the Asian summer monsoon. 3. Projection of future Asian summer monsoon and precipitation 4. Common scientific issues between China and India: monsoon, glacier melting and aerosol effects

3 1. Weakening of the Asian summer monsoon and its consequences in China

4 Variation of East Asian monsoon index ( ) (IPCC,2007 IPCC,2007)

5 (a) (b) (c) Patterns of rainfall departure percentage for summer (JJA) (%) averaged for (a), for (b) and for (c). Departures are relative to the climatological mean of based on 740 surface stations in China. Sheeded areas denote positive departures.

6 Latitude-time cross-sections of the anomalous precipitation in summer of for East China ( E). The 25-yr running average is applied. Shaded areas denote positive departures. Horizontar bars a and represent the demarcation line between South China and the Yangtze River basin, and the Yangtze River basin and North China. Unit: mm

7 (a) (b) 5 ( a) WYI ( NCEP) x= t 5 ( a) DHI ( NCEP) x= t Time-series of anomalous summer monsoon indices for WYI estimated by using NCEP Reanalysis dataset (a); and DHI estimated by using NCEP Reanalysis dataset (b). WYI=U850-U200. DYI=U850-U150. Bold straight lines denote the linear regression trend. The non-smoothed curves are obtained with the 6-order polynomial fitling. Unit: m/s

8 2. Inter-decadal variation of snow over the Tibetan Plateau in preceding winter and spring and its impact on the Asian summer monsoon.

9 Ti me( year ) Anomal i es of SnowDepth Index(cm) DJF Anomalies of Snow Depth Index(cm) MA (a) (b) Ti me( year ) (c) Time-series of snow depth over the Tibetan Plateau averaged for 50 surface stations for winter (December, January and February) (a) for spring (March and April) (b) and the first EOF mode time coefficient series for spring (c). Horizontal bars represent averages for different periods. Unit: mm

10 (a) (b) Time series of the anomalous vertically integrated (from surface to 100hPa) apparent heat source (Q1) averaged for all Tibetan Plateau (75~105 E,27.5~42.5 N ) for summer (a), and spring (b). Solid lines denote 9-yr running mean curves. Unit: Wm -2

11 (a) (b) The longitude-vertical cross-sections of differences between air temperature averaged for the period of and that averaged for the period of along zonal zone of 30-45N: (a) for spring (March and April); and (b) for summer (June, July and August). Unit:. Dashed (solid) siolines denote negative (positive) temperature differences (atmospheric cooling)

12 Time series of Q1 difference between land areas (547 grid points) and oceanic areas (668 grid points) in the Asian monsoon and neighbouring oceanic regions ( E, 20 S-45 N). The sold line is the 9-yr running average. Unit: wm -2

13 (a) (b) Uf Ub (a) Time series of SSTA of averaged for tropical central and eastern Pacific (160 E-100 W, 10 S-10 N) in summer. Solid line is the linear trend. (b) Mann-Kendall test of SSTA in the central and eastern Pacific (160 E-100 W, 10 S-10 N). Bold horizontal bars are critical levels of significant level of α=0.05

14 (a) (b) Longitude-time cross-sections of SSTA decadal component (a) (unit: ) and 850 hpa zonal wind (b) (unit: ms -1 ), averaged for 10 S-10 N. Linear trend is removed. Positive anomalies are shaded.

15 (a) (b) (a) The 9-yr running mean correlation field between preceding winter (November-February) snow depths index (SDI) over the Tibetan Plateau and subsequent summer precipitation in China. Solid (dashed) lines represent positive (negative) correlation coefficents; and (b) same as (a), but for spring (March-April). Shading indicates the regions where the values pass 0.01 significance level test.

16 (a) (b) The 9-yr running mean pattern of SVD mode 2 of summer precipitation and winter (Dec.-Feb.) snow depth (a), and SVD mode 1 of summer precipitation and spring (Mar.-Apr.) snow depth (b). The percentage of the squared covariance explained is 35.77% and 40.46% by above two modes, respectively. The correlation coefficients are 0.97 and 0.96, respecitively.

17 (a) (b) Q1 Q1 Rain belt Rain belt Snowfall Rain belt Snowfall Rain belt Rain belt Rain belt Summer monsoon Q1 Summer monsoon Q1 Q1 Q1 Indian Ocean Pacific Ocean Indian Ocean Schematic diagram of possible cause of weakening of the Asian summer monsoon. Shaded areas indicate much snow or precipitation. Pacific Ocean

18 Projection of snow area (cover) for 21 century by using IPCC AR4 13 climate models under A2 and B1 Scenarios (Significant decreasing trends) 5 东亚大陆北部积雪变化 (SRESA2) 5 青藏高原积雪变化 (SRESA2) 积雪变化 (%) 0-5 cccma_cgcm3_1 csi r o_mk3_0 csi r o_mk3_5-10 gi ss_model _e_r i nmcm3_0 mi r oc3_2_medr es y = x mr i _cgcm2_3_2a ncar _ccsm3_0 ensembl e - 20 线性 ( ensembl e) 年积雪变化 (%) 0-5 cccma_cgcm3_1 csi r o_mk3_0-10 csi r o_mk3_5 gi ss_model _e_r i nmcm3_0 y = x mi r oc3_2_medr es - 15 mr i _cgcm2_3_2a ncar _ccsm3_0 ensembl e 线性 ( ensembl e) - 20 年 SRESA2 积雪变化 (%) cccma_cgcm3_1 csi r o_mk3_0 csi r o_mk3_5 东亚大陆北部积雪变化 (SRESB1) gi ss_model _e_r i nmcm3_0 6 mi r oc3_2_medr es 4 mr i _cgcm2_3_2a ncar _ccsm3_0 2 ensembl e 0 线性 ( ensembl e) y = x 年积雪变化 (%) cccma_cgcm3_1 csi r o_mk3_0 csi r o_mk3_5 青藏高原积雪变化 (SRESB1) gi ss_model _e_r 6 i nmcm3_0 mi r oc3_2_medr es 4 mr i _cgcm2_3_2a ncar _ccsm3_0 2 ensembl e 0 线性 ( ensembl e) y = x 年 SRESB1 Northern Part of East-Asia( E) A2: -6.35%(relative to ) B1:-2.41% Tibetan Plateau( E, N) A2:-8.24% B1:-4.28%

19 Based on the observed and simulated evidences of climate change in China for the 20th century, it is very likely that greenhouse gas forcing has been the dominant cause of the observed warming in China over the last 50 years. But we cannot answer whether the anthropogenic forcing has caused the changes of patterns of rainfall, floods/droughts in China, and East Asian monsoon. Natural fluctuation of climate change can also play an important role. It needs the further studies.

20 3. Projection of future Asian summer monsoon and precipitation

21 Time-latitude cross section of summer precipitation in eastern China for

22 Summer precipitation change for (%)

23 4. Common scientific issues between China and India: monsoon, glacier melting and aerosol effects

24 Projection of monsoon index in South Asia and East Asia for (Webster and Yang:solid, Wang and Fang:dashed) (Lu and Chan)

25 The Hindu Kush-Himalayan-Tibetan glaciers are the water fountains of Asia

China s glaciers are receding rapidly In the past 50 years the glaciers in northwest China have shrunk by 21%, and are receding at a rate of 10-15

26 China s glaciers are receding rapidly In the past 50 years the glaciers in northwest China have shrunk by 21%, and are receding at a rate of meters per year. By 2050 China s western glaciers are projected to decrease by 27%. Meltwater from glaciers supplies the majority of freshwater in Asia

27 Melt and retreat of most of glaciers in western China Retreating rate of glaciers for different time period (%) 右图 :1. 盖孜河 2. 叶尔羌河 3. 和田河 4. 克里雅河 5. 新青峰冰帽 6. 格拉丹东山区 7. 朋曲河 8. 岗日嘎布山 9. 阿尼玛卿山区 10. 祁连山西部 11. 阿克苏河 12. 开都河 13. 喀什河 14. 四棵树河 15. 乌鲁木齐河 ( 引自 : 刘时银等,2006)

28 Water supply for different rivers by glacier melting Yangtze-River 8.8% Yellow River 0.8% Nujiang River 5.9% Lan Canjiang River 4.0% E r Qisi River 7.7% Average: 5.44% Ganges River 9.7% Indus River 40.4%

$AOD is an index for the fraction of sunlight intercepted by particles and total aerosol concentration in the vertical column. The ABCs over South Asia peaked during the months of November-March.$

29 The integrated satellite data shows anthropogenic aerosol optical depth (AOD) in the period for four seasons. AOD is an index for the fraction of sunlight intercepted by particles and total aerosol concentration in the vertical column. The ABCs over South Asia peaked during the months of November-March. For July-August ABCs and dust reached peak values over Africa and Middle East. During the boreal spring, the ABCs and dust extended from East Asia across the North Pacific and further into Atlantic. The Amazonian Plume peaked during September to October. (Source: Ramanathan and others 2007a).

30 Observed trends in summer rainfall: (Source: Chung and Ramanathan 2006).

31 Geographical pattern of daily mean temperature changes in China in the past 50 years (Source: Xu and others 2006).

Regional and annual mean direct SW radiative forcing by ABCs over South Asia (0 N-4 N, 6 E-9 E), Southeast Asia (10 S- 2 N, 9 E-13 E), East Asia (2 N-54 N, 75 E-145 E), China, and India.

32 Regional and annual mean direct SW radiative forcing by ABCs over South Asia (0 N-4 N, 6 E-9 E), Southeast Asia (10 S- 2 N, 9 E-13 E), East Asia (2 N-54 N, 75 E-145 E), China, and India. The forcings are for the all-sky condition with the unit W m-2. The values inside the parentheses are the percentages of ABCs forcing relative to the background conditions (natural aerosols).

o f u n u s u a l e v e n t s s e v e r a l y e a r s a g o c r e a t A s e r i e s o f u n u s u a l e v e n A series of unusual events several years ago created a blanket of pollution over the

33 o f u n u s u a l e v e n t s s e v e r a l y e a r s a g o c r e a t A s e r i e s o f u n u s u a l e v e n A series of unusual events several years ago created a blanket of pollution over the Indian Ocean. In the second half of 1997, smoke from Indonesian fires remained stagnant over Southeast Asia while smog, which is tropospheric, spread more rapidly across the Indian Ocean toward India. The Figure shows the pollution over Indonesia and the Indian Ocean on October 22, White represents the aerosols (smoke) that remained in the vicinity of the fires. Green, yellow, and red pixels represent increasing amounts of tropospheric ozone (smog) being carried to the west by highaltitude winds (Source: NASA 1997). A pollutant plume as seen by satellite. 图 26 图 2 6 图 26

34 (a) (e): Aerosol Index measured by Earth Probe TOMS (Total Ozone Mapping Spectrometer) during the Asian dust storm of April 2001 (Source: NASA 2001a). Ranjeet, 2008

35 Thank you!

Changes of The Hadley Circulation Since 1950

Changes of The Hadley Circulation Since 1950 Xiao-Wei Quan, Henry F. Diaz, Martin P. Hoerling (NOAA-CIRES CDC, 325 Broadway, Boulder, CO 80305) Abstract The Hadley circulation is changing in response to