Future Projections of Precipitation Characteristics in Asia

Experiment Model Model –MRI-CGCM2.2 (Yukimoto et al. 2001) –AGCM: T42 (2.8x2.8), L30 (top at 0.4hPa) –OGCM: 2.5x( ), L23 (uppermost layer 5.2m) Historical run Historical run –Forcings –GHGs: CO2, CH4, N2O, CFCs (Hansen et al. 1998) –Sulphate aerosol: direct only (Mitchell and Johns 1997) –Solar forcing: change of solar constant (Lean et al. 1995) –Volcanic activity: stratospheric aerosol (Sato et al. 1993) –Spin up + control run 350 years –Monsoon (Rajendran et al. 2004) –3 ensembles, –I.C. from control, 50 year apart Scenario run for 21st century Scenario run for 21st century –SRES A2 and B2 scenario –3 ensembles each,

Annual Mean Change

Annual mean surface air temperature change A2 B2 60W S 90N El Nino-like “mean” SST change is noticed in the tropical Pacific.

Annual mean precipitation changes A2 B2 Pattern of precipitation change is similar to each other. 90N 30S W

Global Warming pattern and ENSO pattern

ENSO composite of surface temperature and precipitation in the model > The control experiment of the MRI CGCM2 succeeds to simulate interannual variability associated with ENSO.

partial correlation We try to distinguish ENSO effect and global warming influence by partial correlations. Top panel shows annual mean surface air temperature correlation to global warming signal, and Bottom panel shows annual mean surface air temperature correlation to model El Nino. thus, quite different from each other for temperature, but for precipitation …

partial correlation warming ENSO DJFJJA In Asia, ENSO-related precip change is equally important as global warming.

Analysis of Daily Precipitation Characteristics

Present Eastward shift of precipitation over the equatorial Pacific > El Nino like mean response Annual mean precipitation F – P Future MRI-CGCM2

Total amount Intensity negative area less than that in total precipitation Frequency negative area more than that in total precipitation Changes in 3 characteristics in precipitation ANNUAL

Changes in 3 characteristics in precipitation - classification T F I % – – – – 0.1 5– – + – 2.4 7– – – – – (all increase or decrease) 〜 60% 3+7 (less freq. but intensify) 〜 34%

Consistency among 3 ensemble members (%)

Consistency among 3 ensemble members (%)

Consistency among 3 ensemble members (%)

Consistency among 3 ensemble members (%)

Consistency among 3 ensemble members (%)

Consistency among 3 ensemble members (%)

Consistency among 3 ensemble members (%)

Consistency among 3 ensemble members (%)

Consistency among 3 ensemble members (%)

Consistency among 3 ensemble members (%)

classification B A B A2 ANNUAL

classification B A B A2 ANNUAL

classification: consistency for 3 members B A B A2 ANNUAL

seasonal change in total precip, frequency and intensity [Changjiang] % significant 70% significant + – Total amount Frequency Intensity

seasonal change in total precip, frequency and intensity [Changjiang] % significant 70% significant + – Total amount Frequency Intensity

Occurrence frequency of annual mean precipitation greater than mean+2s.d.(E2) Present F/P Future ANNUAL

Frequency ratio (F/P) of precipitation greater than mean+2s.d.(E2) DJF ANN JJA Probability of heavy precipitation year generally increases in Asia except in summertime North China

Frequency distribution of JJA-mean precipitation In South China, both the mean and standard deviation increase in F, with more probability of occurrence in precip range more than 700 mm/season and less than 300 mm/season ranges in the A2 scenario experiment. In North China, a decrease of good rain year in JJA is simulated. South ChinaNorth China mm/day Green: present Red: future frequency intensity

JJA moisture flux and its divergence Present F-P Future Increased moisture content and intensified subtropical anticyclone resulted in increased precipitation in East Asia; increased moisture content is responsible for India

Summary SRES-A2 and B2 scenario ensemble runs are performed with MRI-CGCM2. El Nino-like mean changes are noted in the tropics. Both the frequency and intensity increase in about 40% of the globe, while they decrease in about 20% of the globe. East Asia is a region where summertime wet-day frequency decreases but precipitation intensity increases. This is related to increased atmospheric moisture content and an El-Nino like mean SST change and associated circulation changes. A decrease in summer precipitation in North China is also noted.