future projections of precipitation characteristics in asia

Future Projections of Precipitation Characteristics in Asia

Experiment•ModelModel–MRI-CGCM2.2MRI-CGCM2.2 (Yukimoto et al. 2001) (Yukimoto et al. 2001)

–AGCM: T42 (2.8x2.8), L30 (top at 0.4hPa)AGCM: T42 (2.8x2.8), L30 (top at 0.4hPa)–OGCM: 2.5x(0.5-2.0), L23 (uppermost layer 5.2m)OGCM: 2.5x(0.5-2.0), L23 (uppermost layer 5.2m)

•Historical runHistorical run–ForcingsForcings

–GHGs: CO2, CH4, N2O, CFCs (Hansen et al. 1998)GHGs: CO2, CH4, N2O, CFCs (Hansen et al. 1998)–Sulphate aerosol: direct only (Mitchell and Johns 1997)Sulphate aerosol: direct only (Mitchell and Johns 1997)–Solar forcing: change of solar constant (Lean et al. 1995)Solar forcing: change of solar constant (Lean et al. 1995)–Volcanic activity: stratospheric aerosol (Sato et al. 1993)Volcanic activity: stratospheric aerosol (Sato et al. 1993)

–Spin up + control run 350 years Spin up + control run 350 years –Monsoon (Rajendran et al. 2004)Monsoon (Rajendran et al. 2004)

–3 ensembles, 1850-20003 ensembles, 1850-2000–I.C. from control, 50 year apartI.C. from control, 50 year apart

•Scenario run for 21st centuryScenario run for 21st century–SRES A2 and B2 scenarioSRES A2 and B2 scenario–3 ensembles each, 1990-21003 ensembles each, 1990-2100

Annual Mean Change

Annual mean surface air temperature change2041-2060 2081-2100

A2 A2

B2 B2

60W180030S

90N

El Nino-like “mean” SST change is noticed in the tropical Pacific.

Annual mean precipitation changes2041-2060 2081-2100

A2 A2

B2 B2

Pattern of precipitation change is similar to each other.

90N

30S0 180 60W

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

DJF JJA

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 2041-2060

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 %1 + + + 40.52 + + – 2.73 + – + 20.94 + – – 0.15 – + + 0.06 – + – 2.47 – – + 13.88 – – – 19.5

1+8 (all increase or decrease) 〜 60% 3+7 (less freq. but intensify) 〜34%

Consistency among 3 ensemble members

4.4 0.2 0.3 1.3 (%)

Consistency among 3 ensemble members

6.7 0.7 0.5 2.4 (%)

Consistency among 3 ensemble members

9.0 1.1 0.8 3.9 (%)

Consistency among 3 ensemble members

11.9 2.8 0.8 3.6 (%)

Consistency among 3 ensemble members

17.5 3.0 1.2 4.8 (%)

Consistency among 3 ensemble members

21.3 4.0 1.6 5.4 (%)

Consistency among 3 ensemble members

21.8 5.9 2.4 7.6 (%)

Consistency among 3 ensemble members

22.7 6.3 3.1 7.7 (%)

Consistency among 3 ensemble members

25.1 8.1 3.4 6.0 (%)

Consistency among 3 ensemble members

26.5 8.8 3.8 6.3 (%)

classification

2041-2060 B2

2041-2060 A2

2081-2100 B2

2081-2100 A2ANNUAL

classification

2041-2060 B2

2041-2060 A2

2081-2100 B2

2081-2100 A2ANNUAL

classification: consistency for 3 members

2041-2060 B2

2041-2060 A2

2081-2100 B2

2081-2100 A2ANNUAL

seasonal change in total precip, frequency and intensity[Changjiang] 2041-2060

90% significant 70% significant

+ –

Total amount

Frequency

Intensity

seasonal change in total precip, frequency and intensity[Changjiang] 2081-2100

90% 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 China North China

mm/day

Green: present Red: future

freq

uenc

y

freq

uenc

yintensity 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

SummarySRES-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.