Future Projections of Precipitation Characteristics in Asia.
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Transcript of 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.