1. Orbital Control of Monsoon Circulation in an accelerated
transient simulation over the last 130,000 years
Oliver Timm1, Axel Timmermann1, Ayako Abe-Ouchi2,3,
Tomonori Segawa3 and Fuyuki Saito3
(1) International Pacific Research Center,
School of Ocean and Earth Science and Technology,
University of Hawaii at Manoa, Hawaii
(2) Center for Climate System Research,
The University of Tokyo,
Kashiwa, Japan
(3) Frontier Research Center for Global Change
Japan Agency for Marine-Earth Science and Technology,
Yokohama, Japan
19. April, 2007
CL11-1TH4O- 003

2. Questions of interest Indian Monsoon Proxies Speleothems
Marine sediments
Why is there a strong obliquity signal in marine proxies, but a dominant precessional cycle in terrestrial records (Clemens and Prell, 2003;Wang et al., 2001; Cruz et al., 2005, Kelly et al, 2006) ?
Mid-month Insolation
30N Jun
What is the lead-lag relation between orbital forcing and monsoon response?
What processes in the climate system can lead to a lagged response ?
10S Dec

3. An Earth system Model of Intermediate Complexity (EMIC)
ECBilt/CLIO:
An Earth system Model of Intermediate Complexity (EMIC)
ice-sheet (topography, albedo)
greenhouse gases (CO2, CH4, N2O)
orbital forcing
External forcing
atmosphere
3 layer quasi-geostrophic
potential vorticity + ageostrophic forcing
sea ice model
(thermodynamic-dynamic)
land surface
processes
ocean
20 level-primitive equation model

4. Ice sheet forcing

5. CO2 forcing 280 ppmv Negative radiative forcing preindustrial
control level
Negative radiative forcing
[ppmv]

6. Orbital forcing more NH sum insolation less more NH sum insolation

7. JJA* Temperature Regression Pattern
Normalized Precession Index
Normalized Obliquity Index oK oK
* fixed calendar season

8. JJA* Precipitation Regression Pattern
Normalized Precession Index
Normalized Obliquity Index
cm/a
cm/a
* fixed calendar season

9. Comparison proxy - model simulation
Hulu Cave
Dongge Cave

10. Comparison proxy - model simulation
Botuvera Cave

11. JJA* Temperature and Precipitation
Anomalies:
temperature (shaded in oK)
precipitation (black contours in cm/a)
insolation (white contours -10/+10 W/m2)
Latitude
Time [ka BP]
JJA precipitation 180o phase shifted
* fixed calendar season

12. Seasonal Phase Relation 25oN
Anomalies:
temperature (shaded in oK)
precipitation (black contours in cm/a)
insolation (white contours -10/+10 W/m2)
Month in year
Time [ka BP]
Temperature and precipitation are in phase with forcing.

13. Seasonal Phase Relation 10oS
Anomalies:
temperature (shaded in oK)
precipitation (black contours in cm/a)
insolation (white contours -10/+10 W/m2)
Month in year
Time [ka BP]
Precipitation is 180o out of phase with temperature and forcing

14. Annual cycles in the South Equatorial Indian Ocean
COADS
area 15-5S / 40-70E
Annual cycle in insolation at 10oS
Precession
minimum
Precession
maximum
W/m2 oK
Month in year
Today precession maximum
(Perihel during NH winter)

15. South equatorial Indian Ocean: to temperature and orbital forcing
Seasonal precessional forcing
larger than obliquity forcing:
Model and terrestrial proxies
show precessional cycles
Precession forcing
→ anti-phase relation
between NH summer
and SH summer
monsoon
South equatorial Indian Ocean:
JJA precipitation
180o phase shift
to temperature and orbital forcing
Simulation supports
Kutzbach's (1981) hypothesis
of a direct (in phase) response
to orbital forcing

16. The THC as a agent for 41,000 obliquity cycles in the Monsoon?

17. Proxy data are provided by the following research groups
through their contribution to:
NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.
Wang, Y.J., et al., 2004.
Hulu Cave Stalagmite Oxygen Isotope Data,
IGBP PAGES/World Data Center for Paleoclimatology
Data Contribution Series #
Yuan, D., et al., 2004.
Dongge Cave Stalagmite Oxygen Isotope Data,
Data Contribution Series #
Kelly, M.J., et al., 2006.
Dongge Cave Stalagmite High-Resolution MIS 5/6 Oxygen Isotope Data,
Data Contribution Series #
Cruz, F.W., Jr., et al
Botuvera Cave, Brazil Stalagmite Stable Isotope Data.
Data Contribution Series #
Monnin, E., et al
EPICA Dome C Ice Core High Resolution Holocene and Transition CO2 Data.
IGBP PAGES/World Data Center for Paleoclimatology
Data Contribution Series #
Petit, J.R., et al., 2001,
Vostok Ice Core Data for 420,000 Years, IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series #

18. This research project was sponsored by the
Japan Agency for Marine-Earth Science and Technology
through its sponsorship
of the International Pacific Research Center.
17. April, 2007
CL11-1TH4O- 003