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

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

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

Ice sheet forcing

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

Orbital forcing more NH sum insolation less more NH sum insolation

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

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

Comparison proxy - model simulation Hulu Cave Dongge Cave

Comparison proxy - model simulation Botuvera Cave

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

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.

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

Annual cycles in the South Equatorial Indian Ocean COADS 1950-2000 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)

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

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

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 #2004-023. Yuan, D., et al., 2004. Dongge Cave Stalagmite Oxygen Isotope Data, Data Contribution Series #2004-024. Kelly, M.J., et al., 2006. Dongge Cave Stalagmite High-Resolution MIS 5/6 Oxygen Isotope Data, Data Contribution Series #2005-062. Cruz, F.W., Jr., et al. 2005. Botuvera Cave, Brazil Stalagmite Stable Isotope Data. Data Contribution Series # 2005-027. Monnin, E., et al.. 2004. EPICA Dome C Ice Core High Resolution Holocene and Transition CO2 Data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2004-055. Petit, J.R., et al., 2001, Vostok Ice Core Data for 420,000 Years, IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series #2001-076

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