Dr. Takasumi Kurahashi-Nakamura

Reconstruction of LGM ocean circulation from data with the adjoint method

[Background]
Understanding the behavior of the Earth's climate system under different conditions in the past is the basis for robust predictions of future climate. It is believed that the ocean circulation plays a very important role in the climate system, because it can greatly affect climate by dynamic-thermodynamical (as a medium of heat transport) and biogeochemical processes (by modifying the marine carbon cycle). In this context, studying the period of the Last Glacial Maximum (LGM) is particularly important, because it represents a climate state that is very different from today. However, the ocean circulation during the LGM is still uncertain.

The consistent and general motive of my research is interest in climate stability (or, variability) and habitability of terrestrial planets, and in studying the mechanisms for climate changes in the past on such planets using numerical climate models. In particular, I have been interested in the mechanism to determine the amount of CO2 in the atmosphere because CO2 is a very important greenhouse gas to control the surface environment of the Earth and Mars. Specific research interests of mine include:
* Mechanisms to control atmospheric CO2 level in the glacial-interglacial period.
* The role of marine carbon cycles in climate changes in the past and future.
* General understanding the behaviour of the climate system (e.g., intrinsic feedbacks)
* Regulating mechanisms of the long-timescale evolution of climate of Mars.

Kurahashi-Nakamura, Takasumi, A. Abe-Ouchi, and Y. Yamanaka, “Effects of physical changes
in the ocean on atmospheric pCO2 during the last glacial maximum, Clim. Dyn.,
DOI10.1007/s00382-009-0609-5, 2009.

Kurahashi-Nakamura, Takasumi, A. Abe-Ouchi, Y. Yamanaka and K. Misumi, “Compound
effects of Antarctic sea ice on atmospheric pCO2 change during glacial–interglacial cycle, Geophys.
Res. Lett., 34, L20708, doi:10.1029/2007GL030898, 2007.

Kurahashi-Nakamura, Takasumi, and E. Tajika, “Atmospheric collapse and transport of carbon
dioxide into the subsurface on early Mars”, Geophys. Res. Lett., 33, L18205,
doi:10.1029/2006GL027170, 2006.

Kurahashi-Nakamura, Takasumi, and E. Tajika, “Evolution of the Martian climate: effects of the
ice sheets”, Seppyo, Journal of the Japanese Society of Snow and Ice, Vol. 67, No. 2, pp.133-145,
2005 (in Japanese).

Nakamura, Takasumi, and E. Tajika, “Climate change of Mars-like planets due to obliquity
variations: implications for Mars”, Geophys. Res. Lett., 30, No. 13, 1685,
doi:10.1029/2002GL016725, 2003.

Nakamura, Takasumi, and E. Tajika, “Stability of the Martian climate system under the seasonal
change condition of solar radiation”, Journal of Geophysical Research, vol.107, no.E11, 5094,
doi:10.1029/2001JE001561, 2002.

Nakamura, Takasumi, and E. Tajika, “The Martian Climate System : Its Stability and Evolution”,
Planetary People, Journal of the Japanese Society for Planetary Science, vol.10, no.4, pp.192-201,
2001 (in Japanese).

Nakamura, Takasumi, and E. Tajika, “Stability and evolution of the climate system of Mars”,
Earth, Planets, and Space, vol.53, pp.851-859, 2001.