Newsletter No.4 October-1998




Mr.Yoshiharu Iwasa
I joined the Global Warming Research Group of the FRSGC on April 1,1998,and I am deeply thankful for having received this research opportunity.
My current work is to investigate the radiative-convective equilibrium in the Earth's atmosphere using simplified models in which radiative and convective processes can actually interact with each other.
The main research being carried out by the FRSGC is on the global climate prediction with use of the General Circulation Models (GCMs),where cumulus convection is treated only by parameterization because it is just a sub-grid scale phenomenon.
However,the cumulus convection is one of the basic processes concerned with the radiative-convective equilibrium which regulates the thermal structure within the Earth's troposphere.
In addition,it involves a lot of unsolved problems by itself,such as interactions with radiative processes,mechanisms determining water vapor distribution,and responses in warming situations.
I hope I can contribute my expertise to our project from the viewpoint of the sub-grid scale,concentrating on the role of the cumulus convection as an elementary process in the climatological system.I am looking forward to interacting with you.Thank you.






Dr.Koutarou Sakai
I have joined the Global Warming Research Program and belong to the Paleoclimate Research Group.Before I came here, I worked on variability of the thermohaline circulation on the timescales ranging from a century to millennia using a two-dimensional (one horizontal and one vertical axes)thermohaline circulation model of the oceans,which may be coupled to an atmospheric EBM (energy balance model).I am still working on the same topic but started using a full three-dimensional OGCM,namely GFDL Modular Ocean Model.
One such possible paleoclimate event that is closely related to this topic is the so-called Dansgaard-Oeschger oscillation that can be clearly observed in the paleoclimatic records for the late glacial in the last Ice Age cycle.The millennium timescale quasi-periodic climate change has been revealed through analyses of temperature proxy in the ice cores from Greenland,and the amplitude of the oscillation is more than half that of the glacial-interglacial temperature change itself. There has also been revealed similar variability in the North Atlantic paleoceanographic records that can be correlated to the Greenland records.
I will continue investigation the climate variability focusing on the role of the North Atlantic thermohaline circulation.

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