The brand new PMIPdos middle-Holocene runs can be used (Braconnot ainsi que al

2007a). We will refer to these experiments as the 6Kyr runs. Coastlines, vegetation, and ice sheets are identical to the PI simulations. CO₂ and aerosols are also identical to the PI while there is a modest reduction in methane concentration (from 760 to 650 ppbv). Orbital parameters representative of 6000 years before the present are taken from Berger and Loutre (1991). Most significantly, orbital precession causes the seasonal cycle of insolation in the Northern Hemisphere to amplify, while the duration of summer is reduced; the seasonal amplitude of ?SW_v,TOA? increases by 2.5% relative to the PI climate. Enhanced obliquity causes more high-latitude insolation in the annual mean. We note that the sum of all mid-Holocene forcing agents is symmetric about the equator in the annual average. Six different model simulations of 6Kyr are analyzed.

b. Performance

₂, LGM, and 6Kyr experiments in sections 3b(1)–3b(3). The change in annual mean P_Cent in the three forcing experiments is plotted against the change in annual mean AHT_EQ and ?SST in the top and bottom panels of Fig. 10, respectively. Leer más