Simulation of the climate of 18,000 years BP: Results for the North American/North Atlantic/European sector and comparison with the geologic record of North America

The LGM surface climate and atmospheric circulation over East Asia and the North Pacific in the PMIP2 coupled model simulations

“…1). This characteristic is also seen in many AGCM experiments both with prescribed SST 447 (Kutzbach and Wright, 1985;Rind, 1987;Hall et al, 1996;Dong and Valdes, 1998;Vettoretti et al, 2000) and computed SST using a mixed-layer model (Dong and Valdes, 1998;Vettoretti et al, 2000). Therefore, this seems to be a relatively robust characteristic of LGM simulations using both AGCM and CGCM.…”

“…It is interesting to note that most of these AGCM experiments show that the atmospheric circulation anomaly over the North Pacific during the LGM is cyclonic during both the boreal summer and winter (Kutzbach and Wright, 1985;Rind, 1987;Hall et al, 1996;Dong and Valdes, 1998;Vettoretti et al, 2000); a cyclonic anomaly over the North Pacific implies a weakening in the high sea level pressure (SLP) during the summer, while it implies the intensification of the low SLP during the winter.…”

The California current system during the last 136,000 years: response of the North Pacific High to precessional forcing

“…Herbert et al (2001) showed that an early warming at the California Borderland began ~24 ka, and the SST reached a maximum value at ~16 ka (late MIS 2), reflecting weakening of the California Current. This decline was attributed to a depressed summer North Pacific High influenced by the semipermanent development of a high-pressure cell over the expanded Laurentide ice sheet over continental North America (Kutzbach and Wright, 1985;Lyle et al, 1992). However, paleo-SST change at Site 1014 did not fully agree with the estimated volume change of the Laurentide ice sheet (Boulton et al, 1985).…”

“…Previous studies finding decreased productivity (Lyle et al, 1992) and an increased meridional paleo-SST gradient (Doose et al, 1997;Mangelsdorf et al, 2000;Herbert et al, 2001) have suggested that the California Current declined during the last glacial maximum. This decline has been attributed to the depressed summer North Pacific High influenced by the semipermanent development of a high-pressure cell over the expanded Laurentide ice sheet on the North American continent (Kutzbach and Wright, 1985;Lyle et al, 1992). Recently, Yamamoto et al (2004) noted that SST variation at the California margin did not fully agree with the development of the Laurentide ice sheet but did correspond to SSTs at the Japan margin, suggesting basin-scale variation in North Pacific SSTs.…”

Green Mountains and White Plains: The Effect of Northern Hemisphere Ice Sheets on the Global Energy Budget

“…Of the largescale causes of this change, much has been written about the effect of greenhouse gases (e.g., Hansen et al 1984) and varying orbital forcing (e.g., Phillipps and Held 1994); less, however, has been written considering the effect that the large ice sheets may play, especially when the ice sheets are relatively small. While the local effects of the ice sheet on the midlatitude circulation have long been considered (e.g., Cook and Held 1988;Kutzbach and Wright 1985), their global impact has been somewhat ignored and never examined with a fully coupled oceanatmosphere climate model (Manabe and Broccoli 1985). There has been much written recently about the effect that changing the contrast between the temperature and energy balance in the Northern and Southern Hemispheres can have on the position of tropical rain belts and transports of energy across the equator (e.g., Yoshimori and Broccoli 2008;Kang et al 2008;Chiang and Friedman 2012;Donohoe et al 2013).…”