High-resolution climate simulation of the last glacial maximum |
| |
Authors: | Seong-Joong Kim Thomas J Crowley David J Erickson Bala Govindasamy Phillip B Duffy Bang Yong Lee |
| |
Institution: | (1) Korea Polar Research Institute, KORDI, PO Box 32, Incheon, 406-840, South Korea;(2) School of Geosciences, Grant Institute, The University of Edinburgh, Edinburgh, EH9 3JW, UK;(3) Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA;(4) Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94550, USA |
| |
Abstract: | The climate of the last glacial maximum (LGM) is simulated with a high-resolution atmospheric general circulation model, the
NCAR CCM3 at spectral truncation of T170, corresponding to a grid cell size of roughly 75 km. The purpose of the study is
to assess whether there are significant benefits from the higher resolution simulation compared to the lower resolution simulation
associated with the role of topography. The LGM simulations were forced with modified CLIMAP sea ice distribution and sea
surface temperatures (SST) reduced by 1°C, ice sheet topography, reduced CO2, and 21,000 BP orbital parameters. The high-resolution model captures modern climate reasonably well, in particular the distribution
of heavy precipitation in the tropical Pacific. For the ice age case, surface temperature simulated by the high-resolution
model agrees better with those of proxy estimates than does the low-resolution model. Despite the fact that tropical SSTs
were only 2.1°C less than the control run, there are many lowland tropical land areas 4–6°C colder than present. Comparison
of T170 model results with the best constrained proxy temperature estimates (noble gas concentrations in groundwater) now
yield no significant differences between model and observations. There are also significant upland temperature changes in
the best resolved tropical mountain belt (the Andes). We provisionally attribute this result in part as resulting from decreased
lateral mixing between ocean and land in a model with more model grid cells. A longstanding model-data discrepancy therefore
appears to be resolved without invoking any unusual model physics. The response of the Asian summer monsoon can also be more
clearly linked to local geography in the high-resolution model than in the low-resolution model; this distinction should enable
more confident validation of climate proxy data with the high-resolution model. Elsewhere, an inferred salinity increase in
the subtropical North Atlantic may have significant implications for ocean circulation changes during the LGM. A large part
of the Amazon and Congo Basins are simulated to be substantially drier in the ice age—consistent with many (but not all) paleo
data. These results suggest that there are considerable benefits derived from high-resolution model regarding regional climate
responses, and that observationalists can now compare their results with models that resolve geography at a resolution comparable
to that which the proxy data represent. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|