TOWARD SIMULATING MID-HOLOCENE TIME SLICES WITH THE REGCM4 REGIONAL CLIMATE MODEL

We have completed a series of time-slice simulations of global climate from 21 ka to 0 ka (pre-industrial) at 3000-yr intervals with a new coupled atmosphere-ocean model, GENMOM, at a nominal model resolution of 3.75° × 3.75° in latitude and longitude. Time‑appropriate boundary conditions are specified for each 700-yr time slice which include insolation, atmospheric green house gases, continental ice sheets, and sea level. The simulations provide insights into features of the full glacial and deglacial climate such as the evolution of the global monsoons. To investigate regional Holocene climates, surface‑atmosphere feedbacks and mechanisms such as the Southwest monsoon in more detail, we are running a parallel set of simulations over North America (NA) and smaller regions within NA with our paleo-version of the RegCM4 climate model. Currently we are exploring experimental designs that optimize application of the regional model such as the model domain and resolution, multiple nesting and physics parameterizations. Preliminary results for the Holocene indicate the regional model simulations are consistent with the GENMOM forcing and have the potential to provide “added value” for data-model comparisons. We will present key aspects of our modeling effort.