Average Annual Summer Precipitation - 4km- Historical and RCM projections

Comparison between simulated projections of change in summer precipitation produced by RegCM3 with boundary conditions from 3 GCMs (GFDL, GENMOM and ECHAM5).
Results show vastly different results in trends of change.
GFDL did not provide climate projections for the intermediate period 2015-2030 but the otwo other GCMs provided boundary conditions for RegCM3. We see that summer drought pattern are more pronounced during this period than during the later period (2045-2060). This is an important finding relevant to simulations using envelope models. If results of climate change concentrate on the later period, conditions are more moderate than earlier in the century.
A second finding is that the 3 models show vastly different patterns of change: GENMOM causes drought summer conditions in the SW part or the western states region and wetter conditions in the NW by 2015, conditions much relieved by 2045; ECHAM5 causes a deep drought in the 2 southern thirds of the region that is only partially mitigated by 2045; GFL show some dorught level at the northern edge of the region by 2045.