- Related Research Areas
- Climate Variability & Change
We propose to evaluate natural and forced variations in western US climate simulated by the NASA Goddard Earth Observing System (GEOS) Model. Realistic predictions of natural and forced variability on seasonal, interannual, and ultimately decadal timescales are required for accurate projection and attribution of anthropogenically-forced climate change over the next century. This information would be particularly useful to policy makers in California and other western states faced with the prospect of rapid near-term changes in regional climate and the challenge of new regulatory frameworks for climate-change adaptation. We seek to quantify the predictability of natural and forced fluctuations in the western US by evaluating the fidelity of the GEOS analysis for the recent historical climate record using out-of-sample Earth observations collected by NASA. Our partner in the project is the California Energy Commission (CEC). CEC organizes research, development, and demonstration programs to mitigate and adapt to climate change impacts. CEC conducts these activities to support decision makers in California agencies responsible for policy formation and implementation to address climate change. Our project would advance CEC’s long-range objective to develop detailed regional climate forecasts for state policy makers. Results from this investigation will be contributed to the CEC’s biannual assessments of the climate in the western U.S. These assessments will provide the scientific foundation for development of adaptation plans starting in spring 2009. In order to quantify the skill of models developed for decadal forecasts, the CEC has commissioned evaluations of the hindcasts for regional climate from the same models. In support of this activity, we will assess the fidelity of the Modern Era Retrospective-analysis for Research and Applications (MERRA) from GEOS 5. This is a challenging problem since recent increases in western temperature and precipitation have been linked both to natural low-frequency oscillations and to anthropogenic influences. First, we will evaluate the MERRA analyses using out-of-sample NASA observations. We will examine effects of natural variability on western US climate in GEOS 5 adjusted by assimilation of atmospheric temperatures, moisture, and winds. Coastal climate anomalies have been linked to variations in ENSO and PDO, although the magnitudes and spatial distributions of the anomalies do not match natural variability and could be related to anthropogenic factors. Second, we will evaluate hindcasts using GEOS 5 initialized from the MERRA reanalysis. We will characterize the hindcasts relative to MERRA and observations at hindcast verification times. We will quantify improvements in the fidelity of another set of hindcasts forced with observed changes in greenhouse gases and aerosols. We will characterize the sensitivity to initial conditions for western US simulations using hindcasts run in climate mode.
Project PI: William Collins/University of California, Berkeley
University Of California,395 McConne Berkeley, CA
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