High-Resolution Future Climate Projections over Contiguous United States

We will present an overview of projected changes in climatology and extremes using high- resolution dynamically downscaled ensembles. We use weather research and forecast (WRF) model to conduct six decadal simulations with different boundary conditions and model setup. The spatial resolution is 12-km. The model covers most of North America (domain size: 7200 km × 6180 km). The boundary conditions employed are the Geophysical Fluid Dynamics Laboratory Earth System Model with Generalized Ocean Layer Dynamics component (GFDL-ESG2G), Community Climate System Model, version 4 (CCSM4), and the Hadley Centre Global Environment Model, version 2-Earth System (HadGEM2-ES). We analyze climate changes over the entire model domain and seven subregions, divided based on national climate assessment. We will present the climate change in late 21st century relative to the reference period of 1995–2004. We will consider the impacts of spectral nudging and different boundary conditions on future climate projections for temperature- and precipitation-based indices. For precipitation, we will investigate the changes of rainstorm size, frequency, intensity and duration. In addition, in our previous study (Chang et al. 2016), we found that projected changes are smaller than model-observation biases. We therefore developed a “data-driven simulations” that applies model-projected changes to observational data. This method will be applied to all the future projections presented in this study to show the uncertainties of future climate projections due to different boundary conditions and model setup.

Reference:

Chang, W., M. Stein, J. Wang, V. R. Kotamarthi, and E. Moyer, 2016: Changes in Spatio-temporal Precipitation Patterns in Changing Climate Conditions. Journal of Climate. DOI: http://dx.doi.org/10.1175/JCLI-D-15-0844.1.