Hydroclimatic variability in southwestern North America

University Of New Mexico, Albuquerque NM

Investigators

Abstract

This is one of 16 Rapid Response (RAPID) projects funded as the result of a Dear Colleague Letter (NSF 11-006) encouraging diagnostic analyses of climate model simulations prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5). Research conducted in these projects is expected to lead to more detailed model intercomparisons, better understanding of robust model behaviors, and better understanding and quantification of uncertainty in future climate simulations. Analysis conducted in this project examines the veracity and robustness of the climate change simulations for the AR5 as part of the Coupled Model Intercomparison Project version 5 (CMIP5), particularly with respect to projected hydroclimatic changes in the water limited region of southwestern North America. Warming trends are already particularly pronounced in this region in the spring season, which is a critical issue for surface hydrology due to the sensitivity of snowpack to spring warming, and the relative lack of precipitation during this season. Therefore climate change at this time of year has a potentially dramatic effects on snow-fed rivers and on soil moisture during the start of the growing season. The projected hydrologic changes associated with these trends are one of the most pronounced and significant signals that appeared in an earlier generation of climate model simulations prepared for the IPCC Fourth Assessment Report (AR4), so it is important to examine CMIP5 simulations carefully to examine the hydroclimatic processes simulated in current model. The research also examines the simulation of summer rainfall in the region, and in this season simulations used for AR4 were not consistent from one model to another. Thus, the extent to which the new generation of models produces a consistent response of summertime rainfall in the southwest to greenhouse gas increases is considered. Model outputs to be examined include maximum and minimum temperature, focusing on the spring and summer seasons, surface fluxes in the spring and summer seasons, soil moisture, snowfall in mountainous regions in the winter and spring seasons, and pecipitation from winter through summer. The broader impact of the project lies in its support of the IPCC AR5, which is intended to provide information on climate change and its consequences to decision makers worldwide. The hydroclimate of southwestern North America is of great societal interest given the large population and population growth in the region, as well as the importance of the region for agriculture and the sensitive ecosystems contained within it.