This is a grant under a Climate Variability and Predictability (CLIVAR) Program pilot project called DRICOMP, for the Drought in Coupled Models Project, which focuses on making initial explorations into the mechanisms of drought as they are represented in the output of global climate models and on attempting to assess the reliability of these models in simulating drought.
Droughts are the nation's costliest natural disasters, with average annual impacts of $6-8 billion in the United States alone. The physical and dynamical mechanisms that lead to drought and the potential impacts of climate change on drought characteristics are, however, only poorly understood. This study represents an initial attempt to answer two research questions:
. To what degree do surface-atmosphere interactions drive the stochastic characteristics of drought, including drought duration, magnitude, and recurrence, over selected regions?
. How will anthropogenic climate change affect the physical and dynamical mechanisms that lead to drought, and subsequently the stochastic characteristics of drought?
Stochastic characteristics of drought will be evaluated globally based on observed climate data and all 19 transient twentieth-century coupled climate simulations in the World Climate Research Program Coupled Model Intercomparison Project (WCRP CMIP3) data archive. A combined composite and multiple regression analysis will be used in an effort to objectively identify statistically significant patterns of antecedent and contemporaneous sea surface temperature (SST) and soil moisture (simulations only) associated with drought events. The role of surface-atmosphere forcing in the onset, persistence, and recession of drought events will then be assessed based on the amplitude and robustness of surface anomaly composites and multiple regression coefficients. Results will be compared between observations and simulations, and between models. Finally, the analysis will be repeated for all paired pre-industrial control and forced stabilization simulations in the CMIP3 data archive; potential impacts of climate change will be evaluated by comparing the drought characteristic and surface-atmosphere drought forcing between the control and forced stabilization simulations for all models.
Broader impacts will be to improve our understanding of the stochastic nature of drought and the physical mechanisms that lead to drought events; the analyses will help to improve drought planning and management.
