Drought Dynamcis Over Contiguous US as projected by RCP4.5 and RCP8.5 Projection Scenarios

Title: Drought Dynamics over contiguous US as projected by RCP4.5 and RCP8.5 projection scenarios

This study analyzes the different frequency components in the annual cycle of daily precipitation produced by 19 General Circulation Models (GCMs) as part of Coupled Model Intercomparison Project Phase5 (CMIP5) initiative for 20^th century simulations (1950-2005) and projection scenarios (2020-2075) to test the hypothesis that in the warming world the high frequency components of the annual cycle in the known record over contiguous US shall become either aperiodic or reduce in amplitude. The changes in the annual cycle could provide a basis to the enhanced precipitation extremes in the warming world and are studied by analyzing two warming scenarios known as Representative Concentration Pathways (RCPs) 4.5 and 8.5, where in the radiative forcing is stabilized at 4.5 and 8.5 W m^-2, respectively by the year 2100, and contrasting them with the 20^th century simulations. The data is obtained from NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) initiative; the RCP4.5 is a hypothetical scenario that embeds the cost-minimizing pathway whereas the RCP8.5 provides gravest of the warming scenarios with no mitigation efforts. The changes in the spatial distribution of the amplitude of frequency components in the annual cycle will be studied to understand the impact of mean state on the severity and the extent of precipitation extremes on the interannual timescales and their implication on drought dynamics over US in the warming world.