Analysis of Future Drought Scenarios in Different Climatic Regions Across the United States

Abstract:

The changes in extreme weather events have been observed during the last several decades and the number of warm days in a year has increased on the global scale. The projected change in the precipitation pattern in response to warming is not uniform. In general, the difference in precipitation between wet and dry regions and between wet and dry seasons is expected to increase. Because of the changes in precipitation pattern, the characteristics of future drought scenarios might be different from that observed in the past. In this study, the characteristics of drought are investigated in terms of severity, frequency, and duration for nine representative climate regions across the United States at different time scales. The Standardized Precipitation Index (SPI) is used as the means to forecast and compare drought characteristics for different regions at different time scales, a perspective which is not obtained using other available drought monitoring indices. The North American Regional Climate Change Assessment Program (NARCCAP) provides historic as well as future precipitation from multiple regional climate models (RCMs) coupled with various global circulation models (GCMs). To evaluate the performance of the RCMs, we used the National Centers for Environmental Prediction (NCEP) North American Regional Reanalysis (NARR) precipitation data set. We analyzed the coefficient of efficiency (E) of the models for different time scale at different locations. Results from the climate model historic run were adjusted to represent the reanalysis data and the same adjustment factor was used to correct the future projections. Adjusted values of SPI obtained from the historic runs were compared with those from the future runs. The performance of climate models in characterizing drought is different in different locations. The change in drought characteristics is shown to occur in all climatic regions; however, nature of change is different.