Spreadsheet of areal reduction factors by region in Florida (Areal_reduction_factors.xlsx)

The Florida Flood Hub for Applied Research and Innovation and the U.S. Geological Survey have developed projected future change factors for precipitation depth-duration-frequency (DDF) curves at 242 National Oceanic and Atmospheric Administration (NOAA) Atlas 14 stations in Florida. The change factors were computed as the ratio of projected future to historical extreme-precipitation depths fitted to extreme-precipitation data from downscaled climate datasets using a constrained maximum likelihood (CML) approach as described in https://doi.org/10.3133/sir20225093. The change factors correspond to the periods 2020-59 (centered in the year 2040) and 2050-89 (centered in the year 2070) as compared to the 1966-2005 historical period.
An areal reduction factor (ARF) is computed to convert rainfall statistics of a point, such as at a weather station, to an area, such as a watershed or model grid cell. Regions considered for the development of change factors as part of this study study are taken from NOAA National Center for Environmental Information (NCEI) U.S. Climate Divisions for the state of Florida with some modifications in south Florida. A Microsoft Excel workbook is provided which tabulates areal reduction factors (ARF) by ARF region, event duration, and model grid-cell area. The ARF were developed for each ARF region based on the PRISM gridded precipitation dataset for Florida. The PRISM dataset is based on the Parameter-elevation Relationships on Independent Slopes Model (Daly and others, 2008).