Terrestrial Precipitation Analysis (TPA): A resource for characterizing long-term precipitation regimes and extremes

1. World-wide, climate change is altering precipitation amounts, variability and extremes (e.g. droughts), and these changes are altering ecosystem structure and function. Precipitation manipulation experiments in terrestrial ecosystems around the world have identified many consequences of altered precipitation regimes, but a lack of standardized protocols has complicated attempts to synthesize results from these studies. Thus, there is a clear need to identify standard, ecologically relevant treatments that can be more easily compared across systems. Tools that facilitate comparisons of precipitation statistics across sites would allow researchers to (1) optimize treatments for multi-site precipitation studies and (2) place past and current experiments in the context of historical precipitation patterns. 2. To address these needs, we created the Terrestrial Precipitation Analysis package. This package is comprised of the Precipitation Trends (P-Trend), Precipitation Attributes (P-Att) and Precipitation Manipulation (P-Man) tools. Combined, these web tools allow researchers to easily calculate fundamental precipitation statistics for past, present and projected future precipitation regimes for any terrestrial location in the world. 3. The P-Trend tool allows researchers to visualize and download long-term precipitation, potential evapotranspiration, and drought index records derived from a global gridded data set for any study location. The P-Att tool allows researchers to characterize the general precipitation regime (including extreme events) at any study site and obtain estimates of precipitation under a severe climate change scenario. The P-Man tool calculates the proportional change in precipitation required to achieve any level of precipitation extremity based on either long-term interpolated data or user-provided long-term, site-based precipitation records.