To calculate Precipitation Risk, we use the variables [Copernicus Climate Data Store (CDS)]:
By combining these three variables, we can analyze different and complementary aspects of precipitation hazard. The first indicator measures average precipitation on a rain day, outlining the general character of the area's rainfall regime. The second indicator is related to the possibility of prolonged soil saturation. The last indicator is related to the rarest and most violent precipitation events. To define risk levels, we consider the return period RP (see Cold Wave Risk) for these indicators.
This methodology for 'Precipitation Risk' assessment is a very detailed and scientifically robust climatological analysis. It is not limited to a single indicator, but combines three that describe different and complementary aspects of the rainfall regime, and then classifies their rarity through return period. This approach is fully supported by scientific literature.
The three indices used — SDII, VWD (R95pTOT), and EWD (R99pTOT) — are all standardized indices recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI).
Modern climate science recognizes that climate change does not only alter one aspect of precipitation (e.g., annual total), but modifies its entire 'character'. The combined use of SDII, R95pTOT and R99pTOT serves to capture precisely this complexity.
Since we combine three different indices, a common metric is needed to compare and aggregate them. Return period (RP) is the perfect statistical tool for this purpose. It transforms physical values of three different indices (mm/day for SDII, mm for R95pTOT and R99pTOT) into a single probability and risk scale. The sources for this approach are the same cited previously.
In conclusion, our methodology represents a comprehensive precipitation risk analysis. It is scientifically founded on the use of international standard indices (ETCCDI), aligned with the most recent scientific conclusions (IPCC AR6), and applies a robust and standardized statistical method (Return Period) for risk classification
This methodology for 'Precipitation Risk' assessment is a very detailed and scientifically robust climatological analysis. It is not limited to a single indicator, but combines three that describe different and complementary aspects of the rainfall regime, and then classifies their rarity through return period. This approach is fully supported by scientific literature.
The three indices used — SDII, VWD (R95pTOT), and EWD (R99pTOT) — are all standardized indices recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI).
• [Indices for monitoring changes in extremes based on daily temperature and precipitation data](Indices for monitoring changes in extremes based on daily temperature and precipitation data)
This document consolidates precise definitions of the considered indices. The scientific community has adopted them because they effectively capture the characteristics of rain events leading to different impacts.
Modern climate science recognizes that climate change does not only alter one aspect of precipitation (e.g., annual total), but modifies its entire 'character'. The combined use of SDII, R95pTOT and R99pTOT serves to capture precisely this complexity.
• [Climate Change 2021: The Physical Science Basis](Climate Change 2021: The Physical Science Basis)
Chapter 11 ('Weather and Climate Extreme Events in a Changing Climate') of this report analyzes observed and projected changes for individual extreme precipitation indices (such as R95pTOT and R99pTOT), and discusses how the character of precipitation is generally changing. The scientific conclusion is that globally there is a trend toward generally more intense daily rainfall (increasing SDII) and an increasing contribution of extreme events to annual total (increasing R95p/R99p). Our methodology is therefore aligned with the conclusions of the latest IPCC report.
Since we combine three different indices, a common metric is needed to compare and aggregate them. Return period (RP) is the perfect statistical tool for this purpose. It transforms physical values of three different indices (mm/day for SDII, mm for R95pTOT and R99pTOT) into a single probability and risk scale. The sources for this approach are the same cited previously.
In conclusion, our methodology represents a comprehensive precipitation risk analysis. It is scientifically founded on the use of international standard indices (ETCCDI), aligned with the most recent scientific conclusions (IPCC AR6), and applies a robust and standardized statistical method (Return Period) for risk classification