Component Definitions

In each case below, components are presented as standardized anomalies, and summarized on a monthly and seasonal basis. Standardized anomalies are calculated by taking the difference between the component value in the month or season at hand and its average value during the reference period, 1961-1990, and dividing that difference by the standard deviation of that component’s values during the reference period for that month or season. Calculations reflect the grids in each region, where grids are defined as 2.5 degrees latitude and longitude.

High temperatures – Frequency of daily temperatures above 90^th percentile

Low temperatures – Frequency of daily temperatures below the 10^th percentile

Heavy rain – Maximum 5-day rainfall in the month or season

Drought – Maximum number of consecutive dry days (daily precipitation less than 1mm) per year, with linear interpolation between yearly values to approximate monthly and seasonal values

High wind – Frequency of daily mean wind speeds above the 90^th percentile, as measured by wind power, which has been shown to be proportional to wind damages. Wind power is defined as: (1/2)ρw³, where w is the daily mean wind speed and ρ is the air density (taken to be constant at 1.23 kg/m³).

Sea level – Sea level measurements are on a monthly basis via tide gauges located at 76 stations with reliable time series. The tide gauges measure sea level relative to the land below, but since the land is moving in many places, this component measures the combined effect on coastal shorelines of land movements and sea level changes.

Data sources can be found here. More information on component definitions is available by downloading the Development & Design document.