We report on drought frequency, duration, severity, and intensity at three different time scales, short-term (3 months), medium-term (6 months) and long-term (12 months). These different time scales are approximately equivalent to meteorological, agricultural, and hydrological drought, respectively. We do this for 30 sites across Aotearoa New Zealand monitored by NIWA (National Institute for Water and Atmospheric Research) from 1972 to 2022. To measure drought events, this dataset uses the Standardised Precipitation-Evapotranspiration Index (SPEI), which incorporates temperature and precipitation.
Drought frequency is the number of drought events across a specified period of time. Drought duration is the number of months in a drought event. Severity is a measure of how dry a drought event is, and intensity is a measure of drought severity scaled by its duration. Extreme dryness is indicated by SPEI values of less than -2.
Variables:
id: Relates to drought_event, whether a drought event or non-drought event
year: Year
month: Month
site: 30 NIWA Climate stations
time_scale & drought_type: The drought the SPEI values represent given at 3, 6, and 12 months
spei: SPEI is the balance of PET and P
spei_class: Categorising SPEI values into what they may represent climate-wise
imputed_value: Whether the value was imputed using linear interpolation
drought_event: whether the sequence of SPEI values meet the threshold for a drought event
duration: Duration of the drought event in months
start_event: The start date of a drought event
severity: Sum of the SPEI values per drough event that are below -1
intensity: Sum of the SPEI values per drought event standardised against time (severity/duration)
lat: Latitude
lon: Longitude
