Make SPEIbase data PRIO-GRID compatible

The function takes monthly SPEIbase data and transforms it to the temporal resolution defined by PRIO-GRID date intervals (which may be quarterly, yearly, or other intervals), while also performing spatial aggregation to the PRIO-GRID resolution.

Usage

speibaseN(interval, time_agg_fun)

Arguments

interval

Integer. The month interval to calculate SPEI over. E.g., if the interval is 6, then monthly precipitation and potential evapotranspiration are aggregated over the last 6 months, then the SPEI (anomaly) is calculated. This is done for each month.

time_agg_fun

Character. Either "mean" or "max". Original data is monthly, so if PRIO-GRID is lower resolution, then we need to aggregate over time. Currently, mean and max functions are implemented.

Value

A SpatRaster object (from the terra package) with spatio-temporal resolution as defined in PRIO-GRID.

References

Beguería S, Latorre B, Reig F, Vicente-Serrano SM (2024). “SPEIbase v.2.11.” Beguería S, Vicente-Serrano SM, Reig F, Latorre B (2014). “Standardized Precipitation Evapotranspiration Index (SPEI) Revisited: Parameter Fitting, Evapotranspiration Models, Tools, Datasets and Drought Monitoring.” International Journal of Climatology, 34(10), 3001–3023. ISSN 1097-0088, doi:10.1002/joc.3887 , 2018-08-29.

See also

read_speibase for reading and calculating SPEIbase, read_cru_pet for input-data to SPEIbase, read_cru_pre for input-data to SPEIbase, pg_date_intervals for PRIO-GRID temporal boundaries, robust_transformation for spatial aggregation, get_pgfile for file management

Examples

if (FALSE) { # \dontrun{
# SPEI-6 averaged over PRIO-GRID time-interval using the mean.
spei6_mean <- speibaseN(interval = 6, time_agg_fun = "mean")
} # }