hydro: Derive annual hydrologic variables

In matthewkling/climatica:

Description

This is the main external function in the package, which uses the Hargreaves equation to generate a set of 5 annual water balance variables from a 48 monthly temperature and precipitation variables. The function calculates cumulative annual totals for precipitation (PPT), potential evapotranspiration (PET), actual evapotranspiration (AET), climatic water deficit (CWD), and reacharge and runoff (RAR), all in mm. Note that it does not work inside the arctic and antarctic circles.

Usage

hydro(rasters, temp_scalar = 1, ppt_scalar = 1, ncores = 1,
  already_latlong = F, filename, m)

Arguments

rasters	stack of 48 rasters in this order: ppt1-12, tmean1-12, tmax1-12, tmin1-12
temp_scalar	multiplier to convert input temperatures to deg C
ppt_scalar	multiplier to convert input precipitation to mm
ncores	number of computing cores to use for parallel processing
already_latlong	leave as F unless rasters are already in lat-long projection
filename	output filename
m	see clusterR
...	additional arguments to clusterR or writeRaster

Value

A raster stack with 5 layers: PPT, PET, AET, CWD, RAR

References

Wang et al 2012 – ClimateWNA – Journal of Applied Meteorology and Climatology. Shuttleworth 1993 – Evaporation (chapter 4 in Handbook of Hydrology). Hargreaves and Samani 1985 – Reference Crop Evaporation from Ambient Air Temperature

matthewkling/climatica documentation built on May 17, 2019, 8:21 p.m.