r.bioclim - GRASS GIS manual

Note: This document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade, and read the current manual page.

NAME

r.bioclim - Calculates bioclimatic indices.

KEYWORDS

raster, time series

SYNOPSIS

r.bioclim

r.bioclim --help

r.bioclim tmin=name[,name,...] tmax=name[,name,...] [tavg=name[,name,...]] [precipitation=name[,name,...]] output=string [tinscale=integer] [toutscale=integer] [quartals=integer] [workers=integer] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

--overwrite: Allow output files to overwrite existing files
--help: Print usage summary
--verbose: Verbose module output
--quiet: Quiet module output
--ui: Force launching GUI dialog

Parameters:

tmin=name[,name,...] [required]: Monthly minimum temperatures; Monthly minimum temperatures for 12 months
tmax=name[,name,...] [required]: Monthly maximum temperatures; Monthly maximum temperatures for 12 months
tavg=name[,name,...]: Monthly average temperatures; Monthly average temperatures for 12 months
precipitation=name[,name,...]: Monthly precipitation; Monthly average precipitation for 12 months
output=string [required]: Prefix for output maps
tinscale=integer: Scale factor for input temperature; Default: 1
toutscale=integer: Scale factor for output temperature; Default: 10
quartals=integer: Number of quartals to use; Options: 4, 12; Default: 4
workers=integer: Number of parallel processes to launch; Options: 1-12; Default: 1

DESCRIPTION
NOTES
EXAMPLES
SEE ALSO
REFERENCES
AUTHOR

DESCRIPTION

r.bioclim calculates various bioclimatic indices from monthly temperature and optional precipitation time series. The time series can be averages for several years or monthly values for a specific year. In any case all 12 months must be provided. If a precipitation time series is not provided, only those indices based on temperature are calculated. The names of the output maps are <output>bio01, <output>bio02, <output>bio03, etc. If the suffix bioXY needs to be separated from the output prefix, that separator must be part of the prefix, e.g. output=eurolst_.

If the input temperatures are scaled, e.g. as input = Celsius * 10, then the inscale option must be set to 10. Similarly, the outscale option is by default 10, and temperature output is in this case Celsius * 10. Exceptions are BIO3, BIO4, and BIO15 which are always multiplied by 100 (see below). The reason that outscale is set to 10 by default is that the output layers are integers (for compatibility with WORLDCLIM), and a scaling factor of 10 (or higher power of 10) ensures a minimum of precision.

NOTES

Quarter years

The bioclimatic indices referring to the wettest, driest, warmest or coldest quarter can be computed in two different ways. The default is to divide a year into four quarters (quarters=4). Using this option the first quarter refers to Jan - Mar, the second quarter to Apr - Jun, and the last quarter to Oct - Dec. It is the method used to create the 250 m EuroLST bioclim data and should be used with records for a specific year.

The second option is to divide the year in 12 quarters. With this option the quarterly parameters are not aligned to any calendar quarters. Instead, the first quarter refers to Jan - Mar, the second quarter to Feb - Apr, and the last quarter to Dec - Feb. This is the same method as used by the biovars function in the R package dismo and how the bioclimatic variables provided by Worldclim were computed. This option should be used when long-term averages are used as input.

Precipitation data

Check the unit of measure of precipitation data. To calculate the bio18 and bio19 r.bioclim rounds the value of the raster to the closest integer value. If the unit of measure of your data is, for example, kg m-2 m-1 (i.e., fluxes per second) as in CHELSA data you will gain a raster map with zero values for the bio18 and bio19, because the precipitation values are very close to 0.

List of bioclimatic indices

BIO 01 Annual mean temperature as the mean of the monthly temperatures (°C)

BIO 02 Mean diurnal range as the mean of monthly (max temp - min temp) (°C)

BIO 03 Isothermality (BIO2/BIO7 * 100)

BIO 04 Temperature Seasonality (standard deviation * 100)

BIO 05 Max Temperature of Warmest Month (°C)

BIO 06 Min Temperature of Coldest Month (°C)

BIO 07 Temperature Annual Range (BIO5 - BIO6) (°C)

BIO 08 Mean Temperature of Wettest Quarter (°C)

BIO 09 Mean Temperature of Driest Quarter (°C)

BIO 10 Mean Temperature of Warmest Quarter (°C)

BIO 11 Mean Temperature of Coldest Quarter (°C)

BIO 12 Annual Precipitation (mm)

BIO 13 Precipitation of Wettest Month (mm)

BIO 14 Precipitation of Driest Month (mm)

BIO 15 Precipitation Seasonality (Coefficient of Variation * 100)

BIO 16 Precipitation of Wettest Quarter (mm)

BIO 17 Precipitation of Driest Quarter (mm)

BIO 18 Precipitation of Warmest Quarter (mm)

BIO 19 Precipitation of Coldest Quarter (mm)

EXAMPLES

Bioclimatic indices from worldclim data with 4 parallel processes:

r.bioclim tmin=`g.list type=rast pat=tmin_* map=. sep=,` \
          tmax=`g.list type=rast pat=tmax_* map=. sep=,` \
          prec=`g.list type=rast pat=prec_* map=. sep=,` \
          out=worldclim_ workers=4