Weather response functions — mwi

The three functions from which the Mosquito Weather Index is built. Each maps one weather variable onto a suitability multiplier in [0, 1], where 0 means the variable is outside the range in which adult mosquitoes are taken to be active and 1 means it is in the most favourable part of that range.

Usage

mwi_temperature(temperature)

mwi_humidity(humidity)

mwi_wind(wind_speed, units = c("km/h", "m/s"))

Arguments

temperature: Numeric vector of air temperatures in degrees Celsius.
humidity: Numeric vector of relative humidities in percent (0-100).
wind_speed: Numeric vector of wind speeds, in the units given by units.
units: Units of wind_speed: "km/h" (the default) or "m/s".

Value

A numeric vector the same length as the input, with values in [0, 1].

Details

mwi_temperature() is a trapezoid: zero at or below 15 degrees Celsius, rising linearly to one at 20, flat between 20 and 25, falling linearly back to zero at 30, and zero above 30.

mwi_humidity() rises linearly from zero at 40% relative humidity to one at 95%, and is zero outside that band. Note that the drop above 95% is a step, not a taper: 95% gives 1 and 95.1% gives 0. This is intentional and matches the operational definition of the index.

mwi_wind() is a cut-off rather than a gradient: one at or below 6 m/s (21.6 km/h) and zero above it.

All three are vectorised and propagate NA.

References

Developed under the LIFE CONOPS project (LIFE12 ENV/GR/000466) by the Benaki Phytopathological Institute and the National Observatory of Athens.

Examples

mwi_temperature(c(10, 15, 17.5, 22, 27.5, 30, 35))
#> [1] 0.0 0.0 0.5 1.0 0.5 0.0 0.0
mwi_humidity(c(30, 40, 67.5, 95, 96))
#> [1] 0.0 0.0 0.5 1.0 0.0
mwi_wind(c(10, 21.6, 25))
#> [1] 1 1 0
mwi_wind(c(3, 6, 8), units = "m/s")
#> [1] 1 1 0