cold_mileage: Fraction of mileage driven with a cold engine or catalizer below normal temperature
Description
This function depends length of trip and on ambient temperature.
From the guidelines EMEP/EEA air pollutant emission inventory guidebook
http://www.eea.europa.eu/themes/air/emep-eea-air-pollutant-emission-inventory-guidebook
Usage
cold_mileage(ltrip, ta)
Arguments
ltrip
Numeric; Length of trip. It must be in 'units' km.
ta
Numeric or data.frame; average monthly temperature Celsius. It if is a
data.frame, it is convenient that each column is each month.