Computing grassland and forest fire behaviour, relative humidity and drought index by pocket calculator

Summary A Fire Danger (FD) program for a pocket-sized calculator has been developed to provide easy and rapid calculation of McArthur's fire danger indices for grassland and forest fires, a hazard rating and other measures of fire behaviour, together with rederived ancillary computations of a drought index and relative humidity. This allows the replacement of a number of slide rules, charts, and forms with a single small package which can be used rapidly and accurately in the field or office for research or daily operations. The program has initially been designed for an HP-41C calculator using RP notation and a continuous memory. However no programming skills are required to use the program. The computations are suitable for use by any programmable calculator or computer with a memory of about 2000 bytes. Relative humidity and the fire danger can be projected forward using current or forecast.conditions of atmospheric moisture and a forecast of temperature. The equations which were used are appended.