The mkmonet program works on an annual basis. It expects the year for which to perform the calculations as a command line parameter. It reads files named 050109.txt, 255310.txt and 257070.txt containing the data at Akron, McCook and Red Cloud, respectively, from the current directory and writes the results to the screen.
The program extracts the daily minimum and maximum temperature and precipitation from the data file named for the station. Only the data corresponding to the current year is extracted. An error is flagged if there are missing data.
The program then calculates ETo using the Hargreaves 1985 method based on daily minimum and maximum temperature, date and station latitude. This value is then converted into an equivalent Penman ETr using a calibrated ETr/ETo ratio for each station for each month.
The potential ET is then calculated from ETr and crop coefficients derived from growing-degree-days with a season from January to December.
The daily potential ET and precipitation is accumulated to give monthly potential ET and precipitation. From these monthly values, the crop irrigation requirement (CIR) is then calculated based on the TR-21 equation using a depth of application of one inch.
The monthly CIR is used as the monthly maximum phreatophyte ET.
mkmonet 2002 > 2002.out