Journal of Oil Palm Research Vol. 32 (1) March 2020, p. 34-49 CHEAH SEE SIANG*; CHRISTOPHER TEH BOON SUNG**; MOHD RAZI ISMAIL‡ and MOHD RAFII YUSOP‡
Published Online: 5 March 2020
Hourly values of air temperature, relative humidity and solar irradiance are often not available in most of the oil palm growing areas in Malaysia, thus limiting research in studying how these weather variables affect oil palm growth and yield. Therefore, a study was carried out to determine the accuracy of some selected models to estimate hourly values of these weather variables in six major oil palm growing areas in Malaysia. Using daily maximum and minimum temperatures, hourly air temperature was estimated. Together with mean hourly dew point temperature, the estimated hourly air temperature was used to simulate hourly relative humidity which was subsequently used to estimate hourly total solar irradiance. The mean absolute error, root mean square error and Willmott’s index of agreement within a 24-hr period for air temperature ranged from 0.5°C-0.7°C, 0.6°C-1.0°C and 0.81-0.84, respectively; for relative humidity ranged from 0.8%-1.5%, 1.0%-2.0% and 0.88-0.93, respectively and for total solar irradiance ranged from 83-139 W m-2, 109-178 W m-2 and 0.66-0.75, respectively. These models thus could be used to simulate hourly air temperature, relative humidity and solar irradiance in the six major oil palm growing areas in Malaysia.KEYWORDS:
* Sime Darby Plantation Research Sdn. Bhd., KM10, Jalan Banting-Klang, 42700 Banting, Selangor, Malaysia.
** AgroBio Complex, Deparment of Land Management, Faculty of Agriculture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
‡ Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.