Abstract:
Humidity is among one of the most important weather conditions that influence salt
preparation. Technical processes and treatments carried out in salt factories and laboratories
require relative humidity levels to be maintained using control systems. Puttalam is a reputed
saltern in Sri Lanka. The knowledge on the fluctuations of relative humidity is paramount
for the management of Puttalam saltern, to carry out their activities in a proper manner.
This paper presents the results of a study carried out to develop a prediction model for
relative humidity during night time in Puttalam saltern, using Box-Jenkins methodology.
This study is based on percentage mean relative humidity data collected from the Puttalam
weather station from January 1998 to December 2007. Sample autocorrelation functions
and sample partial autocorrelation functions are used as the major diagnostic tools in this
model building procedure. Model parameters were estimated using the non-linear least
squares method. The adequacy of the fitted model was checked by analyzing the residuals.
According to the analysis it was revealed that the ARIMA (1, 0, 1) (1, 1, 1\2 model is the
best model that could be used to forecast the percentage mean relative humidity at Puttalam
saltern during night time.
Forecasts can be readily generated using the above model up to a period of twelve months
without using any external variables.
