Browsing by Author "Rossita M. Yunus"

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    Assessment of water quality parameters using multivariate analysis for Klang River basin, Malaysia
    (Springer, 2015) Ibrahim Mohamed; Faridah Othman; Adriana I. N. Ibrahim; M. E. Alaa-Eldin; Rossita M. Yunus
    This case study uses several univariate and multivariate statistical techniques to evaluate and interpret a water quality data set obtained from the Klang River basin located within the state of Selangor and the Federal Territory of Kuala Lumpur, Malaysia. The river drains an area of 1,288 km2, from the steep mountain rainforests of the main Central Range along Peninsular Malaysia to the river mouth in Port Klang, into the Straits of Malacca. Water quality was monitored at 20 stations, nine of which are situated along the main river and 11 along six tributaries.
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    The impact of El Niño Southern Oscillation on space time PM10 levels in Peninsular Malaysia: the hierarchical spatio-temporal autoregressive models approach
    (Springer, 2022) Maizatul F. Zulkifi; Rossita M. Yunus
    Hierarchical spatio-temporal autoregressive models are useful to understand the impact of predictors on a spatio-temporal-dependent variable. This study aims to fit the model to monthly PM10 concentration using potential predictors from 33 monitoring stations within Peninsular Malaysia from 2006 to 2015 and predict the space-time data spatially and temporally. Using Monte Carlo Markov Chain (MCMC), spatial predictions are obtained based on the posterior and predictive distributions of the model. The posterior distribution of the model that is without covariates exhibits a strong temporal correlation between successive months and also a strong spatial correlation with an efective range of 300 km. Spatio-temporal models were ftted to the data with a sine term, a cosine term, and a lagged El Niño Southern Oscillation (ENSO) index as predictors. Of the 33 monitoring sites, 8 were selected randomly for validation sets.