Perkembangan pembangunan bersama dengan peningkatan penduduk dan peningkatan penggunaan pengangkutan telah menyumbang dalam menurunkan kualiti udara di Malaysia. Tujuan kajian ini adalah untuk meramal dan memodelkan hubungan diantara pembolehubah linear dan pembolehubah membulat dengan menggunakan fungsi ketumpatan kebarangkalian dan analisis regresi. Pemerhatian dilakukan di stesen Shah Alam, Prai, Pasir Gudang dan Jerantut dalam tempoh sepuluh tahun dari tahun 2004 hingga 2013. Nilai min bagi kepekatan O3 untuk semua lokasi tidak melebihi had MAAQG. Ketumpatan membulat dan rajah angin telah digunakan untuk menunjukkan ciri arah angin termasuk arah min, min panjang paduan dan penumpuan. Kajian ini mencadangkan kehadiran angin yang menonjol telah bertiup dari utara dan arah selatan Semenanjung Malaysia disebabkan oleh monsun timur laut dan monsun barat daya. Empat fungsi taburan disuaikan dengan data arah angin dan telah mendapati bahawa taburan Cauchy membungkus menunjukkan prestasi yang baik berdasarkan analisis purata panjang perentas. Analisis diteruskan dengan korelasi linear-membulat, regresi linear-membulat dan regresi linear berganda. Kebanyakkan korelasi positif ditemui antara arah angin dan kepekatan O3 di semua stesen pada waktu siang dan malam. Dari regresi linear-membulat, kepekatan O3 telah diramalkan dari arah angin dan keputusan menunjukkan bahawa beberapa bacaan di stesen Shah Alam melebihi had yang telah dibenarkan MAAQG (0.06 ppm). Model ramalan diteruskan dengan regresi linear berganda dengan memasukkan sinus dan kosinus arah angin sebagai pembolehubah tak bersandar berserta dengan kelajuan angin. Didapati bahawa model ramalan sebelah malam memberikan ketepatan yang tinggi berbanding dengan waktu siang.
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The rapid development along with increased population and transportation usage has deteriorated air quality status in Malaysia. The purpose of this research is to predict and modelling the casual relationship between circular and linear variables using probability density functions and regression analysis. The observations were made at Shah Alam, Prai, Pasir Gudang and Jerantut station over ten years period from 2004 until 2013 respectively. Mean values for O3 concentrations at all locations did not exceed MAAQG level limit. Circular density and wind rose plot were used to describe the characteristics of wind direction including mean direction, mean resultant length and concentration. This study suggested the presence of prominent wind that were blowing from north and south direction of Peninsular Malaysia due to southwest monsoon and northeast monsoon. Four distributions function were fitted to the wind direction data and it was found that wrapped Cauchy fit the data very well based on mean chord length. The analysis was further conducted with circular-linear correlation, circular-linear regression and multi linear regression model. Most of positive correlations were found between wind direction and O3 concentration in all stations during daytime and nightime. From the circular – linear regression, O3 concentration were predicted from wind direction and the results showed that few values in Shah Alam station exceeded the permissible limit by MAAQG (0.06 ppm). Prediction model were continued with multi linear regression by including the sine and cosine of wind direction as independent variables as well as wind speed variable. It was found that nighttime models provide better accuracy than daytime.
Circular statistical analysis of wind direction and wind speed on ozone concentration_Noorain Zinol_A9_2017_MYMY