Sains Malaysiana 39(3)(2010): 387–393

Finding the Best Circular Distribution for Southwesterly

Monsoon Wind Direction in Malaysia

(Menentukan Taburan Berarah Terbaik bagi Data Arah Angin Barat Daya di Malaysia)

Nur Arina Basilah Kamisan, Abdul Ghapor Hussin* & Yong Zulina Zubairi

Centre for Foundation Studies in Science, University of Malaya 50603 Kuala Lumpur, Malaysia

Received: 12 June 2009 / Accepted: 27August 2009

ABSTRACT

In this paper, four types of circular probability distribution were used to evaluate which circular probability distribution gives the best fitting for southwesterly Malaysian wind direction data, namely circular uniform distribution, von Mises distribution, wrapped-normal distribution and wrapped-Cauchy distribution. The four locations chosen were Alor Setar, Langkawi, Melaka and Senai. Two performance indicators or goodness of fit tests which are mean circular distance and chord length were used to test which distribution give the best fitting.

Keywords: Circular probability distribution; chord length; directional data; goodness of fit test; mean circular distance

ABSTRAK

Dalam kajian ini, empat jenis taburan kebarangkalian berarah telah digunakan untuk melihat taburan yang memberikan keserasian yang terbaik dengan data arah angin di Malaysia. Taburan tersebut adalah taburan berarah seragam, taburan von Mises, taburan normal–menggulung dan taburan Cauchy-menggulung. Empat lokasi di Malaysia telah dipilih untuk kajian ini iaitu di Alor Setar, Langkawi, Melaka dan Senai. Dua jenis penentu prestasi iaitu jarak min membulat dan panjang perentas telah digunakan untuk melihat taburan yang memberikan prestasi terbaik.

Kata kunci: Data berarah; jarak min membulat; panjang perentas; taburan kebarangkalian berarah; ujian keserasian Terbaik

REFERENCES

Henry, C.T. 2002. Testing for Normality. New York: Marcel Dekker.

Jamalamadaka, S.R. & SenGupta A. 2001. Topics in Circular Statistics. Singapore: World Scientific Publishing Co. Pte. Ltd.

Mardia, K.V. & Jupp, P. E. 1999. Directional Statistics. England: John Wiley, Chichester.

*Corresponding author; email: ghapor@um.edu.my