Characterization of lightning-generated electric fields and development of automated measuring system for cloud-to-ground lightning in Malaysia

Lightning flash produces electric discharges naturally into atmosphere which somehow result in negative consequences especially to power, electronic and communication systems. Hence, the knowledge of such characteristic is crucial to be obtained to fulfil the task of mitigating lightning problems that may occur. Furthermore, most studies regarding this were done in the temperate and sub-tropical regions manually which time consuming for analysing a timeframe purposes. This is due to the reason that an automated system is not available in the present market. Thus, this study is aimed to produce an automated measuring system for cloud-to-ground in Malaysia in order to reduce the analysed time. Measurements of the generated electric fields were done using parallel plate antenna system from May to October 2013 at Universiti Putra Malaysia, Serdang, Selangor, Malaysia, where the measurement site has a geographical coordinate of 2°59'19.9"N latitude and 101°43'29.8"E longitude. It is known that Malaysia is generally a tropical climate country with maximum monsoon rain occurring from October to December due to southwest monsoon and inter monsoon period. This thesis presents the characteristics of cloud-to-ground lightning generated vertical electric field waveforms recorded in Malaysia using Automated Characterisation of Lightning Electric Fields–Center of Electromagnetic and Lightning Protection (ACLEF-CELP). A total of 142 return strokes of negative lightning and 34 return strokes of positive lightning were found during the measurement period, and with preliminary breakdown pulses. The main purpose of this study includes characterisations of 12 and 4 types criteria to be considered for return stroke and preliminary breakdown pulses, respectively. Analysis of the measured cloud-to-ground lightning data is done using Matlab software which is used to analyse the data and serves as a database. It is found that, the initial peaks of electric field and its derivative for first return strokes are larger than those for the subsequent return strokes for both positive and negative return strokes. Data were analysed using ACLEF-CELP system and compared to another set of data with a similar climate condition. Both manual and automated data were compared and it is found that they are compatible with each other. Also, comparison of overall results with published data such as from Sri Lanka, Sweden, Germany, Japan and United States of America shows that several electric field and its derivative parameters are affected by geographical region. The ACLEF-CELP system could reduce analysis time where cloud-to-ground lightning data could be easily characterized with increment of efficiency. This is important specially when dealing with numerous data such as from a cloud-to-ground lightning.

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