Nuurul Hudaa Mohd Sobli

Assessment of Statistical and Empirical Conversion Methods of Integration Time for Rainfall Rate in Malaysia

This paper presents some preliminary observations of assessments regarding the precipitation intensity conversion methods from 60- to 1-min integration time. There are two conversion methods were identified and used for this findings; Rice-Holmberg and Khairolanuar et al. conversion methods. Different type of precipitation were analyzed and implemented in analytical method of Rice-Holmberg and characteristics of rainfall rate distributions were evaluated from the empirical method of Khairolanuar et al. Rainfall intensity data were acquired from Malaysia Meteorological Department (MMD). The rainfall rate data consist of twelve consecutive months from January to December 2009. The evaluations for the acquired data were carried out to produce annual rainfall rate cumulative distribution and as well as its cumulative distribution at 1-min integration time utilizing the aforementioned conversion methods. The comparisons of the performance of these two methods were also examined. Based on the evaluation, it can be observed that Rice-Holmberg and Khairolanuar et al. produced percentage errors around 19 % as compared to ITU-R P.837 at 0.01 % of time exceedance.

Comparison of Conversion Methods from 60- to 1-min Integration Time for Rainfall in Malaysia

This paper presents some preliminary assessments of the precipitation rate conversion methods from 60-min to 1-min integration time. The conversion methods used in this study are Moupfouma and Khairolanuar et al., and ITU-R P.837. Rainfall rate data of twelve-months duration from January to December 2009 were acquired from Malaysia Meteorological Department (MMD) and exploited for the evaluation. The rainfall data were collected from MMD rain gauge station located at Kuala Lumpur International Airport (KLIA). The investigations comprise of producing annual rainfall rate cumulative distributions of the measured data. The equivalent 1-min annual rainfall rate cumulative distributions using conversion methods as mentioned above. Predicted values of annual 1-min cumulative distribution established by ITU-R P.837 are used as references. The equivalent 1-min equivalent cumulative distribution obtained from Moupfouma’s and Khairolanuar et al.’s methods are then compared with that of ITU-R P.837 to validate the applicability and efficiency of each method. According to the results, it can be observed that Khairolanuar et al.’s method capable of generating equivalent 1-min rainfall values with smallest percentage difference as compared to ITU-R P.837 at 0.01 % of time exceedance.

Analyses of meteorology information during Malaysian flood disaster 2014

In this paper, we analyze the rain gauge data and radar data in the duration of time, T over the area covered by meteorological radar and rain gauge. T can be the whole duration for the rain event before, during and after the flood tragedy. The procedure is applied to a set of data composed of Constant Altitude Plan Position (CAPPI) scans for the absolute size of cloud from weather radar and rainfall measurement provided by rain gauge data. The procedure was applied to 14 days precipitation phenomenon observed in Kota Bharu, Kelantan (Malaysia) from 13 December 2014 until 26 December 2014. The objective of the research is to derive the tropical flood estimation model.

Assessment of Conversion Methods to Acquire 1-Minute Integration Time Rain Intensity Statistic

This paper presents some preliminary findings of assessments carried out pertaining to the applicability of rain intensity conversion methods. Five conversion methods were identified in this study namely the ITU-R, Segal, Burgeuno, Chebil-Rahman and Khairolanuar et al. 1 year of rain intensity data were acquired from the Malaysian Meteorological Department (MMD) and utilized in the investigation. The research methodology involves productions of annual rain intensity cumulative distributions at 1-minute integration time using mentioned conversion methods. Predicted values established by ITU-R are used as benchmark. The values are then compared with values acquired using other conversion methods; in order to validate the applicability and effectiveness of each method. Based on the evaluation, it can be observed that the Khairolanuar et al. method seems to be a befitting conversion method and capable of generating values with smallest percentage difference.

Initial assessment of radar reflectivity-rainfall rate, Z-R relationships for moderate rain events in Malaysia

Various associations between radar reflectivity (Z) and rainfall rate (R), identified as Z-R relationships have been derived to facilitate the rainfall rate estimation by weather radar. Most of the previously proposed Z-R relationships were implied as too generalized and only applicable within the region that has identical climate characteristics or behavior. Based on such notion, the most accurate Z-R relationship applicable for Malaysian weather radar therefore needs to be investigated and identified. In this paper, two renowned models will be evaluated on how well they fit to Malaysian weather radar data. Preliminary comparisons between the previously proposed Z-R relationships using newly acquired radar data in Malaysia and ground-based rain gauge measurements are also presented. The use of inaccurate relationship can cause error in radar rainfall estimates. This might pose unacceptable risk for the aviation industry where accurate, dependable weather information deduced by radar system is expected at all times.

Comparison of Radar Derived Rain Attenuation with the RazakSAT's X-Band Link Signal Measurement

Abstract—The preliminary analysis involving comparison between radar derived attenuation using an S-band meteorological radar and measured signal of RazakSAT’s X-band satellite link is presented. The radar data employed was attained from the Malaysian Meteorological Department’s (MMD) terminal Doppler weather radar installed strategically in the vicinity of Kuala Lumpur International Airport (KLIA). The X-band (8 GHz) satellite-Earth signals of Malaysian RazatSat’s collected at the National Space Agency (NSA) space center have been analyzed and studied. The vertical polarization S-band radar reflectivity information was used to calculate the likely rain attenuation along the RazakSAT satellite propagation paths. This was carried out by first converting the radar reflectivity values into rainfall rate using the established Z-R relations of Marshall-Palmer equation and, afterwards, by evaluating the slant path attenuation through the assimilation of the specific rain attenuation derived at the rainfall rate.