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Capability of GPM IMERG Products for Extreme Precipitation Analysis over the Indonesian Maritime Continent
by
Ramadhan, Ravidho
,
Marzuki, Marzuki
,
Sholihun, Sholihun
in
Accuracy
,
Annual precipitation
,
Climate
2022
Integrated Multi-satellite Retrievals for GPM (IMERG) data have been widely used to analyze extreme precipitation, but the data have never been validated for the Indonesian Maritime Continent (IMC). This study evaluated the capability of IMERG Early (E), Late (L), and Final (F) data to observe extreme rain in the IMC using the rain gauge data within five years (2016–2020). The capability of IMERG in the observation of the extreme rain index was evaluated using Kling–Gupta efficiency (KGE) matrices. The IMERG well captured climatologic characteristics of the index of annual total precipitation (PRCPTOT), number of wet days (R85p), number of very wet days (R95p), number of rainy days (R1mm), number of heavy rain days (R10mm), number of very heavy rain days (R20mm), consecutive dry days (CDD), and max 5-day precipitation (RX5day), indicated by KGE value >0.4. Moderate performance (KGE = 0–0.4) was shown in the index of the amount of very extremely wet days (R99p), the number of extremely heavy precipitation days (R50mm), max 1-day precipitation (RX1day), and Simple Daily Intensity Index (SDII). Furthermore, low performance of IMERG (KGE < 0) was observed in the consecutive wet days (CWDs) index. Of the 13 extreme rain indices evaluated, IMERG underestimated and overestimated precipitation of nine and four indexes, respectively. IMERG tends to overestimate precipitation of indexes related to low rainfall intensity (e.g., R1mm). The highest overestimation was observed in the CWD index, related to the overestimation of light rainfall and the high false alarm ratio (FAR) from the daily data. For all indices of extreme rain, IMERG showed good capability to observe extreme rain variability in the IMC. Overall, IMERG-L showed a better capability than IMERG-E and -F but with an insignificant difference. Thus, the data of IMERG-E and IMERG-L, with a more rapid latency than IMERG-F, have great potential to be used for extreme rain observation and flood modeling in the IMC.
Journal Article
Evaluation of GPM IMERG Performance Using Gauge Data over Indonesian Maritime Continent at Different Time Scales
2022
Accurate precipitation observations are crucial for water resources management and as inputs for a gamut of hydrometeorological applications. Precipitation data from Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (GPM) (IMERG) have recently been widely used to complement traditional rain gauge systems. However, the satellite precipitation data needs to be validated before being widely used in the applications and this is still missing over the Indonesian maritime continent (IMC). We conducted a validation of the IMERG product version 6 for this region. The evaluation was carried out using gauge data in the period from 2016 to 2020 for three types of IMERG: Early (E), Late (L), and Final (F) from annual, monthly, daily and hourly data. In general, the annual and monthly data from IMERG showed a good correlation with the rain gauge, with the mean correlation coefficient (CC) approximately 0.54–0.78 and 0.62–0.79, respectively. About 80% of stations in the IMC area showed a very good correlation between gauge data and IMERG-F estimates (CC = 0.7–0.9). For the daily assessment, the CC value was in the range of 0.39 to 0.44 and about 40% of stations had a correlation of 0.5–0.7. IMERG had a fairly good ability to detect daily rain in which the average probability of detection (POD) for all stations was above 0.8. However, the false alarm ratio (FAR) value is quite high (<0.5). For hourly data, IMERG’s performance was still poor with CC around 0.03–0.28. For all assessments, IMERG generally overestimated rainfall in comparison with rain gauge. The accuracy of the three types of IMERG in IMC was also influenced by season and topography. The highest and lowest CC values were observed for June–July–August and December–January–February, respectively. However, categorical statistics (POD, FAR and critical success index) did not show any clear seasonal variation. The CC value decreased with higher altitude, but with slight difference for each IMERG type. For all assessments conducted, IMERG-F generally showed the best rainfall observations in IMC, but with slightly difference from IMERG-E and IMERG-L. Thus, IMERG-E and IMERG-L data that had a faster latency than IMERG-F show potential to be used in rainfall observations in IMC.
Journal Article
Translation, Cross-Cultural Adaptation, and Validation of the Malay Version of the System Usability Scale Questionnaire for the Assessment of Mobile Apps
by
Mohamad Marzuki, Muhamad Fadhil
,
Yaacob, Najib Majdi
,
Yaacob, Nor Azwany
in
Adaptation
,
Interpreters
,
Original Paper
2018
A mobile app is a programmed system designed to be used by a target user on a mobile device. The usability of such a system refers not only to the extent to which product can be used to achieve the task that it was designed for, but also its effectiveness and efficiency, as well as user satisfaction. The System Usability Scale is one of the most commonly used questionnaires used to assess the usability of a system. The original 10-item version of System Usability Scale was developed in English and thus needs to be adapted into local languages to assess the usability of a mobile apps developed in other languages.
The aim of this study is to translate and validate (with cross-cultural adaptation) the English System Usability Scale questionnaire into Malay, the main language spoken in Malaysia. The development of a translated version will allow the usability of mobile apps to be assessed in Malay.
Forward and backward translation of the questionnaire was conducted by groups of Malay native speakers who spoke English as their second language. The final version was obtained after reconciliation and cross-cultural adaptation. The content of the Malay System Usability Scale questionnaire for mobile apps was validated by 10 experts in mobile app development. The efficacy of the questionnaire was further probed by testing the face validity on 10 mobile phone users, followed by reliability testing involving 54 mobile phone users.
The content validity index was determined to be 0.91, indicating good relevancy of the 10 items used to assess the usability of a mobile app. Calculation of the face validity index resulted in a value of 0.94, therefore indicating that the questionnaire was easily understood by the users. Reliability testing showed a Cronbach alpha value of .85 (95% CI 0.79-0.91) indicating that the translated System Usability Scale questionnaire is a reliable tool for the assessment of usability of a mobile app.
The Malay System Usability Scale questionnaire is a valid and reliable tool to assess the usability of mobile app in Malaysia.
Journal Article
Rainfall Climatology Associated with Cyclonic and Non-Cyclonic Events in Indonesia’s New Capital Based on IMERG and IBTrACS
by
Marzuki, Marzuki
,
Ananda, Nadya Rezky
,
Yusnaini, Helmi
in
Annual precipitation
,
Annual rainfall
,
Climatology
2025
The Nusantara Capital City (NCC) is susceptible to extreme rainfall influenced by large scale atmospheric systems, including tropical cyclones (TCs) from the Western Pacific Ocean. This study examines TC contributions to rainfall in NCC from 2000 to 2024 using IBTrACS cyclone track data, IMERG daily rainfall, and ERA5 atmospheric reanalysis. The objective synoptic analysis technique was used to isolate TC induced rainfall based on a 1100 km radius and a ±3 day window from peak cyclone intensity. Results show that non-TC rainfall dominates accounting for over 88% of NCC annual precipitation, while indirect TC influence contributes less than 12%. Dynamically, TC related rainfall occurs under specific atmospheric conditions, sea surface temperatures above 27 °C, high relative humidity above 85%, and strong positive vorticity which are generally absent during non-TC periods. Trend analysis indicates an increase in total annual rainfall in NCC primarily driven by an increase in non-TC rainfall of 10 mm/year, while TC related rainfall shows a decreasing trend of 5 mm/year. These findings underscore that long-term rainfall patterns in NCC are mostly shaped by regional weather variability rather than TC, highlighting the importance of adaptive climate strategies that focus on dominant local rainfall drivers and hydrometeorological risks.
Journal Article
An overview of nanoemulsion: concepts of development and cosmeceutical applications
by
Wahab, Roswanira Abdul
,
Che Marzuki, Nur Haziqah
,
Abdul Hamid, Mariani
in
Benchmarks
,
biotechnology
,
cosmeceutical
2019
The interest in nanoscale emulsions has considerably grown in recent decades as a consequence of their specific attributes such as high stability, attractive appearance, in addition to high performance and sensorial advantage. In fact, it nanoemulsions are one of the major popular formulation systems in the pharmaceutical and cosmeceutical fields. The thermodynamic and high kinetic stability, besides the minute droplet size of nanoemulsions have spurred their rapid development as a system for delivery of bioactive substances/drugs in cosmetics and dermatological formulations. The composition and the technique of preparation very much define the quality of nanoemulsions. They are mainly targeted at high performance, product distribution to consumers, alongside the prospects of mass production. Formulators, however, do face certain limitations especially regarding the diffusion of active ingredients into the human skin. This review describes the popular techniques used by formulators in recent years to prepare nanoemulsions as final application products for cosmeceutical application. Correspondingly, an overview of characterisation technologies to differentiate between the micro and nanoemulsions - alongside their benchmarks in terms of their physical and thermodynamic stabilities, is also described in this review.
Journal Article
Local site effects and seismic microzonation around Suban Area, Curup Rejang Lebong, Bengkulu deduced by ambient noise measurements
by
Marzuki, Marzuki
,
Siburian, Brecya Isa
,
Lubis, Ashar Muda
in
Ambient noise
,
Ambient noise measurements
,
Amplification
2024
Background
The Suban area of Curup Rejang Lebong is a tourist region in Bengkulu Province, Indonesia, close to the active Ketaun and Musi faults, which are segments of the Sumatra Fault System (SFS). However, no studies have been conducted in this area to assess how geological structures affect seismic ground motions and contribute to seismic hazard and risk assessment.
Methods
The first study of seismic microzonation in the Suban area of Curup City by ambient noise measurements was conducted at 100 sites, spaced ~ 1 km apart, with 60 min of data acquisition for each site. All microseismic data were processed using the Horizontal to Vertical Spectral Ratios (HVSR) method.
Results
The HVSR method revealed the amplification factors (
A
0
) ranging from 1.23 to 8.26 times, corresponding to natural frequency (
f
0
) variations between 1.24 and 9.67 Hz. About 13% and 55% of the sites show high (6 ≤
A
0
≤ 9) and medium (3 ≤
A
0
≤ 6) amplifications, respectively, predominantly in the western parts of the study area, consistent with a high seismic vulnerability index (
K
g
). Furthermore, we also estimated the ground shear strain (GSS) of the region using the Kanai method with two large historical earthquakes at the Ketahun segment in 1943 (Mw 7.4) and the Musi segment in 1979 (Mw 6.0). The
K
g
value is consistent with the GSS values and indicates areas of severe damage during the historic earthquakes.
Conclusions
Thus, the western parts of the Suban region are vulnerable to severe damage from an earthquake. These findings could provide valuable insights for future planning and risk management efforts aimed at minimizing the impact of earthquakes in the Suban region.
Journal Article
A Preliminary Assessment of the GSMaP Version 08 Products over Indonesian Maritime Continent against Gauge Data
2023
This study is a preliminary assessment of the latest version of the Global Satellite Measurement of Precipitation (GSMaP version 08) data, which were released in December 2021, for the Indonesian Maritime Continent (IMC), using rain gauge (RG) observations from December 2021 to June 2022. Assessments were carried out with 586 rain gauge (RG) stations using a point-to-pixel approach through continuous statistical and contingency table metrics. It was found that the coefficient correlation (CC) of GSMaP version 08 products against RG observations varied between low (CC = 0.14–0.29), moderate (CC = 0.33–0.45), and good correlation (CC = 0.72–0.75), for the hourly, daily, and monthly scales with a tendency to overestimate, indicated by a positive relative bias (RB). Even though the correlation of hourly data is still low, GSMaP can still capture diurnal patterns in the IMC, as indicated by the compatibility of the estimated peak times for the precipitation amount and frequency. GSMaP data also manage to observe heavy rainfall, as indicated by the good of detection (POD) values for daily data ranging from probability 0.71 to 0.81. Such a good POD value of daily data is followed by a relatively low false alarm ratio (FAR) (FAR < 0.5). However, the GSMaP overestimates light rainfall (R < 1 mm/day); as a consequence, it overestimates the consecutive wet days (CWD) and number of days with rainfall ≥ 1 mm (R1mm) indices, and underestimates the consecutive dry days (CDD) extreme rain index. GSMaP daily data accuracy depends on IMC’s topographic conditions, especially for GSMaP real-time data. Of all GSMaP version 08 products evaluated, outperformed post-real-time non-gauge-calibrated (GSMaP_MVK), and followed by post-real-time gauge-calibrated (GSMaP_Gauge), near-real-time gauge-calibrated (GSMaP_NRT_G), near-real-time non-gauge-calibrated (GSMaP_NRT), real-time gauge-calibrated (GSMaP_Now_G), and real-time non-gauge-calibrated (GSMaP_Now). Thus, GSMaP near-real-time data have the potential for observing rainfall in IMC with faster latency.
Journal Article
3.3–4.3 GHz efficient continuous class-F gallium nitride power amplifier based on simplified real frequency technique and harmonic tuning
by
Sadeque, Md. Golam
,
Mohd Marzuki, Azah Syafiah
,
Lees, Jonathan
in
Algorithms
,
Amplifiers, Electronic
,
Bandwidths
2024
In order to implement the fifth generation (5G) communication system for a large number of users, the governments of many countries nominated the low 5G frequency band between 3.3 and 4.3 GHz. This paper proposes a wideband RFPA by designing the input matching network (MN) and output MN of the device using the simplified real frequency technique (SRFT) and the harmonic tuning network. The load-pull and source-pull is applied at multiple points for 100 MHz intervals over the bandwidth to obtain the optimum impedances at the output and input of the 10W Gallium Nitride (GaN) Cree CGH40010F device. To verify the design, the RFPA is simulated, and the performance is measured between 3.3 and 4.3 GHz. According to experimental findings, the measured drain efficiency (DE) throughout the whole bandwidth ranged from 57.5 to 67.5% at the output power of 40 dBm. Moreover, at the 1 dB compression point between 39.2 and 42.2 dBm output power, the drain efficiency (DE) achieves a high value of 81.2% with an output power of 42.2 dBm at a frequency of 3.3 GHz. The RFPA can obtain a maximum gain of 12.4 dB at 3.5 GHz. The linearity of the RFPA with a two-tone signal is measured and the value is less than -22 dBc all over the band.
Journal Article
Field Survey of the 2018 Sulawesi Tsunami: Inundation and Run-up Heights and Damage to Coastal Communities
by
Krautwald, Clemens
,
Takabatake, Tomoyuki
,
Marzuki, Abdul Gafur
in
Alliances
,
Coastal zone
,
Coastal zone management
2019
On September 28, 2018, a large earthquake and its accompanying tsunami waves caused severe damage to the coastal area of Palu Bay, in the central western part of Sulawesi Island, Indonesia. To clarify the distribution of tsunami inundation and run-up heights, and damage to coastal communities due to the tsunami, the authors conducted a field survey 1 month after the event. In the inner part of Palu Bay tsunami inundation and run-up heights of more than 4 m were measured at many locations, and severe damage by the tsunami to coastal low-lying settlements was observed. In the areas to the north of the bay and around its entrance the tsunami inundation and run-up heights were lower than in the inner part of the bay. The tsunami inundation distance depended on the topographical features of coastal areas. The southern shore of the bay experienced a longer inundation distance than other shores, though generally severe damage to houses was limited to within around 200 m from the shoreline. The main lessons that can be learnt from the present event are also discussed.
Journal Article