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Papers by fadli nauval

Springer proceedings in physics, 2023

The measured raindrop size distribution (DSD) and the ITU-R model have been used to elucidate the... more The measured raindrop size distribution (DSD) and the ITU-R model have been used to elucidate the characteristics of rain attenuation in Indonesia, for Ku-band (13.6 GHz), Ka-band (25.6 GHz), and W-band (96 GHz) frequencies. The DSDs were measured by the Parsivel Disdrometer at Kototabang, Padang, Pontianak, Manado and Biak. The DSD was modeled using the modified gamma distribution and its parameters were calculated using the moment method. Then, the rain attenuation value is calculated using the DSD measurement and gamma distibution model. For the rain attenuation value from gamma DSD is obtained that at the Ka-and W-band, the highest attenuation values is observed in Manado and Biak while at lower frequencies (Ku-band) the highest attenuation are observed in Pontianak. These are caused by the differences in DSD characteristics at each location, particularly the differences in the number of the small-sized raindrop. The differences in the DSD characteristics also affected on the ac...

Advances in Meteorology, 2021

The cold pool outflow has been previously shown to be generated by decaying Mesoscale Convective ... more The cold pool outflow has been previously shown to be generated by decaying Mesoscale Convective Complexes (MCCs) in the Maritime Continent. The cold pool also has a main role in the development processes of oceanic convective systems inducing heavy rainfall. This study investigated a cold pool event (January 1-2, 2021) related to a heavy rainfall system over the coastal region of Lampung, Southern Sumatra, within a high-resolution model simulation using a regional numerical weather prediction of the Weather Research and Forecasting (WRF) with convection permitting of 1 km spatial resolution, which was validated by satellite and radar data observations. It is important to note that the intensity, duration, timing, and structure of heavy rainfall simulated were in good agreement with satellite-observed rainfall. The results also showed that a cold pool (CP) plays an important role in inducing Mesoscale Convective Complex (MCC) and was responsible for the development of an offshore pr...

NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM2020, 2021

Clutter removal of marine radar for weather observation depends on the quality and consistency of... more Clutter removal of marine radar for weather observation depends on the quality and consistency of clutter map. the clutter removal often become difficult since echoes from hard targets are much stronger than the rain reflection. There is also constraint due to different azimuth angle of each scan line in every scanner rotation resulting inconsistent map of clutter. The effort to obtain consistent clutter map to easily distinguish the rain echoes depends on the method of signal pre-processing and pulse integration. Oversampling factor influences the target detection result as higher value enable the radar to see large object more detail. The type of LPF determines the clarity of the radar image, thus better clutter map. While the pulse integration improves probability of detection and produces better clutter removal when the radar is applied for rain observation since it can provide much stable static clutter map.

NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM2020, 2021

GSMaP and TRMM data validation was carried out with rainfall data in West Borneo. This study aims... more GSMaP and TRMM data validation was carried out with rainfall data in West Borneo. This study aims to evaluate the performance of GSMAP and TRMM in estimating daily rainfall in seven watersheds, namely Ambawang (AB), Kakap (KP), Pontianak (PT), Rasar (RS), Mandor (MD), Sebadu (SB), and Segedong. (SG). The analysis was performed using statistical analysis, error calculation, and rain event presentation. The results of the GSMaP satellite data validation against the observation data showed very high correlation values in all observation locations (R> 0.75). The similar result is also found in the TRMM data. In general, all of locations show a very small RMSE value. This indicates that the GSMaP and TRMM data tend to have a good performance in estimating rainfall in West Borneo. The relative bias values show pretty good results (<15%) except for MD both GSMaP and TRMM data. The results of the estimation of rainfall data show a tendency that GSMaP is overestimated compared to TRMM data in AB, KP, PT, RS, SB, and SG while TRMM is more representative of the actual conditions. Both GSMaP and TRMM data tend not to be able to detect rains smaller than 1 mm. Overall, the three rainfall data indicate that the percentage of the frequency of rainfall events based on six rainfall classifications in all observation locations often occurs at rainfall values of 1-10 mm.

Progress In Electromagnetics Research M, 2017

The measured raindrop size distribution (DSD) and the International Telecommunication Union Radio... more The measured raindrop size distribution (DSD) and the International Telecommunication Union Radiocommunication Sector (ITU-R) model have been used to elucidate the regional and diurnal variations of rain attenuation in Indonesia, for Ku-band (13.6 GHz), Ka-band (35.6 GHz), and Wband (96 GHz) frequencies. The DSDs were measured by the Parsivel disdrometer at Kototabang (KT; 100.32

Atmospheric Research, 2012

Disdrometer has been widely used to estimate raindrop size distribution (DSD) for broad list of a... more Disdrometer has been widely used to estimate raindrop size distribution (DSD) for broad list of application. However, it classifies or bins drops automatically into size groups and provides the DSD at nominal drop diameters that correspond to the mean of bin width. Selection of the bin width may influence shape and parameterization of DSD since the exact size of individual drop in each bin, of course, is not the same as the mean of its bin size. Therefore, we present a comprehensive follow-up of a previous studyon the effect of bin width selection of 2D-Video Distrometer data. We applied the L-moment method, along with the moment and maximum likelihood methods, to samples taken from simulated and measured gamma raindrop populations. It is found that L-moment is less sensitive to bin width selection than maximum likelihood and moment methods. The bias due to bin width selection for L-moment and maximum likelihood methods is not much influenced by the mean sample size in comparison with that of moment method. With samples from the DSD having large number of raindrop or a larger shape parameter μ, the bias due to bin width selection can be small or negligible. Using the midsize of bin as the representative value for the class (bin) of binned data (ΔD) was acceptable because it gives the parameters closer to drop-by-drop data basis than using mean, mode and median of raindrop size.

Over one hundred years of vigorous progress in tropical cyclone (TC) research, the genesis of the... more Over one hundred years of vigorous progress in tropical cyclone (TC) research, the genesis of the cyclone (hereafter, tropical cyclogenesis) is remarkable as a doubtful subject. Furthermore, predicting tropical cyclogenesis, particularly in the lesser latitude, remains a significant challenge. Therefore, understanding the complex interactions in developing tropical cyclogenesis over the region is vital to improving tropical cyclogenesis forecasting. Hence, the Indonesia Maritime Continent is a tropical cyclone-free region due to decreasing the Coriolis effect. However, Seroja TC hits Flores (8.6o S, 120o E), east Nusa Tenggara, Indonesia, on 4 April 2021, and recorded as the first TC occurred over the mainland, which brought a catastrophic disaster in the region. This study investigated the tropical cyclogenesis of Seroja by using both observational and numerical studies. The results indicate that a marine heatwave and double vortices were favorable conditions produced preconditions...

Springer proceedings in physics, 2023

The measured raindrop size distribution (DSD) and the ITU-R model have been used to elucidate the... more The measured raindrop size distribution (DSD) and the ITU-R model have been used to elucidate the characteristics of rain attenuation in Indonesia, for Ku-band (13.6 GHz), Ka-band (25.6 GHz), and W-band (96 GHz) frequencies. The DSDs were measured by the Parsivel Disdrometer at Kototabang, Padang, Pontianak, Manado and Biak. The DSD was modeled using the modified gamma distribution and its parameters were calculated using the moment method. Then, the rain attenuation value is calculated using the DSD measurement and gamma distibution model. For the rain attenuation value from gamma DSD is obtained that at the Ka-and W-band, the highest attenuation values is observed in Manado and Biak while at lower frequencies (Ku-band) the highest attenuation are observed in Pontianak. These are caused by the differences in DSD characteristics at each location, particularly the differences in the number of the small-sized raindrop. The differences in the DSD characteristics also affected on the ac...

Advances in Meteorology, 2021

The cold pool outflow has been previously shown to be generated by decaying Mesoscale Convective ... more The cold pool outflow has been previously shown to be generated by decaying Mesoscale Convective Complexes (MCCs) in the Maritime Continent. The cold pool also has a main role in the development processes of oceanic convective systems inducing heavy rainfall. This study investigated a cold pool event (January 1-2, 2021) related to a heavy rainfall system over the coastal region of Lampung, Southern Sumatra, within a high-resolution model simulation using a regional numerical weather prediction of the Weather Research and Forecasting (WRF) with convection permitting of 1 km spatial resolution, which was validated by satellite and radar data observations. It is important to note that the intensity, duration, timing, and structure of heavy rainfall simulated were in good agreement with satellite-observed rainfall. The results also showed that a cold pool (CP) plays an important role in inducing Mesoscale Convective Complex (MCC) and was responsible for the development of an offshore pr...

NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM2020, 2021

Clutter removal of marine radar for weather observation depends on the quality and consistency of... more Clutter removal of marine radar for weather observation depends on the quality and consistency of clutter map. the clutter removal often become difficult since echoes from hard targets are much stronger than the rain reflection. There is also constraint due to different azimuth angle of each scan line in every scanner rotation resulting inconsistent map of clutter. The effort to obtain consistent clutter map to easily distinguish the rain echoes depends on the method of signal pre-processing and pulse integration. Oversampling factor influences the target detection result as higher value enable the radar to see large object more detail. The type of LPF determines the clarity of the radar image, thus better clutter map. While the pulse integration improves probability of detection and produces better clutter removal when the radar is applied for rain observation since it can provide much stable static clutter map.

NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM2020, 2021

GSMaP and TRMM data validation was carried out with rainfall data in West Borneo. This study aims... more GSMaP and TRMM data validation was carried out with rainfall data in West Borneo. This study aims to evaluate the performance of GSMAP and TRMM in estimating daily rainfall in seven watersheds, namely Ambawang (AB), Kakap (KP), Pontianak (PT), Rasar (RS), Mandor (MD), Sebadu (SB), and Segedong. (SG). The analysis was performed using statistical analysis, error calculation, and rain event presentation. The results of the GSMaP satellite data validation against the observation data showed very high correlation values in all observation locations (R> 0.75). The similar result is also found in the TRMM data. In general, all of locations show a very small RMSE value. This indicates that the GSMaP and TRMM data tend to have a good performance in estimating rainfall in West Borneo. The relative bias values show pretty good results (<15%) except for MD both GSMaP and TRMM data. The results of the estimation of rainfall data show a tendency that GSMaP is overestimated compared to TRMM data in AB, KP, PT, RS, SB, and SG while TRMM is more representative of the actual conditions. Both GSMaP and TRMM data tend not to be able to detect rains smaller than 1 mm. Overall, the three rainfall data indicate that the percentage of the frequency of rainfall events based on six rainfall classifications in all observation locations often occurs at rainfall values of 1-10 mm.

Progress In Electromagnetics Research M, 2017

The measured raindrop size distribution (DSD) and the International Telecommunication Union Radio... more The measured raindrop size distribution (DSD) and the International Telecommunication Union Radiocommunication Sector (ITU-R) model have been used to elucidate the regional and diurnal variations of rain attenuation in Indonesia, for Ku-band (13.6 GHz), Ka-band (35.6 GHz), and Wband (96 GHz) frequencies. The DSDs were measured by the Parsivel disdrometer at Kototabang (KT; 100.32

Atmospheric Research, 2012

Disdrometer has been widely used to estimate raindrop size distribution (DSD) for broad list of a... more Disdrometer has been widely used to estimate raindrop size distribution (DSD) for broad list of application. However, it classifies or bins drops automatically into size groups and provides the DSD at nominal drop diameters that correspond to the mean of bin width. Selection of the bin width may influence shape and parameterization of DSD since the exact size of individual drop in each bin, of course, is not the same as the mean of its bin size. Therefore, we present a comprehensive follow-up of a previous studyon the effect of bin width selection of 2D-Video Distrometer data. We applied the L-moment method, along with the moment and maximum likelihood methods, to samples taken from simulated and measured gamma raindrop populations. It is found that L-moment is less sensitive to bin width selection than maximum likelihood and moment methods. The bias due to bin width selection for L-moment and maximum likelihood methods is not much influenced by the mean sample size in comparison with that of moment method. With samples from the DSD having large number of raindrop or a larger shape parameter μ, the bias due to bin width selection can be small or negligible. Using the midsize of bin as the representative value for the class (bin) of binned data (ΔD) was acceptable because it gives the parameters closer to drop-by-drop data basis than using mean, mode and median of raindrop size.

Over one hundred years of vigorous progress in tropical cyclone (TC) research, the genesis of the... more Over one hundred years of vigorous progress in tropical cyclone (TC) research, the genesis of the cyclone (hereafter, tropical cyclogenesis) is remarkable as a doubtful subject. Furthermore, predicting tropical cyclogenesis, particularly in the lesser latitude, remains a significant challenge. Therefore, understanding the complex interactions in developing tropical cyclogenesis over the region is vital to improving tropical cyclogenesis forecasting. Hence, the Indonesia Maritime Continent is a tropical cyclone-free region due to decreasing the Coriolis effect. However, Seroja TC hits Flores (8.6o S, 120o E), east Nusa Tenggara, Indonesia, on 4 April 2021, and recorded as the first TC occurred over the mainland, which brought a catastrophic disaster in the region. This study investigated the tropical cyclogenesis of Seroja by using both observational and numerical studies. The results indicate that a marine heatwave and double vortices were favorable conditions produced preconditions...