Estimating the velocity of pyroclastic density currents using an operational dual-PRF radar
Pyroclastic density currents are one of the deadliest hazards produced by a volcano. Understanding their dynamics and generation mechanisms is critical for developing better hazard mitigation strategies. This study presents a method for retrieving velocity profiles across a natural moving PDC, appli...
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sg-ntu-dr.10356-1619672022-10-01T23:31:08Z Estimating the velocity of pyroclastic density currents using an operational dual-PRF radar Magfira Syarifuddin Jenkins, Susanna F. Taisne, Benoit Oishi, Satoru Ahmad Basuki Iguchi, Masato Asian School of the Environment Earth Observatory of Singapore Science::Geology Velocity Profile Pyroclastic Density Currents Pyroclastic density currents are one of the deadliest hazards produced by a volcano. Understanding their dynamics and generation mechanisms is critical for developing better hazard mitigation strategies. This study presents a method for retrieving velocity profiles across a natural moving PDC, applied here to a PDC generated by collapsing column during the eruption of Sinabung Volcano, Indonesia, on 19 February 2018 at the onset time of 08:53. We used an operational dual Pulse Repetition Frequency (PRF) weather radar, located ~7.8 km to the SE of the volcano, to estimate the velocity profile components of the volcanic plume: updraft, fallout, and horizontal advection. Doppler radar data was post-processed by applying two different filters: median and Laplacian, to correct errors associated with dealiased Doppler velocities. The Laplacian filter method was more effective in correcting the dealiasing errors by producing a more continuous velocity field without over smoothing its values. Following the dealiasing process, the velocity profile components were retrieved according to radar parameters such as Doppler velocities, copolar correlation, and reflectivity intensity factor. Initially, the pyroclastic clast was released at a lower exit velocity of ~120 m/s (84 s after the onset). A maximum of ~190 m/s exit velocity was then observed at 08:57:52 (292 s after onset). Lower exit velocity in the initial phase and less than 10 m/s estimated wind speed are the main factors causing the partial collapse of the plume at ~2.5 km height above the vent. The part of the collapsing column was associated with a more than 50 dBZ reflectivity intensity factor of fallout velocity exceeding −50 m/s at 126 s after the onset. Dilute PDCs were observed until 09:09:34 (994 s after onset), moving downslope at SE sector at a maximum velocity of −84 m/s (i.e., in the direction of the radar). The extracted velocity components are essential parameters in the numerical model of PDCs and tephra dispersal, enforcing the benefit of weather radar to complement the remote monitoring system of volcanic hazards. Ministry of Education (MOE) National Research Foundation (NRF) Published version This research was supported by the Earth Observatory of Singapore via its funding from the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centres of Excellence initiative. 2022-09-27T08:41:44Z 2022-09-27T08:41:44Z 2022 Journal Article Magfira Syarifuddin, Jenkins, S. F., Taisne, B., Oishi, S., Ahmad Basuki & Iguchi, M. (2022). Estimating the velocity of pyroclastic density currents using an operational dual-PRF radar. Journal of Volcanology and Geothermal Research, 424, 107462-. https://dx.doi.org/10.1016/j.jvolgeores.2021.107462 0377-0273 https://hdl.handle.net/10356/161967 10.1016/j.jvolgeores.2021.107462 2-s2.0-85124936777 424 107462 en Journal of Volcanology and Geothermal Research © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). application/pdf |
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Science::Geology Velocity Profile Pyroclastic Density Currents Magfira Syarifuddin Jenkins, Susanna F. Taisne, Benoit Oishi, Satoru Ahmad Basuki Iguchi, Masato Estimating the velocity of pyroclastic density currents using an operational dual-PRF radar |
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Pyroclastic density currents are one of the deadliest hazards produced by a volcano. Understanding their dynamics and generation mechanisms is critical for developing better hazard mitigation strategies. This study presents a method for retrieving velocity profiles across a natural moving PDC, applied here to a PDC generated by collapsing column during the eruption of Sinabung Volcano, Indonesia, on 19 February 2018 at the onset time of 08:53. We used an operational dual Pulse Repetition Frequency (PRF) weather radar, located ~7.8 km to the SE of the volcano, to estimate the velocity profile components of the volcanic plume: updraft, fallout, and horizontal advection. Doppler radar data was post-processed by applying two different filters: median and Laplacian, to correct errors associated with dealiased Doppler velocities. The Laplacian filter method was more effective in correcting the dealiasing errors by producing a more continuous velocity field without over smoothing its values. Following the dealiasing process, the velocity profile components were retrieved according to radar parameters such as Doppler velocities, copolar correlation, and reflectivity intensity factor. Initially, the pyroclastic clast was released at a lower exit velocity of ~120 m/s (84 s after the onset). A maximum of ~190 m/s exit velocity was then observed at 08:57:52 (292 s after onset). Lower exit velocity in the initial phase and less than 10 m/s estimated wind speed are the main factors causing the partial collapse of the plume at ~2.5 km height above the vent. The part of the collapsing column was associated with a more than 50 dBZ reflectivity intensity factor of fallout velocity exceeding −50 m/s at 126 s after the onset. Dilute PDCs were observed until 09:09:34 (994 s after onset), moving downslope at SE sector at a maximum velocity of −84 m/s (i.e., in the direction of the radar). The extracted velocity components are essential parameters in the numerical model of PDCs and tephra dispersal, enforcing the benefit of weather radar to complement the remote monitoring system of volcanic hazards. |
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Asian School of the Environment |
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Asian School of the Environment Magfira Syarifuddin Jenkins, Susanna F. Taisne, Benoit Oishi, Satoru Ahmad Basuki Iguchi, Masato |
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Article |
author |
Magfira Syarifuddin Jenkins, Susanna F. Taisne, Benoit Oishi, Satoru Ahmad Basuki Iguchi, Masato |
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Magfira Syarifuddin |
title |
Estimating the velocity of pyroclastic density currents using an operational dual-PRF radar |
title_short |
Estimating the velocity of pyroclastic density currents using an operational dual-PRF radar |
title_full |
Estimating the velocity of pyroclastic density currents using an operational dual-PRF radar |
title_fullStr |
Estimating the velocity of pyroclastic density currents using an operational dual-PRF radar |
title_full_unstemmed |
Estimating the velocity of pyroclastic density currents using an operational dual-PRF radar |
title_sort |
estimating the velocity of pyroclastic density currents using an operational dual-prf radar |
publishDate |
2022 |
url |
https://hdl.handle.net/10356/161967 |
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1746219646696030208 |