VM-ADCP backscatter data management using QGIS

2020 ◽  
Author(s):  
Paola Picco ◽  
Roberto Nardini ◽  
Sara Pensieri ◽  
Roberto Bozzano ◽  
Luca Repetti ◽  
...  
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Relevant Information ◽  
Ocean Currents ◽  
Acoustic Backscatter ◽  
Ligurian Sea ◽  
Current Profiler ◽  
High Backscatter ◽  
Set Up ◽  
High Resolution Bathymetry ◽  
Sampling Set

<p>VM-ADCP (Vessel Mounted Acoustic Doppler Current Profiler) are regularly operating on board of several research vessels with the aim of providing 3-D ocean currents fields. Along with ocean currents, these instruments also measure acoustic backscatter profile on a known frequency, that can be of great advantages for other environmental investigations such as the zooplankton migrations. The presence of zooplankton can be detected by a variation of acoustic backscatter changing  with the depth at a periodic (diurnal or semidiurnal) variability, related to the vertical  migration of these organisms. GIS has proven to be a powerful tool to manage the huge amount of VM-ADCP backscatter data obtained during the oceanographic campaigns. Moreover, this allows to extract relevant information on zooplankton distribution and abundance, even when the monitoring strategy of the experiment does not completely meet the temporal and spatial resolution required for these studies. The application here described has been developed on QGIS and tested on the Ligurian Sea (Mediterranean Sea). In order to obtain the comparability of data from instruments operating at different frequencies and sampling set-up, echo intensity data are converted into volume backscatter strength and corrected for the slant-range. Using high-resolution bathymetry rasters acquired and processed by the Italian Hydrographic Institute, allows to discard the anomalous high backscatter values due to presence of the bottom. Another advantage of the GIS is the possibility to easily identify night-collected data from the daily ones and their spatial distribution, as well as those from the surface and the deeper layer. All the possible combinations can be then visualised and analysed.</p>

scholarly journals Pasang Surut, Arus dan Gelombang Berdasarkan Data Pengukuran Acoustic Doppler Current Profiler di Perairan Pulau Cilik, Karimunjawa

2020 ◽  
Vol 9 (1) ◽  
pp. 37-44
Author(s):  
Elis Indrayanti ◽  
Diah Permata Wijayanti ◽  
Hendry Syahputra Ropinus Siagian
Keyword(s):  
Coral Cover ◽  
Measurement Data ◽  
Acoustic Doppler Current Profiler ◽  
Ocean Currents ◽  
Time Interval ◽  
Live Coral ◽  
Actual Measurement ◽  
M 10 ◽  
Current Profiler ◽  
Sample Rate

Pulau Cilik merupakan gugusan pulau di Karimunjawa yang menjadi salah satu destinasi wisata bahari di Indonesia. Perairan ini kaya akan terumbu karang dan ikan berwarna-warni dengan  tutupan karang hidup yang masih tinggi. Proses hidrodinamika seperti pasang surut, arus laut dan gelombang laut secara langsung maupun tidak langsung berpengaruh terhadap kondisi terumbu karang, oleh karena itu penelitian ini perlu dilakukan. Tujuan penelitian adalah untuk mengetahui karakteristik pasang surut, arus laut dan gelombang berdasarkan data pengukuran Acoustic Doppler Current Profiler (ADCP) di Perairan Pulau Cilik, Karimunjawa. Pengukuran dilaksanakan selama 7x24 jam dengan interval waktu 600 dt dan sample rate 300 dt. Posisi ADCP pada -5.8177°S  dan 110.5096°E. Kedalaman total pengukuran 14 m dengan kedalaman aktif pengukuran 12 m, yang terbagi menjadi 6 lapisan kedalaman yaitu 2 m, 4 m, 6 m, 8 m, 10 m, dan 12 m.  Hasil pengukuran menunjukkan bahwa Perairan Pulau Cilik, Karimunjawa memiliki tipe pasang surut campuran condong harian tunggal dengan nilai formzahl sebesar 2.55. Kecepatan arus bervariasi dengan rata-rata pada seluruh lapisan antara 5.57–6.35 cm/dt, sedangkan arahnya bi-directional yaitu memiliki dua muka arah (timur dan barat-barat daya). Tinggi dan periode gelombang yang didapatkan pada saat pengamatan relatif kecil. Cilik Island Waters in Karimunjawa is one of the marine tourism destinations in Indonesia. These waters are rich in coral reefs and colorful fish with high live coral cover. Hydrodynamic processes as tides, ocean currents, and waves influence the performance of coral reef through direct or indirect effects. Therefore this research needs to be done. The purpose of this study was to determine the characteristics of tides, ocean currents, and waves based on Acoustic Doppler Current Profiler (ADCP) measurement data in Cilik Island Waters, Karimunjawa. Measurements were carried out for 7 x 24 hours (2 April 2017 - 9 April 2017) with a time interval of 600 s and a sample rate of 300 s. The ADCP position is -5.8177 ° S and 110.5096 ° E. The total depth is 14 m with an actual measurement depth of 12 m, which is divided into 6 layers of depth namely 2 m, 4 m, 6 m, 8 m, 10 m, and 12 m. Result shown that  Cilik Island, Karimunjawa, have a single mixed daily tidal type with a formzahl value of 2.55. Current velocity varies with the average in all layers between 5.57-6.35 cm/s, while the direction is bi-directional, which has two faces (east and west-southwest). The height and wave period obtained at the time of observation are relatively small. 

scholarly journals Temporal variations of zooplankton biomass in the Ligurian Sea inferred from long time series of ADCP data

Ocean Science ◽  
2014 ◽  
Vol 10 (1) ◽  
pp. 93-105 ◽  
Author(s):  
R. Bozzano ◽  
E. Fanelli ◽  
S. Pensieri ◽  
P. Picco ◽  
M. E. Schiano
Keyword(s):  
Time Series ◽  
Acoustic Doppler Current Profiler ◽  
Temporal Variations ◽  
Zooplankton Biomass ◽  
Mesopelagic Fish ◽  
Ligurian Sea ◽  
Time Frequency ◽  
Backscattering Strength ◽  
Current Profiler ◽  
Long Time

Abstract. Three years of 300 kHz acoustic doppler current profiler data collected in the central Ligurian Sea are analysed to investigate the variability of the zooplankton biomass and the diel vertical migration in the upper thermocline. After a pre-processing phase aimed at avoiding the slant range attenuation, hourly volume backscattering strength time series are obtained. Despite the lack of concurrent net samples collection, different migration patterns are identified and their temporal variability examined by means of time–frequency analysis. The effect of changes in the environmental condition is also investigated. The highest zooplankton biomasses are observed in April–May just after the peak of surface primary production in March–April. The main migration pattern found here points to a "nocturnal" migration, with zooplankton organisms occurring deeper in the water column during the day and shallower at night. Also, twilight migration is highlighted during this study. The largest migrations are recorded in November–December, corresponding to lowest backscattering strength values and they are likely attributable to larger and more active organisms (i.e. euphausiids and mesopelagic fish). The results suggest further applications of the available historical acoustic doppler current profiler time series.

Seasonal changes in the diel vertical migration of Chaoborus punctipennis larval instars

2014 ◽  
Vol 71 (5) ◽  
pp. 665-674 ◽  
Author(s):  
Lauren Emily Barth ◽  
W. Gary Sprules ◽  
Mathew Wells ◽  
Melissa Coman
Keyword(s):  
Vertical Migration ◽  
Diel Vertical Migration ◽  
Acoustic Doppler Current Profiler ◽  
Acoustic Backscatter ◽  
Migration Behavior ◽  
Larval Instars ◽  
Reverse Migration ◽  
Coregonus Artedi ◽  
Chaoborus Punctipennis ◽  
Current Profiler

We describe a novel seasonal shift in the vertical migration behavior of Chaoborus punctipennis second-instar larvae in Lake Opeongo, Ontario. An upward-looking 600 kHz acoustic Doppler current profiler (ADCP) moored at a fixed 22 m station in the lake recorded acoustic backscatter continuously during the study period. Zooplankton samples collected indicated that the abundance of C. punctipennis larval instars accounted for the greatest proportion of variance in the linear backscatter from the ADCP. The large fourth-instar larvae underwent normal diel vertical migration throughout the study. Smaller second-instar larvae underwent reverse migration during late June but switched to normal migration by late July. The acoustic record indicates that the switch occurred over a few days around late June, and at this time a double vertical migration appeared with the second instars leading and following the migration of fourth instars. We speculate that these changes in the migration of second instars are driven by seasonal shifts in predation risk from larval cisco (Coregonus artedi) and by the need to minimize spatial overlap with the larger fourth instars.

scholarly journals Identifikasi Arus Pasang Surut di Perairan Kemujan, Karimunjawa Berdasarkan Data Pengukuran Acoustic Doppler Current Profiler

2021 ◽  
Vol 24 (2) ◽  
pp. 247-254
Author(s):  
Elis Indrayanti ◽  
Denny Nugroho Sugianto ◽  
Purwanto Purwanto ◽  
Hendry Syahputra Ropinus Siagian
Keyword(s):  
Tidal Current ◽  
Acoustic Doppler Current Profiler ◽  
Tidal Currents ◽  
Residual Current ◽  
Least Square ◽  
Ocean Currents ◽  
Velocity Data ◽  
Raw Data ◽  
Current Profiler ◽  
X 24

Ocean currents are dynamic hydro-oceanographic parameters which is play an important role in the transport of nutrients, larvae, sediment, and so on. Therefore, the identification of ocean currents including velocity, direction, sea level and the type of currents important to be studied. The research was conducted in Kemujan Water, Karimunjawa. Data for this research is based on velocity data measured using the Acoustic Doppler Current Profiler (ADCP) for 3 x 24 hours. Furthermore, the raw data of the measurement are analyzed using least square methods to obtain the characteristic of tidal current. The total current is separated into tidal currents and residual current (non-tidal currents). Result shown that the characteristic of current in Kemujan Water, Karimunjawa was tidal current. Tidal current moves bi-directional, toward the northeast and the southwest.. Arus laut merupakan parameter hidro-oseanografi yang dinamis dan mempunyai peran penting dalam transpor nutrien, larva, material, dan lain sebagainya. Oleh karena itu identifikasi arus laut meliputi kecepatan, arah, elevasi muka air laut dan tipe arus laut perlu untuk dikaji. Penelitian dilaksanakan di Perairan Kemujan  yang merupakan salah satu gugusan pulau di Karimunjawa. Data  yang dianalisa merupakan data kecepatan arus hasil pengukuran langsung menggunakan Acoustic Doppler Current Profiler (ADCP) selama 3x24 jam. Selanjutnya raw data hasil pengukuran diolah dengan metode least square untuk mengetahui karakteristik arus. Arus total dipisahkan menjadi arus pasang surut dan arus non-pasang surut (residu). Hasil penelitian menunjukkan bahwa prosentase arus pasang surut lebih besar dari arus residu, sehingga arus di Perairan Kemujan, Karimunjawa teridentifikasi sebagai arus pasang surut. Arus  bergerak secara bertolak belakang (bi-directional) yaitu pada saat surut menuju pasang arah arus menuju ke timur laut dan pada saat pasang menuju surut arah arus menuju ke barat daya.

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