ORCID Profile
0000-0001-6832-8289
Current Organisation
CSIRO
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 10-2012
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2016
Publisher: Informa UK Limited
Date: 10-05-2014
Publisher: AIP
Date: 2012
DOI: 10.1063/1.4765921
Publisher: CSIRO. Marine and Atmospheric Research
Date: 2017
Publisher: ICES
Date: 2019
Publisher: Elsevier BV
Date: 10-2023
Publisher: Copernicus GmbH
Date: 10-01-2014
Abstract: Abstract. Dual-frequency echo-envelope data acquired using the normal-incidence single-beam echosounder system (SBES) have been examined to study its scale invariant properties. The scaling and multifractality of the SBES echo envelopes (at 33 and 210 kHz) were validated by applying a stochastic-based multifractal analysis technique. The analyses carried out substantiate the hierarchy of multiplicative cascade dynamics in the echo envelopes, demonstrating a first-order multifractal phase transition. The resulting scale invariant parameters (α, C1, and H) establish gainful information that can facilitate distinctive delineation of the sediment provinces in the central part of the western continental shelf of India. The universal multifractal parameters among the coarse and fine sediments exhibit subtle difference in α and H, whereas the codimension parameter C1 representing the sparseness of the data varies. The C1 values are well clustered at both the acoustic frequencies, demarcating the coarse and fine sediment provinces. Statistically significant correlations are noticeable between the computed C1 values and the ground truth sediment information. The variations in the multifractal parameters and their behavior with respect to the ground truth sediment information are in good corroboration with the previously estimated sediment geoacoustic inversion results obtained at the same locations.
Publisher: IEEE
Date: 02-2015
Publisher: Springer Science and Business Media LLC
Date: 19-02-2014
Publisher: Australian Ocean Data Network
Date: 2022
DOI: 10.26198/Q7MP-GX77
Publisher: Oxford University Press (OUP)
Date: 02-12-2018
Abstract: Acoustic quantification of aquatic biomass using echosounders requires accurate calibration. With the advancing applications of deep-water echosounders involving moored, towed, profiling and autonomous instruments, calibration of echosounders at the operating depth is needed to ensure unbiased estimates of biomass and species identification. In this context, the deepwater calibration acoustic facility (DeCAF) was used to examine the depth-dependent variations in on-axis gain (G0) and equivalent two-way beam angle (Ψ) of three different transducers, operating at 38 (Simrad ES38-DD and MSI-38) and 120 kHz (Simrad ES120-7CD) used for biomass surveys and species identification. The analyses carried out using the sphere calibration method reveal significant variations in calibrated G0 and Ψ that in combination could result in substantial systemic biases in quantitative biomass estimation and species identification. The depth-dependent G0 variations derived using the DeCAF system are in accordance with available deep-water calibration results, demonstrating reasonable repeatability of target strength measurements (±0.6 dB) over the calibration deployments. Importantly, Ψ of the transducers was calculated to be consistently lower than the values specified by the manufacturer, and for one transducer would result in 18% change in the estimated biomass. These results highlight the potential for bias if the Ψ of transducer is not independently calculated using the actual survey echosounder.
Publisher: ICES
Date: 2021
Publisher: Acoustical Society of America (ASA)
Date: 12-2011
DOI: 10.1121/1.3658454
Abstract: Sediment geoacoustic inversion results are estimated employing a multi-beam (MB) echo-sounding system operable at 95 kHz. To characterize the western continental shelf of India (off Goa) seafloor, MB backscatter signals were acquired along with grab sediment s les. The substrate type and roughness of the site were estimated using the composite roughness scattering model with the measured backscatter values. The seafloor parameters, namely mean grain size (Mϕ) roughness spectrum strength (w2) and exponent (γ2) and sediment volume parameter (σ2), for coarse and fine grain sediments are estimated by employing the MB system. These parameters have also been estimated at two other frequencies (33 and 210 kHz) and are compared to the ground truth data to provide sufficient support in validating the model results and increasing the understanding of the shelf seafloor processes. Distinct interclass separations between the sediment provinces are evident from the estimated mean grain size Mϕ and water-sediment interface roughness w2. The seafloor parameters for coarse and fine grain sediments derived from the 95 kHz MB data are consistent with the sediment s le data as well as with the inversion results obtained using backscatter data at 33 and 210 kHz from the same locations.
Publisher: Springer Science and Business Media LLC
Date: 20-01-2021
DOI: 10.1038/S41597-020-00785-8
Abstract: Shedding light on the distribution and ecosystem function of mesopelagic communities in the twilight zone (~200–1000 m depth) of global oceans can bridge the gap in estimates of species biomass, trophic linkages, and carbon sequestration role. Ocean basin-scale bioacoustic data from ships of opportunity programs are increasingly improving this situation by providing spatio-temporal calibrated acoustic snapshots of mesopelagic communities that can mutually complement established global ecosystem, carbon, and biogeochemical models. This data descriptor provides an overview of such bioacoustic data from Australia’s Integrated Marine Observing System (IMOS) Ships of Opportunity (SOOP) Bioacoustics sub-Facility. Until 30 September 2020, more than 600,000 km of data from 22 platforms were processed and made available to a publicly accessible Australian Ocean Data Network (AODN) Portal. Approximately 67% of total data holdings were collected by 13 commercial fishing vessels, fostering collaborations between researchers and ocean industry. IMOS Bioacoustics sub-Facility offers the prospect of acquiring new data, improved insights, and delving into new research challenges for investigating status and trend of mesopelagic ecosystems.
Publisher: CSIRO
Date: 2018
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2014
Publisher: Acoustical Society of America (ASA)
Date: 10-2014
DOI: 10.1121/1.4895713
Abstract: Nonlinear phenomena in animal vocalizations fundamentally includes known features, namely, frequency jump, subharmonics, biphonation, and deterministic chaos. In the present study, the multifractal detrended fluctuation analysis (MFDFA) has been employed to characterize the phase couplings revealed in the feeding clicks of Hippoc us kuda yellow seahorse. The fluctuation function Fq(s), generalized Hurst exponent h(q), multifractal scaling exponent τ(q), and the multifractal spectrum f(α) calculated in the procedure followed were analyzed to comprehend the underlying nonlinearities in the seahorse clicks. The analyses carried out reveal long-range power-law correlation properties in the data, substantiating the multifractal behavior. The resulting h(q) spectrum exhibits a distinct characteristic pattern in relation to the seahorse sex and size, and reveals a spectral blind spot in the data that was not possible to detect by conventional spectral analyses. The corresponding multifractal spectrum related width parameter Δh(q) is well clustered, defining the in idual seahorse clicks. The highest degree of multifractality is evident in the 18 cm male seahorse, signifying greater heterogeneity. A further comparison between the seahorse body size and weight (wet) with respect to the width parameter Δh(q) and the second-order Hurst exponent h(q=2) underscores the versatility of MFDFA as a robust statistical tool to analyze bioacoustic observations.
Location: Australia
No related grants have been discovered for Haris Kunnath.