Samy Djavidnia - Academia.edu (original) (raw)

Papers by Samy Djavidnia

Proceedings of Meetings on Acoustics

Continuous underwater noise from shipping has been identified as one of the main contributors to ... more Continuous underwater noise from shipping has been identified as one of the main contributors to ambient noise levels in the oceans. Notwithstanding the potential impacts on marine life, the subject started receiving attention from international and regional regulatory bodies only very recently. Last year, the European Maritime Safety Agency commissioned a study to consolidate information about continuous underwater noise from shipping in order to derive recommendations for a future multi-stakeholder strategy within Europe. The work reviewed information about sources of continuous noise, environmental impacts, the policies in place to manage underwater noise and available mitigation measures to reduce noise levels. Effective management of underwater noise from ships is a multi-sectoral challenge requiring coordination between different policies and stakeholders. Based on an online survey and a number of interviews, it was possible to elucidate: 1) how different stakeholders interact; 2) the main drivers for addressing underwater noise; and 3) possible strategies for tackling the subject effectively. Additionally, considerations and lessons learned from ECHO program in Canada were analysed as a case study. The paper will describe the main activities carried out in the project, focusing on recommendations for effective mitigation of ship noise.

$Research paper thumbnail of An Introduction to the \u27Oceans and Society: Blue Planet\u27 Initiative$

We live on a blue planet, and Earth’s waters benefit many sectors of society. The future of our b... more We live on a blue planet, and Earth’s waters benefit many sectors of society. The future of our blue planet is increasingly reliant on the services delivered by marine, coastal and inland waters and on the advancement of effective, evidence-based decisions on sustainable development. ‘Oceans and Society: Blue Planet’ is an initiative of the Group on Earth Observations (GEO) that aims to ensure the sustained development and use of ocean and coastal observations for the benefit of society. The initiative works to advance and exploit synergies among the many observational programmes devoted to ocean and coastal waters; to improve engagement with a variety of stakeholders for enhancing the timeliness, quality and range of information delivered; and to raise awareness of the societal benefits of ocean observations at the public and policy levels. This paper summarises the role of the initiative, current activities and considerations for future directions

Marine Policy, 2021

Marine biodiversity is a fundamental characteristic of our planet that depends on and influences ... more Marine biodiversity is a fundamental characteristic of our planet that depends on and influences climate, water quality, and many ocean state variables. It is also at the core of ecosystem services that can make or break economic development in any region. Our purpose is to highlight the need for marine biological observations to inform science and conservation management and to support the blue economy. We provide ten recommendations, applicable now, to measure and forecast biological Essential Ocean Variables (EOVs) as part of economic monitoring efforts. The UN Decade of Ocean Science for Sustainable Development (2021-2030) provides a timely opportunity to implement these recommendations to benefit humanity and enable the USD 3 trillion global ocean economy expected by 2030.

Frontiers in Marine Science, 2019

The importance of stakeholder engagement in ocean observation and in particular the realization o... more The importance of stakeholder engagement in ocean observation and in particular the realization of economic and societal benefits is discussed, introducing a number of overarching principles such as the convergence on common goals, effective communication, co-production of information and knowledge and the need for innovation. A series of case studies examine the role of coordinating frameworks such as the United States' Interagency Ocean Observing System (IOOS R), and the European Ocean Observing System (EOOS), public-private partnerships such as Project Azul and the Coastal Data Information Program (CDIP) and finally the role of the "third" or voluntary sector. The paper explores the value that stakeholder engagement can bring as well as making recommendations for the future.

Journal of Operational Oceanography, 2019

We live on a blue planet, and Earth's waters benefit many sectors of society. The future of our b... more We live on a blue planet, and Earth's waters benefit many sectors of society. The future of our blue planet is increasingly reliant on the services delivered by marine, coastal and inland waters and on the advancement of effective, evidence-based decisions on sustainable development. 'Oceans and Society: Blue Planet' is an initiative of the Group on Earth Observations (GEO) that aims to ensure the sustained development and use of ocean and coastal observations for the benefit of society. The initiative works to advance and exploit synergies among the many observational programmes devoted to ocean and coastal waters; to improve engagement with a variety of stakeholders for enhancing the timeliness, quality and range of information delivered; and to raise awareness of the societal benefits of ocean observations at the public and policy levels. This paper summarises the role of the initiative, current activities and considerations for future directions.

Journal of Operational Oceanography, 2018

Disclaimer Informa UK Limited, trading as Taylor & Francis Group, make every effort to ensure the... more Disclaimer Informa UK Limited, trading as Taylor & Francis Group, make every effort to ensure the accuracy of all the information (the "Content") contained in our publications. However, Informa UK Limited, trading as Taylor & Francis Group, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Informa UK Limited, trading as Taylor & Francis Group. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Informa UK Limited, trading as Taylor & Francis Group, shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content.

Space Sciences Series of ISSI, 2000

The response of the lower and middle atmosphere to variations in solar irradiance typical of thos... more The response of the lower and middle atmosphere to variations in solar irradiance typical of those observed to take place over the 11-year activity cycle has been investigated. The effects on radiative heating rates of changing total solar irradiance, solar spectral irradiance and two different assumptions concerning stratospheric ozone have been studied with a radiative transfer code. The response in the stratosphere depends on the changes specified in the ozone distribution which is not well known. A general circulation model (GCM) of the atmosphere up to 0.1 mbar (about 65 km) has been used to study the impacts of these changes on the thermodynamical structure. The results in the troposphere are very similar to those reported by Haigh (1999) using a quite different GCM. In the middle atmosphere the model is able to reproduce quite well the observed seasonal evolution of temperature and wind anomalies. Calculations of radiative forcing due to solar variation are presented. These show that the thermal infrared component of the forcing, due to warming of the stratosphere, is important but suggest a near balance between the longwave and shortwave effects of the increased ozone so that ozone change may not be important for net radiative forcing. However, the structure of the ozone change does affect the detailed temperature response and the spectral composition of the radiation entering the troposphere.

ABSTRACT In this paper, an associative mapping data fusion approach to operational oil spill dete... more ABSTRACT In this paper, an associative mapping data fusion approach to operational oil spill detection is investigated focusing on the combination of Synthetic Aperture Radar (SAR) imagery derived data, and ancillary information such as metocean and contextual data. The ancillary data related to the investigated area are processed together with the features of the detected dark objects extracted from the SAR image using Artificial Neural Networks, ultimately leading to the estimation of a reliability index of the oil spill detection. The detection reliability measure can be thought of as the likelihood of the object being an oil spill given the SAR, context and metocean available information.

The accreting millisecond pulsar XTE J1807-294, discovered by RXTE on February 21, 2003 \citep{ma... more The accreting millisecond pulsar XTE J1807-294, discovered by RXTE on February 21, 2003 \citep{markwardt_8080}, was observed as Target of Opportunity (ToO) by XMM-Newton on March 22, 2003. The source was detected in bright phase with an observed count rate of 33.3 cts s-1 in the EPIC pn-CCD camera in the 0.5-10 keV band (3.7 mCrab). Using the best-fit orbital period of 40.0741±0.0005 minutes reported by \citep{markwardt_127} and assuming a circular orbit as first approximation, we derived 4.8±0.1 light-ms for the projected orbital radius. The barycentric mean spin-period of the pulsar was derived as 5.2459427±0.0000004 ms. The modulation is seen over the entire energy band from 0.5 to 10 keV. The combined pulse profile in the 0.5-10 keV band shows a modulation of 6.0±0.1 % (90 % confidence).

IEEE Geoscience and Remote Sensing Letters, 2012

ABSTRACT With its two daily acquisitions and the possibility to obtain near-real-time data free o... more ABSTRACT With its two daily acquisitions and the possibility to obtain near-real-time data free of charge, the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) shows interesting potential as a cost-effective supplementary tool for oil spill monitoring in the marine environment. The mechanism behind MODIS oil feature detection, as well as the type of information that might be retrieved, strictly depends on the illumination conditions. In the presence of sunglint contamination, MODIS can just locate the oil spill as a sea surface roughness anomaly, in similarity with radar observations, and no additional spectral information can be retrieved. MODIS detection in the absence of sunglint contamination however might allow extraction of oil feature spectral properties, which, in turn, may help in oil discrimination and classification. Careful atmospheric correction must be applied. An example of oil spill spectral property extraction from MODIS images is here shown for the Deepwater Horizon accidental oil spill.

Astronomy & Astrophysics, 2004

The accreting millisecond pulsar XTE J1807−294 was observed as a Target of Opportunity (ToO) by X... more The accreting millisecond pulsar XTE J1807−294 was observed as a Target of Opportunity (ToO) by XMM-Newton on March 22, 2003 after its discovery on February 21, 2003 by RXTE. The source was detected in its bright phase with an observed average count rate of 33.3 cts s −1 in the EPIC-pn camera in the 0.5-10 keV energy band (3.7 mCrab). Using the earlier established best-fit orbital period of 40.0741 ± 0.0005 min from the RXTE observations and considering a circular binary orbit as first approximation, we derived a value of 4.8 ± 0.1 lt-ms for the projected orbital radius of the binary system and an epoch of the orbital phase of MJD 52 720.67415(16). The barycentric mean spin period of the pulsar was derived as 5.2459427 ± 0.0000004 ms. The pulsar's spin-pulse profile showed a prominent (1.5 ms FWHM) pulse, with energy and orbital phase dependence in the amplitude and shape. The measured pulsed fraction in four energy bands was found to be 3.1 ± 0.2%