Improved SAR Altimetry Techniques in Coastal Island Areas

<p>Improved SAR Altimetry Techniques in Coastal Island Areas</p><p>Synthetic Aperture Radar (SAR) Altimetry has made a remarkable progress over the past years. Advances in data processing, combined with technological progress such as the advent of new Altimetry satellites (Sentinel 3A,3B,6, SWOT etc.) increased the accuracy of the retrieved geophysical parameters (i.e., Sea Level Anomaly, Significant Wave Height and Wind Speed) in coastal zones within several hundred meters from the coastline.</p><p>The improvement in the estimation of the geophysical parameters using SAR Altimetry has been reported by many researchers. The improved accuracy is obtained through the development of new SAR Altimetry retracking algorithms in several research and development projects (i.e., SAR Altimetry Mode Studies and Applications-SAMOSA).  Similar to Low Resolution Mode (LRM) Altimetry, the requirement of specialized retrackers for SAR waveforms is vital in improving the estimated ocean parameters. The waveform retracking is a postprocessing protocol to convert waveforms into scientific parameters of power amplitude (related to wind speed), range (related to sea level), and slope of leading edge (related to SWH) that characterize the observed scene (Idris et al., 2021).</p><p>However, several issues remain open. Close to the coastline, SAR altimeter simultaneously views scattering surfaces of both water and land producing complicated waveform patterns therefore a huge range of waveform shapes is observed. This complexity poses a real challenge to today’s approach to retrack waveform.</p><p>The combination of different retracking algorithms is essential for dealing with this high diversity of altimetric waveform patterns since there is no single retracker that can retrack all of them. However, this raises two significant issues. The first is regarding to the selection of the optimal retracker under various conditions. The lack of a clear guideline on the selection criteria of the optimal retracker limits the use of this combining method. The second is how to reduce the offset caused by switching retrackers, as it results in relative offsets in altimeter-derived SLAs. This offset is partly caused by the retracking method itself, in which the fitting algorithms are affected by noise in the trailing edge due to the SWHs variability (Idris et al., 2018).</p><p>Due to the issues in coastal Altimetry data the focus of this work is:</p><ul><li>1) To improve the sea measurements from the SAR Altimetry missions by developing a new retracking algorithm taking advantage artificial intelligence and machine learning technologies.</li> </ul><p> </p><ul><li>2) To further investigate the assessment of the offset between various retrackers and the use of a neural network for reducing the offset in the retracked SLAs by including information about SWH.</li> </ul><p> </p><ul><li>3) To validate the altimeter derived SLAs by performing tests and comparisons with data from many island coastal areas worldwide.</li> </ul><p>Also, this work aims to improve the Sea State Bias corrections (SSB), which is currently one of the range corrections with the largest uncertainty in the coastal zone (Vignudelli et al., 2019), by providing more accurate sea measurements near the coast.</p>

A spatial reference and identification system for coastal ice-free land in East Antarctica

We describe a spatial reference system that uniquely identifies 4884 coastal island and continental rock features across East Antarctica. The system comprises a series of maps and a related database, and can be a foundation tool for a wide range of environmental studies.

Trypanosoma cruzi-infected triatomines and rodents co-occur in a coastal island of northern Chile

Trypanosoma cruzi, the cause agent of Chagas disease, is transmitted mainly by blood-feeding insects of the subfamily Triatominae. The T. cruzi life cycle alternates between triatomines and mammalian hosts, excluding birds and reptiles. Triatomines of Mepraia genus are wild vectors of T. cruzi in Chile. Mepraia specimens infected with T. cruzi have been detected in Pan de Azúcar and Santa María islands. The most common vertebrates that inhabit these islands are birds and reptiles, and it is unknown whether small mammals are present. Consequently, it is relevant to know whether there are any T. cruzi-infected small mammals on those islands to elucidate the T. cruzi cycle. To clarify this crossroads, islands of northern Chile were explored to determine if T. cruzi-infected triatomines and rodents co-occur in islands of northern Chile. T. cruzi DNA was detected by conventional and real-time PCR in three islands: on Santa María and Pan de Azúcar islands T. cruzi was detected in Mepraia sp samples, while on Pan de Azúcar (6.1%) and Damas islands (15%) was detected in the rodent Abrothrix olivacea. We show for the first time in Chile the occurrence of insular rodents infected with T. cruzi, and a complete T. cruzi life cycle in a coastal island. Our results provide new insights to understand the T. cruzi infection in the wild cycle.

An Economic and sustainable planning of Bhasan Char as an Exclusive tourism spot with off-grid SMART Green Energy System

Bhasan char is a coastal island at Hatiya Upzilla of Noakhali District. It is a single char which has been uncovered from the Bay of Bengal a few years back. An emergency humanitarian project implemented by the Bangladesh government at this coastal island “Bhasan Char”, from September 2017, to temporarily rehabilitate a portion of incoming Rohingya refugees before they can repatriate to their homeland, Myanmar. Under this project, Government of Bangladesh (GoB) carried out land development, construction of embankment as well as other infrastructures. Upon repatriation of Rohingya's to Myanmar, we can use the developed land & surroundings as exclusive tourist zone. This paper is an outline to establish Bhasan Char as an exclusive tourist spot and a feasibility analysis of an off-grid hybrid energy generation system for this proposed tourism spot. Here, we had conducted a hypothetical zonal design, energy estimation, off-grid energy distribution, energy generation and a sustainable tariff plan for this exclusive zone in modular basis.