scholarly journals Effectively Extracting Iceberg Freeboard Using Bi-Temporal Landsat-8 Panchromatic Image Shadows

2021 ◽  
Vol 13 (3) ◽  
pp. 430
Author(s):  
Zhenfu Guan ◽  
Xiao Cheng ◽  
Yan Liu ◽  
Teng Li ◽  
Baogang Zhang ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Global Climate ◽  
Elevation Angle ◽  
Freshwater Flux ◽  
Landsat 8 ◽  
Solar Elevation ◽  
Panchromatic Image ◽  
Aerial Vehicle ◽  
Data Gap

The freshwater flux from icebergs into the Southern Ocean plays an important role in the global climate through its impact on the deep-water formation. Large uncertainties exist in the ice volume transported by Southern Ocean icebergs due to the sparse spatial and temporal coverage of observations, especially observations of ice thickness. The iceberg freeboard is a critical geometric parameter for measuring the thickness of an iceberg and then estimating its volume. This study developed a new, highly efficient shadow-height method to precisely measure the freeboard of various icebergs surrounded by sea ice using Landsat-8 Operational Land Imager 15-m bi-temporal panchromatic image shadows at low-solar-elevation angles. We evaluated and validated shadow length precision according to bi-temporal measurements and comparison with the measurements from the unmanned aerial vehicle. We determined freeboard precision according to shadow length precision and solar elevation angle. In our case study area, 4832 available freeboard measuring points with shadow length precision better than 2 pixels covered 376 icebergs with sizes ranging from 0.002 to 0.7 km² and with freeboard ranging from 2.3 to 83.4 m. At the solar elevation angles of 5.2°, the freeboard precision of 64.1% data could reach 1 m and 86.9% could reach 2 m. Our proposed method effectively filled in the data gap of existing freeboard measurement methods.

Extracting icebergs freeboard from the shadows in Landsat-8 panchromatic images

2020 ◽  
Author(s):  
Zhenfu Guan ◽  
Yan Liu
Keyword(s):  
Large Scale ◽  
Accuracy Assessment ◽  
Elevation Angle ◽  
Absolute Error ◽  
Landsat 8 ◽  
High Precision Measurement ◽  
Solar Elevation ◽  
The Mean ◽  
The Antarctic ◽  
Solar Elevation Angle

<p><strong>Abstract:</strong> The iceberg freeboard is an important geometric parameter for measuring the thickness of the iceberg and then estimating its volume. Based on the fact that the iceberg can cast elongated shadow on the surface of sea ice in winter, this paper proposes a method to measure the iceberg freeboard using shadow length and the predefined or estimated solar elevation angle. Three Landsat-8 panchromatic images are selected to test our method, with center solar elevation angle of respectively 5.43°, 7.49°and 11.01° on August 29, September 7, and 16 September in 2016. Shadow lengths of five isolated tabular icebergs are automatically extracted to calculate the freeboard height. For the accuracy assessment, we use the matching points at the different time as cross validation. The results show that the measurement error of shadow length is less than one pixel. When the sun elevation angle is lower than 11.01°, the Root Mean Square Error (RMSE) of the iceberg freeboard from the panchromatic 15 m image is less than 2.0 m, and the Mean Absolute Error (MAE) is less than 1.5 m. Such experiment shows that: under the angle of low solar elevation in winter, the landsat-8 panchromatic 15 m image can be used for high-precision measurement of the iceberg freeboard, and has the potential to measure the Antarctic iceberg freeboard in large scale.</p><p><strong>Key </strong><strong>words:</strong> Antarctic, icebergs, freeboard, shadow altimetry, Landsat-8</p><p> </p>

Impact of LULC Changes on LST in Rajshahi District of Bangladesh: A Remote Sensing Approach

2020 ◽  
Vol 3 (1) ◽  
pp. 11-23 ◽  
Author(s):  
Abdulla Al Kafy ◽  
Abdullah Al-Faisal ◽  
Mohammad Mahmudul Hasan ◽  
Md. Soumik Sikdar ◽  
Mohammad Hasib Hasan Khan ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Surface Temperature ◽  
Land Surface ◽  
Agricultural Land ◽  
Global Climate ◽  
Urban Expansion ◽  
Water Bodies ◽  
Landsat 8 ◽  
Lulc Changes ◽  
The Impact

Urbanization has been contributing more in global climate warming, with more than 50% of the population living in cities. Rapid population growth and change in land use / land cover (LULC) are closely linked. The transformation of LULC due to rapid urban expansion significantly affects the functions of biodiversity and ecosystems, as well as local and regional climates. Improper planning and uncontrolled management of LULC changes profoundly contribute to the rise of urban land surface temperature (LST). This study evaluates the impact of LULC changes on LST for 1997, 2007 and 2017 in the Rajshahi district (Bangladesh) using multi-temporal and multi-spectral Landsat 8 OLI and Landsat 5 TM satellite data sets. The analysis of LULC changes exposed a remarkable increase in the built-up areas and a significant decrease in the vegetation and agricultural land. The built-up area was increased almost double in last 20 years in the study area. The distribution of changes in LST shows that built-up areas recorded the highest temperature followed by bare land, vegetation and agricultural land and water bodies. The LULC-LST profiles also revealed the highest temperature in built-up areas and the lowest temperature in water bodies. In the last 20 years, LST was increased about 13ºC. The study demonstrates decrease in vegetation cover and increase in non-evaporating surfaces with significantly increases the surface temperature in the study area. Remote-sensing techniques were found one of the suitable techniques for rapid analysis of urban expansions and to identify the impact of urbanization on LST.

Orchestrating the nation

2018 ◽  
Author(s):  
Barley Norton
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Global Climate ◽  
East Asian ◽  
Ancestor Worship ◽  
National Heritage ◽  
The City ◽  
Historical Periods ◽  
Party State

This chapter addresses the cultural politics, history and revival of Vietnamese court orchestras, which were first established at the beginning of the Nguyễn dynasty (1802–1945). Based on fieldwork in the city of Hue, it considers the decolonizing processes that have enabled Vietnamese court orchestras to take their place alongside other East Asian court orchestras as a display of national identity in the global community of nations. The metaphor of ‘orchestrating the nation’ is used to refer to the ways in which Vietnamese orchestras have been harnessed for sociopolitical ends in several historical periods. Court orchestras as heritage have recourse to a generic, precolonial past, yet they are not entirely uncoupled from local roots. Through a case-study of the revival of the Nam Giao Sacrifice, a ritual for ‘venerating heaven’, the chapter addresses the dynamics of interaction and exchange between staged performances of national heritage and local Buddhist and ancestor worship rituals. It argues that with growing concern about global climate change, the spiritual and ecological resonances of the Nam Giao Sacrifice have provided opportunities for the Party-state to reassert its position as the supreme guardian of the nation and its people.

scholarly journals Presenting a Semi-Automatic, Statistically-Based Approach to Assess the Sharpness Level of Optical Images from Natural Targets via the Edge Method. Case Study: The Landsat 8 OLI–L1T Data

2021 ◽  
Vol 13 (8) ◽  
pp. 1593
Author(s):  
Luca Cenci ◽  
Valerio Pampanoni ◽  
Giovanni Laneve ◽  
Carla Santella ◽  
Valentina Boccia
Keyword(s):  
Landsat 8 ◽  
Image Sharpness ◽  
Optical Images ◽  
Data Quality Assessment ◽  
Relevant Role ◽  
Edge Method ◽  
Selection Of ◽  
Statistical Criteria

Developing reliable methodologies of data quality assessment is of paramount importance for maximizing the exploitation of Earth observation (EO) products. Among the different factors influencing EO optical image quality, sharpness has a relevant role. When implementing on-orbit approaches of sharpness assessment, such as the edge method, a crucial step that strongly affects the final results is the selection of suitable edges to use for the analysis. Within this context, this paper aims at proposing a semi-automatic, statistically-based edge method (SaSbEM) that exploits edges extracted from natural targets easily and largely available on Earth: agricultural fields. For each image that is analyzed, SaSbEM detects numerous suitable edges (e.g., dozens-hundreds) characterized by specific geometrical and statistical criteria. This guarantees the repeatability and reliability of the analysis. Then, it implements a standard edge method to assess the sharpness level of each edge. Finally, it performs a statistical analysis of the results to have a robust characterization of the image sharpness level and its uncertainty. The method was validated by using Landsat 8 L1T products. Results proved that: SaSbEM is capable of performing a reliable and repeatable sharpness assessment; Landsat 8 L1T data are characterized by very good sharpness performance.

Delineation of burned arid landscapes using Landsat 8 OLI data: a case study of Karaganda region in Kazakhstan

2021 ◽  
pp. 1-16
Author(s):  
Andrey Karpachevskiy ◽  
Sergey Lednev ◽  
Ivan Semenkov ◽  
Anna Sharapova ◽  
Sultan Nagiyev ◽  
...  
Keyword(s):  
Landsat 8 ◽  
Landsat 8 Oli ◽  
Arid Landscapes ◽  
Karaganda Region

scholarly journals Disturbance, dispersal and marine assemblage structure: A case study from the nearshore Southern Ocean

2020 ◽  
Vol 160 ◽  
pp. 105025
Author(s):  
Ben J.O. Robinson ◽  
David K.A. Barnes ◽  
Simon A. Morley
Keyword(s):  
Southern Ocean ◽  
Assemblage Structure

On the Ethics of International Religious/Spiritual Gatherings and Academic Conferencing in the Era of Global Warming: A Case Study of the Parliament of The World’s Religions Melbourne 2009 - Part 1

2012 ◽  
Vol 16 (2) ◽  
pp. 179-195
Author(s):  
Almut Beringer ◽  
Steven Douglas
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Global Climate ◽  
Ghg Emissions ◽  
Ecological Impacts ◽  
Peak Oil ◽  
Ethical Challenges ◽  
Academic Events ◽  
Special Responsibility

Global climate change and its impacts have ethical dimensions, for instance carbon footprint equity concerns. World issues, including the state of the ecosphere and biodiver­sity, regularly see political leaders, NGOs, business representatives, religious/spiritual orga­nizations, academics, and others engage in international aviation-dependent meetings to address critical challenges facing humanity and the planet. Yet, climate scientists and advocates call for an 80% reduction in greenhouse gas (GHG) emissions by 2050 to cap the increase in global temperatures to 2ºC. Aviation emissions resulting from international meetings raise questions that are not silenced by GHG emissions offsetting. The era of climate change and ‘peak oil’ poses ethical challenges for holding international in-person religious and academic events, especially when the events propound an environmentalist concern and when aviation use is assumed. This paper raises ques­tions regarding the ecological impacts of large international events and focuses the ‘inconvenient truths’ associated with international aviation in the era of global warming. The Parliament of the World’s Religions, the largest multifaith gathering in the world, serves as a case study. The paper emphasizes the view that faith-based/faith-inspired organizations have a special responsibility for leadership in policy and praxis on the moral imperatives of sustainability, sustainable development and climate justice.

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