Identification of the Airspace Affected by the Presence of Volcanic Ash by Processing Satellite Images, Case Study: Popocatepétl Volcano Area

Author(s):  
José Carlos Jiménez-Escalona ◽  
Ramon S. Aparicio-García ◽  
Julie Roberge ◽  
José Eduardo Ávila-Razo ◽  
José Luis Poom-Medina ◽  
...  

Abstract A volcanic eruption can affect large areas of the atmosphere around the volcano. Commercial aviation uses these zones the airspace as a navigation zone. Encountering these ash clouds can cause severe damage to different parts of the aircraft, mainly the engines. This work aims to generate a predictive tool based on the frequency of affectation of the airspace areas around a volcano with eruptive activity, taking the Popocatépetl volcano as a case study. Was carried temporal wind analysis at different atmosphere levels to identifying direction towards which wind disperses ash in year months. This information shown two representative seasons in the direction of dispersion: the first from November to May and the second from July to September, taking into account that June and October are transitional months and therefore do not present a predominant direction. To identify the ash cloud and estimate its area, a set of MODIS images was compiled that recorded the activity in the period 2000-2014. These satellite images were subjected to a semi-automatic digital pre-processing of binarization by thresholds according to the level of the Brightness Temperature Difference between band 31 and band 32, followed by manual evaluation of each binarized image. The result of those above pre-processing was a set of pixels with spatial (longitude and latitude) and temporal (date) description, from which the history of the areas affected by ash permanence was obtained. Additionally, a set of pixels evaluated and labeled in table form could be used as training data for future artificial intelligence applications to automatically detect and discriminate ash clouds.

Lithos ◽  
2021 ◽  
pp. 106540
Author(s):  
Simone Tommasini ◽  
Luca Bindi ◽  
Lorenzo Savia ◽  
Martin F. Mangler ◽  
Andrea Orlando ◽  
...  

2008 ◽  
Vol 170 (1-2) ◽  
pp. 99-110 ◽  
Author(s):  
C. Huggel ◽  
D. Schneider ◽  
P. Julio Miranda ◽  
H. Delgado Granados ◽  
A. Kääb

Author(s):  
Odile Moreau

This chapter explores movement and circulation across the Mediterranean and seeks to contribute to a history of proto-nationalism in the Maghrib and the Middle East at a particular moment prior to World War I. The discussion is particularly concerned with the interface of two Mediterranean spaces: the Middle East (Egypt, Ottoman Empire) and North Africa (Morocco), where the latter is viewed as a case study where resistance movements sought external allies as a way of compensating for their internal weakness. Applying methods developed by Subaltern Studies, and linking macro-historical approaches, namely of a translocal movement in the Muslim Mediterranean, it explores how the Egypt-based society, al-Ittihad al-Maghribi, through its agent, Aref Taher, used the press as an instrument for political propaganda, promoting its Pan-Islamic programme and its goal of uniting North Africa.


2010 ◽  
Vol 1 (1) ◽  
pp. 75-93
Author(s):  
Jessica Moberg

Immediately after the Second World War Sweden was struck by a wave of sightings of strange flying objects. In some cases these mass sightings resulted in panic, particularly after authorities failed to identify them. Decades later, these phenomena were interpreted by two members of the Swedish UFO movement, Erland Sandqvist and Gösta Rehn, as alien spaceships, or UFOs. Rehn argued that ‘[t]here is nothing so dramatic in the Swedish history of UFOs as this invasion of alien fly-things’ (Rehn 1969: 50). In this article the interpretation of such sightings proposed by these authors, namely that we are visited by extraterrestrials from outer space, is approached from the perspective of myth theory. According to this mythical theme, not only are we are not alone in the universe, but also the history of humankind has been shaped by encounters with more highly-evolved alien beings. In their modern day form, these kinds of ideas about aliens and UFOs originated in the United States. The reasoning of Sandqvist and Rehn exemplifies the localization process that took place as members of the Swedish UFO movement began to produce their own narratives about aliens and UFOs. The question I will address is: in what ways do these stories change in new contexts? Texts produced by the Swedish UFO movement are analyzed as a case study of this process.


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