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A model-based temperature adjustment scheme for wintertime sea-ice production retrievals from MODIS
Get PDFKnowledge of the wintertime sea-ice production in Arctic polynyas is an important requirement for estimations of the dense water formation, which drives vertical mixing in the upper ocean. Satellite-based techniques incorporating relatively high resolution thermal-infrared data from MODIS in combination with atmospheric reanalysis data have proven to be a strong tool to monitor large and regularly forming polynyas and to resolve narrow thin-ice areas (i.e., leads) along the shelf-breaks and across the entire Arctic Ocean. However, the selection of the atmospheric data sets has a large influence on derived polynya characteristics due to their impact on the calculation of the heat loss to the atmosphere, which is determined by the local thin-ice thickness. In order to overcome this methodical ambiguity, we present a MODIS-assisted temperature adjustment (MATA) algorithm that yields corrections of the 2 m air temperature and hence decreases differences between the atmospheric input data sets. The adjustment algorithm is based on atmospheric model simulations. We focus on the Laptev Sea region for detailed case studies on the developed algorithm and present time series of polynya characteristics in the winter season 2019/2020. It shows that the application of the empirically derived correction decreases the difference between different utilized atmospheric products significantly from 49% to 23%. Additional filter strategies are applied that aim at increasing the capability to include leads in the quasi-daily and persistence-filtered thin-ice thickness composites. More generally, the winter of 2019/2020 features high polynya activity in the eastern Arctic and less activity in the Canadian Arctic Archipelago, presumably as a result of the particularly strong polar vortex in early 2020
Detection of Individual Tree Stems Using ALS and its Potential for Forest Research
Get PDFForest inventories provide significant monitoring information on forest health, biodiversity,
resilience against disturbance, as well as its biomass and timber harvesting potential. For this
purpose, modern inventories increasingly exploit the advantages of airborne laser scanning (ALS)
and terrestrial laser scanning (TLS).
Although tree crown detection and delineation using ALS can be seen as a mature discipline, the
identification of individual stems is a rarely addressed task. In particular, the informative value of
the stem attributes—especially the inclination characteristics—is hardly known. In addition, a lack
of tools for the processing and fusion of forest-related data sources can be identified. The given
thesis addresses these research gaps in four peer-reviewed papers, while a focus is set on the
suitability of ALS data for the detection and analysis of tree stems.
In addition to providing a novel post-processing strategy for geo-referencing forest inventory plots,
the thesis could show that ALS-based stem detections are very reliable and their positions are
accurate. In particular, the stems have shown to be suited to study prevailing trunk inclination
angles and orientations, while a species-specific down-slope inclination of the tree stems and a
leeward orientation of conifers could be observed.Waldinventuren stellen für Wälder grundlegende Informationen zum Gesundheitszustand, der
Biodiversität
und
Widerstandsfähigkeit,
sowie
zur
Biomasse
und
dem
potentiellen
Holzerntevolumen bereit. Zu diesem Zweck werden in modernen Inventuren zunehmend die
Vorteile von luftgestütztem (ALS) und terrestrischem Laserscanning (TLS) genutzt.
Obwohl die Detektion und Segmentierung einzelner Baumkronen basierend auf ALS als
ausgereifte Wissenschaft ansgesehen werden kann, wird nur selten versucht einzelne
Baumstämme zu identifizieren. Über den Informationsgehalt der Stammattribute – vor allem der
Neigungseigenschaften – ist nur wenig bekannt. Unabhängig davon ist auch ein Mangel an
Software für die Verarbeitung und Fusion von Forstdaten festzustellen. Die vorliegende Arbeit geht
auf diese Defizite in vier Forschungsartikeln ein, wobei ein Schwerpunkt auf die Eignung von ALS
für die Detektion und Auswertung von Stämmen gelegt wird.
Neben der Vorstellung einer neuartigen Strategie zur Georeferenzierung von Waldinventurdaten
konnte die Arbeit zeigen, dass mit ALS Stämme zuverlässig und positionsgenau detektiert werden
können. Insbesondere konnten präferierte Stammneigungen, wie eine baumartenabhängige
Hangabwärtsneigung oder eine Neigung von Nadelbäumen in Windrichtung, beobachtet werden
Les mini-entreprises
Get PDFLes entreprises d’élèves, ci-après désignées mini-entreprises, ne présentent pas seulement des occasions de développer des compétences économiques dans un contexte réel orienté vers l’action, mais aussi une possibilité pour les élèves de s’engager en dehors de l’école à travers des offres au sein de la communauté et de la société
La coopération scolaire transnationale comme opportunité d’apprentissage interculturel
Get PDFLes projets scolaires transnationaux offrent de multiples opportunités d’ouverture des écoles et de rencontres interculturelles. La Grande Région en particulier, avec ses références et ses dynamiques transnationales, peut être utilisée comme lieu d’échange culturel et d’intégration européenne « à portée de main »
L’engagement bénévole individuel sur le terrain comme opportunité d’apprentissage
Get PDFL’engagement bénévole – que ce soit au sein de clubs sportifs ou en politique, chez les pompiers ou dans l’aide à l’intégration – est d’une grande valeur pour la cohésion sociale. Les élèves peuvent en outre y faire de précieuses expériences en matière d’éducation à la démocratie, se consacrer à des thèmes extracurriculaires et offrirà leur école des possibilités d’ouverture et de coopération
Ouvrir l’école : Inviter des responsables politiques et des initiatives sociopolitiques
Get PDFLorsqu’il s’agit d’inviter des personnalités issues du monde politique et social à l’école, les enseignant·e·s se posent généralement beaucoup de questions. En ce qui concerne les responsables politiques en particulier, cela en chagrine même plus d’un·e. Comment s’assurer que l’échange est profitable pour toutes les parties
How to choose the size of facial areas of interest in interactive eye tracking
Get PDFAdvances in eye tracking technology have enabled the development of interactive experimental setups to study social attention. Since these setups differ substantially from the eye tracker manufacturer’s test conditions, validation is essential with regard to the quality of gaze data and other factors potentially threatening the validity of this signal. In this study, we evaluated the impact of accuracy and areas of interest (AOIs) size on the classification of simulated gaze (fixation) data. We defined AOIs of different sizes using the Limited-Radius Voronoi-Tessellation (LRVT) method, and simulated gaze data for facial target points with varying accuracy. As hypothesized, we found that accuracy and AOI size had strong effects on gaze classification. In addition, these effects were not independent and differed in falsely classified gaze inside AOIs (Type I errors; false alarms) and falsely classified gaze outside the predefined AOIs (Type II errors; misses). Our results indicate that smaller AOIs generally minimize false classifications as long as accuracy is good enough. For studies with lower accuracy, Type II errors can still be compensated to some extent by using larger AOIs, but at the cost of more probable Type I errors. Proper estimation of accuracy is therefore essential for making informed decisions regarding the size of AOIs in eye tracking research
How experience with tone in the native language affects the L2 acquisition of pitch accents
Get PDFThis paper tested the ability of Mandarin learners of German, whose native language has lexical tone, to imitate pitch accent contrasts in German, an intonation language. In intonation languages, pitch accents do not convey lexical information; also, pitch accents are sparser than lexical tones as they only associate with prominent words in the utterance. We compared two kinds of German pitch-accent contrasts: (1) a “non-merger” contrast, which Mandarin listeners perceive as different and (2) a “merger” contrast, which sounds more similar to Mandarin listeners. Speakers of a tone language are generally very sensitive to pitch. Hypothesis 1 (H1) therefore stated that Mandarin learners produce the two kinds of contrasts similarly to native German speakers. However, the documented sensitivity to tonal contrasts, at the expense of processing phrase-level intonational contrasts, may generally hinder target-like production of intonational pitch accents in the L2 (Hypothesis 2, H2). Finally, cross-linguistic influence (CLI) predicts a difference in the realization of these two contrasts as well as improvement with higher proficiency (Hypothesis 3, H3). We used a delayed imitation paradigm, which is well-suited for assessing L2-phonetics and -phonology because it does not necessitate access to intonational meaning. We investigated the imitation of three kinds of accents, which were associated with the sentence-final noun in short wh-questions (e.g., Wer malt denn Mandalas, lit: “Who draws PRT mandalas?” “Who likes drawing mandalas?”). In Experiment 1, 28 native speakers of Mandarin participated (14 low- and 14 high-proficient). The learners’ productions of the two kinds of contrasts were analyzed using General Additive Mixed Models to evaluate differences in pitch accent contrasts over time, in comparison to the productions of native German participants from an earlier study in our lab. Results showed a more pronounced realization of the non-merger contrast compared to German natives and a less distinct realization of the merger contrast, with beneficial effects of proficiency, lending support to H3. Experiment 2 tested low-proficient Italian learners of German (whose L1 is an intonation language) to contextualize the Mandarin data and further investigate CLI. Italian learners realized the non-merger contrast more target-like than Mandarin learners, lending additional support to CLI (H3)
Monitoring dryland trees with remote sensing. Part B: Combining tree cover and plant architecture data to assess degradation and recovery of Argania spinosa woodlands of South Morocco
Get PDFThe argan woodlands of South Morocco represent an open-canopy dryland forest with traditional silvopastoral usage that includes browsing by goats, sheep and camels, oil production as well as agricultural use. In the past, these forests have undergone extensive clearing, but are now protected by the state. However, the remaining argan woodlands are still under pressure from intensive grazing and illegal firewood collection. Although the argan-forest area seems to be overall decreasing due to large forest clearings for intensive agriculture, little quantitative data is available on the dynamics and overall state of the remaining argan forest. To determine how the argan woodlands in the High Atlas and the Anti-Atlas had changed in tree-crown cover from 1972 to 2018 we used historical black and white HEXAGON satellite images as well as recent WorldView satellite images (see Part A of our study). Because tree shadows can oftentimes not be separated from the tree crown on panchromatic satellite images, individual trees were mapped in three size categories to determine if trees were unchanged, had decreased/increased in crown size or had disappeared or newly grown. The current state of the argan trees was evaluated by mapping tree architectures in the field. Tree-cover changes varied highly between the test sites. Trees that remained unchanged between 1972 and 2018 were in the majority, while tree mortality and tree establishment were nearly even. Small unchanged trees made up 48.4% of all remaining trees, of these 51% showed degraded tree architectures. 40% of small (re-) grown trees were so overbrowsed that they only appeared as bushes, while medium (3–7 m crown diameter) and large trees (>7 m) showed less degraded trees regardless if they had changed or not. Approaches like grazing exclusion or cereal cultivation lead to a positive influence on tree architecture and less tree-cover decrease. Although the woodland was found to be mostly unchanged 1972–2018, the analysis of tree architecture reveals that a lot of (mostly small) trees remained stable but in a degraded state. This stability might be the result of the small trees’ high degradation status and shows the heavy pressure on the argan forest
Lernen durch Engagement à l’Atert-Lycée Réiden : Ouvrir l’école et favoriser l’engagement social en classe
Get PDFDepuis quelques années, des projets sont menés à l’Atert Lycée Réiden selon la méthode Lernen durch Engagement (LdE). La communauté scolaire et son environnement social profitent de cette ouverture de l’école et de l’enseignement ainsi que de la promotion de l’engagement social dans la classe