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Characteristics of taiga and tundra snowpack in development and validation of remote sensing of snow / Henna-Reetta Hannula (2022)  

Public Titre : Characteristics of taiga and tundra snowpack in development and validation of remote sensing of snow Type de document : Thèse/HDR Auteurs : Henna-Reetta Hannula, Auteur Editeur : Helsinki [Finland] : University of Helsinki Année de publication : 2022 Importance : 79 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-952-336-153-9 Note générale : Bibliographie Academic dissertation, Faculty of Science, University of Helsinki Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] analyse des mélanges spectraux [Termes IGN] carte thématique [Termes IGN] changement climatique [Termes IGN] distribution du coefficient de réflexion bidirectionnelle BRDF [Termes IGN] distribution spatiale [Termes IGN] données spatiotemporelles [Termes IGN] échantillonnage de données [Termes IGN] Finlande [Termes IGN] forêt boréale [Termes IGN] image infrarouge [Termes IGN] manteau neigeux [Termes IGN] problème inverse [Termes IGN] réflectance spectrale [Termes IGN] taïga [Termes IGN] toundra Résumé : (auteur) Remote sensing of snow is a method to measure snow cover characteristics without direct physical contact with the target from airborne or space-borne platforms. Reliable estimates of snow cover extent and snow properties are vital for several applications including climate change research and weather and hydrological forecasting. Optical remote sensing methods detect the extent of snow cover based on its high reflectivity compared to other natural surfaces. A universal challenge for snow cover mapping is the high spatiotemporal variability of snow properties and heterogeneous landscapes such as the boreal forest biome. The optical satellite sensor’s footprint may extend from tens of meters to a kilometer; the signal measured by the sensor can simultaneously emerge from several target categories within individual satellite pixels. By use of spectral unmixing or inverse model-based methods, the fractional snow cover (FSC) within the satellite image pixel can be resolved from the recorded electromagnetic signal. However, these algorithms require knowledge of the spectral reflectance properties of the targets present within the satellite scene and the accuracy of snow cover maps is dependent on the feasibility of these spectral model parameters. On the other hand, abrupt changes in land cover types with large differences in their snow properties may be located within a single satellite image pixel and complicate the interpretation of the observations. Ground-based in-situ observations can be used to validate the snow parameters derived by indirect methods, but these data are affected by the chosen sampling. This doctoral thesis analyses laboratory-based spectral reflectance information on several boreal snow types for the purpose of the more accurate reflectance representation of snow in mapping method used for the detection of fractional snow cover. Multi-scale reflectance observations representing boreal spectral endmembers typically used in optical mapping of snow cover, are exploited in the thesis. In addition, to support the interpretation of remote sensing observations in boreal and tundra environments, extensive in-situ dataset of snow depth, snow water equivalent and snow density are exploited to characterize the snow variability and to assess the uncertainty and representativeness of these point-wise snow measurements applied for the validation of remote sensing observations. The overall goal is to advance knowledge about the spectral endmembers present in boreal landscape to improve the accuracy of the FSC estimates derived from the remote sensing observations and support better interpretation and validation of remote sensing observations over these heterogeneous landscapes. The main outcome from the work is that laboratory-controlled experiments that exclude disturbing factors present in field circumstances may provide more accurate representation of wet (melting) snow endmember reflectance for the FSC mapping method. The behavior of snow band reflectance is found to be insensitive to width and location differences between visible satellite sensor bands utilized in optical snow cover mapping which facilitates the use of various sensors for the construction of historical data records. The results also reveal the high deviation of snow reflectance due to heterogeneity in snow macro- and microstructural properties. The quantitative statistics of bulk snow properties show that areal averages derived from in-situ measurements and used to validate remote sensing observations are dependent on the measurement spacing and sample size especially over land covers with high absolute snow depth variability, such as barren lands in tundra. Applying similar sampling protocol (sample spacing and sample size) over boreal and tundra land cover types that represent very different snow characteristics will yield to non-equal representativeness of the areal mean values. The extensive datasets collected for this work demonstrate that observations measured at various scales can provide different view angle to the same challenge but at the same time any dataset individually cannot provide a full understanding of the target complexity. This work and the collected datasets directly facilitate further investigation of uncertainty in fractional snow cover maps retrieved by optical remote sensing and the interpretation of satellite observations in boreal and tundra landscapes. Note de contenu : 1. Introduction 2. Snow and its properties 3. Multispectral optical remote sensing of snow 4. Study site, datasets and methods 5. Results and discussion 6. Conclusions and future work Numéro de notice : 24060 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère Note de thèse : PhD Thesis : Sciences : University of Helsinki : 2022 DOI : 10.35614/isbn.9789523361522 En ligne : https://doi.org/10.35614/isbn.9789523361522 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101997

Habitat directive forest type western taiga (*9010) in Estonia : the first description of stand structure according to mapping and monitoring data / Anneli Palo in Baltic forestry, vol 21 n° 1 ([01/02/2015])  

Public [article]  inBaltic forestry > vol 21 n° 1 [01/02/2015] . - pp 16 - 27 Titre : Habitat directive forest type western taiga (*9010) in Estonia : the first description of stand structure according to mapping and monitoring data Type de document : Article/Communication Auteurs : Anneli Palo, Auteur ; Mark Gimbutas, Auteur Année de publication : 2015 Article en page(s) : pp 16 - 27 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] caractérisation [Termes IGN] composition floristique [Termes IGN] directive européenne [Termes IGN] Estonie [Termes IGN] habitat forestier [Termes IGN] peuplement forestier [Termes IGN] peuplement végétal [Termes IGN] régression logistique [Termes IGN] surveillance forestière [Termes IGN] taïga [Vedettes matières IGN] Ecologie forestière Résumé : (auteur) This paper provides a comparative description of the Estonian Western taiga habitat type (*9010) based on data from the national Habitat Directive Annex I forest habitat monitoring program and two regional studies. Various stand structure characteristics associated with forest representativity, continuity age, region and dominant tree species are analyzed using logistic regression and models for count data. We found that most of the studied characteristics show expressive regional differences. Many stands' traits are well associated with representativity grading and continuity age. To predict the presence of many structure characteristics, we found that it may be sufficient to know the forest's stand composition (coniferous, deciduous or mixed) instead of tree species. We conclude that the Estonian mapping and monitoring methodologies are well-suited to describing and assessing the quality of the Western taiga habitat type in Estonia. Numéro de notice : A2015-674 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : sans En ligne : https://balticforestry.lammc.lt/bf/PDF_Articles/2015-21[1]/Habitat%20Directive%2 [...] Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78297 [article]

Tree cover and height estimation in the Fennoscandian tundra-taiga transition zone using multiangular MISR data / J. Heiskanen in Remote sensing of environment, vol 103 n° 1 (15 July 2006)  

Public [article]  inRemote sensing of environment > vol 103 n° 1 (15 July 2006) . - pp 97 - 114 Titre : Tree cover and height estimation in the Fennoscandian tundra-taiga transition zone using multiangular MISR data Type de document : Article/Communication Auteurs : J. Heiskanen, Auteur Année de publication : 2006 Article en page(s) : pp 97 - 114 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] arbre (flore) [Termes IGN] classification par réseau neuronal [Termes IGN] détection de changement [Termes IGN] Finlande [Termes IGN] forêt boréale [Termes IGN] image Terra-MISR [Termes IGN] taïga [Termes IGN] toundra Résumé : (Auteur) The tundra–taiga transition zone stretches around the northern hemisphere separating boreal forest to the south from treeless tundra to the north. Tree cover and height are important variables to characterize this vegetation transition. Accurate continuous fields of tree cover and height would enable the delineation of the forest extent according to different criterion and provide useful data for change detection of this climatically sensitive ecotone. This study examined if multiangular remote sensing data has potential to improve the accuracy of the tree cover and height estimates in relation to nadir-view data. The satellite data consisted of Multi-angle Imaging SpectroRadiometer (MISR) data at 275 m and 1.1 km resolutions. The study area was located in the Fennoscandian tundra–taiga transition zone, in northernmost Finland. The continuous fields of tree cover and height were estimated using neural networks, which were trained and assessed by high-resolution biotope inventory data. The spectral–angular data together produced lower estimation errors than single band nadir, multispectral nadir or single band multiangular data alone. RMSE of the tree cover estimates reduced from 7.8% (relative RMSE 67.4%) to 6.5% (56.1%) at 275 m resolution, and from 5.4% (49.2%) to 4.1% (36.9%) at 1.1 km resolution, when multispectral nadir data were used together with multiangular data. RMSE of the tree height estimates reduced from 2.3 m (44.3%) to 2.0 m (37.6%) and from 1.8 m (35.4%) to 1.3 m (25.4%), respectively. The largest estimation errors occurred in mires and in areas of dense shrub cover, but the use of multiangular data also reduced estimation errors in these areas. The results suggest that directional information has potential to improve the tree cover and height estimates, and hence the accuracy of the land cover change detection in the tundra–taiga transition zone. Copyright Elsevier Numéro de notice : A2006-285 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2006.03.015 En ligne : https://doi.org/10.1016/j.rse.2006.03.015 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28012 [article]

Les formations végétales du globe / P. Birot (1965)

Public Titre : Les formations végétales du globe Type de document : Monographie Auteurs : P. Birot, Auteur Editeur : Paris : SEDES Année de publication : 1965 Importance : 508 p. Format : 17 x 24 cm Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Ecologie [Termes IGN] algue [Termes IGN] biologie [Termes IGN] climat aride [Termes IGN] désert [Termes IGN] forêt [Termes IGN] formation végétale [Termes IGN] incendie [Termes IGN] monde (géographie physique) [Termes IGN] pédologie [Termes IGN] rayonnement lumineux [Termes IGN] sécheresse [Termes IGN] taïga [Termes IGN] température de surface [Termes IGN] toundra [Termes IGN] vent Numéro de notice : 46187 Affiliation des auteurs : non IGN Thématique : FORET Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=58477

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
46187-01	48.00	Livre	Centre de documentation	Végétation - Forêt	Disponible