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Roles of horizontal and vertical tree canopy structure in mitigating daytime and nighttime urban heat island effects / Jike Chen in International journal of applied Earth observation and geoinformation, vol 89 (July 2020)  

Public [article]  inInternational journal of applied Earth observation and geoinformation > vol 89 (July 2020) . - n° 102060 Titre : Roles of horizontal and vertical tree canopy structure in mitigating daytime and nighttime urban heat island effects Type de document : Article/Communication Auteurs : Jike Chen, Auteur ; Shuanggen Jin, Auteur ; Peijun Du, Auteur Année de publication : 2020 Article en page(s) : n° 102060 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes descripteurs IGN] arbre urbain [Termes descripteurs IGN] canopée [Termes descripteurs IGN] carte de la végétation [Termes descripteurs IGN] couvert forestier [Termes descripteurs IGN] données lidar [Termes descripteurs IGN] ilot thermique urbain [Termes descripteurs IGN] modèle numérique de terrain [Termes descripteurs IGN] Nankin (Kiangsou) [Termes descripteurs IGN] occupation du sol [Termes descripteurs IGN] régression linéaire [Termes descripteurs IGN] semis de points [Termes descripteurs IGN] température au sol Résumé : (auteur) The urban heat island (UHI) is increasingly recognized as a serious, worldwide problem because of urbanization and climate change. Urban vegetation is capable of alleviating UHI and improving urban environment by shading together with evapotranspiration. While the impacts of abundance and spatial configuration of vegetation on land surface temperature (LST) have been widely examined, very little attention has been paid to the role of vertical structure of vegetation in regulating LST. In this study, we investigated the relationships between horizontal/vertical structure characteristics of urban tree canopy and LST as well as diurnal divergence in Nanjing City, China, with the help of high resolution vegetation map, Light Detection and Ranging (LiDAR) data and various statistical analysis methods. The results indicated that composition, configuration and vertical structure of tree canopy were all significantly related to both daytime LST and nighttime LST. Tree canopy showed stronger influence on LST during the day than at night. Note that the contribution of composition of tree canopy to explaining spatial heterogeneity of LST, regardless of day and night, was the highest, followed by vertical structure and configuration. Combining composition, configuration and vertical structure of tree canopy can take advantage of their respective advantages, and best explain variation in both daytime LST and nighttime LST. As for the independent importance of factors affecting spatial variation of LST, percent cover of tree canopy (PLAND), mean tree canopy height (TH_Mean), amplitude of tree canopy height (TA) and patch cohesion index (COHESION) were the most influential during the day, while the most important variables were PLAND, maximum height of tree canopy (TH_Max), variance of tree canopy height (TH_SD) and COHESION at night. This research extends our understanding of the impacts of urban trees on the UHI effect from the horizontal to three-dimensional space. In addition, it may offer sustainable and effective strategies for urban designers and planners to cope with increasing temperature. Numéro de notice : A2020-715 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1016/j.jag.2020.102060 date de publication en ligne : 25/02/2020 En ligne : https://doi.org/10.1016/j.jag.2020.102060 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96285 [article]

Co-seismic displacement and waveforms of the 2018 Alaska earthquake from high-rate GPS PPP velocity estimation / Shuanggen Jin in Journal of geodesy, vol 93 n° 9 (September 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 9 (September 2019) . - pp 1559 - 1569 Titre : Co-seismic displacement and waveforms of the 2018 Alaska earthquake from high-rate GPS PPP velocity estimation Type de document : Article/Communication Auteurs : Shuanggen Jin, Auteur ; Ke Su, Auteur Année de publication : 2019 Article en page(s) : pp 1559 - 1569 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] Alaska (Etats-Unis) [Termes descripteurs IGN] déformation de la croute terrestre [Termes descripteurs IGN] positionnement cinématique [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] séisme [Termes descripteurs IGN] vitesse de déplacement Résumé : (Auteur) For earthquake and tsunami early warning and emergency response, the parameters of earthquakes should be determined rapidly and correctly. The precise displacement time series can be obtained from high-rate GPS precise point positioning (PPP) during the earthquake, but require long convergence time. In this paper, the PPP velocity estimation (PPPVE) approach is applied to estimate the velocity waveforms and integrate to displacement waveforms in real-time scenarios. A case study of the 2018 Alaska earthquake is conducted from 1 Hz GPS data. The accuracy of velocity and displacement waveforms for 1 Hz GPS data is analyzed by comparing PPPVE-derived displacements with kinematic PPP solution. The results indicate that PPP and PPPVE are both capable of detecting seismic displacement waveforms with amplitude of 1 cm horizontally, while PPPVE can detect the displacement waveforms with much faster convergence speed. The mean convergence time of PPPVE for north, east and up components are 19, 22 and 31 s, respectively. The derived ground motion parameters estimate a magnitude of Mw = 7.97 ± 0.18, showing a great consistency and agreement with the seismometer magnitude. The preliminary relationship between the seismic intensity and ground motion parameters is established and evaluated for an auxiliary reference. Furthermore, the permanent displacement induced by the earthquake is obtained from real-time PPPVE approach. The benefits of PPPVE approach for GNSS seismology are demonstrated. Numéro de notice : A2019-506 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01269-3 date de publication en ligne : 24/06/2019 En ligne : https://doi.org/10.1007/s00190-019-01269-3 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93789 [article]