Using a thermal-based two source energy balance model with time-differencing to estimate surface energy fluxes with day-night MODIS observations

The Dual Temperature Difference (DTD) model, introduced by Norman et al. (2000), uses a two source energy balance modelling scheme driven by remotely sensed observations of diurnal changes in land surface temperature (LST) to estimate surface energy fluxes. By using a time-differential temperature measurement as input, the approach reduces model sensitivity to errors in absolute temperature retrieval. The original formulation of the DTD required an early morning LST observation (approximately 1 h after sunrise) when surface fluxes are minimal, limiting application to data provided by geostationary satellites at sub-hourly temporal resolution. The DTD model has been applied primarily during the active growth phase of agricultural crops and rangeland vegetation grasses, and has not been rigorously evaluated during senescence or in forested ecosystems. In this paper we present modifications to the DTD model that enable applications using thermal observations from polar orbiting satellites, such as Terra and Aqua, with day and night overpass times over the area of interest. This allows the application of the DTD model in high latitude regions where large viewing angles preclude the use of geostationary satellites, and also exploits the higher spatial resolution provided by polar orbiting satellites. A method for estimating nocturnal surface fluxes and a scheme for estimating the fraction of green vegetation are developed and evaluated. Modification for green vegetation fraction leads to significantly improved estimation of the heat fluxes from the vegetation canopy during senescence and in forests. When the modified DTD model is run with LST measurements acquired with the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra and Aqua satellites, generally satisfactory agreement with field measurements is obtained for a number of ecosystems in Denmark and the United States. Finally, regional maps of energy fluxes are produced for the Danish Hydrological ObsErvatory (HOBE) in western Denmark, indicating realistic patterns based on land use

Recovering land surface temperature under cloudy skies considering the solar‐cloud‐satellite geometry: application to MODIS and Landsat‐8 data

Clouds play a significant role in the derivation of land surface temperature (LST) from optical remote sensing. The estimation of LST under cloudy sky conditions has been a great challenge for the community for a long time. In this study, a scheme for recovering the LST under cloudy skies is proposed by accounting for the solar‐cloud‐satellite geometry effect, through which the LSTs of shadowed and illuminated pixels covered by clouds in the image are estimated. The validation shows that the new scheme can work well and has reasonable LST accuracy with a root mean square error < 4.9 K and bias < 3.5 K. The application of the new method to the Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat‐8 data reveals that the LSTs under cloud layers can be reasonably recovered and that the fraction of valid LSTs in an image can be correspondingly improved. The method is not data specific; instead, it can be used in any optical remote sensing images as long as the proper input variables are provided. As an alternative approach to derive cloudy sky LSTs based only on optical remote sensing data, it gives some new ideas to the remote sensing community, especially in the fields of surface energy balance

Détection de points chauds de déforestation à Bornéo de 2000 à 2009 à partir d'images MODIS

Ce travail s’inscrit dans le cadre d’un programme de recherches appuyé par le Conseil de recherches en sciences humaines du Canada.Les forêts de Bornéo sont inestimables. En plus d’une faune et d’une flore riche et diversifiée, ses milieux naturels constituent d’efficaces réservoirs de carbone. En outre, la matière ligneuse qui y est abondante fait l’objet d’une exploitation intensive. Par contre, c’est le potentiel agricole de l’île qui crée le plus d’enthousiasme, principalement en ce qui concerne la culture du palmier à huile. Pour tenter de mieux comprendre et surveiller le phénomène, nous avons développé des méthodes de détection de la déforestation et de la dégradation des forêts. Ces méthodes doivent tenir compte des caractéristiques propres à l’île. C’est que Bornéo est abondamment affectée par une nébulosité constante qui complexifie considérablement son observation à partir des satellites. Malgré ces contraintes, nous avons produit une série chronologique annuelle des points chauds de déforestation et de dégradation des forêts pour les années 2000 à 2009.Borneo’s forests are priceless. Beyond the richness and diversity of its fauna and flora, its natural habitats constitute efficient carbon reservoirs. Unfortunately, the vast forests of the island are rapidly being cut down, both by the forestry industry and the rapidly expanding oil palm industry. In this context, we’ve developed methods to detect deforestation and forest degradation in order to better understand and monitor the phenomena. In doing so, the peculiarities of Borneo, such as the persistent cloud cover, had to be accounted for. Nevertheless, we succeeded in producing a time series of the yearly forest degradation and deforestations hotspots for the year 2000 through the year 2009

Contribution de la mission SWOT pour le suivi des étendues et niveaux d’eau dans les milieux humides boréaux

Il est estimé que les milieux humides constituent entre 5% à 8% du couvert terrestre. Ceux-ci sont d’une importance particulière puisqu’ils remplissent de nombreuses fonctions essentielles à la santé et prospérité de plusieurs espèces vivantes. Cependant, il est estimé que les milieux humides ont globalement perdu environ 21% de leur superficie depuis le début des années 1700. De nombreux efforts ont depuis été mis en place pour réduire et remédier à cette perte. Une saine gestion des milieux humides utilise donc plusieurs méthodes de surveillance, particulièrement pour les fluctuations des niveaux et étendues d’eau. La télédétection offre un grand éventail d’outils pour la détection des eaux en milieu humide. Les données optiques et radars à synthèse d’ouverture (RSO) permettent la délimitation des étendues d’eau et les missions altimétriques mesurent l’élévation de l’eau de façon relativement précise, mais avec une couverture spatiale limitée. La mission Surface Water and Ocean Topography (SWOT) regroupe ces deux types de mesures sous une seule mission et procurera des données d’élévation spatialisées pour plus de 90% de la Terre. Cette thèse porte sur le potentiel et les enjeux que SWOT pourrait rencontrer pour la détection des plans d’eau dans les milieux humides boréaux. Les objectifs principaux sont, d’abord, d’évaluer de multiples missions satellitaires pour la détection d’un évènement d’inondation extrême en milieu humide boréal afin de dégager le potentiel de SWOT et ensuite d’analyser l’impact de la végétation sur la capacité de SWOT à détecter les plans d’eaux. Brièvement, les simulateurs SWOT large échelle (SWOT-LS) et SWOT haute résolution (SWOT-HR) ont été utilisés pour simuler des données SWOT afin de répondre aux objectifs de recherche. D’abord, l’été 2020 a vu l’un des plus importants évènements d’inondations sur le delta des rivières de la Paix et Athabasca (PAD) depuis l’inondation de 1935. C’est une excellente opportunité d’évaluer la capacité d’une multitude de missions satellitaires ainsi que celle du satellite SWOT pour le suivi d’un tel évènement en milieux humides. Le chapitre 4, présenté sous la forme d’un article scientifique, se concentre donc sur l’utilisation de SWOT-LS pour simuler une série temporelle de données SWOT durant un épisode d’inondation extrême sur le PAD à l’été 2020. La détection de l’évolution des étendues d’eau est aussi évaluée pour les missions Sentinel-1, Sentinel-2, Landsat-8 et RADARSAT Constellation tandis que les niveaux d’eau sont évalués pour les missions Sentinel-3 et Jason-3. Ensuite, le chapitre 5, aussi présenté sous la forme d’un article scientifique, évalue l’impact de la végétation aquatique et émergente sur le signal SWOT à l’aide de SWOT-HR. Des données de coefficent de rétrodiffusion provenant de la mission AirSWOT lors d’un survol au-dessus du PAD en 2017 ont été utilisées comme données d’entrée afin d’avoir une meilleure représentation des valeurs attendues du signal SWOT dans un tel environnement. L’ensemble de ces résultats permet de brosser un portrait du potentiel et des enjeux du satellite SWOT pour la détection des plans d’eaux en milieux humides boréaux

Multi-Decadal Space-Based Observations of Basaltic Effusive Eruptions from MODIS Infrared Data.

Ph.D. Thesis. University of Hawaiʻi at Mānoa 2018

Biomass Burning and Its Relationship with Water Cycle Dynamics of the Chari-Logone Catchment of Lake Chad Basin

Title from PDF of title page viewed July 13, 2021Thesis advisor: Jejung LeeVitaIncludes bibliographical references (pages 98-105)Thesis (M.S.)--Department of Geosciences. University of Missouri--Kansas City, 2018The present study investigates the effect of biomass burning on the water cycle dynamics of the Chari-Logone catchment, which is the primary water source of Lake Chad, in central sub-Saharn Africa, providing approximately 95% of surface water inflow to the lake. A significant challenge in calculating water balance for this region is the lack of meteorological station data and the low temporal frequency of sampling by the few existing stations. WetSpass-M, a monthly water balance model, was chosen for this study due to its ability to calculate water balance without the large amount of data that many other models require. Satellite observations from TRMM, MODIS, and SRTM, and other earth science missions provide well distributed data at reasonable spatial scales. For a more comprehensive look at the effects of burning, i.e. albedo change, which has been shown to have a significant impact on a number of environmental factors, was considered when calculating potential evapotranspiration as a model input. Two water balance simulations, one considering burning and one without, were compared from the years 2003 to 2011. A groundwater model was also built using Processing MODFLOW, using actual evapotranspiration from both burning and non-burning water balance outputs. The resulting calculated runoff from the model agreed well with ground observations, with a Nashe-Sutcliffe Efficiency of 0.57. Seasonal analysis shows a correlation between water-cycle parameters and burning, and is affected by the region's seasonal variability, where burning increases during the dry season and decreases during the wet season. The groundwater model performed well for dry season months when there was less rainfall. However, when wet season evapotranspiration (ET) was used, the model over exaggerated the groundwater levels. This was most likely due to the way the groundwater and evapotranspiration parameters are handled in WetSpass-M. When the primary land cover types were studied (grass, savanna, and cropland); all three land cover types showed a significant reduction in ET. This is shown by average wet season ET decreasing -5.E+13 m³per month and a decrease 7.E+13 m³for the dry season months. This lends support to the hypothesis that with increased burning, there is a decrease in certain hydrologic parameters including precipitation.Introduction -- Literature review -- Methodology -- Results -- Conclusion -- Appendix A. WetSpass-M Land Use Look-up Table -- Appendix B. NOAA NCEI Global summaries of the day stations used for averaging monthly wind speed -- Appendix C. Python Program for Wind Speed Data -- Appendix D. Albedo Table of Land Use Without Fire -- Appendix E. Albedo Table of Land Use Considering Fire -- Appendix F. NOAA NCEI Climate Stations Used for Relative Humidity and to Calculate Extraterrestrial Radiation and Surface Radiation -- Appendix G.ASCII to Tiff Arcpy Tool -- Appendix H. Summation of Raster by Land Use Class Arcpy Tool -- Appendix I. BGR Stations Used for River Input in Groundwater Mode

Monitoring and modelling volcanoes with assessment of their hazards by means of remote sensing and analogue modelling

Many active volcanoes in developing countries are poorly-known and not monitored. This thesis investigates low cost solutions to map the topography, to identify hazards and to document the eruptions at volcanoes with satellite data. Using a combination of remote sensing techniques and analogue modelling, this thesis also contributes to the understanding of volcanic processes such as the controls upon the 3D shape of sub-volcanic intrusive systems, upon the location of eruption outbreaks, upon the variations in eruption intensity through time and upon the transition between contrasted eruptive styles at a single volcano. After reviewing previous applications of low cost remote sensing in volcanology, the accuracy of two topographic datasets derived from contrasted remote sensing data (ASTER and SRTM) is assessed for volcanic terrains. Oldoinyo Lengai, a natrocarbonatite stratovolcano in Tanzania, is used as an illustrative example of poorly-known volcanoes whose hazards need to be assessed and whose eruptive activity has to be monitored. Satellite images enable mapping, constraining volumes and characterizing surface features of three flank collapses and their associated deposits. An existing numerical model is applied to constrain the emplacement dynamics and the velocity of one of those debris avalanche flows. An algorithm is then presented to retrieve daily information about eruptive activity and its variation over an 8-year period using nighttime MODIS satellite data. Analysis of this time series enable to highlight the control of Earth tides on the timing of high intensity eruptions. The same algorithm, combined with field data and petrologic analyses, is used to document a voluminous lava flow eruption that occurred at Oldoinyo Lengai at the end of March 2006, providing insights into the structure of the shallow plumbing system of the volcano. Satellite data are finally combined with laboratory experiments simulating magma propagation in the Earth crust with sand and syrup or gelatin and water, to provide a better understanding of the control exerted by volcanic edifice load upon magma ascent. These experiments also enable to explain the links between magma ascent, volcano load, sub-volcanic intrusions, volcano surface deformation and location of volcanic vents at the base of large volcanoes

Automated dust storm detection using satellite images. Development of a computer system for the detection of dust storms from MODIS satellite images and the creation of a new dust storm database.

Dust storms are one of the natural hazards, which have increased in frequency in the recent years over Sahara desert, Australia, the Arabian Desert, Turkmenistan and northern China, which have worsened during the last decade. Dust storms increase air pollution, impact on urban areas and farms as well as affecting ground and air traffic. They cause damage to human health, reduce the temperature, cause damage to communication facilities, reduce visibility which delays both road and air traffic and impact on both urban and rural areas. Thus, it is important to know the causation, movement and radiation effects of dust storms. The monitoring and forecasting of dust storms is increasing in order to help governments reduce the negative impact of these storms. Satellite remote sensing is the most common method but its use over sandy ground is still limited as the two share similar characteristics. However, satellite remote sensing using true-colour images or estimates of aerosol optical thickness (AOT) and algorithms such as the deep blue algorithm have limitations for identifying dust storms. Many researchers have studied the detection of dust storms during daytime in a number of different regions of the world including China, Australia, America, and North Africa using a variety of satellite data but fewer studies have focused on detecting dust storms at night. The key elements of this present study are to use data from the Moderate Resolution Imaging Spectroradiometers on the Terra and Aqua satellites to develop more effective automated method for detecting dust storms during both day and night and generate a MODIS dust storm database.Libyan Centre for Remote Sensing and Space ScienceAppendix A was submitted with extra data files which are not available online