Sökning: "African Sahel"

Visar resultat 1 - 5 av 8 avhandlingar innehållade orden African Sahel.

  1. 1. Mapping Primary Production for the West African Sahel with Satellite Data

    Detta är en avhandling från Department of Physical Geography, Lund University

    Författare :Jonathan Seaquist; Lund University.; Lunds universitet.; [2001]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physical geography; Sahel; CENTURY; Monte Carlo; GPP; transpiration; LUE; CLAVR; PAR; compositing; MVC; geostatistics; noise; NDVI; NOAA AVHRR; geomorphology; pedology; cartography; climatology; Fysisk geografi; geomorfologi; marklära; kartografi; klimatologi;

    Sammanfattning : A light Use Efficiency (LUE) model is developed that allows the mapping of total growing season Gross Primary Production (GPP) for the West African Sahel, using the Normalized Difference Vegetation Index (NDVI) together with other data. Image quality may be poor in monthly NDVI maximum value composites as shown by an improved geostatistical noise estimation technique. LÄS MER

  2. 2. On Sahelian-Sudan rainfall and its moisture sources

    Detta är en avhandling från Stockholm : Department of Meteorology, Stockholm University

    Författare :Abubakr A. M. Salih; Stockholms universitet.; [2015]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sudan; Sahel; rainfall; land use; deforestation; moisture sources; moisture transport; Lagrangian; moisture tagging; regional model; climate modeling; Atmospheric Sciences and Oceanography; atmosfärvetenskap och oceanografi;

    Sammanfattning : The African Sahel is one of the most vulnerable regions to climate variability at different time scales. It is an arid to semi-arid region with limited water resources. The summer rainfall is one of these sources, but it exhibits pronounced interannual variability. This thesis presents several aspects of Sahelian Sudan rainfall. LÄS MER

  3. 3. Spatio-Temporal Estimation for Mixture Models and Gaussian Markov Random Fields - Applications to Video Analysis and Environmental Modelling

    Detta är en avhandling från Lund University

    Författare :Johan Lindström; Lund University.; Lunds universitet.; [2008]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; vegetation; time series analysis; video segmentation; spatio-temporal modelling; precipitation; Markov chain Monte Carlo; Gaussian Markov random fields; expectation maximisation; change point detection; Bayesian recursive estimation; African Sahel; adaptive Gaussian mixtures;

    Sammanfattning : In this thesis computationally intensive methods are used to estimate models and to make inference for large, spatio-temporal data sets. The thesis is divided into two parts: the first two papers are concerned with video analysis, while the last three papers model and investigate environmental data from the Sahel area in northern Africa. LÄS MER

  4. 4. Linking Landscapes and Livelihoods : Ecosystem services as a lens in Sudano-Sahelian West Africa

    Detta är en avhandling från Stockholm Resilience Centre, Stockholm University

    Författare :Hanna Sinare; Stockholms universitet.; [2013]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ecosystem services; landscapes; livelihoods; agroforestry; Sudano-Sahel; West Africa; Natural Resources Management; naturresurshushållning;

    Sammanfattning : Integrated landscape approaches are increasingly called for to reconcile multiple objectives from the perspectives of agriculture, forestry, poverty alleviation and biodiversity conservation. Sudano-Sahelian West Africa with low agricultural productivity and widespread poverty is a hotspot for these issues and has attracted international interest in interventions to improve livelihoods. LÄS MER

  5. 5. Primary Production in African Drylands : Quantifying Supply and Demand Using Earth Observation and Socio-ecological Data

    Detta är en avhandling från Lund University, Faculty of Science, Department of Physical Geography and Ecosystem Science

    Författare :Abdulhakim Abdi; Lund University.; Lunds universitet.; [2017-02]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Net Primary Production NPP ; Africa; Drylands; Coupled Human and Natural Systems; Human-Environment Relations; Food; Fuel; Feed; Earth Observation; Remote Sensing; Biomass; Carbon; Supply and Demand;

    Sammanfattning : The human-environment connection in the mostly rural drylands of sub-Saharan Africa forms a complex, interlinked system that provides ecosystem services. This system is susceptible to climatic variability that impacts the supply of its products, and high population growth, which impacts the demand for these products. LÄS MER