Sökning: "Dynamic Global Vegetation Models DGVM"

Visar resultat 1 - 5 av 7 uppsatser innehållade orden Dynamic Global Vegetation Models DGVM.

1. 1. Applying LPJ-GUESS on the Arctic: A model evaluation and benchmarking study

   Master-uppsats, Lunds universitet/Institutionen för naturgeografi och ekosystemvetenskap

   Författare :Margot Jeanne Knapen; [2023]
   Nyckelord :Physical Geography and Ecosystem Analysis; LPJ-GUESS; Arctic; FLUXNET; Gross Primary Productivity; Ecosystem Respiration; Permafrost; Active Layer Thickness; Snow Depth; Earth and Environmental Sciences;

   Sammanfattning : Warming in the Arctic occurs at a much higher rate than the global average, which has a considerable impact on the Arctic terrestrial carbon cycle. Permafrost thawing can release substantial amounts of carbon, whilst tundra shrubification and tree-line advance, on the other hand, may compensate for this. LÄS MER

3. 2. Evaluating a new hydraulic implementation in LPJ-GUESS for three sites in north Europe

   Master-uppsats, Lunds universitet/Institutionen för naturgeografi och ekosystemvetenskap

   Författare :Carl Holmquist; [2023]
   Nyckelord :Physical Geography and Ecosystem analysis; LPJ-GUESS; drought; sensitivity analysis; evapotranspiration; gross primary production; hydraulic parameters; boreal forest.; Earth and Environmental Sciences;

   Sammanfattning : Drought is projected to increase in frequency and intensity and impacts trees with increased water stress and increased mortality rate. Water stresses can cause hydraulic failure-related mortality or carbon starvation due to tree species having different strategies to deal with water stresses. LÄS MER

4. 3. Multitask Convolutional Neural Network Emulators for Global Crop Models - Supervised Deep Learning in Large Hypercubes of Non-IID Data

   Master-uppsats, Lunds universitet/Matematisk statistik

   Författare :Amanda Nilsson; [2020]
   Nyckelord :Multitask Learning; Convolutional Neural Network CNN ; Branched Neural Network; Dynamic Global Vegetation Models DGVM ; Automated Feature Extraction; Feature Importance; Supervised Machine Learning; Emulator; Surrogate Model; Response Surface Model; Approximation Model; Metamodeling; Model Composition; Regularization; Robustness; Hyperparameter Optimization; Mathematics and Statistics;

   Sammanfattning : The aim of this thesis is to establish whether a neural network (NN) can be used for emulation of simulated global crop production - retrieved from the computationally demanding dynamic global vegetation model (DGVM) Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS). It has been devoted to elaboration with various types of neural network architectures: Branched NNs capable of processing inputs of mixed data types; Convolutional Neural Network (CNN) architectures able to perform automated temporal feature extraction of the given weather time series; simpler fully connected (FC) structures as well as Multitask NNs. LÄS MER

5. 4. Modelling global Gross Primary Production using the correlation between key leaf traits

   Kandidat-uppsats, Lunds universitet/Institutionen för naturgeografi och ekosystemvetenskap

   Författare :Alexandra Pongrácz; [2017]
   Nyckelord :ecosystem modelling; leaf longevity; leaf nitrogen content; leaf mass per area; LEIA; LPJ-GUESS; GPP; terrestrial biosphere; Earth and Environmental Sciences; Biology and Life Sciences;

   Sammanfattning : Sophisticated ecosystem models make it possible to evaluate the potential future changes of the carbon sequestration capacity of the terrestrial biosphere, as a response to the rapid environmental and climatic changes. Accuracy of model estimates is however strongly dependent on the parametrisation of driving parameters. LÄS MER

7. 5. Simulating current regional pattern and composition of Chilean native forests using a dynamic ecosystem model

   Master-uppsats, Lunds universitet/Institutionen för naturgeografi och ekosystemvetenskap

   Författare :Cristián Andrés Escobar Avaria; [2013]
   Nyckelord :South-central Chile; LPJ-GUESS; temperate rain forests; magellanic rainforests; Physical Geography and Ecosystem analysis; plant functional types; Earth and Environmental Sciences;

   Sammanfattning : Resumen Dentro de los recursos naturales más relevantes de Chile están los bosques nativos. A pesar de su amplia distribución en el país, su superficie ha sido drásticamente disminuida durante los dos últimos siglos, especialmente debido a los continuos cambios en el uso de la tierra asociados a la agricultura, a la tala selectiva, al monocultivo de especies exóticas y al desarrollo urbano. LÄS MER