Search results for " global sensitivity"
showing 4 items of 4 documents
Global Sensitivity Analysis of Leaf-Canopy-Atmosphere RTMs: Implications for Biophysical Variables Retrieval from Top-of-Atmosphere Radiance Data.
2019
Knowledge of key variables driving the top of the atmosphere (TOA) radiance over a vegetated surface is an important step to derive biophysical variables from TOA radiance data, e.g., as observed by an optical satellite. Coupled leaf-canopy-atmosphere Radiative Transfer Models (RTMs) allow linking vegetation variables directly to the at-sensor TOA radiance measured. Global Sensitivity Analysis (GSA) of RTMs enables the computation of the total contribution of each input variable to the output variance. We determined the impacts of the leaf-canopy-atmosphere variables into TOA radiance using the GSA to gain insights into retrievable variables. The leaf and canopy RTM PROSAIL was coupled with…
A comprehensive analysis for N2O mechanisms by advanced mathematical techniques
2018
Recent evaluation of the existing activated sludge models, incorporating nitrous oxide (N2O) formation, is only based on the capabilities and inabilities in describing experimental data under different conditions. This paper will present an advanced mathematical modeling framework (i.e. coupling global sensitivity, identifiability and uncertainty analysis) for a comprehensive analysis on the evaluation of the structural differences among three ammonia oxidizing bacteria (AOB) two-pathway models in combination with two heterotrophic denitrification models. The analysis will be performed based on experimental data from a lab-scale deammonification granular sequencing batch reactor operated un…
Emulation of Leaf, Canopy and Atmosphere Radiative Transfer Models for Fast Global Sensitivity Analysis
2016
Physically-based radiative transfer models (RTMs) help understand the interactions of radiation with vegetation and atmosphere. However, advanced RTMs can be computationally burdensome, which makes them impractical in many real applications, especially when many state conditions and model couplings need to be studied. To overcome this problem, it is proposed to substitute RTMs through surrogate meta-models also named emulators. Emulators approximate the functioning of RTMs through statistical learning regression methods, and can open many new applications because of their computational efficiency and outstanding accuracy. Emulators allow fast global sensitivity analysis (GSA) studies on adv…
Sensitivity analysis: fundamentals
2015
Sensitivity analysis (SA) is a valuable tool to support the use of mathematical models for environmental systems. Local or global SA (namely, LSA and GSA) are performed in order to better understand processes and to select the most influential factors affecting processes. The main objective of this extended abstract is to provide an informed problem statement of the issues surrounding LSA and GSA applications in the environmental water quality modelling field. Specifically, this paper aims at identifying, for the most popular methods, their potential use, the critical issues to be solved and the limits identified in a comprehensive literature review.