Parameter sensitivity analysis of a 1-D cold region lake model for land-surface schemes
Lakes might be sentinels of climate change, but the uncertainty in their main feedback to the atmosphere – heat-exchange fluxes – is often not considered within climate models. Additionally, these fluxes are seldom measured, hindering critical evaluation of model output. Analysis of the Canadian...
Main Authors: | , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2017-12-01
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Series: | Hydrology and Earth System Sciences |
Online Access: | https://www.hydrol-earth-syst-sci.net/21/6345/2017/hess-21-6345-2017.pdf |
Summary: | Lakes might be sentinels of climate change, but the uncertainty in their main
feedback to the atmosphere – heat-exchange fluxes – is often not considered
within climate models. Additionally, these fluxes are seldom measured,
hindering critical evaluation of model output. Analysis of the Canadian Small
Lake Model (CSLM), a one-dimensional integral lake model, was performed to
assess its ability to reproduce diurnal and seasonal variations in heat
fluxes and the sensitivity of simulated fluxes to changes in model
parameters, i.e., turbulent transport parameters and the light extinction
coefficient (<i>K</i><sub>d</sub>). A C++ open-source software package, Problem
Solving environment for Uncertainty Analysis and Design Exploration (PSUADE),
was used to perform sensitivity analysis (SA) and identify the parameters
that dominate model behavior. The generalized likelihood uncertainty
estimation (GLUE) was applied to quantify the fluxes' uncertainty, comparing
daily-averaged eddy-covariance observations to the output of CSLM. Seven
qualitative and two quantitative SA methods were tested, and the posterior
likelihoods of the modeled parameters, obtained from the GLUE analysis, were
used to determine the dominant parameters and the uncertainty in the modeled
fluxes. Despite the ubiquity of the equifinality issue – different
parameter-value combinations yielding equivalent results – the answer to the
question was unequivocal: <i>K</i><sub>d</sub>, a measure of how much light
penetrates the lake, dominates sensible and latent heat fluxes, and the
uncertainty in their estimates is strongly related to the accuracy with which
<i>K</i><sub>d</sub> is determined. This is important since accurate and continuous
measurements of <i>K</i><sub>d</sub> could reduce modeling uncertainty. |
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ISSN: | 1027-5606 1607-7938 |