TY - JOUR
T1 - Comparison of full and empirical Bayes approaches for inferring sea-level changes from tide-gauge data
AU - Piecuch, Christopher G.
AU - Huybers, Peter
AU - Tingley, Martin P.
N1 - Funding Information:
The first author was supported by NSF award 1558966 and NASA grant NNX14AJ515. The comments of two anonymous reviewers are gratefully acknowledged. Data were retrieved from the PSMSL database (http://www.psmsl.org/). The model code and solutions are available from the corresponding author upon request.
Publisher Copyright:
© 2017. American Geophysical Union. All Rights Reserved.
PY - 2017/3/1
Y1 - 2017/3/1
N2 - Tide-gauge data are one of the longest instrumental records of the ocean, but these data can be noisy, gappy, and biased. Previous studies have used empirical Bayes methods to infer the sea-level field from tide-gauge records but have not accounted for uncertainty in the estimation of model parameters. Here we compare to a fully Bayesian method that accounts for uncertainty in model parameters, and demonstrate that empirical Bayes methods underestimate the uncertainty in sea level inferred from tide-gauge records. We use a synthetic tide-gauge data set to assess the skill of the empirical and full Bayes methods. The empirical-Bayes credible intervals on the sea-level field are narrower and less reliable than the full-Bayes credible intervals: the empirical-Bayes 95% credible intervals are 42.8% narrower on average than are the full-Bayes 95% credible intervals; full-Bayes 95% credible intervals capture 95.6% of the true field values, while the empirical-Bayes 95% credible intervals capture only 77.1% of the true values, showing that parameter uncertainty has an important influence on the uncertainty of the inferred sea-level field. Most influential are uncertainties in model parameters for data biases (i.e., tide-gauge datums); letting data-bias parameters vary along with the sea-level process, but holding all other parameters fixed, the 95% credible intervals capture 92.8% of the true synthetic-field values. Results indicate that full Bayes methods are preferable for reconstructing sea-level estimates in cases where complete and accurate estimates of uncertainty are warranted.
AB - Tide-gauge data are one of the longest instrumental records of the ocean, but these data can be noisy, gappy, and biased. Previous studies have used empirical Bayes methods to infer the sea-level field from tide-gauge records but have not accounted for uncertainty in the estimation of model parameters. Here we compare to a fully Bayesian method that accounts for uncertainty in model parameters, and demonstrate that empirical Bayes methods underestimate the uncertainty in sea level inferred from tide-gauge records. We use a synthetic tide-gauge data set to assess the skill of the empirical and full Bayes methods. The empirical-Bayes credible intervals on the sea-level field are narrower and less reliable than the full-Bayes credible intervals: the empirical-Bayes 95% credible intervals are 42.8% narrower on average than are the full-Bayes 95% credible intervals; full-Bayes 95% credible intervals capture 95.6% of the true field values, while the empirical-Bayes 95% credible intervals capture only 77.1% of the true values, showing that parameter uncertainty has an important influence on the uncertainty of the inferred sea-level field. Most influential are uncertainties in model parameters for data biases (i.e., tide-gauge datums); letting data-bias parameters vary along with the sea-level process, but holding all other parameters fixed, the 95% credible intervals capture 92.8% of the true synthetic-field values. Results indicate that full Bayes methods are preferable for reconstructing sea-level estimates in cases where complete and accurate estimates of uncertainty are warranted.
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U2 - 10.1002/2016JC012506
DO - 10.1002/2016JC012506
M3 - Article
AN - SCOPUS:85017341907
VL - 122
SP - 2243
EP - 2258
JO - Journal of Geophysical Research: Oceans
JF - Journal of Geophysical Research: Oceans
SN - 2169-9275
IS - 3
ER -