A piecewise modeling approach for climate sensitivity studies: Tests with a shallow-water model

Aimei Shao, Chongjian Qiu, Guo-Yue Niu

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

In model-based climate sensitivity studies, model errors may grow during continuous long-term integrations in both the “reference” and “perturbed” states and hence the climate sensitivity (defined as the difference between the two states). To reduce the errors, we propose a piecewise modeling approach that splits the continuous long-term simulation into subintervals of sequential short-term simulations, and updates the modeled states through re-initialization at the end of each subinterval. In the re-initialization processes, this approach updates the reference state with analysis data and updates the perturbed states with the sum of analysis data and the difference between the perturbed and the reference states, thereby improving the credibility of the modeled climate sensitivity. We conducted a series of experiments with a shallow-water model to evaluate the advantages of the piecewise approach over the conventional continuous modeling approach. We then investigated the impacts of analysis data error and subinterval length used in the piecewise approach on the simulations of the reference and perturbed states as well as the resulting climate sensitivity. The experiments show that the piecewise approach reduces the errors produced by the conventional continuous modeling approach, more effectively when the analysis data error becomes smaller and the subinterval length is shorter. In addition, we employed a nudging assimilation technique to solve possible spin-up problems caused by re-initializations by using analysis data that contain inconsistent errors between mass and velocity. The nudging technique can effectively diminish the spin-up problem, resulting in a higher modeling skill.

Original languageEnglish (US)
Pages (from-to)735-746
Number of pages12
JournalJournal of Meteorological Research
Volume29
Issue number5
DOIs
StatePublished - 2015

Keywords

  • Climate sensitivity
  • Model uncertainty
  • Modeling approach
  • Nudging technique

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Ocean Engineering
  • Hardware and Architecture
  • Computer Science Applications
  • Atmospheric Science

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