Department of Mathematics

Complex system working lunch (CoSy): Towards a flexible statistical modelling by latent factors for evaluation of simulated responses to climate forcings

  • Date: 24 April, 12:15–13:00
  • Location: Ångströmlaboratoriet, Lägerhyddsvägen 1 Å4003
  • Lecturer: Ekaterina Fetisova
  • Organiser: CIM
  • Contact person: Marcus Westerberg
  • Seminarium

In my talk, I will present a new flexible statistical framework developed for evaluation of temperature data, generated by sophisticated climate models, against observational data. The framework includes several so-called Structural Equation Models (SEM) with latent variables, subsuming also such models as Measurement Error (ME) models and Confirmatory Factor Analysis (CFA) models. Evaluation of climate model simulations is accomplished by assessing whether latent temperature responses to different climate forcings (such as solar, orbital, volcanic etc.) are correctly represented in climate model simulations, compared to the corresponding true temperature responses embedded in observational data. In addition, the framework allows researchers to investigate the underlying latent structure of temperature data and to make statistical inferences about influences of the forcings on the temperature. The flexibility of the framework is reflected in its ability to take into account the number of forcings, their climate-relevant properties, and our substantive knowledge about possible (causal) relationships between temperature responses to various forcings. The performance of some ME-, CFA- and SEM-models is evaluated and compared in a pseudo-proxy experiment, where observational data are replaced by temperature data from a selected climate model simulations. This replacement ensures that latent temperature responses are indeed correctly represented in the climate model simulations under study. Nevertheless, the underlying structure remains unknown. The results of the experiment indicated that the underlying latent structure of the temperature data under consideration is too complicated to be described by ME models. Depending on the region under consideration, either a CFA- or SEM-model is required to provide an acceptable and climatologically defensible description of the underlying latent structure of the temperature data.