Preprints
https://doi.org/10.5194/egusphere-2022-849
https://doi.org/10.5194/egusphere-2022-849
08 Nov 2022
 | 08 Nov 2022

Using Probability Density Functions to Evaluate Models (PDFEM, v1.0) to compare a biogeochemical model with satellite derived chlorophyll

Bror Fredrik Jönsson, Christopher Follett, Jacob Bien, Stephanie Dutkiewicz, Sangwon Hyun, Gemma Kulk, Gael Forget, Christian Müller, Marie-Fanny Racault, Christopher Nigel Hill, Thomas Jackson, and Shubha Sathyendranath

Abstract. Global biogeochemical ocean models are invaluable tools to examine how physical, chemical, and biological processes interact in the ocean. Satellite-derived ocean-color properties, on the other hand, provide observations of the surface ocean with unprecedented coverage and resolution. Advances in our understanding of marine ecosystems and biogeochemistry are strengthened by the combined use of these resources, together with sparse in situ data. Recent modeling advances allow simulation of the spectral properties of phytoplankton and remote-sensing reflectances, bringing model outputs closer to the kind of data that ocean-color satellites can provide. However, comparisons between model outputs and analogous satellite products (e.g. chlorophyll-a) remain problematic: Most evaluations are based on point-by-point comparisons in space and time where spuriously large errors can occur from small spatial and temporal mismatches, whereas global statistics provide no information on how well a model resolves processes at regional scales. Here, we employ a unique suite of methodologies, Probability Density Functions to Evaluate Models (PDFEM), which generate a robust comparison of these resources. The probability density functions of physical and biological properties of Longhurst's provinces are compared, to evaluate how well a model resolves related processes. Differences in the distributions of chlorophyll-a concentration [mg m-3] provide information on matches and mismatches between models and observations. In particular, mismatches help isolate regional sources of discrepancy, which can lead to improving both simulations and satellite algorithms. Furthermore, the use of radiative transfer in the model to mimic remotely-sensed products facilitate model-observation comparisons of optical properties of the ocean.

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Journal article(s) based on this preprint

18 Aug 2023
Using Probability Density Functions to Evaluate Models (PDFEM, v1.0) to compare a biogeochemical model with satellite-derived chlorophyll
Bror F. Jönsson, Christopher L. Follett, Jacob Bien, Stephanie Dutkiewicz, Sangwon Hyun, Gemma Kulk, Gael L. Forget, Christian Müller, Marie-Fanny Racault, Christopher N. Hill, Thomas Jackson, and Shubha Sathyendranath
Geosci. Model Dev., 16, 4639–4657, https://doi.org/10.5194/gmd-16-4639-2023,https://doi.org/10.5194/gmd-16-4639-2023, 2023
Short summary
Bror Fredrik Jönsson, Christopher Follett, Jacob Bien, Stephanie Dutkiewicz, Sangwon Hyun, Gemma Kulk, Gael Forget, Christian Müller, Marie-Fanny Racault, Christopher Nigel Hill, Thomas Jackson, and Shubha Sathyendranath

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-849', Lester Kwiatkowski, 05 Dec 2022
  • RC2: 'Comment on egusphere-2022-849', Marcello Vichi, 05 Feb 2023
  • AC1: 'Comment on egusphere-2022-849', Bror Jonsson, 22 Mar 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-849', Lester Kwiatkowski, 05 Dec 2022
  • RC2: 'Comment on egusphere-2022-849', Marcello Vichi, 05 Feb 2023
  • AC1: 'Comment on egusphere-2022-849', Bror Jonsson, 22 Mar 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Bror Jonsson on behalf of the Authors (19 Apr 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (20 Apr 2023) by Andrew Yool
AR by Bror Jonsson on behalf of the Authors (05 May 2023)

Journal article(s) based on this preprint

18 Aug 2023
Using Probability Density Functions to Evaluate Models (PDFEM, v1.0) to compare a biogeochemical model with satellite-derived chlorophyll
Bror F. Jönsson, Christopher L. Follett, Jacob Bien, Stephanie Dutkiewicz, Sangwon Hyun, Gemma Kulk, Gael L. Forget, Christian Müller, Marie-Fanny Racault, Christopher N. Hill, Thomas Jackson, and Shubha Sathyendranath
Geosci. Model Dev., 16, 4639–4657, https://doi.org/10.5194/gmd-16-4639-2023,https://doi.org/10.5194/gmd-16-4639-2023, 2023
Short summary
Bror Fredrik Jönsson, Christopher Follett, Jacob Bien, Stephanie Dutkiewicz, Sangwon Hyun, Gemma Kulk, Gael Forget, Christian Müller, Marie-Fanny Racault, Christopher Nigel Hill, Thomas Jackson, and Shubha Sathyendranath
Bror Fredrik Jönsson, Christopher Follett, Jacob Bien, Stephanie Dutkiewicz, Sangwon Hyun, Gemma Kulk, Gael Forget, Christian Müller, Marie-Fanny Racault, Christopher Nigel Hill, Thomas Jackson, and Shubha Sathyendranath

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Short summary
While biogeochemical models and satellite-derived ocean-color data provide unprecedented information it is problematic to compare them. Here, we present a new approach based on comparing probability density distributions of model and satellite properties to assess model skills. We also introduce Earth Mover Distances as a novel and powerful metric to quantify the misfit between models and observations. We find that how 3D chlorophyll fields are aggregated can be a significant source of error.