Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 4.252 IF 4.252
  • IF 5-year value: 4.890 IF 5-year 4.890
  • CiteScore value: 4.49 CiteScore 4.49
  • SNIP value: 1.539 SNIP 1.539
  • SJR value: 2.404 SJR 2.404
  • IPP value: 4.28 IPP 4.28
  • h5-index value: 40 h5-index 40
  • Scimago H index value: 51 Scimago H index 51
Discussion papers
https://doi.org/10.5194/gmd-2018-311
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gmd-2018-311
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Model description paper 10 Jan 2019

Model description paper | 10 Jan 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Geoscientific Model Development (GMD).

Description and validation of an intermediate complexity model for ecosystem photosynthesis and evapo-transpiration: ACM-GPP-ETv1

Thomas Luke Smallman1,2 and Mathew Williams1,2 Thomas Luke Smallman and Mathew Williams
  • 1School of GeoSciences, University of Edinburgh, Edinburgh, UK
  • 2National Centre for Earth Observations, University of Edinburgh, UK

Abstract. Photosynthesis (gross primary production, GPP) and evapo-transpiration (ET) are ecosystem processes with global significance for the carbon cycle, climate, hydrology and a range of ecosystem services. The mechanisms governing these processes are complex but well understood. There is strong coupling between these processes, mediated directly by stomatal conductance and indirectly by root zone soil moisture. This coupling must be effectively modelled for robust predictions of earth system responses to global change. It is highly demanding to model cellular processes, like stomatal conductance or electron transport, with responses times of minutes, over decadal and global domains. computational demand means models resolving this level of complexity cannot be fully evaluated for their parameter sensitivity, nor calibrated using earth observation data through data assimilation approaches requiring large ensembles. To resolve this problem, here we describe a coupled photosynthesis evapo-transpiration model of intermediate complexity. The model reduces computational load and parameter numbers by operating at canopy scale and daily time steps. But by including simplified representation of key process interactions it retains sensitivity to variation in climate, leaf traits, soil states and atmospheric CO2. The new model is calibrated to match the biophysical responses of a complex terrestrial ecosystem model (TEM) of GPP and ET through a Bayesian model-data fusion process. The calibrated ACM-GPP-ET generates unbiased estimates of TEM GPP and ET, and captures 80–95% percent of the sensitivity of carbon and water fluxes by the complex TEM. The ACM-GPP-ET model operates ∼2200 times faster than the complex TEM. Independent evaluation of ACM-GPP-ET at FLUXNET sites, using a single global parameterisation, shows good agreement with typical R20.60 for both GPP and ET. This intermediate complexity modelling approach allows full Monte Carlo based quantification of model parameter and structural uncertainties, global scale sensitivity analyses for these processes, and is fast enough for use within terrestrial ecosystem model-data fusion frameworks requiring large ensembles.

Thomas Luke Smallman and Mathew Williams
Interactive discussion
Status: open (until 07 Mar 2019)
Status: open (until 07 Mar 2019)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement
Thomas Luke Smallman and Mathew Williams
Model code and software

Aggregated Canopy Model for Gross Primary Productivity and Evapotranspiration (Version 1) T. L. Smallman and M. Williams https://doi.org/10.7488/ds/2480

Thomas Luke Smallman and Mathew Williams
Viewed  
Total article views: 124 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
96 24 4 124 2 5
  • HTML: 96
  • PDF: 24
  • XML: 4
  • Total: 124
  • BibTeX: 2
  • EndNote: 5
Views and downloads (calculated since 10 Jan 2019)
Cumulative views and downloads (calculated since 10 Jan 2019)
Viewed (geographical distribution)  
Total article views: 54 (including HTML, PDF, and XML) Thereof 54 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
No discussed metrics found.
Latest update: 15 Jan 2019
Publications Copernicus
Download
Short summary
Photosynthesis and evapotranspiration are processes with global significance for carbon and water cycling. Simulating these processes and their interactions has till now come at high computational cost. Here we present a new coupled model of intermediate complexity operating at orders of magnitude greater speed. Independent evaluation at FLUXNET sites for a single, global parameterization shows good agreement with typical R2 ~ 0.60.
Photosynthesis and evapotranspiration are processes with global significance for carbon and...
Citation
Share