MyLake v. 1.12, used for the ISIMIP simulations, is a one-dimensional process-based lake model coded in Matlab whose initial release was developed in 2007 by Tuomo Saloranta and Tom Andersen at the Norwegian Institute of Water Research. It has a relatively simple and transparent model structure, it is easy to set up, and is suitable both for making predictions and scenarios, and to be used as an investigative tool. Short runtime allows applications of comprehensive sensitivity and uncertainty analysis as well as simulation of a large number of lakes or over long periods (decades). MyLake aims to include only the most significant physical, chemical and biological processes in a well-balanced and robust way (Saloranta & Andersen 2007).
The model is available as an open-source project via GitHub. Being an open source project, the MyLake code has been forked and adapted to suit a project’s needs. There are thus several existing branches, which are collected in a suite of repositories at github.com/biogeochemistry. Here we identify three versions of MyLake that are actively used or developed:
i) 1.12 refers to the Mylake model as it was first written by Saloranta and Andersen (2007). MyLake 1.12 is for the simulation of daily 1) vertical distribution of lake water temperature and thus stratification, 2) evolution of seasonal lake ice and snow cover, and 3) phosphorus-phytoplankton dynamics. It contains a simple sediment box-model. When only hydrodynamic and ice cover simulations are necessary, this version is recommended with sediment and phytoplankton modules turned off.
ii) Version 2.0 refers to the model with extended biogeochemical reaction network ( N, O, P, Mn, Fe, Al, Ca, Si, S, pH) and process-based sediment diagenesis with a focus on redox processes. It builds on version 1.12 and adds simulation of daily 1) distribution of geochemical species, 2) fluxes across the sediment-water interface, 3) vertical distribution of geochemical species in the sediment and porewater. For simulation focussing on oxygen dynamics, either the diagenetic module or a simpler fixed-k sediment oxygen demand module can be used.
iii) Version C refers to the model with extended gas exchange models for O, CO2 and CH4 with a focus on DOC cycling. It builds on version 1.12 and adds simulation of daily distribution of dissolved cases according to user-selectable gas exchange models.
