Skip to content

Commit

Permalink
More editing and trimming of text courtesy of M.J. Lara.
Browse files Browse the repository at this point in the history
  • Loading branch information
tobeycarman committed Sep 12, 2024
1 parent fda49a5 commit e911c9a
Showing 1 changed file with 40 additions and 51 deletions.
91 changes: 40 additions & 51 deletions joss-paper/paper.md
Original file line number Diff line number Diff line change
Expand Up @@ -147,9 +147,7 @@ bibliography: joss-paper.bib

The impacts of climate change on natural ecosystems are the result of complex
physical and ecological processes operating and interacting at a variety of
spatio-temporal scales. For this reason, process-based ecosystem models are
efficient tools to formalize and extrapolate our current understanding of
ecosystem dynamics and predict local, regional and global climate impacts.
spatio-temporal scales, that can be represented in process-based ecosystem models.

`DVMDOSTEM` is an advanced process-based terrestrial ecosystem model (TEM)
designed to study ecosystem responses to climate changes and disturbances. It
Expand All @@ -166,39 +164,37 @@ in permafrost, vegetation, and carbon (C) and nitrogen (N) dynamics.

Arctic and boreal regions underlain by permafrost store nearly half of the
world’s soil organic C - approximately 1,440-1,600 Pg [@Hugelius2014;
@Schuur2022]. These regions are warming roughly two to four times faster than
@Schuur2022]. These regions are warming four times faster than
the rest of the globe, driving widespread and rapid permafrost thaw
[@Rantanen2022; @Smith2022]. As permafrost thaws, soil organic C becomes
available for decomposition and release as greenhouse gasses (GHGs) to the
atmosphere. Climate-driven permafrost thaw and the associated release of GHGs
can influence the global climate system, a phenomenon called the permafrost
carbon-climate feedback or PCCF [@Koven2011; @Schuur2015]. The PCCF has been
identified as one of the largest sources of uncertainty in future climate
projections and therefore needs to be accurately represented in process-based
ecosystem models that inform global earth system models [@Schadel2024].

projections and therefore needs to be accurately represented in global earth
system models [@Schadel2024].

# Model Design

`DVMDOSTEM` is a process-based ecosystem model designed to simulate the key
`DVMDOSTEM` is designed to simulate the key
biophysical and biogeochemical processes between the soil, the vegetation and
the atmosphere. The evolution and refinement of `DVMDOSTEM` have been shaped by
extensive research programs and applications both in permafrost and
non-permafrost regions [@Genet2013; @Genet2018; @Jafarov2013; @Yi2010;
@Yi2009; @Euskirchen2022; @Briones2024]. The model is spatially explicit and
represents ecosystem response to climate and disturbances at seasonal (i.e.
monthly) up to centennial scales. The snow and soil columns are split into a
monthly) to centennial scales. The snow and soil columns are split into a
dynamic number of layers to represent their impact on thermal and hydrological
dynamics and the consequences for soil C and N dynamics. Vegetation composition
is modeled using community types (CMTs), each of which consists of multiple
plant functional types (PFTs - groups of species sharing similar ecological
traits). This structure allows the model to represent the effect of competition
for light, water and nutrients on vegetation composition [@Euskirchen2009]. The
model also represents the ecosystem N cycle to evaluate the role of nutrient
limitations, characteristic of permafrost regions, on ecosystem dynamics, with
coupling between the C and N cycles [@McGuire1992; @Euskirchen2009]. Finally,
for light, water and nutrients on vegetation composition [@Euskirchen2009], as well
as the role of nutrient limitation on permafrost ecosystem dynamics, with
coupling between C and N cycles [@McGuire1992; @Euskirchen2009]. Finally,
the model represents the effects of wildfire in order to evaluate the role of
climate-driven fire intensification on ecosystem structure and functions
climate-driven fire intensification on ecosystem structure and function
[@Yi2010; @Genet2013]. The structure of `DVMDOSTEM` is represented visually in
\autoref{fig:modeloverview}.

Expand Down Expand Up @@ -234,14 +230,14 @@ soil C stocks are a result of litterfall from the vegetation and decomposition
of soil C stocks by microbes (heterotrophic respiration or Rh). Changes in soil
organic and available N stocks are a result of litterfall, net mineralization of
organic N, and plant N uptake. Soil organic layers and soil C and N stocks may
also be modified as a result of wildfire.
also be modified due to wildfire.


## Vegetation structure and processes

Each vegetation CMT (e.g. “wet-sedge tundra”, “white spruce forest”, etc.), is
modeled with up to ten PFTs (e.g., “deciduous shrubs”, “sedges”, “mosses”,
etc.), each of which may have up to three compartments: leaf, stem, and root.
modeled with up to ten PFTs (e.g., “deciduous shrubs”, “sedges”, “mosses”),
each of which may have up to three compartments: leaf, stem, and root.
Vegetation C and N fluxes are calculated at each time step based on
environmental factors and soil properties. Assimilation of atmospheric $CO_2$ by
the vegetation is estimated by computing gross primary productivity (GPP) for
Expand All @@ -257,16 +253,14 @@ also be modified as a result of wildfire burn.

## Run stages

To initialize an historical or future simulation, `DVMDOSTEM` needs to compute a
To initialize historical or future simulations, `DVMDOSTEM` needs to compute a
quasi steady-state (QSS) solution. This solution is forced by using averaged
historical atmospheric and ecosystem properties (e.g. soil texture) to drive the
model. QSS of physical processes (e.g. soil temperature and water content) are
usually achieved in less than 100 years, while QSS of biogeochemical processes
(e.g. soil and vegetation C and N stocks) are achieved in 1,000 to >10,000
years. Additionally, biogeochemical QSS is achieved more rapidly if computed
starting with QSS soil physical properties. To leverage this property for
decreasing overall run-times, `DVMDOSTEM` uses two QSS stages: “Pre-run” and
“Equilibrium”. The list of all `DVMDOSTEM` run stages is as follows:
years. However, to decrease overall run-times, `DVMDOSTEM` uses two QSS stages:
“Pre-run” and “Equilibrium”. The list of all `DVMDOSTEM` run stages is as follows:

* Pre-run (pr): QSS computation for the physical state variables.
* Equilibrium (eq): QSS computation for the biogeochemical state variables.
Expand All @@ -275,18 +269,16 @@ decreasing overall run-times, `DVMDOSTEM` uses two QSS stages: “Pre-run” and
* Transient (tr): historical simulation.
* Scenario (sc): future simulation.

A complete model simulation requires advancing the model consecutively through
all of the run stages, however users are able to selectively skip stages as
needed to reduce compute time.

Model simulation requires advancing the model consecutively through
all of the run stages as needed (pr-eq-sp-tr).

## Spatial considerations

`DVMDOSTEM` can be applied at the site level or across large regions. Spatially,
`DVMDOSTEM` breaks up the landscape domain into grid cells, each of which is
characterized by a set of input (forcing) values and a set of parameterization
values. Parameterization values for a grid cell describe soil and vegetation
characteristics and are associated with a CMT. `DMVDOSTEM` does not include the
`DVMDOSTEM` breaks up the landscape into grid cells, each of which is
characterized by a set of input forcing and parameterization
values. Gridded parameterization values describe soil and vegetation
characteristics associated with each CMT. `DVMDOSTEM` does not include the
lateral transfer of information between grid cells. The CMT classification for
each grid cell is static across the time dimension of a model simulation. These
two factors limit the ability of the model to represent climate-driven biome
Expand All @@ -297,9 +289,9 @@ capabilities to `DVMDOSTEM`.

## Inputs and outputs

`DVMDOSTEM` inputs and outputs are NetCDF files [@Rew1990], which conform
NetCDF files [@Rew1990] are used as model inputs and outputs, conforming
to the CF Conventions v1.11 [@Eaton2011] where possible. The input variables
used to drive `DVMDOSTEM` are: drainage classification (upland or lowland), CMT
used to drive `DVMDOSTEM` include: drainage classification (upland or lowland), CMT
classification, topography (slope, aspect, elevation), soil texture (percent
sand, silt, and clay), climate (air temperature, precipitation, vapor pressure,
incoming shortwave radiation), atmospheric $CO_2$ concentration, and fire
Expand All @@ -315,8 +307,8 @@ computational resources and information needs when setting up a model run.

# Parameterization

`DVMDOSTEM` parameterization sets are developed for each CMT represented in the
model. Each CMT is defined by more than 200 parameters. Parameter values are
`DVMDOSTEM` parameterization sets are developed for each CMT. Each CMT is defined
by more than 200 parameters. Parameter values are
estimated directly from field, lab or remote sensing observations, literature
review or site-specific calibration. Calibration is required when (1) parameter
values cannot be determined directly from available data or published
Expand All @@ -326,7 +318,7 @@ acceptable agreement between measured field data and model prediction on the
state variables most influenced by the parameter to be calibrated. Due to the
large number of parameters requiring calibration, and the non-linear nature of
the relationships between parameters and state variables, model calibration can
be a labor intensive process. We are actively developing a calibration process
be labor-intensive. We are actively developing a calibration process
that allows automation [@JafarovINPREP2024].


Expand All @@ -335,16 +327,15 @@ that allows automation [@JafarovINPREP2024].
The `DVMDOSTEM` software repository is a combination of tightly coupled
sub-components:

- the `DVMDOSTEM` model itself,
- the `DVMDOSTEM` model,
- supporting tools, and
- development environment specifications.

The core of the project is the `DVMDOSTEM` model. The `DVMDOSTEM` model
is written in C++ and uses some object-oriented concepts. The model exposes a
command line interface that allows users to start simulations manually or
use a scripting language to drive the command line interface.
The core `DVMDOSTEM` model is written in C++ and uses some object-oriented concepts.
The model exposes a command line interface that allows users to start simulations
manually or use a scripting language to drive the command line interface.

Surrounding the core model is a large body of supporting tooling to assist the
Surrounding the core model is a large body of supporting tools to assist the
user with preparing inputs, setting up and monitoring model runs and analyzing
model outputs. This collection of tools is primarily written in Python and shell
scripts, with some of the demonstration and exploratory analysis using Jupyter
Expand All @@ -354,16 +345,14 @@ interfaces and a Python API which are documented in the User Guide.
The model and tools target a UNIX-like operating system environment. The
combination of the core `DVMDOSTEM` model and the supporting tools result in the
need for a complex computing environment with many dependencies. Docker images
are used to manage this complexity, providing consistent environments for
development and production, [@Merkel2014]. The project includes the
specification for development images as well as a pared down runtime-only image.

The software design is a work in progress stemming from the organic growth
spanning 30+ years of development by research scientists, graduate students and
programmers. Recent years have seen an increased effort to apply professional
software development practices such as version control, automated documentation,
containerization, and testing.

are used to manage this complexity, providing consistent environments
for development and production, [@Merkel2014].

Software updates are ongoing, stemming from the organic growth spanning 30+ years
of development by research scientists, graduate students and programmers. Recent
years have seen an increased effort to apply professional software development
practices such as version control, automated documentation, containerization,
and testing.

# Acknowledgements

Expand Down

0 comments on commit e911c9a

Please sign in to comment.