A modern, modular and extensible framework
for large scale glacier modeling


Tutorial IGE 2021
These slides are available online at oggm.org/tutorial_talk

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Goals of today's talk

  • (Re-)brand OGGM as a modelling framework in which you can fit your own model and ideas
  • Showcase some of OGGM's applications
  • List some challenges the project is facing ...
  • ... and discuss ways forward

Today's Non-goals

  • "Selling" OGGM: other models out there are better in many aspects, and model diversity is the motto that drives our project (if anything, we'd rather try to convince you to contribute to it)
  • Traditional unidirectional talk:
    please interrupt me anytime

Motivation

GlacierMIP consortium (Marzeion et al., 2020)

Data

Data availability / quality for the 200k of the world's glaciers is low (this is changing very fast, but there is some adoption latency on the model side)

Uncertainty

  • GlacierMIP model spread shows that the individual models' uncertainty estimates are too low.
  • Difficulties to agree on experimental protocols within GlacierMIP leads to apples and oranges comparisons

More physics is always better, right?


Little reflection (so far) in the global glacier modelling community about which processes are adding value and which are adding noise.

OGGM

  • Modelling framework facilitating the modelling of many glaciers
  • Open source, using modern scientific python
  • Community driven ecosystem (at least we try)
  • Welcoming and flexible

The OGGM workflow

"Glacier centric" approach

Local grid and DEM

Centerlines

Flowlines and widths

Mass-balance & ice thickness

Glacier evolution

Workflow in practice

Glacier directories


Persistent data containers on disk

Entity tasks


Actions to perform on a glacier directory
CC BY-SA 3.0 Wikimedia

Global tasks


Actions to perform on many glaciers

In code


# Go - initialize glacier directories
gdirs = workflow.init_glacier_directories(rgidf)

task_list = [
    tasks.define_glacier_region,
    tasks.glacier_masks,
    tasks.compute_centerlines,
    tasks.catchment_area,
    tasks.catchment_width_geom,
]
for task in task_list:
    execute_entity_task(task, gdirs)

Strategies for modularity


(beta version)

Example: the RGI-TOPO dataset


See the rgitools documentation

Example: ITS_LIVE 

gdir = init_glacier_directories(['RGI60-01.10689'])[0]

from oggm.shop import its_live, dems
dems.select_dem(gdir, dem_source='COPDEM')
tasks.glacier_masks(gdir)
its_live.vel_to_gdir(gdir)

Reproducible science


See our documentation

Some current and future projects based on OGGM

Some applications

Farinotti et al. 2019
Eis et al. 2021
Millenial simulations

edu.oggm.org

+ some other things

  • decalal projections
  • regional ice thickness estimates
  • RGI v7
  • PyGEM collaboration

Some developments

Frontal ablation playground

Loads of simulations

More simulations

#Buzzwords

data assimilation, bayes, ensemble approaches

Challenges

  • Technical debt
  • Expectations of new users vs reality
  • Entry level for new contributors is high
  • Maintenance work relying on too few scientists
  • Funding of incremental improvements is difficult

Discussion

  • Future of the flowline?
  • SMB models and uncertainty in precipitation / accumulation
  • How much complexity is just right?
  • Publish or perish (or: how do the others publish so much?)

Take home

  • OGGM is a modelling framework:
    cherry picking is encouraged!
  • your own fantastic model or game changing idea might fit into the framework: get in touch with us!
  • check out oggm.org and edu.oggm.org,
    and help us to make it even better!

Agenda for the rest of the day

Let's run oggm on the cloud! hub.oggm.org

If you want to play, please let me know in the chat during the coffee break so that I can create an account for you on OGGM-Hub