The document introduces STILT, a Lagrangian atmospheric transport model used to calculate carbon dioxide (CO2) footprints and sensitivities at ICOS atmospheric measurement stations. STILT runs are split into small jobs that are distributed across multiple virtual machines (VMs) in a cloud computing environment. While most components of the distributed STILT workflow have been tested, further work is needed to optimize the model code for parallel processing, initialize multiple worker VMs, address storage issues, and develop metadata and output visualization capabilities before the system can operate fully. A demonstration illustrates how a user could run STILT to model CO2 concentrations and contributing sources and sinks for a hypothetical station in Vienna.

1. IntroductiontoSTILT anon-demandCO– 2footprintcalculatorservice
UteKarstens,OlegMirzov,AndréBjärby,RogerGroth,MitchSelander,AlexVermeulen& Maggie
Hellström
ICOS Carbon Portal
& Lund University
EUDATconference,Porto23-24January,2018

2. IntegratedCarbonObservationSystem
This presentation by M. Hellström is CC BY 2
“A pan-European research infrastructure for
quantifying and understanding the
greenhouse gas balance of the European
continent”• Collect high-quality observational data relevant to
the greenhouse gas budget of Europe
• Promote the use of the ICOS data for further
scientific study
• Support modelling activities of the greenhouse gas
fluxes in time and space
• Support verification of the effectiveness of policies
aiming to reduce greenhouse gas emissions

3. Footprinttoolforatmosphericsites
This presentation by M. Hellström is CC BY 3
• Web-based service at ICOS Carbon Portal
• On-demand computation and visualization of
footprints and GHG concentrations at
atmospheric measurement stations
• Based on the Lagrangian atmospheric transport
model STILT
• Application examples:
o Analysis of the sensitivity of GHG concentration signals at
potential and existing ICOS atmospheric measurement
stations to GHG emissions and fluxes
o Evaluation of measurement strategies
o Network design studies
https://github.com/ICOS-Carbon-Portal/stiltweb
Use case for testing interoperability
between EGI and EUDAT services in
WP7/Task 7.2 of EUDAT2020

4. Footprintandsensitivity?!
This presentation by M. Hellström is CC BY 4
• As packets of air move over the Earth’s surface, their concentrations of CO2
will be influenced by the ground below. The surface area that influences the
air packet stream is the footprint.
• Areas with net CO2 uptake (“sinks”) will dilute the air packets’ CO2
concentration, while areas with net emissions (“sources”) will add to the air
packets’ CO2 content
• STILT makes it possible to estimate how well a measurement station can
track sources and sinks along the path of air packets that arrive to it. This is
the sensitivity.
atmosphere
station (ICOS)
air moving at >100
meters above the
surface

5. HowdoestheSTILTmodelwork?
5This presentation by M. Hellström is CC BY

6. TheSTILTworkflow-basic
This presentation by M. Hellström is CC BY 6

7. TheSTILTworkflow 2workernodes–
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demo!

8. TheSTILTworkflow fullyextended–
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9. Componentsoftheworkflow
This presentation by M. Hellström is CC BY 9
• Generic simulation
o Linux VMs in EGI Federated Cloud (fedcloud.egi.eu VO for testing)
o Scala for backend development, Akka Cluster for orchestration
o Docker-based version of model (or data processing tool)
• Storage
o B2SAFE long-term storage for ICOS measurement data and products
o Network File System for intermediate storage of model input/output
o EGI DataHub for storage of data from multiple providers (in future)
• STILT-specific components
o Split model runs into small jobs to allow distribution over many cores/VMs
o Handling of large numbers of small files (model output re-used as input)
o Prototype: 4 VMs of medium size (8 CPUs, 16-32 GB RAM) + 4 TB storage

10. Status&outlook
This presentation by M. Hellström is CC BY 10
Most parts of the workflow tested & working well, but there is still quite
some work to do before we have an operational setup:
• The STILT model code requires some further tweaking to optimize in
“parallelized” mode
• Initializing multiple worker VMs
• The datahub.egi.eu/OneData storage solution is still buggy
• Latest B2SAFE & B2STAGE (HTTP API) versions not yet tested &
incorporated
• Metadata creation & management yet to be done (for both model runs
and the output data)
• Downloading output not yet available & visualization tool is now very
basic; more functionality needed

11. Let’sseeashortdemo!
This presentation by M. Helölström is CC-BY 11
• This will illustrate how a Carbon Portal user would use the STILT on-
demand tool to calculate the CO2 footprint and sensitivity at a
hypothetical measurement station placed in Vienna.
• After the simulation is run, the user can visualize the geographical
areas contributing to the signal in Vienna, as well as see estimates of
how different processes (biological and human) contributed to the total
CO2 concentration.

12. Thanksforlistening!
This presentation by M. Helölström is CC-BY
Questions? Comments?
Please get in touch:
• Maggie Hellström (margareta.hellstrom@nateko.lu.se)
• Ute Karstens (ute.karstens@nateko.lu.se)
More information:
• ICOS ERIC website (https://icos-ri.eu/)
• ICOS Carbon Portal website (https://icos-cp.eu/)
• ICOS Carbon Portal’s STILTweb pages at GitHub (https://
github.com/ICOS-Carbon-Portal/stiltweb)
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