# Jan Clemens (@jan-clemens.eurosky.social)

Profile: https://sifa.id/p/jan-clemens.eurosky.social
Headline: Simulation & Data Scientist | Earth System Science

## Career

- **PostDoc - Software Engineering & Data Analysis at Forschungszentrum Jülich** (Dec 2023 - Present)
  Full-time
- **MSc Candidate - Software Engineering & Data Analysis at Forschungszentrum Jülich** (Jan 2020 - Dec 2023)
  Part-time
- **PhD Candidate - Software Engineering & Data Analysis at Forschungszentrum Jülich** (Jan 2020 - Dec 2023)
  Full-time · Hybrid
- **Software Engineering & Data Analysis at University of Wuppertal** (Jan 2018 - Dec 2018)
  Part-time · On-site

## Skills

### Technical
- C
- C++
- Python

## Projects

- **WarmWorld** — https://www.warmworld.de/better/ (Dec 2023 - Present)
  WarmWorld is a German climate research project bringing together several major research institutions to improve ICON, a global climate model, so it can make sharper, more local climate predictions and better forecast extreme weather. The goal is to shrink the model's resolution down to just 1–5 km, much finer than today's typical models, which requires making the model faster, more precise, and easier to use. It's funded by the German government (BMFTR) and led by experts from institutions including the Max Planck Institute for Meteorology, the Alfred Wegener Institute, the German Climate Computing Center, and the University of Cologne. My contribution focused on integrating our own chemistry transport model into ICON as a plugin, enabling high resolution simulation of how gases and particles move through the atmosphere at the finer scales targeted by the project.
- **PHILEAS - Probing High Latitude Export of Air from the Asian Summer Monsoon** — https://journals.ametsoc.org/view/journals/bams/107/7/BAMS-D-24-0232.1.xml (May 2023 - Aug 2023)
  This project studied how the Asian summer monsoon connects the near-surface atmosphere over Southeast Asia to the upper atmosphere on a global scale, through a large international research collaboration. We found that the monsoon acts as a major pathway, lifting moisture, aerosols, and pollutants up into the high atmosphere and out toward the poles. This affects atmospheric chemistry, including the breakdown of stratospheric ozone, and changes how the atmosphere absorbs and reflects radiation, which matters for climate. Long-range transport of aerosols like ammonium nitrate can also influence cloud formation, adding another way this process shapes weather and climate. My contribution included climatological analysis ahead of the field campaign to help identify promising measurement locations, and during the campaign, working closely with the measurement team to analyze near-real-time model simulations of the relevant atmospheric processes. I also supported flight planning using PLANET and MSS, a tool set that displays the aircraft's flight path on a map with additional data overlays.
- **GRIPS (GRound-based Infrared P-branch Spectrometer)** — https://iau.uni-wuppertal.de/en/research/atmospheric-physics/infrared-remote-sensing/grips/overview/ (Jan 2018 - Jan 2019)
  GRIPS is a long-term measurement project at the University of Wuppertal that tracks the temperature of the atmosphere at around 87 km altitude, using ground-based infrared spectrometers to observe natural airglow emissions at night. The project has been running continuously since 1987, making it one of the longest-running datasets of its kind, and contributes to an international network monitoring this atmospheric region. I worked on the software that processes the raw measurements into temperature data, maintaining and improving it, integrating a spectra simulation tool into the workflow, and analyzed the resulting temperature data to check for and understand possible systematic errors.

## Publications

- MPTRAC: Domain-decomposed Massively-Parallel Trajectory Calculations (Mar 2026) https://doi.org/10.5194/egusphere-egu26-10878
- MPTRAC: A high-performance Lagrangian transport model for atmospheric air parcel dispersion — Journal of Open Source Software (Jul 2025) https://doi.org/10.21105/joss.08177
- Variability and trends in the PV-gradient dynamical tropopause (Jan 2025) https://doi.org/10.5194/egusphere-egu24-10991
- Variability and trends in the potential vorticity (PV)-gradient dynamical tropopause — Atmospheric Chemistry and Physics (Dec 2024) https://doi.org/10.5194/acp-24-13653-2024
- Implementation and evaluation of diabatic advection in the Lagrangian transport model MPTRAC 2.6 — Geoscientific Model Development (May 2024) https://doi.org/10.5194/gmd-17-4467-2024
- Accelerating Lagrangian transport simulations on graphics processing units: performance optimizations of Massive-Parallel Trajectory Calculations (MPTRAC) v2.6 — Geoscientific Model Development (May 2024) https://doi.org/10.5194/gmd-17-4077-2024
- Variability and trends in the PV-gradient dynamical tropopause (Feb 2024) https://doi.org/10.5194/egusphere-2024-471
- A multi-scenario Lagrangian trajectory analysis to identify source regions of the Asian tropopause aerosol layer on the Indian subcontinent in August 2016 — Atmospheric Chemistry and Physics (Jan 2024) https://doi.org/10.5194/acp-24-763-2024
- Evaluation of vertical transport in ERA5 and ERA-Interim reanalysis using high-altitude aircraft measurements in the Asian summer monsoon 2017 — Atmospheric Chemistry and Physics (Jan 2024) https://doi.org/10.5194/acp-24-317-2024
- Accelerating Lagrangian transport simulations on graphics processing units: performance optimizations of MPTRAC v2.6 (Jan 2024) https://doi.org/10.5194/egusphere-2023-2547
- Implementation and evaluation of diabatic advection in the Lagrangian transport model MPTRAC 2.6 (Nov 2023) https://doi.org/10.5194/gmd-2023-214
- Lagrangian transport simulations using the extreme convection parameterization: an assessment for the ECMWF reanalyses — Atmospheric Chemistry and Physics (Jul 2023) https://doi.org/10.5194/acp-23-7589-2023
- Evaluation of vertical transport in the Asian monsoon 2017 from CO2 reconstruction in the ERA5 and ERA-Interim reanalysis (Jun 2023) https://doi.org/10.5194/egusphere-2023-1026
- Identification of source regions of the Asian Tropopause Aerosol Layer on the Indian subcontinent in August 2 (May 2023) https://doi.org/10.5194/egusphere-egu23-2709
- Identification of source regions of the Asian Tropopause Aerosol Layer on the Indian subcontinent in August 2016 (Apr 2023) https://doi.org/10.5194/egusphere-2022-1462
- Lagrangian transport simulations using the extreme convection parametrization: an assessment for the ECMWF reanalyses (Feb 2023) https://doi.org/10.5194/egusphere-2023-72
- Massive-Parallel Trajectory Calculations version 2.2 (MPTRAC-2.2): Lagrangian transport simulations on graphics processing units (GPUs) — Geoscientific Model Development (Apr 2022) https://doi.org/10.5194/gmd-15-2731-2022
- Characterization of transport from the Asian summer monsoon anticyclone into the UTLS via shedding of low-potential vorticity cutoffs (Mar 2022) https://doi.org/10.5194/egusphere-egu22-1443
- Characterization of transport from the Asian summer monsoon anticyclone into the UTLS via shedding of low potential vorticity cutoffs — Atmospheric Chemistry and Physics (Mar 2022) https://doi.org/10.5194/acp-22-3841-2022
- Massive-Parallel Trajectory Calculations version 2.2 (MPTRAC-2.2): Lagrangian transport simulations on Graphics Processing Units (GPUs) (Dec 2021) https://doi.org/10.5194/gmd-2021-382
- Supplementary material to "Massive-Parallel Trajectory Calculations version 2.2 (MPTRAC-2.2): Lagrangian transport simulations on Graphics Processing Units (GPUs)" (Dec 2021) https://doi.org/10.5194/gmd-2021-382-supplement
- Characterization of transport from the Asian summer monsoon anticyclone into the UTLS via shedding of low-potential vorticity cutoffs (Nov 2021) https://doi.org/10.5194/acp-2021-905

## Education

- **University of Wuppertal** — PhD, Physics (Jan 2020 - Jun 2024)
- **University of Wuppertal** — MSc, Physics (Apr 2018 - Oct 2020)
- **University of Wuppertal** — BSc, Physics (Oct 2014 - Mar 2018)

## Awards

- Code of the Month — JuRSE (Mar 2025)
  Each month JuRSE highlights a code from Forschungszentrum Jülich and this month's code is developed at the Institute for Advanced Simulation, Jülich Supercomputing Centre (JSC).
  
  Massive-Parallel Trajectory Calculations (MPTRAC) is a Lagrangian particle dispersion model for the analysis of atmospheric transport processes in the free troposphere and stratosphere.

## Languages

- German (native)
- English (full professional)
- Chinese (elementary)

## Links

- Codeberg: https://codeberg.org/janhclem
- GitHub: https://github.com/janhclem (verified)
- ORCID: https://orcid.org/0000-0002-2422-9454 (verified)
- Research Gate: https://www.researchgate.net/profile/Jan_Clemens2?ev=hdr_xprf
- LinkedIn: https://www.linkedin.com/in/jan-heinrich-clemens-759a6b3b5/