Air pollution and greenhouse gas maps

We develop algorithms to retrieve NO2 and CH4 maps from the spectral radiance information provided by airborne and satellite imagers. The maps are used to characterize air pollutants and greenhouse gases and to obtain detailed information on individual emission sources. Our activities enable environmental monitoring at the scale of cities using remote sensing techniques to support policy makers and as a critical input for epidemiological studies.

Retrieval algorithms

We develop algorithms for the retrieval of NO2 and CH4 from airborne imaging spectrometers using differential optical absorption spectroscopy (DOAS). For this purpose, we have developed the flexDOAS library, which is an open-source Python package for DOAS analyses. The code is available on our GitLab page: https://gitlab.com/empa503/remote-sensing/flexdoas.
High-resolution air pollution mapping
The Sentinel-5P/TROPOMI satellite instruments measures NO2 maps at 6 km resolution, which is already quite high but still coarser than the required 1 km resolution. We develop machine learning algorithm that downscale TROPOMI NO2 observations. Our algorithm creates hourly maps of griddied near-surface NO2 concentrations at 100 m resolution. The model was trained with in situ NO2 ground measurements to predict NO2 concentrations using NO2 satellite images, land use data, meteorological fields and topographical information. The maps can be used as input for air pollution control and epidemiological studies.

PD Dr. Gerrit Kuhlmann
Senior Scientist

Phone: +41 58 765 4753

Publications
  • Kuhlmann et al. (2022): Mapping the spatial distribution of NO2 with in situ and remote sensing instruments during the Munich NO2 imaging campaign. Atmos. Meas. Tech., doi: https://doi.org/10.5194/amt-15-1609-2022.
  • Kim et al. (2021): Importance of satellite observations for high-resolution mapping of near-surface NO2 by machine learning. Remote Sens. Environ., doi: https://doi.org/10.1016/j.rse.2021.112573.
  • Kuhlmann et al. (2016): An algorithm for in-flight spectral calibration of imaging spectrometers. Remote Sens., doi: https://doi.org/10.3390/rs8121017.