Validation and Improvement of Aerosol Retrieval Algorithms

Tropospheric aerosol particles form a major uncertainty in predicting climate change due to three main mechanisms. First there is the direct radiative forcing effect of the aerosols which occurs when radiation is scattered or absorbed by the aerosols. Next we have indirect radiative forcing which has its origin in the influence of the aerosols on cloud microphysics. And last, the presence of aerosols can modify the concentration of climate influencing constituents such as greenhouse gases trough heterogeneous chemistry.

Global observations from space are required due to short lifetime and a high spatial variability in aerosol optical and radiative properties.

The RMIB remote sensing group

One of the interests at the remote sensing group of the RMIB (KMI) is research, development, implementation and deployment of aerosol related algorithms. These are used to turn raw satellite images into images of a sufficient quality to be used by climate researchers and for (numerical) weather prediction. Most of this work is commissioned by and funded trough our international collaborations we are part of.

Most notably: the Satellite Application Facility on Climate Monitoring (CM-SAF) and Geostationary Earth Radiation Budget (GERB) collaborations.

Our group has a high quality IT infrastructure, this for both hardware and software. It is comparable to what most private companies have and/or require. All our core programming is done in C/C++ and we have an extensive in house built library for the treatment of images. All software is managed under subversion or git.

Aerosol Retrieval Algorithms

The retrieval of aerosol properties using satellites is a very intricate problem due to number of reasons:

  • The exact background which consists of ground and atmospheric properties is unknown but is observed using the same satellite imager (eye) resulting in an underdetermined system.
  • The concentration of aerosols is typically small. This means one is looking at small background values (aerosol properties) against a huge background (ground and atmospheric properties).
  • The exact type of the aerosols at a given location is unknown which adds the "aerosol composition" as an extra undetermined variable to each retrieval.
  • Aerosols are most easily observed using low wavelength channels (deep blue).  Newly launched research satellite imagers are equipped with at least one deep blue channel. However, all older generation satellites and most contemporary weather satellites do not have such luxury.

Themes for master thesis research work

What follows is an incomplete list of more specific topics that could be tackled by a masters student:

  • The influence of nearby clouds on satellite based aerosol retrieval
  • Validation and quality of aerosol products for climate research
  • Comparing thermal en solar retrieval of aerosol optical depth
  • Radiative forcing of aerosols in the thermal and solar spectrum
  • Combining satellite an ground measurements for higher resolution products
  • Active (lidar) versus passive (reflected sun light) remote sensing of aerosols

Additional information