Research

Research Interests
My principal research interest is to better understand the emissions of atmospheric constituents and their impact on climate, human health, and the economy. For that purpose, I use inverse optimization techniques combining real-air observations and atmospheric transport models.

Harvard-NASA Emissions Component (HEMCO)
I am the principal developer of HEMCO, a stand-alone software component for calculating emissions in global atmospheric models. HEMCO has been implemented in the GEOS-Chem chemical transport model and the NASA GEOS-5 general circulation model. Additional information about HEMCO can be found here. The HEMCO source code can be obtained from here.

Nitrogen oxide (NO) emissions calculated by the HEMCO standalone model
Nitrogen oxide (NO) emissions computed by the HEMCO standalone model for July 2014 and at horizontal resolution of 0.25 degrees. Emission calculations were based on the default GEOS-Chem emission settings. Meteorological input data required for calculation of lightning and soil NO emission were provided by the NASA Global Modeling and Assimilation Office. Click here for an animated version of the image (may take a little while to load).

On-line chemical data assimilation
Combining the HEMCO software framework with satellite data provides an opportunity to better constrain emissions in chemistry and climate models. I am currently implementing a data assimilation system for NOx into the NASA GEOS data assimilation system.

Emission inversion of organohalides
Emissions of organohalides – such as CHBr3, CH2Br2 or CH3I – constitute an important source of reactive halogen to the atmosphere. However, there still exist considerable uncertainties in the spatiotemporal distribution and magnitude of emissions of these compounds. I apply inverse modeling methods combining observed and model predicted atmospheric concentrations to better constrain organohalide emissions.

PhD (Empa)
In my PhD, I focused on the quantification of halogenated greenhouse gas emissions, using measurement data from the remote observaton sites Jungfraujoch (Switzerland), Mace Head (Ireland) and Monte Cimone (Italy) in combination with the Lagrangian particle dispersion model FLEXPART. By applying a Bayesian optimization technique, I estimated the European emissions of a wide range of (primarily man-made) halocarbons. I also performed a long-term measurement campaign in K-Puszta (Hungary), making it possible to obtain first detailed information on halocarbon emissions over Eastern Europe.
See here for more information on my PhD work.

 

Master thesis (ETH / CENICA) 
The subject of my master thesis was to investigate the impact of oil refinery emissions on air quality in Salamanca, Mexico. The study encompassed compounds of environmental concern (e.g. sulfur dioxide) as well as strongly odorous substances  such as organic compounds and hydrogen sulfide. More about air quality in Salamanca can be found here.