Research Activities

Introduction

The chemistry of the Troposphere (the lowest 10km of the atmosphere) is driven by radicals species, for example OH, NO3, BrO, IO,.... These species are responsible for the selfcleaning capacity of the atmosphere, slowly oxidising and removing hydrocarbons, nitrogen oxides, etc. Many of these compounds also have a direct influence on the concentration of ozone. The OH radical for example is involved in the formation of "photochemical smog", one of the major problems in polluted areas. BrO is responsible for the total destruction of ozone in the polar boundary layer (the lowest part of the tropopshere) during spring.

The knowledge of the concentration and chemistry of these species and their precursors is essential for the understanding of our atmosphere. Three different approaches are used today to study atmospheric chemistry:

Only the interaction of all three approaches gives enough information to understand the complicated nature of our atmosphere.

My main focus is on the first of these three topics: The observation of chemical species, especially radicals and their precursors, in the open atmosphere by spectroscopic techniques.

The following list gives an overview over the different research topics I am intersted in. Please Click on the titles to jump to more extensive information

DOAS

The Differential Optical Aborption Spectroscopy (DOAS) is a method to measure very reactive trace gases without disturbing the actual composition of the atmosphere. It is especially useful for radical species. For a DOAS measurement a parallel light beam is sent through the atmosphere. After a path of up to several kilomters the spectrum of the light is analysed. Trace gases like NO2, ozone, BrO, NO3 , and many others change this spectrum in a characteristic which is the used to calculate the concentrations of these gases. To learn more about DOAS click here .

Nitrous Acid (HONO) and its Influences on Photosmog

 One of the least understood precursors of the OH radical is nitrous acid. HONO is photolysed during the day producing OH which then participates in the formation of ozone. The chemistry of HONO in the atmosphere is not well understood today. For example the possible sources of HONO are not well known at the moment. It is also unclear how important HONO is as a OH source. Field study can help to answer the gaps in our understanding of HONO chemistry. To learn more about HONO click here .

Nightime chemistry: The nitrate radical (NO3)

The nitrate radical NO3 is the most important radical species during the night. Knowledge of its concentration is essential for the understanding of night-time chemistry, one of the focus areas of current research. To learn more about NO3 click here

The Influence of Halogen Oxides (ClO, BrO, IO) on Tropospheric Ozone Chemistry

Only recently it has been recognized that halogen oxides can also play an important role in the troposphere. Our recent discovery of elevated concentrations of BrO and IO in the mid-latitude boundary layer triggered a discussion about the importance of reactive halogen species for ozone chemistry. To learn more about halogen oxides click here

Field Campaigns

If you want to learn what we are doing in the field here is some information (at the moment only links) on the different field campaign I have participated lately: