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Research Projects

Climate stress impacts on forest emissions and aerosol pollution (ClimStress)

Terrestrial plants emit 80% of the organic gases into the atmosphere that drive the chemical formation of hazardous air pollutants. These gases rapidly oxidize, leading to the formation of ozone and particles, which pose risks for human health and impact Earth’s climate by acting as greenhouse gases, scattering light, or serving as cloud condensation nuclei.

The increased frequency and intensity of drought, heat, and herbivory stress caused by global warming stresses plants, changing the composition and amount of gases they emit. However, the overall direction of this change and the resulting impact of stressed forest emissions on the Earth’s atmosphere is unknown. Significant knowledge gaps include the effects of combined stressors and of stress impacts at the real-world ecosystem scale on emissions and oxidation products. This current state of knowledge, mainly based on limited laboratory investigations, makes it virtually impossible to predict impacts of plant stress on air quality and climate.

 

 

 

 

 

 

 

 

 

 

 

 

How will plant emissions impact future air quality under climate change while the switch to renewable energy reduces anthropogenic emissions? The project “ClimStress” addresses this question by a unique combination of chamber and field measurements with novel instrumentation that can characterize gases and particles in unprecedented comprehensiveness. Linking a plant chamber with a state-of-the-art atmospheric oxidation chamber, we will investigate how combinations of multiple stressors impact tree emissions and their atmospheric oxidation towards air pollutants. The first airborne emission measurements on board a Zeppelin airship will enable us to quantify ecosystem-scale emissions along a gradient of stressed towards less-stressed forest. Thus, "ClimStress" will provide crucial input for accurate modelling of atmospheric chemistry and air quality, and thereby help reduce the uncertainty in future air pollution and climate predictions.

Plant Chamber measurements in SAPHIR-PLUS

SAPHIR-PLUS is a plant chamber coupled to the large atmospheric oxidation chamber SAPHIR at Forschungszentrum Jülich. It provides a controlled environment for up to six trees. The oxidation processes of the tree emissions can be observed in SAPHIR.

Zeppelin-based airborne flux measurements

A Zeppelin is an ideal platform for tropospheric chemistry research, as it can fly low and slowly. These abilities also make it highly useful for airborne eddy covariance flux measurements, i.e. direct emission measurements.

Past Projects

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Reevaluating Chemistry of the Atmosphere in California (RECAP-CA) 2021

What are the most relevant sources of secondary air pollution? We found that temeprature-dependent emissions dominate air pollution potential in Los Angeles, and were able to identify gaps in emission inventories. In the agricultural San Joaquin Valley, we found that dairy and citrus emissions are underestimated by current models.

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Air Quality and Climate Change in the Arabian Basin (AQABA) 2017

The Middle East is an understudied hotspot of ozone and particle pollution. We found air as polluted as in megacities in the middle of the Persian Gulf -due to shipping and oil/gas extraction.

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Amazon Tall Tower Observatory (ATTO)

2016-2019

Intercomparison of OH reactivity measurements (kOHComp) 2015-16

At the ATTO site, atmospheric scientists from Brazil and Germany study the chemistry of a pristine atmosphere. Here, I led studies on the impact of drought and heat on atmospheric reactivity, and on the total OH reactivity budget up to 320 m altitude

Direct measurements of OH reactivity, the total load of reactive trace gases, are relatively recent. Among ten different research groups from all over the world, I participated in the first comprehensive intercomparison campaign of all available methods.

Side projects / Collaborations

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