PhD ceremony: R.O. Iannone, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen
Thesis: Development of a near-infrared optical feedback cavity enhanced absorption spectrometer (OF-CEAS) for atmospheric water vapor isotope ratio (18O/16O, 17O/16O, and 2H/1H) measurements
Promotor(s): prof.dr. H.A.J. Meijer, prof.dr.ir. E.R.T. Kerstel
Faculty: Mathematics and Natural Sciences
Contact: Rosario Iannone, tel. 00 39 479 104 076, e-mail: email@example.com
A novel near-infrared spectrometer was designed and built with the aim to measure in-situ the water deuterium and oxygen (17O and 18O) isotope ratios in the upper troposphere and lower stratosphere with a high temporal resolution (between 0.1 and 10 seconds, corresponding to a spatial resolution of roughly 20 meters to 2 km). The spectrometer is based on Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS).
The isotopic signature of stratospheric water is of great interest to the atmospheric physics community since it may be used to quantify troposphere-stratosphere exchange, as well as the water chemistry in the stratosphere. Close to the surface, instead, the isotopic composition of moisture is crucial in understanding the hydrological cycle and its link to the carbon cycle through the exchange of oxygen atoms in the ecosystem.
During the project, a new laboratory calibration system based on a piezo-nozzle injector (Microdrop GmbH) has been implemented. The micro-injector enables the production of moist air streams with a water mixing ratio ranging from 10 to 5000 ppm, representing the range of conditions expected in the lower stratosphere to the low troposphere.
Airborne operation of the spectrometer was demonstrated on the NASA DC-8 in May 2004 at NASA Dryden Flight Research Center, and later on the European M55-Geophysica stratospheric research aircraft, during the African Monsoon Multidisciplinary Analysis campaign in Burkina Faso in August 2006.
Finally, although the spectrometer was designed for use on high-altitude airborne platforms, it has also been applied to tropospheric moisture measurements.
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