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HyFLEX campaign 2012

– first data set of novel high-performance fluorescence sensor recorded

On Aug 20th the second component of the HyFlex campaign started in Western Germany (region between Bonn, Köln and Aachen). The aim of this campaign is to use for the first time a novel airborne sensor (HyPlant), which was developed by the Forschungszentrum Jülich and the finish company Specim. The HyPlant sensor is an imaging spectrometer that measures surface reflectance with high spectral resolution (0.25 nm between 680 and 780 nm). These data can be used to quantify the intensity of sun-induced fluorescence and data from this campaign should provide an experimental data pool to test the mission concept of FLEX earth explorer mission (currently in phase A).

Quantification of canopy fluorescence is still a challenge and thus researchers from nine European countries have gathered in this campaign and combined a wide array of instrumentation to measure sun-induced fluorescence from the level of single leaves to the airborne sensor, including a detailed characterization of the atmosphere.

The most challenging component of the campaign was the new airborne sensor, which provides an unpreceeded spectral resolution with high signal to noise ratio. The sensor was first tested in Finland and then shipped to Luxemburg for installation and certification. On Monday Aug 20th the sensor and all ground teams arrived in the campaign area and briefings and campaign preparations started. Despite the fact that a dense network of infrastructure ad to be installed all the teams worked efficiently and we could perform the first test measurements under reasonable weather conditions already on Wednesday (Aug 22nd). Most of the measurements worked fine and we could optimize the measurement protocol and decided for an ambitious measurement day on Thursday Aug 23rd.

Weather on Thursday 23rd was predicted to be ideal, however we experienced quite some high cumulus clouds in the morning hours. Nevertheless we decided to start the measurements as planned at 11am local time and our airplane started for am ambitious flight pattern consisting of 36 flight lines. Fortunately weather conditions improved and during solar noon we experienced almost perfect illumination conditions. Illumination remained good over the course of the day and we could record a potentially excellent data set of airborne data, which cover time series of various vegetation types.

Also ground teams worked in an exceptionally manner and we were able to record all necessary ground reference data. Ground data include automated time series of sun-induced fluorescence from three vegetation types (University of Milano, Forschungszentrum Jülich), top-of-canopy radiance and reflectance (Univ. Zurich, Forschungszentrum Jülich, Czech Globe, Univ. Valencia), detailed characterization of atmospheric aerosol profiles (Univ. Athens, Uni. Valencia, Czech Globe), maps of sun-induced fluorescence measured by quattrocopters (Univ. Trier), hyperthermal measurements (Lippmann Inst.) and several supportive vegetation measurements.

The last flight lines are recorded as this BLOG is written. However, I can already state that this was one of the best scientific experience I had in my life. It is simply fascinating how well and smoothly the expertise of the contributing groups merged to an orchestrated field campaign, which promises a novel experimental data set on sun induced fluorescence. I am looking forward to see the data to have the first quicklooks be delivered.

I would greatly want to thank all the teams and people, who contributed to this measurement day.

Uwe Rascher (PI and coordination of the HyFlex campaign 2012)