B43H-0644
PhotoSpec - Ground-based Remote Sensing of Solar-Induced Chlorophyll Fluorescence

Thursday, 17 December 2015
Poster Hall (Moscone South)
Katja Grossmann1,2, Christian Frankenberg3, Ulrike Seibt2, Stephen C Hurlock1,2, Alexandria Pivovaroff4 and Jochen Stutz1,2, (1)University of California Los Angeles, Joint Institute For Regional Earth System Science and Engineering (JIFRESSE), Los Angeles, CA, United States, (2)University of California Los Angeles, Department of Atmospheric and Oceanic Sciences, Los Angeles, CA, United States, (3)NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States, (4)University of California Los Angeles, La Kretz Center for California Conservation Science, Los Angeles, CA, United States
Abstract:
Solar-Induced Chlorophyll Fluorescence (SIF) emitted from vegetation can be used as a constraint for photosynthetic activity and is now observable on a global scale from space. However, many issues on a leaf-to-canopy scale remain poorly understood, such as influences on the SIF signal of environmental conditions, water stress, or radiation.

Here, we report on the development and characterization of a novel ground-based spectrometer system for measuring SIF from natural ecosystems (http://www.kiss.caltech.edu/study/photosynthesis/technology.html). The instrumental set-up, requirements, and measurement technique are based on decades of experience using Differential Optical Absorption Spectroscopy (DOAS), an established method to measure atmospheric trace gases. The instrument consists of three thermally stabilized commercial spectrometers that are linked to a 2D scanning telescope unit via optical fiber bundles. The spectrometers cover an SIF retrieval wavelength range at high spectral resolution (670 - 780 nm, 0.1 nm FWHM), but also provide moderate resolution spectra (400 - 800 nm, 1.5 nm FWHM) in order to retrieve vegetation indices and the photochemical reflectance index (PRI).

In addition to the instrumental set-up, we will show initial results of test and field measurements with the new instrument that examine the diurnal cycle of the SIF signal of different California native and non-native plants and its correlation with CO2 fluxes. Observations were made under different environmental conditions, variable water and nutrient stress, and with different viewing geometries. We also used concurrent observations by a photosynthetically active radiation (PAR) sensor and a portable chlorophyll fluorometer (PAM) to link the SIF signal to plant metabolism and carbon cycling under a range of environmental conditions.

<< Previous Abstract | Next Abstract >>