Compact Solar Spectroscopic Column CO2, CH4, H2O and HOD Observations: Performance Evaluation at TCCON Sites
Thursday, 18 December 2014
Monitoring, reporting and verification (MRV) of natural sources and sinks and anthropogenic emission of carbon dioxide (CO2) and methane (CH4) are crucial to predict climate change and develop transparent accounting policies to contain climate forcing. Remote sensing technologies are beginning to monitor CO2 and CH4 from ground and space (OCO-2 and GOSAT) with solar spectroscopy enabling direct MRV. However, current ground based coverage is sparse due to the need for large and expensive high-resolution spectrometers that are part of the Total Column Carbon Observing Network (TCCON, Bruker 125HR). This limits our MRV and satellite validation abilities, both regionally and globally. There are striking monitoring gaps in Asia, South America and Africa where the CO2 emissions are growing and there is a large uncertainty in fluxes from land use change, biomass burning and rainforest vulnerability. To fill this gap we evaluate the precision, accuracy and stability of our new compact, affordable and easy to use low-resolution spectrometer (Bruker EM27SUN) by comparing it with the much larger high-resolution TCCON instruments for column CO2, CH4, H2O and HOD. Results from Four Corners, Los Alamos, Caltech and Dryden-Armstrong sites show that our EM27SUN captures the variability of the aforementioned constituents very well, but has low and high offsets for CO2 and CH4, respectively. These off-the-shelf spectrometers should dramatically expand the coverage of regional column CO2 and CH4 observations, particularly in gap regions that include the rainforest. We will present opportunities that we are exploring to help enable transparent and reliable MRV and measurement of the coupled water-carbon cycle in tropical ecosystems.