Potential of the geostationary GeoCarb mission to estimate surface emissions of CO2, CH4 and CO in a polluted urban environment
- Paper number
IAC-17,B1,2,9,x39507
- Author
Dr. DENIS O'BRIEN, Australia
- Coauthor
Dr. Igor Polonsky, AER, United States
- Coauthor
Dr. Steven Utembe, Melbourne University, Australia
- Coauthor
Prof. Peter Rayner, Melbourne University, Australia
- Coauthor
Mr. Andrew Clark, Australia
- Year
2017
- Abstract
In December 2016 NASA competitively selected GeoCarb as an Earth Venture mission. GeoCarb will measure plant health and stress, and will probe, in unprecedented detail, sources, sinks and exchange processes that control CO$_2$, CH$_4$ and CO in the atmosphere. GeoCarb will be placed in geostationary orbit over the Americas to measure spectra of reflected sunlight in absorption bands of CO$_2$, CH$_4$, CO and O$_2$. Plant stress will be inferred from solar-induced fluorescence, using observation in Fraunhofer lines within the O$_2$ band. Column-averaged concentrations of CO$_2$, CH$_4$ and CO will be derived from all bands simultaneously. GeoCarb will scan the hemisphere in its field of view at least twice per day with spatial resolution of approximately 5 km. Thus, GeoCarb will provide concentration maps at unprecedented spatial and temporal resolution. In addition, GeoCarb can be commanded in flight to scan selected targets multiple times per day in order to capture diurnal cycles. Such detailed observations will allow the emissions of large cities to be estimated directly, thereby providing a new and important source of data for monitoring compliance with emission treaties. To demonstrate the latter capability, detailed numerical models were used to simulate the polluted atmosphere over selected large, industrial cities. Next spectra of radiation reflected to space in the bands of GeoCarb were computed, and then deliberately corrupted with noise at the level predicted for GeoCarb. Finally, the pseudo-observations were inverted to recover (1) the time-varying fields of CO$_2$, CH$_4$ and CO and (2) the time-varying sources of these gases within the city. This paper presents a selection of results from these simulations, highlighting the accuracy with which gas concentrations and source strengths can be recovered.
- Abstract document
- Manuscript document
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