The Measurements of Pollution in the Troposphere (MOPITT) instrument was launched on December 18th, 1999, onboard the NASA EOS-TERRA satellite. It is a nadir viewing infra-red radiometer which targets measurements of carbon monoxide (CO) and methane (CH4) using gas correlation spectroscopy to improve its spectral sensitivity. The CO profile measurements can exploit both up-welling thermal radiance in the 4.6 μm fundamental band and reflected solar radiance in the 2.3 μm band; CH4 column measurements are made at 2.2 μm. This project focuses on CO measurements from MOPITT and the development of an off-line retrieval algorithm which can be employed to determine the intrinsic accuracy of the system in particular regimes, such as profiles of pollution export regions relevant to Europe. This project was a new but essential activity in the TROPOSAT project supporting studies in a number of TROPOSAT activities including “Inverse modelling of satellite data using the IMAGE model”, “Tracing atmospheric pollution with satellite measurements”, “Validation of methane and carbon monoxide data from SCIAMACHY”, and “Satellite validation using ground-based spectroscopic techniques”.The basis of the study was the examination of the MOPITT CO profile data and their sensitivity to CO values at various altitudes through the troposphere. This sensitivity, as expressed through the averaging kernel, was examined via an off-line data inversion system (retrieval algorithm) and via the operational MOPITT retrieval system. The off-line scheme has been developed to allow the factors which influence the averaging kernel to be investigated for case situations. Results have shown that this scheme, currently implemented for the four MOPITT difference channels only, produces averaging kernels similar to those derived in the operational processor. Both systems demonstrate that averaging kernels are a necessary part of the interpretation of MOPITT data and are essential to comparisons of profiles from models/correlative observations.
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- Retrieval of CO Column and Profile Data from the MOPITT Instrument on EOS-TERRA
John J. Remedios
Nigel A.D. Richards
- Springer Berlin Heidelberg