Precision validation of MIPAS-ENVISAT products
European Space Agency, (Special Publication) ESA SP (2007)
Abstract:
This paper discusses the variation and validation of the precision (defined as the dispersion of an ensemble of retrievals obtained from measurements of the same atmospheric state) of the ESA L2 products from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). The MIPAS L2 products contain estimates of random error derived from the propagation of the radiometric noise through the retrieval. The noise itself varies with time, steadily rising between decontamination events, but its contribution to the L2 random error also depends on the atmospheric temperature, which controls the total radiance received. Hence, for all species, the random error varies latitudinally/seasonally with atmospheric temperature, with a superimposed time dependence on decontamination events. The precision validation involves comparing two MIPAS retrievals at the intersections of ascending/descending orbits. For every 5 days per month of high resolution MIPAS operation, the standard deviation of the statistic of the matching profile pairs is computed and compared with the predicted random error given in the MIPAS Offline L2 data. Even taking into account the propagation of the pressure-temperature retrieval errors into the VMR retrieval, the observed scatter is usually a factor 1-2 larger than the predicted error. This is thought to be due to effects such as horizontal inhomogeneity of the atmosphere.Precision validation of MIPAS-Envisat products
Atmospheric Chemistry and Physics 7:8 (2007) 1915-1923
Abstract:
This paper discusses the variation and validation of the precision, or estimated random error, associated with the ESA Level 2 products from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). This quantity represents the propagation of the radiometric noise from the spectra through the retrieval process into the Level 2 profile values. The noise itself varies with time, steadily rising between ice decontamination events, but the Level 2 precision has a greater variation due to the atmospheric temperature which controls the total radiance received. Hence, for all species, the precision varies latitudinally/seasonally with temperature, with a small superimposed temporal structure determined by the degree of ice contamination on the detectors. The precision validation involves comparing two MIPAS retrievals at the intersections of ascending/descending orbits. For 5 days per month of full resolution MIPAS operation, the standard deviation of the matching profile pairs is computed and compared with the precision given in the MIPAS Level 2 data, except for NO2 since it has a large diurnal variation between ascending/descending intersections. Even taking into account the propagation of the pressure-temperature retrieval errors into the VMR retrieval, the standard deviation of the matching pairs is usually a factor 1-2 larger than the precision. This is thought to be due to effects such as horizontal inhomogeneity of the atmosphere and instability of the retrieval.MIPAS: An instrument for atmospheric and climate research
Atmospheric Chemistry and Physics Discussions 7:3 (2007) 8795-8893
Precision validation of MIPAS-Envisat products
Atmospheric Chemistry and Physics Discussions 7:1 (2007) 911-929
Carbon tetrafluoride from MIPAS measurements
European Space Agency, (Special Publication) ESA SP (2006)