The OMPS Limb Profiler instrument: Data analysis and retrieval algorithm

The Ozone Mapping and Profiler Suite (OMPS) is scheduled to be launched on the NPOESS Preparatory Project (NPP) platform in early 2011. The OMPS will continue monitoring ozone from space, using three instruments, namely the Total Column Mapper (heritage: TOMS, OMI), the Nadir Profiler (heritage: SBUV) and the Limb Profiler (heritage: SOLSE/LORE, OSIRIS, SCIAMACHY, SAGE III). The collection of this ozone data is aimed at fulfilling the U.S. treaty obligation to monitor the ozone depletion for the Montreal Protocol to ensure no gaps in ozone coverage.

The paper will describe the data analysis method being presently developed to retrieve ozone vertical distribution from the radiance data measured by the Limb Profiler (LP). The OMPS-LP instrument was designed based upon the SOLSE/LORE heritage and is specially conceived to minimize stray light. The sensor simultaneously images the whole vertical extent of the Earth's limb through three vertical slits, each horizontally spaced at 250 km cross-track interval and covering a vertical tangent height range of 100 km. The calibration stability, which is essential to enable long-term ozone monitoring, is maintained by periodic observations of the sun, using a transmissive diffuser to redirect the solar irradiance into the telescope. To satisfy the anticipated science needs, the accuracy/precision requirements imposed upon the OMPS-LP instrument are tight, ranging from 10% ozone profile accuracy and 3km vertical resolution specifications to the 3% precision requirement from the tropopause to 55km. The data analysis tools being developed are concerned with (1) instrument effects (straylight decontamination, finite spectral and spatial bandpasses, spectral, spatial registration, absolute calibration) and (2) retrieval of ozone distribution from measured radiances. The data analysis methodology will be described in some details in the paper.