The proposed research is a three-year effort to address the suitability of the OMPS Limb Profiler (LP) Environmental Data Records (EDRs) for long-term climate research. Our evaluation of OMPS consists of four elements: (1) sensor characterization, (2) assessment and improvement of Sensor Data Record (SDR) and EDR algorithms, (3) end-to-end algorithm testing, and (4) initial calibration/validation activities. First we will review the instrument performance and assess the characterization of the sensor conducted by the manufacturer (Ball Aerospace & Technologies Corporation, BATC). Second, we will use the lessons learnt from our past activities as NPP Science Team members and advisors to the O3OAT, as well as our experience with other Limb Scatter (LS) sensors (SOLSE/LORE, SAGE III), to diagnose the existing inversion algorithms and implement necessary improvements. Third, using both simulated data and synthetic data (created from SAGE III, OSIRIS and SCIAMACHY radiance measurements), we will test each module of the SDR and EDR algorithms and conduct a set of comprehensive end-to-end tests to assess the inversion methods. Finally, we will plan and help execute the initial phase of the validation analysis, which will allow us to characterize the performance of both the sensor and the inversion code using operational data.
To summarize, we propose the following:
- Analyze pre-launch instrument characterization test data
- Develop code to create calibrated inputs (SDRs) to the ozone limb retrieval algorithm
- Develop functional EDR code in time for NPP launch
- Test algorithms using actual LS data (SAGE III, OSIRIS, SCIAMACHY)
- Design and modify retrieval code towards demonstrating Climate Data Record (CDR) quality
- Plan and implement post-launch calibration/validation effort
The ultimate goals of the proposed research are to develop: (1) the necessary processing software, analysis tools and post-launch Cal/Val plans for the OMPS-LP on NPP and (2) a good understanding of the long-term accuracy and precision that can be expected of the OMPS-LP. It is our intent to provide, by launch time, all the tools necessary to assess the performance of the sensor and the algorithm. To achieve this, we are proposing a very active and comprehensive role for the Science Team, encompassing hardware and software issues as well as Cal/Val activities, and including contributions from international experts in the field of LS research.
Out of the three OMPS instruments making up the Ozone Mapping and Profiler Suite (OMPS), the limb profiler has the least heritage and necessitates special attention at the SDR, EDR and CDR levels. Issues such as straylight contamination, altitude registration, sensor calibration and aerosol effect have to be addressed first to ensure that the OMPS-LP can at least meet the level of accuracy and precision achieved by other LS instruments such as OSIRIS, SAGE III and SCIAMACHY (the present State-of-the-Art). Furthermore, to be able to demonstrate data quality at the CDR level, the OMPS algorithm has to take into account effects such as scene inhomogenity, PSC & PMC, along track-inhomogeneity. The validation of the derived ozone data sets will be considered in light of the requirements needed to detect ozone trends into the next decade.
The proposed research depends heavily on the availability of (1) BATC, to conduct the necessary sensor characterization and (2) PEATE, to assist in upgrading and testing the SDR algorithm, EDR code cleanup and testing, configuration control management, science-to-operations conversion, operational data processing, and on-orbit calibration trend analysis.
This proposal is linked to a separate, complementary proposal dealing with the OMPS nadir sensors (Developing Climate Data Records from the OMPS Ozone Mapper and Nadir Profiler Instruments, McPeters, PI), and leverages off the work proposed therein.
