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Antenna Pattern correction methods Researcher EPSSG MWI ICI
2015-08-07 18:07:35| Space-careers.com Jobs RSS
Study on Antenna Pattern correction methods for EPSSG MWI and ICI One of our Space Clients in Germany is looking for a researcher to work on a study exploring the possible methodologies to perform the antenna pattern correction APC to transform the antenna radiance into the radiance of the beam associated to each footprint on ground at microwave MW and submmwave frequencies used by the passive imagers that will be on board of the EPSSG satellites. The submission deadline for applicants is August 31st 2015. Study objectives Antenna pattern correction APC is an important part of the Level 1B L1B processing of microwave imager data. The APC removes unwanted contributions from retrieved antenna radiance data. This assures that remotely sensed information passed to data assimilation systems can be successfully used without further processing. The APC generally performs three steps when retrieving linearly polarized radiance information horizontal andor vertical 1 Removal of crosspolarised contamination. 2 Removal of Horn Spillover. 3 Removal of Main Reflector Emission. 4 Removal of other contributions from the instrument structure. 5 Removal of sidelobe contributions from the external antenna pattern of the instrument. The first step can be generally performed when both polarizations are observed. Spillover contribution, main reflector emission and contributions for the instrument structure depend on details of the instruments design which are still under refinement at this stage. The present study focuses on the fifth step of the APC procedure for the Earth view part of the scan, taking also into account the first step see section 4.2. Microwave radiometers for EPSSG are required to have at least 95 beam efficiency signal in the main lobe, defined as the region within 2.5 times the half power beam width HPBW. The remaining part, coming from far secondary lobes or sidelobes, should therefore be removed from the antenna temperature to retrieve only the main lobe brightness temperature. These secondary lobes are affected by the Earth scene itself, and eventually even by the satellite structure, which may reflect radiation coming from the Earth andor directly contribute to the received signal by thermal emission. The main issue is that, due to orbital movement and Earth scene natural variation, top of the atmosphere TOA radiative contribution of the Earth emitted directly or reflected by the satellite within the sidelobes is highly variable. This study aims to explore effective ways to perform the removal of sidelobe contribution in the Earth view that could be applied in the operational processing to generate Level 1B data from MWI and ICI Level 0 raw instrument data. The main objective of the study is to discuss and test the possible sidelobes correction methods using idealized and realistic antenna patterns, providing an objective assessment and the associated software for the most promising methods. MWI and ICI characteristics applicable to the study The MWI will be a conically scanning instrument, as the SSMI Special Sensor MicrowaveImager and the AMSRE Advanced Microwave Scanning Radiometer for EOS. The ICI will be a conical scanning radiometer observing in the microwave and submm wave range. Study tasks The following tasks are to be performed within this study 1 Antenna pattern definition Input Literature, this SOW, any suitable analysis tool. Output Technical report 1, antenna patterns for MWI and ICI, projection of antenna patterns on ground. 2 Assessment of APC methods Optimum Interpolation OI of nearby observations in the Earth view e.g. RD5, RD6, RD7. RD5 considers also the treatment of crosspolarization contribution. Use of climatological radiance maps as suggested by RD8. Use of NWP fields coupled to a radiative transfer model to compute the Earth scene radiance. This method requires all the necessary boundary conditions surface characterization and atmospheric properties in order to compute the outgoing radiance at the top of the atmosphere TOA. Any other relevant method documented in literature, if applicable. In this respect, a literature search shall be performed as well. Input Literature, this SOW, Output from Task 1, any suitable analysis tool. Output Task 2 Technical Report and documentation of Task 2. 3 Development of the sidelobe correction software Input Output from Task 1 and Task 2. Output 1. Sidelobe correction software package including source code, auxiliary datasetsconfiguration, reference input and output, and documentation user guide, highlevel architecture 2. Full technical report including documentation of Task 3 and executive summary. Deliverable items Updated technical reports implementing comments fromthe client after each task. Monthly progress reports a short report to be submitted by email in the first week of every month. Presentation material from the review meetings and minutes of meetingsteleconferences. Good English skills are essential as all documentation and presentation material shall be written in English.
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