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Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation Shannon Brown

Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation Shannon Brown Jet Propulsion Laboratory Shannon.T.Brown@jpl.nasa.gov. Radiometer Land Contamination. Land contamination can be divided into three categories Far sidelobe contamination Near sidelobe contamination

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Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation Shannon Brown

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  1. Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation Shannon Brown Jet Propulsion Laboratory Shannon.T.Brown@jpl.nasa.gov

  2. Radiometer Land Contamination • Land contamination can be divided into three categories • Far sidelobe contamination • Near sidelobe contamination • Main beam contamination Far sidelobes Far sidelobe contamination Correctable to acceptable levels (~ 1mm) Near sidelobe contamination More difficult, but correction is possible (~2-4 mm) Main beam contamination Very difficult to correct (20-40 mm) Mainbeam Near sidelobes

  3. Main Beam Contamination • Along track averaging can improve coastal approach for preferred land/ground track orientations • Additional improvements may be made through correction algorithms based on pattern weighted main beam land fractions ~20 km approach estimated for worst case for AMR 10 km approach at Harvest estimated for AMR

  4. Radiometer Concepts • Option 1: Maintain traditional channel set, but increase antenna dimensions • Real aperture • Synthetic aperture • > 2.5 m aperture required for < 5 km resolution

  5. Option 1 NASA Aquarius Heritage for 2.5 m reflector Lightweight Rainfall Radiometer – aircraft heritage for synthetic aperture radiometer technology Visible Camera LRR

  6. Radiometer Concepts • Option 1: Maintain traditional channel set, but increase antenna dimensions • Real aperture • Synthetic aperture • > 2.5 m aperture required for < 5 km resolution • Pros: • Proven retrieval algorithm • Retrievals in all non-precipitating conditions • High sensitivity to PD over the range of PDs • Cons: • Complications from large real aperture required • Synthetic aperture technique proven in aircraft demonstration, but not yet in space • Difficult to get PD in inland areas (i.e. rivers)

  7. 22.235 GHz (H2O) 118 GHz (O2) 55-60 GHz (O2) 183.31 GHz (H2O) Move to Higher Frequency • Maintain 18-34 GHz channel set for open ocean retrievals • Maintain AMR heritage 1m reflector • Option 2: Include 1-2 higher frequency window channels for coastal PD extrapolation • Option 3: Include temperature and vapor sounding channels for PD retrievals over land and ocean

  8. Option 2 • Add 1 or 2 channels between 90-150 GHz to improve the extrapolation of PD from the last uncontaminated ocean pixel to the coast

  9. Option 2 Modeled Brightness Temperature to PD and CLW • 90 GHz TB ~8x more sensitive to CLW than 23.8 GHz TB • Sensitivity to high PD decreases with frequency 23.8 GHz 90 GHz 2.6 km 10 km dTB/dPD 130 GHz 160 GHz 2.1 km 1.5 km

  10. Option 2 • Add 1 or 2 channels between 90-150 GHz to improve the extrapolation of PD from the last uncontaminated ocean pixel to the coast • Pros: • Relatively small perturbation to add two channels in this frequency range • These channels will have < 5 km resolution with 1 m reflector • Cons: • These channels will loose sensitivity to PD for high PD values • Performance can be affected in variable cloud conditions near coast • Not likely to be able to get PD in inland areas (i.e. rivers)

  11. 183 + 1 183 + 3 183 + 7 166 Option 3 • Add temperature and water vapor sounding channels to retrieve PD over land and coast (channels near 50 or 118 GHz and channels near 183 GHz) • Will likely need 2-3 temperature sounding channels and 4 water vapor sounding channels 60 GHz Temperature Weighting Functions 183 GHz Water Vapor Weighting Functions Height (km)

  12. Option 3 • Add temperature and water vapor sounding channels to retrieve PD over land and coast (channels near 50 or 118 GHz and channels near 183 GHz) • Pros: • Should be able to retrieve PD over land or water • High resolution < 5 km • Cons: • Reduced accuracy in clouds • Reduced sensitivity to PD in moist conditions • Uncertain with what accuracy this can be done

  13. Conclusions • Option 1: Large antenna • Scientific Risk: Low • Engineering Risk: Medium • Option 2: Higher frequency window channels • Scientific Risk: Medium • Engineering Risk: Low • Option 3: Temperature and water vapor sounding channels • Scientific Risk: Medium • Engineering Risk: Medium

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