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Barcelona, July 25, 2007 WATER HM Meeting Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation Shannon Brown Jet Propulsion Laboratory.

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Presentation on theme: "Barcelona, July 25, 2007 WATER HM Meeting Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation Shannon Brown Jet Propulsion Laboratory."— Presentation transcript:

1 Barcelona, July 25, 2007 WATER HM Meeting Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation Shannon Brown Jet Propulsion Laboratory Shannon.T.Brown@jpl.nasa.gov

2 Barcelona, July 25, 2007 WATER HM Meeting Radiometer Land Contamination  Land contamination can be divided into three categories  Far sidelobe contamination  Near sidelobe contamination  Main beam contamination Near sidelobes Mainbeam 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)

3 Barcelona, July 25, 2007 WATER HM Meeting 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 10 km approach at Harvest estimated for AMR ~20 km approach estimated for worst case for AMR

4 Barcelona, July 25, 2007 WATER HM Meeting 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 Barcelona, July 25, 2007 WATER HM Meeting Option 1 NASA Aquarius Heritage for 2.5 m reflector Lightweight Rainfall Radiometer – aircraft heritage for synthetic aperture radiometer technology Visible Camera LRR

6 Barcelona, July 25, 2007 WATER HM Meeting 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 Barcelona, July 25, 2007 WATER HM Meeting 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 22.235 GHz (H 2 O) 55-60 GHz (O 2 ) 118 GHz (O 2 ) 183.31 GHz (H 2 O)

8 Barcelona, July 25, 2007 WATER HM Meeting 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 Barcelona, July 25, 2007 WATER HM Meeting Option 2 Modeled Brightness Temperature to PD and CLW 23.8 GHz 90 GHz 130 GHz160 GHz  90 GHz T B ~8x more sensitive to CLW than 23.8 GHz T B  Sensitivity to high PD decreases with frequency 10 km 2.6 km 2.1 km1.5 km dT B /dPD

10 Barcelona, July 25, 2007 WATER HM Meeting 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 Barcelona, July 25, 2007 WATER HM Meeting 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 183 + 1 183 + 3 183 + 7 166 Height (km) 60 GHz Temperature Weighting Functions 183 GHz Water Vapor Weighting Functions

12 Barcelona, July 25, 2007 WATER HM Meeting 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 Barcelona, July 25, 2007 WATER HM Meeting 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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