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

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Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation Shannon Brown Jet Propulsion Laboratory [email protected] Radiometer Land Contamination. Land contamination can be divided into three categories Far sidelobe contamination Near sidelobe contamination

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Presentation Transcript
radiometer land contamination
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

main beam contamination
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

radiometer concepts
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
option 1
Option 1

NASA Aquarius Heritage for 2.5 m reflector

Lightweight Rainfall Radiometer – aircraft heritage for synthetic aperture radiometer technology

Visible Camera

LRR

radiometer concepts1
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)
move to higher frequency

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
option 2
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
option 21
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

option 22
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)
option 3

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)

option 31
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
conclusions
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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