Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation - PowerPoint PPT Presentation

About This Presentation
Title:

Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation

Description:

Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation. Shannon Brown ... Radiometer Land Contamination. Land contamination can be divided into ... – PowerPoint PPT presentation

Number of Views:57
Avg rating:3.0/5.0
Slides: 14
Provided by: shanno86
Category:

less

Transcript and Presenter's Notes

Title: Radiometer Concepts for Coastal and Inland Wet Path Delay Estimation


1
  • Radiometer Concepts for Coastal and Inland Wet
    Path Delay Estimation
  • Shannon Brown
  • Jet Propulsion Laboratory
  • Shannon.T.Brown_at_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
  • gt 2.5 m aperture required for lt 5 km resolution

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

6
Radiometer Concepts
  • Option 1 Maintain traditional channel set,
    but increase antenna dimensions
  • Real aperture
  • Synthetic aperture
  • gt 2.5 m aperture required for lt 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
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 lt 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
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 lt 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
Write a Comment
User Comments (0)
About PowerShow.com