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

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 ( mm)

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

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

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

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)

Barcelona, July 25, 2007 WATER HM Meeting Move to Higher Frequency  Maintain 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 GHz (H 2 O) GHz (O 2 ) 118 GHz (O 2 ) GHz (H 2 O)

Barcelona, July 25, 2007 WATER HM Meeting Option 2  Add 1 or 2 channels between GHz to improve the extrapolation of PD from the last uncontaminated ocean pixel to the coast

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

Barcelona, July 25, 2007 WATER HM Meeting Option 2  Add 1 or 2 channels between 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)

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 Height (km) 60 GHz Temperature Weighting Functions 183 GHz Water Vapor Weighting Functions

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

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