Level 2 Algorithm

1
Level 2 Algorithm
2
Definition of Product Levels
3
Science Algorithm Levels

• Level 1
• 1A Reconstructed instrument data
• 1B Instrument units at TOA
• RFI Flag
• Avg over one cal cycle (1.44 sec)
• Level 2
• 2A TA at TOA to surface
• Flags (solar flares, rain, land, etc)
• Faraday rotation correction
• Antenna pattern correction
• Geophysical parameters removed
• TA at surface each 1.44 sec
• 2B TB at surface to SSS
• Roughness correction
• SST model function (Klien-Swift)
• Avg to 5.76 sec
• Level 3 Time-space averaged SSS on standard
  earth-projection

L1 L2A L2B L3
4
Algorithm Modules Level 2

• Input from L1B Antenna temperature avg at 1.44
  sec
• Flags
• Flag Solar Flares
• Rain Flag
• Land Contamination, sea ice
• Excessive winds, foam
• Unusual Antenna Temperature
• Antenna Pattern Correction
• Remove off-earth contribution (galactic, sun,
  limb)
• Tearth Tmeasured Tspace
• Correct for Faraday rotation
• Compute effective Brightness at boresight
• Tbv A11 T1 A12 T2
• Tbh A21 T1 A22 T2
• Remove Geophysical Contributions
• Atmospheric up/down welling and Attenuation
• Reflected galactic and sun
• Correct for land contamination (optional)

5
Level 2A Radiometer Geolocated Calibrated
Sensor Units at Surface

• A. At 1.44 sec working average
• Flags
• Solar Flares, Rain, Land, Sea Ice,
• Excessive Wind, Foam, Unsual TB
• Corrections
• Faraday Rotation
• Galactic Background
• Atmospheric Attenuation and Emission
• Sun and Moon
• Antenna Pattern Correction
• B. Output Geolocated and Calibrated sensor
  units
• Th and Tv at the surface
• One value for each 1.44 sec

6
Level 2B Radiometer Geolocated SSS averaged to
5.76 sec

• A. TB at 1.44 sec
• Roughness Correction (for TB)
• Using Scat data (Algorithm provided by Scat)
• Alternative Using local wind speed and/or
  sea state
• Average
• One data point per 5.76 sec
• Located at center
• Convert to Salinity
• Klein Swift model or latest version
• Output
• Salinity at center of geolocated pixels
• One pixel per 5.76 sec.
• All Flags
• Quality flag (error estimate in salinity units)

7
Level 2 ScatterometerRoughness Correction at
5.76 sec

• A. Scatterometer Output
• NRCS (s0) colocated at 1.44 sec with radiometer
  data
• Roughness Correction (s0 to TB)
• Algorithm derived pre-launch
• Revised post-launch using scat data and
  surface truth
• Wind direction
• Assess importance and if necessary collect
  ancillary data
• B. Other Scatterometer Output
• NRCS at 5.76 sec with flags and quality index
  (Kpc)
• Other
• Archived Output
• NRCS at 1.44 and 5.76 sec
• Flags and quality index
• Ancillary data (wind speed and surface
  roughness)
• Algorithm