OCEAN PARAMETERS FROM NPPNPOESS

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OCEAN PARAMETERS FROM NPP/NPOESS

• Wayne E. Esaias
• NASA GSFC Code 614.2
• October 27, 2005
• wayne.esaias_at_nasa.gov

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Ocean EDRs Ocean Color VIIRS
NPP/NPOESS Sea Surface Temperature IR VIIRS
NPP/NPOESS Sea Surface Temperature CMIS
NPOESS (Microwave)
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• IMPORTANCE of OCEAN COLOR
• Ocean color is a new Requirement for the
  operational system.
• Visible ocean bio-optical reflectance of surface
  layer (lt30 m).
• Provides estimate of marine ecosystem state
  (bio-optical absorption, scattering, chlorophyll)
  and variability.
• Primary observable for marine ecosystem studies
  and the
• ocean carbon system. Direct applications for
  Harmful Algal Bloom events, Hazards, and
  fisheries activities/science.
• Describes variations in solar energy penetration
  (heat).
• Provides estimate of near-surface visibility
  (divers, detection)
• and depth.
• Flow visualization complements temperature
  patterns.

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MODIS HERITAGE CHLOROPHYLL 8-Day AVERAGE
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Ocean Color Products
Heritage MODIS, SeaWiFS (Research Products) 5
normalized water leaving radiance 412, 443, 490,
555, 670 Chlorophyll a absorbance, scattering at
5 wavelengths Algorithms Atmospheric Correction
- Based on heritage algorithms, VIIRS Cloud
Mask OMPS Ozone In-water Algorithms - Based on
MODIS semi-analytic model
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VIIRS OCEAN COLOR ATTRIBUTES SNR and Spatial
Resolution improve over heritage. Seven Vis/NIR
bands (520 nm and fluorescence capability are
omitted). Radiometric stability is crucial.
Stability tests are planned. Rqmts 2
calibration, 0.3 stability, 1 NEdL between
detectors Polarization sensitivity is specified
to be less than 2 (MODIS 6, SeaWiFS
lt.5) Ability to characterize polarization may
be a limiting factor. Polarization ray trace
modeling is being pursued at NGST, and GSFC
(Waluschka et al./Voss). Solar Diffuser will
permit orbit by orbit calibration when Earthshine
is excluded (modification underway). Uncertainty
requirements are stratified (low, med, high Chl)
and challenging.
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Will NPP VIIRS Provide Heritage Quality Sensor
Data for Ocean Color?

• Ocean Color is technically challenging, and
  radiometric requirements have been an instrument
  driver.
• At the present stage of EDU testing, VIIRS
  sensor observations are expected to be of
  heritage quality after on- orbit tuning and
  calibration.
• Initialization, on-orbit cal/val, processing,
  archive and distribution of value-added products
  are still being worked.

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Sea Surface Temperature

• A Key variable for climate change studies.
• Air-Sea temperature differences help control
  ocean-atmosphere coupling and transfer of heat,
  momentum, and gases. Essential for weather
  forecasting, climate and ecosystem process
  studies...
• Patterns in SST reveal ocean currents...
• Satellite radiometers provide the best method for
  producing globally consistent data.

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MODIS HERITAGE DAYTIME SST - 8 Day AVERAGE
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SKIN and BULK SST Skin SST Sensed by IR,
mwave sensors Controls sea-air exchange Up to 0.5
Cooler than Bulk Slight windspeed
dependency Bulk SST More analogous to buoy
SST Reflective of the heat content of the upper
mixed layer Preferred by some climate models
Meters
Eifler Donlon 2001
Minnett et al.
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VIIRS SST Requirements Range 271-313 K HCS 0.75
km Nadir, 1.13 Worst Case (Improved over 4 km
GAC) Uncertainty (Skin) 0.35 K for favorable
conditions (lt 285K, lt40 scan, no
adjacent clouds, no cirrus, AOT lt 0.2)
0.5 K for clear but not
favorable Uncertainty (Bulk) 0.5 K Precision
(Skin Bulk, Clear) 0.27 K Long term
stability 0.1 K
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DECREASED AEROSOL EFFECTS WITH 4 MICRON SPLIT
WINDOW
K
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MODIS NIGHT TIME PERFORMANCE
Minnett et al.
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VIIRS SST ALGORITHM
Day and Night - Dual Split Window Quadratic, 8
coefficients Glint avoidance, Aerosol
correction TS a0 a1 T11 a2T12a3(sec(z)-1)
a4 T3.7 a5T4.0 a6T3.7cos(zs)
a7T4.0cos(zs) a8(T11-T12)2 AVHRR NLSST
/MODIS (Day) TS a0 a1 T11 a2TSFC(T11-T12)
a3 (T11-T12) (sec(q)-1) MWIR (SST4) algorithm
used only at night for MODIS SST4 c0 c1
T11 c2T3.9 c3 (T3.9-T4) (sec(q)-1) The VIIRS
algorithm is considerably more complex than
heritage and interactions are ongoing.
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Microwave All Weather SST - CMIS
HERITAGE SSM/I, SSMIS TMI on TRMM AMSR E on
AQUA CMIS REQUIREMENTS Range 271-313 K HCS
50 km Uncertainty (Skin Bulk) 0.5 K
Precision (Skin Bulk) 0.5 K Long term
stability 0.1 K Performance will degrade in some
weather, observing conditions First available on
NPOES
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http//www.ssmi.com/sst/sst_data_daily.html
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Oceans Summary

• NPP/NPOESS Ocean Products represent a significant
  upgrade/transition of heritage RD capability to
  the on-going operational system, which will be of
  great benefit to the nation.
• Many instrumental and IT challenges have been
  overcome, and some continue to be worked, to
  ensure that this endeavor is successful.