NASA Educational Workshop

SeaWiFS: Atmospheric Correction

We want to measure the "color" of the ocean, but we actually measure ocean + atmosphere. The atmosphere is 90% of the signal, and it must be accurately modeled and removed.


Effects of the Atmosphere

Gaseous Absorption

Transparency Windows


Light Paths to the Sensor

Scattering and Attenuation

Scattering and Attenuation

Atmospheric Correction Equation

Lt = Lr + (La + Lra) + tLwc + TLg + t Lw

SeaWiFS "True-Color" Image Near Hawaii


Retrieval of Lw from typical pixel near Hawaii

Radiance Plot

SeaWiFS Derived Chlorophyll Near Hawaii

Hawaii Chlorophyll

Seasonal Chlorophyll

SeaWiFS Calibration and Validation Process

CalVal chart

SeaWiFS Lunar Observations


Lunar Viewing Geometry

SeaWiFS Lunar Calibration

Correction for Long-term Detector Degradation

Lunar Calibration

Comparison with in situ (field) measurements

In Situ

rainbow line

SeaWIFS biosphere globe

SeaWiFS Project Home Page

Bryan Franz(