the ocean color are based on, or derived from
basic radiometric quantity called
water—leaving radiance _L…( À), "is the radiance ‘wh‘iCh emergeÏsform theocéan. The
radiance received at spacecraft altitudes is modified principally by solar irradianœ
'
scattering a'nd absorption from the
(molecular
”suspended in the air‘ (aerosol—Wie] scattering),
surface
reections (sun and sky glitter), and finally, from within the ocean, water molecules and
dissolved-and Suspended particles. The process of derivingthe water—leaving radiances
from satellite imagery of the oceans is termed "atmospheric correction." To remove the
'
major
effects the atmosphere has onthe radiance that are reflected from the
'
.
ocean back up into ”space. The
correction algOrithm utilizes radiance data at
765 and 865 nm. The
the,assumpon
light radiated from the
ocean
surfaCe at' 670 nm, and thus all of the light deteèted wäs‘due to Rayleigh
scattering from air
aerosolsCattèring..
improveson this scheme
—
by
at 765 and 865…nm‘,fasa
may actually radiate
from
at 670 nm. Furthermore,üthe “_atm,os_pheïric cbrrection' sCheme used by
SeaWiFS more accurately reprod‘uces variable atmosphericConditionsï(GŒddn and Wang,
1994). Once the radiance has been côrrectedfor
the signal
is corrected for the solar Zenith angle to derive water—leaving radiance.
The
SeaWiFS
(Sea-viewing Wide—Field%pf
Sensor) on" board the SeaStar
spacecraft is an advanced sensor designed for….ocean monitoring It consists of eight
spectral bands of very narrow wavelength ranges"(sea table below)
for- very
specific detection and monitoring Of’vari0us ocean phenomena including: ocean primary
production and phytoplankton
oc‘ean influences on climate processes (heat
storage and aerosol formation), and monitoring of the cycles of carbon, sulfur, and
nitrogen. Commercial applications have ranged from fishing to navigation, weather
prediction, and agriculture (Lillesand, 1999).
'
—
The-orbit altitude 'iS“705—' kaitha
Crossing time of 12 PM. Two
combinations of spatial resolution ahd swath width are-available for” each band: a higher
resolution mode of 1.1_ km (at nadir) over a swath of 2800 km, and a lower resolution
mode of 4.5 km (att nadir) over a swath of 1500 km. Thefollowingtable…illustrates the
SeaWiFS sensor system
following.
figure Shows an example of SeaWiFS image acquired for_ Mediterranean region.
Bio—optical Algorithm for deriving
from SeaWiFS Satellite Data
basic radiometric quantity called
water—leaving radiance _L…( À), "is the radiance ‘wh‘iCh emergeÏsform theocéan. The
radiance received at spacecraft altitudes is modified principally by solar irradianœ
'
scattering a'nd absorption from the
(molecular
”suspended in the air‘ (aerosol—Wie] scattering),
surface
reections (sun and sky glitter), and finally, from within the ocean, water molecules and
dissolved-and Suspended particles. The process of derivingthe water—leaving radiances
from satellite imagery of the oceans is termed "atmospheric correction." To remove the
'
major
effects the atmosphere has onthe radiance that are reflected from the
'
.
ocean back up into ”space. The
correction algOrithm utilizes radiance data at
765 and 865 nm. The
the,assumpon
light radiated from the
ocean
surfaCe at' 670 nm, and thus all of the light deteèted wäs‘due to Rayleigh
scattering from air
aerosolsCattèring..
improveson this scheme
—
by
at 765 and 865…nm‘,fasa
may actually radiate
from
at 670 nm. Furthermore,üthe “_atm,os_pheïric cbrrection' sCheme used by
SeaWiFS more accurately reprod‘uces variable atmosphericConditionsï(GŒddn and Wang,
1994). Once the radiance has been côrrectedfor
the signal
is corrected for the solar Zenith angle to derive water—leaving radiance.
The
SeaWiFS
(Sea-viewing Wide—Field%pf
Sensor) on" board the SeaStar
spacecraft is an advanced sensor designed for….ocean monitoring It consists of eight
spectral bands of very narrow wavelength ranges"(sea table below)
for- very
specific detection and monitoring Of’vari0us ocean phenomena including: ocean primary
production and phytoplankton
oc‘ean influences on climate processes (heat
storage and aerosol formation), and monitoring of the cycles of carbon, sulfur, and
nitrogen. Commercial applications have ranged from fishing to navigation, weather
prediction, and agriculture (Lillesand, 1999).
'
—
The-orbit altitude 'iS“705—' kaitha
Crossing time of 12 PM. Two
combinations of spatial resolution ahd swath width are-available for” each band: a higher
resolution mode of 1.1_ km (at nadir) over a swath of 2800 km, and a lower resolution
mode of 4.5 km (att nadir) over a swath of 1500 km. Thefollowingtable…illustrates the
SeaWiFS sensor system
following.
figure Shows an example of SeaWiFS image acquired for_ Mediterranean region.
Bio—optical Algorithm for deriving
from SeaWiFS Satellite Data