THE NEAR-SURFACE LAYER OF THE OCEAN
reflected back to space using a solar zenith angle dependent on cloud albedo
A Z . The remaining transmitted fraction exiting the cloud base, not absorbed
by the surface (determined by surface reflectance, R S ), is reflected upward
and is reflected downwards again from the cloud base (determined by
spherical cloud albedo, A S ).
The International Satellite Cloud Climatology Project (ISCCP) produced
global surface solar irradiance fields for several years (beginning in July
1983) using data from a number of satellites. Data were temporally resolved
every 3 hours and spatially resolved at 0.5 0.5
o
o
u
latitude and longitude.
The major input data set for the ISCCP contained information about clouds,
the atmosphere and the ocean surface at nominal 30 km resolution (4-8 km
pixel size, randomly sub-sampled at 30 km resolution) collected every 3
hours from around the globe (Bishop et al., 1997). These data were then used
to produce a 0.5 by 0.5 degree gridded product. The ISCCP data were
available eight times per day for most of the globe (Figure 1-6) but gaps in
the dataset were present over regions observed less frequently by polar
orbiters rather than geostationary satellites. Validation of this remote sensing
approach to collecting radiation data has been done by Waliser et al. (1999)
by comparisons between buoy-observed, satellite-derived, and modeled
surface shortwave flux over the subtropical North Atlantic for data collected
during the Subduction Experiment.
1.4.5 Albedo of the sea surface
Albedo is the ratio of the amount of electromagnetic radiation reflected
by the surface of a body to the amount incident upon it, commonly expressed
as a percentage. The albedo of the sea surface is defined as follows (Ivanoff,
1977):
/
/
u
d
r
b
d
A I I
I I I
,
(1.54)
where I d is the surface solar irradiance, I r the solar irradiance reflected from
the sea surface, and I b is that part which is upward back-scattered from
below the sea surface. Introducing the reflectance coefficient of the sea
surface,
R s = I r /I d ,
(1.55)
the definition of albedo (1.54) can be rewritten as follows:
/
s
b
d
A R I I
,
(1.56)
26
reflected back to space using a solar zenith angle dependent on cloud albedo
A Z . The remaining transmitted fraction exiting the cloud base, not absorbed
by the surface (determined by surface reflectance, R S ), is reflected upward
and is reflected downwards again from the cloud base (determined by
spherical cloud albedo, A S ).
The International Satellite Cloud Climatology Project (ISCCP) produced
global surface solar irradiance fields for several years (beginning in July
1983) using data from a number of satellites. Data were temporally resolved
every 3 hours and spatially resolved at 0.5 0.5
o
o
u
latitude and longitude.
The major input data set for the ISCCP contained information about clouds,
the atmosphere and the ocean surface at nominal 30 km resolution (4-8 km
pixel size, randomly sub-sampled at 30 km resolution) collected every 3
hours from around the globe (Bishop et al., 1997). These data were then used
to produce a 0.5 by 0.5 degree gridded product. The ISCCP data were
available eight times per day for most of the globe (Figure 1-6) but gaps in
the dataset were present over regions observed less frequently by polar
orbiters rather than geostationary satellites. Validation of this remote sensing
approach to collecting radiation data has been done by Waliser et al. (1999)
by comparisons between buoy-observed, satellite-derived, and modeled
surface shortwave flux over the subtropical North Atlantic for data collected
during the Subduction Experiment.
1.4.5 Albedo of the sea surface
Albedo is the ratio of the amount of electromagnetic radiation reflected
by the surface of a body to the amount incident upon it, commonly expressed
as a percentage. The albedo of the sea surface is defined as follows (Ivanoff,
1977):
/
/
u
d
r
b
d
A I I
I I I
,
(1.54)
where I d is the surface solar irradiance, I r the solar irradiance reflected from
the sea surface, and I b is that part which is upward back-scattered from
below the sea surface. Introducing the reflectance coefficient of the sea
surface,
R s = I r /I d ,
(1.55)
the definition of albedo (1.54) can be rewritten as follows:
/
s
b
d
A R I I
,
(1.56)
26