<s>
Water	B-General_Concept
Remote	I-General_Concept
Sensing	I-General_Concept
is	O
the	O
observation	O
of	O
water	O
bodies	O
such	O
as	O
lakes	O
,	O
oceans	O
,	O
and	O
rivers	O
from	O
a	O
distance	O
in	O
order	O
to	O
describe	O
their	O
color	O
,	O
state	O
of	O
ecosystem	O
health	O
,	O
and	O
productivity	O
.	O
</s>
<s>
Water	B-General_Concept
remote	I-General_Concept
sensing	I-General_Concept
studies	O
the	O
color	O
of	O
water	O
through	O
the	O
observation	O
of	O
the	O
spectrum	O
of	O
water	O
leaving	O
radiance	O
.	O
</s>
<s>
Water	O
quality	O
monitoring	O
by	O
remote	B-Application
sensing	I-Application
and	O
close-range	O
instruments	O
has	O
obtained	O
considerable	O
attention	O
since	O
the	O
founding	O
of	O
EU	O
Water	O
Framework	O
Directive	O
.	O
</s>
<s>
Water	B-General_Concept
remote	I-General_Concept
sensing	I-General_Concept
instruments	O
(	O
sensors	O
)	O
allow	O
scientists	O
to	O
record	O
the	O
color	O
of	O
a	O
water	O
body	O
,	O
which	O
provides	O
information	O
on	O
the	O
presence	O
and	O
abundance	O
of	O
optically	O
active	O
natural	O
water	O
components	O
(	O
plankton	O
,	O
sediments	O
,	O
detritus	O
,	O
or	O
dissolved	O
substances	O
)	O
.	O
</s>
<s>
Thus	O
,	O
the	O
values	O
of	O
remote	B-Application
sensing	I-Application
reflectance	O
,	O
an	O
AOP	O
,	O
will	O
change	O
with	O
changes	O
in	O
the	O
optical	O
properties	O
and	O
concentrations	O
of	O
the	O
optically	O
active	O
substances	O
in	O
the	O
water	O
.	O
</s>
<s>
Accurate	O
calibration	O
of	O
the	O
relationships	O
and/or	O
models	O
used	O
is	O
an	O
important	O
condition	O
for	O
successful	O
inversion	O
on	O
water	B-General_Concept
remote	I-General_Concept
sensing	I-General_Concept
techniques	O
and	O
the	O
determination	O
of	O
concentration	O
of	O
water	O
quality	O
parameters	O
from	O
observed	O
spectral	O
remote	B-Application
sensing	I-Application
data	O
.	O
</s>
<s>
However	O
,	O
the	O
development	O
of	O
water	B-General_Concept
remote	I-General_Concept
sensing	I-General_Concept
techniques	O
(	O
by	O
the	O
use	O
of	O
satellite	O
imaging	O
,	O
aircraft	O
or	O
close	O
range	O
optical	O
devices	O
)	O
did	O
n't	O
start	O
until	O
the	O
early	O
1970s	O
.	O
</s>
<s>
spectrometers	O
,	O
radiometers	O
)	O
,	O
airplanes	O
or	O
helicopters	O
(	O
airborne	O
remote	B-Application
sensing	I-Application
)	O
and	O
satellites	O
(	O
space-borne	O
remote	B-Application
sensing	I-Application
)	O
,	O
the	O
light	O
energy	O
radiating	O
from	O
water	O
bodies	O
is	O
measured	O
.	O
</s>
