Geography Reference
In-Depth Information
30
28
26
24
22
20
18
16
Kinetic temperature (ground truth)
Radiant temperature (TIR)
Predicted temperature (model)
14
12
10
132
147
162
177
192
207
222
237
252
267
282
Distance upstream (km)
Figure 5.4 Longitudinal profile of water temperature in the upper Grande Ronde River (Oregon, USA) depicting radiant
temperature acquired during an airborne FLIR overflight (20 August 1999), in-stream measurements of kinetic temperature, and
calibrated model predictions. Distance upstream (x-axis) was determined from the river mouth (Oregon Department of
Environmental Quality, 2010a, b).
sensing so that water resources managers and scien-
tists can evaluate how this technology can be used both
to address management needs in water quality assess-
ment and biological conservation and also to further
the understanding of hydrological processes and riverine
ecosystems.
in Figure 5.5. The theory of thermal properties of natural
materials is extensively covered in the literature, and for
the thermal remote sensing of water, specifically, we rec-
ommend a good introductory text (e.g., Mather, 2004;
Lillesand et al., 2008) or overview (e.g., Atwell et al., 1971;
Prakash, 2000).
5.3.1 Remotesensing intheTIRspectrum
5.3 Technical background to the TIR
remote sensing of water
All materials with a temperature above 0 K emit radia-
tion, and as described by Wien's Displacement Law, the
hotter the object, the shorter the wavelength of its emitted
radiation. For example, the sun's temperature is approxi-
mately 6000 K, and the sun emits its peak radiation in the
visible part of the electromagnetic spectrum (0.4-0
This section focuses on the technical considerations nec-
essary for informed planning and implementation of
studies that use TIR remotely sensed images for monitor-
ing streams and rivers. We therefore focus in this section,
firstly, on the theoretical basis of the TIR remote sensing
of water in general, and secondly, on the topics specific to
the TIR remote sensing of riverine landscapes. We explic-
itly use the terminology of either the TIR remote sensing
of water or of rivers to refer to whether the background
applies to water in general, or to water in streams and
rivers. A summary of the suggested processing required
of TIR data to determine water temperature can be found
m)
to which the human eye is adapted. Remote sensing
in the region of visible, near infrared (NIR) and mid-
infrared radiation (
.
8
μ
m) utilises reflected radiation. In
contrast, the earth's ambient temperature is
<
3
μ
300 K and
its peak radiation is emitted at the longer wavelength
of 9
m. Thermal remote sensing captures radiation
emitted in these longer wavelengths (3-1000
.
7
μ
m). As TIR
observations are strongly affected by radiation absorbed
μ
 
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