Channel 1: 0.52 0.72 VIS

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Channel 1 0.52 - 0.72 ? (VIS)
Radiation Mechanisms Reflection and Scattering of
Solar Radiation Applications clouds ice and
snow cover smoke, pollution, and haze
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Channel 2 3.78 - 4.03 ? (SW IR)
Radiation Mechanisms Reflected solar
radiationEmitted earth radiation.
Applications Detects hot spots from wild
fires Compared to the normal IR channel (Channel
4), liquid water emits less radiation at this
frequency, but ice emits about the same amount.
Therefore we can distinguish between ice and
water clouds.
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Channel 3 6.47 - 7.02 ? (WV)
Radiation Mechanisms Emitted radiation primarily
from atmosphere Applications Detects upper
tropospheric moisture and high clouds. This
wavelength band is effectively absorbed by water
vapor, so little low-level water vapor is
detected. Since synoptic scale disturbances are
normally marked by regions of upward vertical
motion and subsidence, images from this channel
may be used to locate upper-level troughs, jet
streams, and other large scale features such as
the inter-tropical convergence zone.
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Channel 4 10.2 - 11.7 ? (Thermal IR)
Radiation Mechanisms Emitted radiation from
surface and cloud tops Applications Around the
10.7 um region, most of the energy radiated from
the surface reaches the sensor, thus the term
"atmospheric window" since the temperature
measured is close to scene temperature. When
clouds are present, this channel takes the
temperature of the cloud top.
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Channel 5 Split Window or Dirty Window (11.5
12.5?)
Channel 5 has been called the "dirty window"
because the effect of low-level moisture is more
pronounced than in Channel 4. More radiation is
absorbed at this wavelength. The temperature
difference between Channels 4 5, when combined
with the lapse rate and underlying surface
temperature information, allows for estimations
of low-level moisture and instability. The
atmospheric lapse rate normally varies diurnally
over land. Thus, overlying boundary layer
moisture is typically warmer than the surface at
night and during the early morning, and cooler in
the afternoon. This change in vertical
temperature structure will reverse moisture's
effect on this channel's imagery, day versus
night. As with the window channel, thunderstorm
tops do not show any differences due to moisture
contamination.
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Example of Multi-channel Comparison
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Snow Example Visible vs. Reflectivity
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Wildfire Example Visible vs. Reflectivity
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