GEOG 271 pt 2 Flashcards
What does the Stefan-Boltzmann equation tell us?
All the radiation emitted from a target, so everything under the curve.
What is an atmospheric window?
A part of the electromagnetic spectrum in which the atmosphere does not absorb all of the incident energy but transmits it effectively.
If we wanted to differentiate between a manmade and natural waterbody, what image interpretation ‘tools’ could we use?
Association, shape and pattern
What is the difference between a black and gray body?
The emissivity of the body or material.
Why does the sky appear blue?
Rayleigh scattering, Light travels a shorter distance
What is radiometric resolution?
The number of gray levels in an image.
A standard false colour composite includes which satellite bands?
Near-infrared, Red, Green
What is a specular surface?
A surface that reflects radiation like a mirror.
Which is the best band(s) to use if we wanted to map the bathymetry of lakes?
Green
Which biophysical parameter is responsible for the high reflectance of near-infrared from vegetation?
Cell structure
We know that NDVI was purposely developed for monitoring vegetation growth. Which surface would have the lowest NDVI?
Early season crops
Which bands of Landsat-8/9 are best for discriminating between snow and cloud cover ?
Bands 6 and 7
Smaller snow grains have what impact on reflectance from snow cover?
increased reflection of solar radiation for all wavelengths
What is the impact of increased algae on reflectance from waterbodies?
To increase reflectance of green light
What is the impact of decreased organic matter content in soils?
To increase reflectance at all wavelengths
Which of the following do not follow a near-polar orbit?
A)
Landsat
B)
Terra
C)
GOES
D)
MODIS
E)
SPOT
GOES
If we wanted to study a change in the health of a forest since 1985, which satellite would be the best choice?
A)
Landsat
B)
MODIS
C)
SPOT-7
D)
Worldview-3
E)
Planet DOVE
Landsat
If we wanted to measure the size of individual tree crowns in a local neighborhood, which satellite would be best?
A)
Landsat
B)
GOES
C)
MODIS
D)
SPOT
E)
Worldview-3
Worldview-3
Why do thermal remote sensors not look at the full range of wavelengths between 3 - 14 μ?
There are areas with 0 atmospheric transmission
If two objects have the same kinetic temperature but different radiant temperature - what does that mean?
The object with a higher radiant temperature has a higher emissivity
Which of the following materials exhibit large temperature fluctuations during a 24-hour period on a sunny day?
A)
Water
B)
Moist soil
C)
Rocks
D)
B and C
E)
A and B
Rocks
Thermal inertia is a measurement of the thermal response of a material to temperature changes. Which of the following variables influence the thermal inertia of a material?
Density, thermal capacity, thermal conductivity
What is a selective radiator?
A material that is characterized by variable emissivity values at different wavelengths
If looking at a thermal image acquired during nighttime, what landcover might you expect to have the highest brightness temperature?
Urban
What is the basic principle behind why we can obtain measurements in the thermal wavelengths of the electromagnetic spectrum?
All objects with a temperature greater than 0 K emit energy in these wavelengths, There is some relation between an object’s radiant and kinetic temperature
If we wanted to observe a forest fire with a temperature of 800 K, what range would we want our sensor to capture?
3 - 5 μm
What does RADAR stand for?
Radio Detection and Ranging
What is the main difference between active and passive sensors?
Active sensors emit their own source of EMR
Why is SAR the best option for RADAR imagery from space?
Antenna length
Which of these is an advantage of RADAR over an optical system?
Can be used at any time of day, Can penetrate cloud cover (all-weather)
What would we expect the dominant scattering mechanism to be for a swamp with emergent vegetation (trees) when using an X-band system?
Volume Scattering,
Double Bounce
What determines whether water appears bright or dark in a RADAR image?
Roughness of the water, The wavelength of the RADAR sensor
If we wanted to study soil moisture in the Amazon rainforest, which wavelength would we use?
L-band
When interpreting thermal infrared we are mainly looking at surface (skin) temperature. For passive microwave, what are we primarily interpreting?
Emissivity
Under what circumstances would the decrease in brightness temperature from soil be lowest with increasing moisture content?
Soil is cooler
If we wanted to differentiate between dry and wet snow would we want to use a high or low passive microwave frequency? Why?
High frequency, scattered by dry snow
