CH Remote Sensing & Satellite Imagery

Question 1

What does LiDAR stand for in the context of hydrographic remote sensing?

Accepted Answer

Light Detection And Ranging

Answer

LiDAR stands for Light Detection And Ranging, using laser pulses to measure distances and, in bathymetric applications, water depths.

Question 2

Which type of satellite sensor is most commonly used to measure sea surface temperature (SST) in hydrographic studies?

Accepted Answer

Thermal Infrared (TIR) sensor

Answer

Thermal infrared sensors detect heat emission from the ocean surface, making them the standard tool for sea surface temperature measurement from satellites.

Question 3

What is the primary advantage of multispectral satellite imagery for shallow water bathymetry?

Accepted Answer

It can penetrate clear, shallow water to map the seafloor using light attenuation

Answer

Multispectral imagery exploits differential attenuation of light wavelengths through clear water, enabling seafloor mapping in shallow, transparent conditions typically up to 20–25 m depth.

Question 4

Synthetic Aperture Radar (SAR) is particularly valuable for hydrographic applications because it can:

Accepted Answer

Detect oil spills, ship wakes, and surface roughness regardless of cloud cover or darkness

Answer

SAR operates in the microwave spectrum, penetrating clouds and functioning day or night, making it ideal for detecting surface phenomena such as oil spills, ship wakes, and internal waves.

Question 5

The Secchi depth is used in satellite-derived bathymetry primarily to estimate:

Accepted Answer

Water transparency and maximum depth of optical light penetration

Answer

Secchi depth quantifies water transparency by measuring how deep a white disk remains visible, indicating how far light penetrates and thus the practical depth limit for optical satellite bathymetry.

(CH) Certified Hydrographer Practice Test

(CH) Certified Hydrographer Practice Test

CH Remote Sensing & Satellite Imagery