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Difficulty: MediumGIS and Remote Sensing Fundamentals

During a flood monitoring operation along the Benue River basin, hydrologists require satellite imagery that can penetrate dense cloud cover and function effectively during both day and night. Which remote sensing system is most suitable for this task?

  1. Active microwave radar remote sensingAnswer
  2. B
    Passive optical multispectral sensing
  3. C
    Thermal infrared radiometry
  4. D
    Panchromatic aerial photographic survey

Answer

Active microwave radar remote sensing is the most suitable system because radar operates at long electromagnetic wavelengths that penetrate clouds and rain, and active sensors supply their own illumination allowing night-time imaging.
Active microwave radar remote sensing uses synthetic aperture radar (SAR) or similar active instruments that generate their own radiation in the microwave portion of the spectrum. Long microwave signals penetrate cloud cover, fog, and rain, while self-illumination allows data acquisition regardless of daylight.

Step-by-Step Solution

1
Analyze the operational constraints specified in the scenario.
Identified key requirements: cloud penetration and round-the-clock (day/night) imaging capacity.
Selecting an appropriate remote sensing sensor requires matching environmental conditions with sensor spectral bands and energy sources.
2
Evaluate sensor energy source types (active vs. passive).
Active sensors emit their own energy pulses and do not depend on solar radiation, enabling night operation.
Passive sensors relying on reflected solar radiation cannot acquire data at night.
3
Evaluate atmospheric penetration across spectral bands.
Microwave wavelengths (1 mm to 1 m) easily pass through atmospheric cloud droplets and precipitation particles.
Shorter visible and infrared wavelengths suffer severe atmospheric scattering and absorption by clouds.

Key Concept

Active vs. Passive Remote Sensing and Microwave Atmospheric Transmission
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Topics

GIS and Remote Sensing Fundamentals

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