Radiometry – Foundational physical quantities Radiometry quantifies electromagnetic radiation for remote sensing. Which set of quantities underpins radiometric measurement and analysis?

Introduction / Context:
Radiometry provides the physical framework for measuring and modelling electromagnetic power detected by sensors. Its quantities define how energy is counted, how fast it is delivered, how it is distributed in angle, and how it is emitted or reflected per unit area and solid angle. Mastery of these terms is essential for calibration, atmospheric correction, and inversion of surface properties.

Given Data / Assumptions:

• Passive or active sensing scenarios.
• Standard SI-based radiometric definitions.
• Idealized surfaces and far-field sensor geometry for clarity.

Concept / Approach:

The fundamental set comprises: radiant energy Q (total energy), radiant flux phi (time rate of energy), radiant intensity I (flux per unit solid angle), irradiance E and exitance M (flux per unit area incident or leaving), and radiance L (flux per unit projected area per unit solid angle). Together they describe what a detector measures and how surface-sensor geometry maps power into signals.

Step-by-Step Solution:

Verification / Alternative check:

Sensor calibration documents and textbooks define Level-1 products in terms of radiance and convertance, with flux and energy central to instrument design and exposure control.

Why Other Options Are Wrong:

No single quantity alone is sufficient; the framework needs the complete set to map sources, surfaces, and sensors.

Common Pitfalls:

Confusing radiance L with irradiance E; mixing photometric (luminous) and radiometric terms; ignoring solid angle in intensity and radiance definitions.

Final Answer:

All of these