1. Useful signal
2. Absorbed by atmosphere
3. Scattered out of field of view (FOV)

1 + 2 + 3 SIGNAL received if no atmosphere were present

4. Emitted by atmosphere
5. Atmospheric scattering into FOV
6. Reflected by sea surface into FOV
7. From sea surface outside FOV

4 + 5 + 6 + 7 NOISE

Credits: National Oceanography Centre, Southampton