Patch/nasc

[simedroniraluca]

NASC (Nautical Area Scattering Coefficient) Computation Correction

This PR is opened to propose a solution for OSOceanAcoustics#1136

Changes Made:

1. Conversion Factors: Conversion factors have been incorporated to facilitate the conversion from backscattering cross-section to scattering cross-section and from meters to nautical miles (nmi).

2. Computation Approach:

   • Cells Selection: Cells are chosen based on their depth and distance. The distance calculation is based on latitude and longitude coordinates.
   • NASC Calculation: For each channel and cell, the NASC is computed using the following steps:
     • Multiply the Sv (in linear units) with the height of the samples. The sample height is determined as the difference between consecutive depth values.
     • Compute the mean of the obtained values.
     • Multiply the mean value by the number of samples within the selected cell per the number of pings in the same cell.
     • Further multiply the result by $4 \times \pi \times 1852^2$
     • Finally, divide the obtained result by the percentage of non-NaN samples present in the analysis.

[ruxandra-valcu]

Closing since not part of our workflow anymore