Calculating BASE

For each pixel in the image, the algorithm calculates BASE as follows:

1. Calculates the azimuthal equidistant (AzEQ) point around the radar.

2. Uses co-ordinates in AzEQ to calculate the distance from the radar(vector length).

3. Checks if the AzEQ point is in the radar's range for the BASE product.

4. Calculates the azimuth angle to radar(atan2).

5. Determines the lowest sweep with a reflectivity value over the threshold.

6. Optimizes the calculation of the minimum height by calculating the height of the lowest point with reflectivity over threshold from the height of the lowest sweep.

   The calculation uses the minHeightOfSweep by calculating downwards until reflectivity is no longer present.

The minimum height of a sweep represents the height with the minimum reflectivity as defined in the threshold.

The algorithm scans downwards until it finds a height for which there is no reflectivity value over the threshold. The last height with a valid reflectivity value is the result.

The final output of the product is a color-coded map of echo BASE heights for the selected dBZ threshold.