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OLCI MPH/CHL Processor - Algorithm Specification |

The Maximum Peak Height (MPH) algorithm exploits bottom-of-Rayleigh reflectance peaks in the red and near-infrared bands above a baseline, which is drawn between the bands at 664nm, and 885nm (Matthews et al., 2012). This baseline technique is basically the same used in the Fluorescence Line Height (FLH) and Maximum Chlorophyll Index (MCI) algorithms (Gower et al., 1999).

Different reflectance peak positions occur mostly as a consequence of pigment concentration levels, and these peaks' heights depend on specific optical drivers.

For the most common water types, MPH selects a suitable baseline using a sequence of predefined conditions and thresholds.

Note that this diagram shows the MERIS BRR bands with their original names (brr_*). They were changed to 'rBRR_*' in the SNAP Rayleigh Correction processor, and the mapping from the required MERIS to OLCI bands is as follows:

Wavelength (nm) | MERIS BRR band | OLCI BRR band
619 | brr_6 (rBRR_06) | rBRR_07
664 | brr_7 (rBRR_07) | rBRR_08
681 | brr_8 (rBRR_08) | rBRR_10
709 | brr_9 (rBRR_09) | rBRR_11
753 | brr_10 (rBRR_10) | rBRR_12
885 | brr_14 (rBRR_14) | rBRR_18

## References

- Matthews, M. W., S. Bernard and L. Robertson:

- Matthews, M. W. and D. Odermatt:

  Improved algorithm for routine monitoring of cyanobacteria and eutrophication in inland and near-coastal waters
  (https://doi.org/10.1016/j.rse.2014.10.010)

- Gower, J.F.R., R. Doerffer, and G.A. Borstad: