SNAP Data Processors - OLCI MPH/CHL Processor

< SNAP Data Processors - OLCI MPH/CHL Processor

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:

An Algorithm for Detecting Trophic Status (chlorophyll-A), Cyanobacterial-Dominance, Surface Scums and Floating Vegetation in Inland and Coastal Waters
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:

Interpretation of the 685nm peak in water-leaving radiance spectra in terms of fluorescence, absorption and scattering, and its observation by MERIS