Preprint Article Version 1 This version is not peer-reviewed

Estimating Chlorophyll-a Absorption with the Total Algae Peak Integration Retrieval TAPIR Considering Chlorophyll-a Fluorescence from Hyperspectral Top of the Atmosphere Signals in Optically Complex Waters

Version 1 : Received: 13 February 2018 / Approved: 14 February 2018 / Online: 14 February 2018 (07:11:09 CET)

How to cite: Keck, T.; Preusker, R.; Fischer, J. Estimating Chlorophyll-a Absorption with the Total Algae Peak Integration Retrieval TAPIR Considering Chlorophyll-a Fluorescence from Hyperspectral Top of the Atmosphere Signals in Optically Complex Waters. Preprints 2018, 2018020097 (doi: 10.20944/preprints201802.0097.v1). Keck, T.; Preusker, R.; Fischer, J. Estimating Chlorophyll-a Absorption with the Total Algae Peak Integration Retrieval TAPIR Considering Chlorophyll-a Fluorescence from Hyperspectral Top of the Atmosphere Signals in Optically Complex Waters. Preprints 2018, 2018020097 (doi: 10.20944/preprints201802.0097.v1).

Abstract

The Total Algae Peak Integration Retrieval TAPIR relates the chlorophyll-a absorption coefficient at 440 nm (a440) to the reflectance peak near 683 nm induced by chlorophyll-a properties. The two-step retrieval provides both the hyperspectral quantification of the phytoplankton fluorescence and scattering and the estimation of a440 from reflectance signals. Integrating the peak, the Total Algae Peak (TAP) accounts for the variance in the peak's magnitude, shape, and central peak wavelength. TAPIR is a solely optical approach estimating a440 and supports the application of retrieval-independent individual regional bio-optical models afterwards to retrieve the chlorophyll-a concentration. Simulations reveal the major sensitivity on the considered model chlorophyll-a absorption spectrum and its single scattering albedo. Additional water and atmosphere constituents have a low impact. An uncertainty assessment reveals uncertainties of less than 30% for TAPIR a440 greater than 0.8 m-1 and less than 38% for lower a440. In optically complex waters, first validation efforts promise the applicability of TAPIR for high chlorophyll-a concentration estimations in the presence of additional water constituents. The technique is generic and considers external conditions (sun zenith angle, number of measurement bands, surface or satellite measurements, and radiometric quantity). TAPIR applies to all kind of waters including optically complex waters, arctic to tropical regions, and inland, coastal, and open ocean waters. Among other hyperspectral satellite sensors, the Environmental Mapping and Analysis Program (EnMAP) provides sufficient sampling bands for the application of TAPIR.

Subject Areas

fluorescence; absorption; chlorophyll-a; remote sensing; hyperspectral; ocean color; IOP; TAPIR; EnMAP

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