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CDOM retrieval using measurements of downwelling irradiance

Linnemann, Kathrin and Gege, Peter and Rößler, Sebastian and Schneider, Thomas and Melzer, Arnulf (2013) CDOM retrieval using measurements of downwelling irradiance. In: SPIE Remote Sensing 2013, 8888, pp. 1-10. SPIE Remote Sensing 2013, 23.-26. Sept. 2013, Dresden, Deutschland.

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Official URL: doi: 10.1117/12.2031250

Abstract

As it can strongly influence the availability of light and thus primary production, coloured dissolved organic matter (CDOM) affects the function of lake ecosystems. Therefore reliable methods are required for the monitoring of CDOM concentration. A new method using downwelling irradiance was tested for applicability in four selected lakes of the Bavarian Osterseen Lake District, which consists of 19 naturally connected freshwater lakes of different trophic level. The method separates between the direct and diffuse part of the incident light in order to handle the strong variability of the underwater light field. It is implemented in the software WASI, which is capable to retrieve water constituents by inverse modeling. During field campaigns downwelling irradiance measurements using RAMSES sensors were made in different depths. Simultaneously, water samples were taken in three depths (0.5 m, 2 m and Secchi disk depth), from which the absorption coefficient of CDOM, aY, was derived in the range from 190 to 900 nm using photometric absorption measurements. Concentration (defined as aY at 440 nm) ranged from 0.33 to 1.55 m-1 ± 0.04 m-1, the spectral slope at 440 nm from 0.0120 to 0.0184 nm-1 with a mean of 0.0145 ± 0.0008 nm-1. These laboratory measurements from water samples were compared to CDOM concentration obtained by inverse modeling of downwelling irradiance measurements using WASI. For sensor depths lower than 1 to 1.5 m large uncertainties were observed. The measurements in 2 m depth and at Secchi disk depth yielded good correlation between water sample and WASI derived data (R^2 = 0.87) with a mean standard deviation of 0.06 m-1 for the determined CDOM concentrations. This new method is an alternative to laboratory analysis of water samples from in situ measurements of CDOM concentration.

Item URL in elib:https://elib.dlr.de/87669/
Document Type:Conference or Workshop Item (Speech)
Title:CDOM retrieval using measurements of downwelling irradiance
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Linnemann, KathrinTU MünchenUNSPECIFIED
Gege, Peterpeter.gege (at) dlr.deUNSPECIFIED
Rößler, SebastianTU MünchenUNSPECIFIED
Schneider, ThomasTUMUNSPECIFIED
Melzer, ArnulfTU MünchenUNSPECIFIED
Date:16 October 2013
Journal or Publication Title:SPIE Remote Sensing 2013
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:8888
Page Range:pp. 1-10
Series Name:Remote Sensing of the Ocean, Sea Ice, Coastal Waters, and Large Water Regions
Status:Published
Keywords:inland waters, monitoring, water constituents, CDOM, downwelling irradiance, RAMSES sensors, inverse modeling, WASI
Event Title:SPIE Remote Sensing 2013
Event Location:Dresden, Deutschland
Event Type:international Conference
Event Dates:23.-26. Sept. 2013
Organizer:SPIE
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Vorhaben Spektrometrische Verfahren und Konzepte der Fernerkundung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Experimental Methods
Deposited By: Gege, Dr.rer.nat. Peter
Deposited On:22 Jan 2014 18:36
Last Modified:31 Jul 2019 19:44

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