UFZ-Seminar

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Research Unit

Water Resources and Environment

Programme 2023

Alo Laas, Krista Alikas & Kersti Kangro
(Estonian University of Life Sciences, Tartu, Estonia)

Synergy between in situ and satellite data towards monitoring optically complex waters


Monday, 20 February 2023, 3 p.m.
talk virtually

We will give short overview about field measurements we perform to get an information about optical properties in lakes - a “ground truth” for validation and development of remote sensing algorithms. Estonian lakes are seasonally variable, but in general the majority of light is absorbed by coloured dissolved organic matter and phytoplankton.

Then validation activities, specifically for Copernicus satellites Sentinel-2 MSI and Sentinel-3 OLCI data and analyses of their radiometric and water quality products will be demonstrated. As the global products show poor performance on regional scale, work regarding algorithm development for satellite data over eutrophic and absorbing waters, specifically for estimating phytoplankton (chlorophyll a, phytoplankton biomass, cyanobacterial biomass) and transparency (Secchi depth, diffuse attenuation coefficient) related parameters will be shown. We will also introduce the recently published work “Consistency of six in situ, in vitro and satellite-based methods to derive chlorophyll a in two optically different lakes” (Frontiers in Environmental Science, DOI: 10.3389/fenvs.2022.989671).

And last, if we have more time, Alo can give an overview about the high-frequency monitoring in Estonian lakes and how this contributes to the cooperation with satellite-based Earth Observation, and what are our future plans in that line.

Matthias Mauder
(TU Dresden, Lehrstuhl für Meteorologie)

How well can we quantity evapotranspiration - in general and in particular over open water surfaces?


Monday, 6 March 2023, 3 p.m.
Brückstraße 3a, 39114 Magdeburg, Seminar Room

Evapotranspiration represents the link between the water cycle and the surface energy balance. Accurate knowledge of this key variable is therefore essential to predict the evolution of weather, climate, and ecosystems. One of the most direct methods for measuring evapotranspiration is the eddy-covariance method. However, independent measurements of all relevant component of the surface energy balance indicate a general underestimation of the atmospheric turbulent fluxes. One of the main explanations for the observed general underestimation of turbulent fluxes, is transport by secondary circulations that cannot be captured by single-tower eddy-covariance tower flux measurements. A recently developed semi-empirical model to correct for these additional large-scale dispersive fluxes is now available (De Roo et al. 2018, PLOS One, DOI 10.1371/journal.pone.0209022), and we discuss here the options to apply this new method to real-world long-term flux measurement sites, including the effect for measurements over open water surfaces.
Michael Hügler
(TZW Karlsruhe: DVGW-Technologiezentrum Wasser)

 


Monday, 20 March 2023, 3 p.m.
Brückstraße 3a, 39114 Magdeburg, Seminar Room


Alexander Wacker
(Uni Greifswald)

 


Monday, 17 April 2023, 3 p.m.
Brückstraße 3a, 39114 Magdeburg, Seminar Room

Carsten Simon
(Department of Analytical Chemistry / UFZ)

 


Monday, 18 September 2023, 3 p.m.
Brückstraße 3a, 39114 Magdeburg, Seminar Room


10 January 2023 - UFZ-Magdeburg
Peter Frenzel & Thomas Kasper (Uni Jena)