DOI: 10.1594/pangaea.871462
title: Diversity II water quality parameters for 300 lakes worldwide from ENVISAT (2002-2012)

description: The use of ground sampled water quality information for global studies is limited due to practical and financial constraints. Remote sensing is a valuable means to overcome such limitations and to provide synoptic views of ambient water quality at appropriate spatio-temporal scales. In past years several large data processing efforts were initiated to provide corresponding data sources. The Diversity II water quality dataset consists of several monthly, yearly and 9-year averaged water quality parameters for 340 lakes worldwide and is based on data from the full ENVISAT MERIS operation period (2002–2012). Existing retrieval methods and datasets were selected after an extensive algorithm intercomparison exercise. Chlorophyll-a, total suspended matter, turbidity, coloured dissolved organic matter, lake surface water temperature, cyanobacteria and floating vegetation maps, as well as several auxiliary data layers, provide a generically specified database that can be used for assessing a variety of locally relevant ecosystem properties and environmental problems. For validation and accuracy assessment, we provide matchup comparisons for 24 lakes and a group of reservoirs representing a wide range of bio-optical conditions. Matchup comparisons for chlorophyll-a concentrations indicate mean absolute errors and bias in the order of median concentrations for individual lakes, while total suspended matter and turbidity retrieval achieve significantly better performance metrics across several lake-specific datasets. We demonstrate the use of the products by illustrating and discussing remotely sensed evidence of lake-specific processes and prominent regime shifts documented in the literature.
description: Over ten years, the European Space Agency operated the largest Earth observation satellite built to date, ENVISAT. Its instruments provided optical and thermal observations, and allowed for retrieval accuracies not previously achieved by spaceborne remote sensing. Using these observations, we created a comprehensive database consisting of water quality parameters for more than 300 lakes in the whole World. The Diversity II inland water database is designed to meet the requirements of the aquatic biodiversity community, but represents beyond this purpose the first globally consistent and reproducible knowledge basis of its kind.We processed various water quality parameters and adopted lake surface water temperature from the ESA ARC Lake database. Monthly, yearly and a 9-year aggregated geophysical maps are provided. The potential of these products is demonstrated in the context of several case studies, wherein local experts assess the information content against the background of issues such as eutrophication and hypoxia, floating vegetation proliferation and the occurrence of cyanobacteria blooms. Qualitative links are established between those phenomena and biodiversity trends.File format is geotif. Minimal granularity is one geotif per month in zip archives per year. All 11 zip archives (2002-2012) of one lake are combined with the lake's annual and 9-year averaged zip archives in one *.7z archive. The table lists metadata and basic data of the 343 lakes with links to the *.7z archives. File size is between 100 kB and 20 GB.Legend for GLWD Use1, 2 and 3: c flood control, f fish breeding, h hydropower, i irrigation, n navigation, r recreation, s water supply, x others
description: Supplement to: Odermatt, Daniel; Danne, Olaf; Philipson, Petra; Brockmann, Carsten (2018): Diversity II water quality parameters from ENVISAT (2002–2012): a new global information source for lakes. Earth System Science Data, 10(3), 1527-1549