The data and resulting data products (tables, figures and maps) available on the indicator web page can be used freely given that the source is cited. The indicator should be cited as following:
HELCOM (2018) Water clarity. HELCOM core indicator report. Online. [Date Viewed], [Web link].
Result: Water Clarity
Data source: The average for 2011-2016 was estimated using monitoring data provided by the HELCOM Contracting Parties, and kept in the HELCOM COMBINE database, hosted by ICES (www.ices.dk). Nominated members of HELCOM STATE & CONSERVATION group were given the opportunity to review the data, and to supply any missing monitoring observations, in order to achieve a complete dataset.
Description of data: The data includes secchi depth measurements explained in the HELCOM COMBINE manual.
Geographical coverage: The observations are distributed in the sub-basins according to the HELCOM COMBINE programme, added occasionally with data from research cruises.
Temporal coverage: The raw data includes observations throughout the year, during the assessment period 2011-2016.
Data aggregation: The 2011-2016 averages for each sub-basin were produced as an inter-annual summer (June – September) estimates.