Day 4

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Paper title Near-real time observations of Lake Surface Water Temperature using Sentinel 3A/3B data for Copernicus Global Land Service (CGLOPS)
  1. Laura Carrea University of Reading Speaker
  2. Ross Maidment University of Reading
  3. Christopher Merchant University of Reading
Form of presentation Poster
  • A5. Climate
    • A5.02 The role of Earth Observation in climate services
Abstract text Lake surface water temperature (LSWT), which describes the temperature of the lake at the surface, is a recognised Essential Climate Variable (ECV) of the Global Climate Observing System (GCOS). It is one of the key parameters determining the ecological conditions within a lake, since it influences physical, chemical and biological processes. LSWT also plays a key component in the hydrological cycle, determining both air-water heat and moisture exchanges. As such, monitoring LSWT globally can be extremely valuable in detecting localised climatic extremes, forewarning authorities to the potential impact of such events on lake ecosystems. But also, operational LSWT observations have potential environmental and meteorological applications for inland water management and numerical weather prediction (NWP) through assimilation.

Through the Copernicus Global Land Surface (CGLOPS) project, we have developed and operationalised a global LSWT dataset that provides a thermal characterization of over 1000 of the world’s largest lakes. The operational LSWT product is generated from brightness temperatures observed by the SLSTR instruments onboard Sentinel3A and Sentinel3B. The dataset is currently based on SLSTR Sentinel3A since June 2016 and both SLSTR Sentinel3A and SLSTR Sentinel3B since August 2020.

LSWT is delivered every 10 days, the period covered starting the 1st, 11th and 21st day of each month and providing a 10-day LSWT average along with uncertainty and quality levels. The LSWTs are mapped to a regular grid of about 1 km resolution. The data are routinely available through the CGLOPS data portal with a latency of three days. As part of the routine monitoring of the product, plots showing comparisons of the most recent LSWT against its climatology for each lake are updated together with the spatial distribution of the LSWTs, allowing for easy detection of anomalous events. Another important aspect of the monitoring is the timeliness and the completeness of the SLSTR data at the time of processing. As such, plots showing the completeness of each 10-day product are made available to show users the amount of data that has been used to generate each product. The LSWTs are regularly validated against in situ measurements covering a large portion of the globe. A simple, interactive web-based platform ( has been developed to assist with the exploitation of the near-real time information for each lake covered by the CGLOPS LSWT product and reports detailed information on the validation of the product.