Lake Water Quality 2019-2024 (raster 100 m), global, 10-daily - version 1

The Lake Water Quality products provide a semi-continuous observation record for a large number of medium and large-sized lakes, according to the Global Lakes and Wetlands Database (GLWD) or otherwise of specific environmental monitoring interest. 10-daily observations are available in near real time in the spatial resolution of 100 m and and with the temporal extent from 2019 to 2024.

Monitoring water quality in lakes and reservoirs is key in maintaining safe water for drinking, bathing, fishing and agriculture and aquaculture activities. Long-term trends and short-term changes are indicators of environmental health and changes in the water catchment area. Directives such as the EU's Water Framework Directive or the US EPA Clean Water Act request information about the ecological status of all lakes larger than 50 ha. Satellite monitoring helps to systematically cover a large number of lakes and reservoirs, reducing needs for monitoring infrastructure (e.g. vessels) and efforts.

They consist of three water quality parameters: (i) the turbidity of a lake, that describes water clarity or whether sunlight can penetrate deeper parts of the lake. Turbidity often varies seasonally, both with the discharge of rivers and growth of phytoplankton; (ii) the trophic state index that is an indicator of the productivity of a lake in terms of phytoplankton, and indirectly, over longer time scales, reflects the eutrophication status of a water body and (iii) the lake surface reflectances that describe the apparent colour of the water body and are intended for scientific users interested in further development of algorithms. The visual reflectance bands can also be combined into true-colour images.

湖泊水质产品（Lake Water Quality products）依据全球湖泊与湿地数据库（Global Lakes and Wetlands Database, GLWD）或其他具备特定环境监测价值的数据集，为大量中型及大型湖泊提供半连续观测记录。该产品以100米空间分辨率提供近实时的每10天一次观测数据，时间覆盖范围为2019年至2024年。

对湖泊与水库开展水质监测，是保障饮用水、洗浴、渔业、农业及水产养殖用水安全的核心工作。长期变化趋势与短期波动可反映流域环境健康状况及流域内的环境变化。欧盟《水框架指令》（Water Framework Directive）与美国环境保护署（United States Environmental Protection Agency, EPA）《清洁水法》（Clean Water Act）等政策均要求提供所有面积大于50公顷湖泊的生态状况信息。卫星监测能够系统性覆盖大量湖泊与水库，减少对监测基础设施（如船舶）的依赖及监测工作量。

该产品包含三项水质参数：（i）湖泊浊度（turbidity）：用于表征水体透明度或阳光能否穿透湖泊深层水域。浊度通常随季节周期性变化，既与河流径流量相关，也受浮游植物（phytoplankton）增殖的影响；（ii）营养状态指数（Trophic State Index）：该指标基于浮游植物表征湖泊生产力，在较长时间尺度上可间接反映水体的富营养化（eutrophication）状态；（iii）湖泊表面反射率：用于表征水体的表观颜色，面向希望进一步开发算法的科研用户。可见光反射率波段还可合成为真彩色图像。