N: 66 S: -66 E: 180 W: -180
Description
The Global Lake/Reservoir Surface Inland Water Height Time Series is derived from the G-REALM10 lake level product https://ipad.fas.usda.gov/cropexplorer/global_reservoir/ The purpose of this dataset is to provide surface water dynamics for several hundred lakes and reservoirs across the globe. These time series potentially span a 25 year time period, from late 1992 to 2017, satisfying the project goal of ESDR creation with a suitable level of quality that supports long-term trend analysis and global water dynamics models. Water level variation is also a key component required for the determination of surface water storages and fluxes. This product is readily accessible and is of direct use to both water managers and the scientific community worldwide, and allows for improved assessment and modeling of the human impact on the global water cycle. These pre SWOT data are derived from satellites to provide hydrological measurements. The Surface Water and Ocean Topography (SWOT) mission will have hydrology as one of its objectives. This dataset does not have the same variables as SWOT, but does provide hydrological measurements with typical quality flagging typical of satellite data. Not only does it provide science information, it can also assist hydrological users new to satellite data with the satellite data formats and variables before SWOT launches.
Product Summary
Citation
Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.
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DATA CITATION GUIDELINES
Variables
Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.
The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.
| Name Sort descending | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor |
|---|---|---|---|---|---|---|
| altimeter_source | Flag to identify the data source from G-REALM10, G-REALM35, DAHITI, or Hydroweb | N/A | int | -999 | N/A | 1 |
| ice_flag | Flag to indicate ice presence on a monthly basis. This flag was determined using a combination of bibliographical resources and MODIS data (MOD10A1.005) in Google Earth Engine. For the MODIS derived ice dates the Bitmask for Snow_Cover_Daily_Tile (100: Snow Covered Lake Ice) on the Terra Snow Cover Daily Global 500m product was used. A ratio was made using cumulative monthly ice coverage per lake and lake surface area. If the monthly ice cover for each lake exceeded half of the maximum ice coverage for the range of the product the lake the data was flagged. Bibliographical data was selected preferentially over MODIS derived data. Due to the spectral confusion between ice with high turbidity and algal blooms, lakes that were highly turbid or had high chlorophyllic activity in areas that do not freeze were hand edited. | N/A | int | -999 | N/A | 1 |
| outlier_flag | Flag to indicate statistical outliers | N/A | int | -999 | N/A | 1 |
| surface_water_height | The Global Lake/Reservoir Surface Water Height Time Series is derived from the NASA/USDA G-REALM 10-day, G-REALM 35-day, as well as LEGOS and DAHITI lake level products. Data Processing Version ID for G-REALM 10-day product: TPJOJ.2.3 | m | float | -999 | -1.13 to 0.56 | 1 |
| time | The provided date indicates the beginning of the time stamp. Altimeter data is acquired from different agencies and merged together. Therefore, the altimeter data has variable temporal resolution and is dependent upon which data source was used (see variable altimeter_source). | days since 1900-01-01T00:00:00 | int | N/A | N/A | 1 |