Tunisie site 1 ndwi 2015 to 2026

README - Tunisie site 1 NDWI dataset File name---------tunisie_site_1_ndwi_2015_2026.xlsx Short description-----------------This file contains a Sentinel-2 Normalized Difference Water Index (NDWI) time series for the Tunisie site 1 location. Data source-----------Source product: Sentinel-2 imagery used through WESAT / Google Earth Engine.WESAT dataset identifier: sentinel2Exact Google Earth Engine collection ID: not encoded in this API response; confirm it from the original WESAT job/configuration.Sentinel-2 Level-1C Harmonized reference: https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_S2_HARMONIZEDSentinel-2 Level-2A SR Harmonized reference: https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_S2_SR_HARMONIZEDProducer: European Union / ESA / CopernicusGoogle Earth Engine API reference: https://developers.google.com/earth-engine/reference/restWESAT platform: https://wesat.wascal.org/Source verification/access date for this README: 2026-09-21 Important source note---------------------The WESAT JSON identifies the dataset generically as 'sentinel2' but does not store the exact Earth Engine collection ID, preprocessing chain, cloud-mask rule, reducer or pixel scale. This exporter therefore records both common Harmonized Sentinel-2 catalog references without claiming which one produced the response. Archive the original WESAT job or extraction configuration for exact reproducibility. Location / spatial coverage---------------------------Location label used in the file name: tunisie_site_1Country/context: TunisiaSpatial extraction geometry: Polygon stored in the original WESAT API response. Variable--------Workbook column: NDWI (unitless)Variable: Normalized Difference Water Index (NDWI)Unit: DimensionlessPurpose/formula details should be confirmed from the WESAT implementation or original extraction configuration when required for publication. Temporal frequency------------------Nominal Sentinel-2 revisit: approximately 5 days.Frequency in this Excel file: Irregular acquisition-date series (median interval 5 days; most common interval 5 days).Covered period: 2015-07-04 to 2026-09-16Number of records: 741 Aggregation / extraction status-------------------------------NDWI is a derived spectral index. Each row corresponds to one retained WESAT/Sentinel-2 observation timestamp.No temporal averaging is applied by this exporter. The scalar values are copied from the WESAT JSON response.The API response alone does not establish whether each scalar is a point/pixel value or a spatial reducer over the polygon. Extraction method-----------------According to the project workflow, the data were obtained through WESAT, which wraps Google Earth Engine functionality. General workflow:1. Select Sentinel-2 imagery for the target area.2. Filter imagery to the requested period.3. Apply the preprocessing configured in WESAT/GEE.4. Compute or retrieve the requested NDWI index.5. Extract one scalar value for each retained observation.6. Export the resulting time series to Excel. Recommended reproducibility information to archive with this file------------------------------------------------------------------ Original WESAT JSON response: tunisie_site_1_ndwi_2015_2026.json- Exact coordinates/polygon stored in the API response.- Google Earth Engine collection ID actually used by the WESAT job.- Sentinel-2 bands/index formula used.- Cloud filter and/or cloud-mask method.- Spatial reducer, requested scale and projection.- WESAT job identifier or extraction script/version.- Extraction/export date and operator. Quality and interpretation notes--------------------------------These are derived satellite spectral-index values, not direct field measurements.The exported dates are based on observations actually present in the JSON response. The requested API range can be broader than the period with available Sentinel-2 observations.The exporter preserves all valid observations, sorts them chronologically, and warns rather than silently deleting duplicate/invalid records. File structure--------------Workbook sheet name: Sheet1Columns:- Date: Sentinel-2 acquisition/observation date in YYYY-MM-DD format when one observation occurs per day.- NDWI (unitless): extracted NDWI value for the selected location. Prepared for------------WASCAL data preparation workflowREADME prepared on: 2026-09-21Prepared by: Dr Belko Abdoul Aziz DIALLO