ISO MODIS NDVI Weekly Composites for Canada South of 60 N Data Product Specification

Transcription

1 ISO MODIS NDVI Weekly Composites for South of 60 N Data Product Specification Revision: A Data specification: MODIS NDVI Composites for South of 60 N - Table of Contents -

2 1. OVERVIEW Informal Description Data product specification metadata Terms and definitions Abbreviations SPECIFICATION SCOPE DATA PRODUCT IDENTIFICATION Data Identification MODIS - Weekly Normalized Composite Maximum MODIS - Weekly Rescaled Normalized Composite Maximum NDVI MODIS Weekly Maximum Baseline NDVI MODIS - Days of the Week Maximum NDVI Weekly Maximum Anomalies DATA CONTENT AND STRUCTURE Feature-based application schema Feature catalogue REFERENCE SYSTEM Spatial reference system Temporal reference system DATA QUALITY Completeness Logical consistency Positional accuracy Temporal accuracy Thematic accuracy Lineage statement DATA CAPTURE DATA MAINTENANCE PORTRAYAL DATA PRODUCT DELIVERY METADATA... 9 Page 2 of 9

3 Data specification: MODIS NDVI Weekly Composites for South of 60 N 1. OVERVIEW 1.1. Informal Description The MODIS NDVI Weekly Composites is a dataset series that provides weekly (7-day) Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) information. The NDVI provides information about the presence and health of vegetation by measuring the type and amount of solar radiation that a location absorbs and reflects. The series were developed by Agriculture and Agri-Food (AAFC) to help monitor 's agricultural landscape in nearreal time. AAFC requires regular, up-to-date information on crop conditions across for crop condition assessment purposes. The dataset series were created by downloading daily MODIS reflectance and quality control data from the U.S. Geological Survey and using it to create a 7-day maximum-ndvi composite for the Canadian landmass and parts of the United States south of latitude 60º N. This composite information provides quality crop condition data for 's agricultural lands. AAFC derives the following datasets from the source MODIS NDVI imagery: Weekly Normalized Composite Maximum, Weekly Resampled Normalized Composite Maximum, Weekly Maximum Baseline, Days of the Week Maximum and Weekly Maximum Anomalies. Currently, the dataset series within the AAFC archives cover the time period from and are updated regularly. The Normalized Difference Vegetation Index (NDVI) is a computationally simple index that can be calculated from the red and near-infrared data acquired by many satellite systems. The NDVI is calculated as NDVI = (NIR - RED)/( NIR + RED), where RED and NIR are the reflected radiant fluxes in the red and near-infrared wavelengths, respectively. The principle behind the NDVI is based on the relationship between the physiological properties of healthy vegetation and the type and amount of radiation it can absorb and reflect. Plant chlorophyll strongly absorbs solar radiation in the red portion of the electromagnetic spectrum, while plant spongy mesophyll strongly reflects solar radiation in the near-infrared region of the spectrum. As a result, vigorously growing healthy vegetation has low red-light reflectance and high near-infrared reflectance, which results in high NDVI values. NDVI output values are between -1.0 and 1.0. Increasing, positive NDVI values indicate increasing amounts of green vegetation. NDVI values near zero and decreasing, negative values indicate nonvegetated surfaces such as barren surfaces (rock and soil) and water, snow, ice, and clouds. Is it important to note that the NDVI is less sensitive to variations in plant chlorophyll for areas with high chlorophyll content. While the NDVI has been shown to accurately indicate many canopy biophysical properties - including vegetation abundance, above ground biomass, green leaf area photosynthetically active radiation (PAR) and productivity results are more general for areas with moderate-to-high quantities of vegetation. Page 3 of 9

4 1.2. Data product specification metadata This section provides metadata about the creation of this data product specification. Data product specification title: Data product specification reference date: Data product specification responsible party: Data product specification language: Data product specification topic category: MODIS NDVI Weekly Composites for South of 60 N Earth Observation Service (EOS) English 1.3. Terms and definitions Feature attribute characteristic of a feature Class description of a set of objects that share the same attributes, operations, methods, relationships, and semantics [UML Semantics] NOTE: A class does not always have an associated geometry (e.g. the metadata class). Feature abstraction of real world phenomena Object entity with a well-defined boundary and identity that encapsulates state and behaviour [UML Semantics] NOTE: An object is an instance of a class. Package grouping of a set of classes, relationships, and even other packages with a view to organizing the model into more abstract structures 1.4. Abbreviations AAFC CAE CCAP DoW EOS MODIS MRT NAIS NDVI NCOM NIR RED RNCOM Agriculture and Agri-Food s agricultural extents Crop Condition Assessment Program Day-of-week Earth Observation Service Moderate Resolution Imaging Spectroradiometer MODIS Reprojection Tool National Agroclimate Information Service Normalized Difference Vegetation Index Normalized Composite Maximum Near-infrared (wavelength) Red (wavelength) Rescaled Normalized Composite Maximum 2. SPECIFICATION SCOPE Page 4 of 9 This data specification has only one scope, the general scope. NOTE: The term specification scope originates from the International Standard ISO Specification scope does not express the purpose for the creation of a data specification or the potential use of data, but identifies partitions of the data specification where specific requirements apply.

5 3. DATA PRODUCT IDENTIFICATION 3.1. Data Identification MODIS - Weekly Normalized Composite Maximum (NCOM) NDVI Alternate MODIS - Weekly Normalized Composite Maximum (NCOM) NDVI The MODIS - Weekly Normalized Composite Maximum (NCOM) NDVI dataset series provides Normalized Difference Vegetation Index (NDVI) information. It describes the presence and health of vegetation using a value between -1 and 1. Data are subject to the Government of : Remote Sensing series MODIS - Weekly Rescaled Normalized Composite Maximum (RNCOM) NDVI Alternate MODIS - Weekly Rescaled Normalized Composite Maximum (RNCOM) NDVI The MODIS - Weekly Rescaled Normalized Composite Maximum (RNCOM) NDVI dataset series provides Normalized Difference Vegetation Index (NDVI) information. It describes the presence and health of vegetation using a value between 0 and 1. Currently, RNCOM data can be queried through the Statistics s Crop Condition Assessment Program (CCAP) web page: Page 5 of 9

6 Data are subject to the Government of : Remote Sensing MODIS Weekly Maximum Baseline NDVI Alternate MODIS Weekly Maximum Baseline NDVI The MODIS Weekly Maximum Baseline NDVI dataset series provides average (mean) values for each cell (250 x 250 m area in the NDVI grid) for a given period of time. It presents average vegetative health for any given week over a specific time period (usually the length of the MODIS record, 13 years in 2012). Data are subject to the Government of : Remote Sensing MODIS - Days of the Week Maximum NDVI Alternate MODIS - Days of the Week Maximum NDVI The MODIS - Days of the Week Maximum NDVI dataset series specifies the day of the week of the reflectance retrieval used to calculate the weekly maximum value in the Normalized Difference Vegetation Index (NDVI) products. Page 6 of 9 Data are subject to the Government of

7 : Remote Sensing MODIS - Weekly Maximum Anomalies NDVI Alternate MODIS - Weekly Maximum Anomalies NDVI The MODIS - Weekly Maximum Anomalies NDVI dataset series compares a given week s NDVI value to a baseline value, which allows any outlier values to be visually compared to average values. Data are subject to the Government of : Remote Sensing 4. DATA CONTENT AND STRUCTURE The MODIS NDVI dataset series are structured using a coverage that represents a time period of seven (7) Julian days. Typically, the data is a single band, 32-bit TIFF coverage Feature-based application schema Not Applicable 4.2. Feature catalogue Not Applicable 5. REFERENCE SYSTEM 5.1. Spatial reference system Horizontal coordinate reference system: WGS 84 Map projection: MODIS Sinusoidal; EPSG:6974 Horizontal coordinate reference system: WGS 84 Map projection: Web Mercator Auxiliary Sphere; EPSG:3857 Page 7 of 9

8 5.2. Temporal reference system Julian calendar 6. DATA QUALITY 6.1. Completeness 6.2. Logical consistency 6.3. Positional accuracy 6.4. Temporal accuracy 6.5. Thematic accuracy 6.6. Lineage statement Lineage Statement Scope The process of generating weekly Normalized Difference Vegetation Index (NDVI) data for involves the following general steps: 1) Ordering and download of MODIS reflectance and quality control data, 2) Extraction of the required datasets from the downloaded MODIS data, 3) Creation of weekly NDVI images, 4) Creation of weekly standard deviation and mean variance images, and 5) Creation of weekly anomalies (difference between NDVI weekly and baseline data) from the Normalized Composite Maximum (NCOM) imagery. 7. DATA CAPTURE The process of generating weekly NDVI images for involves the following three main steps: Page 8 of 9 1. Data Acquisition (ordering and download of MODIS reflectance and quality control data) MODIS LEVEL-2G DAILY GRIDDED DATA PRODUCTS - Manual web query and FTP download of tiles from USGS LPDAAC (a) R and NIR surface reflectance, band QC files (250 m) [MOD09GQK] (b) Surface reflectance state QC file (1 km) [MOD09GST] (c) Geolocation file (1 km) [MODMGGAD] (d) Observation pointer files (250 m, 500 m) [MODPTQKM, MODPTHKM] Input (SIN Projection): Twelve tiles per day per dataset cover s agricultural extents (CAE) Tiles in HDF-EOS format Tile size = Refl. (270MB); QA (9MB); Geo (44MB); 250m, 500m pointers (290MB, 115MB) 2. Data Extraction (extraction of necessary science data sets from the downloaded MODIS data) - USGS MODIS Reprojection Tool (MRT): (a) Reflectance, QC, geolocation and pointer data extracted from each tile (b) Data processed on a tile-by-tile basis 3. Weekly Maximum NDVI Compositing (creation of weekly NDVI images) (a) Daily NDVI calculated from highest-quality R & NIR data (b) Weekly Maximum NDVI is the maximum daily NDVI in the 7-day period

9 (c) Shows which pixels correspond to the day-of-week (DoW) for the Weekly Maximum NDVI image (d) Individual tiles are merged to cover s agricultural extents (CAE) (e) All composites provided in Esri grid format (GeoTIFF, a TIFF 6.0 compliant raster file) 4. Baseline creation (weekly standard deviation and mean variance images) Creates the weekly standard deviation and mean over a given period of time ([Calculation Type].MaxNDVI.[Start Year].[End Year].Week.[Week#]). 5. Anomalies creation (weekly anomalies image) Calculates the weekly anomalies (difference between NDVI normals) from the Normalized Composite Maximum (NCOM) imagery. 8. DATA MAINTENANCE As needed. Max-NDVI products generated weekly for each growing season. Weekly NDVI baselines used in the calculation of anomalies are updated each year to include the additional year s data. 9. PORTRAYAL Not applicable. 10. DATA PRODUCT DELIVERY Delivery medium information: units of delivery: package medium name: online via HTTP, online via direct access Delivery format information: Format name : Tag Interleaved File Version: 6.0 Specification: GeoTIFF is format extension for storing georeference and geocoding information in a TIFF 6.0 compliant raster file by tying a raster image to a known model space or map projection. Languages: eng Character set: utf8 11. METADATA The metadata requirements follow the Government of s Treasury Board Standard on Geospatial Data (ISO 19115). Page 9 of 9