Download presentation
Presentation is loading. Please wait.
Published byAlvin Short Modified over 8 years ago
1
WSL Workshop The Long and Winding Road to MODIS Data
2
WSL Workshop MODIS Land Products MODIS Land Products – Quick review MODIS Land Products Web Sites – Where to get specifics on land products
3
WSL Workshop MODIS Land Products Ecosystem Variables Vegetation Indices (NDVI & EVI) Leaf Area Index (LAI) and Fraction Photosynthetically Active Radiation (FPAR) Vegetation Production, Net Primary Productivity (NPP) Land Cover Characteristics Fire and Thermal Anomalies Land Cover Vegetation Cover Conversion Vegetation Continuous Fields At-Launch Land Cover (derived from AVHRR) Radiation Budget Variables Surface Reflectances Land Surface Temperature (LST) and Emissivity Snow and Ice Cover Bi-directional Reflection (BRDF) and Albedo
4
WSL Workshop ProductSpatial ResolutionTemporal Resolution (MOD09) Land Surface Reflectance500m8 day composite 7 band product (MOD10) Snow Cover500mdaily, 8-day, monthly (MOD12) Land Cover Type/Change1 kmat-launch, quarterly (MOD13) Vegetation Indices250m*, 500m, 1km16-day, monthly (MOD15) LAI/FPAR1km8-day (MOD17) Vegetation Productivity1km8-day MODIS Land Products Available Resolutions note: not all products are currently available
5
WSL Workshop http://modarch.gsfc.nasa.gov Land
6
WSL Workshop
8
Algorithm Technical Basis Document PI Web Site
9
WSL Workshop PI Web Sites LOOK FOR “User’s Guide”
10
WSL Workshop The MODIS Web Organigram Direct to PI Websites EOS DataGateway Land Validation Home Site
11
WSL Workshop MODIS Land Products MODIS Data Processing What’s up with L1, L2, L3, L4 Data ??
12
WSL Workshop MODIS Land Products The amount of processing performed by NASA for MODIS Land Application Products has never been applied for publicly distributed data.
13
WSL Workshop
17
Level 1B = Raw, Un-calibrated Swath Data (Scene), Not projected = Includes radiometric and calibration coefficients and parameters, but not applied Level 2 = Derived geophysical variables at the same resolution and location as the Level 1 source data Level 2G = Calibrated, IS Map Projection*, Tiled = Multiple Coincident Swaths (e.g. overlapping pixels) *Integerized Sinusoidal Level 1 - Level 4 Data
18
WSL Workshop Level 3 Data = Variables mapped on uniform space-time grid scales = “MODIS Land End User” = Usually composite data = Tiled, IS Projection, “Best” pixel selection (e.g. one value/pixel) Level 4 Data = Model output or results from analysis of lower level data = LAI/FPAR, PSN/NPP Level 1 - Level 4 Data
19
WSL Workshop MODIS Land Tile Structure Integerized Sinusoidal (IS) Projection Referenced by horizontal and vertical position h18v04 h19v04
20
WSL Workshop MODIS Land Tile Structure Integerized Sinusoidal (IS) Projection Referenced by horizontal and vertical position IS Projection 1 km tile = 1200 x 1200 500 m tile = 2400 x 2400 250 m tile = 4800 x 4800
21
WSL Workshop MODIS Land Tiles for U.S. Lambert Azimuthal Equal Area
22
WSL Workshop Relationship of MODIS tiles to TM scenes
23
WSL Workshop MODIS Land Products Obtaining MODIS (Terra, EOS) data
24
WSL Workshop Data are available from eight EOSDIS Distributed Active Archive Centers (DAACs), two affiliated datacenters, and a growing number of international partners. Data centers process, archive, and/or distribute EOS and other NASA Earth Science data, and provide full support to users of these data. Each data center holds and provides data pertaining to a particular Earth science discipline. Collectively provide a physically distributed but logically integrated database. Obtaining MODIS (Terra, EOS) data
25
WSL Workshop Distributed Active Archive Centers (DAACs)
26
WSL Workshop The Good News The EOS Data Gateway (http://eos.nasa.gov/imswelcome) Single point of entry for multiple Distributed Active Archive Centers (DAACs) Data and documentation Wide variety of search parameters –Location, Time period, Sensor, Product, Quality Can save queries for later use Good tutorial
27
WSL Workshop
31
Granule ID MOD13A1.A2000161.h18v04.002.2000203002556.hdf MODXXX.Ayyyyddd.hxxvxx.vvv.yyyydddhhmmss.hdf MODXXX = product and level of product A = Terra (formally known as EOS-AM1) yyyyddd = year and year day (001 – 366) for the start of the granule hxxvxx = MODIS land tile vvv = a three-digit version number assigned by ECS yyyydddhhmmss = 4 digit year, 3 digit day, hr, min, and sec of the time (UTC)at which the granule is processed.
32
WSL Workshop The BAD News HDFEOS File Formats Integerized Sinusiodal Projection
33
WSL Workshop MODIS Land Tile Structure Integerized Sinusoidal (IS) Projection approx. 10 x 10 (1200 x 1200, 1km tile) No common RS/GIS software supports this projection (yet). We will work with software developed at NTSG (P. Thornton and J. Glassy)
34
WSL Workshop HDF Files HDF = Hierarchical Data Format Developed by the National Center for Supercomputing HDF = Features include platform independence, user extendibility, and embedded metadata for units, labels, and other descriptors. HDF = Standard data types include: multidimensional array, text, table, raster image, and palette (all packaged into 1 file). HDF = Structures of different resolutions can be stored in the same file.
35
WSL Workshop HDF-EOS Files HDFEOS = Standard HDF with ECS (EOSDIS Core System) conventions, data types, and metadata added. HDFEOS = ECS core metadata is essential for search services. HDFEOS = Read by any tool that processes standard HDF files, although HDFEOS geolocation and temporal information generally is not accessible.
36
WSL Workshop HDF-EOS Files Objects: Grids (Swaths and Points) Science Data Fields (SDS): 2D+ arrays Coded biophysical values (8 - 16 bit) Defined Projection Metadata QC Fields (for each grid) Per pixel quality codes Tile Level Metadata
37
WSL Workshop The Good News Many tools currently exist or are being developed that will read the hdfeos file format. Current Tools Hdflook Webwinds IDL/ENVI extensions NOESYS http://hdfeos.gsfc.nasa.gov/hdfeos/workshop.html http://www-loa.univ-lille1.fr/Hdflook/hdflook_gb.html http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/MODIS/index.html
38
WSL Workshop
40
Data Flows 1) Search and download data in HDF format (EOS Data Gateway) 2) Extract data and metadata from HDF files (HDFLook, IDL/ENVI, future tools) 3) Project from Integerized Sinusoidal to lat/long or other supported projection (? Custom program, future tools) 4) Import raw binary rasters into GIS/RS package 6) Tile or subset rasters 5) Decode raster values into physical units GIS/RS Package Arc/Info ArcView Imagine
41
WSL Workshop And the Result !
42
WSL Workshop A little bit about Metadata The metadata text file that is posted with the hdf file is generally meant for sophisticated queries of EOS data. The hdf file has embedded metadata that the “user” will generally find more meaningful. Read through tools that read hdfeos files. MOD13A1.A2000161.h18v04.002.2000203002556.hdf.met
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.