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NASA SATELLITE DATA FORMATS

NASA SATELLITE DATA FORMATS. Ana I. Prados, UMBC/JCET Steve Lloyd, Wyle Information Systems, Inc. AMS Giovanni Short Course January 11 th , 2009 . NASA Satellite Data. Formats in which the data are available Spatial resolution of the data

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NASA SATELLITE DATA FORMATS

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  1. NASA SATELLITE DATA FORMATS Ana I. Prados, UMBC/JCET Steve Lloyd, Wyle Information Systems, Inc. AMS Giovanni Short Course January 11th, 2009

  2. NASA Satellite Data • Formatsin which the data are available • Spatial resolutionof the data • Level of Processingof the data • Versions of the data • How to access datain various formats at the NASA GES DISC

  3. Data Formats • Text/ASCII pros: easy to read and examine the data right away (can read with used tools such as excel and GIS software) cons: large data files • Binary – HDF, NetCDF pros: takes less space, more information (metadata,SDS) cons: need specific tools or code to read the data • KML or KMZ (zipped KML) pros - easy 2D and 3D visualization of the data through free tools such as Google Earth. Data are very low volume

  4. Spatial Resolution of NASA Satellite Data Products • High Spatial resolution • 250x250m; 500x500 m; 1x1 km; 0.05x0.05 degrees • Example: MODIS True Color Imagery (RGBs) • Moderate Spatial Resolution • 0.25x0.25 degrees • Example: OMI Tropospheric NO2 (Giovanni and NASA • AVDC); TRMM precipitation products. • Giovanni Data Products • Primarily at 1x1 degree resolution (derived from each • data set’s native resolution product). • Example: AIRS surface air temperature

  5. Example of NASA High Spatial Resolution Product 2x2 km resolution MODIS TERRA True Color Image over Southern California January 4th, 2009 Source:NASA GSFC Rapidfire AERONET Subset for Fresno, CA

  6. Example of NASA Moderate Spatial Resolution Product (KMZ format) 0.25x0.25 degree OMI NO2 KMZ data format Eastern China (image saved from Google Earth) September 1st, 2008 Source:NASA Giovanni

  7. Example of NASA Moderate Spatial Resolution Product (KMZ format) 0.25x0.25 degree OMI NO2 KMZ data format Eastern China (image saved from Google Earth) September 1st, 2008 Source:NASA Giovanni

  8. 1x1 degree product (from data file in HDF format) 1 x 1 degree MODIS Aqua Aerosol Optical Depth Giovanni generated GIF image (from HDF data file) October 24th, 2007 Source:NASA Giovanni

  9. Levels of Data Processing

  10. Levels of Data Processing and Spatial Resolution • Level 1 and Level 2data products have the highest spatial and temporal resolution • Level 3 productsare derived products with equal or lower spatial and temporal resolution than Level 2 products

  11. Levels of Data Processing: L2 (Level 2) Tropospheric NO2 (Swath Data) Plotted from HDF data file Grid is irregular (pixels are larger – lower resolution at swath edge) Eastern China September 1st, 2008 Source:NASA GES DISC

  12. Levels of Data Processing: L2G Tropospheric NO2 (Gridded Data) 0.25x0.25 degree L2G OMI NO2 KMZ data format. Eastern China (image saved from Google Earth). September 1st, 2008 Source:NASA Giovanni

  13. Levels of Data Processing: L3 (Level 3) TRMM 10-Day Rainfall 0.25x0.25 degree TRMM rainfall (some datasets can be recalculated) Temporally averaged Global Map November 1-10, 2008 Source:NASA Giovanni

  14. Data Versions • For each level of processing versions of data are periodically released as retrieval algorithms or other sources of information improve, e.g. V001, V002, V003 • For some GES DIS products more than one version may be available • Note: Giovanni products are the most recent data version publicly available

  15. Accessing different data formats(Example: Giovanni Download Page) GIF KMZ HDF Net CDF ASCII

  16. Putting it all together: data file names OMI-Aura_L2G-OMNO2G_2009m0102_v003-2009m0103t171930.he5 Data product (OMI L2G Tropospheric NO2) Time (hour minute, second) Date (1/2/09) Version (version 3) Processing Date (1/3/09) Data Format (HDF5) Data format is HDF5 Level of Processing is L2G Version 3 Source:GES DISC

  17. Conclusions • NASA satellite data formats are varied and the most appropriate depends on specific user needs • Available data formats include, ASCII, HDF, NetCDF, and KMZ • Satellite data vary in spatial resolution depending on instrument characteristics and the level of processing (L2, L2G, L3). The standard Giovanni resolution is 1x1 degrees. Re-gridding services and a few products allow access to other spatial resolutions

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