1 / 14

GGSPS Data

GGSPS Data. How to access data How to read data. GGSPS Level 1.5 NANRG and ARG filtered radiances Level 2 ARG fluxes and unfiltered radiances from RGP (40 day delay) ROLSS Level 2 ARG, BARG, SHI fluxes and unfiltered radiances (< 40 days). GGSPS or ROLSS ?. Access to GGSPS Data.

gad
Download Presentation

GGSPS Data

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GGSPS Data How to access data How to read data

  2. GGSPS Level 1.5 NANRG and ARG filtered radiances Level 2 ARG fluxes and unfiltered radiances from RGP (40 day delay) ROLSS Level 2 ARG, BARG, SHI fluxes and unfiltered radiances (< 40 days) GGSPS or ROLSS ?

  3. Access to GGSPS Data http://ggsps.rl.ac.uk/ Registration: Controlled by Imperial.

  4. Access to GGSPS Data “Catalogue”: Catalogue searches only several search criteria “Products”: Catalogue searches and retrieval of products

  5. Access to GGSPS Data

  6. Three ways to download products: click on link to an individual file click on “Download” button maximum limit of 600 files “Access the most recent data products” (from the “Products” page) … tarred and zipped products in 6 hour bundles. Downloading Products

  7. L1.5 NANRG and ARG Products NANRG (6 individual unrectified images) up to 6 radiance datasets (256 x 282) up to 6 longitude and 6 latitude datasets ARG (2 time averaged rectified images) 2 radiance, 2 standard dev, 2 valid. flag datasets 1 longitude, 1 latitude, 3 viewing angle datasets HDF5 Format (Hierarchical Data Format) Structure of Products

  8. Three entities to know about: Groups: rather like directories, define a hierarchy within which the data is stored Datasets: tend to hold one or two dimensional arrays of data. Has an associated “dataspace”. Attributes: tend to hold individual values, sometimes one dimensional arrays, of metadata. Groups and datasets can both have attributes. HDF5 Files

  9. NANRG GroupsDatasetsAttributes

  10. ARG GroupsDatasetsAttributes

  11. Datasets • Usually signed short integers • Written out row by row (north-> south); each row west-> east • use quantisation factor attribute to convert data to correct units: Converted value = encoded value * quantisation factor

  12. HDF5 tools (h5dump, h5ls, H5View) useful for seeing what’s in an unknown file IDL IDL v5.6+ (or v5.5 & plug-in) : HDF5 <= v5.5 : HDF4 only. Use h5toh4 to generate HDF4 GERB products. bugs in h5_browser/h5_parse HDF APIs write your own Fortran/C/C++/Java/… code How to read products

  13. Example (IDL HDF5 interface) FILE_ID = H5F_OPEN(FileName) ; open file ; open root and radiometry groups root_group_id = H5G_OPEN(FILE_ID,ROOT_GROUP) radiometry_group_id = H5G_OPEN(root_group_id,RADIOMETRY_GROUP) ; open and read the dataset SW1_ID = H5D_OPEN(radiometry_group_id,SW_1) SW1Data = H5D_READ(SW1_ID) ; open and read the quantisation factor attribute ATT_ID = H5A_OPEN_NAME(SW1_ID,QUANTISATION_FACTOR) SW1_QF_Data = H5A_READ(ATT_ID) H5A_CLOSE, ATT_ID ; close attribute and dataset H5D_CLOSE, SW1_ID H5G_CLOSE, radiometry_group_id ; close groups H5G_CLOSE, root_group_id H5F_CLOSE, FILE_ID ; close file

  14. Example Code and Simple Tools on GGSPS Web Site (see “Products” page) GGSPS User Guide will appear shortly RMIB User Guide available (more info on how to read HDF files) NCSA HDF Web Site http://hdf.ncsa.uiuc.edu/ libraries, tools, tutorial, user guide, reference manual Further Help

More Related