1. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 1 HDF-EOS Aura File Format Guidelines Cheryl Craig September 20, 2000

2. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 2 Preliminary Aura Data System Working Group will meet in October to discuss and hopefully adopt Authors from each instrument team are in agreement

3. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 3 What Is Aura? Third in series of EOS atmospheric chemistry satellites (1:45 PM equator crossing time) Formerly known as CHEM To be launched June 2003 Level 2 data products include: –Vertical profiles of temperature, pressure, chemical and aerosol species –Column amounts of chemical species –Cloud properties

4. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 4 Aura Instruments HIRDLS (High Resolution Dynamics Limb Sounder) –Limb infrared sounder –University of CO and Oxford MLS (Microwave Limb Sounder) –Limb microwave sounder –JPL OMI (Ozone Monitoring Instrument) –Nadir wide-field-imaging spectrometer –Netherlands, Finland and US TES (Tropospheric Emission Spectrometer) –Nadir and limb infrared-imaging spectrometer –JPL All instruments have world-wide co-investigators

5. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 5 Why Guidelines for Aura Instruments? HDF-EOS Swath allows a lot of flexibility Ease cross-platform use of Aura files –Ease development of software –Easier to understand Intended to standardize Level 2 files (may apply to Level 3 and above as well)

6. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 6 Areas of Potential Mismatch Organization of data fields and attributes Dimension names Geolocation names and dimension ordering Data field names and dimension ordering Units for data fields Attribute names, values and units

7. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 7 Guidelines List Instrument teams will use the same major version of HDF-EOS Aura Level 2 files will use HDF-EOS Swath HDF-EOS structure names will strictly adhere to Valids list Data will be reported on a pressure grid and be ordered from ground to space

8. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 8 Guidelines List (continued) Data fields will be ordered with pressure coordinate being the fastest incrementing coordinate Data fields will be in units specified HDF fill value and MissingValue will have the same value Instrument data fields unique to particular instrument will be prefixed with instrument name

9. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 9 Swathname: Meas. Species Name Dimensions: nTimes nLevels etc. Geolocation Fields: Time Latitude etc. Data Fields: L2gpValue L2gpPrecision Global Attributes: Instrument Name Process Level etc. Swathname: Instrument Name Dimensions: nTimes nLevels etc. Geolocation Fields: Time Latitude etc. Data Fields: Temperature O3 etc. Global Attributes: Instrument Name Process Level etc. Organization of Data Fields and Attributes Type 1Type 2 HDF-EOS V3.x Note – Two types may be merged into one using links for Data Field Names

10. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 10 Standard Names Adhere to strict names (spacing and capitalization required) Dimension names Geolocation Fields – Used to hold descriptor data (includes SolarZenithAngle, OrbitAscendingFlag, etc.) Data Fields – Contains measured and derived data Global Attributes – Includes InstrumentName and ProcessLevel Data Field Attributes – only if use HDF-EOSV3 (includes MissingValue, ScaleFactor, Units, etc.)

11. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 11 HDF-EOS V2.x Versus V3.x HDF-EOS V2.x PROS Currently used by Terra and Aqua teams Currently available CONS Based on HD4 – supported by HDF group in maintenance only mode HDF-EOS V3.x PROS Contains new functionality –local data attributes –more than one unlimited dimension –compression with unlimited dimensions Based on HDF5 CONS IDL support (unknown?) Aura will decide at future date. At January, 2000 DSWG, indicated desire to used V3.x if packages like IDL will be available in V3.x

12. HDF-EOS Aura File Format Guidelines Cheryl Craig HDF-EOS Workshop IV Sept 20, 2000 12 Conclusions Preliminary standardization complete – meeting in October to discuss and adopt HDF-EOS version decision to be decided at a future date Some decisions postponed until prototyping efforts complete Standard may evolve as instrument teams get better understanding of their data storage needs URL of document: http://www.eos.ucar.edu/hirdls/HDFEOS_Aura_File_Format_Guidelines.pdf

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