This README will serve as a quick reference guide to the MetOp-A ASCAT Scatterometer Inter-Calibrated ESDR Level 2 Ocean Surface Equivalent Neutral Wind Vectors and Wind Stress Vectors Version 1.1 files. These data files are provided in netCDF-4 format using internal compression and adhering to the following metadata standards: ISO-8601, ACDD version 1.3, and CF version 1.8. Each data file corresponds to a specific orbital revolution number, in which the starting point of the file is defined by the beginning of the ascending node of the orbit at the southernmost latitude of the orbit; the ending point of the file is defined by the end of the descending node of the orbit. The following coordinate variables are provided to establish geospatial and temporal placement of data sampled within the swath: time (UTC, expressed in units of seconds since 1999-1-1 00:00:00), lat (latitude, expressed in units degrees), and lon (longitude, expressed in units of degrees in absolute coordinates ranging from 0 to 360).

A brief summary of updates to version 1.1, compared to version 1.0, are summarized as follows:
1) increased data coverage 
2) improved quality control 
3) new global metadata attributes featuring rev number, equator crossing longitude, and equator crossing time (UTC). 

More high-level information about this dataset can be found at the dataset landing page:
https://doi.org/10.5067/ESASA-L2W11

The complete listing of science data variables and associated metadata can be found by executing the following command using your terminal/console: ncdump -h <filename>.nc

The ncdump utility is open-source and is installed by default as part of the netCDF-4 package, which can be obtained here: https://www.unidata.ucar.edu/software/netcdf/

More information on the ncdump utility can be found here: https://www.unidata.ucar.edu/software/netcdf/documentation/NUG/netcdf_utilities_guide.html#ncdump_guide

A quick view (2-D mapped plotting) of the netCDF data and metadata can also be performed through the free and open-source Panoply application, which can be installed on Windows, Mac OSX, and Linux. The latest version of Panoply can be obtained here: https://www.giss.nasa.gov/tools/panoply/

The production of this data is funded by the NASA Making Earth System data records for Use in Research for Earth Science (MEaSUREs) Program through a NASA ROSES-2017 grant. More information on MEaSUREs is here: https://earthdata.nasa.gov/esds/competitive-programs/measures.

A summary of the MEaSUREs proposal for this project has been made available here: https://earthdata.nasa.gov/esds/competitive-programs/measures/esdr-ocean-surface-winds-1999-2022

File naming conventions:
measures_esdr_as_metopa_l2_wind_stress_RRRRR_vN.n_sYYYYMMDD-HHMMSS-eYYYYMMDD-HHMMSS.nc

measures        NASA Program identifier.
esdr                	MEaSUREs product identifier; esdr = Earth System Data Record.
as_metopa      Platform/Instrument Identifier: as = ASCAT; metopa = MetOp-A platform.
l2                  	Processing Level Identifier: l2 = Level 2.
wind_stress     Primary science data variables contained within the Scatterometer product.
RRRRR           5-digit orbital revolution number.
VN.n                Version ID, where N = primary version; n = incremental release number.
s                   	Start date and time separator of the first data in the file in UTC.
e                   	End date and time separator of the last data in the file in UTC.
YYYY              4-digit year in UTC.
MM                  2-digit month in UTC.
DD                  	2-digit day of month in UTC.
HH                  	2-digit hour of 24-hour in UTC.
mm                  2-digit minute of hour in UTC.
.nc                 	File extension: nc = netCDF

Last modified on 9 August 2023.