1.5.1.1.7.1.24. polar2grid.readers.viirs_l1b module

The VIIRS Level 1B Reader operates on NASA Level 1B (L1B) NetCDF files.

The files are from the Visible/Infrared Imager Radiometer Suite (VIIRS) instrument. The VIIRS L1B reader analyzes the user provided filenames to determine if a file can be used. Files usually have the following naming scheme (example from the SNPP VIIRS instrument):

VL1BI_snpp_d20160101_t185400_c20160301041812.nc

The VIIRS L1B reader supports all instrument spectral bands, identified as the products shown below. Geolocation files must be included when specifying filepaths to readers and polar2grid.sh. Therefore, the creation of The VIIRS L1B frontend can be specified to the Polar2Grid glue script with the frontend name viirs_l1b.

The list of supported products includes true and false color imagery. These are created by means of a python based atmospheric Rayleigh Scattering algorithm that is executed as part of the Polar2Grid VIIRS L1B reader.

Note

The VIIRS L1B reader only supports the NASA L1B version 2.0 file format. Previous and future versions may work for some products, but are not guaranteed.

This reader’s default resampling algorithm is ewa for Elliptical Weighted Averaging resampling. The --weight-delta-max parameter is set to 40 and the --weight-distance-max parameter is set to 2.

Product Name	Description
i01	I01 Reflectance Band
i02	I02 Reflectance Band
i03	I03 Reflectance Band
i04	I04 Brightness Temperature Band
i05	I05 Brightness Temperature Band
m01	M01 Reflectance Band
m02	M02 Reflectance Band
m03	M03 Reflectance Band
m04	M04 Reflectance Band
m05	M05 Reflectance Band
m06	M06 Reflectance Band
m07	M07 Reflectance Band
m08	M08 Reflectance Band
m09	M09 Reflectance Band
m10	M10 Reflectance Band
m11	M11 Reflectance Band
m12	M12 Brightness Temperature Band
m13	M13 Brightness Temperature Band
m14	M14 Brightness Temperature Band
m15	M15 Brightness Temperature Band
m16	M16 Brightness Temperature Band
DNB	Raw DNB Band (not useful for images)
histogram_dnb	Histogram Equalized DNB Band
adaptive_dnb	Adaptive Histogram Equalized DNB Band
dynamic_dnb	Dynamic DNB Band from Steve Miller and Curtis Seaman. Uses erf to scale the data
hncc_dnb	Simplified High and Near-Constant Contrast Approach from Stephan Zinke
ifog	Temperature difference between I05 and I04
i_solar_zenith_angle	I Band Solar Zenith Angle
i_solar_azimuth_angle	I Band Solar Azimuth Angle
i_sat_zenith_angle	I Band Satellite Zenith Angle
i_sat_azimuth_angle	I Band Satellite Azimuth Angle
m_solar_zenith_angle	M Band Solar Zenith Angle
m_solar_azimuth_angle	M Band Solar Azimuth Angle
m_sat_zenith_angle	M Band Satellite Zenith Angle
m_sat_azimuth_angle	M Band Satellite Azimuth Angle
dnb_solar_zenith_angle	DNB Band Solar Zenith Angle
dnb_solar_azimuth_angle	DNB Band Solar Azimuth Angle
dnb_sat_zenith_angle	DNB Band Satellite Zenith Angle
dnb_sat_azimuth_angle	DNB Band Satellite Azimuth Angle
dnb_lunar_zenith_angle	DNB Band Lunar Zenith Angle
dnb_lunar_azimuth_angle	DNB Band Lunar Azimuth Angle
true_color	Ratio sharpened rayleigh corrected true color
false_color	Ratio sharpened rayleigh corrected false color

For reflectance/visible products a check is done to make sure that at least 10% of the swath is day time. Data is considered day time where solar zenith angle is less than 100 degrees.

class polar2grid.readers.viirs_l1b.ReaderProxy(scn: Scene, user_products: list[str])

Bases: ReaderProxyBase

Provide Polar2Grid-specific information about this reader’s products.

property _aliases: dict[str, DataQuery]

get_all_products() → list[str]

Get all polar2grid products that could be loaded.

get_default_products() → list[str]

Get products to load if users hasn’t specified any others.

is_polar2grid_reader: bool = True

polar2grid.readers.viirs_l1b._process_legacy_products(satpy_names, band_aliases)

Map all lowercase band names to uppercase names and add radiance product.

polar2grid.readers.viirs_l1b.add_reader_argument_groups(parser: ArgumentParser, group: _ArgumentGroup | None = None) → tuple[_ArgumentGroup | None, _ArgumentGroup | None]

Add reader-specific command line arguments to an existing argument parser.

If group is provided then arguments are added to this group. If not, a new group is added to the parser and arguments added to this new group.