4.1. VIIRS SDR Reader

The VIIRS SDR Reader operates on Science Data Record (SDR) HDF5 files from the Suomi National Polar-orbiting Partnership’s (NPP) and/or the NOAA20 Visible/Infrared Imager Radiometer Suite (VIIRS) instrument. The VIIRS SDR reader ignores filenames and uses internal file content to determine the type of file being provided, but SDR are typically named as below and have corresponding geolocation files:

SVI01_npp_d20120225_t1801245_e1802487_b01708_c20120226002130255476_noaa_ops.h5

The VIIRS SDR reader supports all instrument spectral bands, identified as the products shown below. It supports terrain corrected or non-terrain corrected navigation files. Geolocation files must be included when specifying filepaths to readers and polar2grid.sh. The VIIRS reader can be specified to the polar2grid.sh script with the frontend name viirs_sdr.

Note

This reader used to be named “viirs”. Both “viirs_sdr” and “viirs” will work when passed to polar2grid.sh, but in future versions only viirs_sdr will be supported. The name viirs_l1b is the only way to access the VIIRS L1B Reader.

This reader’s default remapping algorithm is ewa for Elliptical Weighted Averaging resampling. The --fornav-D parameter set to 40 and the --fornav-d parameter 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
i01_rad	I01 Radiance Band
i02_rad	I02 Radiance Band
i03_rad	I03 Radiance Band
i04_rad	I04 Radiance Band
i05_rad	I05 Radiance 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
m01_rad	M01 Radiance Band
m02_rad	M02 Radiance Band
m03_rad	M03 Radiance Band
m04_rad	M04 Radiance Band
m05_rad	M05 Radiance Band
m06_rad	M06 Radiance Band
m07_rad	M07 Radiance Band
m08_rad	M08 Radiance Band
m09_rad	M09 Radiance Band
m10_rad	M10 Radiance Band
m11_rad	M11 Radiance Band
m12_rad	M12 Radiance Band
m13_rad	M13 Radiance Band
m14_rad	M14 Radiance Band
m15_rad	M15 Radiance Band
m16_rad	M16 Radiance 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

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 the solar zenith angle is less than 100 degrees.

Note

Terrain corrected geolocation for the DNB band has recently been added and is included in the non-TC file (GDNBO). This may cause some confusion to users as the VIIRS SDR reader currently only checks for terrain corrected data. To use non-TC data use the --no-tc flag (described below).

4.1.1. Command Line Arguments

usage: polar2grid.sh viirs_sdr <writer> [-h] [--list-products] [--no-tc]
                                        [--day-fraction DAY_FRACTION]
                                        [--night-fraction NIGHT_FRACTION]
                                        [--sza-threshold SZA_THRESHOLD]
                                        [--dnb-saturation-correction]
                                        [-p PRODUCTS [PRODUCTS ...]]
                                        [--adaptive-bt] [--i-bands]
                                        [--m-bands] [--dnb-angle-products]
                                        [--i-angle-products]
                                        [--m-angle-products]
                                        [--m-rad-products] [--i-rad-products]

4.1.1.1. Frontend Initialization

swath extraction initialization options

--list-products

List available frontend products and exit

Default: False

--no-tc

Don’t use terrain-corrected navigation

Default: True

--day-fraction

Fraction of day required to produce reflectance products

Default: 0.1

--night-fraction

Fraction of night required to produce products like fog

Default: 0.1

--sza-threshold

Angle threshold of solar zenith angle used when deciding day or night

Default: 100.0

--dnb-saturation-correction

Enable dynamic DNB saturation correction (normally used for aurora scenes)

Default: False

4.1.1.2. Frontend Swath Extraction

swath extraction options

-p, --products

Specify frontend products to process

--adaptive-bt

Create adaptively scaled brightness temperature bands

--i-bands

Add all I-band raw products to list of products

--m-bands

Add all M-band raw products to list of products

--dnb-angle-products

Add DNB-band geolocation ‘angle’ products to list of products

--i-angle-products

Add I-band geolocation ‘angle’ products to list of products

--m-angle-products

Add M-band geolocation ‘angle’ products to list of products

--m-rad-products

Add M-band geolocation radiance products to list of products

--i-rad-products

Add I-band geolocation radiance products to list of products

Changed in version 2.1: The reader name has been changed to viirs_sdr although viirs is still supported for the time being.

Examples:

polar2grid.sh viirs_sdr gtiff -f <path to files>/<list of files>

viirs2awips.sh -g 211e 211w -f ../sdr/*.h5

polar2grid.sh viirs_sdr gtiff -h

polar2grid.sh viirs_sdr gtiff --list-products -f ../sdr/*.h5

polar2grid.sh viirs_sdr scmi -p i04 adaptive_dnb dynamic_dnb --sza-threshold=90.0 --letters --compress --sector-id Polar -g polar_alaska_1km -f <path to files>

polar2grid.sh viirs_sdr hdf5 --compress gzip --m-bands -f ../sdr/*.h5

polar2grid.sh viirs_sdr binary -g lcc_fit -p m15 -f ../sdr/SVM15*.h5 ../sdr/GMTCO*.h5