4.12. VIRR L1B Reader

The VIRR Level 1B reader operates on Level 1B (L1B) HDF5 files. Files usually have the following naming scheme:

tf2018343030324.FY3C-L_VIRRX_L1B.HDF or tf2018343092538.FY3B-L_VIRRX_L1B.HDF the numbers at the start are year julian-day hour minute seconds

This reader’s default resampling algorithm is ewa for Elliptical Weighted Averaging resampling. The --fornav-D parameter is set to 40 and the --fornav-d parameter is set to 1.

Product Name	Description	Central Wavelength (um)
1	Channel 1 Reflectance Band	0.63
2	Channel 2 Reflectance Band	0.865
3	Channel 3 Emissive Band	3.74
4	Channel 4 Emissive Band	10.8
5	Channel 5 Emissive Band	12.0
6	Channel 6 Reflectance Band	1.60
7	Channel 7 Reflectance Band	0.455
8	Channel 8 Reflectance Band	0.505
9	Channel 9 Reflectance Band	0.555
10	Channel 10 Reflectance Band	1.36
true_color	Ratio sharpened rayleigh corrected true color	N/A

4.12.1. Command Line Arguments

usage: polar2grid.sh virr_l1b <writer> [-h] [--list-products]
                                       [--day-fraction DAY_FRACTION]
                                       [--sza-threshold SZA_THRESHOLD]
                                       [-p PRODUCTS [PRODUCTS ...]]

4.12.1.1. Frontend Initialization

swath extraction initialization options

--list-products

List available frontend products and exit

Default: False

--day-fraction

Fraction of day required to produce reflectance products

Default: 0.1

--sza-threshold

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

Default: 100.0

4.12.1.2. Frontend Swath Extraction

swath extraction options

-p, --products

Specify frontend products to process

Examples:

$POLAR2GRID_HOME/bin/polar2grid.sh virr_l1b gtiff -h

polar2grid.sh virr_l1b hdf5 --list-products -f tf2019230221957.FY3B-L_VIRRX_L1B.HDF

polar2grid.sh virr_l1b gtiff -f ../l1b/*.HDF

polar2grid.sh virr_l1b gtiff -p 1 10 2 3 4 -f /viir/data/*FY3B-L_VIRRX_L1B.HDF

polar2grid.sh virr_l1b scmi -g lcc_conus_750 --sector-id LCC --compress --letters -p -p 1 2 3 4 5 -f /viir/data/tf*.HDF

polar2grid.sh virr_l1b binary -p 1 5 10 9 -g lcc_fit -f ../l1b/tf2019230221957.FY3B-L_VIRRX_L1B.HDF

polar2grid.sh virr_l1b gtiff --sza-threshold 50 -f tf2019286095509.FY3B-L_VIRRX_L1B.HDF