4.13. MERSI-2 L1B Reader

The MERSI2 Level 1B reader operates on Level 1B (L1B) HDF5 files. The files come in four varieties; band data and geolocation data, both at 250m and 1000m resolution. Files usually have the following naming scheme:

tf{start_time:%Y%j%H%M%S}.{platform_shortname}-{trans_band:1s}_MERSI_1000M_L1B.{ext}

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	0.47
2	Channel 2 Reflectance Band	0.55
3	Channel 3 Reflectance Band	0.65
4	Channel 4 Reflectance Band	0.865
5	Channel 5 Reflectance Band	1.38
6	Channel 6 Reflectance Band	1.64
7	Channel 7 Reflectance Band	2.13
8	Channel 8 Reflectance Band	0.412
9	Channel 9 Reflectance Band	0.443
10	Channel 10 Reflectance Band	0.490
11	Channel 11 Reflectance Band	0.555
12	Channel 12 Reflectance Band	0.670
13	Channel 13 Reflectance Band	0.709
14	Channel 14 Reflectance Band	0.746
15	Channel 15 Reflectance Band	0.865
16	Channel 16 Reflectance Band	0.905
17	Channel 17 Reflectance Band	0.936
18	Channel 18 Reflectance Band	0.940
19	Channel 19 Reflectance Band	1.24
20	Channel 20 Brightness Temperature Band	3.80
21	Channel 21 Brightness Temperature Band	4.05
22	Channel 22 Brightness Temperature Band	7.20
23	Channel 23 Brightness Temperature Band	8.55
24	Channel 24 Brightness Temperature Band	10.8
25	Channel 25 Brightness Temperature Band	12.0
true_color	Rayleigh corrected true color RGB	N/A
false_color	False color RGB (bands 7, 4, 3)	N/A
natural_color	Natural color RGB (bands 6, 4, 3)	N/A

4.13.1. Command Line Arguments

usage: polar2grid.sh mersi2_l1b <writer> [-h] [--list-products]
                                         [--day-fraction DAY_FRACTION]
                                         [--sza-threshold SZA_THRESHOLD]
                                         [-p PRODUCTS [PRODUCTS ...]]

4.13.1.1. 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

4.13.1.2. Frontend Swath Extraction

swath extraction options

-p, --products

Specify frontend products to process

Examples:

$POLAR2GRID_HOME/bin/polar2grid.sh mersi2_l1b gtiff -h

polar2grid.sh mersi2_l1b gtiff --list-products -f tf2019259173245.FY3D-X_MERSI*.HDF

polar2grid.sh mersi2_l1b gtiff -p 1 2 3 4 6 7 20 25 -f tf2019233172521.FY3D-X_MERSI_0250M_L1B.HDF tf2019233172521.FY3D-X_MERSI_1000M_L1B.HDF tf2019233172521.FY3D-X_MERSI_GEOQK_L1B.HDF tf2019233172521.FY3D-X_MERSI_GEO1K_L1B.HDF

polar2grid.sh mersi2_l1b gtiff -p true_color false_color -g lcc_fit -f ../mersi/tf2019259173245.FY3D-X_MERSI*.HDF

polar2grid.sh mersi2_l1b hdf5 -p 20 21 22 23 24 25  --grid-configs ${HOME}/my_grid.conf -g shanghai seoul -f ../data/*.HDF

polar2grid.sh mersi2_l1b binary --sza-threshold=90  -p 1 2 3 4 6 7 20 25 -f tf2019226095418.FY3D-X_MERSI_*.HDF