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