4.3. MODIS L1B Reader

The MODIS Reader operates on HDF4 Level 1B files from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Aqua and Terra satellites. The reader is designed to work with files created by the IMAPP direct broadcast processing system (file naming conventions such as a1.17006.1855.1000m.hdf), but can support other types of L1B files, including the NASA archived files (file naming conventions such as MOD021KM.A2017004.1732.005.2017023210017.hdf). The reader can be specified to the polar2grid.sh script by using the reader name modis.

This reader’s default resampling algorithm is ewa for Elliptical Weighted Averaging resampling. The --fornav-D parameter is set to 10 and the --fornav-d parameter is set to 1.

It provides the following products:

Product Name

Description

vis01

Visible 1 Band

vis02

Visible 2 Band

vis03

Visible 3 Band

vis04

Visible 4 Band

vis05

Visible 5 Band

vis06

Visible 6 Band

vis07

Visible 7 Band

vis26

Visible 26 Band

bt20

Brightness Temperature Band 20

bt21

Brightness Temperature Band 21

bt22

Brightness Temperature Band 22

bt23

Brightness Temperature Band 23

bt24

Brightness Temperature Band 24

bt25

Brightness Temperature Band 25

bt27

Brightness Temperature Band 27

bt28

Brightness Temperature Band 28

bt29

Brightness Temperature Band 29

bt30

Brightness Temperature Band 30

bt31

Brightness Temperature Band 31

bt32

Brightness Temperature Band 32

bt33

Brightness Temperature Band 33

bt34

Brightness Temperature Band 34

bt35

Brightness Temperature Band 35

bt36

Brightness Temperature Band 36

ir20

Radiance Band 20

ir21

Radiance Band 21

ir22

Radiance Band 22

ir23

Radiance Band 23

ir24

Radiance Band 24

ir25

Radiance Band 25

ir27

Radiance Band 27

ir28

Radiance Band 28

ir29

Radiance Band 29

ir30

Radiance Band 30

ir31

Radiance Band 31

ir32

Radiance Band 32

ir33

Radiance Band 33

ir34

Radiance Band 34

ir35

Radiance Band 35

ir36

Radiance Band 36

cloud_mask

Cloud Mask

land_sea_mask

Land Sea Mask

snow_ice_mask

Snow Ice Mask

sst

Sea Surface Temperature

lst

Land Surface Temperature

slst

Summer Land Surface Temperature

ndvi

Normalized Difference Vegetation Index

ist

Ice Surface Temperature

inversion_strength

Inversion Strength

inversion_depth

Inversion Depth

ice_concentration

Ice Concentration

ctt

Cloud Top Temperature

tpw

Total Precipitable Water

fog

Temperature Difference between BT31 and BT20

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 90 degrees.

4.3.1. Command Line Arguments

usage: polar2grid.sh modis <writer> [-h] [--list-products]
                                    [-p PRODUCTS [PRODUCTS ...]]
                                    [--ir-products] [--bt-products]
                                    [--vis-products] [--edr-products]
                                    [--mask-products] [--adaptive-bt]

4.3.1.1. Frontend Initialization

swath extraction initialization options

--list-products

List available frontend products and exit

Default: False

4.3.1.2. Frontend Swath Extraction

swath extraction options

-p, --products

Specify frontend products to process

--ir-products

Add IR products to list of products

--bt-products

Add BT products to list of products

--vis-products

Add Visible products to list of products

--edr-products

Add EDR products and temperature difference ‘fog’ to list of products

--mask-products

Add cloud and other mask products to list of products

--adaptive-bt

Create adaptively scaled brightness temperature bands

Examples:

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

polar2grid.sh modis gtiff -h

polar2grid.sh modis gtiff --list-products -f /data

polar2grid.sh modis gtiff -p vis01 -f ../l1b/a1.17006.1855.250m.hdf ../l1b/a1.17006.1855.geo.hdf

polar2grid.sh modis gtiff --grid-configs ${POLAR2GRID_HOME}/grid_configs/grid_example.conf -g my_latlon -f ../l1b/a1.17006.1855.250m.hdf ../l1b/a1.17006.1855.geo.hdf

polar2grid.sh modis scmi --sector-id LCC -g lcc_conus_1km --letters --compress --bt-products --grid-coverage=.05 -f MOD021KM.A2017004.1732*.hdf MOD03.A2017004.1732*.hdf

polar2grid.sh modis awips -g 203 204 210 -p vis01 vis06 vis26 bt20 bt31 bt35 bt27 -f /data/modis/MOD021KM.A2017004.1732.005.2017023210017.hdf /data/modis/MOD03.A2017004.1732.005.2017023210017.hdf

polar2grid.sh modis hdf5 --bt-products --add-geolocation --grid-coverage=.05 -f /data/MOD*.hdf

polar2grid.sh modis hdf5 -g wgs84_fit_250 -f /data/rad/MOD02QKM.*.hdf /data/geo/MOD03.*.hdf

polar2grid.sh modis binary -f /aqua/a1.17006.1855.500m.hdf /aqua/a1.17006.1855.geo.hdf