l1aextract_modis |

### l1aextract_modis

Creates an extracted L1A MODIS file.

Location
Details
Command Line Usage

#### Location

SeaDAS-Toolbox -> SeaDAS Processors -> extractor

#### Details

l1aextract_modis extracts a MODIS Level 1A sub-scene from an input Aqua or Terra L1A and GEO file. Users can specify a sub-scene either using longitude/latitude of southwest and northeast corners (swlon, swlat, nelon, nelat) or using start/end pixel numbers in conjunction with start/end lines. The former is referred to as lon/lat arguments and the latter is referred as pixel arguments. Once a user choose to specify the sub-scene using the lon/lat option, all four arguments must be specified. The program will fail to extract if any argument is missing.

Alternatively, users can directly specify pixel arguments to extract a sub-scene.

l1aextract_modis GUI

Arguments/Keywords

UI Element Name | Type | Description | Required/Optional | Default Value
infile | Text Field | Input MODIS Aqua or Terra L1A file to be extracted, or an L1A filelist for multiple file extraction. (Required) | Required |
ofile | Text Field | Output filename for the L1A extracted subscene. A default ofile name is generated by the program. | Required |
swlon | Text Field | Longitude of southwest corner of the box to be extracted. | Conditional |
swlat | Text Field | Latitude of southwest corner of the box to be extracted. | Conditional |
nelon | Text Field | Longitude of northeast corner of the box to be extracted. | Conditional |
nelat | Text Field | Latitude of northeast corner of the box to be extracted. | Conditional |
spixl | int | Starting pixel in infile for extracting. | Conditional |
epixl | int | Ending pixel in infile for extracting. | Conditional |
sline | int | Starting line in infile for extracting. | Conditional |
eline | int | Ending line in infile for extracting. | Conditional |

Actions/Buttons

UI Element Name | Type | Description
Browser Button | Button | Selects infile/ofile
Compute PixLines from LonLat | Button | Derives spixl, epixl, sline, and eline arguments from swlon, swlat, nelon, and nelat arguments by internally executing the lonlat2pixline program.
Load Parameters ... | Button | Reads in previously saved parameters and populates the fields in GUI.
Store Parameters ... | Button | Saves the current arguments in GUI in a file.
Run | Button | Executes the l1aextract_modis command with arguments provided in the UI.
Cancel | Button | Closes current processor GUI.
Apply | Button | Makes current arguments effective.
Open in SeaDAS | Checkbox | If selected, the ofile will be added to the open products list right after its generation.
? | Button | Displays the help content of the current command.

#### Command Line Usage

    This is version 0.76 of l1aextract_modis (compiled on Aug 21 2025 23:36:51)

    Usage: l1aextract_modis infile spixl epixl sline eline outfile
       where:
    	infile   - input MODIS L1A datafile
    	spixl    - start pixel number (1-based)
    	epixl    - end pixel number (1-based)
    	sline    - start line (1-based)
    	eline    - end line (1-based)
    	outfile  - output file name

    Note: Enter line number NOT scan number!