MOD03 - Geolocation - 1km
The Terra MODIS (Moderate resolution Imaging Spectroradiometer) Level-1A (L1A) Geolocation product contains geodetic coordinates, ground elevation, and solar and satellite zenith and azimuth angles for the center of each MODIS 1-km pixel at nadir. These data serve as a companion dataset to the Level-1B calibrated radiances (MOD02) and the higher-level products to enable further processing. These geolocation fields are determined using data inputs from the spacecraft attitude and orbit, instrument telemetry, and a digital elevation model.
This document describes the version 7.0 (v7.0) of the Terra MODIS 1-km Geolocation product whose short-name is MOD03. It represents the most current version of this product that has undergone around half-a-dozen reprocessing cycles in the last 2.5 decades. Each 1-km swath granule or data-file temporally spans 5 minutes, and its nominal image dimensions measure 2,030 lines (along-track direction) by 1,354 samples (cross-track direction). The v7.0 collection’s data record starts from February 24, 2000 (2000–055).
The following Science Data Sets (SDS) describe the range of information provided for each 1-km pixel’s Instantaneous Field of View (IFOV). A range of other information attributes (quality, offsets, observation start-time, etc.) exist as well.
| SDS Variable | Long-name |
|---|---|
| Geolocation Fields | |
| Latitude | Latitude |
| Latitude_500m | Latitude (500m) |
| Longitude | Longitude |
| Longitude_500m | Longitude (500m) |
| Data Fields | |
| gflags | gflags |
| Height | Height |
| Height_Offset | Height Offset |
| Height_500m | Height (500m) |
| Land-Sea Mask | Land-Sea Mask |
| Range | Range |
| Scan Offset | Scan Offset |
| Sensor Azimuth | Sensor Azimuth |
| Sensor Zenith | Sensor Zenith |
| Solar Azimuth | Solar Azimuth |
| Solar Zenith | Solar Zenith |
| Track Offset | Track Offset |
| Water Present | Water Present |
Geolocation-specific Changes in the v7.0 Collection
The L1A geolocation algorithm changes and improvements in the v7.0 collection relative to the previous v6.1 collection include the following:
- Added a new solar-eclipse flag.
- Added 500-m information for the geodetic latitude, longitude, and height variables.
- Revised the practice to use a yearly updated Land-Water Mask database over a static one.
- Refreshed the Ground Control Point (GCP) chip library as follows:
- Expanded the number of chips from 1214 to 2514.
- Extended the use of chips from 24 x 24 km to 42 x 42 km.
- Extended the error measurements from a scan angle of ±45 degrees to ±55 degrees.
- Extended error searches from an area of ±0.8 to ±2.5 250-m pixels.
- Increased the cross-correlation coefficient threshold from 0.6 to 0.85.
| Shortname: | MOD03 | ||||||||||||
| Platform: | Terra | ||||||||||||
| Instrument: | MODIS | ||||||||||||
| Processing Level: | Level-1A | ||||||||||||
| Data Format: | netCDF4 | ||||||||||||
| Temporal Resolution: | 5 minute | ||||||||||||
| ArchiveSet(s): | 7 | ||||||||||||
| Collection: | MODIS Collection 7, Level 1, Atmosphere, Land (ArchiveSet 7) | ||||||||||||
| PGE Number: | PGE01 | ||||||||||||
| File Naming Convention: |
Syntax: ESDT.AYYYYDDD.HHMM.CCC.YYYYDDDHHMMSS.Format Example: MOD03.A2025031.0850.007.2025177004048.nc
|
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| Keywords: | Terra, MODIS, L1A, 1 km, Geolocation |
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