MOD021KM - Level 1B Calibrated Radiances - 1km
The Terra MODIS (Moderate resolution Imaging Spectroradiometer) Level-1B (L1B) product includes calibrated and geolocated at-aperture radiances for 36 bands generated from MODIS Level-1A raw sensor counts. The radiances are provided in watts/m2/micrometer (µm)/steradian. The Terra MODIS L1B product is a set of three datasets (MOD02QKM, MOD02HKM, and MOD021KM) that are produced to address the three spatial-resolution variations: 250 m, 500 m, and 1000 m.
This document describes the version 7.0 (v7.0) of the Terra MODIS 1000-m Calibrated Radiances product whose short-name is MOD021KM. 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 1000-m swath granule or data-file temporally spans 5 minutes, and its 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 MOD021KM product provides 1000-m calibrated radiances for the following 29 bands:
| Band | Wavelength |
|---|---|
| Band 8 (VNIR)* | 0.405 µm – 0.420 µm |
| Band 9 (VNIR) | 0.438 µm – 0.448 µm |
| Band 10 (VNIR) | 0.483 µm – 0.493 µm |
| Band 11 (VNIR) | 0.526 µm – 0.536 µm |
| Band 12 (VNIR) | 0.546 µm – 0.556 µm |
| Band 13 (VNIR) | 0.662 µm – 0.672 µm |
| Band 14 (VNIR) | 0.673 µm – 0.683 µm |
| Band 15 (VNIR) | 0.743 µm – 0.753 µm |
| Band 16 (VNIR) | 0.862 µm – 0.877 µm |
| Band 17 (VNIR) | 0.890 µm – 0.920 µm |
| Band 18 (VNIR) | 0.931 µm – 0.941 µm |
| Band 19 (VNIR) | 0.915 µm – 0.965 µm |
| Band 20 (SWIR & TIR)** | 3.660 µm – 3.840 µm |
| Band 21 (SWIR & TIR) | 3.929 µm – 3.989 µm |
| Band 22 (SWIR & TIR) | 3.929 µm – 3.989 µm |
| Band 23 (SWIR & TIR) | 4.020 µm – 4.080 µm |
| Band 24 (SWIR & TIR) | 4.433 µm – 4.498 µm |
| Band 25 (SWIR & TIR) | 4.482 µm – 4.549 µm |
| Band 26 (SWIR & TIR) | 1.360 µm – 1.390 µm |
| Band 27 (SWIR & TIR) | 6.535 µm – 6.895 µm |
| Band 28 (SWIR & TIR) | 7.175 µm – 7.475 µm |
| Band 29 (SWIR & TIR) | 8.400 µm – 8.700 µm |
| Band 30 (SWIR & TIR) | 9.580 µm – 9.880 µm |
| Band 31 (SWIR & TIR) | 10.780 µm – 11.280 µm |
| Band 32 (SWIR & TIR) | 11.770 µm – 12.270 µm |
| Band 33 (SWIR & TIR) | 13.185 µm – 13.485 µm |
| Band 34 (SWIR & TIR) | 13.485 µm – 13.785 µm |
| Band 35 (SWIR & TIR) | 13.785 µm – 14.085 µm |
| Band 36 (SWIR & TIR) | 14.085 µm – 14.385 µm |
* VNIR: Visible and Near-Infrared; **SWIR & TIR: Shortwave Infrared and Thermal Infrared
Each 1-km band has 10 detectors in the along-track direction. The MOD021KM product contains twelve Science Data Sets (SDS) besides geolocation fields for latitude and longitude, quality flags, error estimates, etc. (See table below)
| SDS Variable | Long-name |
|---|---|
| EV_1KM_Emissive | Earth View 1KM Emissive Bands Scaled Integers |
| EV_1KM_Emissive_Uncert_Indexes | Earth View 1KM Emissive Bands Uncertainty Indexes |
| EV_1KM_RefSB | Earth View 1KM Reflective Solar Bands Scaled Integers |
| EV_1KM_RefSB_Uncert_Indexes | Earth View 1KM Reflective Solar Bands Uncertainty Indexes |
| EV_250_Aggr1km_RefSB | Earth View 250M Aggregated 1km Reflective Solar Bands Scaled Integers |
| EV_250_Aggr1km_RefSB_Samples_Used | Earth View 250M Aggregated 1km Reflective Solar Bands Number of Samples Used in Aggregation |
| EV_250_Aggr1km_RefSB_Uncert_Indexes | Earth View 250M Aggregated 1km Reflective Solar Bands Uncertainty Indexes |
| EV_500_Aggr1km_RefSB | Earth View 500M Aggregated 1km Reflective Solar Bands Scaled Integers |
| EV_500_Aggr1km_RefSB_Samples_Used | Earth View 500M Aggregated 1km Reflective Solar Bands Number of Samples Used in Aggregation |
| EV_500_Aggr1km_RefSB_Uncert_Indexes | Earth View 500M Aggregated 1km Reflective Solar Bands Uncertainty Indexes |
| EV_Band26 | Earth View Band 26 Scaled Integers |
| EV_Band26_Uncert_Indexes | Earth View Band 26 Uncertainty Indexes |
In addition to the data and information for the 1-km reflective solar and thermal emissive bands, aggregated 250-m and 500-m bands are also generated through simple weighting functions that are applied to the data at their native resolution. Band 26 is a reflective solar band (RSB), which is handled uniquely. Notwithstanding its RSB status, it is transmitted along with the thermal band data. Consequently, the band order for the night-mode data is re-organized so that the Band 26 data are written to the RSB 1-km SDSs and not to the emissive band SDSs. Consult the MODIS L1B User Guide to understand how to convert the per-pixel scaled integers to radiance or reflectance.
Radiometric Calibration-specific Changes in the v7.0 Collection
The L1B calibration algorithms for the v7.0 collection include several updates compared to the previous v6.1 algorithms, that improve the radiometric accuracy and long-term stability of the L1B reflectance, radiance, and brightness temperature. The updated algorithms are applied consistently across the entire missions for v7.0. The most significant changes include the following:
Reflective Solar Bands (RSB) updates:
- A correction for changing instrument polarization sensitivity is applied to the desert-scene data before using that data to derive the response-versus-scan angle (RVS) for Terra MODIS bands 3, 4, 8, 9, and 10. Additional improvements are also made to the desert data-fitting algorithms for both Terra and Aqua MODIS.
- For the Terra MODIS Short-wave Infrared (SWIR) bands, data from deep convective clouds are used to apply drift corrections and derive an on-orbit RVS for bands 5 and 26. The optical and electronic crosstalk-correction algorithms for these bands were also improved.
- An inter-band calibration approach that relies on relative trends over ocean scenes is used to correct for drift in Terra bands 11 and 12.
Thermal Emissive Bands (TEB) updates:
- Electronic crosstalk correction is applied to the Aqua MODIS Photovoltaic (PV) Long-wave Infrared (LWIR) bands 27–30 over the entire mission. Crosstalk correction is also applied to select Mid-wave Infrared (MWIR) detectors in both Terra and Aqua MODIS. Adjustments were made to the L1B code to improve the handling of crosstalk correction at the image-edge frames.
- Data from deep convective clouds are used to apply bias corrections to Terra MODIS bands 20 and 29 and Aqua MODIS bands 27 through 30 as well as to improve the scan mirror-side differences in the Aqua MODIS TEBs.
- Adjustments are applied to the non-linear calibration coefficients for Terra and Aqua MODIS band 30 to improve long-term stability.
| Shortname: | MOD021KM | ||||||||||||||
| Platform: | Terra | ||||||||||||||
| Instrument: | MODIS | ||||||||||||||
| Processing Level: | Level-1B | ||||||||||||||
| Data Format: | netCDF4 | ||||||||||||||
| Temporal Resolution: | 5 minute | ||||||||||||||
| ArchiveSet(s): | 7 | ||||||||||||||
| Collection: | MODIS Collection 7, Level 1, Atmosphere, Land (ArchiveSet 7) | ||||||||||||||
| PGE Number: | PGE02 | ||||||||||||||
| File Naming Convention: |
Syntax: ESDT.AYYYYDDD.HHMM.CCC.YYYYDDDHHMMSS.Format Example: MOD021KM.A2025031.0850.007.2025177004642.nc
|
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| Keywords: | Terra, MODIS, L1B, 1000 m, Calibrated Radiances |
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