The Aqua 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 Aqua MODIS L1B product consists of three datasets (MYD02QKM, MYD02HKM, and MYD021KM) with three spatial-resolution variations: 250 meters, 500 meters, and 1000 meters.

This document describes the version 7.0 (v7.0) of the Aqua MODIS 500-m Calibrated Radiances product whose short-name is MYD02HKM. 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 500-m swath granule or data-file temporally spans 5 minutes, and its image dimensions measure 4,060 lines (along-track direction) by 2,708 samples (cross-track direction). The v7.0 collection’s data record starts from February 24, 2000 (2000–055).

The MYD02HKM product provides 500-m calibrated radiances for the following 5 bands:

Each 500-m band has 20 detectors in the along-track direction. The MYD02HKM product contains the following five Science Data Sets (SDS) besides geolocation fields for latitude and longitude, quality flags, error estimates, etc.

As evident from the above table, the 250-m (red and near-infrared) bands are also aggregated to 500 m through simple weighting functions that are applied to the data at their native resolution. 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, which 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.