MYD21C1 v061

MODIS/Aqua Land Surface Temperature/3-Band Emissivity Daily L3 Global 0.05 Deg CMG


PI: Glynn C. Hulley

Description

A new suite of MODIS Land Surface Temperature and Emissivity (LST&E) products are available in Collection 6.1. The MYD21 LST algorithm differs from the algorithm of the MYD11 LST products, in that the MYD21 algorithm is based on the ASTER Temperature/Emissivity Separation (TES) technique, whereas the MYD11 uses the split-window technique. The MYD21 TES algorithm uses a physics-based algorithm to retrieve dynamically both the LST and spectral emissivity simultaneously from the three MODIS thermal infrared bands 29, 31, and 32. The TES algorithm is combined with an improved Water Vapor Scaling (WVS) atmospheric correction scheme to stabilize the retrieval during very warm and humid conditions.

The MYD21C1 Version 6.1 dataset is produced daily from daytime Level 2 Gridded (L2G) intermediate LST products. The L2G process maps the daily MYD21 swath granules onto a sinusoidal MODIS grid and stores all observations falling over a gridded cell for a given day. The MOD21C1 algorithm sorts through all these observations for each cell and estimates the final LST value as an average from all observations that are cloud free and have good LST&E accuracies. The daytime average is weighted by the observation coverage for that cell. Only observations having observation coverage more than a certain threshold (15%) are considered for this averaging. The MYD21C1 product contains seven Science Datasets (SDS), which include the calculated LST as well as quality control, the three emissivity bands, view zenith angle, and time of observation. MYD21C1 products are available two months after acquisition due to latency of data inputs. Additional details regarding the methodology used to create this Level 3 (L3) product are available in the Algorithm Theoretical Basis Document (ATBD).

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Characteristics

Improvements/Changes from Previous Versions

  • The Version 6.1 Level-1B (L1B) products have been improved by undergoing various calibration changes that include: changes to the response-versus-scan angle (RVS) approach that affects reflectance bands for Aqua and Terra MODIS, corrections to adjust for the optical crosstalk in Terra MODIS infrared (IR) bands, and corrections to the Terra MODIS forward look-up table (LUT) update for the period 2012 - 2017.
  • A polarization correction has been applied to the L1B Reflective Solar Bands (RSB).
  • Three new CMG products are available in the MxD21 suite (MxD21C1/C2/C3).

Product Maturity

Validation at stage 1 has been achieved for the MODIS Land Surface Temperature and Emissivity data products. Further details regarding MODIS land product validation for the MYD21 data products are available from the MODIS Land Team Validation site.

Collection and Granule

Collection

Characteristic Description
CollectionAqua MODIS
DOI10.5067/MODIS/MYD21C1.061
File Size~65 MB
Temporal ResolutionDaily
Temporal Extent2002-07-04 to Present
Spatial ExtentGlobal
Coordinate SystemGeographic Latitude and Longitude
DatumN/A
File FormatHDF-EOS
Geographic DimensionsGlobal

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers25
Columns/Rows7200 x 3600
Pixel Size5600 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor Additional Offset
Count_Day Count of Daytime Input Values N/A 16-bit unsigned integer 0 N/A 1 to 65535 N/A N/A
Count_Night Count of Nighttime Input Values N/A 16-bit unsigned integer 0 N/A 1 to 65535 N/A N/A
QC_Day Quality Control for Daytime LST and Emissivity N/A 8-bit unsigned integer N/A N/A 0 to 255 N/A N/A
QC_Night Quality Control for Nighttime LST and Emissivity N/A 8-bit unsigned integer N/A N/A 0 to 255 N/A N/A
LST_Day Average Daytime Land Surface Temperature Kelvin 16-bit unsigned integer 0 N/A 7500 to 65535 0.02 N/A
LST_Night Average Nighttime Land Surface Temperature Kelvin 16-bit unsigned integer 0 N/A 7500 to 65535 0.02 N/A
LST_Day_err Root-mean-square-error Daytime Land Surface Temperature Kelvin 8-bit unsigned integer 0 N/A 1 to 255 0.04 N/A
LST_Night_err Root-mean-square-error Nighttime Land Surface Temperature Kelvin 8-bit unsigned integer 0 N/A 1 to 255 0.04 N/A
Day_view_angle Average Daytime View Zenith Angle Degree 8-bit unsigned integer 255 N/A 0 to 130 N/A -65
Night_view_angle Average Nighttime View Zenith Angle Degree 8-bit unsigned integer 255 N/A 0 to 130 N/A -65
Day_view_time Average Daytime View Time (UTC) Hours 8-bit unsigned integer 255 N/A 0 to 120 0.2 N/A
Night_view_time Average Nighttime View Time (UTC) Hours 8-bit unsigned integer 255 N/A 0 to 120 0.2 N/A
Emis_29_Day Average Daytime Band 29 Emissivity N/A 8-bit unsigned integer 0 N/A 1 to 255 0.002 0.49
Emis_29_Night Average Nighttime Band 29 Emissivity N/A 8-bit unsigned integer 0 N/A 1 to 255 0.002 0.49
Emis_29_Day_err Root-mean-square-error Daytime Band 29 Emissivity N/A 16-bit unsigned integer 0 N/A 1 to 65535 0.0001 N/A
Emis_29_Night_err Root-mean-square-error Nighttime Band 29 Emissivity N/A 16-bit unsigned integer 0 N/A 1 to 65535 0.0001 N/A
Emis_31_Day Average Daytime Band 31 Emissivity N/A 8-bit unsigned integer 0 N/A 1 to 255 0.002 0.49
Emis_31_Night Average Nighttime Band 31 Emissivity N/A 8-bit unsigned integer 0 N/A 1 to 255 0.002 0.49
Emis_31_Day_err Root-mean-square-error Daytime Band 31 Emissivity N/A 16-bit unsigned integer 0 N/A 1 to 65535 0.0001 N/A
Emis_31_Night_err Root-mean-square-error Nighttime Band 31 Emissivity N/A 16-bit unsigned integer 0 N/A 1 to 65535 0.0001 N/A
Emis_32_Day Average Daytime Band 32 Emissivity N/A 8-bit unsigned integer 0 N/A 1 to 255 0.002 0.49
Emis_32_Night Average Nighttime Band 32 Emissivity N/A 8-bit unsigned integer 0 N/A 1 to 255 0.002 0.49
Emis_32_Day_err Root-mean-square-error Daytime Band 32 Emissivity N/A 16-bit unsigned integer 0 N/A 1 to 65535 0.0001 N/A
Emis_32_Night_err Root-mean-square-error Nighttime Band 32 Emissivity N/A 16-bit unsigned integer 0 N/A 1 to 65535 0.0001 N/A
Percent_land_in_grid Percent of Land Detections in Grid Cell Percent 8-bit unsigned integer 255 N/A 1 to 100 N/A N/A

Product Quality

The Quality Control (QC) layer is stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret the quality layer.

The final quality bit for the output product reflects the lowest quality values from all observations that went into the final average. The bit definition index for the QC layer is available in Table 12 of the User Guide.

Known Issues

For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website.

Documentation

Using the Data

Access Data

Citation

DOI: 10.5067/MODIS/MYD21C1.061

About the Image

A global image of the Aqua MODIS land surface temperature (LST) data product from MYD21C1 August 15, 2020.

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