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).
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.
Characteristic | Description |
---|---|
Collection | Aqua MODIS |
DOI | 10.5067/MODIS/MYD21C1.061 |
File Size | ~65 MB |
Temporal Resolution | Daily |
Temporal Extent | 2002-07-04 to Present |
Spatial Extent | Global |
Coordinate System | Geographic Latitude and Longitude |
Datum | N/A |
File Format | HDF-EOS |
Geographic Dimensions | Global |
Characteristic | Description |
---|---|
Number of Science Dataset (SDS) Layers | 25 |
Columns/Rows | 7200 x 3600 |
Pixel Size | 5600 m |
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 |
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.
For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website.