VNP21 v001

VIIRS/NPP Land Surface Temperature and Emissivity 6-Min L2 Swath 750 m


PI: Glynn Hulley

Description

The NASA Suomi National Polar-Orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Land Surface Temperature and Emissivity (LST&E) Version 1 swath product (VNP21) is produced daily in 6-minute temporal increments of satellite acquisition. The VNP21 product uses a physics-based algorithm to dynamically retrieve both the LST and emissivity simultaneously for VIIRS thermal infrared bands M14 (8.55 µm), M15 (10.76 µm), and M16 (12 µm) at a spatial resolution of 750 meters.

The VNP21 product is developed synergistically with the Moderate Resolution Imaging Spectroradiometer (MODIS) LST&E Version 6 product (MOD21) using the same input atmospheric products and algorithmic approach based on the ASTER Temperature Emissivity Separation (TES) technique. 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 overall objective for NASA VIIRS products is to ensure the algorithms and products are compatible with the MODIS Terra and Aqua algorithms to promote the continuity of the Earth Observation System (EOS) mission. VIIRS LST&E products are available two months after acquisition due to latency of data inputs. Additional details regarding the method used to create this Level 2 (L2) product are available in the Algorithm Theoretical Basis Document (ATBD).

Provided in the VNP21 product are layers for LST, quality control, emissivity for bands M14, M15, and M16, LST&E errors, view angle, ASTER Global Emissivity Dataset (GED), Precipitable Water Vapor (PWV), ocean-land mask, latitude, and longitude. A low-resolution browse image for LST is also available for each VNP21 granule.

Characteristics

Collection and Granule

Collection

Characteristic Description
CollectionS-NPP VIIRS
DOI10.5067/VIIRS/VNP21.001
File Size~100 MB
Temporal Resolution< Daily
Temporal Extent2012-01-19 to Present
Spatial ExtentGlobal
Coordinate SystemNone (Swath)
DatumN/A
File FormatNetCDF4
Geographic Dimensions3060 km x 3060 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers15
Columns/Rows3200 x 3232
Pixel Size750 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor Additional Offset
LST Land Surface Temperature Kelvin 16-bit unsigned integer 0 N/A 7500 to 65535 0.02 N/A
QC Quality control for LST and emissivity N/A 16-bit unsigned integer 0 N/A 0 to 65535 N/A N/A
Emis_14 M14 emissivity N/A 8-bit unsigned integer 0 N/A 1 to 255 0.002 0.49
Emis_15 M15 emissivity N/A 8-bit unsigned integer 0 N/A 1 to 255 0.002 0.49
Emis_16 M16 emissivity N/A 8-bit unsigned integer 0 N/A 1 to 255 0.002 0.49
LST_err Land Surface Temperature error Kelvin 8-bit unsigned integer 0 N/A 1 to 255 0.04 N/A
Emis_14_err M14 emissivity error N/A 16-bit unsigned integer 0 N/A 0 to 65535 0.0001 N/A
Emis_15_err M15 emissivity error N/A 16-bit unsigned integer 0 N/A 0 to 65535 0.0001 N/A
Emis_16_err M16 emissivity error N/A 16-bit unsigned integer 0 N/A 0 to 65535 0.0001 N/A
View_angle VIIRS view angle for current pixel Degree 8-bit unsigned integer 255 N/A 0 to 180 0.5 N/A
Emis_ASTER ASTER GED Emissivity (minimum of 5 band values) N/A 8-bit unsigned integer 0 N/A 1 to 255 0.002 0.49
PWV Precipitable Water Vapor cm 16-bit unsigned integer 0 N/A 0 to 65535 0.001 N/A
oceanpix Ocean-land mask N/A 8-bit unsigned integer N/A N/A 0 to 2 N/A N/A
latitude Pixel Latitude Degree 32-bit floating point -999 N/A -90 to 90 N/A N/A
longitude Pixel Longitude Degree 32-bit floating point -999 N/A -180 to 180 N/A N/A

Ocean-land mask Values

Value Description
0 Land
1 Water
2 Inland water

Product Quality

The bit flags for the QC layer are defined in Table 5 on page 19 of the User Guide.

For additional information on product quality, refer to the VIIRS Land Product Quality website.

Known Issues

No known issues.

Documentation

Using the Data

Tools

Citation

DOI: 10.5067/VIIRS/VNP21.001

About the Image

LST from the VNP21 product over Chad, Africa during March 30, 2018 .