Earth Data School
About
Full catalog/VJ121A1N
VJ121A1N·v002·dataset

How hot the land surface gets, nighttime (NOAA-20, daily, 1 km)

VIIRS/JPSS1 Land Surface Temperature/Emissivity Daily L3 Global 1km SIN Grid Night V002
land NASA LPCLOUD Level 3 active HDF-EOS5
In plain English

What it measures. Daily nighttime land-surface temperature across the globe at 1 km resolution, basically how warm the ground itself is at night, along with how efficiently each surface radiates heat (emissivity).

How it's made. Compiled daily from nighttime VIIRS observations on the NOAA-20 satellite, averaging cloud-free readings within each grid cell; built to match NASA's MODIS temperature products.

How & where you'd use it. Helpful for studying urban heat, drought, agriculture, and energy balance, and for building consistent long-term temperature records.

What's measured

LAND SURFACE › SURFACE RADIATIVE PROPERTIES › EMISSIVITYLAND SURFACE › SURFACE THERMAL PROPERTIES › LAND SURFACE TEMPERATURE

Coverage & cadence

  • Time span2018-01-01 → ongoing
  • Measured byNOAA-20 (VIIRS)
  • Processing levelLevel 3
  • Spatial extent-180, -90, 180, 90
  • FormatsHDF-EOS5
  • StatusACTIVE

What you can do with it

  • Track deforestation, fire scars and land-cover change
  • Monitor crop and vegetation health (NDVI/EVI)
  • Map how built-up vs. green an area is over time
Official description

The NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Land Surface Temperature and Emissivity (LST&E) Night Version 2 product (VJ121A1N) is compiled daily from nighttime Level 2 Gridded (L2G) intermediate products. The L2G process maps the daily [VJ121](https://doi.org/10.5067/VIIRS/VJ121.002) swath granules onto a sinusoidal MODIS grid and stores all observations overlapping a gridded cell for a given night. The VJ121A1 algorithm sorts through all these observations for each cell and estimates the final LST value as an average from all cloud-free observations that have good LST accuracies. The nighttime 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 1 kilometer dataset is derived through resampling the native 750 meter VIIRS resolution in the input product. The VJ121A1N product is developed synergistically with the Moderate Resolution Imaging Spectroradiometer (MODIS) LST&E Version 6.1 product ([MOD21A1N](https://doi.org/10.5067/MODIS/MOD21A1N.061)) using the same input atmospheric products and algorithmic approach. 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. Additional details regarding the method used to create this Level 3 (L3) product are available in the Algorithm Theoretical Basis Document (ATBD). The VJ121A1N product contains seven Science Datasets (SDS) variables: LST, quality control, emissivity for bands M14, M15, and M16, view zenith angle, and time of observation. A low-resolution browse image for LST is also available for each VJ121A1N granule. Known Issues * For complete information about known issues please refer to the [MODIS/VIIRS Land Quality Assessment website](https://landweb.modaps.eosdis.nasa.gov/knownissue?sensor=VIIRS) and the User Guide.

Get the data

vj121a1n_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="VJ121A1N",
    version="002",
    bounding_box=(-122.5, 37.2, -121.8, 37.9),  # your area (W,S,E,N)
    temporal=("2024-01-01", "2024-12-31"),       # your dates
)
files = earthaccess.open(results)   # stream straight from LPCLOUD
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.