VIIRS LST (VNP21)¶

VIIRS Land Surface Temperature and Emissivity VNP21 (Suomi NPP), VJ121 (NOAA-20) and VJ221 (NOAA-21) Version 2 (VIIRS TES 1 km day and night land surface temperature and 3-band emissivity)

Available

At a glance¶

Note on period: Suomi NPP (VNP21) from 2012-01-17 (delivery scheduled to end on 2026-11-02), NOAA-20 (VJ121) from 2018-01-01, NOAA-21 (VJ221) from 2023-02-10 (monthly CMG from the 2023-02 period). VJ221 LST was released on 14 April 2026. The V2 collection was released on 29 June 2023, and distribution of the earlier V1 ended on 8 April 2025.

Overview¶

NASA's VIIRS land surface temperature product, which retrieves clear-sky land surface (skin) temperature together with emissivity from the VIIRS thermal infrared bands M14, M15 and M16. It uses the same temperature/emissivity separation (TES) algorithm, atmospheric inputs and water vapour scaling as MODIS MOD21 so as to continue the MODIS record, and the developers report agreement between the two sensors' LST within about ±0.5 K. There are Suomi NPP (VNP21), NOAA-20 (VJ121) and NOAA-21 (VJ221) versions, all on afternoon orbits crossing around 13:30, so they mainly take over from MODIS Aqua. Products come as daily and 8-day 1 km tiles and as daily, 8-day and monthly 0.05° global grids.

What changes with the successor¶

VIIRS LST V1 (VNP21 Collection 1) → VIIRS LST V2¶

Transition: 2023-06

Calibration coefficients and geolocation were improved for the whole Suomi NPP mission, and NOAA-20 (VJ121), NOAA-21 (VJ221) and 0.05° CMG products were added. The atmospheric input changed from MERRA-2 to GEOS-5, and inland water bodies are now retrieved. Distribution of V1 ended on 8 April 2025.

Sources: VNP21A1D V002 collection description (version description) · VIIRS Version 1 SR, VI, LAI/FPAR, LST, Active Fires Data Products Decommissioned (2025-04-08)

Available variables¶

Variables from the LP DAAC data catalog and the VNP21 Collection 2 User's Guide. Files are HDF-EOS5 (HDF5); physical value = stored value × scale_factor (+ offset). LST uses scale 0.02 (K) and stored value 0 is fill. VJ121 and VJ221 files use the same names. As with MOD21, contaminated pixels are not removed, so you must screen them with QC yourself.

instantaneous mean accumulated maximum minimum static — instantaneous: value at the time stamp · mean/accumulated/maximum/minimum: over the indicated interval · static: does not change with time

Daily 1 km (VNP21A1D day / VNP21A1N night; same for VJ121 and VJ221)¶

8-day 1 km (VNP21A2, VJ121A2, VJ221A2)¶

0.05° global grid (VNP21C1 daily / C2 8-day / C3 monthly)¶

Static information¶

The full variable list is in the official documentation.

How to get the data¶

• NASA Earthdata Search (LP DAAC, Earthdata Cloud) — HTTPS download / earthaccess / Earthdata Search
  • Example short names: VNP21A1D, VNP21A1N, VNP21A2, VNP21C1, VNP21C2, VNP21C3, VNP21 (L2); replace VNP with VJ1 for NOAA-20 and VJ2 for NOAA-21. All are version 002. Files are served over HTTPS from data.lpdaac.earthdatacloud.nasa.gov and need a free Earthdata Login.
• AppEEARS (area and point subsetting) — Web / API — point time series and area extracts as GeoTIFF or NetCDF4
  • Lets you request only the area, period and layers you need and reproject to geographic coordinates.
• Direct access in AWS us-west-2 (S3) — Cloud storage (S3, from within us-west-2 only)
  • Stored in Earthdata Cloud and readable directly from within us-west-2 with temporary credentials.

Example code¶

Downloads NOAA-20 VJ121A1D (daytime) daily files with earthaccess and opens them with h5py, locating variables by name rather than hard-coding the HDF-EOS5 path. Keeps only pixels whose mandatory QA (bits 0–1) is 00 (best) or 01 (nominal).

# pip install earthaccess h5py numpy
import earthaccess
import h5py
import numpy as np

earthaccess.login()  # free NASA Earthdata account
results = earthaccess.search_data(
    short_name="VJ121A1D", version="002",
    temporal=("2024-08-01", "2024-08-03"),
    bounding_box=(126.5, 37.0, 127.5, 38.0),   # (west, south, east, north) around Seoul
)
files = earthaccess.download(results, "vj121")

def find(h5, name):
    hits = []
    h5.visititems(lambda path, obj: hits.append(path) if path.endswith("/" + name) else None)
    return h5[hits[0]][()]

with h5py.File(files[0], "r") as f:
    lst = find(f, "LST_1KM").astype("float64")
    qc = find(f, "QC")

good = (lst > 0) & ((qc & 0b11) <= 1)          # drop fill + keep mandatory QA 00 or 01
lst_k = np.where(good, lst * 0.02, np.nan)      # K
print(np.nanmean(lst_k) - 273.15)

Practical tips¶

• Suomi NPP data delivery ends at 15:40 UTC on 2 November 2026 (NOAA notice; the Earthdata notice title says 1 November). Start new analyses with NOAA-21 (VJ221) or NOAA-20 (VJ121).
• VIIRS LST uses the same method as MOD21 (TES), so it continues MOD21 well, but it differs in algorithm from MOD11 (split-window) and can differ by several K over arid land.
• Like MOD21, contaminated pixels are not set to fill. Dust and undetected cloud over deserts can produce hot outliers, so screen with the QC bits, emissivity and error estimates together.
• Low emissivity does not always mean cloud. The User's Guide notes that real surfaces such as mafic rocks can have M15/M16 emissivity below 0.9.
• Mandatory QA bits 01 (nominal) mean 'usable with caution'. The 'poor' boundary of the LST accuracy bits differs by product: 2.5 K for L2 and 2 K for A1 and A2.
• The 1 km tiles are resampled from 750 m data. If you need the native 750 m resolution, use the L2 swath products (VNP21, VJ121, VJ221).
• The three satellites' overpass times differ slightly, which can produce differences of around 0.5 K in summer. When combining satellites, process each one separately and then compare.
• LST is surface (skin) temperature, not 2 m air temperature. It is much higher than air temperature at midday and lower on clear nights.
• Files are HDF-EOS5 (HDF5). pyhdf code written for MODIS (HDF4) will not work; read them with h5py or xarray (h5netcdf).

Notices and change history¶

References for your paper¶

Dataset citation¶

VNP21A1D V002 (Suomi NPP daytime daily) — DOI 10.5067/VIIRS/VNP21A1D.002

@misc{vnp21a1d_v002,
  author    = {Hulley, Glynn and Hook, Simon},
  title     = {{VIIRS/NPP} Land Surface Temperature/Emissivity Daily {L3} Global 1km {SIN} Grid Day {V002}},
  year      = {2023},
  publisher = {NASA Land Processes Distributed Active Archive Center},
  doi       = {10.5067/VIIRS/VNP21A1D.002}
}

VNP21A2 V002 (Suomi NPP 8-day) — DOI 10.5067/VIIRS/VNP21A2.002

@misc{vnp21a2_v002,
  author    = {Hulley, Glynn and Hook, Simon},
  title     = {{VIIRS/NPP} Land Surface Temperature/Emissivity 8-Day {L3} Global 1km {SIN} Grid {V002}},
  year      = {2023},
  publisher = {NASA Land Processes Distributed Active Archive Center},
  doi       = {10.5067/VIIRS/VNP21A2.002}
}

VJ121A1D V002 (NOAA-20 daytime daily) — DOI 10.5067/VIIRS/VJ121A1D.002

@misc{vj121a1d_v002,
  author    = {Hulley, Glynn and Hook, Simon},
  title     = {{VIIRS/JPSS1} Land Surface Temperature/Emissivity Daily {L3} Global 1km {SIN} Grid Day {V002}},
  year      = {2023},
  publisher = {NASA Land Processes Distributed Active Archive Center},
  doi       = {10.5067/VIIRS/VJ121A1D.002}
}

VJ221A1D V002 (NOAA-21 daytime daily) — DOI 10.5067/VIIRS/VJ221A1D.002

@misc{vj221a1d_v002,
  author    = {Hulley, Glynn and Hook, Simon},
  title     = {{VIIRS/JPSS2} Land Surface Temperature/Emissivity Daily {L3} Global 1km {SIN} Grid Day {V002}},
  year      = {2026},
  publisher = {NASA Land Processes Distributed Active Archive Center},
  doi       = {10.5067/VIIRS/VJ221A1D.002}
}

Reference papers¶

VIIRS TES algorithm (Islam et al., 2017) — DOI 10.1109/TGRS.2016.2611566

@article{islam2017viirslst,
  author  = {Islam, Tanvir and Hulley, Glynn C. and Malakar, Nabin K. and Radocinski, Robert G. and Guillevic, Pierre C. and Hook, Simon J.},
  title   = {A Physics-Based Algorithm for the Simultaneous Retrieval of Land Surface Temperature and Emissivity From {VIIRS} Thermal Infrared Data},
  journal = {IEEE Transactions on Geoscience and Remote Sensing},
  volume  = {55},
  number  = {1},
  pages   = {563--576},
  year    = {2017},
  doi     = {10.1109/TGRS.2016.2611566}
}

MODIS–VIIRS TES LST continuity (Hulley et al., 2018) — DOI 10.1109/JSTARS.2017.2779330

@article{hulley2018modisviirs,
  author  = {Hulley, G. C. and Malakar, N. K. and Islam, T. and Freepartner, R. J.},
  title   = {{NASA}'s {MODIS} and {VIIRS} Land Surface Temperature and Emissivity Products: A Long-Term and Consistent Earth System Data Record},
  journal = {IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing},
  volume  = {11},
  number  = {2},
  pages   = {522--535},
  year    = {2018},
  doi     = {10.1109/JSTARS.2017.2779330}
}

Acknowledgements¶

Cite the LP DAAC dataset DOI of each product you used (pattern 10.5067/VIIRS/.002, e.g. 10.5067/VIIRS/VJ221A2.002 for NOAA-21 8-day). Cite Islam et al. (2017) for the algorithm and Hulley et al. (2018) for continuity with MODIS.

Information on the datasets used in this study was compiled with the help of the Korean Climate Data Navigator (KCDN) (Sim, 2026; https://doi.org/10.5281/zenodo.23300923).

Links¶

• VNP21A1D V002 data catalog (LP DAAC)
• VJ221A1D V002 data catalog (LP DAAC)
• VNP21 Collection 2 User's Guide
• VNP21 ATBD
• VIIRS Land — NASA land surface temperature and emissivity products
• VIIRS LST validation (VIIRS Land)
• Suomi NPP Data Product Delivery to Cease (Earthdata)