MODIS LST (MOD11·MOD21)¶

MODIS/Terra and Aqua Land Surface Temperature and Emissivity MOD11/MYD11 (split-window) and MOD21/MYD21 (TES) Version 6.1 (1 km day and night land surface temperature and emissivity from MODIS)

Being replaced

At a glance¶

Note on period: Terra (MOD11, MOD21) from 2000-02-24 (8-day and monthly products start with the periods beginning 2000-02-18 and 2000-02-01); Aqua (MYD11, MYD21) from 2002-07-04. On 2026-10-13 LP DAAC held data up to early to mid October 2026. Terra data from 2026-03-26 20:00 UTC to 2026-03-27 19:23 UTC were flagged as questionable or bad by the calibration team. A final reprocessing is planned once MODIS data collection ends.

Overview¶

Clear-sky land surface (skin) temperature and emissivity retrieved from the MODIS thermal infrared bands. Collection 6.1 contains two product families with different algorithms. MOD11/MYD11 use the generalized split-window method, based on the band 31–32 brightness temperature difference, with emissivity assumed from land cover classification, and screen out suspected cloudy pixels. MOD21/MYD21 use the ASTER-heritage temperature/emissivity separation (TES) method, which solves physically for band 29, 31 and 32 emissivity together with temperature; this reduces MOD11's 3–5 K cold bias over deserts and arid land, but unscreened hot outliers remain. There are separate Terra (morning and late evening) and Aqua (afternoon and early morning) versions, with daily, 8-day and monthly products on 1 km tiles and a 0.05° global grid.

What changes with the successor¶

MODIS LST C6 (MOD11 and MOD21) → MODIS LST C6.1¶

Transition: 2021-02

For MOD11 the science algorithm and file format are unchanged and the input L1B calibration improved. For MOD21 the atmospheric correction input changed from MERRA-2 (partly NCEP) to GEOS-5 FP, and new 0.05° global (CMG) products MxD21C1, C2 and C3 were added. Distribution of C6 ended on 2023-07-31.

Sources: MOD21A1D V061 collection description (version description) · MOD11 C6.1 User's Guide · MOD21 C6.1 User's Guide

MODIS LST MOD11 and MOD21 C6.1 → VIIRS LST VNP21, VJ121 and VJ221 V2 Planned¶

NASA's VIIRS land surface temperature products are VNP21 (Suomi NPP), VJ121 (NOAA-20) and VJ221 (NOAA-21) V2, made with the same TES algorithm and inputs as MOD21; the developers report that MODIS (MxD21) and VIIRS LST agree within about ±0.5 K. There is no NASA VIIRS product continuing the MOD11 split-window method, so MOD11 users also change algorithm. The transition completes when Terra and Aqua end, from late 2026 onward.

Sources: Hulley et al. (2018), IEEE JSTARS — MODIS and VIIRS LST consistency · VNP21 Collection 2 User's Guide · Transition from MODIS to VIIRS (Earthdata, 2025-05-02)

Compare the two side by side

Available variables¶

Science datasets (SDS) from the LP DAAC data catalog and the C6.1 User's Guides. In the HDF-EOS2 (HDF4) files, physical value = stored value × scale_factor (+ offset). LST uses scale 0.02 (K) and stored value 0 is fill. MYD (Aqua) files use the same names. MOD11 sets suspected contaminated pixels to fill, whereas MOD21 keeps their values, 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

MOD11 split-window — daily 1 km (MOD11A1, MYD11A1)¶

MOD11 split-window — 8-day and monthly (MOD11A2 1 km / MOD11C3 0.05°)¶

MOD21 TES — daily 1 km (MOD21A1D day / MOD21A1N night; same for MYD21)¶

MOD21 TES — 8-day and monthly (MOD21A2 1 km / MOD21C3 0.05°)¶

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: MOD11A1, MOD11A2, MOD11C1, MOD11C3, MOD11_L2, MOD21A1D, MOD21A1N, MOD21A2, MOD21C1, MOD21C3, MOD21 (L2); replace MOD with MYD for Aqua. All are version 061. Files are served over HTTPS from data.lpdaac.earthdatacloud.nasa.gov and need a free Earthdata Login. Distribution through the old LP DAAC Data Pool ended on 2025-06-30.
• 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; handy for comparisons with station points.
• Direct access in AWS us-west-2 (S3) — Cloud storage (S3, from within us-west-2 only)
  • Stored under paths such as s3://lp-prod-protected/MOD11A1.061/ and accessed with temporary credentials.

Example code¶

Downloads Terra MOD11A1 daily files with earthaccess, reads them with pyhdf and keeps only pixels whose mandatory QA (bits 0–1) is 'good' (00). Read the view time too, to check the effect of orbit drift.

# pip install earthaccess pyhdf numpy
import earthaccess
import numpy as np
from pyhdf.SD import SD, SDC

earthaccess.login()  # free NASA Earthdata account
results = earthaccess.search_data(
    short_name="MOD11A1", version="061",
    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, "mod11")

hdf = SD(files[0], SDC.READ)
lst = hdf.select("LST_Day_1km").get().astype("float64")
qc = hdf.select("QC_Day").get()
vt = hdf.select("Day_view_time").get().astype("float64")

good = (lst > 0) & ((qc & 0b11) == 0)        # drop fill + keep mandatory QA 'good'
lst_k = np.where(good, lst * 0.02, np.nan)    # K
view_time = np.where(vt < 255, vt * 0.1, np.nan)  # local solar time (hours)
print(np.nanmean(lst_k) - 273.15, np.nanmedian(view_time))

Practical tips¶

• MOD11 and MOD21 give different values for the same place and day. Over deserts, arid land and bare soil MOD11 can read 3–5 K low (cold bias), while MOD21 more often has hot outliers from unscreened dust and cloud contamination. Do not mix the two families in one study.
• MOD21 does not set contaminated pixels to fill. The User's Guide recommends screening with the QC bits (especially mandatory QA and LST accuracy), emissivity (band 31 or 32 below 0.95 is suspect) and the error estimates together.
• Because of orbit drift, the observation time has shifted year by year since 2020 (Terra) and 2021 (Aqua). For long-term trends and anomalies, look at Day_view_time / View_Time as well, and consider a time-of-day adjustment or selecting samples from the same time window.
• According to LP DAAC, the lower, drifting orbit reduces the grid size and breaks the strict 16-day repeat cycle, and later crossing times mean lower sun elevation and more shadows. The MODIS land QA team reports that impacts such as widening scan gaps became significant from late 2024.
• An official notice (2024-01) reports that Aqua MODIS band 29 brightness temperature has drifted upward since 2018 because of electronic crosstalk, making MYD21 land surface temperatures warmer than expected. Be careful with post-2018 trends from Aqua TES data.
• Terra MOD21 shows striping in L2 from 2006-08-29 because of a dead band 29 detector; those pixels are flagged in the QC bits and filled with nearest-neighbour values, so they must not be used for science.
• The 8-day and monthly products average clear days only and carry a clear-sky bias. In the cloudy monsoon season few days enter the average and representativeness drops.
• LST is surface (skin) temperature, not 2 m air temperature. It is much higher than air temperature at midday and lower on clear nights. Do not compare it directly with station air temperature.
• Value = stored value × 0.02 (K), with stored value 0 as fill. Emissivity = stored value × 0.002 + 0.49.

Notices and change history¶

References for your paper¶

Dataset citation¶

MOD11A1 V6.1 (Terra split-window daily) — DOI 10.5067/MODIS/MOD11A1.061

@misc{mod11a1_v061,
  author    = {Wan, Zhengming and Hook, Simon and Hulley, Glynn},
  title     = {{MODIS/Terra} Land Surface Temperature/Emissivity Daily {L3} Global 1km {SIN} Grid {V061}},
  year      = {2021},
  publisher = {NASA Land Processes Distributed Active Archive Center},
  doi       = {10.5067/MODIS/MOD11A1.061}
}

MOD11A2 V6.1 (Terra split-window 8-day) — DOI 10.5067/MODIS/MOD11A2.061

@misc{mod11a2_v061,
  author    = {Wan, Zhengming and Hook, Simon and Hulley, Glynn},
  title     = {{MODIS/Terra} Land Surface Temperature/Emissivity 8-Day {L3} Global 1km {SIN} Grid {V061}},
  year      = {2021},
  publisher = {NASA Land Processes Distributed Active Archive Center},
  doi       = {10.5067/MODIS/MOD11A2.061}
}

MOD21A1D V6.1 (Terra TES daytime daily) — DOI 10.5067/MODIS/MOD21A1D.061

@misc{mod21a1d_v061,
  author    = {Hulley, Glynn and Hook, Simon},
  title     = {{MODIS/Terra} Land Surface Temperature/3-Band Emissivity Daily {L3} Global 1km {SIN} Grid Day {V061}},
  year      = {2021},
  publisher = {NASA Land Processes Distributed Active Archive Center},
  doi       = {10.5067/MODIS/MOD21A1D.061}
}

MOD21A2 V6.1 (Terra TES 8-day) — DOI 10.5067/MODIS/MOD21A2.061

@misc{mod21a2_v061,
  author    = {Hulley, Glynn and Hook, Simon},
  title     = {{MODIS/Terra} Land Surface Temperature/3-Band Emissivity 8-Day {L3} Global 1km {SIN} Grid {V061}},
  year      = {2021},
  publisher = {NASA Land Processes Distributed Active Archive Center},
  doi       = {10.5067/MODIS/MOD21A2.061}
}

Reference papers¶

Generalized split-window algorithm (Wan & Dozier, 1996) — DOI 10.1109/36.508406

@article{wan1996splitwindow,
  author  = {Wan, Zhengming and Dozier, J.},
  title   = {A generalized split-window algorithm for retrieving land-surface temperature from space},
  journal = {IEEE Transactions on Geoscience and Remote Sensing},
  volume  = {34},
  number  = {4},
  pages   = {892--905},
  year    = {1996},
  doi     = {10.1109/36.508406}
}

MOD11 Collection 6 refinements and validation (Wan, 2014) — DOI 10.1016/j.rse.2013.08.027

@article{wan2014c6,
  author  = {Wan, Zhengming},
  title   = {New refinements and validation of the collection-6 {MODIS} land-surface temperature/emissivity product},
  journal = {Remote Sensing of Environment},
  volume  = {140},
  pages   = {36--45},
  year    = {2014},
  doi     = {10.1016/j.rse.2013.08.027}
}

Consistent TES retrievals for ASTER and MODIS (Hulley & Hook, 2011) — DOI 10.1109/TGRS.2010.2063034

@article{hulley2011tes,
  author  = {Hulley, Glynn C. and Hook, Simon J.},
  title   = {Generating Consistent Land Surface Temperature and Emissivity Products Between {ASTER} and {MODIS} Data for Earth Science Research},
  journal = {IEEE Transactions on Geoscience and Remote Sensing},
  volume  = {49},
  number  = {4},
  pages   = {1304--1315},
  year    = {2011},
  doi     = {10.1109/TGRS.2010.2063034}
}

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/MODIS/.061, e.g. 10.5067/MODIS/MYD11A1.061 for Aqua daily). Cite Wan & Dozier (1996) and Wan (2014) for MOD11, and Hulley & Hook (2011) with the MOD21 ATBD for MOD21.

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¶

• MOD11A1 V061 data catalog (LP DAAC)
• MOD21A1D V061 data catalog (LP DAAC)
• MOD11 C6.1 User's Guide
• MOD21 C6.1 User's Guide
• MOD21 ATBD
• Aqua MODIS Acquisition Plan Through August 2026 (LP DAAC, orbit drift schedule)
• Terra mission home page (equator crossing time and altitude)
• MODIS/VIIRS Land Quality Assessment (LDOPE) known issues