MODIS Cloud (MOD06·MOD35)¶

MODIS/Terra and Aqua Clouds 5-Min L2 Swath 1km and 5km (MOD06_L2, MYD06_L2), Cloud Mask and Spectral Test Results (MOD35_L2, MYD35_L2) and MOD08/MYD08 L3 1° cloud, Collection 6.1 (MODIS cloud mask, cloud top and optical properties)

Being replaced

At a glance¶

Note on period: Terra (MOD06, MOD35, MOD08) from 2000-02-24; Aqua (MYD06, MYD35, MYD08) from 2002-07-04. On 2026-10-13 LAADS held data up to early October 2026 (MOD08_D3 A2026282). C6.1 was reprocessed for the full record from September to December 2017 (Terra) and January to March 2018 (Aqua); since 30 April 2018 only C6.1 has been produced.

Overview¶

NASA's standard cloud products made from the 36 MODIS bands. MOD35 is a cloud mask that combines visible and infrared threshold tests into a per-pixel confidence that the view is clear. MOD06 holds cloud top pressure, temperature, height and infrared phase, retrieved with the CO2 absorption bands (CO2 slicing) and the infrared window, plus cloud optical thickness, effective particle radius and water path from visible and shortwave infrared reflectance (daytime). MOD08 L3 gathers these into daily, 8-day and monthly statistics on a 1° grid, in the same files as aerosol, water vapour and atmospheric profile statistics. There are separate Terra (morning) and Aqua (afternoon) versions. Because the algorithms use CO2 and water vapour absorption bands that only MODIS has, they cannot simply be carried over to VIIRS.

What changes with the successor¶

MODIS clouds C6 (MOD06, MOD35, MOD08) → MODIS clouds C6.1¶

Transition: 2018-03

A reprocessing that fixed problems in the input L1B data; changes to the cloud products are mostly small (ancillary inputs, QA, handling of cloud top fill values). C6.1 fixed false ocean clouds caused by Terra band 29 calibration drift and the C6 December bias in low-cloud pressure over ocean. Since 30 April 2018 only C6.1 has been produced.

Sources: MODIS Atmosphere — Data Versions (collections overview) · MODIS Cloud (06_L2) known issues · C6.1 cloud optical properties change summary

MODIS clouds MOD06, MOD35, MOD08 C6.1 → MODIS-VIIRS continuity cloud products CLDMSK and CLDPROP Planned¶

VIIRS lacks the MODIS CO2 absorption bands (around 13 µm) and water vapour bands (6.7 and 7.3 µm), and its shortwave infrared band is at 2.25 µm instead of 2.13 µm, so MOD06 and MOD35 cannot be ported directly. NASA therefore built a cloud mask (CLDMSK) and cloud properties (CLDPROP) with algorithms that use only bands common to both sensors, applied in the same way to VIIRS (Suomi NPP, NOAA-20) and to Aqua MODIS. The key point is the Aqua MODIS CLDPROP, which remakes the MODIS record with the same algorithm so it can be joined to VIIRS.

Sources: Platnick et al. (2021), Remote Sensing — The NASA MODIS-VIIRS Continuity Cloud Optical Properties Products · LAADS DAAC — MODIS to VIIRS Transition (continuity product table) · MODIS-VIIRS Cloud Mask (MVCM) User Guide

Compare the two side by side

Available variables¶

SDS names and units from the CMR variable records (UMM-Var). Files are HDF-EOS2 (HDF4) with integer storage, so physical value = scale_factor × (stored value − add_offset) (the MODIS Atmosphere definition; add_offset is subtracted). For example Cloud_Top_Temperature has scale 0.01 and add_offset −15000, so the physical value is 0.01 × (stored value + 15000) K. MYD (Aqua) files use the same names.

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

L2 cloud mask 1 km (MOD35_L2, MYD35_L2)¶

L2 cloud top and phase (MOD06_L2, MYD06_L2)¶

L2 cloud optical properties 1 km, daytime (MOD06_L2, MYD06_L2)¶

L3 daily 1° (MOD08_D3, MYD08_D3)¶

L3 8-day and monthly 1° (MOD08_E3 8-day / MOD08_M3 monthly)¶

The full variable list is in the official documentation.

How to get the data¶

• LAADS DAAC (search, order and direct download) — Web search, direct HTTPS download (archive/allData/61//) / LAADS API-V2 / OPeNDAP
  • Example short names: MOD06_L2, MYD06_L2, MOD35_L2, MYD35_L2, MOD08_D3, MOD08_E3, MOD08_M3 (MYD for Aqua). All are C6.1 (archive 61; CMR version "6.1"). Since 2026-04-30 OPeNDAP also requires Earthdata Login, and the old LAADS Classic API was retired on 2026-08-31, so scripts must move to API-V2.
• NASA Earthdata Search — Web search / earthaccess (Python)
  • The link points to MOD06_L2 C6.1; search other products by short name. Files are also served from Earthdata Cloud.
• Worldview (imagery) — Web map
  • Shows MODIS cloud product imagery by date, which helps when choosing case studies.

Example code¶

Downloads an Aqua MYD08_M3 monthly file with earthaccess and reads the monthly mean cloud fraction with pyhdf. MODIS atmosphere products subtract add_offset from the stored value before multiplying by scale_factor, so convert by hand.

# 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="MYD08_M3", version="6.1",
    temporal=("2024-07-01", "2024-07-31"),
)
files = earthaccess.download(results[:1], "myd08")

hdf = SD(files[0], SDC.READ)
sds = hdf.select("Cloud_Fraction_Mean_Mean")
raw = sds.get().astype("float64")
att = sds.attributes()
cf = np.where(raw == att["_FillValue"], np.nan,
              att["scale_factor"] * (raw - att["add_offset"]))  # 1° grid, 180×360
lat = 89.5 - np.arange(180)                     # row 0 = 89–90°N
w = np.cos(np.deg2rad(lat))[:, None] * np.ones((1, 360))
ok = np.isfinite(cf)
print("Global area-weighted cloud fraction:", (cf[ok] * w[ok]).sum() / w[ok].sum())

Practical tips¶

• 'Cloud fraction' means different things in different fields. L3 Cloud_Fraction_Mean is the share of 'cloudy + probably cloudy' pixels in the cloud mask, while Cloud_Retrieval_Fraction_* is the share of pixels with a successful optical property retrieval. Match the definition when comparing with ISCCP or reanalysis cloud cover.
• Optical thickness, effective radius and water path exist only in daytime, and only where cloud fills the pixel and the retrieval succeeds. Polar night, high-latitude winter with large solar zenith angles, and regions with much thin cirrus have few samples and may be biased.
• Cloud top properties come at 5 km (Cloud_Top_Pressure) and 1 km (cloud_top_pressure_1km). The MODIS Atmosphere team recommends the 1 km products for new work, but L3 statistics are still built from the 5 km L2.
• In the HDF4 files the physical value is scale_factor × (stored value − add_offset). With a variable like Cloud_Top_Temperature, whose add_offset is −15000, getting the sign wrong gives nonsense instead of about 300 K.
• The MODIS Atmosphere known issues list notes that warming of Aqua band 29 (8.6 µm) has created artificial trends in the Aqua C6.1 infrared cloud phase (largest in the tropics), and that Aqua 5 km cloud top data over southern Africa between 09:00 and 12:30 UTC are intermittently missing.
• A Terra part failure (PWA) on 5 October 2020 removed visible and near-infrared reflectance in some high-latitude scenes, creating false clouds in the daytime polar and subpolar cloud mask. MOD35 and MOD06 for 2020-10-05 to 2021-09-25 were reprocessed with updated algorithms, so use the reprocessed files for that period (check the production date).
• After NOAA stopped producing Reynolds SST in December 2022, MOD35 and MOD06 kept using the last Reynolds SST (week of 2022-11-27), according to a LAADS notice. Whether a replacement SST was applied and the period reprocessed could not be confirmed from notices as of 2026-10-13, so take care with ocean cloud mask and low cloud top analyses after December 2022.
• The MODIS Atmosphere issues list has a 'C7.0 Cloud L3' entry (updated 2026-09), but on 2026-10-13 no MODIS C7 cloud products were public in CMR or at LAADS. Check LAADS notices for a release.

Notices and change history¶

References for your paper¶

Dataset citation¶

MOD06_L2 C6.1 (Terra L2 clouds) — DOI 10.5067/MODIS/MOD06_L2.061

@misc{mod06_l2_c61,
  author    = {Platnick, S. and Ackerman, S. and King, M. and others},
  title     = {{MODIS} Atmosphere {L2} Cloud Product (06\_L2)},
  year      = {2015},
  publisher = {NASA MODIS Adaptive Processing System, Goddard Space Flight Center, USA},
  doi       = {10.5067/MODIS/MOD06_L2.061}
}

MOD35_L2 C6.1 (Terra L2 cloud mask) — DOI 10.5067/MODIS/MOD35_L2.061

@misc{mod35_l2_c61,
  author    = {Ackerman, S. and others},
  title     = {{MODIS} Atmosphere {L2} Cloud Mask Product},
  year      = {2015},
  publisher = {NASA MODIS Adaptive Processing System, Goddard Space Flight Center, USA},
  doi       = {10.5067/MODIS/MOD35_L2.061}
}

MOD08_D3 C6.1 (Terra L3 daily) — DOI 10.5067/MODIS/MOD08_D3.061

@misc{mod08_d3_c61,
  author    = {Platnick, S. and others},
  title     = {{MODIS} Atmosphere {L3} Daily Product},
  year      = {2015},
  publisher = {NASA MODIS Adaptive Processing System, Goddard Space Flight Center, USA},
  doi       = {10.5067/MODIS/MOD08_D3.061}
}

MOD08_M3 C6.1 (Terra L3 monthly) — DOI 10.5067/MODIS/MOD08_M3.061

@misc{mod08_m3_c61,
  author    = {Platnick, S. and others},
  title     = {{MODIS} Atmosphere {L3} Monthly Product},
  year      = {2015},
  publisher = {NASA MODIS Adaptive Processing System, Goddard Space Flight Center, USA},
  doi       = {10.5067/MODIS/MOD08_M3.061}
}

Reference papers¶

MODIS cloud optical and microphysical products, C6 (Platnick et al., 2017) — DOI 10.1109/TGRS.2016.2610522

@article{platnick2017c6,
  author  = {Platnick, S. and Meyer, K. and King, M. D. and Wind, G. and Amarasinghe, N. and Marchant, B. and Arnold, G. T. and Zhang, Z. and Hubanks, P. A. and Holz, R. E. and Yang, P. and Ridgway, W. L. and Riedi, J.},
  title   = {The {MODIS} cloud optical and microphysical products: {Collection 6} updates and examples from {Terra} and {Aqua}},
  journal = {IEEE Transactions on Geoscience and Remote Sensing},
  volume  = {55},
  pages   = {502--525},
  year    = {2017},
  doi     = {10.1109/TGRS.2016.2610522}
}

MODIS cloud top property refinements for C6 (Baum et al., 2012) — DOI 10.1175/JAMC-D-11-0203.1

@article{baum2012c6,
  author  = {Baum, B. A. and Menzel, W. P. and Frey, R. A. and Tobin, D. C. and Holz, R. E. and Ackerman, S. A. and Heidinger, A. K. and Yang, P.},
  title   = {{MODIS} cloud-top property refinements for {Collection 6}},
  journal = {Journal of Applied Meteorology and Climatology},
  volume  = {51},
  pages   = {1145--1163},
  year    = {2012},
  doi     = {10.1175/JAMC-D-11-0203.1}
}

Acknowledgements¶

Cite the LAADS dataset DOI of each product you use (pattern 10.5067/MODIS/.061, e.g. 10.5067/MODIS/MYD06_L2.061 for Aqua clouds and 10.5067/MODIS/MOD08_E3.061 for the 8-day product). Cite Platnick et al. (2017) for cloud optical properties, Baum et al. (2012) for cloud top properties, and the MOD35 ATBD (Ackerman et al.) and Frey et al. (2008, J. Atmos. Oceanic Technol., 25, 1057–1072) for the cloud mask.

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¶

• MOD06_L2 product page (LAADS DAAC)
• MOD35_L2 product page (LAADS DAAC)
• MOD08_M3 product page (LAADS DAAC)
• MODIS Cloud Optical Properties User's Guide (C6 and C6.1)
• MOD35 cloud mask user's guide
• MODIS Atmosphere L3 User's Guide & ATBD (C6 and C6.1)
• MODIS Atmosphere — Cloud (06_L2) known issues
• LAADS DAAC — MODIS to VIIRS Transition