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MOD35_L2 - MODIS/Terra Cloud Mask and Spectral Test Results 5-Min L2 Swath 250m and 1km

Update Frequency: As Needed
Latest Data Update: 2023-06-19
Status: Ongoing
Online Status: ONLINE
Publication State: Published
Publication Date: 2021-04-15
Download Stats: last 12 months
Dataset Size: 2.42M Files | 17TB


These data are a copy of MODIS data from the NASA Level-1 and Atmosphere Archive & Distribution System (LAADS) Distributed Active Archive Center (DAAC). The copy is potentially only a subset. Below is the description from

The MODIS Cloud Mask product is a Level-2 product generated at 1-km and 250-m (at nadir) spatial resolutions. The algorithm employs a series of visible and infrared threshold and consistency tests to specify confidence that an unobstructed view of the Earth's surface has been observed. An indication of shadows affecting the scene is also provided. The 250-m cloud mask flags are based on visible channel data only. Radiometrically-accurate radiances are required, thus holes in the Cloud Mask will appear wherever the input radiances are incomplete or of poor quality assurance. There are two MODIS Cloud Mask data product files: MOD35_L2, containing data collected from the Terra platform; and MYD35_L2, containing data collected from the Aqua platform.

The MODIS cloud mask algorithm employs a battery of spectral tests, which use methodology applied in the AVHRR Processing scheme Over cLoudy Land and Ocean (APOLLO), International Satellite Cloud Climatology Project (ISCCP), CLoud Advanced Very high resolution Radiometer (CLAVR), and the Support of Environmental Requirements for Cloud Analysis and Archive (SERCAA) algorithms to identify cloudy FOVs. From these, a clear-sky confidence level (high confident clear, probably clear, undecided, cloudy) is assigned to each FOV. For inconclusive results, spatial- and temporal-variability tests are applied. The spectral tests rely on radiance (temperature) thresholds in the infrared and reflectance thresholds in the visible and near-infrared. Thresholds vary with surface type, atmospheric conditions (moisture, aerosol, etc.), and viewing geometry. In addition to the MOD02 calibrated radiances, a 1-km land/water mask, DEM, ecosystem analysis, snow/ice cover map, NCEP analysis of surface temperature and wind speed, and an estimate of precipitable water are required as inputs.

A determination of the presence of global cloudiness is essential to the MODIS mission for two reasons. First, clouds play a critical role in the radiative balance of the Earth and must be accurately described to assess climate and potential climate change. Second, the presence of cloudiness must be accurately determined to properly retrieve many atmospheric and surface parameters. For many of these retrieval algorithms even thin cirrus represents contamination.

Cloud mask validation will be conducted using MODIS Airborne Simulator (MAS) data from several field campaigns, all-sky cameras, and comparison with NOAA operational instruments and possibly ASTER.

For additional details see the MODIS Atmospheres web site page onCollection 6.1 Updates. "

Shortname: MOD35_L2 , Platform: Terra , Instrument: MODIS , Processing Level: Level-2 , Spatial Resolution: 250 m, 1 km , Temporal Resolution: 5 minute , ArchiveSets: 61 , Collection: MODIS Collection 6.1 - Level 1, Atmosphere, Land (ArchiveSet 61) , PGE Number: PGE03 , File Naming Convention: MOD35_L2.AYYYYDDD.HHMM.CCC.YYYYDDDHHMMSS.hdf YYYYDDD = Year and Day of Year of acquisition HHMM = Hour and Minute of acquisition CCC = Collection number YYYYDDDHHMMSS = Production Date and Time AYYYYDDD = Year and Day of Year of acquisition , Citation: Ackerman, S., et al., 2015. MODIS Atmosphere L2 Cloud Mask Product. NASA MODIS Adaptive Processing System, Goddard Space Flight Center, USA: , Keywords: Cloud Fraction, Climate Change, Atmospheric Correction

Citable as:  National Aeronautics and Space Administration (2021): MOD35_L2 - MODIS/Terra Cloud Mask and Spectral Test Results 5-Min L2 Swath 250m and 1km. National Aeronautics and Space Administration, date of citation.
Abbreviation: MOD35_L2
Keywords: Cloud Fraction, Climate Change, Atmospheric Correction


Previous Info:
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Previously used record identifiers:
No related previous identifiers.
Access rules:
Public data: access to these data is available to both registered and non-registered users.
Use of these data is covered by the following licence: When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record.
Data lineage:

Data were downloaded from to support UK research groups, especially NCEO.

Data Quality:
Look on the data source site ( for quality information
File Format:

Process overview

This dataset was generated by instruments deployed on platforms as listed below.

Mobile platform operations

Mobile Platform Operation 1 Terra Satellite orbit details
Output Description


  • units: percent
  • var_id: Cloud_Mask_SPI
  • long_name: Dispersion in bands 1 (plane 1) and 2 (plane 2) from 250m reflectance statistics of cloud mask
  • units: degrees_north
  • var_id: Latitude
  • long_name: Geodetic Latitude
  • units: degrees_east
  • var_id: Longitude
  • long_name: Geodetic Longitude
  • units: none
  • var_id: Cloud_Mask
  • long_name: MODIS Cloud Mask and Spectral Test Results
  • units: none
  • var_id: Quality_Assurance
  • long_name: Quality Assurance for Cloud Mask
  • units: degrees
  • var_id: Sensor_Azimuth
  • long_name: Sensor Azimuth Angle, Cell to Sensor
  • units: degrees
  • var_id: Sensor_Zenith
  • long_name: Sensor Zenith Angle, Cell to Sensor
  • units: degrees
  • var_id: Solar_Azimuth
  • long_name: Solar Azimuth Angle, Cell to Sun
  • units: degrees
  • var_id: Solar_Zenith
  • long_name: Solar Zenith Angle, Cell to Sun
  • units: seconds
  • var_id: Scan_Start_Time
  • long_name: TAI time at start of scan replicated across the swath

Co-ordinate Variables

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