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Cloud Mask

Cloud Mask Products

Cloud Mask

The Cloud Mask Product indicates whether a given instrument field of view (FOV) of the Earth's surface is unobstructed by clouds or affected by cloud shadows. The cloud mask also provides additional information about the FOV including the presence of: cirrus clouds, ice/snow, and sunglint contamination. Finally flags denoting day/night and land/water are included. The ESDT names are MOD35_L2 (Terra) and MYD35_L2 (Aqua).

Missing Terra Data between 5 Aug 2017 and 6 Aug 2017

Description: Following the Terra Deep Space Calibration on August 5th, 2017 (2017 217) there were some faulty C6 Terra MODIS Atmosphere data as the focal plane temperatures did not return to nominal values until the day after - August 6th, 2017 (2017 218) 1420 UTC. So the granules for the time period between 2017 217 23:00 UTC and 2017 218 14:15 UTC were removed before the downstream Atmosphere processing. Data users will notice missing MODIS Atmosphere Data during this period for all Level-2 (L2) and Level-3 (L3) Daily atmosphere products.

Cloud Mask not detecting high thick clouds over Weddell Sea (Antarctica) when ice covered

In collection 006, the cloud mask is failing to detect high thick clouds over the Weddell Sea area in Antarctica when it is ice-covered. This represents a small area over very dry conditions. This problem might be fixed in a future PGE03 delivery, until then users should be aware of this shortcoming.

PGE Versions & Production Dates of Problematic & Corrected Data:

Steve Platnick

MODIS Atmosphere Team Lead

Sample Images

Cloud Mask Movie Loops

Click to download a Quicktime movie player

A program to produce QuickTime movie loops of the MODIS Cloud and Land/Sea Mask results for all MOD35_L2 granules retrieved for a single data day was developed by Jason Li (NASA GSFC). Also displayed in the movie is an 11 micron reverse-scale image for nighttime granules or a .65 micron image for daytime granules.


Key MODIS Scientific Publications

  Cloud Mask

  • Frey, R. A., S. A. Ackerman, Y H. Liu, K. I. Strabala, H. Zhang, J. R. Key, and X. G. Wang, 2008: Cloud detection with MODIS. Part I: Improvements in the MODIS cloud mask for collection 5. J. Atmos. Oceanic Technol., 25(7), 1057-1072.  View PDF