ASTER Cloud Mask Database

Hokkaido, Japan, at 12:36:57 on 3 Sep. 2005 UTC (050903123657). Left: ASTER scene (nighttime), Right: MOD35-based 1km-res. cloud mask
Cloud assessment of satellite imagery is important for image search and higher-level processing. Unfortunately, the cloud assessment algorithm of ASTER is not accurate particularly for non-full-mode observations such as nighttime observation and V-only-mode observation, and also for all daytime observations after April 2008 when ASTER shortwave infrared bands stopped due to a trouble in their temperature control. Thus, we are generating more accurate cloud masks for all ASTER scenes over 1.6 million scenes and provide them here. All reassessment results are transferred to ASTER Ground Data System (GDS) every day, and then input to the database used for ASTER image search. Because a cloud mask provided here is adjusted for an original L1A scene, you need to rotate the mask by 180 degrees. If your product is not in Level 1A (that is, Level 1B/2/3A), you need to adjust the provided mask to your image geometrically based on the four corner positions of the mask.

H. Tonooka, K. Omagari, H. Yamamoto, T. Tachikawa, M. Fujita, and Z. Paitaer, ASTER cloud coverage reassessment using MODIS cloud mask products, Proc. of SPIE, 7862, 2010.
H. Tonooka, ASTER nighttime cloud mask database using MODIS cloud mask (MOD35) products, Proc. SPIE, 7107, 2008.

Notite: In original processing, MOD35 Collection 5 was used. Reprocessing using MOD35 Collection 6 is now on going. Collection number used is displayed in the next page.

Cloud Mask Search
(1) Input the observation time of your ASTER data in YYMMDDhhmmss:
   (ex. 090907012712 for ASTL1A 0909070127120909130641)
(2) Check if you want to rotate the mask by 180 degrees:

Contact: Dr. Hideyuki Tonooka
Prof. of Ibaraki Univ., Japan
ASTER Science Team Member