Products/Data - Global Cloud Mask
The global cloud product is based on data combined from GOES, AVHRR, and MODIS. GOES data are used for high temporal resolution in the midlatitudes, and AVHRR and MODIS data are used to estimate cloudiness over the polar regions, thus creating a global product. This product uses a single wavelength (11 micron) to determine cloud/no cloud classifications globally. This technique is particularly useful for sensing high and middle clouds, however, may miss low clouds and fog. Cloud top height is determined by comparing the 11 micron brightness temperature to a model temperature profile. Data files are in ncdf format, and currently provide the following information:
- 11 micron brightness temperature
- CTH (Cloud -top height, in ft)
- Binned CTH (0-10K ft, 10K-20K ft, 20K-30K ft, 30K-40K ft, and above 40K ft.)
- Time latency, or the time at which any pixel was last updated
This product updates itself whenever new data becomes available. GOES products come in roughly every 15 minutes, however, MODIS and AVHRR update much less frequently. Some discontinuities in brightness temperature do exist between the different instruments, due to the differences in the instrument calibration. However, this should be a useful tool in identifying regions where clouds could be an issue at flight level. This product is archived at CIMSS hourly.
FTP site for data: ftp://ftp.ssec.wisc.edu/asap/products/global_clouds/