STAR MODIS Cloud Satellite Dataset

The changing climate represents one of the most important ecological issues concerning our planet. Changes in atmospheric trace gases, cloud over, cloud type, solar radiation, and tropospheric aerosols (liquid or solid particles suspended in the air) can have a profound impact on the climatic system as each property can modify the climate through changes in the radiative forcings. As such, it is important to correctly represent the climate and the associated forcings in conceptual and predictive global models. In an effort to monitor these properties, two MODIS (Moderate Resolution Imaging Spectroradiometer) instruments, the first launched on 18 December 1999 onboard the Terra Satellite Platform and the second on 4 May 2002 onboard the Aqua Satellite platform, were uniquely designed to observe and monitor these and other Earth changes on a global scale.

A thorough description of global cloudiness and its associated properties 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 in order to assess climate and potential climate change accurately. In addition, the presence or absence of cloudiness must be accurately determined in order to retrieve properly many atmospheric and surface parameters, including phase, optical thickness, and temperature. These and other cloud parameters are retrieved at a high resolution, allowing many details and fine features to be resolved accurately.

The MODIS Cloud Product combines infrared and visible techniques to determine both physical and radiative cloud properties. Daily global Level 2 data are provided. Cloud-particle phase (ice vs. water, clouds vs. snow), effective cloud-particle radius, and cloud optical thickness are derived using the MODIS visible and near-infrared channel radiances. Cloud-top temperature, height, effective emissivity, phase (ice vs. water, opaque vs. non-opaque), and cloud fraction are produced by the infrared retrieval methods both day and night at 5 × 5 1-km-pixel resolution. Finally, the MODIS Cloud Product includes the cirrus reflectance in the visible at the 1-km-pixel resolution, which is useful for removing cirrus scattering effects from the land-surface reflectance product. There are two MODIS Cloud data product files: MOD06_L2, containing data collected from the Terra platform; and MYD06_L2, containing data collected from the Aqua platform.

For further details see the NASA MODIS home page:

http://modis-atmos.gsfc.nasa.gov/MOD06_L2/index.html)