For further understanding of the 'Total Earth System' and the effects of natural and human-induced changes on the global environment, MODIS was launched aboard the Terra satellite on December 18, 1999 (10:30 am equator crossing time) as part of NASA's Earth Observing System (EOS) mission. MODIS with its 2330 km viewing swath width provides almost daily global coverage. It acquires data in 36 high spectral resolution bands between 0.415 and 14.235 µm with spatial resolutions of 250 m (2 bands), 500 m(5 bands), and 1000 m (29 bands). This year a similar instrument will be flown on the EOS-Aqua satellite (1:30 pm equator crossing time). This will enable us to study diurnal variation of the rapidly varying systems and will also provide us with a long term dataset for the same set of geophysical parameters for the study of climate and global change studies.

MODIS raw radiance counts, calibrated radiances, geolocation products and all derived geophysical atmospheric and ocean products are archived at the Goddard Earth Sciences Data and Information Services Center (GES DISC) Distributed Active Archive Center (DAAC) and are freely made available (http://daac.gsfc.nasa.gov/) to the public and science user community.

MODIS Atmospheric Products distributed by the Goddard DAAC include: Atmospheric Aerosols (aerosol type over land, optical thickness and Angstrom exponent over land and ocean, particle size parameters, and ratio of small and large particles over ocean, and many model parameters), Cloud (optical thickness, effective radius, cloud phase, water path, cloud top temperature, pressure, effective emissivity, cloud fraction, cirrus reflectance, spectral cloud forcing, brightness temperature), Total Precipitable Water Vapor (infrared and near infrared estimates), Atmospheric Profiles (temperature, moisture and geopotential height at 20 pressure levels, total ozone, atmospheric stability indices), and Cloud Mask (parameter distinguishing clear sky from clouds, identifying cloud shadow, sun-glint, land/water, snow/ice, day/night).

In spite of the fact that current data products are of 'provisional' quality (validation activities and calibration algorithm enhancements are in progress), MODIS Science Team Members have shown that the quality of radiances and derived geophysical parameters are exceptionally good when compared to products derived from existing heritage sensors (AVHRR, GOES, Meteosat) and other in situ observations.

This presentation will provide highlights of the MODIS atmospheric products and demonstrate the quality of these products by presenting some examples of the atmospheric parameters.