Will aerosol measurements from Terra and Aqua polar orbiting satellites represent the daily aerosol abundance and properties?

The Terra and Aqua missions will help quantify aerosol radiative forcing of climate by providing innovative measurements of the aerosol daily spatial distribution and identifying dust, smoke and regional pollution. However, t hese measurements are acquired at specific times of the day. To what extent can such measurements represent the daily average aerosol forcing of clima te? We answer this question using 7 years of data from the Aerosol Robotic Network (AERONET) of 50-70 global ground-based instruments. AERONET measure s the aerosol spectral optical thickness and the total precipitable water v apor every 15 minutes throughout the day. With a data set of 1/2 million me asurements, AERONET demonstrates that Terra and Aqua aerosol measurements c an represent the annual average value within 2% error. This excellent Terra representation of the daily average optical thickness is independent of th e particle size or range of the optical thickness. This finding should faci litate ingest of satellite aerosol measurements in models that calculate ra diative forcing and predict climate change.