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GODDARD EARTH SCIENCES UPDATE 
JANUARY 5, 2001 
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Earth Sciences Directorate
Goddard Space Flight Center
Greenbelt, MD  20771  (301) 614-5634
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Goddard Earth Sciences Update" is a weekly bulletin to keep 
management apprised of the latest accomplishments of Goddard's Earth 
Sciences Directorate.   This newsletter is also accessible at 
http://www.gsfc.nasa.gov/    Please forward comments or suggestions 
to: Lynn Chandler (301) 614-5562  or  Debra. 
L.Chandler.1@gsfc.nasa.gov
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In this Issue:  AEROSOL MEASUREMENTS FROM TERRA AND AQUA 

The   Terra   and   Aqua   missions  will  help quantify aerosol 
effect on solar radiation and climate by providing innovative 
measurements of the aerosol daily spatial distribution and 
identifying dust, smoke and regional pollution. However, these 
measurements are acquired at specific times of the day. To what 
extent can such measurements represent the daily average aerosol 
properties and eeffect on climate?

This question is answered using 7 years of data from the Aerosol 
Robotic Network (AERONET) of 50-70 global ground-based instruments. 
AERONET measures the aerosol spectral optical thickness and the total 
precipitable water vapor every 15 minutes throughout the day. With a 
data set of 1/2 million measurements, AERONET demonstrates that Terra 
and Aqua aerosol measurements can represent the annual average value 
within 2% error.

This excellent Terra representation of the daily average optical 
thickness is independent of the particle size or range of the optical 
thickness. This finding should facilitate ingest of satellite aerosol 
measurements in climate models that calculate the present aerosol 
effect and future climate change.

Reference:   This paper has been accepted for publication in 
Geophysical Research Letters

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For further information contact:
Yorum Kaufman, Code 913
(301) 614-6189
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