Steve, I don't want you to go to alot of trouble. I was just asking to get a sense of what the program is capable of doing. I will be working with historical data - thus, my preference for analyzed fields. I am working with the air pollution people here to provide some background for field measurements they did April 1999 in southeast Kansas. I would be looking at periods of about 24 hours at a time. Donna Tucker http://chinook.phsx.ukans.edu/tucker.html address@hidden Department of Physics and Astronomy (785) 864-4738 (new area code!) University of Kansas (785) 864-5262 (fax) Lawrence, KS 66045-2151