Hello Ecolog-gers! Anyone have ideas on how to calculate accumulated degree days for a larger dataset?
The data I'm working with consists of daily maximum and minimum air temperature readings from a few score of sites across Pennsylvania over the last 20 years. What I want to do is to calculate accumulated degree days for each year at each site. I'm going with calendar year for simplicity's sake. I know how to calculate degree days, it's the accumulation part I'm stumbling on. And I know how to sum degree days for each year and each station - that's easy. I also know how to calculate time-lagged running averages, but that's not really what I'm aiming for here. I want the degrees days to accumulate each successive (Julian) day at each station for each year, and to start over accumulating for each new station and/or year combination. That is to say, for 1 May 2008 at the Chalk Hill site, I want to sum all the degree days from 1 January 2008 to 30 April 2008 at that site. The only way I'm presently aware of to do this is "by hand" in Excel, and that's not really practical given the size of the dataset I'm working with and temporal allocation considerations imposed by mortality. Does any one know of a script (R? SAS?) to do this? I can envision some, but they get unwieldy pretty quick. Or is a way this can be done with a database query? Any thoughts would be much appreciated! Smiles =] Brian Brian A. Chalfant | -ologist Pennsylvania Department of Environmental Protection Rachel Carson State Office Building 400 Market Street | Harrisburg, PA 17101 Phone: 717.787.9639 | Fax: 717.772.3249 www.depweb.state.pa.us<http://www.depweb.state.pa.us/>
