Ozone trends over the United States at different times of day
Data sets
Pre-Generated Data Files http://aqsdr1.epa.gov/aqsweb/aqstmp/airdata/download_files.html
Cold & Warm Episodes by Season http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml
AMO (Atlantic Multidecadal Oscillation) Index http://www.esrl.noaa.gov/psd/data/timeseries/AMO/