This is a page to view geomaps of Average Daily Noise Level (DNL) values across the mid-peninsula area of San Francisco, covering a one-week period from Sunday, 12/10/2017 through Saturday, 12/16/2017. For each day, DNL geomaps are computed for a 24-hour period and four 6-hour periods: 0:00 – 6:00; 6:00 – 12:00; 12:00 – 18:00; and 18:00 – 24:00. This slideshow is organized such that the time-slice DNL geomaps for each day are presented in sequence.
Some of the things to notice in the geomaps are: (a) the 24-hr DNL geomap averages out many important features of the overflight traffic varying during the day and (b) the traffic patterns change dramatically during the day. These differences in various parts of the day and from day to day suggest why it is so hard to pin down explanations for why aircraft noise appears to abate from time to time and then returns in highly annoying clusters.
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