40 CFR § 1065.630 - Local acceleration of gravity.
(a) The acceleration of Earth's gravity, ag, varies depending on the test location. Determine ag at your location by entering latitude, longitude, and elevation data into the U.S. National Oceanographic and Atmospheric Administration's surface gravity prediction Web site at http://www.ngs.noaa.gov/cgi-bin/grav__pdx.prl.
(b) If the Web site specified in paragraph (a) of this section is unavailable, you may calculate ag for your latitude as follows:
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