# 40 CFR § 1065.630 - Local acceleration of gravity.

§ 1065.630 Local acceleration of gravity.
Link to an amendment published at 88 FR 4680, Jan. 24, 2023.

(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:

$\begin{array}{c}{a}_{g}=9.7803267715·\left[1+5.2790414·{10}^{-3}·{\mathrm{sin}}^{2}\left(\theta \right)+2.32718·{10}^{-5}·{\mathrm{sin}}^{4}\left(\theta \right)\\ +1.262·{10}^{-7}·{\mathrm{sin}}^{6}\left(\theta \right)+7·{10}^{-10}·{\mathrm{sin}}^{8}\left(\theta \right)\right]\\ \text{Eq. 1065.630-1}\end{array}$

Where:
u = Degrees north or south latitude.
Example:
u = 45°
ag = 9.7803267715 · (1 + 5.2790414 · 10−3 · sin 2 (45) + 2.32718 · 10−5 · sin 4 (45) + 1.262 · 10−7 · sin 6 (45) + 7 · 10−10 · sin 8 (45)
ag = 9.8061992026 m/s 2
[79 FR 23784, Apr. 28, 2014]