Re: database of accel due to gravity

[Larry Smith <Larry.Smith@SNOW.EDU>]

> I'd like to find a reference where you punch in a location and it gives you
> the local value for the acceleration due to gravity (the gravitational field
> strength).  I presume something like this exists on-line somewhere, but I
> haven't been able to find it.  Does anyone know of such a thing?
>
> I have some students working on a project where they are measuring the value
> for g at various different altitudes and latitudes.  There are some
> travelers in this group, so it seems like a nice study.  I'm letting them
> find out the difficulty of nailing down a third significant figure, but I'd
> like some reference values for making comparisons.
>
> Thanks,
>
> Mark H. Brooks Hedstrom


Helmert's Equation in the CRC gives the local value of g (in cm/s^2) as

g = 980.616 - 2.5928*cos(2*phi) + 0.0069*cos^2(2*phi) - 3.086x10^(-6)*H

where phi = latitude
and  H = elevation (in cm).

Use <http://www-nmd.usgs.gov/www/gnis/gnisform.html> to find phi and H.
One mus watch units carefully.


HTH,
Larry