See the table below which I sourced from
http://www.physics.montana.edu/demonstrations/video/1_mechanics/demos/localgravitychart.htmlThere are a couple of anomalies, but it follows a straight line trend implying a difference of 0.5% between observed acceleration at equator and poles.
I don't know how the numbers were computed. If using a relative gravimeter, then perhaps Tom is right, although it defies belief that the smart people who devised these experiments missed something as obvious as atmospheric pressure. If an absolute gravimeter, then Tom is flat out wrong, and UA with it.
City, Acceleration, Abs lat
Quito, 9.7724, 0.1807
Singapore, 9.7814, 1.3521
Bogota, 9.7799, 4.711
Djakarta, 9.7814, 6.1805
Caracas, 9.7829, 10.4806
Lima, 9.7829, 12.0464
Manila, 9.7844, 14.5995
Guatemala City, 9.7844, 14.6349
Brasilia, 9.7889, 15.8267
La Paz, 9.7844, 16.4897
Mexico City, 9.7799, 19.4326
Port Louis, 9.7859, 20.1609
Hong Kong, 9.8099, 22.3964
Riyad, 9.7904, 24.7136
Taipei, 9.7904, 25.033
Johannesburg, 9.7919, 26.2041
Manamah, 9.7904, 26.2285
Kuwait, 9.7919, 29.3117
Panama City, 9.7814, 30.1588
Dallas, 9.7949, 32.7767
Baghdad, 9.7964, 33.3152
Santiago, 9.7979, 33.4489
Atlanta, 9.7964, 33.749
Sydney, 9.7979, 33.8688
Beirut, 9.7964, 33.8938
Rabat, 9.7964, 33.9716
Los Angeles, 9.7979, 34.0522
Buenos Aires, 9.7979, 34.6037
Montevideo, 9.7964, 34.9011
Mishima, 9.7979, 35.1184
Nicosia, 9.7979, 35.1856
Tunis, 9.7799, 36.8065
San Jose, 9.7829, 37.3382
Seoul, 9.7994, 37.5665
San Francisco, 9.7994, 37.7749
Athens, 9.8009, 37.9838
Lisbon, 9.8039, 38.7223
Ankara, 9.8024, 39.9334
Philadelphia, 9.8024, 39.9526
Madrid, 9.8024, 40.4168
New York, 9.8024, 40.7128
Wellington, 9.8039, 41.2865
Chicago, 9.8024, 41.8781
Detroit, 9.8039, 42.3314
Boston, 9.8039, 42.3601
Toronto, 9.8054, 43.6532
Bucharest, 9.8054, 44.4268
Ottawa, 9.8069, 45.4215
Montreal, 9.8069, 45.5017
Bern, 9.8084, 46.948
Budapest, 9.8069, 47.4979
Vienna, 9.8099, 48.2082
Vancouver, 9.8099, 49.2827
Prague, 9.8114, 50.0755
Brussels, 9.8114, 50.8503
Dusseldorf, 9.8129, 51.2277
London, 9.8144, 51.5074
Swider, 9.8159, 51.8986
Amsterdam, 9.8129, 52.368
Copenhagen, 9.8159, 55.6761
Stockholm, 9.8189, 59.3293
Oslo, 9.8189, 59.911491
Helsinki, 9.8189, 60.1699
Anchorage, 9.8189, 61.2181