Why did revelle and keeling choose the middle of the pacific for these measurements?

Answer 1

Keeling recognized that early measurements in England and France had been influenced locally by continental vegetation, and he found the same problem with his own early measurements along the west coast of the U.S.. Coastal weather systems were entraining the continental signal. So, with the goal of getting to a large volume of atmosphere, well-mixed, without a large amount of CO2 "signal" from land vegetation, he decided to measure in the middle of the Pacific, using shipboard measurements and island-based stations (Christmas and Fanning islands, and Hawaii). Atop Mauna Loa the mountain pokes through the "boundary layer", giving good sampling of well-mixed air over very large expanse. (When sampling is not upwind of the volcano, the monitor is shut off).

[For my Master's Thesis research with Keeling, I compared shipboard sampling in the Pacific against the island stations, to determine the effect of stochastic weather events. --Jusin Lancaster, Ph.D., 1990, Scripps Inst. Oceanography]

Answer 2

They had a specific target to focus the latest investigative equipment upon.

Answer 3

for them to be accurate