I've been researching ocean acidification, and the way that ocean pH is typically measured is by using sensors placed throughout all of the oceans. This is costly and time-consuming, and being able to measure ocean pH from space would be much more efficient as a global map could be created in a relatively short time and updated regularly.
However, when I researched pH measurement techniques, they all involve an instrument physically touching a solution, which would obviously not be possible from space. Ocean pH maps that have been created using satellite data measure pH indirectly by measuring ocean salinity, temperature, and other conditions, and they point out areas where it is "likely" that pH levels are low enough to harm ocean life. Is is possible to directly measure pH from a large distance? Would it be necessary to do so, that is to say, is measuring ocean pH levels indirectly accurate enough for environmental monitoring?