All variations in atmospheric pressure can cause disproportionate effects on the brew quality. Even the difference between the base of a sand dune and the top. Don't even get me started on pressure changes caused by weather. 980mbar vs 1020? It's night and day difference, seriously. Really important to quantify all variables and adjust accordingly.
I hope you use a calibrated scale to weigh your beans (before and after grinding) when you are camping.
