Nothing spoils a good day of snow sampling like looking upwind to see a bulldozer lumbering by, broadcasting diesel-reeking soot all over the sample site. To maintain Summit's utility as a clean sampling area, the vast region to southeast of the TAWO observatory building is off-limits to human travel or to equipment operations. Under the prevailing winds, we breathe (and sample) air that's coming out of this 'clean air sector'. When the winds shift to the north, the weather displays literally turn red, and we curtail equipment operations to minimize contamination from exhaust. This clean air sector is marked with a line of bamboo flags that stretches to the horizon.
