Tropospheric OH is buffered and thus relative stable in either a regional scale or global scale. Snow photochemistry in the high latitude amplifies the OH photochemical production in the low atmosphere following cross-boundary transport of snow impurities. As a result, the Antarctic pole OH and the Arctic pole OH resonate with emission inventory decline in the Europe since 1960s. Although the whole picture of snow photochemistry is not totally clear, intensive UV with high solar zenith angle and cross-boundary transport and deposition of HNO₃/nitrate is known to favor a maximizing snow NO_x emission flux and efficiency in the Mt. Everest. Consequently, the highest OH and highest growth slope of OH are revealed for the Mt. Everest with a nearly-explicit chemical model of MCM. Unlike relatively slow vertical mixing in the shallow boundary layer of the Antarctic and the Arctic, the Mt. Everest features the most intensive occurring of the deepest convection which effectively deliveries surface airmasses into the global circulation system. The global impacts on the oxidative capacity of the atmosphere is thus likely and needs further evaluation.
 

OH,NOx,snow photochemistry