During the spring 2008 phase of the NASA ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) field campaign, measurements of BrO, O3, and related species were obtained in the Arctic region from in situ aircraft instruments, ground-based spectrometers, and satellite sensors. The field measurements were designed to reveal details about the spring-time phenomena of enhanced Arctic BrO known as the "bromine explosion". Surprisingly, the regions of enhanced BrO and depleted tropospheric ozone measured by instruments aboard the NASA DC-8 aircraft were typically not co-located with OMI satellite measurements of elevated total column BrO. We show that many of the regions of enhanced column BrO measured by OMI can be explained by transport of stratospheric BrO to low altitude, provided there is a large burden, ~10 ppt, of stratospheric bromine supplied by very short lived halocarbon species. This burden of bromine is typically not represented in global models, yet has important implication for the photochemistry of ozone and other compounds.