DORIS Observations from Iridium for Atmospheric Science

Study of the upper and lower atmosphere has advanced to the point where a compelling need has emerged for global real-time specification of the most important observations as inputs to climate and other high-resolution assimilative models. For the ionosphere, plasmasphere and magnetosphere this is the local free electron density (ED); for the troposphere it is the local water vapor content (WVC). Currently, data describes only the synoptic (few to tens of degrees) features of the ionosphere, but the science requires mesoscale (tens to hundreds of km) description. We describe a proposal, made to both the GEOScan Earth geoscience collaboration and to the U.S. Air Force, for a DORIS receiver to be flown on the Iridium-NEXT constellation that would provide precise, real-time global specifications of ionosphere 3D electron density profile (EDP) and of troposphere WVC, as well as ionospheric scintillation maps at two length scales. We emphasize the ionospheric feature sizes that could be resolved - 100 km scale or less horizontally - and how the data sets obtained could help illuminate the transition from persistent to turbulent structures. Iridium-NEXT is a constellation of 66 satellites in six polar orbit planes, to be deployed from 2015-2017. We describe how the DORIS frequency lever arm is superior to that of GPS for probing the ionosphere, and how DORIS data is currently being used to generate WVC data sets of comparable precision to GPS and VLBI data. Instrument data would be persistent, global and real-time, and made publicly available in near-real-time.