The Stratospheric Aerosol and Gas Experiment (SAGE III) on the International Space Station (ISS) Mission

Abstract

The Stratospheric Aerosol and Gas Experiment III on the International Space Station (SAGE III/ISS) mission will provide the science community with high-vertical resolution and nearly global observations of ozone, aerosols, water vapor, nitrogen dioxide, and other trace gas species in the stratosphere and upper-troposphere. SAGE III/ISS measurements will extend the long-term Stratospheric Aerosol Measurement (SAM) and SAGE data record begun in the 1970s. The multi-decadal SAGE ozone and aerosol data sets have undergone intense scrutiny and are considered the international standard for accuracy and stability. SAGE data have been used to monitor the effectiveness of the Montreal Protocol. Key objectives of the mission are to assess the state of the recovery in the distribution of ozone, to re-establish the aerosol measurements needed by both climate and ozone models, and to gain further insight into key processes contributing to ozone and aerosol variability. The space station mid-inclination orbit allows for a large range in latitude sampling and nearly continuous communications with payloads.The SAGE III instrument is the fifth in a series of instruments developed for monitoring atmospheric constituents with high vertical resolution. The SAGE III instrument is a moderate resolution spectrometer covering wavelengths from 290 nm to 1550 nm. Science data is collected in solar occultation mode, lunar occultation mode, and limb scatter measurement mode.A SpaceX Falcon 9 launch vehicle will provide access to space. Mounted in the unpressurized section of the Dragon trunk, SAGE III will be robotically removed from the Dragon and installed on the space station. SAGE III/ISS will be mounted to the ExPRESS Logistics Carrier-4 (ELC-4) location on the starboard side of the station. To facilitate a nadir view from this location, a Nadir Viewing Platform (NVP) payload was developed which mounts between the carrier and the SAGE III Instrument Payload (IP).

The Ozone Mapping and Profiler Suite (OMPS) Limb Profiler (LP) Version 1 aerosol extinction retrieval algorithm: theoretical basis

“…The stratospheric aerosol layer is enhanced by volcanic eruptions that inject SO 2 into the stratosphere, creating a layer of H 2 SO 4 droplets that spreads quickly in the horizontal directions (and much more slowly in the vertical direction), slowly dissipating over a period from months to several years. Volcanic eruptions also may inject ash particles directly into the stratosphere, and mineral dust from the ablation of meteors also can augment the stratospheric aerosol layer (Cziczo et al, 2001). Several competing influences therefore affect the stratospheric aerosol layer, including volcanic activity, stratosphere-troposphere exchange, stratospheric transport processes, gas-to-droplet conversion rates, and particle sedimentation.…”

Intercomparison of Pandora stratospheric NO<sub>2</sub> slant column product with the NDACC-certified M07 spectrometer in Lauder, New Zealand

“…The Stratospheric Aerosol and Gas Experiment (SAGE) missions have provided a legacy of high-quality solar occultation measurements for vertically profiling stratospheric O 3 and ultraviolet-visible-near-infrared aerosol extinction coefficients from the upper troposphere into the mesosphere for more than 3 decades McCormick, 1979, 1986;Damadeo et al, 2013;Cisewski et al, 2014). These observations have formed a crucial component for understanding ozone trends and the influence of stratospheric chemistry and aerosol on ozone mixing ratios and climate.…”

“…To this end, the standard data products for this mission are aerosol extinction coefficients, aerosol optical depth, O 3 , H 2 O, and NO 2 mixing ratios. For an overview of the instrument and products see Cisewski et al (2014).…”

The Ozone Mapping and Profiler Suite (OMPS) Limb Profiler (LP) Version 1 Aerosol Extinction Retrieval Algorithm: Theoretical Basis

“…This was updated in to calculate the MS source functions at multiple solar zenith angles along the LOS, increasing the accuracy of the MS radiances. Total radiance errors that had reached 10% in the Loughman et al (2004) comparisons decline to 1 − 3% in the updated comparisons 25 presented by .…”