Articles | Volume 10, issue 1
Atmos. Meas. Tech., 10, 167–178, 2017
Atmos. Meas. Tech., 10, 167–178, 2017

Research article 12 Jan 2017

Research article | 12 Jan 2017

Altitude registration of limb-scattered radiation

Leslie Moy1, Pawan K. Bhartia2, Glen Jaross2, Robert Loughman3, Natalya Kramarova1, Zhong Chen1, Ghassan Taha4, Grace Chen1, and Philippe Xu5 Leslie Moy et al.
  • 1Science Systems and Applications, Inc. (SSAI), 10210 Greenbelt Road, Suite 600, Lanham, Maryland 20706, USA
  • 2NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 3Hampton University, Hampton, Virginia, USA
  • 4GESTAR, Columbia, Maryland, USA
  • 5Science Applications International Corporation (SAIC), Lanham, Maryland, USA

Abstract. One of the largest constraints to the retrieval of accurate ozone profiles from UV backscatter limb sounding sensors is altitude registration. Two methods, the Rayleigh scattering attitude sensing (RSAS) and absolute radiance residual method (ARRM), are able to determine altitude registration to the accuracy necessary for long-term ozone monitoring. The methods compare model calculations of radiances to measured radiances and are independent of onboard tracking devices. RSAS determines absolute altitude errors, but, because the method is susceptible to aerosol interference, it is limited to latitudes and time periods with minimal aerosol contamination. ARRM, a new technique introduced in this paper, can be applied across all seasons and altitudes. However, it is only appropriate for relative altitude error estimates. The application of RSAS to Limb Profiler (LP) measurements from the Ozone Mapping and Profiler Suite (OMPS) on board the Suomi NPP (SNPP) satellite indicates tangent height (TH) errors greater than 1 km with an absolute accuracy of ±200 m. Results using ARRM indicate a ∼ 300 to 400 m intra-orbital TH change varying seasonally ±100 m, likely due to either errors in the spacecraft pointing or in the geopotential height (GPH) data that we use in our analysis. ARRM shows a change of ∼ 200 m over ∼ 5 years with a relative accuracy (a long-term accuracy) of ±100 m outside the polar regions.

Short summary
UV backscatter limb sounding sensors have difficulty determining altitude registration to the accuracy needed for long-term ozone monitoring. We describe two methods to achieve this by comparing radiance measurements to models. Wavelengths and altitudes chosen minimize errors from aerosol interference, calibration errors, and ozone assumptions. The techniques are inexpensive, more comprehensive than external sources of attitude information, and track drifts in our altitude to better than 100 m.