Evaluation of MLS mesospheric geopotential height profiles and improved altitude registration of the OMPS Limb Profiler measurements

Monday, 15 December 2014
Leslie Moy1, Pawan K Bhartia2, Zhong Chen1, Matthew T DeLand3, Glen R Jaross2, Thomas J Kelly1, Natalya A Kramarova4, Robert Paul Loughman5, Ghassan Taha6 and Philippe Xu2, (1)Science Systems and Applications, Inc., Lanham, MD, United States, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)Sci Systems & Applications Inc, Lanham, MD, United States, (4)NASA GSFC, Greenbelt, MD, United States, (5)Ctr Atmospheric Sciences, Hampton, VA, United States, (6)Universities Space Research Association Greenbelt, Greenbelt, MD, United States
We have developed a method of evaluating the mesospheric geopotential height (GPH) profiles provided by Aura MLS using Suomi OMPS Limb Profiler (LP) measurements at 350 nm. Our results indicate that the error in MLS GPH profiles increases with altitude. We compare our results with the errors calculated by the MLS team based on internal error analysis. Their error estimates have never been independently verified. This evaluation has, in turn, helped us to develop a more accurate altitude registration method of the OMPS LP measurements, with an estimated accuracy of +/- 100 m. Prior to launch of the Suomi NPP spacecraft in October 2011, there were concerns that flexing of its structure could cause large pitch angle errors at the OMPS instrument location, leading to altitude registration errors. While Suomi NPP contains an accurate star tracker, it is located near the VIIRS instrument on the opposite end of the spacecraft. Our results indicate that the variation in Suomi NPP pitch angle along the orbit at the location of the OMPS LP instrument is less than 20 arc-second (corresponding to 300 m in altitude registration at the limb). We also find that the variation of the pitch error along the orbit is highly repeatable from day to day, and has not varied significantly over the past 3 years since launch. Finally, our results confirm and improve upon previous estimates of ~2 arc-minute pitch error (2 km at the limb) in mounting the OMPS LP instrument on the NPP spacecraft.