HR: 0830h
AN: A21C-0974    [PDF]
TI: HNO$_3$ From MLS: Building on the UARS Legacy With Aura Measurements
AU: * Santee, M L
EM: mls@mls.jpl.nasa.gov
AF: Jet Propulsion Laboratory, Mail Stop 183-701 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Manney, G L
EM: manney@mls.jpl.nasa.gov
AF: Jet Propulsion Laboratory, Mail Stop 183-701 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Manney, G L
EM: manney@mls.jpl.nasa.gov
AF: New Mexico Highlands University, Department of Natural Sciences, Las Vegas, NM 87701 United States
AU: Read, W G
EM: bill@mls.jpl.nasa.gov
AF: Jet Propulsion Laboratory, Mail Stop 183-701 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Livesey, N J
EM: livesey@mls.jpl.nasa.gov
AF: Jet Propulsion Laboratory, Mail Stop 183-701 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Filipiak, M J
EM: mjf@met.ed.ac.uk
AF: The University of Edinburgh, Department of Meteorology, Edinburgh, EH9 3JZ United Kingdom
AU: Waters, J W
EM: joe@mls.jpl.nasa.gov
AF: Jet Propulsion Laboratory, Mail Stop 183-701 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AB: The Microwave Limb Sounder (MLS) onboard the Upper Atmosphere Research Satellite (UARS) measured the global distribution of stratospheric HNO$_3$ over annual cycles for much of the 1990s, albeit with reduced sampling frequency in the latter half of the decade. The UARS MLS HNO$_3$ dataset, unique in its scope, has previously been studied to explore the seasonal, interhemispheric, and interannual variations in the distribution of HNO$_3$. This work, however, suffered from a number of limitations: It was confined to a single level in the lower stratosphere (465\,K potential temperature), it was based on version~4 MLS data, and it relied heavily on zonal-mean comparisons of the evolution of HNO$_3$ in the northern and southern hemispheres. Here we update and significantly expand the previous work by examining the distribution of HNO$_3$ throughout the lower and middle stratosphere from 420 to 960\,K. We use version~6 MLS HNO$_3$ data, which, in addition to having much better precision, a larger vertical range, and better definition of the HNO$_3$ profile, have also been corrected to account for the neglect of some excited vibrational state lines that caused the version~4 (and version~5) retrievals to substantially overestimate HNO$_3$ peak values. In addition, we calculate averages over equivalent latitude, which are more representative of vortex behavior than zonal means, especially in the Arctic. This work provides a comprehensive picture of the behavior of stratospheric HNO$_3$ during the UARS timeframe and establishes an important baseline for upcoming measurements from the EOS Aura mission, which will include a second-generation MLS experiment. The capability of EOS MLS is greatly enhanced over that of UARS MLS. We review the anticipated improvements in the EOS MLS HNO$_3$ measurements (e.g., better spatial and temporal coverage, better horizontal and vertical resolution, larger vertical range), show some results from retrieval simulations, and discuss a few specific polar process studies that are planned with the EOS MLS HNO$_3$ data.
UR: http://mls.jpl.nasa.gov
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting