Validation of the Aura Microwave Limb Sounder HNOmeasurements

Authors

M L. Santee, California Institute for Human Science
A Lambert, California Institute of Technology
W G. Read, California Institute of Technology
N J. Livesey, California Institute of Technology
R E. Cofield, California Institute of Technology
D T. Cuddy, California Institute of Technology
W H. Daffer, California Institute of Technology
B J. Drouin, California Institute of Technology
L Froidevaux, California Institute of Technology
R A. Fuller, California Institute of Technology
R F. Jarnot, California Institute of Technology
B W. Knosp, California Institute of Technology
G L. Manney, California Institute of Technology
V S. Perun, California Institute of Technology
W V. Snyder, California Institute of Technology
P C. Stek, California Institute of Technology
R P. Thurstans, California Institute of Technology
P A. Wagner, California Institute of Technology
J W. Waters, California Institute of Technology
G Muscari, Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
R L. de Zafra, State University of New York at Stony Brook
Jack E. Dibb, University of New HampshireFollow
D W. Fahey, NOAA
P J. Popp, NOAA
T P. Marcy, NOAA
K W. Jucks, Harvard-Smithsonian Center for Astrophysics
G C. Toon, California Institute of Technology
R A. Stachnik, California Institute of Technology
P F. Bernath, University of Waterloo
C D. Boone, University of Waterloo
K A. Walker, University of Waterloo
J Urban, Chalmers University of Technology
D Murtagh, Chalmers University of Technology

Abstract

We assess the quality of the version 2.2 (v2.2) HNO₃ measurements from the Microwave Limb Sounder (MLS) on the Earth Observing System Aura satellite. The MLS HNO₃ product has been greatly improved over that in the previous version (v1.5), with smoother profiles, much more realistic behavior at the lowest retrieval levels, and correction of a high bias caused by an error in one of the spectroscopy files used in v1.5 processing. The v2.2 HNO₃ data are scientifically useful over the range 215 to 3.2 hPa, with single-profile precision of ∼0.7 ppbv throughout. Vertical resolution is 3–4 km in the upper troposphere and lower stratosphere, degrading to ∼5 km in the middle and upper stratosphere. The impact of various sources of systematic uncertainty has been quantified through a comprehensive set of retrieval simulations. In aggregate, systematic uncertainties are estimated to induce in the v2.2 HNO₃ measurements biases that vary with altitude between ±0.5 and ±2 ppbv and multiplicative errors of ±5–15% throughout the stratosphere, rising to ∼±30% at 215 hPa. Consistent with this uncertainty analysis, comparisons with correlative data sets show that relative to HNO₃ measurements from ground-based, balloon-borne, and satellite instruments operating in both the infrared and microwave regions of the spectrum, MLS v2.2 HNO₃ mixing ratios are uniformly low by 10–30% throughout most of the stratosphere. Comparisons with in situ measurements made from the DC-8 and WB-57 aircraft in the upper troposphere and lowermost stratosphere indicate that the MLS HNO₃ values are low in this region as well, but are useful for scientific studies (with appropriate averaging).

Department

Earth Sciences, Earth Systems Research Center

Publication Date

12-27-2007

Journal Title

Journal of Geophysical Research

Publisher

Wiley

Digital Object Identifier (DOI)

10.1029/2007JD008721

Document Type

Article

Recommended Citation

Santee, M. L., et al. (2007), Validation of the Aura Microwave Limb Sounder HNO3 measurements, J. Geophys. Res., 112, D24S40, doi:10.1029/2007JD008721.

Rights

Copyright 2007 by the American Geophysical Union.