This report is a continuation of the analysis of data from past flights, exploring issues such as radical partitioning, stratospheric transport, and the ozone budget

Chance, Kelly V.

Traub, Wesley A.

English

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MEASUREMENT OF HO2 AND OTHER TRACE GASES IN THE STRATOSPHERE
USING A HIGH RESOLUTION FAR-INFRARED SPECTROMETER
NASA GRANT NSG 5175
Final Report
For the period t April 1998 to 31 March 1999
Principal Investigators
Wesley A. Traub
Kelly V. Chance
June 1999
Prepared for
National Aeronautics and Space Administration
Greenbelt, Maryland 20771
Smithsonian Institution
Astrophysical Observatory
Cambridge, Massachusetts 02138
The Smithsonian Astrophysical Observatory
is a member of the
Harvard-Smithsonian Center for Astrophsysics
The NASA Technical officer for this grant is Dr. John Burris, Code 916, Atmospheric
Experiments Branch, Goddard Space Flight Center, Greenbelt, Maryland 20771
https://ntrs.nasa.gov/search.jsp?R=19990071187 2020-06-15T21:51:03+00:00Z

Final Report
NASA Grant NSG-5175
Measurement of HO 2 and Other Trace Gases in the Stratosphere Using a High
Resolution Far-Infrared Spectrometer
1. Personnel Working Under this Grant During this Reporting Period
Dr. Wesley A. Traub (Principal Investigator)
Dr. Kelly V. Chance (Principal Investigator)
Dr. David G. Johnson (Co-Investigator)
Dr. Kenneth W. Jucks (Co-Investigator)
Dr. Ross J. Salawitch (Co-Investigator)
2. Status Summary
This report covers the time period 1 April 1998 to 31 March 1999. During this period we con-
tinued analyzing data from past flights, exploring issues such as radical partitioning, stratospheric
transport, and the ozone budget.
3. Instrument and Software Development
We have completed an on-board data recorder, partially funded by the Smithsonian Institution
(SI), so that we can reduce our reliance on high-quality telemetry during balloon flights. The system
holds almost 150 hours of data and also enables control of the instrument over the Internet, allowing
remote ground-based observing.
We have also completed a gas cell for lab measurements, partially funded by SI, so that we
can check the accuracy of spectroscopic parameters used in our retrievals.
We are making excellent progress towards porting our data reduction software from the Open-
VMS operating system to Unix. Once the migration is complete we will finally retire our obsolete
Vaxcluster and perform future data reduction and analysis tasks on modern Sun Ultra 5 worksta-
tions.
4. Data Interpretation
Understanding the stratospheric ozone budget requires accurate modeling of the HO:, NOv,
and Cly families. FIRS-2 has the unique ability to make simultaneous measurements of most
members of these chemical families throughout the middle stratosphere, during both day and,
for those species which do not disappear, at night. During this reporting period we continued our
studies of chemical partitioning, with one paper on HO_ appearing in print; a paper on HNO3/NOy
has been accepted by JGR, and a paper on on HC1/CI_ has been submitted.
We find that our measurements of HC1/Cly for the period 1989-1997 are in good agreement
with model calculations, in contrast with the conclusions of recent studies of in-situ measurements,
and that much of the variability we see in this ratio is driven by changes in [CH4]/[O3] 2. Reactions
on sulfate aerosols are not important except under conditions of high aerosol surface area density
and unusually low temperatures.
We conclude from our studies of HNO3/NO_ that recently recommended changes in the rates
of the OH + NO2 and OH + HNO3 reactions produce improved agreement between photochemical
modelcalculationsandstratosphericobservations,but significantdiscrepanciesremain,especially
in the middleandupperstratosphere.
Wehavebeenexaminingthe isotopiccompositionof stratosphericozoneusingFIRS-2mea-
surementsof symmetricand asymmetric4903 and S°o3. We find that our measurementsof the
enhancementin heavyisotopesarein excellentagreementbothwith recentlypublishedresultsand
with calculationsbasedon measuredrateconstantsfor isotopicvariantsof the Chapmanreactions.
FIRS-2measurementsmayshednewlight on themechanismproducingenhancementsby providing
the first high-precisionmeasurementsof both symmetricand asymmetricforms.
Understandingthe effectof anthropogenicactivities on stratosphericozonerequiresunder-
standingboth photochemistryand transport, and to this end we havecontinuedour work on
transport issues.At presentweareexploringtroposphere-stratospheretransportandstratospheric
agespectra.
Watervaporprovidesa uniquetracerof troposphere-stratospheretransport becausethewater
vapor mixing ratio is determinedby the lowesttemperatureencounteredby an air parcel. The
minimum temperaturetypically occursat the tropopause,and it haslong beennoted that the
tropicsis the onlyregionwith lowenoughtropopausetemperaturesto explaintheextremedryness
of the stratosphere.Because5D and 51So are also affected by condensation, measurements of
the isotopic composition of water vapor can further constrain models of stratospheric dehydration
and transport. In work still in progress, we find that FIRS-2 measurements of 5D and 5180 are
best explained by allowing mixing between roughly 100 and 200 mb, which suggests that the mass
flux across the tropical tropopause is not dominated by direct injection of convected air into the
stratosphere but by slow heating and uplift in the uppermost tropical troposphere, as suggested by
some current transport models.
In a paper now in press at JGR, we use our measurements of H20, together with measurements
made by the JPL MkIV interferometer, to correct for systematic biases in the SAGE II and HALOE
instruments. We then combine the data sets to produce a global record of stratospheric H20
covering 1986-present. By comparing the time variation in H_O + 2(CH4) at different altitudes and
latitudes with the record at the tropical tropopause, we are able to estimate the age spectrum of
stratospheric air as a function of altitude and latitude. While the resulting estimates have relatively
low precision, we believe that the technique shows great promise and that estimates will improve
as the satellite record continues to grow in time.
In collaboration with colleagues at NIES in Japan we have continued our work on calibrating
and validating data from the ILAS sensor on board the ADEOS satellite. We have compared FIRS-2
observations from 30 April 1997 with ILAS version 4.0 data, and believe the results confirm the drift
in the ILAS slit function proposed by ILAS project scientists. We presented these comparisons,
along with scientific interpretations of both FIRS-2 and ILAS data, at the ILAS science team
meeting in Nara, Japan during March 1999.
5. Publications and Presentations
Jucks, K. W., D. G. Johnson, K. V. Chance, W. A. Traub, J. J. Margitan, G. B. Osterman, R. J.
Salawitch, and Y. Sasano, Observations of of OH, HO2, H20, and 03 in the upper stratosphere:
Implications for HO_ photochemistry, Geophys. Res. Lett., 25, 3935-3938, 1998.
Johnson, D. G., K. W. Jucks, W. A. Traub, K. V. Chance, G. C. Toon, J. M. Russell III, and M.
P. McCormick, Stratospheric age spectra derived from observations of water vapor and methane,
J. Geophys. Res., in press, 1999.
Jucks, K. W., D. G. Johnson, K. V. Chance, W. A. Traub, and R. J. Salawitch, Nitric acid in the
middle atmosphere as a function of altitude and aerosol loading, J. Geophys. Res., in press, 1999.
3
Jucks,K. W., D. G. Johnson,W. A. Traub,K. V. Chance,G. C. Toon,J.-F. Blavier,B. Sen,G. B.
Osterman,andR. J. Salawitch,Mid-latitude HC1in the lowerstratosphere:Balloonobservations
beforeduringandafter Pinatubo, J. Geophys. Res., submitted, 1999.
Johnson, D. G., K. W. Jucks, W. A. Traub, and K. V. Chance, Isotopic composition of stratospheric
ozone, in preparation, 1999.
Jucks, K. W., D. G. Johnson, W. A. Traub, K. V. Chance, R. A. Stachnik, G. C. Toon, G.
B. Osterman, and R. J. Salawitch, Photochemical Partitioning of NO×/NOy and Clx/Cly in the
Middle and Upper Stratosphere in the Spring at High Latitude, presented at the Atmospheric
Effects of Aviation meeting, Virginia Beach, April, 1998.
Jucks, K. W., D. G. Johnson, W. A. Traub, K. V. Chance, G. C. Toon, R. A. Stachnik, R. J.
Salawitch, and G. B. Osterman, Photochemical partitioning of HO×, Cly, and NOy in the middle
and upper stratosphere, poster presented at the meeting of the American Geophysical Union,
Boston, May 1998, and the OMS/POLARIS/STRAT science team meeting, Snowmass, June 1998.
Johnson, D. G., K. W. Jucks, W. A. Traub, K. V. Chance, FIRS-2 observations of H2160, H21SO,
and HDO: Constraints on the stratospheric dehydration mechanism, presented at the meeting of
the American Geophysical Union, Boston, May 1998.
Johnson, D. G., K. W. Jucks, W. A. Traub, K. V. Chance, FIRS-2 observations of the abundance
and isotopic composition of H20 in the stratosphere: Implications for transport, poster presented
at OMS/POLARIS/STRAT science team meeting, Snowmass, June 1998.
Johnson, D. G., K. W. Jucks, W. A. Traub, K. V. Chance, FIRS-2 measurements of the isotopic
composition of water vapor and ozone, presented at the meeting of the American Geophysical
Union, San Francisco, December, 1998.
Jucks, K. W., D. G. Johnson, W. A. Traub, K. V. Chance, R. J. Salawitch, and G. B. Osterman,
Photochemical Partitioning of NOy and HO_ in the Middle and Upper Stratosphere at Mid and High
Latitudes,presented at the meeting of the American Geophysical Union, San Francisco, December,
1998.



Measurement of HO2 and Other Trace Gases in the Stratosphere using a High Resolution Far-Infrared Spectrometer

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