The ATLAS instrument is an advanced technology diode laser based absorption spectrometer designed specifically for stratospheric tracer studies. This technique was used in the acquisition of N2O tracer data sets on the Airborne Antarctic Ozone Experiment and the Airborne Arctic Stratospheric Expedition. These data sets have proved valuable for comparison with atmospheric models, as well as in assisting in the interpretation of the entire ensemble of chemical and meteorological data acquired on these two field studies. The N2O dynamical tracer data set analysis revealed several ramifications concerning the polar atmosphere: the N2O/NO(y) correlation, which is used as a tool to study denitrification in the polar vertex; the N2O Southern Hemisphere morphology, showing subsidence in the winter polar vortex; and the value of the N2O measurements in the interpretation of ClO, O3, and NO(y) measurements and of the derived dynamical tracer, potential vorticity. Field studies also led to improved characterization of the instrument and to improved accuracy

Loewenstein, Max

Podolske, James R.

Strahan, Susan E.

English

NASA Technical Reports Server

ATLAS:
N92-14511
Airborne Tunable Laser Absorption Spectrometer for
Stratospheric Trace Gas Measurements
Max Loewenstein and James R. Podolske
NASA Ames Research Center
Earth System Science Division
Moffett Field, Ca. 94035
Susan E. Strahan
San Jose State University
San Jose, Ca. 95192
The ATLAS instrument is an advanced technology diode laser-based
absorption spectrometer designed specifically for stratospheric
tracer studies. It was first deployed with the Stratosphere
Troposphere Exchange Project in 1987. The true fruition of this
technique has come with the highly successful acquisition of N20
tracer data sets on the Airborne Antarctic Ozone Experiment (AAOE,
1987) and the Airborne Arctic Stratospheric Expedition (AASE,
1989). These data sets have proved extremely valuable in
themselves for comparison with atmospheric models, as well as in
assisting in the interpretation of the entire ensemble of chemical and
meteorological data acquired on these two important field campaigns.
During the period covered by this report two major thrusts were
underway by the ATLAS research team: one was the analysis and
interpretation of the rich data sets acquired during the AAOE field
campaign in Punta Arenas, Chile in 1987, the other was preparation
for the AASE field campaign to Stavanger, Norway in December-
February 1989. The N20 dynamical tracer data set analysis revealed
several important ramifications concerning the polar atmosphere:
the N20/NOy correlation, which is now used as a tool to study
denitrification in the polar vortex; the N20 southern hemisphere
morphology, showing extensive subsidence in the winter polar
vortex; and the value of N20 measurements in the interpretation of
C10, 03 and NOy measurements and of the derived dynamical tracer,
potential vorticity. All of these implications of the N20 data sets are
explored in several papers appearing in the Journal of Geophysical
Research special issues on AAOE slated to appear late in 1989.
Various aspects of these N20 results were reported by ATLAS team
members at the Polar Ozone meeting, Snowmass, May 1988, the
Quadrennial Ozone Symposium, Goettingen, FRG, August 1988 and the
European Geophysical Society meeting, Paris, Sept. 1988.
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The field campaign known as AASE produced an additional large and
high quality N20 data set which has fully occupied the ATLAS team
with analysis and interpretation efforts since February 1989.
Several papers are now in preparation for a special Geophysical
Research Letters issue slated for early 1990 publication.
An intensive ATLAS instrument calibration effort during the first
half of 1989 led to an improved characterization of the instrument
under field conditions, and a well-based method for establishing the
accuracy of the field data from the AAOE and AASE campaigns. The
results are incorporated in a manuscript now being prepared for
publication.
References
Loewenstein, M., J. R. Podolske, K. R. Chan and S. E. Strahan, Nitrous
Oxide as a Dynamical Tracer in the 1987 Airborne Antarctic Ozone
Experiment, J. Geophys. Res. D, Special Issue on AAOE, in press.
Podolske, J. R., M. Loewenstein, S. E. Strahan and K. R. Chan,
Stratospheric Nitrous Oxide in the Southern Hemisphere, J. Geophys.
Res. D, Special Issue on AAOE, in press.
Strahan, S. E., M. Loewenstein, J, R. Podolske, W. L. Starr, M. H.
Proffitt, K. K. Kelly and K. R. Chan, Correlation of N20 and Ozone in the
Southern Polar Vortex During the Airborne Antarctic Ozone
Experiment, J. Geophys, Res. D, Special Issue on AAOE, in press.
7_
AIRBORNE MICROWAVE TEMPERATURE PROFILER INVESTIGATIONS
OF ATMOSPHERIC DYNAMICS RELATED TO OZONE DEPLETION
Research ObJectives
Bruce L. Gary
Jet Propulsion Laboratory
Pasadena, CA 91109
Airborne measurements are made of air temperature versus altitude using
microwave radiometric remote sensing techniques. The Microwave Temperature
Profiler, MTP, covers an altitude region that extends from approximately 2 km
below to 3 km above aircraft flight level. Three atmospheric science objectives
have been pursued using MTP data taken during flights into the Antarctic and
Arctic stratospheric polar vortices: 1) mountain waves in the polar strato-
sphere have been detected and characterized, 2) calculations of potential vor-
ticlty versus latitude have been made possible using the instrument's measure-
ments of air temperature lapse rate, and 3) a component of mesoscale vertical
oscillations of air parcels have been identified and characterized for use by
polar stratospheric cloud modelers needing realistic cooling rate simulations.
Progress and Results
Mountain waves were found to exist in the stratosphere over the Antarctica
Peninsula during the 1987 Airborne Antarctic Ozone Experiment (AAOE). Ver-
tical displacements as great as 600 meters (1200 meter peak-to-peak excur-
sions) were observed in the potential temperature surfaces. The mountain
waves were present approximately half the time during flight over the Penin-
sula and they were not found during flight over the open ocean. Wave
amplitude was found to increase with altitude in the region 17 to 22 km in
accordance with the predicted relation: Al=Ao/(PgPo) °'s. The unexpected
presence of mountain waves of such large amplitude in the stratosphere means
that airparcels may frequently experience brief cloud forming episodes, which
might influence ozone depletion through several possible routes.
Potential vorticitx calculations require knowledge of air temperature lapse
rate as well as horizontal wind shear. The MTP temperature profiles have
provided lapse rate information for the AAOE and 19B8/89 AASE (Airborne
Arctic Stratospheric Expedition) flights. Penetrations of the polar vortex
boundary show the expected changes in potential vorticity, which come entirely
from the wind field. Temperature field changes are not noticeable.
Potential temperature surfaces reveal information about vertical displace-
ments of air parcels. Cross-sections showing the altitudes of potential tem-
perature surfaces in a plane parallel to the wind direction can be used to in-
fer vertical velocities, which can be used to infer air parcel heating/cooling
rates. MTP data has been used to determine the power spectral density of
cooling rate versus frequency of oscillation. An apparently distinct "mesoscale
component" of temperature fluctuations appears in such a spectrum. This com-
ponent produces very large amplitudes of cooling that must be superimposed on
simulations of parcel temperature versus time-that are derived-from synoptic
scale weather data. When this is done cooling rates of 200 K/day are common,
and during passage through regions disturbed-by mountain waves parcels ex-
perience cooling rates as high as 2000 K/day. Brief as these cooling rates may
be, it is important to determine their impact on polar stratospheric cloud par-
ticle size distributions, since only large particles have fall speeds sufficient to
"denitrlfy" layers and thereby permit CIO chemical depletion of ozone.
Journal Publications
Gary, B. L., "Observational Results Using the Microwave Temperature Profiler
During the Airborne Antarctic Ozone Experiment," J. Geophys. Res., in press
Denning, R. F., S. L. Guldero, G. S. Parks, B. L. Gary, "Instrument Description of
the Airborne Microwave Temperature Profiler," J. Geophys. Res., In press
Hartmann, D. L., K. R. Chart, B. L. Gary, M. R. Schoeberl, P. A. Newman, R. L.
Martin, M. Loewenstein, J. R. Podolske, S. E. Strahan, "Potential Vorticity and
Mixing in the South Polar Vortex During Spring," J. Geophys. Res., In press
Proffitt, M. H., K. K. Kelly, J. A. Powell, M. R. Schoeberl, B. L. Gary_, M.
Loewensteln, J. R. Podolske, S. E. Strahan, K. R. Chan0 "Evidence for Diabatic
Cooling and Poleward Transport Within and Around the 1987 Antarctic Ozone
Hole," J. Geophys. Res., in press
75
STRATOSPttERE-TROPOSPBERE EXCHANGE DURING HIGH LATITUDE CYCLOGEN_SIS
AND LOWER ARCTIC STRATOSPHERE PROPERTIES
PI'S Melvyn A. Shapiro
NOAA/WPL
R/E/WP
Boulder, CO 80303
Russell C. Schne[l
CIRES, CB 449
University of Colorado
Boulder, CO 80309
CO-PI's Patrick J. Sheridan
Mike Douglas
CIRES, CB 449
Boulder, CO 80309
Nick Bond
JISAO/NOAA
University of Washington
Seattle, WA 98115
Objectives
There are two main objectives to the research:
I) The quantification of stratospheric-tropospheric exchange from NOAA
WP-3D measurements at higher latitudes and in the Arctic, and;
2) The measurement of aerosol properties in the lower Arctic
stratosphere as calibrations for concurrent SAGE-II measurements.
This is accomplished through analysis of data collected during 500 WP-3D
flight hours (1986-!989) in high latitude marine cyclogenesis systems and in
Arctic basin tropopause folding events.
Results to Date
I) Results from the tropopause folding portion of the research are best
summarized in graphical form. Figure I presents a vertical cross-section of
potential temperature (K) and along-front wind component (ms -I) for a NOAA WP-
3D study of a marine cold front at 40°N in the North Pacific Ocean, December
9, 1987. Figure 2 shows the ozone concentrations measured in the same frontal
structure. In this flight, the NOAA P-3 research aircraft documented the
descent of ozone laden stratospheric air down into the eastern Pacific marine
boundary layer. This stratospheric tropospheric exchange event occurred in
association with a jet stream-frontal zone tropopause folding event.
2) Aerosol light scattering data from 11 NOAA WP-3D research flights
into the Arctic spring tropopause and lower stratosphere have been compared to
28 corresponding SAGE-II extinction profiles. Results from this research show
that:
A. There is excellent agreement between the aircraft nephelometer
and the SAGE-II extinction measurements above 7 km in the
Arctic stratosphere;
B. The aerosol mininma at the Arctic tropopause, observed in
SAGE-II data, is also present in the airborne measurements.
76
Marine Cold Front
December 9, 1987
160 I _.u.i to,,,_,.l=., c.w,)--
o
. 60 70170 60 50A ..=,., ..=,._.
........_'"_'-\_ _-]- ,.,8 __-4--46
1 1 _._-'_ .,.-_ 40^_
// /f /// [" // _ #36
k: / / :: I
¢3r_
o
o 200 400 600 800 1000
Distance (km)
Publications
Figure i. Vertical cross-
section of potentlal
temperature (K), along front
wlnd components (ms-l),
selected wlnd barbs (kts)
and frontal boundaries
(heavy solid llnes) for a
North Pacific marine cold
front tropopause folding
event studied wlth the NOAA
WP-3D (aircraft track,
dotted llne).
Figure 2. Ozone
concentrations (ppb)
measured in the fold (Figure
I) illustrating the downward
Intrusion of elevated
concentration of ozone into
the marine boundary layer.
Barrle, L.A., J.W. Bottenhelm, R.C. Schnell, P.J. Crutzen, and R.A. Rasmussen,
Ozone destruction and photochemical reactions at polar sunrise in the
lower Arctic atmosphere, Nature, 334, 138-141, 1988.
Brldgman, R.A., R.C. Schnell, G.A. Herbert, B.A. Bodhalne, and S.J. Oltmans,
Meteorology and haze structure during AGASP-II: Part 2, Canadian Arctic
flights, April 13-16, 1986, J. Atmos. Chem. (Arctic Raze Issue), in
press, 1989.
Oltmans, S.J., W.E. Raatz, and W.D. Komhyr, On the transfer of stratospheric
ozone Into the troposphere near the North Pole, J. Atmos. Chem. (Arctic
Haze Issue), in press, 1989.
Oltmans, S.J., R.C. Schnell, P.J. Sheridan, R.E. Peterson, S.M. Li, J.W.
Winchester, P.P. Tans, W.T. Sturges, J.D. Kahl, and L.A. Battle, Seasonal
surface ozone and filterable bromine relationship in the hlgh Arctic,
Atmos. Envlron. (Arctic Haze Issue), in press, 1989.
77


ATLAS: Airborne Tunable Laser Absorption Spectrometer for stratospheric trace gas measurements

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