Validation of MOPITT carbon monoxide and methane measurements using remote sensing by IR solar spectroscopy of moderate resolution combined with in-situ measurements.
(Approved by NASA, September 15, 1997)
CLICK HERE FOR THE MOST RECENT ACTIVITY REPORT
Principal Investigator: Dr. Leonid N.Yurganov
Coinvestigator: Dr. Eugeny I. Grechko.
NRA-97-MTPE-03,
Letter of intent #307.
Type of proposal: 2
ABSTRACT
The aim of MOPITT correlative gas spectrometer is to determine vertical
profiles of CO and total column CH4 abundance from space. Ground-based
solar IR spectroscopy is able to supply information not only on total column
amounts of gases, but also on their vertical distribution. The latter goal
can be achieved using either spectroscopy of high resolution (alone) or
spectroscopy of moderate resolution in combination with boundary layer
data. Grating spectrometers of moderate resolution (0.2 cm-1)
have been being used for a long time for total column CO measurements in
Russia. Routine CO and CH4 measurements are under way now at
two sites in Russia (Zvenigorod and Kislovosk). Now a Russian spectrometer
is moved for a comparison and intercalibration to Canada. We propose to
compare the CO and CH4 total columns with those obtained by
FTIR high-resolution spectrometer, installed at the Egbert station (AES
of Canada). Grating spectrometer will be used in field validation campaigns
during the EOS flight in combination with concurrent surface in-situ measurements
and/or aircraft sampling. The intercalibration against the FTIR would give
us (I) assurance of validity of the grating spectrometer data, and (II)
a possibility to use Russian spectroscopic data, obtained by the same technique,
for the validation of MOPITT. Both Canadian and Russian activities will
be funded by national programs. We do not solicit funding from NASA.
OBJECTIVE
Main goal of this proposal is a validation of MOPITT CO and methane
measurements using solar spectroscopy of moderate resolution in three sites:
two sites in Russia and one site in Canada.
BACKGROUND
Atmospheric carbon monoxide. CO long-term trend
Human activity is responsible for about half of the carbon monoxide
(CO)input in the Northern Hemisphere (NH). In addition several natural
processes, most important of which are forest fires and oxidation of methane
and other hydrocarbons, contribute to the CO cycle. A reaction between
CO and OH is the major sink for both CO and OH ( Mueller and Brasseur,
1995). Radical OH in turn is the main oxidizing agent in the background
troposphere, representing, for example, more than 80 % of the total sink
for atmospheric methane, a very important greenhouse gas. Radical OH is
a product of photochemical reactions in the troposphere; OH depends on
UV radiation flux and the concentrations of ozone, NOx, water vapor, CO
and other trace gases and radicals ( Mueller and Brasseur, 1995).
A trend of CO, therefore, is a critically important factor, which determines
tropospheric hydroxyl concentration in the global atmosphere. From the
other hand, CO concentration itself depends on OH concentration. A first
rough estimate of CO long-term trend for background NH air was obtained
by Dianov-Klokov and Yurganov (1981) from a comparison of total column
spectroscopic measurements in Zvenigorod, near Moscow in 1970-1976 to those
conducted by Shaw (1958) in Columbus, Ohio, in 1952-1953. A spectroscopic
technique was used also by Zander et al. (1989) at the high altitude station
Jungfraujoch, Switzerland; their estimate was 0.85 ± 0.20 %/year. Dvoryashina
et al. (1984) estimated the trend in Zvenigorod between 1970 and 1982 to
be 1.4 and 1.7 %/year for summer and winter, respectively. A stabilisation
or even a decrease of CO was reported for the period after 1983-1987. No
increase was observed between 1983 and 1993 in Zvenigorod (-0.08 ± 0.5
%/year, according to Yurganov et al. (1995). Flask samples of surface air
revealed even a decrease in CO concentration. ( Khalil and Rasmussen, 1994)
found rates of -1.3 ppbv/year in the NH and -2.3 ppbv/year in the Southern
Hemisphere (SH) between 1987 and 1992. Novelli et al.(1994) reported rates
of -7.7 and -3.7 ppbv/year for NH and SH, respectively, for a shorter period
between 1990 and 1993.
Several hypotheses have been proposed to explain this behaviour of carbon
monoxide. A decline of the rate of man-induced CO emission after 1983 has
been postulated ( Khalil and Rasmussen, 1994; Novelli et al., 1994). An
increase in UV flux due to stratospheric ozone depletion after 1982 resulted
in an increase of OH, which, in turn, reduced the rate of CO and methane
growths. OH decrease due to a screening of the troposphere from solar UV
radiation by the Pinatubo volcanic sulfate aerosol was proposed by Dlugokencky
et al. (1996) to explain CO variations between 1990 and 1993.
In our recent paper (Yurganov et al., 1997a) the updated time series
of Zvenigorod CO measurements was presented and analysed. It was concluded
that for the whole period between late 1940s and the present time the CO
trend was close to linear with a rate appr. 1% per year. There is little
or no indication of CO slowing down. But CO total column amount depends
significantly on UV radiation, which keeps under control the hydroxyl source
(ozone dissociation by UV and the reaction of the excited oxygen atom with
water vapor). The intensity of UV strongly depends on stratospheric composition:
both submicron aerosol and ozone concentrations. It was shown that CO over
Zvenigorod underwent an influence of changes in the stratospheric composition,
caused by both El-Chichon and Pinatubo volcanoes. Intense forest and peat
fires around Moscow in 1972 influenced total column CO as well. These data
will be quite valuable in the proposed activity on MOPITT validation.
It was found that in many cases even in the Northern Hemisphere CO is
uniformly distributed in the troposphere. Moreover, very many events of
lifted polluted atmospheric layers used to observe. The origin of enhanced
CO in these layers was questionable, but two main sources were considered
as the most probable: urban emissions and products of biomass burning.
Much more detailed and abundant experimental investigations, however,
are necessary. In this concern a combination of spectroscopy with regular
surface sampling (like that, performed by Novelli et al., 1994) looks very
promising. Total column amount of the gas can be compared to its surface
concentration. Vertical CO distribution can be chosen to match total column
and the surface concentration.
Our measurements in Alaska (Yurganov et al., 1997b) demonstrated advantages
of this approach for the first time. It should be noted, that the Arctic
represents a relatively convenient environment for a validation of space-borne
instruments from the surface. This is connected, first of all, with a lack
of local sources of CO emissions. Remote transport of man-made pollutants,
however, plays a very important role, especially in winter-spring. Because
of long travelling paths a high degree of horizontal mixing in the Arctic
is achieved. However, we found, that vertical CO distribution over Alaska
was far from a uniform one. As a rule, in March - early April CO appeared
to diminish with altitude with a rate appr. -10 ppb per km. During April
-May day by day the gradient was approaching zero and in early June CO
mixing ratio became close to constant throughout the troposphere. This
situation kept for one month. In July, however, the stability of CO profile
was disturbed; surface concentrations were at a low level, but total columns
increased. The only possible explanation was that layers of polluted air
appeared aloft. The most obvious origin of this enhanced CO was forest
fires: July and August are the months, when forest fires happen.
Therefore, it was demonstrated, that it is feasible to monitor vertical
CO distribution in the Arctic using standard surface sampling, which is
made by the NOAA facilities, supplemented by solar spectroscopy of moderate
resolution. Another important conclusion is that for the first time total
column spectroscopic measurements were compared to the most precise modern
gas-chromatographic analysis. The comparison gave very meaningful results.
Successful validation of the MAPS instrument.
In 1994 we took part in spectroscopic validation of MAPS/Endeavor spring
and fall missions (Pougatchev et al., 1997). CO was measured simultaneously
with space measurements, first results were transmitted to Houston and
compared almost on-line with data of these two missions. Following comparison
revealed a good correlation (with an exception of the fall Kislovodsk data,
which are now under a reprocessing). There were some conclusions, made
as a result of this job. First, it is impractical to validate space-borne
measurements from a strongly polluted site. Second, if an information on
vertical CO distribution (even rough) is available, the problem of validation
can be resolved with an accuracy of a few percent. Zvenigorod was found
to be a typical mid continental site, quite suitable for a validation campaign.
Kislovodsk, as a mountain station locates in a fairly clean area and also
can be used for this purpose. A very lucky circumstance is that NOAA/CMDL
undertakes a program of systematic aircraft sounding of the atmosphere
close to Zvenigorod and plan to continue it next year (P.Novelli, personal
communication).
EXPERIMENTAL TECHNIQUES
Spectra of solar radiation are recorded by an Ebert/Fastie-type spectrometer
of 855 mm focal length with a grating of 300 groove mm-1 , equipped
by a solar tracker. The instrument was designed and constructed at the
Institute of Atmospheric Physics, Moscow, Russia [Dianov-Klokov, 1984].
It provides a resolution nearly 0.2 cm-1 in the 2160 cm-1 spectral region.
It has a Peltier cooled PbSe detector and a PC-based data acquisition system.
A spectrum between 2153.0 cm-1 and 2160.0 cm-1 is recorded every 3 min.
The retrieval algorithm, an improvement of our previous manual procedure
[Dianov-Klokov et al., 1989], is a modification of the "curve-of-growth"
technique. To ensure a consistency with other standard retrieval algorithms
a set of reference absorption spectra with triangle apodization and resolution
of 0.0035 cm-1 for the entire atmosphere for varying temperature/humidity
conditions were calculated. SFIT program (version 1.09d) [Rinsland et al.,
1982] in "zero-iteration" mode (i.e., without fitting calculated spectra
to observed ones) and HITRAN 1992 database were used for this purpose.
The entire atmosphere was assumed to be uniformly mixed for CO. These spectra
were convolved with the instrumental function of our grating spectrometer
of 0.2 cm-1 in width. Integrated absorptions (or equivalent
widths, EQW) of the CO R(3) line near 2158.300 cm-1 and the
H2O line near 2156.564 cm-1 were determined from
calculated and measured spectra the same way. Namely, the lines of zero
absorption on the spectrum were assumed to pass through the intensity maxima
at the sides of spectral lines ("microwindows"). This procedure resolves
the problem of uncertainty in zero absorption line for a measured spectrum
and makes it possible a direct comparison of the results to retrievals
made by the SFIT code. First, the program determines the total column amount
of H2O, comparing measured and calculated EQWs of the H2O
line. This value is used for correcting the EQW of the CO line, since it
is overlapped by a weak H2O line near 2158.105 cm-1.
Absolute accuracy of the spectroscopic CO determination depends on the
accuracy of spectral parameters from the HITRAN; a comparison between different
versions of this compilation shows that this does not exceed a few percent.
To compare the CO total column abundance with the in-situ measurements,
the former is presented here as weighted mean mixing ratio in parts per
billion in mole fraction. These values are close to the mean mixing ratios
for the troposphere; for typical profiles they are 2-8% less than the tropospheric
means. One should multiply this by 2.124 1016 to convert into
weighted total column amount (in mol/cm2 ). To get the tropospheric
part of the total column abundance in mol/cm2 with the tropopause
assumed at 265 mb, it should be multiplied by 1.54 1016.
The technique for the measurements of methane total column abundance
is principally similar to that for CO. The line P(2) of the fundamental
CH4 band near 3,000 cm-1 is recorded. The resolution
of the spectrometer in this spectral region is about 0.3 cm-1.
In addition to described techniques standard fitting procedures will
be applied to spectra for a comparison and intercalibration.
Second, the data obtained by a spectrometer in Zvenigorod, Russia(55.67œ
N, 36.83œ E, 200 m asl.). would be compared to CO vertical profiles, measured
using an aircraft, hired by NOAA/CMDL (Dr. Paul Novelli has expressed his
interest to do it). Analysis of the collected air samples is supposed to
be done by NOAA.
The validation work itself will start in Russia, both at Zvenigorod
and in Kislovodsk, Caucasus Mountains (43.83 N, 42.73œE, 2,100 m asl.)
just after the launch of the EOS platform and will be in progress for two
years. The total column CO and CH4 values over Zvenigorod will be compared
to aircraft CO and CH4 profiles. Results of measurements will
be transmitted to NASA as soon as the spectra are processed (as a rule,
in several hours).
In Canada during the validation phase of the work the spectrometer is
planned to be installed at the station Fraserdale, (49.53œ N, 81.37 œ W),
operated by AES of Canada (a preliminary consent to this collaborative
work is expressed by the head of this network Dr. Neil Trivett). In summer
increased total column CO abundances are expected at this site in some
days due to forest fires. Quite unusual vertical CO distributions are expected
sometimes over all the sites. A high degree of CO variability (appearances
and disappearances of lifted polluted layers) require a constant measurements
in these places. Of course, it is impossible to maintain such a high frequency
of aircraft sounding.
As a result of the first year CO total column amounts will be derived
at two sites in Russia and one site in Canada. These values will be compared
with available surface and/or vertically resolved mixing ratios. The period
of concurrent measurements will cover fall conditions. During the second
year of the project it is planned to continue validation and to obtain
data for winter, spring and summer atmospheric conditions.
FUNDING
Activities both in Russia and in Canada will be funded by national institutions.
A letter from the PI of MOPITT, Professor of Physics J.Drummond is attached.
A corresponding letter from the Russian participant will be sent to NASA
until the end of May, 1997.
REFERENCES
Dianov-Klokov, V.I., Spectroscopic studies of gaseous pollutants in the atmosphere over large cities, Izv. Acad. Sci. USSR, Atmos. Oceanic Phys., Engl. Transl., 20, 883-900, 1984.
Dianov-Klokov V.I. and L.N.Yurganov , 1981, A spectroscopic study of the global space-time distribution of atmospheric CO. Tellus, v.33, 262-273
Dianov-Klokov,V.I., L.N. Yurganov, E.I. Grechko, and A.V. Dzhola, Spectroscopic measurements of atmospheric carbon monoxide and methane. 1: Latitudinal distribution, J.Atmos.Chem. 8, 139-151, 1989
Dlugokencky, E. J., E.G. Dutton, P.C. Novelli, P.P. Tans, K.A. Masarie, K.O. Lantz, and S. Madronich, Changes in CH4 and CO growth rates after the eruption of Mt.Pinatubo and their link with changes in tropical tropospheric UV flux, Geoph. Res. Lett. 23, 2761-2764, 1996
Dvoryashina E.V., V.I. Dianov-Klokov and L.N. Yurganov, On the variations of total column carbon monoxide during 1970-1982, Izv. Acad. Sci. USSR, Atmos. Oceanic Phys., Engl. Transl. 20, 27-33, 1984.
Harris, R.C. et al. Carbon monoxide and methane over Canada: July-August 1990, J. Geophys. Res. 99, 1659-1670, 1994.
Khalil, M.A.K. and R.A.Rasmussen, Global decrease in atmospheric carbon monoxide concentration. Nature, 370, 639-641, 1994.
Mueller J.-F.and G.Brasseur, IMAGES: a three-dimensional chemical transport model of the global troposphere, J. Geophys. Res. 100, 16,445-16,490, 1995
Novelli, P.C., K.A. Masarie, P.P. Tans, and P.M. Lang, Recent changes in atmospheric carbon monoxide, Science 263, 1587-1590, 1994.
Pougatchev N.S., et al., 1997, Carbon monoxide ground-based infrared solar spectroscopic measurements during 1994 MAPS flight, J.Geophys. Res., 1997 (submitted).
Rinsland, C.P., M.A.H. Smith, P.L. Rinsland, A. Goldman, J.W. Brault, and G.M.Stokes, Ground-based infrared spectroscopic measurements of atmospheric hydrogen cyanide, J. Geophys. Res. 87, 11,119-11,1251, 1982.
Shaw, J.H., The abundance of atmospheric carbon monoxide above Columbus, Ohio, Astrophys. J., 128, 428-440, 1958.
Yurganov L.N., E.I.Grechko, A.V.Dzhola. Carbon monoxide and total ozone in Arctic and Antarctic regions: seasonal variations, long-term trends and relationships. The Science of the total environment 16O/161 (1995),831-84O.
Yurganov L.N., E.I. Grechko, and A.V. Dzhola, 1997a, Variations of carbon monoxide density in the total atmospheric column over Russia between 1970 and 1995: upward trend and disturbances, attributed to the influence of volcanic aerosols and forest fires, Geoph.Res.Lett., 10, 1231-1234
Yurganov L.N., D.A. Jaffe, E. Pullman, and P.C. Novelli, 1997b, Total column and surface densities of atmospheric carbon monoxide in Alaska, 1995, J. Geophys. Res., (submitted)
Zander, R., P.Demoulin, D.H.Ehhalt, U.Schmidt, and C.P.Rinsland, Secular
increase of total vertical column abundance of carbon monoxide above central
Europe since 1950, J.Geophys.Res., 94 , 11021-11028, 1989.
TITLE: Visiting Professor, Department of Physics, University of Toronto, Canada.
DATE OF BIRTH: December 8, 1944.
EDUCATION
PhD., Atmospheric Physics, Institute of Atmospheric Physics, Moscow, USSR. May 1979
M.Sc., Physics, Atmospheric Optics, Leningrad State University, Leningrad,
USSR. Febr. 1969
AREA OF EXPERTISE: Atmospheric background composition, IR spectroscopy,
UV and chemiluminescent techniques
PROFESSIONAL EXPERIENCE
Visiting Scientist, Geophysical Institute, University of Alaska, Fairbanks, March 1995 -Febr. 1997
Senior Researcher, Arctic and Antarctic Research Institute, St.Petersburg, June 1986-March 1995
Senior Researcher, Institute of Atmospheric Physics, USSR Academy of Sciences (IAP), Moscow, Sept. 1980- June 1986.
Junior Researcher (IAP), March 1969-Sept. 1980
PRINCIPAL PUBLICATIONS
1.Dianov-Klokov V.I. and L.N.Yurganov , 1981, A spectroscopic study of the global space-time distribution of atmospheric CO. Tellus, v.33, 262-273
2. Dianov-Klokov V.I. and L.N.Yurganov, 1989, Spectroscopic measurements of atmospheric carbon monoxide and methane. 2: Seasonal variations and long-term trends. J.Atmos.Chem., 8: 153-164.
3. Yurganov,L.N., 1990, Surface layer ozone above the Weddell Sea during the Antarctic spring. Antarc. Sci., 2, 169-174.
4. Yurganov L.N. and V.F.Radionov, 1991, Variations in the total column abundances of atmospheric carbon monoxide and methane in the polar regions. Antarc. Sci., 3: 443-449.
5. Yurganov L.N. 1993. Long-term vartiations of some tropospheric trace gases in 1980s: an influence of stratospheric ozone. J. Ecol. Chem., No 4, 274-278.
6. Yurganov L.N., E.I. Grechko, and A.V. Dzhola, 1997, Variations of
carbon monoxide density in the total atmospheric column over Russia between
1970 and 1995: upward trend and disturbances, attributed to the influence
of volcanic aerosols and forest fires, Geoph.Res.Lett., 10, 1231-1234
NAME: Eugeny Ivanovich GRECHKO, Co-investigator
TITLE: Head of Atmospheric Spectroscopy Laboratory, Chief of Zvenigorod
Scientific Station of the Institute of Atmospheric Physics (IAP), Russian
Academy of Sciences, Moscow, Russia
DATE OF BIRTH: January 2, 1947
EDUCATION
PhD ( Kandidat of Physics/Mathematics) Institute of Atmospheric Physics, USSR Academy of
Sciences, Moscow, USSR, March 1978
M.S., Institute of Fine Mechanics and Optics, Leningrad, USSR, May,
1971
PROFESSIONAL EXPERIENCE
Head of Atmospheric Spectroscopy Laboratory, IAP, Chief of Zvenigorod Scientific Station , Nov. 1985 - present
Senior Researcher, IAP, May 1978- Nov.,1985
Junior Researcher, , Institute of Atmospheric Physics USSR Academy of
Sciences, Moscow, USSR, June 1971- May, 1978
AREA OF EXPERTISE: Atmospheric physics and spectroscopy, tropospheric
chemistry
PRINCIPAL PUBLICATIONS
1. Dianov-Klokov ,V.I., L.N.Yurganov, E.I.Grechko, A.V.Dzhola, 1989. Spectroscopic measurements of atmospheric carbon monoxide and methane. 1: Latitudinal distribution. J.Atmos.Chem.8: 139-151
2.G.S.Golitsyn, E.I.Grechko, N.F.Elansky, N.S. Pugachev. Some Soviet measurements of trace gases. Tellus.43AB,164-175,1991.
3. E.I.Grechko, A.V.Dzhola. Spectroscopic measurements of total content CO,CH4,N2O at Central Arctic (Station SP-28). Izv.AN SSSR, Fizika atmospheri and okeana, v26,N5,p.547-550,1990.
4. L.N. Yurganov, E.I.Grechko, A.V.Dzhola. Carbon monoxide and total
ozone in Arctic and Antarctic regions: seasonal variations, long-term trends
and relationships. The Science of the total environment 16O/161
(1995),831-84O.
NAME:Anatoly Vasilievich DZHOLA
TITLE: Researcher, Institute of Atmospheric Physics, Moscow, Russia
DATE OF BIRTH: January 27, 1957
EDUCATION
M.S. Moscow Physical-Technical Institute, June 1973
PROFESSIONAL EXPERIENCE
Junior Researcher, August 1973- Sept. 1986
Researcher, Institute of Atmospheric Physics, Sept. 1986 - present
AREA OF EXPERTISE: atmospheric spectroscopy, tropospheric chemistry