A51C-0774 0800h
Upper Stratospheric/ Lower Mesospheric Ozone Profiles Retrieved From SCIAMACHY limb spectra: Brief Theory and First Validations; Observations of Ozone Depletion During the Solar Flare in Oct./ Nov. 2003
Ozone density profiles between 35 and 65 km altitude are derived from scattered sunlight limb radiance spectra measured by the SCIAMACHY instrument on the Envisat satellite. The method is based on the analysis of normalized limb radiance profiles in the Hartley absorption bands of ozone with selected wavelengths between 250 and 310 nm. It employs a non-linear Newtonian iteration version of Optimal Estimation (OE) coupled with the raditive transfer model SCIARAYS. The limb scatter technique combined with a classical OE retrieval in the short-wave UV-B and long-wave UV-C delivers reliable results. An overview of the methodology, of the most important sources of error and some first validation results are given. Ozone profiles retrieved from limb radiance measurements during the solar proton storm between 28 October and 6 November 2003 show depletion of ozone of about 60% at 50 km.
http://www.iup.physik.uni-bremen.de/~rohen/sciamachy/
A51C-0775 0800h
Comparison of ECMWF assimilated Ozone Data with Measurements
Assimilated European Center for Medium-Range Weather Forecasts (ECMWF) column ozone data is compared to the TOMS/SBUV Merged Ozone Data Set and the radiosonde data in the high latitudes of the Northern Hemisphere. The agreement is found to be excellent from 1979 to 1988 and from 1991 to 2002. For the two years 1989 and 1990, during which the assimilation was not used, the agreement is poor. This demonstrates the importance of assimilation. We also carried out a study of the temporal and spatial patterns of the interannual variability of total column ozone in the northern hemisphere polar region in the first versus the second period of the ECMWF assimilated data. The variability is closely associated with the dynamical forcing of the stratosphere by the troposphere via the divergence of the Eliassen-Palm flux.
A51C-0776 0800h
High Frequency GC/MS Measurements of CFCs, HCFCs, HFCs, PFCs and SF6 at Hateruma Island
In order to optimally determine the sources and magnitudes of halocarbons (CFCs, HCFCs, HFCs, PFCs, SF6 and some other anthropogenic halocarbons) in East Asia / Japan from the observations, we developed a new high frequency (hourly) monitoring system for the halocarbons, and have it run at Hateruma Island since 2004 spring. The system is based on a cryogen-free preconcentration and GC/MS. All the operations including calibration procedure with standards are automated, and occasional MS tuning or test runs are operated by remote-control. Sample air is flown from the tower top (40m high) at a large flow rate and a portion of it is supplied to the analytical system. Backtrajectory analyses have shown that enhancement of the halocarbons observed at Hateruma in 2004 spring was mostly attributed to the airmasses which had traveled over Shanghai or Taipei before arriving there.
A51C-0777 0800h
Atmospheric Burden of Some Ozone-Depleting Compounds Continues to Increase
With the signing in 1987 of the Montreal Protocol on Substances that Deplete the Ozone Layer, the international community began a series of steps to reduce the emission of ozone-depleting compounds into the atmosphere. As a result of these efforts, the contribution of these gases to the atmospheric burden of ozone-depleting halogen continued to increase until 1993-94, when their collective trend reversed and began to decline (Montzka et al 1996). This decline has continued over the past decade as anticipated by models of expected emissions. Not all contributing gases, however, are decreasing in atmospheric concentration. Mixing ratios of chlorofluorocarbon-12 (CFC-12), for example, have leveled off, but the turnover is slow, owing to the long lifetime and continued release of this gas from reservoirs such as foams and older automobile air conditioners. Mixing ratios of the two major halons (H-1301 and H-1211) continue to increase, albeit much slower than in the past. H-1301, with an atmospheric lifetime of 60y, is still used worldwide for lack of a suitable replacement, although its production ceased in developed countries in 1994 and was frozen in developing countries in 2002. Growth rates of shorter-lived (20 y) H-1211, which has replacements for some uses, have dropped some, but remain positive. The atmospheric mixing ratios of hyrdrochlorofluorocarbons, the intermediate replacements for CFCs, have been increasing rapidly over the past decade, but some are showing signs of leveling off. We examine here the current and potential future contribution of all of these gases to the burden of ozone-depleting halogen in the atmosphere, focusing on why they continue to increase.
A51C-0778 0800h
Evidence for O-Atom Exchange in the O($^1$D)~+~N$_2$O Reaction as the Source of Mass-Independent Isotopic Fractionation in Atmospheric N$_2$O
Recent experiments have shown that in the oxygen isotopic exchange reaction for O($^1$D)~+~CO$_2$ the elastic channel is approximately 50% that of the inelastic channel [{\it Perri et al.,} 2003]. We propose an analogous oxygen atom exchange reaction for the isoelectronic O($^1$D)~+~N$_2$O system to explain the mass-independent isotopic fractionation (MIF) in atmospheric N$_2$O. We apply quantum chemical methods to compute the energetics of the potential energy surfaces on which the O($^1$D)~+~N$_2$O reaction occurs. Preliminary modeling results indicate that oxygen isotopic exchange via O($^1$D)~+~N$_2$O can account for the MIF oxygen anomaly if the oxygen atom isotopic exchange rate is 30-50% that of the total rate for the reactive channels.
A51C-0779 0800h
Global Trends and Distributions of Atmospheric Nitrous Oxide
Atmospheric nitrous oxide (N2O) is a trace gas (2003 global mean = 318 parts-per-billion (ppb)) that is involved in global warming and stratospheric ozone depletion. It is the major source of stratospheric nitric oxide (NO). Tropospheric and stratospheric measurements show that N2O contributes about 1600 Mtons of N2O as nitrogen (N) to the atmosphere. Observed tracer-tracer correlations in the stratosphere suggest that the lifetime of stratospheric N2O is about 125 years. As no other major sink has been identified, this sink represents a total estimated removal of N2O of 13 Mtons (N) per year. Many types of natural (land and water) and man-made sources for atmospheric N2O exist, but there is considerable uncertainty in the magnitudes of these sources. Previously published work has shown that the relative strength of the oceanic source to the natural land source is between 20 and 40%. The tropics appear to be a strong source region. Most studies scale the magnitudes of these sources against the better-known total atmospheric sink. Over the long-term, the atmospheric growth rate or trend of N2O has averaged about 0.75 ppb per year, or about 5 Mtons (N) per year. However, there is considerable year-to-year variability in the global trend, which ranges from 0.27 to 1.4 ppb per year since 1988 when high precision in situ measurements began at CMDL. The growth rate appears to be affected by El Niño Southern Oscillation (ENSO) events. We will present both flask and in situ measurements from the NOAA/CMDL network to examine the uncertainties in the N2O budget. Comparisons of data with other networks including Advanced Global Atmospheric Gas Experiment (AGAGE) and the Carbon Cycle Greenhouse Gas (CCGG) of CMDL will be presented.
http://www.cmdl.noaa.gov/hats
A51C-0780 0800h
The NOAA Nitrous Oxide Calibration Scale
The nitrous oxide (N2O) calibration scale developed by the NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) was recently adopted by the WMO Global Atmosphere Watch (GAW) Program as the GAW N2O reference scale. NOAA/CMDL, along with the WMO GAW World Calibration Center (Garmisch-Partenkirchen, Germany), will likely be responsible for calibrating secondary compressed gas standards for a number of laboratories around the world. For N2O measurements made by different laboratories to be useful in examining global sources and sinks of N2O, inter-laboratory comparability must be within 0.2 ppb. To meet this stringent requirement for reproducibility, we configured an electron-capture gas chromatograph specifically for analysis of N2O comprssed gas standards. The NOAA calibration scale is maintained on this instrument through bi-monthly analysis of 5 secondary standards consisting of blends of natural and ultra-pure air (260-350 ppb N2O). Results from comparisons of these and other secondary standards on three N2O GCs operating in our laboratory suggest that the reproducibility of NOAA N2O calibrations can be maintained at or below 0.2 ppb. It is expected that this can be improved to 0.1 ppb through modest improvements in precision.
A51C-0781 0800h
Using MOZAIC Measurements in the Upper Troposphere to Test for Photochemical Bias from Met Fields in the UCI CTM (GISS, Oslo/EC) and NASA GMI (GISS, DAO, CCM3) Models.
Our purpose in studying the MOZAIC (Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft) datasets was to better characterize the upper tropical troposphere by analyzing the water vapor, temperature, and O3 measurements, identifying statistical relationships between the different parameters, and comparing the measurements with model results. From August 1993 to December 2003, data from 21,902 flights had been collected, with approximately 90% of the sampling atcruise altitudes along seven near-constant pressure levels between 300hPa and 200hPa (i.e...~8-12km), and approximately 10% of the sampling occurring in the tropics. Because water vapor is tightly coupled with OH production, and temperature and water vapor are coupled with HOx and NOx chemistry, the MOZAIC data were analyzed for trends in interannual variability, seasonality, and covariance of temperature, water vapor, and ozone in the upper tropical troposphere. Comparison of the high frequency MOZAIC data sampled along cruise altitudes with the meteorological fields used in chemical transport models specifically the European Center and the NASA-GISS GMI meteorological fields), provided a clean test for biases in model representation of atmospheric mixing and turnover rates. Study of the MOZAIC data showed that within the upper Tropical troposphere, temperature has very little seasonality or variability, water vapor shows strong seasonality and variability, and the largest discrepancies between the MOZAIC data and the models were with water vapor.
A51C-0782 0800h
Ideal Spatial Resolution of Satellite Observed Ozone in the Lower Troposphere
Satellite observations have the potential to accurately portray atmospheric chemistry and air quality. A proper spatial resolution of space based observations is critical to effectively observe air quality. The goal of this project was to find the ideal spatial resolution for satellite observations of ozone in the lower troposphere. Variograms, a plot of spatial dependence, were created to calculate the spatial length scale of ozone in the lower troposphere in a set of sensitivity experiments from a mesoscale meteorological model (MM5) and an air quality model (CAMx) set of simulations at 4, 8, 12, and 16 km resolutions. Variograms were created to find the spatial dependence of ozone in the east-west and north-south directions according to each CAMx simulation. In the east-west direction the variograms' spatial length scale converges at 60 km as the model simulations decreased from 16 to 4 km, so the length scale of spatial dependence in the east-west direction is 60 km. In the north-south direction the length scale is of similar magnitude but there is no spatial length scale convergence. Therefore, it would be helpful to have more air quality simulations at lower resolutions until a convergence is seen to determine the ideal spatial resolution in the north-south direction. However, the spatial length scale in the north-south direction was equal or greater than 60 km for all resolutions and greater than 60 km for the 4 km simulation. So, the analysis indicates that the smallest length scale is in the east-west direction at 60 km. According to the Nyquist sampling theorem, satellite platforms should have a spatial resolution of at least 30 km to effectively monitor ozone in the lower troposphere, and preferably of around 10 to 15 km.
A51C-0783 0800h
The characteristics for the seasonal variation of tropospheric ozone from ozonesounding measurements over Pohang, Korea
This study presents the first analysis of vertical ozone sounding measurements over Pohang, Korea. The main focus is to analyze the seasonal variation of vertical ozone profiles and find what controls the ozone seasonality. The maximum ozone at surface and in the free troposphere is observed in May and June, respectively. In comparison with ozone seasonality at Oki (near sea level) and Happo (altitude of 1840m) in Japan, which are located at the same latitude as of Pohang, we have found that the month occurring ozone maximum at Japanese sites is always a month earlier than that at Pohang. The analysis of wind flow at surface shows wind shift from westerly to southerly in May over Japan, but in June over Pohang. However, this wind shifts above boundary layer occurs a month later. This wind shift results in decreasing significant amounts of ozone because southerly wind brings clean wet tropical air. It has been suggested that spring ozone maximum in the low troposphere is due to polluted air transporting from China. However, enhance ozone amounts over free troposphere in June appears to have different origin. The feature of tongue-like structure in time-height cross-section of ozone concentrations, which starts from the stratosphere and extends to the middle troposphere, suggests that the ozone enhancement occurs due to gradually migration of ozone from the stratosphere. High frequency of dry air with elevated ozone concentrations in the upper troposphere in June suggests that the air is transported from the stratosphere. The HYSPLIT trajectory analysis supports that enhanced ozone in the free troposphere is not likely due to transport from the source of anthropogenic activity.
A51C-0784 0800h
The budget of atmospheric methyl chloride using stable carbon isotopic mass-balance approach
The atmospheric budget of methyl chloride (CH$_{3}$Cl), an ozone-depleting gas, is highly uncertain as yet. Although biomass burning, tropical plant, and ocean have been identified as the major sources, each contribution to atmospheric CH$_{3}$Cl is not well understood. In recent studies, much more contributions from tropical plant are suggested to balance the atmospheric CH$_{3}$Cl budget. An isotope mass-balance approach that utilizes differences in the stable carbon isotopic compositions ($\delta$$^{13}$C) of CH$_{3}$Cl in sources can provide useful clues to determine atmospheric budget. Previous studies revealed that, while atmospheric CH$_{3}$Cl exhibited $\delta$$^{13}$C values around -36 $\permil$VPDB, the representative source materials, biomass burning and tropical plant, exhibited substantially lower $\delta$$^{13}$C values of -38~-68 $\permil$VPDB, and -62~-73 $\permil$VPDB respectively. The discrepancy is too large to be explained by the kinetic isotope effect (KIE) during the removal of atmospheric CH$_{3}$Cl, so that we must assume the other significant CH$_{3}$Cl source that have rather $^{13}$C-enriched $\delta$$^{13}$C value. In recent study, we developed a new analytical system, which enable us to determine the $\delta$$^{13}$C values of CH$_{3}$Cl using continuous-flow isotope ratio MS (CF-IRMS), even when a sample contain substantial amounts of unsaturated hydrocarbons. In this study, we determined the $\delta$$^{13}$C values of CH$_{3}$Cl from ocean for which we have no available $\delta$$^{13}$C data. In addition, we determined those from biomass burning and tropical plants to reconfirm the reported $\delta$$^{13}$C values from them. To determine the $\delta$$^{13}$C values of CH$_{3}$Cl from ocean, we analyzed extracted gases from surface water on both coastal ocean in Japan and open ocean in NW Pacific. To determine the $\delta$$^{13}$C values of CH$_{3}$Cl from biomass burning, we analyzed biomass burning exhaust emitted from pinewood (C3 plant), rice (C3 plant), and maize (C4 plant). To determine the $\delta$$^{13}$C values of CH$_{3}$Cl from tropical plant, we analyzed gas samples emitted from tropical ferns and mangroves. In conclusion, our isotopic mass-balance calculation for CH$_{3}$Cl suggested that it is difficult to assume the studied C3 tropical plants as major CH$_{3}$Cl source. We must consider ocean and/or biomass burning as the major CH$_{3}$Cl sources, together with large average KIE of more than 5$\permil$ for the removal of atmospheric CH$_{3}$Cl. If such large average KIE would be difficult to assume, we must assume the other un-identified $^{13}$C-enriched sources (such as C4-plant burning) as an alternative major CH$_{3}$Cl source.
A51C-0785 0800h
$^{18}$O-depleted CO emission from boreal forest fire in Alaska
We determined the stable carbon and oxygen isotopic compositions of carbon monoxide (CO), together with those of methane and carbon dioxide, in Alaskan wildfire plume, and compared the results with those obtained during combustion experiment in the laboratory. Alaskan wildfire plumes were sampled during June, 2004, when the extensive wildfires were observed near Fairbanks, Alaska. Gas samples were collected in pre-evacuated 500ml glass bottles. The stable carbon and oxygen isotopic compositions of the trace gases were determined by using continuous-flow isotope ratio mass spectrometry, together with their mixing ratios. The gas samples were enriched in CO, ranging from 3.7 to 190 ppmv. Both carbon and oxygen isotopic compositions of CO exhibit homogeneous values of about -28 permil VPDB and about +8 permil VSMOW, respectively. The oxygen isotopic compositions are depleted in $^{18}$O relative to those emitted from high temperature combustion processes such as automobile exhaust and flaming biomass burning (more than +20 permil). Similar $^{18}$O-depleted CO is also observed in Siberian biomass burning plume (Bergamaschi et al., 1998). In order to clarify the origin of the $^{18}$O-depleted CO in the wildfire plumes, laboratory biomass burning experiments were carried out using a furnace of 50cm in both diameter and height. About 1kg of spruce, which is major in Alaskan forests, was burned and smoke gas samples were collected into glass bottles at 30-seconds to 3-minutes intervals. The results of the biomass burning experiment show that the stable carbon and oxygen isotopic compositions of CO and methane vary widely (about 20 permil) depending on their burning stages. During the flaming stage, CO and methane are enriched in $^{13}$C relative to carbon isotopic composition of fuel, whereas those are depleted in $^{13}$C during the smoldering stage. Similar trend was also found in the oxygen isotopic composition of CO. These variations in isotopic compositions are likely to be due to kinetic isotopic effects during both production processes and consumption processes (reaction with OH radical) of these gases. Based on these results, we conclude that most of carbon monoxide is emitted during the smoldering stage in the Alaskan forest fire. Besides, CO from boreal forest fire in general seems to be characterized by such $^{18}$O-depleted values of around +8 to +10 permil in atmospheric CO.
A51C-0786 0800h
Demonstration of a Modulated Fiber Laser Based Sensor for Measurement of Lower Tropospheric Column Carbon Dioxide Mixing Ratios
A unique, multi-frequency single beam, laser absorption spectroscopy system for space-based measurements of carbon dioxide (CO$_{2}$) mixing ratios in the troposphere is described. This system utilizes a low power, sinusoidally modulated continuous wave (CW) telecom laser system at 1.57 $\mu$m with lock-in detection of the received signal coming from the high gain HgCdTe avalanche photodiode (APD) detector. This system differs substantially from a standard pulsed, high energy Differential Absorption Lidar (DIAL) system. As a consequence, a low power, small, light weight, highly reliable system is fielded where the large signal-to-noise ratio (SNR) of the on-line-to-off-line (on-off) ratio of CO$_{2}$ absorption lines is achieved by signal processing. Results are reported on ground and airborne testing of this system. This testing was done in concert with known quantities of CO$_{2}$ in a laboratory gas absorption cell where SNRs of the on-off ratio in excess of 1000 were obtained. The field data were obtained in conjunction with the in-situ measurements of temperature, pressure, relative humidity, and CO$_{2}$. For the 0.5 to 2 km paths used in the horizontal testing, turbulence was the dominant noise factor. The airborne testing included an in-situ determination of CO$_{2}$ by a high-precision LI-COR instrument (0.1 ppm) along with separate temperature and pressure measurements. The flights were over the Department of Energy's Atmospheric Radiation Measurement Central Facility (ARM-CF) site. Two spiral profiles above the ARM-CF were accomplished along with overpasses at 10.6 km and 7.6 km. The atmospheric data and airborne remote and in-situ CO$_{2}$ measurements were used in the data analysis. The data collected from these tests have enabled the validation of an end-to-end instrument performance model, which is being used to support design studies of future airborne and space-based CW CO$_{2}$ DIAL systems.
A51C-0787 0800h
Spectral line parameters for CO$_2$ bands near 4.8 $\mu$m
High-resolution spectra of CO$_2$ bands near 4.8 $\mu$m m region were obtained by using a Bruker IFS 120HR spectrometer. In this study, we measured the line strengths and half-widths of the (11101-00001), (11102-00001), (20001-01101), and (12201-01101) bands of CO$_2$. Two weak hot bands [the (20001-01101) and (12201-01101) bands] are overlapped with the strong (11101-00001) band, thus the spectrum of CO$_2$ near 4.8 $\mu$m showed a complicated feature. The spectra were measured with a resolution of 0.01 cm$^{-1}$ and in the wavelength region of 4.6 to 5.4 $\mu$m. Six different combinations of CO$_2$-N$_2$ and CO$_2$-O$_2$ mixtures with a total pressure of 380 torr were used for the measurements. The sample pressure was measured with an MKS Baratron pressure gauge with a 1000-torr head. Measurements were performed using a 658.4 cm-long cell with CaF$_2$ windows. The temperature of the sample gas was measured with a thermocouple and was kept at 299K during the measurement. A nonlinear least-squares fitting procedure is used to determine the line strengths and half-widths of the above bands. As a result of the analysis, the squares of the vibrational dipole moment and the coefficients of the Herman-Wallis factor for these bands are derived. Obtained values were compared with the values in the HITRAN database. The (11101-00001), (11102-00001), (20001-01101), and (12201-01101) bands of CO$_2$ reveal remarkable contrast in intensity perturbations, i.e. enhancing the P-branch intensity while reducing that of the R-branch. These strong perturbations are caused by a Coriolis interaction. We take into account this interaction by introducing the Coriolis interaction coefficients and the values of these coefficients for CO$_2$ bands are determined. Observed and calculated values of the Coriolis interaction coefficients are compared for these bands.
A51C-0788 0800h
Sensor Specification Demand of a Nadir Looking SWIR FTS Aboard GOSAT to Monitor CO$_2$ Column Density in the Clear Sky Condition
Greenhouse gases Observing Satellite (GOSAT) will be launched in 2008 to monitor column density of green house gases such as CO$_2$ and CH$_4$ globally. A nadir-looking Fourier-Transform Spectrometer (FTS) which covers Short Wavelength Infrared (SWIR; 1.6 $\mu$m and 2.0 $\mu$m) and 0.76 $\mu$m oxygen A-band regions will be mounted on GOSAT. The 1.64 $\mu$m absorption band of CH$_4$ is used to estimate methane density. The SWIR FTS will measure surface scattered and sun-glint solar light. National Institute for Environmental Studies (NIES) has been carrying out researches on sensitivity and error analyses, data retrieval algorithm study, ground-based/air-borne validation measurements, and a plan of inverse model study to estimate distribution of source/sink amount of CO$_2$ in sub-continental scale. The possible error sources for estimating CO$_2$ and CH$_4$ column density are aerosols, cirrus clouds, water vapor, surface pressure (altitude), broken clouds, surface albedos, line parameters of absorption gases. Among them, aerosols and cirrus clouds are major error sources because they would affect baseline variations in measured radiances and distort gas absorption spectra. Portion of broken clouds in the FTS field of view will be estimated with a GOSAT aerosol-cloud imager. A minimum criterion of the GOSAT project is to observe spectra and estimate CO$_2$ column density within 1% error at least in the clear sky condition. According to our numerical simulation test results, we recommend that the specification demand of the GOSAT SWIR FTS should be a finer spectral resolution of 0.2 cm$^{-1}$ and a larger signal to noise ratio of 300. The reasons why we have recommended this specification will be presented here.
A51C-0789 0800h
Retrieval Precision Tests of CO$_{2}$ Column Amount from Simulated Data of the GOSAT SWIR FTS by Applying Rodgers_f Method
A SWIR (Short Wavelength InfraRed) FTS sensor aboard GOSAT (Greenhouse gases Observing Satellite) will measure CO$_{2}$ and CH$_{4}$ column amounts from space. The measurement geometry is a nadir looking observation of solar-lights scattered by ground-surfaces. The measurement spectral regions are 2.0 micron band (4710 - 5320 cm$^{-1}$), 1.6 micron band (5500 - 6535 cm$^{-1}$), and 0.76 micron band (12755 - 13280 cm$^{-1}$) for CO$_{2}$ and CH$_{4}$ column amount estimation. We have performed sensitivity studies and error analyses by using computer simulation data of the FTS outputs in order to investigate retrieval algorithms. The algorithms used for the error estimation mainly consist of two parts; the radiative transfer calculation part and the retrieval part. In the former part, HSTAR code, which is based on the RSTAR code developed by T. Nakajima_fs group at CCSR, is used. HSTAR simulates total radiance with high spectral resolution by line-by-line calculation. Rayleigh scattering and the path-radiance effects caused by aerosols and clouds are considered in the HSTAR. As for the retrieval part, we have tested Rodgers' optimal estimation method, which utilizes a priori knowledge on targets (e.g., climatological data). Some possible error sources of the CO$_{2}$ and CH$_{4}$ measurement in the SWIR region are aerosols, cirrus cloud, water vapor, surface pressure (altitude), surface albedos, temperature profile, and the line parameters of absorption gases. In case of aerosols or cirrus clouds are contaminated in the measurement field of view, retrieval precision strongly depends on the retrieval conditions; the target unknown parameters and constraint condition of a priori data. The results of error analyses under several retrieval conditions will be presented.
A51C-0790 0800h
Overview of Greenhouse Gases Observing Satellite (GOSAT) of Japan
The observation of CO$_2$ from space is one of the top priority subjects of the carbon cycle research. We proposed to use the surface scattered light observation in near infrared (1.6 $\mu$m and 2.0 $\mu$m) by Fourier transform spectrometer on a satellite, and this project has been approved by Space Committee of Japan. The observed spectra will proved us the column concentration of CO$_2$, but little information on the vertical profile, as long as the spectral resolution is not very high (0.2cm$^{-1}$) and the signal to noise ratio is limited (S/N of 300 is the target value). The precision will exceed to 1% and our science team target is 0.3%. This value is far below the precision of in situ observation. However, the improvement of carbon sink/source analysis is expected to be remarkable compared with the data analysis of the present surface CO$_2$ monitoring network data. The satellite is in polar orbit with three days recurrent rate, which results in 10 degrees interval longitudinally. The local time of observation will be around 1 p.m. in order to minimize the sampling time error. This project is conducted jointly by Ministry of the Environment, National Institute for Environmental Studies, and Japan Aerospace Exploration Agency.
A51C-0791 0800h
Anthropogenic Emissions of Non-Methane Hydrocarbons in the Northeastern U.S.: 10 Years of Measured Seasonal and Interannual Variations
Harvard Forest, a rural site in central Massachusetts located downwind of major urban-industrial centers, provides an excellent location to monitor anthropogenically emitted trace gases. Air that arrives at Harvard Forest from the southwest is affected by emissions from the east-coast urban corridor, and may have residual influence from emissions in the upper Ohio Valley and Great Lakes region further to the west. Pollution plumes that reach the site represent a homogenized mixture of regional anthropogenic emissions. Concentrations of C$_{2}$-C$_{6}$ hydrocarbons along with CO, NO$_{y}$ and CH$_{4}$ were measured nearly continuously from August 1992 through July 2002. By ratioing observed concentrations to acetylene, which is almost solely produced from fossil-fuel combustion processes, we are able to detect seasonal and interannual trends in relative emission rates for this series of trace gases. Furthermore, the variations in relative concentrations indicate seasonal shifts in decomposition and deposition rates for shorter-lived compounds. Seasonal changes in butane and isobutane emissions are dominated by changes in gasoline formulation that occur in the spring and fall transition. The seasonality of pentane, isopentane and hexane emissions is dominated by temperature driven evaporative processes. Emissions of ethane and propane lack seasonality and correlate less with acetylene than other gases, which indicate sources of these two gases are strongly influenced by relatively local liquid propane, wood combustion and/or natural gas emissions that are not associated with regional combustion sources. A strong seasonal shift in the CO to acetylene slope suggests that secondary production of CO from oxidation of primary hydrocarbons in the summer significantly contributes to regional CO concentrations. The slope of NO$_{y}$ to acetylene provides a better estimate of the fraction of NO$_{y}$ removed by deposition within the region during summer than compared to the slope to CO.
A51C-0792 0800h
Trace gas and Particulate Emissions From the 2003 Southern California Wildfires
Thirteen major wildfires in Southern California, fanned by warm and dry Santa Ana winds in late October 2003, had a large impact on atmospheric chemistry and air quality in an urban area populated by $\sim$20 million people. To quantify some of the atmospheric effects of these wildfires, which burned over 300,000 hectares of mainly chaparral and woodlands, continuous in-situ trace gas and particle measurements were carried out at our laboratories in La Jolla. During the fires we observed elevated levels of non-methane hydrocarbons and methyl halides with up to $\sim$8 ppb C$_{2}$H$_{2}$, $\sim$25 ppb C$_{2}$H$_{4}$, $\sim$42 ppb C$_{2}$H$_{6}$, $\sim$9.2 ppb C$_{6}$H$_{6}$, $\sim$2 ppb C$_{7}$H$_{8}$, and $\sim$2.6 ppb CH$_{3}$Cl (all GC/MSD). In addition, up to $\sim$4 ppm CH$_{4}$ (GC/FID), $\sim$476 ppm CO$_{2}$ (NDIR), and a concomitant reduction of O$_{2}$/N$_{2}$ ratios (fuel cell oxygen analyzer) were observed together with a high degree of correlation among all species. The tightest correlations were observed for compounds typically emitted by the smoldering phase of a fire. Emission ratios relative to C$_{2}$H$_{6}$ ($\Delta$X/$\Delta$C$_{2}$H$_{6}$) in mol/mol were 0.64$\pm$0.01 for C$_{2}$H$_{4}$ (r$^{2}$ = 0.97), 0.172$\pm$0.003 for C$_{6}$H$_{6}$ (r$^{2}$ = 0.97), 0.0484$\pm$0.0006 for CH$_{3}$Cl (r$^{2}$ = 0.98), and 45.0$\pm$1.6 for CH$_{4}$ (r$^{2}$ = 0.91). Although correlations of these gases with CO$_{2}$ show more scatter, they provide a mechanism for quantifying trace gas fluxes relative to the amount of biomass burned. Additionally, on-line real-time measurements of the concentrations of particles with scanning mobility particle sizer (SMPS, 0.01-0.3 $\mu$m) and aerodynamic particle sizer (APS, 0.54-2.46 $\mu$m) showed a high degree of correlation with trace gases mixing ratios as well, pointing to the wildfires as the common source. The chemical compositions of individual aerosol particles determined by an aerosol time-of-flight mass spectrometer (ATOFMS) confirmed that $\sim$70 % of particles in the 0.05-1 $\mu$m aerodynamic diameter range had typical biomass burning signatures with levoglucosan and high potassium contents. Levels of particulate matter with aerodynamic diameters $\le$2.5 $\mu$m (PM$_{2.5}$), which are according to the EPA closely associated with the aggravation of heart and lung diseases, were determined from the concentration of particles assuming spherical particles of 1.2 g/cm$^{3}$, and the EPA 24-hour limit for PM$_{2.5}$ of 65 $\mu$g/m$^{3}$ was considerably exceeded during two 24 hour periods with values up to $\sim$250 $\mu$g/m$^{3}$.
A51C-0793 0800h
Capturing the Signatures of the 1997 Indonesian Wildfires Present in the CARIBIC Observations With a Global Chemistry Transport Model
In the CARIBIC project, several flights with a passenger aircraft sampled air exposed to biomass burning events. One of these events includes the Indonesian wildfires of 1997. During flights from Munich to Male in November and December 1997, peak values of 230 ppbv were observed at cruising altitudes. Biomass burning is a major source of ozone precursors and aerosols, both major drivers of changes in radiative forcing. As biomass burning exhibits a large spatial and temporal variability that depends mostly on natural factors, its description poses a challenge for global chemistry transport models. Rather recently, several satellite observational products, such as active fire counts, aerosol absorbing index, and burned area, have become available that allow adequate description of the variability of biomass burning (e.g. Schultz, 2002; Duncan et al., 2003; Van der Werf et al., 2003). In this study we perform model simulations with the Tracer Model Version 4 (TM4) chemistry transport model to interprete the CARIBIC CO measurements. With a tagging technique we distinguish between industrial, biogenic, and biomass-burning contributions. We will test different (published) descriptions of biomass burning CO emissions based on the ATSR-2 fire count product. We will show that TM4 captures the signatures of the 1997 Indonesian wildfires rather well with these descriptions, and that the model results improve further if we apply a "daily" resolved biomass-burning emissions instead of the commonly used monthly resolved emissions. This "daily" resolution has been obtained by calculating 10-days backward moving-averages of the ATSR fire counts product.
A51C-0794 0800h
Atmospheric Deposition of Nitrogen and Sulfur to Lake Paldang in Korea
Lake Paldang, formed by a dam located on the Han River, is a main resource of drinking water for 20 million people in the greater Seoul area. The lake is surrounded by forests and farmland, but on the downwind side of prevailing westerlies from Seoul. It is suspected that the lake would have been affected by various pollutants from Seoul. In the present work, atmospheric deposition of nitrogen and sulfur was estimated by both measurement on the spot of Lake Paldang and prediction over the watershed. Wet and dry depositions were separately measured with wet-only and dry-only samplers, respectively since May 2002. The dry deposition sampler was composed of three pans filled with pure water. An average of concentration increase during the sampling period was considered as the input by deposition. Dry deposition was measured both routinely and intensively along with atmospheric concentrations. Wet deposition was measured either daily or event basis when precipitation occurred. Only dry deposition was predicted by season over the watershed of Lake Paldang with grid spacing of 12 km x 12 km. Models-3/Community Multiscale Air Quality with a updated aerosol module was used for air quality modeling. By assuming the same amount of wet deposition measured at Lake Paldang over the watershed, the contribution of atmospheric nitrogen to the total nitrogen load to Lake Paldang was estimated.
A51C-0795 0800h
Development of an Instrument for {\it in Situ} Atmospheric Laser-Induced Fluorescence Measurements of IO Using a Compact all Solid-State Titanium:Sapphire Laser System
Ozone loss over midlatitudes of the northern hemisphere is well documented in both the scientific literature and the public policy arena. Accurately defining secular trends in the distribution of ozone and establishing the mechanism responsible for the observed losses are two dominant and enduring issues. "Although the chemistry of chlorine and bromine in the stratosphere is reasonably well known, this is not the case for iodine" (WMO, 2002). It was speculated that the observed losses of ozone in the lowermost stratosphere might be due to the presence of IO in the 1 ppt range. While the preponderance of remote observations suggests that IO is probably not a significant contributor to ozone loss, a direct {\it in situ} measurement of IO in the lower stratosphere would, as an independent technique, bring closure to this issue. {\it In situ} IO measurements not only will be valuable in establishing the actual concentration of IO, but, depending on the observed variability of IO, may also well serve as an indicator of recent transport. All of the precursor species of inorganic iodine are exceedingly short-lived in the atmosphere. Thus, {\it in situ} IO observations may serve as tracers of recent convective activity, a subject of growing interest in the atmospheric community. Measuring IO {\it in situ} requires the sensitivity to detect sub parts per trillion mixing ratios of IO, which can be obtained with laser-induced fluorescence (LIF) using an approach similar to that of the OH and NO$_{2}$ LIF instruments operated in this lab. The IO LIF instrument takes advantage of the very high absorption cross section of the narrow single rotational lines of IO. Laser excitation is achieved using a frequency doubled, YAG pumped Ti:sapphire laser system optimized for narrow band operation (0.0008 nm) at 445 nm. Recent advances in solid state Nd:YAG laser technology have resulted in extremely small and efficient lasers. The Nd:YAG laser is only 4" by 7" by 2.5" and weighs less than 4 lbs. The entire optical footprint of the Nd:YAG/Ti:sapphire laser system currently being used is only 12.5" by 12.5" by 5". The overall efficiency of the laser system also allows for smaller power requirements and easier system integration.
A51C-0796 0800h
Development of Atmospheric Methane Sensor based on Tin-Dioxide Flammable Detector
A new atmospheric methane sensor has been developed based on a tin-dioxide natural gas leak detector. The sensitivity, stability and selectivity to methane have been improved by the removal of water vapor in the sample air by chemical desiccant, by the stabilization of temperature by heater/Peltier cooler controller, and by the removal of other flammable gases by Pt-black catalyzer, respectively. The system is very compact in size (W$\times$D$\times$H = 200$\times$250$\times$200mm) and light in weight (4kg). The power consumption is less than 10W. The precision of measurement was examined for six NIES standard gases of CH4 in air in the range of 1800ppb to 2000ppb, and the residual error was found to be within $\pm$ 10ppb. The concentration of CH4 in the urban air was compared between the results by the GC/FID system with those of our system operated in parallel, and an excellent linear relationship with a standard error of 4ppb was observed. This system works continuously, but we must wait for several minutes before a reliable value is obtained when the methane concentration changes drastically, which seldom occurs even in the polluted environment. This system is precise and stable enough to monitor the methane in the baseline atmosphere.
A51C-0797 0800h
Performance of an airborne White-Light Optical Particle Counter with an LED light source
The White-Light Optical Particle Counter (WLOPC) was designed to measure the particle size distribution in the range from 0.8 to 8 um on board the NOAA WP-3D research aircraft. Supermicron particles are quantitatively sampled using a Low Turbulence Inlet (LTI). To minimize particle losses during transport, the WLOPC optical detector is placed close to the LTI, while the control unit with computer, electronics, flow system and power supply is placed two meters away. The sample flow provided by the LTI is about 80 liter per minute by volume (lpmv), of which 4 lpmv are extracted to the WLOPC. To control the relative humidity this sample flow can be heated up to 50°C. The sample air enters the detection chamber through a nozzle sheathed by an addition flow of 4 lpmv. The resulting particle beam crosses a focused light beam from a broad-spectrum light-emitting diode (LED). The scattered light is reflected by an elliptical mirror onto a photo multiplier tube (PMT). The choice of a white light source and a large solid angle reduces the sensitivity to particle shape and refractive index and produces a monotonic output as a function of particle diameter. The PMT output is converted by a preamplifier and a logarithmic amplifier and analyzed for pulse amplitude. The pulse amplitude is calibrated using monodisperse particles of different compositions and binned into 30 channels. The first ambient measurements by the WLOPC were made on the NOAA WP-3D during the Intercontinental Transport and Chemical Transformation - New England Air Quality Study (ITCT-NEAQS 2004) in July and August 2004. Preliminary data from this mission will be presented.
A51C-0798 0800h
Initial Analysis of Atmospheric Emission Spectra Recorded at Arrival Heights and Amundsen-Scott South Pole Station: 2003-2004
The University of Denver Department of Physics and Astronomy placed Atmospheric Emission Radiometric Interferometers - eXtended (AERI-X) Fourier Transform Spectrometers (FTS) at Arrival Heights and Amundsen-Scott South Pole station during the Antarctic summer season of 2003-2004. Both instruments have been actively recording spectra since then. We will introduce the measurement program and present analyses of some of the spectra received before the stations closing for the 2004 winter. The analyses will include column amounts for CH$_{4}$, H$_{2}$O, HNO$_{3}$, O$_{3}$ and N$_{2}$O.
A51C-0799 0800h
Evaluation of a CIMS Technique used for Airborne Measurements of Ammonia during the New England Air Quality Study 2004
A Chemical Ionization Mass Spectrometer (CIMS) utilizing protonated acetone dimer ion chemistry was used to measure gas-phase ammonia (NH$_{3}$) aboard the NOAA WP-3D aircraft during the New England Air Quality Study (NEAQS) in July and August of 2004. The protonated acetone dimer reacts selectively and sensitively with NH$_{3}$ to form a stable cluster ion. Ambient NH$_{3}$ was measured once per second by monitoring this cluster peak. A PFA Teflon inlet designed and previously characterized for sampling nitric acid (HNO$_{3}$) was used. The instrumental background was determined by scrubbing NH$_{3}$ from ambient air using silicon phosphates that release phosphoric acid when exposed to ambient levels of humidity. Standard addition calibrations were performed periodically during each flight using an NH$_{3}$ permeation device whose output was monitored throughout the field campaign by UV optical absorption at 184.95 nm. Preliminary data indicate a typical sensitivity of 2 to 3 ion counts/s/pptv of NH$_{3}$. Instrumental background varied between flights and typically ranged from 0.5 to 1 ppbv. Characterization of this inlet for sampling NH$_{3}$ and analysis of instrument time response will be presented and compared to laboratory studies of different inlet materials. Preliminary observations of tropospheric NH$_{3}$ mixing ratios downwind of East coast urban regions will be described.
A51C-0800 0800h
Theoretical Calculations of Exchange Equilibria Involving Multiply-Substituted Isotopologues of Molecular Gases
Heavy stable isotopes are not randomly distributed among molecules in thermodynamically equilibrated mono-molecular gases (e.g., O$_{2}$, N$_{2}$, or CO$_{2}$), but instead preferentially concentrate into bonds with each other (e.g., $^{18}$O-$^{18}$O, $^{15}$N-$^{15}$N, etc.). This occurs because such bonds have exceptionally low zero point energies and thus are comparatively more stable. This zero point energy effect is subtle (typically at per-mil level) but has recently been shown to be measurable. The abundances of isotopologues of molecular gases containing more than one rare isotope (`multiply-substituted isotopologues') could be used for a variety of geochemical applications, including geothermometry, and such applications will require a sound understanding of these zero-point energy effects. This study presents methods and data for theoretically estimating the strength of these effects, and discusses possible applications. Accompanying abstracts by Afek et al., Eiler et al., Ghosh et al. and Schauble et al. provide analytical details, analogous models for condensed phases, and illustrative applications. We have derived a method for systematically evaluating the influence of the zero point energy effect in the abundances of all isotopologues in thermodynamically equilibrated populations of O$_{2}, CO, N$_{2}$, NO, CO$_{2}$ and N$_{2}$O between 1000 and 193 to 77 K. This method uses Urey-type algorithms (based on simple harmonic oscillator and rigid rotor model) to evaluate partition functions and equilibrium constants of isotope exchange reactions, and simultaneously solves for abundance of each isotopologue of a given molecule constrained by all independent equilibria. We also examine the accuracy of the Urey-type models by comparison with direct summations over all experimentally or empirically determined energy levels to calculate partition functions. This comparison is only made for CO and CO$_{2}$ due to limitations in spectroscopic data, but in these cases there are no significant differences among methods. Calculation results also show that, in most cases, multiply-substituted isotopologues are predicted to be enriched relative to stochastic (random) distributions by ca. 1 to 2 per mil at earth-surface temperatures. This deviation, defined as \Delta$_{i}$ for isotopologue i, generally increases linearly with 1/T at temperatures $<$ 500 K, and with 1/T$^{2}$ at temperatures $>$ 500 K. An exception is N$_{2}$O, which shows complex temperature dependences and 10's of per-mil enrichments or depletions of abundances for some isotopologues. These theoretical calculations provide a basis for discriminating between fractionations controlled by equilibrium thermodynamics and other sorts of isotopic fractionations in the budgets of atmospheric gases. Moreover, because abundances of multiply-substituted isotopologues in thermodynamically equilibrated populations of molecules vary systematically with temperature, they can be used as geothermometers. Such thermometers are unusual in that they involve homogeneous rather than heterogeneous equilibria (e.g., isotopic distribution in gaseous CO$_{2}$ alone, rather than difference in isotopic composition between CO$_{2}$ and coexisting water). Also, multiple, independent thermometers exist for all molecules having more than one multiply-substituted isotopologue (e.g., thermometers based on abundances of $^{18}$O$^{13}$C$^{16}$O and $^{18}$O$^{12}$C$^{18}$O are independent); thus temperatures estimated by this method can be tested for internal consistency.
A51C-0801 0800h
Multiply-Substituted Isotopologues of Molecular Gases: Instrumentation, Methods, and Illustrative applications
Molecules containing two or more heavy, rare stable isotopes (e.g., D$_{2}$; $^{15}$N$_{2}$) undergo distinctive physical, chemical and photochemical fractionations and could provide new, independent constraints on many geochemical problems. Until recently, these species have been un-analyzable at their low natural abundances. We configured a Finnigan Mat 253 gas-source mass spectrometer to measure the doubly-substituted isotopologues of CO$_{2}$, N$_{2}$O, O$_{2}$, N$_{2}$, and CO, with the aim of exploring their uses in geochemistry, including atmospheric chemistry. We describe this instrument, relevant methods and illustrative applications, focusing on measurements of the mass-47 CO$_{2}$ isotopologue, $^{13}$C$^{18}$O$^{16}$O. Accompanying abstracts by Afek and Eiler, Ghosh et al., Schauble et al. and Wang et al. present related theoretical and applied studies. The collection system of our instrument includes three faraday cups for masses 44, 45 and 46 registered through 10$^{8}$ to 10$^{11}$ Ohm resistors and three faraday cups for masses 47, 48 and 49 registered through 10$^{12}$ Ohm resistors. Duel-inlet measurements of $\sim$50 $\mu$mole samples produce $\sim$2 pA ion currents for mass 47. External precision for measurements of R$^{47}$ ($\sim$[$^{13}$C$^{18}$O$^{16}$O]/[$^{12}$C$^{16}$O$_{2}$]) varies with protocol, but is typically $\pm$0.03 to 0.02 $\permil$, 1$\sigma$. We report data for R$^{47}$ using a reference frame in which all C and O isotopes are randomly distributed among all possible isotopologues. We define the variable, $\Delta$$_{47}$, as the difference in per mil between the measured value of R$^{47}$ for a given sample and the value of R$^{47}$ expected for a random distribution in that sample. Values of $\Delta$$_{47}$ are standardized by comparison with an intra-laboratory standard that has a known bulk isotopic composition and that has been heated to make it take on the random distribution. External precision of $\Delta$$_{47}$ values for repeat measurements of purified CO$_{2}$ average $\pm$0.011 $\permil$, $1\sigma$. We infer that $\Delta$$_{47}$ values are more reproducible than R$^{47}$ values because analytical errors in R$^{45}$, R$^{46}$ and R$^{47}$ are correlated with one another (much as measurements of $\Delta$$^{17}$O are more precise than measurements of $\delta$$^{18}$O and $\delta$$^{17}$O). Sample contamination, particularly by hydrocarbons, is a pernicious problem; we will review experiments demonstrating their effects and methods for their removal. Multiply-substituted isotopologues generally have lower zero-point energies than their isotopically normal and singly-substituted relatives. Therefore, reactions such as: $^{13}$C$^{16}$O$_{2}$ + $^{12}$C$^{18}$O$^{16}$O = $^{13}$C$^{18}$O$^{16}$O + $^{12}$C$^{16}$O$_{2}$ generally are driven toward the right, so that a population of isotopologues at equilibrium generally has greater abundances of multiply-substituted isotopologues than predicted by the stochastic distribution. This effect is subtle (typically permil), but the external precision of our measurements indicates it could be used as a thermometer with temperature sensitivity as good as $\sim$1.5 $\deg$C. We will discuss further examples of isotopic variations observed or expected to arise from thermodynamics, (e.g., air-sea exchange) classical physical processes (e.g., diffusion; thermogravitation), and photochemistry (e.g., methane photolysis; ozone chemistry).