bluuebunny/crossref_metadata_2025 huggingface dataset:
Background tropospheric aerosols: Incorporation within a statistical‐dynamical climate model
Authors: Potter Gerald L. , Cess Robert D.
Published: February 2008

To evaluate the possible influence of natural background tropospheric aerosols upon the earth's present climate, we have incorporated aerosol radiation models for continental and maritime aerosols into the Lawrence Livermore National Laboratory statistical‐dynamical climate model. The model results suggest that background tropospheric aerosols produce 3°–4°C global surface cooling, with maximum cooling occurring at high latitudes, results which are essentially consistent with an energy balance climate model study by Coakley et al. (1983). To specifically delineate effects caused directly by the aerosols, as opposed to indirect effects resulting from aerosol‐induced climate change, a second climate perturbation was considered that consisted of reducing the solar constant so as to give exactly the same initial reduction in surface‐atmosphere solar absorption as for the inclusion of tropospheric aerosols. These separate climate perturbations produced nearly identical climate feedback effects, together with similar changes in atmospheric stability and hydrological cycle, despite the fact that the two perturbations have quite different latitudinal and vertical distributions. This finding is consistent with a general circulation model study by Manabe and Wetherald (1980) concerning perturbations of both atmospheric CO2 and the solar constant. A related conclusion is that the model's climate response to tropospheric aerosols is insensitive to the manner in which the aerosols are vertically distributed.
Solar Mesosphere Explorer Near‐Infrared Spectrometer: Measurements of 1.27‐μm radiances and the inference of mesospheric ozone
Authors: Thomas Ronald J. , Barth Charles A. , Rusch David W. , Sanders Ryan W.
Published: February 2008

Ozone in the mesosphere is determined from observations made by the near‐infrared spectrometer experiment on the Solar Mesosphere Explorer satellite (SME) between 50 and 90 km over most latitudes at 3:00 P.M. local time. The spectrometer measures emission from O2(1Δg) at 1.27 μm that is primarily due to the photodissociation of ozone. The instrument consists of a parabolic telescope that limits the field of view to less than 0.1°, an Ebert‐Fastie spectrometer, and a passively cooled lead sulfide detector system. The limb radiances, measured as the spacecraft spins, are inverted, producing volume emission rate profiles from which ozone densities are inferred. The vertical resolution is better than 3.5 km. The calculation of ozone accounts for quenching and atmospheric transmission of both solar radiation and 1.27‐μm radiation. We have established the existence of a secondary maximum of ozone density near 80km. An error analysis shows that the effects of random errors in the data and in the analysis on the final ozone profile are less than 10% between 50 and 82 km.
SAGE satellite observations of stratospheric aerosols from Mount St. Helens eruption: A two‐wavelength analysis
Authors: Lenoble J. , Pruvost P. , Brogniez C.
Published: February 2008

The Angström coefficient profiles deduced from 93 SAGE Satellite observations in July 1980 between 50°N and 70°N have been used to study the variation of the aerosol size distribution in the Mount St. Helens aerosol layer. In most cases a layer of large particles corresponding to the maximum extinction at 18–20 km is topped by a layer of small particles. The study of profiles averaged over 10° latitude bands for May to November 1980 have confirmed the extent of this situation, which contrasts with a rather constant size distribution within the unperturbed stratosphere in 1979. Assuming an equivalent log‐normal size distribution with an effective variance of 0.250, the logarithmic mode radius is found around 0.20 μm for the large‐particle layer and around 0.06 μm for the top layer. The inferred mass density profile is strongly influenced by this structure.
Aerosol size distributions in air masses advecting off the east coast of the United States
Authors: Hoppel William A. , Fitzgerald James W. , Larson Reginald E.
Published: February 2008

Accurate measurements of the size distribution of atmospheric aerosols in the size (radius) range from 0.006 to 2.5 μm made from a ship within 300 km of the east coast of the United States are presented. As air advects from land to sea, there is a rather rapid decay of particles smaller than 0.05 μm during the first day or so. After this initial decay of small particles the size distribution was often found to remain remarkably stable for hours. Significant changes in the size distribution were often associated with changes in air masses and meteorological conditions. Some of the changes can be explained qualitatively. Others, such as a pronounced double peak which occurred occasionally in the fine‐particle range, are more difficult to understand. Possible physical mechanisms which might produce a double‐peaked distribution are discussed, including the increase in the mass of cloud condensation nuclei as a result of the chemical formation of new material from gases absorbed in cloud droplets during a cloud formation‐evaporation cycle. Using the measured size distributions, volume extinction coefficients were calculated for the wavelength range 0.3–10 μm. The calculations compare favorably to the measured scattering coefficients at 0.55‐μm wavelength. Particles in the radius range 0.1–0.3 μm made the largest contribution to the total extinction at optical wavelengths on nearly all occasions.
Boron in the troposphere: Distribution and fluxes
Authors: Fogg Thomas R. , Duce Robert A.
Published: February 2008

Gaseous and particulate concentrations of atmospheric boron have been measured simultaneously for the first time at several marine and continental areas using an impregnated filter sampling technique. Rainwater boron concentrations were also determined. The data indicate that most of the atmospheric boron is present in the gas phase. Gaseous boron concentrations are higher over the ocean than over the continents. Particulate boron may have the opposite distribution. Gaseous boron concentrations are elevated in some urban continental areas, probably as a result of volatilization of boron during coal combustion. The concentration of boron in rain and on aerosol particles is similar at all locations, suggesting that scavenging of aerosol particle boron may control boron in rain even though a significant gas phase exists. Total gaseous boron emissions from all sources are estimated as 250–490×1010 g yr−1, and particulate boron emissions are estimated to be 32–88×1010 g yr−1. The major global sources of atmospheric boron appear to be volcanic emissions and sea salt aerosol production. The tropospheric residence time of gaseous and particulate boron is estimated to be 19–36 days and 2–6 days, respectively.
Tidal oscillations in the atmospheric sodium layer
Authors: Batista P. P. , Clemesha B. R. , Simonich D. M. , Kirchhoff V. W. J. H.
Published: February 2008

The vertical distribution of atmospheric sodium has been measured at São José dos Campos (23°S, 46°W) over a total of about 20 complete diurnal cycles between April and August 1981. Average time variations of the sodium density show strong oscillations with 12‐ and 24‐hour periods. Both the diurnal and semidiurnal components of the oscillation display large amplitudes and a 180° phase inversion near the layer peak. These features are interpreted in terms of the propagation of tides in the layer, taking into account the interaction between the tide and the minor constituent layer. It is shown that the vertical wind is the most important factor that determines the amplitude of the oscillation in sodium density at a fixed height, thus making it possible to estimate the phase and amplitude of the wind oscillations over a limited height range. Diurnal and semidiurnal vertical wind amplitudes of 2–6 cm s−1 and 5–20 cm s−1, respectively, have been inferred. The 12‐hour component shows vertical phase propagation with a wavelength of ∼50 km, in agreement with recent theories. The 24‐hour component, however, shows characteristics of an evanescent mode instead of the expected S1.1 mode. Maximum upward vertical velocity occurs at about 2100 LT at all heights for the diurnal component and at 0600 and 1800 LT at 85 km for the semidiurnal component. These results appear to be the first reported measurements of tidally induced vertical displacements in the mesopause region.
Linear prediction of sea ice anomalies
Authors: Johnson C. M. , Lemke P. , Barnett T. P.
Published: February 2008

Stationary and cyclostationary statistical models are developed to predict Arctic and Antarctic sea ice anomalies, using as predictors previous sea ice, atmospheric, and oceanic anomalies. A prediction model hierarchy is developed by using first internal (i.e., sea ice) predictors, including persistence, lateral advection, and diffusion, and a cyclostationary model that allows the prediction coefficients to vary seasonally. An external cyclostationary model hierarchy is developed next to investigate the ability of atmospheric winds, heat flux proxies air temperatures, and sea surface temperatures (SST's) to predict sea ice extent. In the Arctic the highest skill was generally achieved by the cyclostationary internal model. Attempts to forecast the ice data at 1–2 month intervals after removal of its autoregressive component, using external predictors, gave nonsignificant models. At longer lead times (e.g., 3 months) the SST in the North Pacific was superior to persistence for sea ice prediction in the western Bering Sea. In the Southern Ocean, especially off East Antarctica, the model that included lateral advection and diffusion outperformed both persistence and the cyclostationary internal model. In the Weddel Sea and the Ross Sea, persistence proved to be the best sea ice predictor. No external models were tested for Antarctic sea ice because of insufficient data.
Interpretation of ozone temperature correlations: 1. Theory
Authors: Rood Richard B. , Douglass Anne R.
Published: February 2008

Correlations between ozone and temperature are commonly used to investigate the photochemical and dynamical aspects of satellite‐derived ozone data. In this paper, the dynamical contributions to the ozone temperature correlations are examined using simple analytic and numerical models. It is shown that the phase differences between ozone and temperature waves caused by dynamical forcing can mimic the phase relationships predicted for photochemical equilibrium. Furthermore, the dynamical contribution to the phase relationship between ozone and temperature waves is routinely significant for chemistry time scales of ≃0.5 days and is potentially important for time scales as short as 2 hours during stratospheric warmings. The model results are highly relevant to the analysis of the limb infrared monitor of the stratosphere and solar backscatter ultraviolet data taken during the winter of 1979.
Accurate stratospheric particle size distributions from a flat plate collection surface
Authors: Zolensky Michael E. , Mackinnon Ian D. R.
Published: February 2008

The first representative chemical, structural, and morphological analysis of the solid particles from a single collection surface has been performed. This collection surface sampled the stratosphere between 17 and 19 km in altitude in the summer of 1981, and therefore before the 1982 eruptions of El Chichón. A particle collection surface was washed free of all particles with rinses of Freon and hexane, and the resulting wash was directed through a series of vertically stacked Nucleopore filters. The size cutoff for the solid particle collection process in the stratosphere is found to be considerably less than 1 μm. The total stratospheric number density of solid particles larger than 1 μm in diameter at the collection time is calculated to be about 2.7×10−1 particles per cubic meter, of which approximately 95% are smaller than 5 μm in diameter. Previous classification schemes are expanded to explicitly recognize low atomic number material. With the single exception of the calcium‐aluminum‐silicate (CAS) spheres all solid particle types show a logarithmic increase in number concentration with decreasing diameter. The aluminum‐rich particles are unique in showing bimodal size distributions. In addition, spheres constitute only a minor fraction of the aluminum‐rich material. About 2/3 of the particles examined were found to be shards of rhyolitic glass. This abundant volcanic material could not be correlated with any eruption plume known to have vented directly to the stratosphere. The micrometeorite number density calculated from this data set is 5×10−2 micrometeorites per cubic meter of air, an order of magnitude greater than the best previous estimate. At the collection altitude, the maximum collision frequency of solid particles >5 μm in average diameter is calculated to be 6.91×10−16 collisions per second, which indicates negligible contamination of extraterrestrial particles in the stratosphere by solid anthropogenic particles.
The interaction of a dipolar thunderstorm with its global electrical environment
Authors: Tzur I. , Roble R. G.
Published: February 2008

A two‐dimensional numerical model is used to calculate the electric field and current that flow from a dipolar thundercloud into the global electric circuit. The model domain includes a hemisphere in which the thundercloud acts, an equalization layer between 65 and 100 km, and a magnetic conjugate hemisphere. To maintain the measured fair‐weather electric field and ionospheric potential, the output current from the thunderstorm is assumed to flow into the finite volume of the atmosphere extending from the ground to 100 km. Our calculations show different patterns of current flow for equatorial and high‐latitude thunderclouds. When the geomagnetic field lines are vertical, the vertical current in the equalization layer above a thundercloud is more confined to flow in a relatively narrow current tube rather than spreading horizontally, as in the case of equatorial horizontal magnetic field lines. The total upward current above the model thunderstorm is 0.7 A. This vertical current is constant up to about 65 km, and then it decays by about 15%equalization layer, where it is redirected horizontally and then downward toward the ground. The altitude of this transition depends on the day and night ionospheric conditions and on the direction of the magnetic field lines. Above 65 km, in the magnetic conjugate hemisphere, there is a further horizontal spreading of the thunderstorm current. Below this altitude the spreading stops, and only vertical currents flow to the ground. Our results show that it is important to include a realistic model of the equalization layer with current flow to the magnetic conjugate hemisphere to evaluate the role of thunderstorm charging of the global circuit.
The June 22 tropical squall line observed during COPT 81 experiment: Electrical signature associated with dynamical structure and precipitation
Authors: Chauzy S. , Chong M. , Delannoy A. , Despiau S.
Published: February 2008

The tropical convection experiment COPT 81 (Convection Profonde Tropicale) was carried out near Korhogo (Northern Ivory Coast) during May and June 1981. The June 22 squall line was observed using meteorological and electrical equipment. The frontal part was characterized by a heavy precipitation core associated with strong convection. It was followed by a region of weak precipitation and a wide area of stratiform rain. The characteristic of this squall line resides in the two‐dimensional structure of the observed three‐dimensional wind fields, with intense convection ahead of the heavy precipitation core. Electrical measurements indicate that electrostatic field changes, at ground level, occurred in the weak precipitation zone and in the stratiform precipitation region. No particular electrical activity was observed in the most convective but shallow part of the squall line. A classical dipole structure appeared within the stratiform area. The stationary electrical structure was coherent with the stationary dynamics and precipitation pattern of the squall line.
The fine structure in the field change produced by positive ground strokes
Authors: Hojo Junichi , Ishii Masaru , Kawamura Tatsuo , Suzuki Fukumune , Funayama Ryunosuke
Published: February 2008

Several features of the field change waveforms originating from positive first return strokes in cloud‐to‐ground lightning flashes were clarified on the basis of observations of electric and magnetic field changes with bandwidths of 32 Hz to 1.2 MHz and 160 Hz to 1.2 MHz, respectively. In most positive waveforms, the rapidly rising portion (fast transition) was seen to follow the slowly rising portion (slow front), as is usually observed in the waveforms of negative return strokes. The average 10–90% rise times of field waveforms associated with positive first return strokes in Niigata, located in Japan's winter thunderstorm area, in winter and in Tokyo in summer were 8.7 and 6.7 μs, respectively. These values were about twice the 10–90% rise times for the negative first return strokes observed over the corresponding period in each area. Owing to the significantly longer slow front of positive waveforms, the average zero‐to‐peak rise time for the positive return strokes obtained from the same recordings was 22.3 μs, which is about 3 times larger than that for negative strokes: 7.5 μs. Only 1/3–1/4 of the waveforms of positive first return strokes observed in both summer and winter had discernible pulses preceding return stroke field change. The average time interval between leader pulses within a 100‐μs period just prior to the first return strokes observed in winter in Niigata was 17.4 μs, approximately equal to the reported value for negative first return strokes in Florida in summer.
Electromagnetic radiations from rocks
Authors: Ogawa Toshio , Oike Kazuo , Miura Taiji
Published: February 2008

To test the possibility of the emission of electromagnetic waves from rocks, experiments have been made to measure the electric field by using mainly granite samples that were struck together or struck by a hammer or a weight and were fractured by a bending moment. The wide‐band (10 Hz to 100 kHz) waveforms of electric signals were digitally recorded. Roughly four kinds of signals have been observed: 30 kHz, 5 kHz, 10 Hz and, in addition, intermittent pulses. Using these measurements of the electric fields, the average electric dipole moment generated was estimated to be 10−14 C m. The possibilities of producing such a dipole moment are discussed in terms of contact electrification (or separating electrification) and piezoelectrification, and both possibilities are shown.
Electrochemical concentration cell ozonesonde accuracy and precision
Authors: Barnes Robert A. , Bandy Alan R. , Torres Arnold L.
Published: February 2008

The accuracy and precision of electrochemical concentration cell ozonesondes using 1.5% KI sensing solution were measured as a function of pressure altitude from 800 to 6 mbar. Measurements were made in an environmental chamber designed to monitor the instruments' response while subjecting them to ozone, pressure, and temperature profiles typical of those encountered during balloon‐borne soundings. Data from dual‐instrument balloon soundings were used to provide an independent estimate of precision. The precision was found to be 6–10% (one standard deviation) from 800 to 200 mbar, 5–6% from 200 to 10 mbar, and thereafter increasing to 16% at 6 mbar. The accuracy profile indicated a 3–5% positive error from 300 to 50 mbar. Larger positive errors were observed from 800 to 300 mbar (8–14%) and from 50 to about 15 mbar (10%). The error curve then rapidly rolled off toward negative values, reaching −17% at 6 mbar. Use of new pumping efficiency measurement techniques should improve both accuracy and precision by 2–3% at the lowest pressures but would increase the accuracy error in the 50‐ to 15‐mbar range by about the same amount.
LIMS HNO3 data above 5 mbar: Corrections based on simultaneous observations of other species
Authors: Jackman Charles H. , Kaye Jack A. , Guthrie Paul D.
Published: February 2008

The LIMS HNO3 values are inconsistent with other LIMS measurements above about 5 mbar. During the four time periods analyzed, the LIMS HNO3 concentrations were much higher than the HNO3 concentrations computed using the other LIMS measurements (O3, H2O, NO2, and temperature). Until this inconsistency in the LIMS data is resolved, we recommend an alternative evaluation of upper‐stratospheric HNO3, consistent with all other LIMS measurements, for pressure levels less than 5 mbar. The alternate method of evaluating HNO3 makes use of a photochemical equilibrium approximation to derive OH from LIMS H2O and O3; this OH is used with LIMS NO2 to derive HNO3 above 5 mbar.
The response of ozone to solar proton events during solar cycle 21: The observations
Authors: McPeters R. D. , Jackman C. H.
Published: February 2008

We have analyzed ozone profile data from the solar backscattered ultraviolet instrument on NIMBUS 7 from 1979 to the present and have found clear cases of ozone destruction associated with five solar proton events (SPE's) of this solar cycle: on June 7, 1979, August 21, 1979, October 13–14, 1981, July 13, 1982, and December 8, 1982. During the SPE on July 13, 1982, the largest of this solar cycle, we observed no depletion at all at 45 km but a 15% ozone depletion at 50 km increasing to 28% depletion at 55 km, all at a solar zenith angle of 85°. We find that there is a strong variation of the observed depletion with solar zenith angle, with maximum depletion occurring at the largest zenith angles (near 85°) decreasing with distance from the terminator. The observed depletion in every case was short lived, disappearing within hours of the end of the SPE, suggesting that HOx reactions were responsible for the observed ozone depletion.
Comparison of band model calculations of upper atmospheric cooling rates for the 15‐micrometer carbon dioxide band
Authors: Boughner Robert E.
Published: February 2008

Comparisons are made between cooling rates for the CO2 15‐μm band in the middle to upper stratosphere (30–50 km) that were calculated by three widely used methods for handling infrared emission and absorption: an emissivity parameterization, a band absorptance formulation, and an “exact” line‐by‐line calculation. Cooling rates are presented for two temperature distributions—the U.S. Standard Atmospheric profile and a polar sounding. The band absorptance approach adopts Ramanathan's approximate treatment to account for transition of line shapes to Doppler broadening in the upper stratosphere but employs a new Doppler band model which yields better agreement with more detailed calculations. For both temperature profiles, cooling rates obtained by all three methods show good agreement with one another, differing by less than 0.5 K/day below 50 km. Above 50 km, variations among the cooling rates increase slightly to 0.5–1 K/day. At the stratopause, these differences correspond to a temperature error of 2 to 4 K.
Hemispheric interannual fluctuations in the distribution of atmospheric mass
Authors: Christy John R. , Trenberth Kevin E.
Published: February 2008

There is a substantial global redistribution of atmospheric mass associated with the mean annual cycle which results in large exchanges of mass between hemispheres. Interannual fluctuations in the distribution of mass both within each hemisphere and for the “hemispheric” mean over 17.5°–90° latitude are examined. The long‐period (1899–1980) historical sea level pressures over the northern hemisphere are analyzed and found to exhibit three modes of interannual zonal mean mass redistribution that are common to all seasons. The first is one where mass is mostly redistributed within the hemisphere, while the other two modes imply that compensation of mass occurs south of 17.5°N. A similar analysis over the southern hemisphere for 1972–1983 reveals remarkably similar results. Large and significant fluctuations in the hemispheric mean sea level pressure are found. These include record anomalies during the northern spring and summer of 1979, the year of the Global Weather Experiment. Opposite anomalies in the southern hemisphere, through the constraint of conservation of mass, imply the reality of a substantial global‐scale redistribution of atmospheric mass.
Decay of the sea ice in the North Water area: Observation of ice cover in Landsat imagery
Authors: Ito Hajime
Published: February 2008

The sea ice distribution in and around the North Water was observed by using satellite imagery obtained by Landsat. The observed data for 1973 were used to describe the decay of the ice cover in the area. The surface of the North Water did not seem to be open throughout the winter but rather to be mostly covered by a thin layer of pack ice. The entire decay began earlier in the spring because the ice present at the beginning of the decay period was relatively thin. The sea surface in the North Water lost ice cover earlier than the surrounding area. Open water was thus observed in spring when the ice cover at similar latitude was still complete. The mechanism of decay itself did not indicate any peculiarity.
Oxidant abundances in rainwater and the evolution of atmospheric oxygen
Authors: Kasting James F. , Holland Heinrich D. , Pinto Joseph P.
Published: February 2008

A one‐dimensional photochemical model has been used to estimate the flux of dissolved hydrogen peroxide (H2O2) and of other soluble species in rainwater as a function of atmospheric oxygen level. H2O2 should have replaced O2 as the dominant oxidant in rainwater at oxygen levels below 10−3–10−2 times the present atmospheric level (PAL). The exact value of pO2 at which H2O2 becomes more important than O2 depends on the abundance of trace gases such as CO, CH4, and NO. H2O2 was probably an important oxidant even in an O2‐free atmosphere, provided that CO2 levels were significantly higher than today's. In model atmospheres containing free O2 the concentration of photochemically produced oxidants generally exceeds that of photochemically produced reductants. The oxidizing power of rainwater is therefore greater than that due to dissolved molecular O2 alone. The difference is small at present but becomes important at O2 levels less than 10−3 PAL. At O2 levels between 10−4 and 10−5 PAL the oxidizing power of rainwater is almost independent of pO2. Precambrian soils in which a part or all of the Fe2+ in their source rocks has been oxidized to Fe3+ could therefore have developed in the presence of an atmosphere with very low values of pO2. On the other hand, the upper limit for pO2 during early and mid‐Precambrian time suggested by the incomplete oxidation of FeO in soils developed on basaltic rocks is affected only slightly by the presence of photochemical products in rainwater.
Channel reconstruction of triggered lightning flashes with bipolar currents from thunder measurements
Authors: Akiyama Hidenori , Ichino Kiyoshi , Horii Kenji
Published: February 2008

Two lightning flashes with bipolar currents were artificially triggered by small rockets during the winter of 1981 at Hokuriku in Japan. The lightning channels of two flashes are reconstructed by calculating both the cross‐power spectrum of thunder and the cross‐correlation function. The method of cross‐power spectrum is more effective in the case that the acoustic waves from different channel sections arrive at the microphone array at the same time. The thunder‐reconstructed channels coincide well with the actual channels under the cloud, which are reconstructed stereographically from two photographs. Charge distribution on the reconstructed channel and a sequence of discharge polarities are postulated according to the experimental results of discharge current, change of electric field at close range (70 m), surge voltage on a distribution test line at a distant of about 1 km, and framing photographs.
The subtropical mesospheric jet observed by the Nimbus 7 Limb Infrared Monitor of the Stratosphere
Authors: Dunkerton Timothy J. , Delisi Donald P.
Published: February 2008

Nimbus 7 Limb Infrared Monitor of the Stratosphere observations of wave‐mean flow interactions in the winter 1978–1979 middle atmosphere are surveyed, extending up to 0.05 mbar. These observations describe the evolution of the subtropical mesospheric jet and its polar mixed layer. Quasi‐steady mean wind patterns are disrupted by three transitions in this winter: one primarily affecting the mesosphere (December 15, 1978), a minor warming affecting both regions (January 26–February 8, 1979), and a major warming largely confined to the stratosphere (February 22, 1979). The zonally averaged flow is barotropically unstable in the wings of the subtropical mesospheric jet. All the major decelerations of the mean flow are correlated with DF, the body force per unit mass directly attributable to planetary Rossby waves, indicating that these waves make a significant contribution to the momentum budget in the lower half of the mesosphere.
Ground‐based nitric oxide measurements at Wallops Island, Virginia
Authors: Carroll Mary Anne , McFarland Mack , Ridley Brian A. , Albretton Daniel L.
Published: February 2008

In July of 1983, ambient measurements of nitric oxide (NO) were obtained at Wallops Island, Virginia, during the NASA GTE/CITE ground‐based instrument intercomparison field study. The instrument, which was designed for measurements in the remote troposphere from an aircraft platform, is briefly described. Ten days of ambient air observations showed broadly uniform diurnal behavior, although considerable variability was encountered. Two distinct synoptic meteorological conditions resulted in markedly different levels of nitric oxide abundance. When the local winds were from the north to west sectors, which placed the sampling site within 130 to 300 km of large urban centers, the midday mixing ratios were typically in the range of 200–300 pptv. In contrast, when the air mass sustained a 1‐ or 2‐day period over the Atlantic Ocean, the mixing ratios were substantially lower and in the 50–60 pptv range.
An intercomparison of carbon monoxide measurement techniques
Authors: Hoell J. M. , Gregory G. L. , McDougal D. S. , Sachse G. W. , Hill G. F. , Condon E. P. , Rasmussen R. A.
Published: February 2008

Results from an intercomparison of techniques to measure tropospheric levels of carbon monoxide (CO) are discussed. The intercomparison was conducted as part of the National Aeronautics and Space Administration's Global Tropospheric Experiment (GTE) and was held at Wallops Island, Virginia, in July 1983. Instruments intercompared included a laser differential absorption method and three grab sample/gas chromatograph methods. The intercomparison consisted of simultaneous measurements of ambient levels of CO and controlled injections of CO from a common manifold. Results from the techniques exhibited a high degree of correlation among themselves and with changes in the CO mixing ratio. The results suggested a level of agreement among the techniques of about 15%. However, a day‐to‐day bias between the techniques was observed, which resulted in differences between techniques as large as 38%.
Effects of dynamic heat fluxes on model climate sensitivity: Meridional sensible and latent heat fluxes
Authors: Gutowski W. J. , Wang W.‐C. , Stone Peter H.
Published: February 2008

We incorporate physically based parameterizations of atmospheric meridional heat fluxes into the climate model of Wang et al. (1984) to study their effects on climate changes caused by increases of CO2 abundance and solar constant variations. The physically based parameterizations calculate both the magnitudes and profiles of the sensible and latent heat fluxes in good agreement with observations. Comparisons of climate sensitivity between the physically based parameterizations and the original model's empirical parameterization for total transport are performed. The results indicate that both parameterizations yield about the same changes in global mean surface temperature and ice line, but the physically based parameterizations produce smaller changes in meridional temperature gradient. Also, the sensible and latent heat fluxes from the physical parameterization produce mutually compensating changes which are consistent with general circulation model results. We also study the separate feedback effects of sensible and latent heat fluxes by allowing only one or the other to change during climate changes. It is found that these variations in the partitioning of changes in the meridional heat transport have relatively small effects on the change of hemispheric mean surface temperature, but they can affect both the sign as well as the magnitude of the change of meridional temperature gradient. The change in total meridional heat transport is also relatively insensitive to the partitioning variations. Further analysis of the model's energy balance indicates that this insensitivity is a consequence of two features of the results: (1) absorption of the latitudinally varying part of the solar heating is affected very little by the partitioning, and (2) thermal structure changes that are affected by the partitioning do not influence greatly the zonal energy balance.
Concentrations and uncertainties of stratospheric trace species inferred from limb infrared monitor of the stratosphere data: 1. Methodology and application to OH and HO2
Authors: Kaye Jack A. , Jackman Charles H.
Published: February 2008

Zonally averaged limb infrared monitor of the stratosphere data from the Nimbus 7 satellite are used together with an essentially algebraic photochemical equilibrium model to infer concentrations of Ox, HOx, and NOx species over most of the stratosphere for the period from March 26, 1979 to April 1, 1979. Since the model is algebraic, sensitivity coefficients (logarithmic partial derivatives of inferred concentrations with respect to model input) may also be calculated. These are combined with estimates of the uncertainty in the model input parameters (concentrations, rate constants, photolysis rates) to give uncertainty factors for the inferred concentrations. Concentrations of OH and HO2 are calculated and found to compare reasonably well with previous measurements and two‐dimensional model calculations. Uncertainties are found, in general, to be largest in the lower stratosphere and to be greater for HO2 than they are for OH. The method of inference of OH concentration is found to have a great effect on the uncertainty factors calculated for HO2.
Inversion of limb radiance measurements: An operational algorithm
Authors: Bailey Paul L. , Gille John C.
Published: February 2008

The limb radiance inversion radiometer (LRIR) and limb infrared monitor of the stratosphere (LIMS) experiments aboard the Nimbus 6 and 7 spacecraft have made observations of infrared emission by CO2, O3, H2O, HNO3, and NO2 at the earth's limb. This paper describes a method by which such measurements can be inverted to give vertical distributions of temperature and mixing ratios as functions of pressure. The simple and efficient approach was successfully applied to the LRIR data and subsequently in the initial assessment of the LIMS data. Inversion of synthetic data indicates the size of the errors to be expected as a result of the assumptions and instrumental errors. Retrievals of measured LIMS radiances are shown as examples and compared to in situ observations. The differences are comparable to those obtained with the more complex retrieval scheme used to process the LIMS archival products. Some problems are noted.
Carbonyl sulfide concentrations in the surface waters and above the Pacific Ocean
Authors: Johnson James E. , Harrison Halstead
Published: February 2008

We measured the concentration of carbonyl sulfide (OCS) in the marine atmospheric boundary layer and in the surface layer of the equatorial and northern Pacific Ocean on two oceanographic cruises during May and June of 1982 and during March–May of 1983. Our measurements of the mean concentration of atmospheric OCS are 502 ± 21 parts per trillion (ppt) on the 1982 cruise and 511 ± 19 ppt on the 1983 cruise. We found surface water OCS concentrations to range upward from 0.3 STP nL L−1 to a few cases over 3.0 STP nL L−1. We estimate the global mean supersaturation ratio of OCS in seawater to range from 1.5 to 3.0, indicating a global source of OCS from the ocean of 0.2 to 0.4 Tg yr−1. We have made laboratory measurements of the dimensionless Henry's law coefficient of solubility H, the concentration of OCS in air divided by its concentration in 34.90 per mil salinity seawater. We found ln H = 12.722 ± 0.082 − (3,496 ± 24)/T, with no evidence for nonlinearities in the solubility at ambient atmospheric concentrations of OCS.
Air chemistry over the tropical forest of Guyana
Authors: Gregory G. L. , Harriss R. C. , Talbot R. W. , Rasmussen R. A. , Garstang M. , Andreae M. O. , Hinton R. R. , Browell E. V. , Beck S. M. , Sebacher D. I. , Khalil M. A. K. , Ferek R. J. , Harriss S. V.
Published: February 2008

The tropical forests of the world are hypothesized to be an important source and/or sink for a number of atmospheric gas and aerosol species. As part of the National Aeronautics and Space Administration's Global Tropospheric Experiment, an aircraft flight (June 27, 1984) was conducted over the wet tropical forest of Guyana for purposes of characterizing the forest boundary layer. Instrumentation onboard the NASA Electra aircraft included measurement systems for a variety of chemical species, including ozone, carbon monoxide, dimethylsulfide, nonmethane hydrocarbons, and aerosols. The data reported represent the first comprehensive characterization of the wet tropical forest boundary layer from an aircraft platform. The data indicate that the boundary layer is a source of carbon monoxide, isoprene, and dimethylsulfide as well as being a sink for ozone. Reported aerosol data, including number density, mass concentration, and composition, indicate an increased aerosol presence in the boundary layer relative to the overriding troposphere. From an analysis of the aerosol composition this increase is the result of direct emissions from the forest as well as from various photochemical processes. The data are discussed in terms of their significance in the understanding of the wet tropical forest boundary layer as a source or sink for various species important to tropospheric chemistry.
Trends in atmospheric temperature profiles
Authors: Oehlert Gary W.
Published: February 2008

Trends in atmospheric temperatures from 850 to 30 mbar are estimated, using radiosonde data from 1957 through 1979. These estimated trends are not significantly different from zero, but they do show a “greenhouse” type profile. Trends calculated with 1968 through 1979 data are compared with model estimates for the period 1971 through 1981. The major differences are that the data show more cooling between 200 and 100 mbar than the model predicts and less warming at 850 mbar than the model predicts.
Horizontal spectra of atmospheric tracers measured during the Global Atmospheric Sampling Program
Authors: Nastrom G. D. , Jasperson W. H. , Gage K. S.
Published: February 2008

Variance power spectra of potential temperature, ozone, carbon monoxide, and water vapor at airliner cruise altitudes are presented. These results are based on data collected aboard commercial airlines at cruise altitudes during the Global Atmospheric Sampling Program (GASP). The horizontal scales (wavelengths) resolved by these data extend from 2.6–2400 km for temperature, 10–2400 km for ozone, 150–3000 km for water vapor, and 300–2500 km for carbon monoxide. The results divide into two distinct regimes in most cases, with the transition found at 500‐ to 800‐km wavelength. The long wavelength regime of temperature behaves as predicted by geostrophic turbulence theory, but only some of the chemical tracer results fit this model. At scales less than 500–800 km, spectral shapes of all tracers follow an approximately −5/3 power law dependence on wave number. At scales less than about 100 km, tropospheric ozone spectra follow a −1 power law. Spectral amplitudes of potential temperature and ozone are larger in the stratosphere than in the troposphere, while spectral amplitudes of carbon monoxide and water vapor are larger in the troposphere. The horizontal fluctuations giving rise to these spectra apparently result from that component of a spectrum of quasi‐horizontal displacements which acts orthogonal to the background gradient of each tracer. Numerical checks support this hypothesis for each of the chemical tracers, assuming the tracers are horizontally stratified. Finally, it is found that the frequency distribution of ozone spectral magnitude at a given wave number is approximately lognormal.
Stratospheric conductivity variations over thunderstorms
Authors: Holzworth R. H. , Norville K. W. , Kintner P. M. , Powell S. P.
Published: February 2008

This paper reports the first in‐situ observation of variations in the electrical conductivity over thunderstorms at 26 km altitude. The vector electric field, positive and negative polar conductivity, and optical lightning power/flash were measured by payloads on superpressure balloons in the southern hemisphere in early 1984. We find that in 72% of the thunderstorm periods observed (or in 23 of 32 periods) there were clear cases of conductivity variations while the balloons were over the thunderstorms. We present examples from two separate balloons at widely separated dates and locations showing both daytime and nighttime events. The conductivity measurements are made with the relaxation technique, and the vector field measurements are based on the double Langmuir probe high‐impedance method. We find that the positive and negative conductivity measurements vary independently and have a different temporal profile than the dc electric field. The polar conductivity variations can exceed a factor of 2 at this altitude. In seven of the nine most intense thunderstorm events the total conductivity increased, while in only one of these nine events did it decrease (one event had no change). Implications of these observations for global current patterns are discussed.
Observations of mean winds and tides in the upper mesosphere during 1980–1984, using the Poker Flat, Alaska, MST radar as a meteor radar
Authors: Tetenbaum D. , Avery S. K. , Riddle A. C.
Published: February 2008

A postprocessing selection algorithm is used to determine the meteor echoes detected on the Poker Flat, Alaska, MST radar (65°N, 147°W) from a composite data base consisting of meteor and turbulence echoes. The echo distributions depend on the geometry of the antenna beams, the presence of strong turbulence echoes, average power transmitted, and the number of coherent averages used in the signal processing. Winds are derived from the meteor echoes and are used to compute monthly mean winds and tides in the upper mesosphere. These results are consistent with previous high‐latitude observations. Tidal amplitudes are largest in summer and weakest in winter. The tides exhibit large month‐to‐month variability, although the seasonal averages in 1983 are in agreement with those of 1984. The semidiurnal tide exhibits a dramatic phase shift of approximately 180° from October to November in both years. Results suggest future enhancement of the MST wind data can be achieved with real‐time meteor echo detection.
Response of middle atmosphere to short‐term solar ultraviolet variations: 1. Observations
Authors: Keating G. M. , Pitts M. C. , Brasseur G. , De Rudder A.
Published: February 2008

A series of studies were performed concerning the response of low‐latitude ozone and temperature in the stratosphere and mesosphere to short‐term solar ultraviolet variability associated with the rotation of the sun. The studies are based on Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) stratospheric ozone and temperature data, Nimbus 7 solar backscattered ultraviolet (SBUV) stratospheric ozone and 205‐nm solar ultraviolet data, Solar Mesosphere Explorer (SME) 1.27‐μm mesospheric O3 data, SME 121.6‐nm solar ultraviolet data, and Nimbus 7 Stratosphere and Mesosphere Sounder (SAMS) stratospheric and mesospheric temperature data. Using a longer temperature time series than has been used in the past for such studies, response times of temperature to solar UV variability in the stratosphere are found to be unexpectedly long (6 days at 2 mbar) and to become much shorter in the mesosphere (1 day at 0.01 mbar). Maximum sensitivity of temperature to solar variability (0.3 K/percent 205‐nm radiation) is found to occur near 70 km. The coupling of the temperature and ozone response to solar UV variability has been isolated by studying ozone responses with and without temperature effects. Temperature effects tend to increase rather than decrease the amplitude and to shift the response time of stratospheric ozone to solar variability to an earlier time. Using a longer ozone time series than has been used in the past for such studies, the stratospheric ozone response with no correction for temperature effects is found to be approximately a 0.4% increase at 3 mbar for a 1.0% increase in 205‐nm solar radiation. In the mesosphere a major systematic ozone decrease has been detected near 0.05 mbar (∼70 km), with increased solar Lyman α (121.6 nm) radiation (−0.14% ozone decrease for a 1% increase in solar Lyman α). This may be caused by solar Lyman α photodissociating H2O vapor producing HOx, with subsequent destruction of Ox. Higher in the mesosphere, where H2O mixing ratios should be much lower, ozone is found to increase with increasing solar UV. Observed responses of HNO3 and NO2 to solar UV variability are also briefly discussed. The theoretical response of middle atmosphere species and temperature to solar UV variability is discussed in detail in a companion paper (Brasseur et al., this issue).
Simultaneous field measurements of biogenic emissions of nitric oxide and nitrous oxide
Authors: Anderson Iris Cofman , Levine Joel S.
Published: February 2008

Seasonal and diurnal emissions of nitric oxide (NO) and nitrous oxide (N2O) from agricultural sites in Virginia and Colorado were simultaneously determined as a function of soil temperature, percent moisture, and exchangeable nitrate, nitrite, and ammonium concentrations. Nitric oxide fluxes at the Virginia site were significantly correlated (P < 0.01) with nitrate concentration, temperature, and percent moisture. At the Colorado site, NO fluxes were both positively and significantly correlated (P < 0.01) with temperature and moisture. Nitrous oxide emissions were only observed when percent moisture approached or exceeded field capacity of the soil. Nitric oxide emissions at the Virginia site were observed throughout the entire year with 76% of the annual flux produced between May and October and 24% between November and April. Wintertime fluxes of NO have not previously been reported in the literature. Annual NO emissions at the Virginia site ranged from 0.53 kg(N) ha−1 yr−1 from unfertilized land to 2.08 kg(N) ha−1 yr−1 from fertilized land. Of the 196.4 kg ha−1 of fertilizer added to the soil site being studied, 0.79% was lost as NO(N), and 1.2% was lost as N2O(N). A series of diurnal studies demonstrated that variations in NO flux throughout the day were correlated with changes in soil temperature. Nitric oxide was emitted over a broad range of soil moisture conditions, provided that percent moisture did not exceed field capacity of the soil. When field capacity was exceeded, NO fluxes declined whereas N2O emissions increased. Rewetting of dry soils at the Colorado site resulted in dramatic increases in emissions of both NO and N2O. Our data suggest that NO is produced primarily by nitrification in aerobic soils whereas N2O is formed by denitrification in an aerobic soils.