Earth's Troposphere Research Articles

Analytical models of Doppler data signatures

A primary indicator of the accuracy of orbit determination based on Doppler tracking is the graph of residuals vs time. Parameter errors in the orbit determination model produce characteristic signatures in the residuals plot. A systematic method of modeling the signature due to a parameter error by means of first and second partial derivative approximations is presented. Signatures due to errors in station location, solar pressure, relativistic clock, and the Earth's troposphere are compared with residual plots from a spacecraft mission, corresponding to the introduction of the same parametric error into orbit determination software. A comparison of postfit residuals with and without the introduction of known modeling errors demonstrates that some errors can be masked by apparent convergence, resulting in erroneous estimates.

Comment on “The roles of carbon dioxide and water vapour in warming and cooling the Earth's troposphere” J. Barrett, Spectrochim. Acta part A, 51 (3) (1995) 415

Comment on “The roles of carbon dioxide and water vapour in warming and cooling the Earth's troposphere” J. Barrett, Spectrochim. Acta part A, 51 (3) (1995) 415

Comment on “The roles of carbon dioxide and water vapour in warming and cooling the Earth's troposphere” J. Barrett, Spectrochim. Acta Part A, 51 (3) (1995) 415

Comment on “The roles of carbon dioxide and water vapour in warming and cooling the Earth's troposphere” J. Barrett, Spectrochim. Acta Part A, 51 (3) (1995) 415

The roles of carbon dioxide and water vapour in warming and cooling the earth's troposphere

The roles of carbon dioxide and water vapour in warming and cooling the earth's troposphere

Intercomparison of tropospheric OH and ancillary trace gas measurements at Fritz Peak Observatory, Colorado

The determination of the concentration of OH in the Earth's troposphere is of fundamental importance to an understanding of the chemistry of the lower atmosphere. Although many experiments to measure OH concentration have been performed in recent years, very few operate at sensitivities necesssary to measure the extremely low amount of OH in the clean troposphere (0.1–0.2 parts per trillion by volume at summertime local noon). This paper describes an informal intercomparison campaign held at Fritz Peak, Colorado, in summer 1991 to intercompare the OH concentrations determined from a spectroscopic instrument and an in situ chemical conversion instrument, both with sensitivities at or below 5×105 molecules cm−3. Ancillary measurements including those of O3, CO, NO, NO2, NOy, H2O, SO2, aerosols, solar flux, and meteorological parameters were also performed to test photochemical theories of OH formation. These measurements also provided a means for comparing air masses at the long path and in situ sites. The intercomparison was very successful with measured values of OH concentration in agreement within one standard error much of the time. OH concentrations were typically low, rarely above 4×106 cm−3, with only slow growth during the morning hours, indicating the possible presence of scavenger species. Model results suggest higher than measured OH concentrations or the presence of scavenger species.

Western boundary currents in the atmosphere of Mars

WESTERN boundary currents (WBCs) are an intensification of north–south flow adjacent to an eastward-facing meridional boundary. Although most familiar in the oceans (where the Gulf Stream is the best known example), WBCs also occur in the Earth's troposphere, the main example being the East African Jet1, which is thought to play an important role in the Asiatic monsoon. Here we identify boundary currents in a different geophysical context: a numerical simulation of the atmosphere of Mars. In our simulation, WBCs exist in association with significant cross-equatorial flow and the presence of equatorial martian topography, which has vertical scale far exceeding terrestrial relief2. The intensity and width of these currents depend on model parameters, notably the surface drag. From a comparison of our results with other martian models we suggest that WBCs have already been simulated, although they were not previously identified as such3. The available observational evidence appears to be consistent with the presence of martian WBCs, which may be important in the generation of global and great dust storms.

The measurement of tropospheric OH by long path absorption 1. Instrumentation

The determination of the concentration of OH in the Earth's troposphere is of fundamental importance to an understanding of the chemistry of the lower atmosphere. Many experiments to measure OH concentration have been performed in recent years; very few of these experiments have produced significant results. In particular, because of the extremely low amount of OH in the clean troposphere (several tenths parts per trillion by volume at summertime local noon), none of the experiments performed have attained the sensitivity limit necessary to test the photochemical theories of OH and its temporal behavior. Described here is an experiment utilizing a laser source and very high resolution ultraviolet absorption spectroscopy to measure the concentration of OH in a clean environment at a measured sensitivity limit of approximately 5 × 105 cm−3 (0.01 pptv) with an integration time of several minutes. This limit is substantially below predicted noontime OH concentrations and should be low enough to provide a rigorous test of photochemical theories of hydroxyl formation. This paper describes the instrumentation developed to make the measurements.

Stratospheric depletion of CO on Titan

A deep stratospheric depletion of CO is found in Titan's atmosphere comparing millimetric and infrared observations [Marten et al., 1988; Lutz et al., 1983]. We suggest that adsorption of CO on aerosols in the region of Titan's atmosphere where methane is expected to condense may change the vertical distribution of CO below ≈ 40 km. Aerosols slowly pervading through the methane condensation region could transport enough CO to generate the observed tropospheric enrichment provided the sticking coefficient ε (fraction of collisions yielding adsorption) is 6 10−4, assuming the same eddy diffusion coefficient K as in the Earth troposphere. In the case of a lower mixing rate, generally favoured, smaller values of ε are allowed (down to ≈ 10−6). Besides, the final radius of methane particles, just above the region where methane evaporates (below ≈ 10 km), must be 100 μm within a factor of 10. The hypothesis presented in this paper, if it is confirmed by laboratory measurements, could be an indirect evidence for large amounts of CH4 ice in the Titanian atmosphere.

Chemistry of Atmospheres: An Introdction to the Chemistry of the Atmospheres of Earth, the Planets, and Their Satellites

1. Chemical composition: a preliminary survey 2. Atmospheric behaviour as interpreted by physics 3. Photochemistry and kinetics applied to atmospheres 4. Ozone in Earth's stratosphere 5. The Earth's troposphere 6. Ions in the atmosphere 7. The airglow 8. Extraterrestrial atmospheres 9. Evolution and change in atmospheres and climates

Diurnal cycle of tropospheric OH

The hydroxyl free radical, OH, is sunlight's prime agent in maintaining the trace-gas composition of the Earth's troposphere, and at the same time serves as the catalyst responsible for many of the symptoms of urban and regional air pollution. We have used low-pressure fluorescence to measure the ambient concentration of this radical during two continuous 36-hour periods in early summer and late autumn, 1985. The summer and autumn maxima were 3 × l06 and 4 × l05 molecules cm−3 (10−13 and 2 × l0−14 relative to air), respectively. The observed concentrations lie within the rather large latitude of Current estimates based on trace-gas lifetimes or atmospheric photochemical models.

Tropospheric chemistry research

To answer basic science questions about man's influence on the Earth's troposphere and how to protect it, a National Research Council (NRC) panel has proposed a longterm international research program to study global tropospheric chemistry. The panel estimates that initial funding of $10–$20 million per year will be required, increasing yearly for the program's minimum 10‐year life.According to the panel, this proposed effort would be different from existing atmospheric chemistry programs, such as those concerning acid precipitation, for two reasons: First, the proposal calls for a long‐term effort, not a short‐term reaction to political pressures or, as noted by one member of the panel, “crisis response.” Second, the panel emphasized the global framework and international cooperation requested in the proposal. According to panel members, many existing studies are urban or regional in nature and do not have the scope required to gain an overall understanding of the complex troposphere. Existing programs are seen as a foundation for what is envisioned as an allencompassing program.

Baroclinic instabilities in Jupiter's zonal flow

The baroclinic stability of Jupiter's zonal flow is investigated using a model consisting of two continuously stratified fluid layers. The upper layer, containing a zonal shear flow and representing the Jovian cloudy regions above p ∼ 5 bars, is the same as Eady's (1949) model for the Earth. The lower layer has a relatively large but finite depth with a quiescent basic state, representing the deep Jovian fluid bulk below p ∼ 5 bars. Due to the presence of the lower layer, the linearized non-dimensional growth rates are drastically reduced from the O(1) growth rates of the original Early model. Only very long wavelengths relative to the upper fluid's radius of deformation L 1 are unstable. Eddy transports of heat are also reduced relative to estimates based on scaling arguments alone. Since the hydrostatic approximation for the lower-layer perturbation breaks down at great depths, a second model is presented in which energy propagates downward in an infinitely deep lower fluid obeying the full linearized fluid equations. In this model, the growth rates are again very small, but now all wavelengths are unstable with maximum growth rates occurring for wavelengths O(1) relative to L 1. These results illustrate the importance for the upper-layer meteorology of the interface boundary condition with the lower fluid, which is radically different from the rigid lower boundary of the Earth's troposphere.

Is CS2 a precursor for atmospheric COS?

THE stratospheric sulphate layer1 may play a major part in the Earth's global radiation budget2,3. Recent measurements4–6 indicated that carbonyl sulphide (COS) has an appreciable concentration, ranging from 0.3 to 0.5 p.p.b. in the Earth's troposphere. The gas is relatively inert7,8 in the troposphere and may therefore diffuse to the stratosphere where, through photolysis7–9, it may provide a major source of sulphate for the formation of the stratospheric sulphate layer. Thus, the origin of atmospheric COS is of particular interest in the stratospheric sulphur cycle. Kurylo10 suggested that the reaction of carbon disulphide (CS2) with OH might form COS as a reaction product. We investigate this possibility here through global COS budget analysis in the light of new atmospheric and laboratory measurements. Recent measurements showed that CS2 has a tropospheric concentration of around 0.1 p.p.b.5. The gas has previously been detected in seawater samples by Lovelock11.

GAMETAG program examines chemistry of the earth's troposphere

GAMETAG program examines chemistry of the earth's troposphere

Turbulence in planetary occultations: II. Effects on atmospheric profiles derived from Doppler measurements

Turbulence in planetary atmospheres leads to both fluctuating and systematic errors in atmospheric profiles derived from Doppler measurements during radio occultation. If the upper atmospheres of Venus and Jupiter are about as turbulent as the earth's troposphere, we deduce rms fractional errors in temperature and pressure of less than ∼ 10 −2 for the Mariner 10 and Pioneer 10/11 occultation experiments. Fractional systematic errors are typically of the order of 10 −6. These estimates depende rather weakly on quantities characterizing the atmosphere and the occultation, and it is conjectured that turbulence-induced errors in atmospheric profiles derived from Doppler measurements are always very small in the weak scattering limit

Refraction theories of radio wave propagation through the troposphere—A review

The paper presents an overall review of the literature on the subject of refraction theories of electromagnetic wave propagation through the earth's troposphere, with particular emphasis on the more recent work. Following a historical introduction to the subject, a qualitative discussion is given of the phenomenon of tropospheric refraction. The physical mechanisms of propagation associated with different types of refractive index profiles are discussed. The paper then proceeds to review the main features of the rather extensive theoretical techniques that have been employed in the past to study the phenomenon.

Carbon Monoxide on Jupiter and Implications for Atmospheric Convection

A study of the equilibrium and disequilibrium thermochemistry of the recently discovered carbon monoxide on Jupiter suggests that the presence of this gas in the visible atmosphere is a direct result of very rapid upward mixing from levels in the deep atmosphere where the temperature is about 1100°K and where carbon monoxide is thermodynamically much more stable. As a consequence the observed carbon monoxide mixing ratio is a sensitive function of the vertical eddy mixing coefficient. We infer a value for this latter coefficient which is about three to four orders of magnitude greater than that in the earth's troposphere. This result directly supports existing structural and dynamical theories implying very rapid convection in the deep Jovian atmosphere, driven by an internal heat source.

Carbon Monoxide on Jupiter and Implications for Atmospheric Convection

A study of the equilibrium and disequilibrium thermochemistry of the recently discovered carbon monoxide on Jupiter suggests that the presence of this gas in the visible atmosphere is a direct result of very rapid upward mixing from levels in the deep atmosphere where the temperature is about 1100 degrees K and where carbon monoxide is thermodynamically much more stable. As a consequence the observed carbon monoxide mixing ratio is a sensitive function of the vertical eddy mixing coefficient. We infer a value for this latter coefficient which is about three to four orders of magnitude greater than that in the earth's troposphere. This result directly supports existing structural and dynamical theories implying very rapid convection in the deep Jovian atmosphere, driven by an internal heat source.

Radiative Transfer Within the Earth's Troposphere and Stratosphere: A Simplified Radiative-Convective Model

A radiative transfer model of the troposphere and stratosphere is presented which includes both long-wave cooling and solar heating due to H2O, CO2 and O3 and has a simplified formulation which facilitates the inclusion of Doppler broadening, H2O continuum bands, hot and minor isotopic bands of CO2, and overlap of H2O bands with CO2 and O3 bands. The radiative model is used to develop an accurate radiative-convective model for studying the global surface temperature, stratospheric thermal structure and the net outgoing long-wave flux.

Concerning the fluctuation characteristics of the earth's troposphere

Concerning the fluctuation characteristics of the earth's troposphere