It has been suggested (Lindzen, 1967, 1968a, b; Lindzen and Blake, 1971; Hodges, 1969) that turbulence in the upper mesosphere arises from the unstable breakdown of tides and gravity waves. Crudely speaking, it was expected that sufficient turbulence would be generated to prevent the growth of wave amplitude with height (roughly as (basic pressure)−1/2). This work has been extended to allow for the generation of turbulence by smaller amplitude waves, the effects of mean winds on the waves, and the effects of the waves on the mean momentum budget. The effects of mean winds, while of relatively small importance for tides, are crucial for internal gravity waves originating in the troposphere. Winds in the troposphere and stratosphere sharply limit the phase speeds of waves capable of reaching the upper mesosphere. In addition, the existence of critical levels in the mesosphere significantly limits the ability of gravity waves to generate turbulence, while the breakdown of gravity waves contributes to the development of critical levels. The results of the present study suggest that at middle latitudes in winter, eddy coefficients may peak at relatively low altitudes (50 km) and at higher altitudes in summer and during sudden warmings (70–80 km), and decrease with height rather sharply above these levels. Rocket observations are used to estimate momentum deposition by gravity waves. Accelerations of about 100 m/s/day are suggested. Such accelerations are entirely capable of producing the warm winter and cold summer mesopauses.

http://climateknowledge.org/figures/Rood_Climate_Change_AOSS480_Documents/QC114_Lindzen_Gravity_Wave_Stress_JGR_1981.pdf

Turbulence and stress owing to gravity wave and tidal breakdown

The MSIS-86 empirical model of thermospheric temperature, density and composition uses new temperature and composition data from the Dynamics Explorer satellite to improve the representation of polar region morphology over that in the MSIS-83 model. Terms were added or changed to better represent seasonal variations in the polar regions under both quiet and magnetically disturbed conditions. Local time variations in the magnetic activity effect were added. In addition a new species, atomic nitrogen, was added to the previous list of N2, O2, He, O, H, and Ar covered by the model.

MSIS‐86 Thermospheric Model

Publisher Summary This chapter focuses on the uses of isotopes to understand water chemistry.I Isotopic compositions generally cannot be interpreted successfully in the absence of other chemical and hydrologic data. The chapter focusses on uses of isotopes in tracing sources and cycling of nitrogen in the water-component of forested catchment, and on dissolved nitrate in shallow waters, nutrient uptake studies in agricultural areas, large-scale tracer experiments, groundwater contamination studies, food-web investigations, and uses of compound-specific stable isotope techniques. Shallow waters moving along a flowpath through a relatively uniform material and reacting with minerals probably do not achieve equilibrium but gradually approach some steady-state composition. The chapter also discusses the use of isotopic techniques to assess impacts of changes in land-management practices and land use on water quality. The analysis of individual molecular components for isotopic composition has much potential as a method for tracing the source, biogeochemistry, and degradation of organic liquids and gases because different materials have characteristic isotope spectrums or biomarkers.

Tracing nitrogen sources and cycling in catchments

The vapour pressures of ice and supercooled water are reviewed with an emphasis on atmospheric applications. Parametrizations are given for the vapour pressure, molar heat capacity, and latent heat of vaporization of both ice and liquid water. For ice, the experimental vapour pressure data are in agreement with a derivation from the Clapeyron equation. Below 200 K cubic ice may affect the vapour pressure of ice both in the atmosphere and in the laboratory. All of the commonly used parametrizations for the vapour pressure of supercooled water are extrapolations that were not originally intended for use below the freezing point. In addition, the World Meteorological Organization definition of the vapour pressure of supercooled water contains an easily overlooked typographical error. Recent data on the molar heat capacity of supercooled water are used to derive its vapour pressure. Nevertheless, the uncertainty is such that measurements of the deliquescence and freezing behaviour of aerosol particles are beginning to be limited by uncertainties in the thermodynamics of supercooled water. Copyright © 2005 Royal Meteorological Society

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Review of the vapour pressures of ice and supercooled water for atmospheric applications

Nitrate (NO3 ) concentrations in public water supplies have risen above acceptable levels in many areas of the world, largely as a result of overuse of fertilizers and contamination by human and animal waste. The World Health Organization and the U.S. Environmental Protection Agency have set a limit of 10 mg L nitrate (as N) for drinking water because nitrate poses a health risk, especially for children, who can contract methemoglobinemia (blue-baby syndrome). Nitrate in lower concentrations is non-toxic, but the risks from long-term exposure are unknown, although nitrate is a suspected carcinogen. High concentrations of nitrate in rivers, lakes, and coastal areas can cause eutrophication, often followed by fi sh-kills, due to oxygen depletion. Increased atmospheric loads of anthropogenic nitric and sulfuric acids have caused many sensitive, low-alkalinity streams in North America and Europe to become acidifi ed. Still more streams that are not yet chronically acidic could undergo acidic episodes in response to large rain storms and/or spring snowmelt, seriously damaging sensitive local ecosystems. Future climate changes may exacerbate the situation by affecting biogeochemical controls on the transport of water, nutrients, and other materials from land to freshwater ecosystems. The development of effective management practices to preserve water quality, and remediation plans for sites that are already polluted, requires the identifi cation of actual N sources and an understanding of the processes affecting local nitrate concentrations. In particular, a better understanding of hydrologic fl owpaths and solute sources is required to determine the potential impact of contaminants on water supplies. Determination of the relation between nitrate concentrations in groundwater and surface water and the quantity of nitrate introduced from a particular source is complicated by:

Tracing Anthropogenic Inputs of Nitrogen to Ecosystems

The Giotto space probe's neutral mass spectrometer experiment has determined the abundances and the chemical, elemental and isotopic compositions of gases and low energy ions in the coma of comet Halley. Preliminary results show water predominating, at about 80 percent by volume, with a density of 4.7 x 10 to the 7th molecules/cu cm at 1000 km and a photodestruction scale length of 39,000 km. Limits on the abundances of CO2, NH3 and CH4 relative to H2O are also obtained. An ion temperature change observation indicates a contact surface location at 47,000 + or - 200 km.

In situ gas and ion measurements at comet Halley

Six rate coefficients of relative ozone formation contradict the role of molecular symmetry in the process that results in the enrichment of heavy ozone isotopomers. The results show that collisions between light atoms, such as 16O, and heavy molecules, such as 34O2 and 36O2, have a rate coefficient advantage of about 25 and 50 percent, respectively, over collisions involving heavy atoms and light molecules. These results suggest that the observed isotope effect for each isotopomer may be caused by the preponderance of a single reaction channel and not through molecular symmetry selection.

https://science.sciencemag.org/content/sci/283/5400/370.full.pdf

Ozone isotope enrichment: isotopomer-specific rate coefficients

Tropospheric ozone samples collected during a twelve-month period in urban air show an enrichment of about 9% in the heavy isotope 50O3 consistent with predictions from laboratory measurements. The enhancement of about 7% observed in 49O3 is still within the uncertainty of the expected value. These measurements confirm that the isotope effect, repeatedly found in laboratory experiments, is also produced in the atmosphere during the ozone formation process.

Measurement of heavy isotope enrichment in tropospheric ozone

A preliminary evaluation of the mass 28 amu/e signal observed in the neutral mode of the Giotto neutral gas mass spectrometer (NMS) is presented. At 1000 km from the nucleus we obtain for the CO number density n (CO)/n (H2O)≦0.07. The production rate of CO as a parent molecule directly from the nucleus is thus less than 7% of the H2O production rate. However, CO is also produced from an extended source in the inner coma (R < 20 000 km) and at 20 000 km from the nucleus we obtain for the total equivalent CO production rate 0.05≦Q (CO)/Q (H2O)≦0.15. For N2 an upper limit Q (N2)/Q (H2O)≦0.1 is derived. No parent molecule for the CO could be identified which would be in agreement with the NMS measurements. It is proposed that CO or a very short-lived parent is relased in the coma from cometary dust grains, such as the “CHON” particles.

The CO and N2 abundance in comet P/Halley

The oxygen isotope anomaly in ozone was first identified in isotopomers 49O3 and 50O3 with enrichments of over 10%. Recent rate coefficient measurements imply a new interpretation of the anomaly. The large variability of the rate coefficients of ozone formation O + O2
→ O3 of about 50% characterizes the ozone isotope effect and demonstrates its kinetic origin. Surprisingly, the rate coefficients correlate with the zero-point energy change of the oxygen molecules participating in the isotope exchange reactions but not with the mass of the ozone molecules. Rate coefficients of symmetric molecules depart from this linear relationship by about 20%.

Dieter Krankowsky

Papers

In situ gas and ion measurements at comet Halley

Ozone isotope enrichment: isotopomer-specific rate coefficients

Measurement of heavy isotope enrichment in tropospheric ozone

The CO and N2 abundance in comet P/Halley

Kinetic origin of the ozone isotope effect: a critical analysis of enrichments and rate coefficients