The oceans as source of cloud-forming nuclei

Summary The number and size of salt particles produced by the bursting of air bubbles in sea water has been measured. Bubbles of diameters varying between 1/2 and 2 mm each produced about 300 nuclei the sizes of which, under the electron microscope, were mainly between 0.1 and 0.5 diameter. They appeared to consist mainly of sodium chloride, the smallest ones containing only 10^–15 g of salt.These results, together with measurements of the size distribution of salt nuclei collected over the oceans in areas of spray formation, indicate that the total concentrations of salt nuclei over the oceans in winds of up to 15 m sec^–1 probably do not exceed 100 cm^–3. The corresponding rate of production of salt nuclei at the sea surface is estimated to be 1000 cm^–2 sec^–1. It is therefore inferred that sea spray contributes perhaps only one-fifth of the nuclei involved in cloud formation, the majority being the products of combustion, either natural or man-made.     

Relation between concentrations of giant chloride nuclei and exchange in the atmosphere

Summary In Northern Bohemia 33 research flights were made during which concentration of giant condensation chloride nuclei was measured up to a height of 3,500 m above the earth's surface. Chloride particles were determined by traces left by them in a sheet of gelatine with silver nitrate (Liesegang circles). The actual size of the particles was obtained by comparison of particles of a known size, falling in a sedimentation tube, with images in the sensitive sheet, and the result was adapted to the analysis of samples during the flight. For each level at which a sample was exposed the spectrum of the sizes of nuclei was determined. During the year the average concentration of the giant chloride nuclei at a height of 100 m above the earth was 7.3×10^–3 cm^–3. At greater heights concentration of the nuclei decreased successively, so that at 2,000 m it was only 0.3×10^–3 cm^–3 and above the level of 3,000 m the nuclei occurred sporadically, on the whole. Under the influence of atmospheric exchange the concentration of the nuclei in the boundary layer up to 1,000 m above the earth's surface changes considerably both during the day and during the year. The highest concentration occurs at a height of several hundred metres above the earth in the winter month, at the morning and evening hours, i.e. during a more stable temperature lapse rate. From the established concentrations of the nuclei relation between the turbulent diffusion coefficient and the height above the earth was determined. Its average value during the year increases up to a height of 300 to 400 m above the earth. Above this level it decreases roughly according to the relation ofKz ^–6/7. The exponent changes not only with temperature stratification (with the time of day and year), but also with the average wind speed. For sodium-chloride particles of 2.5 in diameter the maximum value of turbulent diffusion coefficient (at level of 400 m), reaches about 18×10³ cm² sec^–1 while the minimum value is about 5×10³ cm² sec^–1 (above 2,000 m).     

The effect of water on stress relaxation of faulted and unfaulted sandstone

A series of stress relaxation experiments have been carried out on faulted and intact Tennessee sandstone to explore the influence of pore water on strength at different strain rates. Temperatures employed were 20, 300 and 400°C, effective confining pressure was 1.5 kb and strain rates as low as 10^–10 sec^–1 were achieved. Most samples were prefaulted at 2.5 kb confining pressure and room temperature. This is thought to have secured a reproducible initial microstructure.The strength of the dry rock was almost totally insensitive to strain rate in the range 10^–4 to 10^–10 sec^–1. In contrast, the strength of the wet rock decreased rapidly with strain rate at rates less than 10^–6 sec^–1. Brittle fracture of the quartz grains which constitute this rock is the most characteristic mode of failure under the test conditions used.The experimental data are discussed in terms of the possible deformation rate controlling processes, and it is suggested that in the wet experiments at intermediate to high strain rates (10^–7 to 10^–4 sec^–1) the observed deformation rate is controlled by the kinetics of water assisted stress corrosion, whilst deformation at low strain rates (ca. 10^–9 sec^–1) is controlled by a pressure solution process.The results have implications for the rheology of fault rocks at depths of perhaps 10 to 15 km in sialic crust.     

Ionisations-Neutralisationsbilanz in derE-Schicht nach Angaben von der totalen Sonnenfinsternis am 15. Februar 1961

Zusammenfassung Es werden die Grundgleichungen der Ionisations-Neutralisationsbilanz in derE-Schicht präzisiert und auf die Notwendigkeit der Berücksichtigung des Einflusses der lokalen ionisierenden Strahlungsquellen auf der Sonnenscheibe, der dynamischen ionosphärischen Vorgängen und der Veränderungen des äquivalenten Rekombinationskoeffizienten hingewiesen. Ferner wird eine Methodik zur Bestimmung der charakteristischen Grössen der Ionisations-Rekombinationsbilanz (q _0m ,q _d, ) dargelegt. Zu dem Zweck werden die Messergebnisse aus der Periode der Sonnenfinsternis von zwei unweit voneinander gelegenen Ionosphärenstationen verwendet. Die Methodik wird auf die während der totalen Sonnenfinsternis am 15. Februar 1961 auf den Ionosphärenstationen in Sofia und Nesebar erhaltenen Ergebnisse angewandt. Für den Rekombinationskoeffizienten werden Werte zwischen 0,63·10^–7 cm³sec^–1 und 2,32·10^–7 cm³sec^–1 und für die Elektronenproduktion unter dem Einfluss der ionisierenden Strahlung von der homogenen Sonnenscheibeq _0m 1700 cm^–3sec^–1 erhalten.

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Summary The basic equations for the ionisation-neutralisation balance in theE layer have been shown the necessity to take in account the influence of the local ionisation sources on the disk of the sun, the dynamic ionospheric processes and the variations in the equivalent recombination coefficient. The method for determining the characteristic quantities of the ionisation-recombination balance (q _0m ,q _d, ) has been exhibited for this purpose are used measurement data from two ionospheric stations located not far from each other, in the period of the solar eclips on 15 February, 1961. The quantity of the recombination coefficient lay between 0.63×10^–7 sec^–1 cm³ and 2.32×10^–7 sec^–1 cm³; the electron production under the action of the ionising radiation of the homogen disk showsq _0m 1700 sec^–1 cm^–3.

     

On the reynolds stress and lateral eddy viscosity due to transient oceanic Rossby waves

Summary From numerical solutions of a wind-driven homogeneous ocean model, anegative lateral eddy viscosity of the order 10⁴ cm² sec^–1 is inferred from the large-scale time-dependent currents in the interior of an enclosed shallow basin. The transient Rossby waves in this region produce a systematic convergence of eddy momentum at the latitude of the maximum average eastward current, and thus effect a transfer of zonal momentum from the large-scale eddies to the mean flow. In this sense they are analogous to the Rossby waves in the atmospheric general circulation, and it is speculated that such waves may help to maintain the mean zonal ocean currents. Although this negative viscosity induced by the large-scale transients is relatively small compared with the prescribed lateral viscosity of 10⁸ cm² sec^–1 and should be given a quite different physical interpretation, it is evidently an important viscous effect for the mean flow in the interior of the basin. The prescribed viscosity, on the other hand, is effective in controlling the model's simulated sub-grid scale dissipation, which occurs almost entirely in the nearby steady boundary currents.     

The criterion of dynamic stability of zonal motion including the vertical shear

Summary Many writers treated on the problem of dynamic instability of westerly flow due to the excessive horizontal shear, and the present author discusses the corresponding dynamic instability due to the vertical shear. The critical vertical shear in indifferent stratification is given by the condition — the meridional component of absolute vorticity vanishes, — and is an approximate negative valueof 10^–4 sec ^–1 in middle latitude. However the critical vertical shear in normal stable stratification is a fairly large negative value of 2 sec^–1. It might be emphasized that the problem of this study differs fromRichardson's criterion of turbulence, for the present author discusses the condition under which the zonal flow is dynamically stable, whileRichardson expressed the condition under which the turbulence will decrease.     

Size distribution of airborne magnetic ‘back spherules’ in the 1–5 μ range

Summary Airborne particulate matter was sampled at Mt. Cimone, Italy, to determine the size distribution of black spherules in the 1–5 diameter range. The magnetic fraction of airborne particulate matter was separated by forcing air through a strong magnetic sampling device, where ferromagnetic particles accumulated on microscope slides.Sizes of the black spherules were determined by counting under a microscope. Samples were dissolved and analyzed for iron content. Distribution was found to be in agreement with that of deep-sea sediment and satellite high atmosphere samples. The rate of terrestrial accretion of cosmic matter composed of black spherules appears to be approximately 10^–15 g cm^–2 sec^–1.     

The relationship between vertical eddy diffusion and buoyancy gradient in the deep sea

Vertical eddy diffusivities (K_v's) have been estimated at fourteen widely separated locations from fourteen²²²Rn profiles and two²²⁸Ra profiles measured near the ocean floor as part of the Atlantic and Pacific GEOSECS programs. They show an inverse proportionality to the local buoyancy gradient [(g/?)(??_pot/?z)] calculated from hydrographic measurements. The negative of the constant of proportionality is the buoyancy flux [?K_v(g/?)(??_pot/?z)] which has a mean of ?4 × 10^?6 cm²/sec³. Our results suggest that the buoyancy flux varies very little near the ocean floor. K_v's for the interior of the deep Pacific calculated from the relationship K_v = (4 × 10^?6cm²/sec³)/[(g/?)(??_pot/?z)] agree well with published estimates. K_v's calculated for the pycnocline are one to two orders of magnitude smaller than upper limits estimated from tritium and⁷Be distributions.Heat fluxes calculated with the model K_v's obtained from the²²²Rn profiles average 31 μcal cm^?2 sec^?1 in the Atlantic Ocean and 8 μcal cm^?2 sec^?1 in the Pacific Ocean.     

Charge distribution on the atmospheric aerosol over the North Atlantic and the Indian Ocean

The distribution of electric charge on the marine aerosol was determined near the sea surface of the Indian Ocean and the North Atlantic during the final stage of the Snellius II-expedition. Mean values for small ion concentrationsn ⁺=455 cm^–3 andn ^–=340 cm^–3 were found over the Atlantic, whilen ⁺=310 andn ^–=250 cm^–3 were the mean values over the Indian Ocean. The ration ⁺/n^– increased from 1.2 to 2.0 with decreasing wind velocity. At wind velocities below 5 m/s 75% of the net space charge near the ocean surface was found to be carried by small ions.     

Recombination rates of small ions and their attachment to aerosol particles

It could be shown by measurements of the air conductivity and using a mean profile for the ionization rate that experimental and theoretical values of the recombination rate of small ions based on a three body recombination process (Thomson) are in very good agreement up to 20 km altitude. The divergency of the experimental and theoretical curves above 20 km can be interpreted by assuming that there exists in this altitude region a crossover from the three body recombination to a two body recombination process. The value of the recombination coefficient is about 4·10^–7 cm³ s^–1 in 25 km altitude, compared with 1.4·10^–6 cm³ s^–1 at ground level. Furtheron it was possible for the first time to get some experimental data of attachment coefficients up to 13 km from simultaneous measurements of the air conductivity and Aitken nuclei concentration. These values are in good agreement with those obtained by theoretical considerations.     

A determination of the wind-driven ocean circulation from the vorticity budget of the atmosphere

Summary The annual mean distribution of the surface stress curl over the Northern Hemisphere has been estimated from the horizontal vorticity advection in the atmosphere by using the upper-wind statistics as published byCrutcher [2]³). The results are used to compute the wind-driven mass transport (Sverdrup transport) in North Atlantic and North Pacific. The calculated intensity of the Gulf Stream is largest at the latitude 35°N, where a mass transport of 45×10⁶ tons sec^–1 is obtained; for the maximum intensity of the Kuroshio current a value of 60×10⁶ tons sec^–1 is obtained.Research supported in part by the Section of Atmospheric Sciences, National Science Foundation, Grant GP-2561.The research for this study was started by the author at the Department of Meteorology and Oceanography, The University of Michigan, Ann Arbor, Mich.     

New terrestrial heat flow values from Hungary

Summary Temperature and conductivity measurements show, that in the Southern part of Transdanubia (the part of Hungary which lies Westwards from Danube) the heat flow is about 2–2.4·10^–6 cal/cm² sec. Eastward from the Danube, in the Hungarian Plain estimates are even higher, and vary between 2.3·10^–6 and 2.8·10^–6 cgs. The gradient of temperature is everywhere quite high, 5.0 resp. 5.8·10^–4 deg. C/cm on the average. Thus, at a depth of 1000 m, the virgin rock temperature is about 60–70 deg. C, at 2000 m about 110–130 deg. C.     

The effect of light on the release of organic compounds by the cyanobacteriumOscillatoria rubescens

The effect of light intensity on the release of dissolved organic carbon during photosynthesis on NaH¹⁴CO₃ was investigated using the phytoplanktonic CyanobacteriumOscillatoria rubescens. The released products were fractionated by molecular size and chemical identifications attempted using combined thin-layer electrophoresis and chromatography, and high pressure liquid chromatography.Within the range of irradiances tested (from 6 to 60 µmole m^–2 sec^–1), though the upper one inhibited photosynthesis ofO. rubescens, light had little effect on the quantity and composition of the excreted products. The released carbon was always lower than 3% of the incorporated carbon, and mainly composed (62 to 86%) by small molecular weight compounds. The prevailing identified compounds were amino acids which represented more than 20% of the excreted carbon. Among organic acids, glycolic acid accounted for less than 2% of the recovered radioactivity. Glucose was the only identified sugar.Abbreviations EOC excreted organic carbon - DOC dissolved organic carbon - PER percent extracellular release - LMW low molecular weight - HMW high molecular weight - AA amino acids - µmoles m^–2 sec^–1 = µEinsteins m^–2 sec^–1     

Effect of displacement rate on the real area of contact and temperatures generated during frictional sliding of Tennessee sandstone

Summary The real area of contact has been determined, and measurements of the maximum and average surface temperatures generated during frictional sliding along precut surfaces in Tennessee sand-stone have been made, through the use of thermodyes. Triaxial tests have been made at 50 MPa confining pressure and constant displacement rates of 10^–2 to 10^–6 cm/sec, and displacements up to 0.4 om. At 0.2 cm of stable sliding, the maximum temperature decreases with decreasing nominal displacement rate from between 1150° to 1175°C at 10^–2 cm/sec to between 75° to 115°C at 10^–3 cm/sec. The average temperature of the surface is between 75 and 115°C at 10^–2 cm/sec, but shows no rise from room temperature at 10^–3 cm/sec. At 0.4 cm displacement, and in the stick-slip mode, as the nominal displacement rate decreases from 10^–3 to 10^–6 cm/sec, the maximum temperature decreases from between 1120° to 1150°C to between 1040° to 1065°C. The average surface temperature is 115° to 135°C at displacement rates from 2.6×10^–3 to 10^–4 cm/sec.With a decrease in the displacement rate from 10^–2 to 10^–6 cm/sec, the real area of contact increases from about 5 to 14 percent of the apparent area; the avergge area of asperity contact increases from 2.5 to 7.5×10^–4 cm². Although fracture is the dominate mechanism during stick-up thermal softening and creep may also contribute to the unstable sliding process.     

Contributions of H2S to the atmospheric sulfur cycle

H₂S is a most important biogenic sulfur compound with regard to the atmospheric sulfur cycle. Our present knowledge of the spatial and temporal distribution of this trace gas is rather incomplete owing to unreliable analytical methods. Therefore, a new method for the analysis of H₂S in the g-range was applied. This paper deals with the results of ground- and aircraft measurements of H₂S in unpolluted air over swamps and tidal flats. Based on the measured vertical distributions a removal coefficient of 2.3×10^–5 sec^–1 and an average lifetime of 12 hours were calculated. Some conclusions of the contribution of H₂S to the atmospheric sulfur budget are added.     

An investigation of the size frequency resolution of an aerosol by the static method of diffusion

Summary Theoretical considerations are put forward for identifying the Dynamic and Static Methods of Diffusion measurements of aerosol particles. On the basic of this equality the Exhaustion Method of Diffusion developed byPollak andMetnieks for the size-frequency resolution of a heterogeneous aerosol by Dynamic Diffusion Methods should be applicable to Static Methods. This hypothesis is tested using a Pollak-Nolan nucleus counter as decay vessel. It is shown that turbulence in the counter is the most serious obstacle against this type of approach to finding the size components of an aerosol. The time involved, the high humidity in the counter and a hypothetical nucleus-free zone are other major difficulties for relatively large Aitken nuclei. It is established, however, that for particles whose diffusion coefficient is of the order of 10^–3 cm² sec^–1, the proposed method should be quite workable.     

The eruptive history of the Tequila volcanic field, western Mexico: ages, volumes, and relative proportions of lava types

The eruptive history of the Tequila volcanic field (1600 km²) in the western Trans-Mexican Volcanic Belt is based on ⁴⁰Ar/³⁹Ar chronology and volume estimates for eruptive units younger than 1 Ma. Ages are reported for 49 volcanic units, including Volcán Tequila (an andesitic stratovolcano) and peripheral domes, flows, and scoria cones. Volumes of volcanic units 1 Ma were obtained with the aid of field mapping, ortho aerial photographs, digital elevation models (DEMs), and ArcGIS software. Between 1120 and 200 kyrs ago, a bimodal distribution of rhyolite (~35 km³) and high-Ti basalt (~39 km³) dominated the volcanic field. Between 685 and 225 kyrs ago, less than 3 km³ of andesite and dacite erupted from more than 15 isolated vents; these lavas are crystal-poor and show little evidence of storage in an upper crustal chamber. Approximately 200 kyr ago, ~31 km³ of andesite erupted to form the stratocone of Volcán Tequila. The phenocryst assemblage of these lavas suggests storage within a chamber at ~2–3 km depth. After a hiatus of ~110 kyrs, ~15 km³ of andesite erupted along the W and SE flanks of Volcán Tequila at ~90 ka, most likely from a second, discrete magma chamber located at ~5–6 km depth. The youngest volcanic feature (~60 ka) is the small andesitic volcano Cerro Tomasillo (~2 km³). Over the last 1 Myr, a total of 128±22 km³ of lava erupted in the Tequila volcanic field, leading to an average eruption rate of ~0.13 km³/kyr. This volume erupted over ~1600 km², leading to an average lava accumulation rate of ~8 cm/kyr. The relative proportions of lava types are ~22–43% basalt, ~0.4–1% basaltic andesite, ~29–54% andesite, ~2–3% dacite, and ~18–40% rhyolite. On the basis of eruptive sequence, proportions of lava types, phenocryst assemblages, textures, and chemical composition, the lavas do not reflect the differentiation of a single (or only a few) parental liquids in a long-lived magma chamber. The rhyolites are geochemically diverse and were likely formed by episodic partial melting of upper crustal rocks in response to emplacement of basalts. There are no examples of mingled rhyolitic and basaltic magmas. Whatever mechanism is invoked to explain the generation of andesite at the Tequila volcanic field, it must be consistent with a dominantly bimodal distribution of high-Ti basalt and rhyolite for an 800 kyr interval beginning ~1 Ma, which abruptly switched to punctuated bursts of predominantly andesitic volcanism over the last 200 kyrs.Electronic Supplementary Material Supplementary material is available in the online version of this article at Editorial responsility: J. Donnelly-NolanThis revised version was published online in January 2005 with corrections to Tables 1 and 3.An erratum to this article can be found at     

Stratospheric aerosol inferred from electrical conductivity during a volcanically quiescent period

Profiles of electrical conductivity in the troposphere and stratosphere were measured by balloon-borne conductivity sondes at Garmisch-Partenkirchen, West Germany, from January to May, 1980, when volcanic activity was low. The aerosol concentration has been deduced from the relative decrease of conductivity from surrounding values by assuming the effective attachment coefficient of ions to aerosols. A prominent decrease of the conductivity near the tropopause is usually observed indicating high concentrations of Aitken particles (500–1000 cm^–3). A decrease of conductivity, well above the tropopause, is sometimes observed, probably due to the transport of tropospheric Aitken particles with high concentration (200–400 cm^–3) into the stratosphere.     

Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

This study compares the OV1-10 satellite measurements of the integral airglow intensities at 630 nm in the SAR arc regions observed in the northern and southern hemisphere as a conjugate phenomenon, with the model results obtained using the time-dependent one-dimensional mathematical model of the Earth ionosphere and plasmasphere (the IZMIRAN model) during the geomagnetic storm of the period 15–17 February 1967. The major enhancements to the IZMIRAN model developed in this study are the inclusion of He+ ions (three major ions: O⁺ H⁺ and He⁺ and three ion temperatures), the updated photochemistry and energy balance equations for ions and electrons, the diffusion of NO⁺ and O⁺₂ ions and O(¹D) and the revised electron cooling rates arising from their collisions with unexcited N₂, O₂ molecules and N₂ molecules at the first vibrational level. The updated model includes the option to use the models of the Boltzmann or non-Boltzmann distributions of vibrationally excited molecular nitrogen. Deviations from the Boltzmann distribution for the first five vibrational levels of N₂ were calculated. The calculated distribution is highly non-Boltzmann at vibrational levels v > 2 and leads to a decrease in the calculated electron density and integral intensity at 630 nm in the northern and southern hemispheres in comparison with the electron density and integral intensity calculated using the Boltzmann vibrational distribution of N₂. It is found that the intensity at 630 nm is very sensitive to the oxygen number densities. Good agreement between the modeled and measured intensities is obtained provided that at all altitudes of the southern hemisphere a reduction of about factor 1.35 in MSIS-86 atomic oxygen densities is included in the IZMIRAN model with the non-Boltzm-ann vibrational distribution of N². The effect of using of the O(¹D) diffusion results in the decrease of 4–6% in the calculated integral intensity of the northern hemisphere and 7–13% in the calculated integral intensity of the southern hemisphere. It is found that the modeled intensities of the southern hemisphere are more sensitive to the assumed values of the rate coefficients of O⁺(⁴S) ions with vibrationally excited nitrogen molecules and quenching of O⁺(²D) by atomic oxygen than the modeled intensities of the northern hemisphere.     

Comparison of model electron densities and temperatures with Millstone Hill observations during undisturbed periods and the geomagnetic storms of 16–23 March and 6–12 April 1990

Measurements of F-region electron density and temperature at Millstone Hill are compared with results from the IZMIRAN time-dependent mathematical model of the Earths ionosphere and plasmasphere during the periods 16–23 March and 6–12 April 1990. Each of these two periods included geomagnetically quiet intervals followed by major storms. Satisfactory agreement between the model and the data is obtained during the quiet intervals, provided that the recombination rate of O⁺(⁴S) ions was decreased by a factor of 1.5 at all altitudes during the nighttime periods 17–18 March, 19–20 March, 6–8 April and 8–9 April in order to increase the NmF2 at night better to match observations. Good model/data agreement is also obtained during the storm periods when vibrationally excited N₂ brings about factor-of-2-4 reductions in daytime NmF2. Model calculations are carried out using different expressions for the O⁺ – O collision frequency for momentum transfer, and the best agreement between the electron-density measurements and the model results is obtained when the CEDAR interim standard formula for the O⁺ – O collision frequency is used. Deviations from the Boltzmann distribution for the first five vibrational levels of NI were calculated. The calculated distribution is highly non-Boltzmann at vibrational levels j > 2, and the Boltzmann distribution assumption results in the increase of 10–30% in calculated NmF2 during the storm-time periods. During the March storm at solar maximum the model results obtained using the EUVAC solar flux model agree a little better with the observations in comparison with the EUV94 solar flux model. For the April storm period of moderate solar activity the EUV94X model results agree better with the observations in comparison to the EUVAC model.