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.     

On sea-salt nuclei in the atmosphere

Summary The residues of cloud droplets collected at the summit of a mountain were examined with an electron microscope and their materials were identified with the aid of micro-electron-diffraction method. About 30% of nuclei of cloud droplets larger than 5 in radius were mainly composed of sodium chloride and their masses were 10^–1210^–13 gr. We also found salt particles in snow crystals. Some discussions are made about the process of the capture of these particles by snow crystals.     

The monzogabbroic intrusion in the island of Vulcano,Aeolian Archipelago,Italy

Two drill-holes were carried out during 1983–84 by the Joint Venture AGIP-EMS-ENEL on the island of Vulcano southwest of the Cratere della Fossa. After passing through pyroclastics and lavas of the young volcanic centres of Vulcano the drill-holes penetrated an intrusion of monzogabbro to leuco-monzogabbro composition. In one of the holes the top of the intrusion occurs at 1360 m and the intrusive rocks are found to the bottom of the well at 2050 m. At this depth the temperature exceeds 419 °C and the temperature gradients are sufficiently steep that magma could well be reached only a few hundred metres deeper. Lava of the South Vulcano centre is metamorphosed by the intrusion.A massive pyroclastic bed, underlying the welded scoriae deposits associated with collapse of the Caldera del Piano system, contains blocks of the intrusion. Radiometric data suggest an intrusion age of 30 000 years. Geophysical data indicate that the main intrusion is a shallow level and is located in the stretch of sea west of Mt. Lentìa.     

On some measurements of the condensation of different vapors upon Aitken condensation nuclei

No final theory on the activity of Aitken nuclei has been established yet. In particular the supersaturation is not known for the Aitken nuclei to grow into droplets, f.e. according toF. Volz only nuclei of radius >0.1 can cause condensation under atmospheric conditions. On the other hand according toH. G. Müller condensation over the continents has to occur at the Aitken nuclei since precipitation washes out the other nuclei.This uncertainty becomes obvious in the interpretation of the experimental results.Chr. Junge found that the necessary activation supersaturation of a continental Aitken aerosol and of artificial aerosols of the same size of nuclei lies between 2 and 20%, 10% being sufficient for the main fraction of nuclei to grow.In contrastW. Wieland was able to activate in a mixing cloud chamber a big portion, if not all, of the nuclei of a continental aerosol at supersaturations below 1.5%. Some of our own results, obtained with the same technic, agree with this. At supersaturations below 0.8% at least half of the Aitken nuclei present are activated. To obtain the same result with benzene and acetone we found, that benzene required a slightly smaller, and acetone a somewhat bigger supersaturation.However later experiments revealed a considerable effect of the geometry of the mixing cloud chamber upon the results. Since the physics of the chamber has not been fully explored the method was abandoned. Instead the principle of cooling by adiabatic expansion was used. An expansion apparatus based on the principle of a fotoelectric nucleus counter was developed allowing us to measure with two cathode ray oscillographs the pressure and simultaneously the change of intensity of a lightbeam due to the scattering on the forming cloud as a function of time. The length of the lightbeam could be chosen between 60 and 200 cm. The overpressure before the expansion was always 180 mm of mercury. The ratio of expansion rates was 12.53060 at the beginning of the expansion. The slowest rate was about 6 seconds, corresponding to a rate of ascent of 210 m/s at the beginning of the expansion. Smaller rates could not be obtained because of heat transfer at the chamber walls.The present work has been performed for the Eidgenössische Kommission zum Studium der Hagelbildung und der Hagelabwehr (Switzerland) at the research station Osservatorio Ticinese Locarno-Monti della Centrale Meteorologica Svizzera     

An approach to problems on energy sources at Mount Etna based on seismological and volcanological data

Based on seismograms from the most continuously operating station of the seismic network at Mt. Etna (Monte Vetore, 1665 m a.s.l.), the energy release patterns through time have been obtained for volcanic tremors and earthquakes which occurred between 1978–1982. Both energies range between 10¹¹10¹³ J/a, but their release patterns are not strictly correlated to each other. Considering only the eruptions which occurred during the same time span, the amount of thermal energy released and the associated potential energy needed to raise the magma to the surface from a 2-km-deep hydrostatic equilibrium level were estimated to be about 10¹⁷ and 10¹⁵ J/a, respectively. The computed energies for earthquakes and tremors are at least one order of magnitude less than what is needed to match a model of magma transport based solely on the jerky propagation of melt-filled cracks. The energy needed to raise the magma to the surface could be supplied by expanding gases in the upper levels of the magma column and/or by tectonic stresses acting on shallow batches of magma.Paper presented to the HVO Int. 1 Symposium on How volcanoes work, Hilo, Hawaii, 18–23 January 1987;     

On the efficiency with which aerosol particles of radius larger than 0.1 μm are collected by simple ice crystal plates

A theoretical model is presented which allows computing the efficiency with which aerosol particles of radius 0.1r10 m are collected by simple ice crystal plates of radius 50a _c 640 m in air of various relative humidities, temperatures and pressures. Particle capture due to thermophoresis, diffusiophoresis and inertial impaction are considered. It is shown that the capture efficiency of an ice crystal in considerably affected by phoretic effects in the range 0.1r1 m. For aerosol particles ofr>1 m the efficiency is strongly controlled by the flow field around the crystal and the density of the aerosol material. Trajectory analysis also predicts that aerosol particles are preferentially captured by the ice crystal rim. Our theoretica results are found to agree satisfactorily with the laboratory studies presently available. Comparison shows that for the same pressure, temperature and relative humidity of the ambient air ice crystal plates are better aerosol particle scavengers than water drops.     

Höhe der Windsee in einem wandernden rechteckigen Windfeld

Zusammenfassung Die hauptsächlich in der amerikanischen Literatur gegebenen Anweisungen zur Berechnung der Windsee aus dem herrschenden Wind gelten im allgemeinen für nicht-wandernde Windfelder. Hier wird gezeigt, daß bei den für die praktische Seegangsvorhersage häufig bedeutungsvollen wandernden Windfeldern der entstehende Seegang auch abhängig ist von der Breite des Windfeldes, von seiner Verlagerungsgeschwindigkeit und von dem Winkel, den Windrichtung und Zugrichtung des Windfeldes bilden. Die wichtigsten der verschiedenen Situationen, die sich ergeben können, werden behandelt. Dabei werden Hinweise für die Berechnung eines effektiven Fetch und einer effektiven Windwirkungsdauer gegeben, mit denen die von einem wandernden Windfeld erzeugte Windsee annähernd bestimmt werden kann.

---

On the height of the wind sea in a travelling rectangular fetch

Summary Recent papers, chiefly such of American origin, often discuss methods enabling wind generated sea to be derived from the dominating wind. These methods refer, in general, to non-travelling fetches. The present paper deals, however, with the problem of travelling fetches which are often of greater importance to practical sea forecasting. It is shown that in the case of wandering fetches the wind generated sea is also a function of the fetch's width, of its displacement speed and of the angle between the wind's direction and the direction of displacement of the fetch. The most important of the various situations that occur are discussed and instructions are given to compute the effective fetch and the effective duration of the wind's action as these data will allow to approximately determine height and period of a wind sea from a travelling fetch.

---

Sur la hauteur des vagues soulevées par le vent d'un »fetch« rectangulaire en mouvement

Résumé Des publications récentes, surtout telles venant des Etats-Unis, exposent des méthodes permettant de dériver du vent actuel les vagues de vent; ces méthodes se réfèrent, en general, à des »fetches« stationnaires. Le présent travail, cependant, traite le problème des »fetches« en mouvement qui sont souvent d'une importance plus grande à la prévision pratique de la mer du vent. On montre que les vagues du vent, en train de naître, sont aussi fonction de la largeur du »fetch«, de sa vitesse de déplacement et de l'angle formé par la direction du vent et la direction du mouvement du »fetch«. Alors, on discute des nombreuses situations les plus importantes qui peuvent se réaliser, donnant, en même temps, des instructions à évaluer »le fetch effectif« et »la durée effective de l'action du vent«; ces données permettent de dériver approximativement la force et la période des vagues engendrées par le vent d'un »fetch« progressif.

     

Measurement of small ions and condensation nuclei over the sea near the land

Summary To study the ionization equilibrium, simultancous measurements of the concentration of small ions (n), concentration of condensation nuclei (Z), and the diffusion coefficient of condensation nuclei (D) have been carried out over the sea. If we take the variation ofD into consideration, the correlation among them was found to be well expressed by the simple formula;q=n Z. The dependence of the effective attachment coefficient of small ions () upon the size of nuclei (2r) were also studied, and was found to correlate well withD orr. Slight differences of the dependence of uponD orr over the sea from that over the land seem to be well explained by the difference of charged states of nuclei over the sea and land.

---

Zusammenfassung Zur Untersuchung des Ionisationsgleichgewichts wurden gleichzeitige Messungen der Konzentration schneller Ionen (n), der Konzentration der Kondensationskerne (Z) und des Diffusions-Koeffizienten der Kondensationskerne (D) über dem Meere ausgefürt. Unter Berücksichtigung des Diffusions-Koeffizienten (D) konnte der Zusammenhang zwischen den beiden anderen Grössen recht gut durch eine einfache Formel ausgedrückt werden:q=n Z. Die Abhängigkeit des wirksamen Anlagerungskoeffizienten für schnelle Ionen () von der Grösse der Kondensationskerne (2r) wurde ebenfalls untersucht, und es wurde gefunden, dass recht gut mitD oderr korreliert. Kleinere Unterschiede in der Abhängigkeit von vonD oderr, welche bei einem Vergleich der Messungen über See und über Land festgestellt wurden, liessen sich gut durch den Unterschied der geladenen Zustände der Kondensationskerne über See und Land erklären.

     

Chemistry of atmospheric aerosols

Summary A survey is given on the present status of knowledge about the chemical composition of atmospheric aerosols. Results on the size distribution and the physical structure of the nuclei provide the necessary basis for an under-standing of their chemistry. Very little is known about the chemistry of particles smaller than 0.1. For larger particles micro-analyses show the presence of sulfate, nitrate, chloride, sodium and ammonium which varies in a characteristic way with the size of the particles. The sea spray component can be isolated. Data from rain water analyses are used to obtain information on the large scale distribution of these components and their sources. Some remarks about the fraction of the particles acting as true condensation nuclei and the radioactivity will conclude the paper.The subject has been already developed in detail inAdvances of Geophysics, Vol. 4 (edited byH. E. Landsberg & J. van Miechem), Academic Press Inc., New York, 1958.     

Models for the origin of accretionary lapilli

Binding between initially cohesionless ash particles to form concentric accretionary lapilli is provided primarily by the capillary forces of liquid bridges from condensed moisture and by electrostatic attraction. Capillary forces are strong bonds if the particles are in close contact, but they decrease rapidly with increasing particle spacing. Electrostatic attraction between charged ash particles is much weaker but effective over larger distances, increasing the frequency of collision between them.Experimental results of liquid film binding of volcanic ash showed that agglomeration was most successful between 15 and 25 wt.%, defining the agglomeration window for the formation of accretionary lapilli. Below 5–10 wt.% and above about 25–30 wt.% of water, concentric agglomeration was inhibited. Particles <350 m could be selected from a wider particle population in the experiments using only small amounts of water, which can explain the growth of accretionary lapilli in pyroclastic surges around agglomeration nuclei. Experiments testing the behavior of volcanic ash in electric fields showed that ash clusters formed instantaneously when the ash entered the field between a corona discharge gun and a grounded metal plate. The maximum grain size incorporated into the artificial clusters was about 180 m but >90 wt.% of ash was <45 m.Accretionary lapilli form in turbulent ash clouds when particles carrying liquid films of condensed moisture collide with each other and when the binding forces exceed the grain dispersive forces. Larger particles >500 m act as agglomeration nuclei in surges, accreting ash <350 m around them. In pyroclastic flows the aggregates are thought to originate from already size-sorted ash at the interface between the lower avalanche part of the flow and its overriding elutriation cloud. The fine-grained rims around accretionary lapilli found close to source are interpreted to be accreted dominantly by electrostatic attraction of very fine ash similar to clustering in elutriation clouds.     

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).     

Eine neue Methode der Kondensationskernzählung

Zusammenfassung In der vorliegenden Arbeit wird eine Methode beschrieben, die es gestattet, mit Hilfe lackierter Glasplatten Kondensationskerntröpfchen oder andere Tröpfchen mit einem Durchmesser von 5 zu fixieren und dann elektronisch auszuzählen. Vorversuche, bei denen diese Methode angewendet wurde, machen es wahrscheinlich, dass bei Kondensationskernzählern, die nach dem Expansionsprinzip arbeiten, ein Teil der Kerne wegen ihrer Aktivität schon vor der Expansion als Wassertröpfchen ausfällt und damit der Zählung entgeht.

---

Summary In the present paper a method is described, which allows to fix droplets of condensation nucleus or other droplets (diameter 5 ) by means of varnished plates of glass and count them afterwards electronically. Preliminary experiments with this method show up the probability, that in the nucleus counter, working on the principle of expansion, some of the very active nucleus drops out before the expansion chamber is dilated and thus escapes registration.

---

Riassunto Nella presente ricerca si descrive un metodo il quale consente di fissare goccioline provenienti da nuclei di condensazione, o altre goccioline (diam. 5 ), su dischi di vetro verniciati, e in seguito di contarle elettronicamente. Prove eseguite con questo metodo rendono probabile che, in contatori di nuclei di condensazione che lavorano secondo il principio dell'espansione, una parte dei nuclei, in seguito alla loro stessa attività, cada sotto forma di goccioline d'acqua già prima dell'espansione e che quindi sfugga al conteggio.

     

Rock Magnetic Investigation of Historical Lavas Used in Palaeointensity Studies

Five samples from historical lava flows on Mt. Etna, which had previously been used in a palaeointensity study, were examined using a combination of rock magnetic and microscopic techniques to elucidate the causes of failure of palaeointensity determination. The samples were characterised using a combination of low-temperature susceptibility (LT-), Bitter pattern imaging and scanning electron microscope (SEM). High-temperature susceptibility curves and hysteresis loops had been previously measured by Calvo et al. (2001). Of the five samples only one gave an accurate palaeointensity. This sample was deuterically oxidised and consisted of large exsolved ore grains. It was only possible to distinguish this sample either optically or magnetically from a similar sample by the LT- warming curves; the unsuccessful sample displayed alteration in the LT- warming curves, which was not readily observed in the high temperature susceptibility curves. It is proposed that the measurement of LT- curves before and after heating could be a more sensitive method of determining suitability for palaeointensity determination than previous rock magnetic pre-selection techniques.     

Precipitation types in winter storms

The characteristics of and the evolution between snow, rain, ice pellets, and freezing rain are discussed. Precipitation type and the nature of its size distribution and extent are related to the melting behaviour of snow. Model calculations of this melting show the progression of precipitation type from freezing rain to ice pellets and finally to snow, as melting systematically erodes an upper level inversion within about 5 h for a precipitation rate of 1mm h^–1. The increase in temperature of the low level subfreezing region associated with ice pellet formation (up to 1°C) should furthermore be detectable. These phase transitions between the various precipitation types, as affected by atmospheric cooling by melting, are predicted to occur over mesoscale distances.     

Organochlorine pesticides in fresh-fallen snow on East Rongbuk Glacier of Mt.Qomolangma (Everest)

During a field campaign in April 2005,fresh-fallen snow samples were collected on the East Rongbuk Glacier of the Mt. Qomolangma at four altitudes (6500 m,6300 m,6100 m and 5900 m),to study the role of Mt. Qomolangma as "cold-traps" for Persistent Organic Pollutants. From these snow samples col-lected at the highest-altitude,organochlorine pesticides (OCPs):HCB,p,p′-DDT and p,p′-DDD were detected,with the concentrations in the ranges of 44―72 pg/L,401―1560 pg/L,and 20―80 pg/L,re-spectively. The concentration of o,p′-DDT was around the method detection limit. Analysis of backward trajectories showed that the detected compounds came from the north of India,suggesting that DDTs detected in the snow were possibly originated from new emissions in this area. Relationships between the concentrations of OCPs in snow samples and the sampling altitudes were discussed. The altitudes had no obvious effect on HCB concentrations in the fresh-fallen snow,while increases in the concen-trations of p,p′-DDT and p,p′-DDD with increasing altitude were found,which was reversed compared to the trends observed in North America. Three factors likely resulted in this trend: (1) the properties of the target compounds; (2) the low temperatures at high altitudes; and (3) the location of the mountain sampling sites relative to their sources.     

Characteristics and distribution patterns of snow and meteoric ice in the Weddell Sea and their contribution to the mass balance of sea ice

Based on snow- and ice-thickness measurements at >11 000 points augmented by snow- and icecore studies during 4 expeditions from 1986 - 92 in the Weddell Sea, we describe characteristics and distribution patterns of snow and meteoric ice and assess their importance for the mass balance of sea ice. For first-year ice (FY) in the central and eastern Weddell Sea, mean snow depth amounts to 0.16 m (mean ice thickness 0.75 m) compared to 0.53 m (mean ice thickness 1.70 m) for second-year ice (SY) in the northwestern Weddell Sea. Ridged ice retains a thicker snow cover than level ice, with ice thickness and snow depth negatively correlated for the latter, most likely due to aeolian redistribution. During the different expeditions, 8, 15, 17 and 40% of all drill holes exhibited negative freeboard. As a result of flooding and brine seepage into the snow pack, snow salinities averaged 4‰. Through ¹⁸O measurements the distribution of meteoric ice (i.e. precipitation) in the sea-ice cover was assessed. Roughly 4% of the total ice thickness consist of meteoric ice (FY 3%, SY 5%). With a mean density of 290 kg/m³, the snow cover itself contributes 8% to total ice mass (7% FY, 11% SY). Analysis of ¹⁸O in snow indicates a local maximum in accumulation in the 65 to 75^S latitude zone. Hydrogen peroxide in the snow has proven useful as a temporal tracer and for identification of second-year floes. Drawing on accumulation data from stations at the Weddell Sea coast, it becomes clear that the onset of ice growth is important for the evolution of ice thickness and the interaction between ice and snow. Loss of snow to leads due to wind drift may be considerable, yet is reduced owing to metamorphic processes in the snow column. This is confirmed by a comparison of accumulation data from coastal stations and from snow depths over sea ice. Temporal and spatial accumulation patterns of snow are shown to be important in controlling the sea-ice cover evolution.     

Analysis of Changes in the Aral Sea Coastal Zone in 1975–1999

Changes in the Aral Sea coastline and coastal zone over different time intervals during the period of the sea level drop are studied with the use of space photographs obtained from the orbital station Salyut-4 and satellites of the Resurs-O system. Interannual variations in the above characteristics are analyzed for 1975–1989, 1989–1993, 1993–1996, 1997, 1998, and 1999. Seasonal variations in the water area and coastal landscapes are studied with the help of photographic images of the sea made in different seasons, mainly in 1998.     

A stochastic differential equation approach to soil moisture

The dynamics of water within the unsaturated root zone of the soil are represented by a pair of stochastic differential equations (SDE's), one representing the so-called surplus state of the moisture and the other the deficit condition. The inputs to the model are the climatically controlled random infiltration events and evapotranspiration which are modeled as a compound Poisson process and a Wiener (Brownian motion) process, respectively.The solutions to these SDE's are not in close-form but sample functions are obtained by numerical integration. The moment properties of the soil moisture evolution process have also been derived analytically including the mean, variance, covariance and autocorrelation functions.To illustrate the model, climatic parameters representing the surplus and deficit cases and properties of clay loam soil have been used to numerically derived the corresponding sample functions. With proper selection of all the parameters, physically realistic sample trajectories can be obtained for the model.     

Digital topography of volcanoes from radar interferometry: an example from Mt Vesuvius,Italy

A new airborne radar technique can generate digital topographic data for volcanoes at a scale of 10 m spatial and 1–5 m vertical, with a swath width of 6.4 km. Called TOPSAR, the intrument is an interferometric radar flown on the NASA DC-8 aircraft. TOPSAR data permit the quantification of volcano slopes, volumes, and heights, and as such will be valuable for the analysis of lava flows, domes, and lahar channels. This instrument will be flown over several volcanoes in the near future, providing volcanologists with valuable data sets for the analysis of high-resolution topography. We briefly illustrate the potential use of TOPSAR data through examples from Mt Somma and Vesuvius, Italy.     

Divergent distributions of prey and predator,a fishing effect?

To compare the vertical distributions of benthos and fish species of Upper Lake Constance (Bodensee), 552 benthos samples were taken with an Auerbach grab at four transects (10–250 m). An additional 54 samples (1–10 m) were collected elsewhere. Complementary data was taken from the literature. In winter, most fish feed on benthos, mainly chironomids, but in summer less than 5% do so. Formerly the bottom gill-netting aimed mainly at catchingCoregonus pidschian, but it now aims atPerca fluviatilis. Contrary to expectation, in winter the greatest abundance ofP. fluviatilis is much deeper (55 m) than that of its preferred food, i.e. chironomids (<20 m). Comparably,C. pidschian also stayed deeper than its main food source (chironomids and mollusks).Lota lota, Salvelinus profundus andS. alpinus — unlike the unwanted cyprinids — also stay or stayed deeper than the attractive chironomids. It is argued that the fish reduce their predation risk, i.e. the risk of being gillnetted in the upper 50 m, by selecting the deeper less dangerous, but also less food-abundant habitat. Balancing predation risk against food abundance may have led to survival of the deepest.