The thermal diffusivity of red sandy soil at Waltair

Summary The study of heat exchanges or temperature changes in the surface layers of the soil are important in agricultural science at tropical latitudes. The quantity, thermal diffusivity largely determines the temperature change produced in any layer of the soil when heat is conducted there from an adjacent layer. Therefore, the authors have determined the thermal diffusivity of the soil from range and lag methods suggested byJohnson andDavies [15]²) andCoutis [7] respectively. The values of diffusivity cbtained from these methods agree well with each other. The effect of soil moisture on diffusivity has been studied. The diffusivity increases with the increase of moisture in the surface layers of the scil. The ratio of ranges of soil temperature at different depths is found to be approximately constant which is in agreement with the theory of heat flow into the soils. The results of diffusivity obtained from these methods agree well with those results of past workers. The mean value of the thermal diffusivity of red sandy soil at the experimental site of Waltair is found to be 6.336×10^–3 cm²/sec.     

Terrestrial heat flow from project CESAR, Alpha Ridge, Arctic Ocean

During two months in spring, 1983, a multidisciplinary study, project CESAR, was undertaken from the sea ice across the eastern Alpha Ridge, Arctic Ocean. In the geothermal program, 10 gradiometer profiles were obtained; 63 determinations of in situ sediment thermal conductivity were obtained with the same probe, and 714 measurements of conductivity using the needle probe method were obtained on nearby core.Weighted means of the thermal conductivity of the sediment are 1.26 W/mK (in situ) and 1.34 W/mK (core), consistent with the compacted sediment encountered across the ridge and with the lithology. Calculated terrestrial heat flow values, corrected for the regional topography, range from 37 to 72 mWm⁻²; the average is 56+/−8 mWm⁻².Some temperature and heat flow versus depth profiles exhibit non-linearities that can be explained by physically reasonable (but otherwise unsubstantiated) variations in bottom water temperatures preceding the measurements; models are hypothesized that reduce the curvatures. Two heat flow values considerably higher than others in the area may be explained by higher bottom water temperature over several years, while the low value is consistent with a recent deposition from a slump. This hypothetical modelling reduces the scatter of heat flows and reduces the average to 53+/−6 mWm⁻².The CESAR heat flow is somewhat greater than expected for a purely continental fragment but is consistent with crust of oceanic origin. The heat flow is similar to values obtained in Cretaceous back-arc basins. Based on the oceanic heat flow-age relationship, the heat flow constrains the age of the ridge to 60–120 million years. The heat flow observed on other aseismic features in the world's oceans suggests that the Alpha Ridge has experienced no significant tectono-thermal event in the last 100 million years.     

On waves generated by a moving pressure field,II: Cnoidal wave effects

Summary In a recent paperHunt andTanner [3]²) investigated the waves generated by a steadily moving two-dimensional pressure distribution, which was zero ahead of the disturbance and a constantp ₀, tehind it, these regions being joined smoothly by a cubic function. Only those solutions with supercritical flow in both regions were considered, these were found to lead to an asymmetric solitary wave.This result is now extended to take account of the possibility of subcritical flow in either or both the regions, that is when there is a cnoidal wave train either behind and or ahead of the main solitary wave crest.The wave profiles are determined by the iterative method employed in the previous paper. This together with the wave drag associated with each system is computed for various values ofp ₀/U ², where is the fluid density andU a typical velocity.     

Thermal structure and energy of the Hakone volcano,Japan

The thermal energy balance and the temperature profile of the Hakone volcano are considered quantitatively. Across the Hakone volcano and its surroundings the heat flow values vary from 10^–1 to 10³ mW/m², due to thermal conduction and mass flow involving volcanic steam and hot spring discharge. An area with extremely low heat flow is observed in the western side of the caldera showing the presence of percolating meteoric water. The hydrothermal activity is intense in the eastern half of the caldera.The total heat discharge from the high temperature zone (discharge area) of the Hakone volcano amounts to 11.0×10⁷ W. The magmatic steam energy discharge is 95.0×10⁶ W. The thermal energy by redistribution of the terrestrial heat flow by the lateral deep ground water flow is calculated to be 9.00×10⁶ W. For the model having the vertical vent in the volcano's central part up to 1 km depth below the ground surface from a magma reservoir the computed temperature distribution is consistent with the observed values. The depth of the magma reservoir is 7 km below the ground surface and the diameter is 5 km.     

A simple formula for the second derivative method of interpretation

Summary Second derivative coefficients for various grid systems are derived followingPeters' andElkins' approaches. Two simple formulae, one for three dimensional bodies and the other for two dimensional bodies are also suggested. These utilise the average of the anomalies around a single circle and the anomaly at the central point.All the coefficient sets and the proposed simple formulae are applied to gravity fields of spheres and cylinders. Coefficients ofElkins' type derived with a weightage of 1/r ⁴ to all the circles gave excellent results in both the cases of spheres and cylinders, whereasPeters' coefficients without any weightage to the circles gave reliable results in case of cylinders only. The simple formulae suggested gave more accurate results than any of the above coefficient sets.     

Some hydrodynamic problems for a nepheloid zone

Summary A layer of a few hundred meters thickness with suspended matter (a nepheloid zone) was discovered byEwing andThorndike [4]³⁾ near the bottom on the continental slope of the North Atlantic. A downward pressure gradient is produced in this layer due to increment of water density with suspensoid. When only the Coriolis force balances with this pressure gradient, a bottom nepheloid current flows southwestward parallel to the depth contours with a velocity of about 10 (cm/sec) for a slope of one degree. The pressure gradient for fluid with locally variable density above a sloping bottom is treated and an extra term due to density gradient along the slope is derived. The vertical profiles of the nepheloid current with an effect on the vertical eddy viscosity are computed. Two kinds of vertical distributions of eddy viscosity are determined from the observed nepheloid distributions and used in the calculations: constant but different values at two layers and those increasing with height. The effect of the change of density along the bottom is treated by introducing dimensionless variables. Rossby number of the nepheloid current becomes about 10^–2 indicating inertia terms to be negligible. Rossby number of turbidity currents ranges from 2 (in a decaying area) to 5 (developing area), suggesting that inertia terms are more important than Coriolis terms. The trajectories of turbidity currents are computed from motion of a mass of mud under the Coriolis force and friction, and the results are applied to those inferred byHand andEmery [6] in the San Diego Through off California.LGO Contribution Number 925.     

On the geothermal regime of some tectonic units in Romania

Heat flow values of 33–58 mW m^–2 were found for the Transylvanian Depression, 45–57 mW m^–2 for the crystalline nucleus of the Eastern Carpathians, and 70–120 mW m^–2 for the Neogene volcanic area. Temperature-depth profile and some geophysical implications of the low values for the Transylvanian Depression are discussed, rendering evident clear-cut differences between this tectonic unit and other Noegene depressions. The heat flow values for the other two investigated tectonic units are usual ones for areas of their age.A preliminary map of the heat flow distribution over the Romanian territory is presented and its relation to other geophysical fields is discussed. A positive correlation was found between gravity and heat flow, and a negative one between crustal thickness and heat flow. A general conclusion could be drawn that the heat flow distribution over the Romanian territory seems to be governed by processes taking place in the upper mantle, rather than by the radioactive decay within the crust.     

Multiasperity fault model and the nature of short-period subsources

We suggest to consider the breaking of an asperity,i.e., a small contact patch between fault walls, as a typical subsource producing an elementary short-period radiation pulse from a source of a large earthquake. Based on the results ofDas andKostrov we propose formulas to describe amplitudes and spectra of acceleration for a multiasperity fault/source model. The stress drop over an asperity is determined in several ways; the estimates agree to give the average value of several hundred bar. Theoretical acceleration spectral shapes for the case of similar asperities agree with the observed ones, they reproduce such features as lower-frequencyf ¹ slope, peak, and high-frequency cutoff. The statistical stress-drop distribution over the population of asperities, and also the related distribution of peak accelerations are discussed. There distributions are found to be the power-law ones with exponent near to 2. This means that acceleration peaks are formed normally by breaking of individual asperities. We consider small earthquakes as produced by breaking of single asperities, this idea explains the observed correlation between the upper cutoff frequency of acceleration spectrum and the typical characteristic frequency of small earthquakes.     

Der doppelperiodische Tagesgang des luftelektrischen Potentialgefälles als Folge des Austausches

Zusammenfassung Die vonJ. G. Brown vertretene Auffassung, den doppelperiodischen Tagesgang des luftelektrischen Potentialgefälles an Landstationen als Ueberlagerung eines einfach- periodischen Ganges und einer austauschbedingten Depression darzustellen, wird mit Hilfe berechneter Tagesgänge des Austauschkoeffizienten quantitativ bestätigt.

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Summary Following a suggestion ofJ. G. Brown of regarding the local variation of the earth's electric field at land-stations as mainly caused by the cycle of turbulence, convection, and subsidence the problem of the double-period of the daily variation of the earth's electric field has been numerically solved. By computed values of the daily variation of the «Austauschkoeffizient», an exact measure of atmospheric turbulence, basing on temperature observations of Leafield (England) for clear days, the daily variation of nuclei has been computed for; thus getting additionally the daily variation of ions, conductivity, and local potential-gradient. Combining this computed variation of the potential-gradient and the unitary variation of the earth's field over oceans shows a double-period (local time) of the potential-gradient of the earth's electric field at land-stations. Thus the problem of the double-period of the daily variation of the earth's electric field has been reduced to one of a single-period which cannot be explained by the «Austausch».

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Herrn Prof. Dr.W. Peppler zum 65. Geburtstag gewidmet.     

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.     

Statistical analysis of the effects on overland flow of spatial variability in soil hydraulic conductivity / Analyse statistique des effets de la variabilité spatiale de la conductivité hydraulique du sol sur l'écoulement de surface

Abstract

The effects of spatial variation of the saturated hydraulic conductivity (K _s ) of the soil on the variation of overland flow were tested by analysing 2000 synthetic rainfall—runoff events, all generated from real, observed rainfall events but with runoff modelled by a two-dimensional distributed model using different spatially variable K _s fields in a small (12 ha) agricultural catchment. The purpose is to determine the influence of spatial variation in K _s on runoff generation. The statistical measures used to describe the variation in the generated K _s were its coefficient of variation and correlation length. Both of these had two levels of typical values obtained from field measurements in other studies. The storms were analysed at a general event level, first using simple graphical and statistical methods and then using analysis of variance (ANOVA). The observed scale of the spatial variation of K _s does cause statistically significant variation in overland flow. The graphical analysis showed that the first flow peak in a multi-event storm had the largest variation and that differences were greater in the rising part of the hydrograph than in its recession. The greatest variation in overland flow was produced by the combination of the greater coefficient of variation and the longer correlation lengths. The smallest variation in overland flow was produced by the combination of the smaller coefficient of variation and the shorter correlation lengths. ANOVA showed that the coefficient of variation and correlation length alone did not explain all the variation of the total flow. ANOVA was not very useful due to the many restrictive assumptions that were not satisfied by the nature of the data and therefore analysis methods with less restrictive assumptions need to be tested.     

Nonuniform friction as a physical basis for earthquake mechanics

A review of simple models and observations suggests that the main first-order features of active faulting-mechanical instability, the frequency-magnitude relations, seismic and aseismie slip, seismic radiation, incoherency and rupture stoppage — may be explained by a single characteristic of crustal faults: the spatial variation of the effective frictional stress, which resists slippage on faults. Faultoffset data suggest that rupture propagation ceases in regions of high resistance which act, as barriers. In these regions slippage is associated with negative stress drop. The spacing and the amplitudeA() of the barriers, as inferred from the frequency-magnitude and moment relation for earthquakes, obeys a simple statistical relationA()^p. On the scale of particle motion, this variability of frictional stress provides a mechanical instability which may be associated with the concept of dynamic friction. Invariably, the rapid particle motion in the model is always preceded by accelerated creep. The particle acceleration is highly irregular, giving rise to an almost random acceleration record on the fault. The particle displacement is relatively smooth, giving rise to simple displacement time function in the far field. Rupture propagation time is approximately proportional to the gradient of frictional stress along the fault. Consequently sharp changes of this stress may cause multiple events and other long period irregularities in the fault motion.The power density spectrum associated with the frictional stress implies that stress may be related to a Poisson distribution of lengths. The autocorrelation of such type of distribution yields a correlation lengthk _L ^–1 , similar perhaps toHaskell's (1964) andAki's (1967) correlation lengths inferred from spectral analysis of seismic waves. The partial incoherency of faulting implies that preseismic deformation may be significantly incoherent, consequently the prediction of small moderate earthquakes may be subject to inherent uncertainties. We conclude that frictional stress heterogeneities may be necessary and sufficient to explain active faulting associated with small and moderate earthquakes.     

Global heat flow: A new look

A global heat flow map has been derived from existing observations supplemented in areas without data by an empirical predictor based on tectonic setting and age. In continental areas the predictor is based on the observed correlation of heat flow with age of last tectono-thermal event, and in oceanic regions on the observed relation of heat flow to age of ocean floor. The predictor was used to assign mean heat flow values to 5° × 5° grid areas on the globe, weighted according to the relative area of tectonic provinces represented. A spherical harmonic analysis to degree 12 of the heat flow field yields a mean value of 59 mW m^?2, a rms residual of 13 mW m^?2, and an amplitude spectrum which decreases gradually and almost monotonically fromn = 1. The spherical harmonic representation of the heat flow field is free of the unreal distortions which have characterized earlier analyses based on a geographically sparse data set. Areas with residuals greater than 15 mW m^?2 comprise less than 19% of the area of the globe, thus indicating that most heat flow provinces have characteristic dimensions adequately represented in a 12-degree analysis.     

Coupled groundwater flow and heat transport simulation for estimating transient aquifer–stream exchange at the lowland River Spree (Germany)

Subsurface flow and heat transport near Freienbrink, NE Germany, was simulated in order to study groundwater–surface water exchange between a floodplains aquifer and a section of the lowland River Spree and an adjacent oxbow. Groundwater exfiltration was the dominant process, and only fast surface water level rises resulted in temporary infiltration into the aquifer. The main groundwater flow paths are identified based on a 3D groundwater flow model. To estimate mass fluxes across the aquifer–surface water interfaces, a 2D flow and heat transport modelling approach along a transect of 12 piezometers was performed. Results of steady‐state and transient water level simulations show an overall high accuracy with a Spearman coefficient ρ = 0.9996 and root mean square error (RMSE) = 0.008 m. Based on small groundwater flow velocities of about 10^?7 to 10^?6 ms^?1, mean groundwater exfiltration rates of 233 l m^?2 d^?1 are calculated. Short periods of surface water infiltration into the aquifer do not exceed 10 days, and the infiltration rates are in the same range. The heat transport was modelled with slightly less accuracy (ρ = 0.8359 and RMSE = 0.34 °C). In contrast to the predominant groundwater exfiltration, surface water temperatures determine the calculated temperatures in the upper aquifer below both surface water bodies down to 10 m during the whole simulation period. These findings emphasize prevailing of heat conduction over advection in the upper aquifer zones, which seems to be typical for lowland streams with sandy aquifer materials and low hydraulic gradients. Moreover, this study shows the potential of coupled numerical flow and heat transport modelling to understand groundwater–surface water exchange processes in detail. Copyright © 2013 John Wiley & Sons, Ltd.     

On the possible influence of meteoritic dust on rainfall

Summary This article comments on the statistical aspects of the calculations inBowen’s article on the influence of meteoritic dust on rainfall.Bowen seems to have neglected the phenomenon of self correlation in the series of rainfalls on successive days. This neglect made his conclusions rather significant, but when the self correlation is considered in the right way many of his results become insignificant and the question whether the meteoritic dust has the influence mentioned above remains unanswered. We applied the range and the so called constellation test. Especially stress is laid on the necessity of developing a coincidence test, which furnishes the probability of coinciding of peaks (one peak in one series, one peak in another one) even if the peaks are statistically unreal and of course the persistence ought to be considered. Three types of such a test were proposed. We also introduced a new way of tackling the problem stated byBowen. — SinceHannan published the numerical values of the serial correlation coefficients for Sydney (the rainstation used byBowen) we were able to give a more numerical basis to our critical remarks. Dr.C. Levert, Royal Netherlands Meteorological Institute,De Bilt (Holland).     

Depression in the low-latitude horizontal intensity due to quiet-time ring current

Summary The external field due to plasma within the magnetosphere has been computed as a function ofA _p, which is a measure of solar wind velocity, for very quiet to slightly disturbed conditions using mean daily horizontal intensity from 1932 to 1968 at Alibag. The intensity, corrected for secular change and reduced to a common epoch, showed initially a small increase withA _p followed by a steady depression with further increase in the index. ForA _p7.5, which is representative of conditions over the 33-hour interval during which data relating to low-energy protons were acquired and used byHoffman andBracken [4]²) to compute current distributions, the decrease, computed here from surface data, is 6 . This is in goodagreement with the southward directed field of the quiet-time proton belt 9±5 obtained byHoffman andBracken.     

Heat flow and depth versus age for the Mesozoic northwest Atlantic Ocean: results from the Sohm abyssal plain and implications for the Bermuda Rise

Heat flow in the Sohm abyssal plain is measured to be 53 mW/m² at an age of 163 Ma. This is 25% higher than predicted by conductive cooling models, even though the sediment-corrected basement depth of 6.5 km at this location is normal for its age. An analysis of existing heat flow, depth and geoid anomalies in the northwest Atlantic shows that there is little correlation between heat flow and depth throughout the entire region. Depth and geoid are clearly related to the Bermuda swell while the associated heat flow anomaly, once adjusted for variations with age, is limited to 5 mW/m² and only decays to the south. This means that the Bermuda swell is probably not caused by extensive thermal reheating within the lithosphere, but instead by dynamic uplift at its lower boundary due to the convective upwelling of a mantle plume. The regionally high heat flow in the northwest Atlantic may be a thermal remanent of previous plumes which passed beneath this region early in its history. Therefore, depth and heat flow anomalies from this region cannot be used to provide constraints on steady-state parameters of the lithosphere, such as the presence or absence of a long-term boundary layer at its base.     

Light scattering constants for a water cloud

Summary The study of radiative transfer in clouds and fog requires a knowledge of basic radiation constants. For this purpose the volume extinction, scattering, and absorption coefficients, the maximum absorption coefficients for composite spectral lines, and the coefficients used to expand the phase function into a series of Legendre polynomials for analytic representation of the phase function are provided in tabular and graphical format. The analysis for cloud droplets is based upon the rigorous electromagnetic theory. All Mie computations are carried out in an exact manner avoiding any approximations. Absorption line constants as computed here are based upon the investigations ofElsasser withCulbertson [5]³) andWyatt, Stull, andPlass [18]. Tabulations are made on the basis of fifty spectral intervals covering the entire solar and infrared spectra. Polarization effects are disregarded in this study.     

Curie-point Depth from Spectral Analysis of Magnetic Data in Erciyes Stratovolcano (Central TURKEY)

Curie-point depth and heat flow values of the Erciyes region are determined to identify the thermal regime of the Central Anatolia by applying the spectral analysis method to the magnetic anomaly data. To compute the spectrum of the data, the magnetic anomaly of the region is transformed into 2-D Fourier domain to attain the average Curie depth. This method is useful in determining the top boundary of magnetic anomaly sources and reveals the Curie depth as 13.7 km in the study area. The obtained results imply a high thermal gradient (42.3°C km^?1) and corresponding heat flow values (88.8 mWm^?2) in the research area. Using the temperature value measured at borehole drilled by the General Directorate of Mineral Research and Exploration of Turkey (MTA), the values for the thermal gradient and heat flow value were computed as 50.7°C km^?1, 106.5 mWm^?2. From the heat flow value, the Curie-point depth was determined as 11.4 km in this region. It is concluded from the obtained values that the region has very high geothermal potential caused by partial melting of the lower crust.     

The removal rates of234Th and228Th from waters of the New York Bight

The mean residence time (τ) of thorium with respect to non-radioactive removal from water was determined as a function of location in three traverses of the New York Bight using both²³⁴Th/²³⁸U and²²⁸Th/²²⁸Ra. τ correlates well with salinity increasing from about ten days near shore to 70 days at the shelf break. It shows a much weaker correlation with suspended matter concentrations both because suspended matter varies in its scavenging efficiency and because salinity is a longer-term integrator of scavenging potential.τ's computed from²²⁸Th/²²⁸Ra were often higher than those computed from²³⁴Th/²³⁸U either because of the detrital matter present as reflected in the²³²Th concentrations or because the water parcels had recently arrived from environments of lower scavenging efficiency.Anomalous isotopic concentrations found in three adjacent samples can best be explained as the result of an episodic release of²²⁸Ra from bottom sediments at a rate 200 times the normal one.