On the heat budget of the moon and the surface temperature variation during a lunar eclipse     

Dr. Heinz Lettau 《Pure and Applied Geophysics》1951,19(1-2):1-18

Summary The analysis of surface temperature variations of the moon is based on the equations of heat conduction and heat continuity in the interior of the moon andStefan's law. During a well-defined process, as exemplified by a lunar eclipse, the local heat budget equation establishes a boundary condition at the moon surface which must be satisfied by solutions of the thermal diffusion equation in the interior. Three simplified models of the general case are discussed. They are characterized by special assumptions regarding the depth and time dependency of the thermic qualities of the material underlying the moon's surface. In short, the thermal diffusivity is assumed to be constant in the first model, a linear depth function in the second and a time function in the third. A unique solution can be obtained for model No. I such that the absolute surface temperature is approximately inversely proportional to the 6th root of time during the phase of total eclipse.Epstein's conclusion that the average surface of the moon might consist of highly porous rocks or fine dust is confirmed by the order of magnitude of the heat conductivity which produces the best fit between the theoretical curves and a plot ofPettit's observational data during the lunar eclipse of 1939. Existing differences between the observed and theoretical curves during the totality phase of the eclipse can be reduced by the employment of the second model. A crude estimate shows that the average dust cover resting on more solid ground of lunar rocks might possibly have a thickness of approximately 0.5 meters.  相似文献   

Mother-of-pearl clouds and their problems     

Dr. Heinz Dieterichs 《Pure and Applied Geophysics》1950,16(3-4):128-132

Summary At first the results of the investigations on mother-of-pearl clounds are summarized. In the second section fit methods are suggested in order to further research.

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Zusammenfassung Zunächst werden die Forschungsergebnisse über Perlmutterwolken zusammengefasst. Im zweiten Teil werden geeignete Methoden zur weiteren Forschung vorgeschlagen.

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Post-Chippewa oxygen isotope record from Cowles Bog, southern Lake Michigan basin     

Barry B. Miller  Michael J. S. Tevesz  Jodie E. Smith 《Journal of Paleolimnology》1997,18(3):299-305

Previous studies of sediments and molluscs recovered from vibracores at Cowles Bog, a fen located in the Indiana Dunes National Lakeshore, along the south shore of Lake Michigan, reveal long and short term water level fluctuations during the last 6000 years. Low water events are indicated by zones of organic detritus, in which occasionally, iron oxide and calcium carbonate nodules, as well as selenite crystals have been precipitated. Oxygen isotope data from aragonitic shells of the gastropod Amnicola limosa (Say) collected from a sediment core provide a record of Middle to Late Holocene environmental changes for the fen. These data are in good agreement with previous interpretations of water level fluctuations based on changes in lithology and molluscan faunal abundance and composition. Below 366 cm the molluscan record is either absent or represented by shell fragments. The condition of shells in this interval suggests that the molluscs may have been exposed to subaerial weathering and reworking of older Holocene lake sediments, possibly during the low water Chippewa phase in the Lake Michigan basin (10000 YBP to 6000 YBP). Above 366 cm the core is characterized by a well preserved molluscan fauna. Relatively light isotopic values for the interval between 366 cm to 300 cm correlate with the transition from non-fossiliferous sands, peat and diamict to silty marl and calcareous sand, with a molluscan fauna dominated by taxa associated with permanent water bodies. The event producing these alterations, the Nipissing Transgression, marks a change from subaerial to permanent lacustrine conditions that were not characterized by high net evaporation. Evidence for another series of environmental changes occurs between 284 cm and 198 cm. This evidence includes the: (1) appearance of aquatic molluscs at 280 cm that are associated with water bodies subject to significant seasonal water level changes; (2) intermittent accumulations of iron oxide nodules, calcium carbonate nodules, and organic layers interbedded with crudely horizontal layers of fine, calcareous, sand, suggesting periodic water level oscillations; (3) onset of major excursions in the oxygen isotopic values between 260 cm to 198 cm. Relatively high ¹⁸O (PDB) values, possibly indicating evaporative enrichment of the water, correlate with a prominent shell debris layer at a depth of about 235 cm. Taken together, this evidence suggests that the core site was in the process of becoming isolated from Lake Michigan. This isolation occurred during a series of low water events during the later part of the Nipissing Transgression.  相似文献   

ON THE WAVELENGTH DEPENDENCY (AND ITS VARIATIONS) OF THE RATIO DISK-AVERAGED TO DISK-CENTER INTENSITY,F/I 0 (λλ0.385 TO 10 µm)     

Neckel  Heinz 《Solar physics》1997,171(2):257-268

In the whole wavelength range, 0.385 to 10.0 µm, the ratios F/I ₀ of disk-averaged intensity F to disk-center intensity I ₀ follow very closely the simple relation F/I ₀ = 0.975 - 0.091^-1 - 0.00024^-5. The residuals exhibit a well-defined structure with minima and maxima in the order of± 5 × 10^-3 , which reflect the wavelength-dependency of the source function B(,) and the continuous absorption coefficient . The fact that the scatter of the coefficients of the relevant limb-darkening functions is usually much larger than the scatter of the F/I ₀ ratios seems to confirm the occurrence of limb-darkening variations, which however leave the F/I ₀ ratios almost unchanged. Nevertheless, minor differences between different observations, which concern the details in the wavelength-dependency of the F/I ₀ residuals, seem to indicate that even the F/I ₀ ratios undergo minor variations.  相似文献   

Water temperature dynamics and heat transport in a typical Japanese river     

Makoto Higashino  Heinz G. Stefan 《Environmental Earth Sciences》2016,75(7):618

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Hydrothermal remobilisation around a deformed and remobilised komatiite-hosted Ni-Cu-(PGE) deposit,Sarah’s Find,Agnew Wiluna greenstone belt,Yilgarn Craton,Western Australia     

Margaux Le Vaillant  Ahmad Saleem  Stephen J. Barnes  Marco L. Fiorentini  John Miller  Steve Beresford  Caroline Perring 《Mineralium Deposita》2016,51(3):369-388

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Improved assessment of biodegradation extent and prediction of petroleum quality     

Rouven Elias  Andrea Vieth  Angelo Riva  Brian Horsfield  Heinz Wilkes 《Organic Geochemistry》2007,38(12):2111-2130

Biodegradation of crude oil causes volumetrically important compositional changes, which lead to significant deterioration in quality, in particular during the early stages of alteration. To better understand these effects we focussed on a detailed assessment of light to moderate levels of alteration. We investigated a suite of 40 crude oil samples from five different petroleum systems to evaluate the extent of alteration occurring in reservoirs. Based on a comprehensive geochemical characterization, five individual crude oil sequences were defined, where compositional variability is mainly due to microbial activity in the reservoir. In particular, samples from the Gullfaks field (offshore Norway) and from a petroleum system offshore Angola illustrate that conventional molecular biodegradation parameters, such as the Pr/n-C₁₇ and Ph/n-C₁₈ alkane ratios are not suitable for defining the extent of biodegradation in petroleum reservoirs. Here, we suggest a new molecular biodegradation parameter, the degradative loss, that can be used to quantify depletion in individual crude oil constituents. The approach allows improved assessment of the extent of biodegradation in crude oil samples by means of the mean degradative loss. It is demonstrated that crude oil quality, as assessed from API gravity, can be predicted directly from the molecular composition of crude oils. Our data clearly indicate that the degradation patterns of light hydrocarbons and n-alkanes differ in different petroleum systems. This suggests that microbial communities are different and therefore generate different molecular degradation patterns which have to be evaluated individually for each system.  相似文献   

A deep reef in deep trouble     

C. Menza  M. Kendall  C. Rogers  J. Miller 《Continental Shelf Research》2007

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An analysis of soil moisture dynamics using multi-year data from a network of micrometeorological observation sites   总被引：4，自引：0，他引：4  

Gretchen R. Miller  Dennis D. Baldocchi  Beverly E. Law  Tilden Meyers 《Advances in water resources》2007

Soil moisture data, obtained from four AmeriFlux sites in the US, were examined using an ecohydrological framework. Sites were selected for the analysis to provide a range of plant functional type, climate, soil particle size distribution, and time series of data spanning a minimum of two growing seasons. Soil moisture trends revealed the importance of measuring water content at several depths throughout the rooting zone; soil moisture at the surface (0–10 cm) was approximately 20–30% less than that at 50–60 cm. A modified soil moisture dynamics model was used to generate soil moisture probability density functions at each site. Model calibration results demonstrated that the commonly used soil matric potential values for finding the vegetation stress point and field content may not be appropriate, particularly for vegetation adapted to a water-controlled environment. Projections of future soil moisture patterns suggest that two of the four sites will become severely stressed by climate change induced alterations to the precipitation regime.  相似文献   

Radar rainfall estimation for flash flood forecasting in small urban watersheds     

James A. Smith  Mary Lynn Baeck  Katherine L. Meierdiercks  Andrew J. Miller  Witold F. Krajewski 《Advances in water resources》2007

Radar rainfall estimation for flash flood forecasting in small, urban catchments is examined through analyses of radar, rain gage and discharge observations from the 14.3 km² Dead Run drainage basin in Baltimore County, Maryland. The flash flood forecasting problem pushes the envelope of rainfall estimation to time and space scales that are commensurate with the scales at which the fundamental governing laws of land surface processes are derived. Analyses of radar rainfall estimates are based on volume scan WSR-88D reflectivity observations for 36 storms during the period 2003–2005. Gage-radar analyses show large spatial variability of storm total rainfall over the 14.3 km² basin for flash flood producing storms. The ability to capture the detailed spatial variation of rainfall for flash flood producing storms by WSR-88D rainfall estimates varies markedly from event to event. As spatial scale decreases from the 14.3 km² scale of the Dead Run watershed to 1 km² (and the characteristic time scale of flash flood producing rainfall decreases from 1 h to 15 min) the predictability of flash flood response from WSR-88D rainfall estimates decreases sharply. Storm to storm variability of multiplicative bias in storm total rainfall estimates is a dominant element of the error structure of radar rainfall estimates, and it varies systematically over the warm season and with flood magnitude. Analyses of the 7 July 2004 and 28 June 2005 storms illustrate microphysical and dynamical controls on radar estimation error for extreme flash flood producing storms.  相似文献