Evaluation and comparison of spatial interpolators II

The performance of several variations on ordinary kriging and inverse distance estimators is evaluated. Mean squared errors (MSE) were calculated for estimates made on multiple resamplings from five exhaustive data bases representing two distinctly different types of estimation problem. Ordinary kriging, when performed with variograms estimated from the sample data, was more robust than inverse-distance methods to the type of estimation problem, and to the choice of estimation parameters such as number of neighbors.Notice: Although the research described in this article has been funded in part by the United States Environmental Protection Agency through Cooperative Agreement CR818526 to the Harry Reid Center for Environmental Studies, University of Nevada-Las Vegas, it has not been subjected to Agency review. Therefore it does not necessarily reflect the views of the Agency. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

Geochemical constraints on magma processes in a peralkaline system: The Paisano volcano,west Texas

Major and trace element data for a sequence of peralkaline silicic lavas and pyroclastic flows, exposed in the caldera wall of the Paisano volcano, west Texas, document systematic fractional crystallization during magmatic evolution and an open system, magma mixing event in the upper parts of the sequence. Stratigraphically lowest flows are comendite and comenditic quartz trachyte lavas and ash flow tufts. Overlying these units is a trachyte with compositional, textural and mineralogical features indicating that it is the product of magma-mixing; similar flows occur in other parts of the volcano at the same stratigraphic level. This composite trachyte is considered to be a mixture of mugearitic or mafic trachytic magma, derived from a similar source region which yielded the earlier caldera wall flows. Trace element concentrations of the post-trachyte comenditic quartz trachyte lavas suggest they were erupted from a chamber whose magma was diluted by an influx of mugearitic or mafic trachytic magma during a magma mixing event.Rayleigh fractionation calculations show that the comendites and comenditic quartz trachytes can be derived from a parental mugearite magma by 88% to 93% fractionation of dominantly plagioclase and alkali feldspar, with lesser amounts of clinopyroxene, magnetite and apatite. Zircon was not a significant fractionating phase. The composition, mineralogy and depth of the source region(s) which generated these magmas cannot be constrained from the present data set.     

Forecasting errors: The importance of the decision-making context

This article demonstrates the importance of context on forecast errors. It de J.scribes the development of an unrealistic transportation planning forecast for Denver, Colorado, noting its influence on air quality planning for Denver. The importance of two contextual features, procedural rationality and conflict of interest, to the introduction of error is discussed. The case described implies that different decision-making contexts define different rules of rationality, and substantive rationality may not fit the rules. The type of context and not necessarily a code of ethics will determine this.     

Intra-field variability of scalar flux densities across a transition between a desert and an irrigated potato field

This paper reports on measurements of sensible and latent heat and CO₂ fluxes made over an irrigated potato field, growing next to a patch of desert. The study was conducted using two eddy correlation systems. One measurement system was located within the equilibrium boundary layer 800 m downwind from the edge of the potato field. The other measurement system was mobile and was placed at various downwind positions to probe the horizontal transition of vertical scalar fluxes. Latent (LE) and sensible (H) heat fluxes, measured at 4 m above the surface, exhibited marked variations with downwind distance over the field. Only after the fetch to height ratio exceeded 75 to 1 didLE andH become invariant with downwind distance. When latent and sensible heat fluxes were measured upwind of this threshold, significant advection of humidity-deficit occurred, causing a vertical flux divergence ofH andLE.The measured fluxes of momentum, heat, and moisture were compared with predictions from a second-order closure two-dimensional atmospheric boundary layer model. There is good agreement between measurements and model predictions. A soil-plant-atmosphere model was used to examine nonlinear feedbacks between humidity-deficits, stomatal conductance and evaporation. Data interpretation with this model revealed that the advection of hot dry air did not enhance surface evaporation rates near the upwind edge of the potato field, because of negative feedbacks among stomatal conductance, humidity-deficits, andLE. This finding is consistent with results from several recent studies.     

Short polarity intervals within the Matuyama: transitional field records from hydraulic piston cored sediments from the North Atlantic

Detailed sampling of two short magnetozones within the Matuyama Chronozone recorded at DSDP Site 609 (49.86°N, 335.77°E) confirms that one, the Cobb Mountain Subchronozone (1.12 Ma), is a very short, full normal polarity interval and that the other, the older interval, is a record of a geomagnetic excursion which occurred at approximately 1.55 Ma. The Cobb Mountain Subchron lasted approximately 25,000 years, one third the duration of the Jaramillo Subchron. The normal polarity interval is bounded by two transition zones which document an antisymmetry in the sequence of directions in the reverse to normal and normal to reverse polarity transitions. We interpret the antisymmetry as reflecting a dependence upon the sense of the reversal, without significant changes in the relative contributions of non-dipole terms. The polarity interval recorded at 1.55 Ma lasted only 8,800 years with what may be regarded as full polarity directions observed across only 3 cm of stratigraphic section. This feature is interpreted as an excursion of the geomagnetic field and appears to be correlative with the Gilsa Subchron. Similarities between the transition bounding these two magnetozones suggest that these features occur as the result of the same process or triggering mechanisms in the earth's outer core.     

Orthodoxy and creativity in theories of mountain building before 1922

In the 1870s, theories of mountain building emerged from little more than speculation to inference based on a growing body of observation and documentation. This coincided with abandonment of models stressing uplift, and their replacement, in the new orthodoxy, by models in which earth contraction led to lateral compression in its outer shell. Nevertheless, perceived weaknesses in this model gave impetus to new theories, some emphasizing primary vertical movement, and others continental displacement or subcrustal flow. The rebel theories added to the understanding of earth processes in important ways, by drawing attention to the weaknesses in the prevailing orthodoxy. But, in 1922, the complete answer remained out of reach.

---

Zusammenfassung Die siebziger Jahre des vorigen Jahrhunderts brachten den Anfang von wissenschaftlich fundierten Theorien der Gebirgsbildung. Diese Zeit sah auch den Übergang von Erhebungstheorien zur neuen Lehrmeinung, nach welcher Erdkontraktion zu lateralen Drucken in der Außenhülle der Erde führte. Erkannte Schwächen dieses Modells führten jedoch zu neuen Gegentheorien, von denen einige primäre Vertikalbewegungen in den Vordergrund stellten, während andere Kontinentalverschiebung oder Unterströmungen als den Motor der Gebirgsbildung sahen. Diese Gegentheorien haben den Fortschritt der Erdwissenschaften gefördert, indem sie auf Schwächen der herrschenden Lehrmeinung aufmerksam machten. Aber selbst zu Argands Zeit war ein völlig befriedigendes Modell noch gar nicht erreichbar.

---

Résumé C'est dans les années 1870–1880 que commençaient à s'établir les premières théories vraiment scientifiques de l'orogenèse. C'était la décade qui marqua l'abandon des théories à base de soulèvement et le début du règne de la nouvelle orthodoxie d'après laquelle la contraction de la terre mène à la compression latérale d'une pellicule extérieure. Néansmoins, certaines faiblesses du nouveau modèle servaient d'élan à des théories rebelles dont quelques-unes soulignaient l'importance des soulèvements primaires, tandisque d'autres cherchaient le moteur de l'orogenèse dans la dérive des continents ou dans des courants dans une masse quasi-fluide subcrustale. Ces théories rebelles ont avancé la science en soulignant les faiblesses de l'orthodoxie. En fin de compte, une solution complètement satisfaisante ne paraissait pas encore pouvoir être atteinte à l'époque d'Argand.

---

70- . , . , , , , . , . .

     

Characteristics of air flow above and within soybean canopies

Air flow was observed above and within canopies of a number of kinds of soybeans. The Clark cultivar and two isolines of the Harosoy cultivar were studied in 1979 and 1980, respectively. Wind speed above the canopy was measured with cup anemometers. Heated thermistor anemometers were used to measure air flow within the canopy. Above-canopy air flow was characterized in terms of the zero-plane displacement (d), roughness parameter (z _o) and drag coefficient (C _d). d and z _o were dependent on canopy height but were independent of friction velocity in the range 0.55 to 0.75 m s^?1 · C _d for the various canopies ranged from 0.027 to 0.035. Greater C _d values were measured over an erectophile canopy than over a planophile canopy. C _d was not measurably affected by differences in leaf pubescence. Within-canopy wind profiles were measured at two locations: within and between rows. The wind profile was characterized by a region of great wind shear in the upper canopy and by a region of relatively weak wind shear in the middle canopy. Considerable spatial variability in wind speed was evident, however. This result has significant implications for canopy flow modeling efforts aimed at evaluating transport in the canopy. In the lower canopy, wind speed within a row increased with depth whereas wind speed between two rows decreased with depth. The wind speeds at the two locations tended to converge to a common value at a height near 0.10 m. The attenuation of within-canopy air flow was stronger in canopies with greater foliage density. Canopy flow attenuation seemed to decrease with increasing wind speed, suggesting that high winds distorted the shape of the canopy in such a manner that the penetration of wind into the canopy increased.