Changes in a rocky shore community: An evaluation of monitoring

The basic aim of this study was to record the changes in the communities on a moderately exposed rocky shore by a programme of repeated non-destructive sampling (‘monitoring’) and to determine the causes of these changes. Possible causative factors were investigated by the combined approach of analysing detailed sea-temperature and meteorological data for the period of the study and establishing manipulative field experiments.Fixed quadrats (2 m by 1 m) at three levels were visited at 6–8 weekly intervals for 30 months and the abundance and spatial pattern of major species assessed. In the ‘High’ quadrat the balance between Fucus spiralis and F. vesiculosus changed, and an outburst of ephemeral algae occurred following a decline in overall canopy cover. In the ‘Mid’ quadrat F. vesiculosus decreased considerably from its initial cover and virtually disappeared by the end of the study. In the ‘Low’ quadrat F. vesiculosus increased from being absent to comprising 20% of the canopy, whilst Semmibalanus (= Balanus) balanoides and ‘understorey’ algae decreased in cover. Actinia equina, Nucella lapillus and Patella vulgata showed marked changes in number at all levels where they occurred.Only certain of these changes could be attributed to the physical environment—most were biologically controlled. For example, manipulative experiments showed that the blooms of ephemeral algae and the decline of Patella in the high-shore quadrat, and the decline of Actinia in the mid-shore quadrat, were due to decreases in the fucoid canopy. These canopy changes were, in turn, the result of biological cycles which are characteristic of these communities. However, even with the support of manipulative experiments, it was not possible to account for (or predict) all of the observed natural changes. The extent of these fluctuations poses a serious obstacle to the recognition of any but very gross pollution-induced effects. The conclusion must be that the monitoring of rocky shores as a means of detecting and measuring pollution is likely to be an unproductive investment of time and resources.     

A verification framework for interannual-to-decadal predictions experiments

Decadal predictions have a high profile in the climate science community and beyond, yet very little is known about their skill. Nor is there any agreed protocol for estimating their skill. This paper proposes a sound and coordinated framework for verification of decadal hindcast experiments. The framework is illustrated for decadal hindcasts tailored to meet the requirements and specifications of CMIP5 (Coupled Model Intercomparison Project phase 5). The chosen metrics address key questions about the information content in initialized decadal hindcasts. These questions are: (1) Do the initial conditions in the hindcasts lead to more accurate predictions of the climate, compared to un-initialized climate change projections? and (2) Is the prediction model’s ensemble spread an appropriate representation of forecast uncertainty on average? The first question is addressed through deterministic metrics that compare the initialized and uninitialized hindcasts. The second question is addressed through a probabilistic metric applied to the initialized hindcasts and comparing different ways to ascribe forecast uncertainty. Verification is advocated at smoothed regional scales that can illuminate broad areas of predictability, as well as at the grid scale, since many users of the decadal prediction experiments who feed the climate data into applications or decision models will use the data at grid scale, or downscale it to even higher resolution. An overall statement on skill of CMIP5 decadal hindcasts is not the aim of this paper. The results presented are only illustrative of the framework, which would enable such studies. However, broad conclusions that are beginning to emerge from the CMIP5 results include (1) Most predictability at the interannual-to-decadal scale, relative to climatological averages, comes from external forcing, particularly for temperature; (2) though moderate, additional skill is added by the initial conditions over what is imparted by external forcing alone; however, the impact of initialization may result in overall worse predictions in some regions than provided by uninitialized climate change projections; (3) limited hindcast records and the dearth of climate-quality observational data impede our ability to quantify expected skill as well as model biases; and (4) as is common to seasonal-to-interannual model predictions, the spread of the ensemble members is not necessarily a good representation of forecast uncertainty. The authors recommend that this framework be adopted to serve as a starting point to compare prediction quality across prediction systems. The framework can provide a baseline against which future improvements can be quantified. The framework also provides guidance on the use of these model predictions, which differ in fundamental ways from the climate change projections that much of the community has become familiar with, including adjustment of mean and conditional biases, and consideration of how to best approach forecast uncertainty.     

R. E. (Ted) Munn — Founding editor; a mini-biography

Ted Munn founded Boundary-Layer Meteorology in 1970 and served as Editor for 75 volumes over a 25 year period. This short article briefly reviews Ted's scientific career with the Atmospheric Environment Service (of Canada), the International Institute for Applied Systems Analysis in Austria and with the Institute of Environmental Studies at the University of Toronto, and as editor of this journal.     

Inclined pipe vesicles as indicators of flow direction in basalts: A critical appraisal

Inclined pipe vesicles and stretched vesicles near the base of basalt flows have long been regarded as reliable flow-direction indicators. However, attempts to use such structures in the Santa Rosa Basalt of Southern California to determine regional flow patterns, paleoslope, and source of eruption yielded inconclusive and contradictory results. Orientations of 1070 vesicles at 37 localities were obtained directions of inclination from vertical were plotted on circular histograms. At any specific locality vesicle orientations typically are normally distributed through a 40–60 degree sector. Commonly a pronounced maximum lies within a 20–40 degree sector. Even at localities having bimodal or trimodal distribution patterns, most vesicles plot within a 90 degree sector. The frequency distribution of oriented vesicles at individual localities strongly suggests a limited direction of flow and implies a source in the opposite direction. Comparison of such «flow directions» from locality to locality within the same flow, however, yielded highly divergent results over short distances. Likewise, comparison of directions from different flows yielded results ranging from parallel to diametrically opposed. Composite circular histograms from three small mesas censisting of thin, flat-lying flows showed little apparent preferred direction of vesicle inclination. Possible reasons for the highly divergent readings include sub-flow surface irregularities, turbulent rather than laminar flow, and/or convection in the lava during cooling. Although inclined vesicles may well indicate motion in a flow, their use for determination of flow directions and for regional paleogeographic interpretations is questionable.     

Kleinraummeteorologische Studien im Federseegebiet in Strahlungsnächten

Zusammenfassung Die vorliegende Studie befaßt sich mit den meteorologischen Vorgängen in einer extrem stabil aufgebauten Kaltluft, wie sie sich in Strahlungsnächten in einem abgeschlossenen Becken mit ebener, horizontaler Talsohle von einigen Kilometern Ausdehnung und im wesentlichen einheitlichem Untergrund einer Moorlandschaft herausbildet.Untersucht wird in erster Linie das Eigenleben der so abgeschlossenen Luftmasse. Dabei zeigt sich, daß der Zustand eines ruhenden Kaltluftsees zumeist erst im Endstadium des nächtlichen Prozesses näherungsweise erreicht wird. Während des größten Teiles der Nacht kommen vielmehr überraschend lebhafte und weitreichende angenähert horizontale Bewegungen leicht zustande, die sich im thermischen Gefüge wie in der Windstruktur kundtun und in dem Verhalten der Nebel- und Dunstfelder sichtbar werden. Unter der Wirkung von Schwerkraft, Druckgefälle und Reibung entstehen einfache Gleitvorgänge, Schaukelbewegungen, fortschreitende Wellen und Seiches, die in einzelnen Beispielen beschrieben werden. Ähnlich wie in der Großraummeteorologie bilden sich durch das quantenhafte Verhalten der Energieumsätze Luftkörperindividuen, deren Deformation hier einfacheren Gesetzen folgt. Trotz ihrer sehr verschiedenen Größenordnung von einigen Dekametern bis zu mehreren Kilometern Ausdehnung bei geringer vertikaler Mächtigkeit zeigen sie auf ihrer Vorderseite einheitlich die Form des vonW. Schmidt in Modellversuchen gefundenen Böenkopfes.Der Einfluß höherer Luftschichten auf die stabilisierte Bodenkaltluft äußert sich in aufgeprägten Wellen und Frendlufteinschüben. Das Beispiel eines nächtlichen Wärmeeinbruchs aus der Höhe wird eingehend beschrieben.

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Summary The present study deals with the meteorological processes in an extremely stable cold air, formed in clear nights in a confined basin with a plane, horizontal basis extended for some kilometres, and with an essentially uniform ground in a fen-country.In the first place the proper life of the so limited air is studied. It becomes evident, that the state of a resting lake of cold air generally is approximately reached but in the final phase of the night-time process. Moreover, for the greater part of the night surprising active and extended movements of nearly horizontal course easily occur, becoming evident in the structure of wind and temperature stratification and also visible in the behaviour of fog and haze fields. Produced by gravitation, pressure gradient and friction, simple gliding and swinging motions, proceeding waves and seiches result which are described in single examples. Corresponding to the large scale meteorology individual air bodies form by the quantum-like behaviour of energy transformations. Their deformation in this case however, takes course according to simpler laws. In spite of their much various magnitude of the dimensions of some decametres up to several kilometres, while being of small vertical extension they show in their fore part in all cases the shape of a Böenkopf as found byW. Schmidt by model experiments.The influence of upper atmospheric layers on the stable cold air near the ground manifests itself by impressed waves and by influxes of heterogeneous air. An example of a nocturnal invasion of warm air from aloft is described in detail.

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Résumé Cette étude traite des processus météorologiques dans un air froid d'une stratification extrêmement stable, qui se développent pendant des nuits claires dans un bassin fermé, ayant une base plane et horizontale, d'une étendue de quelques km, et recouverte par le sol essentiellement homogène d'une région marécageuse.C'est surtout la «vie propre» de cette masse d'air limitée qui est étudiée. Il se trouve que, le plus souvent, l'état d'un «lac immobile d'air froid» n'est atteint approximativement qu'à la fin du processus nocturne. Pendant la plus grande partie de la nuit, se produisent au contraire facilement des mouvements presque horizontaux étonnamment actifs et étendus, qui se manifestent dans la structure thermique et du vent, et qui deviennent visibles par le comportement des couches de brouillard et de brume. De simples processus de glissement, des oscillations, des ondes progressives et des seiches se forment sous l'influence de la gravitation, du gradient de pression et du frottement; ils sont décrits par des exemples particuliers. Comme cela se produit dans la météorologie à grande échelle, il se forme des corps atmosphériques individuels à la suite du comportement en quanta des transformations d'énergie. Leur déformation a lieu cependant selon des lois plus simples. En dépit de leur étendue très variable allant de quelques decamètres à plusieurs km, et leur épaisseur peu considérable, ils montrent tous à leur partie antérieure la forme d'un «Böenkopf», pareil à celui queW. Schmidt a trouvé à la suite de ses expériences qu'il fit avec des modèles.L'influence des couches supérieures de l'atmosphère sur l'air froid stable au sol se manifeste par l'impression d'ondes et par des apports d'air étranger. On décrit ensuite en détail une invasion nocturne d'air chaud depuis les couches supérieures.

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Mit 13 Textabbildungen.

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Herrn Prof. Dr.W. Peppler, zum 70. Geburtstag.     

Visual classification of very fine-grained sediments: Evaluation through univariate and multivariate statistics

Classifying very fine-grained rocks through fabric elements provides information about depositional environments, but is subject to the biases of visual taxonomy. To evaluate the statistical significance of an empirical classification of very fine-grained rocks, samples from Devonian shales in four cored wells in West Virginia and Virginia were measured for 15 variables: quartz, illite, pyrite and expandable clays determined by X-ray diffraction; total sulfur, organic content, inorganic carbon, matrix density, bulk density, porosity, silt, as well as density, sonic travel time, resistivity, and -ray response measured from well logs. The four lithologic types comprised: (1) sharply banded shale, (2) thinly laminated shale, (3) lenticularly laminated shale, and (4) nonbanded shale. Univariate and multivariate analyses of variance showed that the lithologic classification reflects significant differences for the variables measured, difference that can be detected independently of stratigraphic effects. Little-known statistical methods found useful in this work included: the multivariate analysis of variance with more than one effect, simultaneous plotting of samples and variables on canonical variates, and the use of parametric ANOVA and MANOVA on ranked data.     

A new population of brown dwarfs

In this paper we report the first results from a survey for low-mass stars and brown dwarfs, based on a photographic stack of around 100 Schmidt plates. This survey extends photographic searches by about 2 mag, and covers an area of 25 deg². Some 30 faint objects with large R − I colours were selected for further study, and were found to have very strong molecular absorption in their spectra, but only moderately red infrared colours. Five of these stars were selected for a parallax programme; three of these were found to be at a distance of around 45 pc, implying a very low luminosity. On the basis of their luminosity alone it is clear that these stars are field brown dwarfs, and we discuss their likely evolutionary status in the context of current models of low-mass stellar evolution.     

Binary coefficients: A theoretical and empirical study

Binary coefficients can be assigned to several categories on the basis of algebraic and conceptual properties. The phi coefficient of association is related algebraically to the chi-square statistic for 2-by-2 contingency tables, and use of this coefficient in cluster analysis permits the objective, nonarbitrary partitioning of objects among groups on the basis of previously selected levels of significant, positive association. Similarity, matching, and distance coefficients possess neither conceptual nor operational statistical meaning for many geological data sets. The weighted pair group method and flexible clustering strategy may give an overly conservative partitioning of objects among groups. Clustering by the unweighted pair group method, using the phi coefficient, is recommended for the analysis of biostratigraphic and paleoecologic presence—absence data.     

Petrology and geochemistry of basaltic rocks of the Lau Basin

The Lau Basin is a marginal sea, located between the Tonga and Lau Ridges, in the southwestern Pacific. The basin is on the “inner” or concave side of the Tonga Trench-Arc system and is situated above the deep seismic zone dipping westward from the Tonga Trench. The Tonga Trench-Arc system is undoubtedly located above a zone of crustal shortening as evidenced by the deep seismicity and vulcanism. However, the geological and geophysical data give strong support to the contention that the Lau Basin has formed by crustal dilation.Rocks dredged from ridges and seamounts in the basin are sub-alkaline basalt. The average major element composition of least altered samples is: SiO₂ 48.8%, TiO₂ 1.2%, K₂O 0.18%, P₂O₅ 0.08%, H₂O+ 0.30%, Fe^III/Fe^II = 0.26,CaO/Al₂O₃ = 0.77. The data for Lau Basin basalt (LBB) show close similarity to data of typical oceanic ridge basalt (ORB). Trace element abundances (ppm): Ni 160, Cr 390, Sr 100, Ba < 31, Rb < 1 also resemble ORB values. K/Rb in a least altered and unfractionated sample is 860, Ba/Sr is 0.1, Ba/Rb is 8. Strontium isotope data show the only marked variance from ORB chemistry with LBB values ranging from ⁸⁷Sr/⁸⁶Sr=0.7020 to 0.7051. The low Sr abundances in the samples suggest the possibility of crustal Sr contamination to explain the radiogenic Sr enrichment. An alternate possibility is that the mantle source rocks were enriched in ⁸⁷Sr. Variation within dredge hauls and between dredge sites may be explained by low-pressure fractional crystallization of magmas separated from the mantle at about 50 km depth.The basin probably began to open in middle to late Miocene time either by the disruption of a single andesitic island arc by splitting along its axis or by dilation of the area between two closely spaced concentric arcs. Mantle counterflow in the asthenosphere above the downgoing oceanic lithosphere slab is the probable driving force for dilation and has provided a continuous supply of parent material for the basalt of the basin floor.