The Continuous Plankton Recorder: concepts and history, from Plankton Indicator to undulating recorders

Alister Hardy conceived the Continuous Plankton Recorder (CPR) survey in the 1920s as a means of mapping near-surface plankton in space and time, interpreting the changing fortunes of the fisheries and relating plankton changes to hydrometeorology and climatic change. The seed he planted has grown to become the most extensive long-term survey of marine organisms in the world and the breadth of his vision becomes ever more apparent. The survey has now run for over 70 years and its value increases with every passing decade. Operating from ‘ships of opportunity’ the machines used are robust, reliable and easy to handle. Wherever possible, all the sampling and analytical methods have not been changed to maintain the consistency of the time series. Computerisation and the development of new statistical approaches have increased our ability to handle the large quantities of information generated and enhance the sensitivity of the data analyses. This overview, based on almost 900 papers, recounts the various phases in the history of the survey. It starts with the Indicator Survey (1921–1934), the deployment of the first CPR on the Discovery Expedition (1924–1927) and the early CPR survey in the North Sea (1931–1939). The survey reopened in 1946 after the Second World War and expanded across the North Atlantic to North America from 1959. Taxonomic studies were initiated and an emphasis was placed on patterns of distribution, which were seen to reflect the varying oceanographic conditions. The years 1968–1976 saw further expansion with operations even in the American Great Lakes, publication of a Plankton Atlas and initial evidence for a downward trend in plankton biomass. At about this time electronic instrumentation was attached to CPRs to make additional measurements and work was started on the development of a new generation of undulating Continuous Plankton and Environmental Recorders (CPERs). In 1976 the survey moved to Plymouth. Scientific priorities in the UK changed in the subsequent decade and funding became more difficult to secure even though some of the CPR papers being published at the time are now regarded as classics in plankton ecology. In 1988 the UK Natural Environment Research Council (NERC) decided to close the survey. An international rescue operation led to the creation of the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) in 1990, which has continued with consortium funding from a number of countries, and from 1999 again included NERC. The scientific rationale of the survey has gained credibility as concern over climate change and other anthropogenic effects has grown and as the key role that plankton plays as an indicator of large-scale environmental conditions becomes ever more apparent. Recently, the survey became an integral component of the Global Ocean Observation System (GOOS) and expanded into the North Pacific. It plays a complementary role in many large international and multidisciplinary projects and is providing inspiration, advice and support to daughter surveys elsewhere in the world. At the start of a new millennium, Hardy’s vision from the 1920s is a powerful driving force not just in international biological oceanography, but in global environmental science.     

Time domain modelling of the transient asymmetric flooding of Ro-Ro ships

This work aims at contributing to improve knowledge on transient asymmetric flooding through theoretical and experimental research. First, a time domain theoretical model of ship motions and flooding is described. Results from experimental work are presented evidencing that transient asymmetric flooding may cause the capsizing of a Ro-Ro shaped barge. The theoretical model is used to predict the capsize of the Ro-Ro shaped barge. Reasonable agreement between experimental and theoretical results was found. Finally, a review of the European Gateway accident is given and the theoretical model is applied to the study of this type of accident. The conclusion is that this theoretical model, together with an accurate modelling of the flooding of machinery compartments, reproduces successfully the capsizing of the European Gateway due to transient asymmetric flooding. Therefore, the internal arrangement of Ro-Ro ships should be carefully studied at the design stage in order to avoid this phenomenon.     

An experimental method for determining the frequency-dependent added mass and added mass moment of inertia for a floating body in heave and pitch motions

Most of the existing relevant materials have been obtained from experiments, in which evaluating the added mass at the resonant frequency corresponding to the peak of a frequency-response curve obtained from the “forced” vibration analysis is the most popular technique. In this paper, a simple experimental method was presented where the “free” vibration responses instead of the “forced” ones were used to determine the values of m_ah and I_ap. The main part of the experimental system is composed of a floating body (model) and a spring–shaft shaker. The “free” vibration of this main part was induced by imposing on it an initial displacement (and/or an initial velocity), and from the time histories of displacements information such as the “damped” natural frequencies, damping ratios, sectional added mass coefficients (C_V and C_P) were obtained. Since the displacements of the spring–shaft shaker are “translational” and those of the floating body due to pitch motions are “angular”, a technique for the transformation between the associated parameters of the two components of the main part was presented.     

Prediction of UT1–UTC,LOD and AAM χ<Subscript>3</Subscript> by combination of least-squares and multivariate stochastic methods

This article presents the application of a multivariate prediction technique for predicting universal time (UT1–UTC), length of day (LOD) and the axial component of atmospheric angular momentum (AAM χ ₃). The multivariate predictions of LOD and UT1–UTC are generated by means of the combination of (1) least-squares (LS) extrapolation of models for annual, semiannual, 18.6-year, 9.3-year oscillations and for the linear trend, and (2) multivariate autoregressive (MAR) stochastic prediction of LS residuals (LS + MAR). The MAR technique enables the use of the AAM χ ₃ time-series as the explanatory variable for the computation of LOD or UT1–UTC predictions. In order to evaluate the performance of this approach, two other prediction schemes are also applied: (1) LS extrapolation, (2) combination of LS extrapolation and univariate autoregressive (AR) prediction of LS residuals (LS + AR). The multivariate predictions of AAM χ ₃ data, however, are computed as a combination of the extrapolation of the LS model for annual and semiannual oscillations and the LS + MAR. The AAM χ ₃ predictions are also compared with LS extrapolation and LS + AR prediction. It is shown that the predictions of LOD and UT1–UTC based on LS + MAR taking into account the axial component of AAM are more accurate than the predictions of LOD and UT1–UTC based on LS extrapolation or on LS + AR. In particular, the UT1–UTC predictions based on LS + MAR during El Niño/La Niña events exhibit considerably smaller prediction errors than those calculated by means of LS or LS + AR. The AAM χ ₃ time-series is predicted using LS + MAR with higher accuracy than applying LS extrapolation itself in the case of medium-term predictions (up to 100 days in the future). However, the predictions of AAM χ ₃ reveal the best accuracy for LS + AR.     

GPS CORS系统中NTRIP传输技术的应用研究

NTRIP是一种播发实时差分定位改正信息的IP协议。本文讨论了NTRIP的组成、工作原理,并给出一个应用实例。     

Long-term prediction of intermediate depth earthquakes in the southern Aegean region based on a time-predictable model

Repeat times of strong intermediate depth (60 km h 180 km) earthquakes have been determined by the use of instrumental and historical data for six seismogenic sources in the Benioff zone of the southern Aegean area. For four of these sources, at least two interevent times (three mainshocks) are available for each source. By using the repeat times for these four sources, the following relation has been determined: logT _t = 0.20M _min + 0.19M _p +a, whereT _t is the repeat time (in years),M _min the surface wave magnitude of the smallest earthquake considered,M _p the magnitude of the preceding mainshock and a parameter which varies from source to source. A multilinear correlation coefficient equal to 0.91 was determined for this relation, which indicates that the time predictable model holds to a satisfactory degree for the strong mainshocks of intermediate focal depth in the southern Aegean.By assuming that the ratioT/T _t, whereT is the observed andT _t the calculated repeat time, follows a lognormal distribution, the conditional probabilities for the occurrence of strong (M _s 6.5) and very strong (M _s 7.5) earthquakes during the period 1991–2001 in these four seismogenic sources have been calculated. These probabilities are very high (P > 0.9) for the strong and high (P > 0.5) for the very strong intermediate depth earthquakes which occur in the three sources of the shallower (h < 100 km) part of the Benioff zone where coupling occurs between the front parts of the Mediterranean lithosphere (downgoing) and the Aegean lithosphere.     

Modeling the cyclic swelling pressure of mudrock using artificial neural networks

The stochastic nature of the cyclic swelling behavior of mudrock and its dependence on a large number of interdependent parameters was modeled using Time Delay Neural Networks (TDNNs). This method has facilitated predicting cyclic swelling pressure with an acceptable level of accuracy where developing a general mathematical model is almost impossible. A number of total pressure cells between shotcrete and concrete walls of the powerhouse cavern at Masjed–Soleiman Hydroelectric Powerhouse Project, South of Iran, where mudrock outcrops, confirmed a cyclic swelling pressure on the lining since 1999. In several locations, small cracks are generated which has raised doubts about long term stability of the powerhouse structure. This necessitated a study for predicting future swelling pressure. Considering the complexity of the interdependent parameters in this problem, TDNNs proved to be a powerful tool. The results of this modeling are presented in this paper.     

Estimating the minimum in-stream flow requirements via wetted perimeter method based on curvature and slope techniques

Under the assumptions of triangular cross section channel and uniform stable flow, an analytical solution of the minimum ecological in-stream flow requirement (MEIFR) is deduced. Based on the analytical solution, the uncertainty of the wetted perimeter method is analyzed by comparing the two techniques for the determination of the critical point on the relationship curve between wetted perimeter, P and discharge, Q. It is clearly shown that the results of MEIFR based on curvature technique (corresponding to the maximum curvature) and slope technique (slope being 1) are significantly different. On the P-Q curve, the slope of the critical point with the maximum curvature is 0.39 and the MEIFR varied prominently with the change of the slope threshold. This indicates that if a certain value of the slope threshold is not available for slope technique, curvature technique may be a better choice. By applying the analytical solution of MEIFR in the losing rivers of the Western Route South-to-North Water Transfer Project in China, the MEIFR value via curvature technique is 2.5%-23.7% of the multi-year average annual discharge, while that for slope technique is 11%-105.7%. General conclusions would rely on the more detailed research for all kinds of cross-sections.     

Reconstructing hydrological variability from testate amoebae analysis in Carpathian peatlands

Peatlands offer the potential for high resolution records of water balance over Holocene timescales, yet this potential is under-exploited in many areas of the world. Within Europe, peatlands are mostly confined to areas north of 55° N, but several areas of southern and eastern Europe contain small peatlands which may be suitable for palaeoclimatic reconstruction. In this paper we test the potential of peatlands in the Carpathian region for deriving quantified estimates of water table changes using testate amoebae analysis. A training set for palaeohydrological reconstruction from testate amoebae assemblages was obtained by collecting surface samples from 13 peatlands, including 9 from Hungary and 4 from Transylvania (Romania). Using a simple measure of mean annual water tables estimated from staining of PVC tape, we found that some peatlands were heavily influenced by runoff and groundwater, and were therefore not suitable as modern analogues of ombrotrophic climatically sensitive sites. The relationship between the testate amoebae assemblages in the modern samples and the environmental variables was explored using CCA. The CCA biplot showed that the most important variables are depth to water table and moisture content, confirming that hydrology is a key control on taxon distribution. pH was a secondary gradient. A transfer function for % moisture and depth to water table was established and applied to fossil assemblages from a sequence from Fenyves-tető, Transylvania, Romania. The reconstructed water table shows a number of variations which have parallels with other palaeoclimatic records from Europe and the North Atlantic prominent phases of higher water tables are associated with the periods 8000–8300 cal BP, 3000–2500 cal BP and after 600 cal BP. We suggest that these were periods of particular intensification of westerly airflow which affected eastern Europe as well as western and central Europe.     

A comparison of chironomid biostratigraphy from Lake Vuolep Njakajaure with vegetation, lake-level, and climate changes in Abisko National Park, Sweden

Chironomid remains from the sediment of Lake Vuolep Njakajaure reflect limnological conditions resulting from changing climate and vegetation throughout the Holocene, but do not strictly follow accepted climate trends or the vegetation history based on regional pollen and macrofossil analyses. Chironomid community changes appear to be influenced by organic nutrient input from the surrounding catchment vegetation and lake hydrology, both of which are indirectly responding to some combination of climate change, hypolimnetic oxygen concentration, and changes in basin morphology. The chironomid-based quantitative mean July air-temperature reconstruction differs from other regional quantitative records; this discrepancy is likely related to limnological conditions particular to Lake Vuolep Njakajaure. Comparison of a northern Swedish temperature transfer function and one from western Canada reveals differences in the mean July air-temperature optima of several common taxa, suggesting that the existing conservative estimates of Holocene climate change in northern Sweden may be underestimated due to the limited temperature gradient captured by the Swedish training set.