Identifying and removing structural biases in climate models with history matching     

Williamson  Daniel  Blaker  Adam T.  Hampton  Charlotte  Salter  James 《Climate Dynamics》2015,45(5-6):1299-1324

Climate Dynamics - We describe the method of history matching, a method currently used to help quantify parametric uncertainty in climate models, and argue for its use in identifying and removing...  相似文献   

Temporal Evolution of the Solar-Wind Electron Core Density at Solar Minimum by Correlating SWEA Measurements from STEREO A and B     

A. Opitz  J.-A. Sauvaud  A. Fedorov  P. Wurz  J. G. Luhmann  B. Lavraud  C. T. Russell  P. Kellogg  C. Briand  P. Henri  D. M. Malaspina  P. Louarn  D. W. Curtis  E. Penou  R. Karrer  A. B. Galvin  D. E. Larson  I. Dandouras  P. Schroeder 《Solar physics》2010,266(2):369-377

The twin STEREO spacecraft provide a unique tool to study the temporal evolution of the solar-wind properties in the ecliptic since their longitudinal separation increases with time. We derive the characteristic temporal variations at ～?1 AU between two different plasma parcels ejected from the same solar source by excluding the spatial variations from our datasets. As part of the onboard IMPACT instrument suite, the SWEA electron experiment provides the solar-wind electron core density at two different heliospheric vantage points. We analyze these density datasets between March and August 2007 and find typical solar minimum conditions. After adjusting for the theoretical time lag between the two spacecraft, we compare the two density datasets. We find that their correlation decreases as the time difference increases between two ejections. The correlation coefficient is about 0.80 for a time lag of a half day and 0.65 for two days. These correlation coefficients from the electron core density are somewhat lower than the ones from the proton bulk velocity obtained in an earlier study, though they are still high enough to consider the solar wind as persistent after two days. These quantitative results reflect the variability of the solar-wind properties in space and time, and they might serve as input for solar-wind models.  相似文献   

Coupled convection and tidal dissipation in Europa’s ice shell     

Lijie Han  Adam P. Showman 《Icarus》2010,207(2):834-505

We performed 2D numerical simulations of oscillatory tidal flexing to study the interrelationship between tidal dissipation (calculated using the Maxwell model) and a heterogeneous temperature structure in Europa’s ice shell. Our 2D simulations show that, if the temperature is spatially uniform, the tidal dissipation rate peaks when the Maxwell time is close to the tidal period, consistent with previous studies. The tidal dissipation rate in a convective plume encased in a different background temperature depends on both the plume and background temperature. At a fixed background temperature, the dissipation increases strongly with plume temperature at low temperatures, peaks, and then decreases with temperature near the melting point when a melting-temperature viscosity of 10¹³ Pa s is used; however, the peak occurs at significantly higher temperature in this heterogeneous case than in a homogeneous medium for equivalent rheology. For constant plume temperature, the dissipation rate in a plume decreases as the surrounding temperature increases; plumes that are warmer than their surroundings can exhibit enhanced heating not only relative to their surroundings but relative to the Maxwell-model prediction for a homogeneous medium at the plume temperature. These results have important implications for thermal feedbacks in Europa’s ice shell.To self-consistently determine how convection interacts with tidal heating that is correctly calculated from the time-evolving heterogeneous temperature field, we coupled viscoelastic simulations of oscillatory tidal flexing (using Tekton) to long-term simulations of the convective evolution (using ConMan). Our simulations show that the tidal dissipation rate resulting from heterogeneous temperature can have a strong impact on thermal convection in Europa’s ice shell. Temperatures within upwelling plumes are greatly enhanced and can reach the melting temperature under plausible tidal-flexing amplitude for Europa. A pre-existing fracture zone (at least 6 km deep) promotes the concentration of tidal dissipation (up to ∼20 times more than that in the surroundings), leading to lithospheric thinning. This supports the idea that spatially variable tidal dissipation could lead locally to high temperatures, partial melting, and play an important role in the formation of ridges, chaos, or other features.  相似文献   

A submillimetre survey of the kinematics of the Perseus molecular cloud – I. Data     

Emily I. Curtis  John S. Richer  Jane V. Buckle 《Monthly notices of the Royal Astronomical Society》2010,401(1):455-472

We present submillimetre observations of the   J = 3 → 2  rotational transition of ¹²CO, ¹³CO and C¹⁸O across over 600 arcmin² of the Perseus molecular cloud, undertaken with the Heterodyne Array Receiver Programme (HARP), a new array spectrograph on the James Clerk Maxwell Telescope. The data encompass four regions of the cloud, containing the largest clusters of dust continuum condensations: NGC 1333, IC348, L1448 and L1455. A new procedure to remove striping artefacts from the raw HARP data is introduced. We compare the maps to those of the dust continuum emission mapped with the Submillimetre Common-User Bolometer Array (SCUBA; Hatchell et al.) and the positions of starless and protostellar cores (Hatchell et al.). No straightforward correlation is found between the masses of each region derived from the HARP CO and SCUBA data, underlining the care that must be exercised when comparing masses of the same object derived from different tracers. From the ¹³CO/C¹⁸O line ratio the relative abundance of the two species  ([¹³CO]/[C¹⁸O]∼ 7)  and their opacities (typically τ is 0.02–0.22 and 0.15–1.52 for the C¹⁸O and ¹³CO gas, respectively) are calculated. C¹⁸O is optically thin nearly everywhere, increasing in opacity towards star-forming cores but not beyond  τ₁₈∼ 0.9  . Assuming the ¹²CO gas is optically thick, we compute its excitation temperature, T _ex (around 8–30 K), which has little correlation with estimates of the dust temperature.  相似文献   

Climate and cultural history of the Northeastern Yucatan Peninsula, Quintana Roo, Mexico     

D. A. Hodell  M. Brenner  J. H. Curtis 《Climatic change》2007,83(1-2):215-240

We inferred the Holocene paleoclimate history of the northeastern Yucatan Peninsula, Mexico, by studying stratigraphic variations in stable isotopes (δ ¹⁸O and δ ¹³C) and lithologic properties (organic matter and carbonate content) in sediment cores taken in 6.3 and 16.2 m of water from Lake Punta Laguna. We present a simple model to explain the lithologic and isotopic variations, and discuss the inferred paleoclimate history in terms of its relation to ancient Maya cultural development. We find evidence for lower lake level and drier climate at about the same time as each major discontinuity in Maya cultural history: Preclassic Abandonment (150–250 A.D.), Maya Hiatus (534 to 593 A.D.), Terminal Classic Collapse (750–1050 A.D.), and Postclassic Abandonment (mid-fifteenth century). Although these broad temporal correlations suggest climate played a role in Maya cultural evolution, chronological uncertainties preclude a detailed analysis of climate changes and archaeologically documented cultural transformations.  相似文献   

Efficacy of a multi-metric fish index as an analysis tool for the transitional fish component of the Water Framework Directive     

Coates S  Waugh A  Anwar A  Robson M 《Marine pollution bulletin》2007,55(1-6):225-240

The WFD has introduced an international commitment to assess the ecological status of transitional waters (TWs), within which fish communities are a key biological monitoring component. The Transitional Fish Classification Index (TFCI) outlined in this paper uses 10 ecological measures to analyse fish populations caught from various ecological niches using a variety of gear types within the Thames estuary. These reach and method-specific communities are then compared to a reference population created from a 'healthy' population from TWs of a similar type. The results indicate a progressive downstream increase the quality of fish communities, consistent with previous work; variation between methods can be accounted for by gear selectivity. Overall, the TFCI is an effective communication tool for converting ecological information into an easily understood format for managers, policy makers and the general public.  相似文献   

Comparison of P- and S-waves velocities estimated from Biot-Gassmann and Kuster-Toksöz models with results obtained from acoustic wavetrains interpretation     

Maria BałA  Adam Cichy 《Acta Geophysica》2007,55(2):222-230

Kuster-Toksöz and Biot-Gassmann models for estimating velocities of longitudinal and shear waves on the basis of well-logging data were analysed. P-wave and S-wave velocity models are crucial for interpretation of seismic data. Discussed models enable determination with quite good accuracy, in some cases higher than the acoustic full wavetrains interpretation. Because velocity strongly depends on lithology and saturation of pore space, the selection of parameters of rock matrix, hydrocarbons and formation waters has a strong effect on the quality of velocities estimation.  相似文献   

Realizable accessibility: evaluating the reliability of public transit accessibility using high-resolution real-time data     

Liu  Luyu  Porr  Adam  Miller  Harvey J. 《Journal of Geographical Systems》2023,25(3):429-451

Journal of Geographical Systems - The widespread availability of high spatial and temporal resolution public transit data is improving the measurement and analysis of public transit-based...  相似文献   

Diatoms indicate that calcium decline,not acidification,explains recent cladoceran assemblage changes in south-central Ontario softwater lakes     

Jennifer L. Barrow  Adam Jeziorski  Kathleen M. Rühland  Kristopher R. Hadley  John P. Smol 《Journal of Paleolimnology》2014,52(1-2):61-75

In recent decades, softwater lakes across Canada have experienced a wide array of anthropogenic influences, with acidification and climate warming of particular concern. Here, we compare modern and pre-industrial sedimentary diatom assemblages from 36 softwater lakes located on the Canadian Shield in south-central Ontario to determine whether lake acidification or reduced calcium availability was the main stressor responsible for recent declines in Ca-sensitive cladoceran taxa. Regional surveys of south-central Ontario water chemistry have identified the pH recovery of many formerly acidified lakes, and our fossil diatom-inferred pH analyses indicate that modern lakewater pH in the 36 study lakes is similar to (or higher than) pre-industrial levels, with diatom assemblages from both time periods dominated by taxa with similar pH preferences. In addition, modern diatom assemblages compared to pre-industrial assemblages contained higher relative abundances of planktonic diatom taxa (e.g. Asterionella formosa and the Discostella stelligera complex) and lower relative abundances of heavily silicified diatoms (e.g. Aulacoseira taxa) and benthic fragilarioid taxa. These taxonomic shifts are consistent with warming-induced changes in lake properties including a longer ice-free period, decreased wind speed and/or increased thermal stability. We conclude that recent changes observed within the cladoceran assemblages of these lakes are not a response to acidification, but are likely a consequence of Ca declines. In addition, our data suggest that regional climate warming is now responsible for the diatom changes observed in this region.  相似文献   

Two rapid assays for screening of patulin biodegradation     

S. A. I. Wright  D. V. de Felice  G. Ianiri  C. Pinedo-Rivilla  F. De Curtis  R. Castoria 《International Journal of Environmental Science and Technology》2014,11(5):1387-1398

The mycotoxin patulin is produced by the blue mould pathogen Penicillium expansum in rotting apples during postharvest storage. Patulin is toxic to a wide range of organisms, including humans, animals, fungi and bacteria. Wash water from apple packing and processing houses often harbours patulin and fungal spores, which can contaminate the environment. Ubiquitous epiphytic yeasts, such as Rhodosporidium kratochvilovae strain LS11 which is a biocontrol agent of P. expansum in apples, have the capacity to resist the toxicity of patulin and to biodegrade it. Two non-toxic products are formed. One is desoxypatulinic acid. The aim of the work was to develop rapid, high-throughput bioassays for monitoring patulin degradation in multiple samples. Escherichia coli was highly sensitive to patulin, but insensitive to desoxypatulinic acid. This was utilized to develop a detection test for patulin, replacing time-consuming thin layer chromatography or high-performance liquid chromatography. Two assays for patulin degradation were developed, one in liquid medium and the other in semi-solid medium. Both assays allow the contemporary screening of a large number of samples. The liquid medium assay utilizes 96-well microtiter plates and was optimized for using a minimum of patulin. The semi-solid medium assay has the added advantage of slowing down the biodegradation, which allows the study and isolation of transient degradation products. The two assays are complementary and have several areas of utilization, from screening a bank of microorganisms for biodegradation ability to the study of biodegradation pathways.  相似文献