On the contribution of local feedback mechanisms to the range of climate sensitivity in two GCM ensembles   总被引：3，自引：15，他引：3  

M. J. Webb  C. A. Senior  D. M. H. Sexton  W. J. Ingram  K. D. Williams  M. A. Ringer  B. J. McAvaney  R. Colman  B. J. Soden  R. Gudgel  T. Knutson  S. Emori  T. Ogura  Y. Tsushima  N. Andronova  B. Li  I. Musat  S. Bony  K. E. Taylor 《Climate Dynamics》2006,27(1):17-38

Global and local feedback analysis techniques have been applied to two ensembles of mixed layer equilibrium CO₂ doubling climate change experiments, from the CFMIP (Cloud Feedback Model Intercomparison Project) and QUMP (Quantifying Uncertainty in Model Predictions) projects. Neither of these new ensembles shows evidence of a statistically significant change in the ensemble mean or variance in global mean climate sensitivity when compared with the results from the mixed layer models quoted in the Third Assessment Report of the IPCC. Global mean feedback analysis of these two ensembles confirms the large contribution made by inter-model differences in cloud feedbacks to those in climate sensitivity in earlier studies; net cloud feedbacks are responsible for 66% of the inter-model variance in the total feedback in the CFMIP ensemble and 85% in the QUMP ensemble. The ensemble mean global feedback components are all statistically indistinguishable between the two ensembles, except for the clear-sky shortwave feedback which is stronger in the CFMIP ensemble. While ensemble variances of the shortwave cloud feedback and both clear-sky feedback terms are larger in CFMIP, there is considerable overlap in the cloud feedback ranges; QUMP spans 80% or more of the CFMIP ranges in longwave and shortwave cloud feedback. We introduce a local cloud feedback classification system which distinguishes different types of cloud feedbacks on the basis of the relative strengths of their longwave and shortwave components, and interpret these in terms of responses of different cloud types diagnosed by the International Satellite Cloud Climatology Project simulator. In the CFMIP ensemble, areas where low-top cloud changes constitute the largest cloud response are responsible for 59% of the contribution from cloud feedback to the variance in the total feedback. A similar figure is found for the QUMP ensemble. Areas of positive low cloud feedback (associated with reductions in low level cloud amount) contribute most to this figure in the CFMIP ensemble, while areas of negative cloud feedback (associated with increases in low level cloud amount and optical thickness) contribute most in QUMP. Classes associated with high-top cloud feedbacks are responsible for 33 and 20% of the cloud feedback contribution in CFMIP and QUMP, respectively, while classes where no particular cloud type stands out are responsible for 8 and 21%.  相似文献   

Foreword to this Special Issue of “Ore Geology Reviews”     

Hilton Ingram 《Ore Geology Reviews》2008,34(1-2)

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Shipping noise in a dynamic sea: a case study of grey seals in the Celtic Sea     

F. Chen  G.I. Shapiro  K.A. Bennett  S.N. Ingram  D. Thompson  C. Vincent  D.J.F. Russell  C.B. Embling 《Marine pollution bulletin》2017,114(1):372-383

Shipping noise is a threat to marine wildlife. Grey seals are benthic foragers, and thus experience acoustic noise throughout the water column, which makes them a good model species for a case study of the potential impacts of shipping noise. We used ship track data from the Celtic Sea, seal track data and a coupled ocean-acoustic modelling system to assess the noise exposure of grey seals along their tracks. It was found that the animals experience step changes in sound levels up to ~ 20 dB at a frequency of 125 Hz, and ~ 10 dB on average over 10–1000 Hz when they dive through the thermocline, particularly during summer. Our results showed large seasonal differences in the noise level experienced by the seals. These results reveal the actual noise exposure by the animals and could help in marine spatial planning.  相似文献   

Interannual variability of sea‐ice cover in Hudson bay,Baffin bay and the Labrador sea     

Jia Wang  Lawrence A. Mysak  R. Grant Ingram 《大气与海洋》2013,51(2):421-447

Abstract

The spatial and temporal relationships between subarctic Canadian sea‐ice cover and atmospheric forcing are investigated by analysing sea‐ice concentration, sea‐level pressure and surface air temperature data from 1953 to 1988. The sea‐ice anomalies in Hudson Bay, Baffin Bay and the Labrador Sea are found to be related to the North Atlantic Oscillation (NAO) and the Southern Oscillation (SO). Through a spatial Student's i‐test and a Monte Carlo simulation, it is found that sea‐ice cover in both Hudson Bay and the Baffin Bay‐Labrador Sea region responds to a Low/Wet episode of the SO (defined as the period when the SO index becomes negative) mainly in summer. In this case, the sea‐ice cover has a large positive anomaly that starts in summer and continues through to autumn. The ice anomaly is attributed to the negative anomalies in the regional surface air temperature record during the summer and autumn when the Low/Wet episode is developing. During strong winter westerly wind events of the NAO, the Baffin Bay‐Labrador Sea ice cover in winter and spring has a positive anomaly due to the associated negative anomaly in surface air temperature. During the years in which strong westerly NAO and Low/Wet SO events occur simultaneously (as in 1972/73 and 1982/83), the sea ice is found to have large positive anomalies in the study region; in particular, such anomalies occurred for a major portion of one of the two years. A spectral analysis shows that sea‐ice fluctuations in the Baffin Bay‐Labrador Sea region respond to the SO and surface air temperature at about 1.7‐, 5‐ and 10‐year periods. In addition, a noticeable sea‐ice change was found (i.e. more polynyas occurred) around the time of the so‐called “climate jump” during the early 1960s. Data on ice thickness and on ice‐melt dates from Hudson Bay are also used to verify some of the above findings.  相似文献   

Numerical investigations of wave overtopping at coastal structures     

D.M. Ingram  F. Gao  D.M. Causon  C.G. Mingham  P. Troch 《Coastal Engineering》2009

Under the numerical modelling work package of the EU funded CLASH project, the time accurate, free surface capturing, incompressible Navier–Stokes solver AMAZON-SC has been applied to study impulsive wave overtopping at Samphire Hoe, near Dover in the United Kingdom. The simulations show that the overtopping process on this vertical, sheet pile, seawall is dominated by impulsive, aerated, near vertical overtopping jets. In order to perform the simulations AMAZON-SC has been extended to incorporate an isotropic porosity model and for validation purposes the solver has been applied to study overtopping of a low crested sea dike and a 10:1 battered wall. The results obtained for the battered wall and Samphire Hoe tests are in good agreement both with predicted overtopping discharges calculated using the UK overtopping manual and with available experimental results.  相似文献   

AgClimate: a case study in participatory decision support system development     

N. E. Breuer  V. E. Cabrera  K. T. Ingram  K. Broad  P. E. Hildebrand 《Climatic change》2008,87(3-4):385-403

Potential economic benefit exists from the use of seasonal climate forecasts in agriculture. To assess potential end user attitudes toward and interests in climate data, and to provide inputs from users to the development of decision support tools, we conducted a series of surveys. Survey results affected the design, development, and enhancement of AgClimate, a web-based decision support system for minimizing climate risks to agriculture. The overall process is an example of how decision makers can participate in the research process, thereby improving the value and relevance of research products such as decision support systems.  相似文献   

A step-response approach for predicting and understanding non-linear precipitation changes   总被引：1，自引：1，他引：0  

Peter Good  William Ingram  F. Hugo Lambert  Jason A. Lowe  Jonathan M. Gregory  Mark J. Webb  Mark A. Ringer  Peili Wu 《Climate Dynamics》2012,39(12):2789-2803

Future changes in precipitation represent one of the most important and uncertain possible effects of future climate change. We demonstrate a new approach based on idealised CO₂ step-change general circulation model (GCM) experiments, and test it using the HadCM3 GCM. The approach has two purposes: to help understand GCM projections, and to build and test a fast simple model for precipitation projections under a wide range of forcing scenarios. Overall, we find that the CO₂ step experiments contain much information that is relevant to transient projections, but that is more easily extracted due to the idealised experimental design. We find that the temporary acceleration of global-mean precipitation in this GCM following CO₂ ramp-down cannot be fully explained simply using linear responses to CO₂ and temperature. A more complete explanation can be achieved with an additional term representing interaction between CO₂ and temperature effects. Energy budget analysis of this term is dominated by clear-sky outgoing long-wave radiation (CSOLR) and sensible heating, but cloud and short-wave terms also contribute. The dominant CSOLR interaction is attributable to increased CO₂ raising the mean emission level to colder altitudes, which reduces the rate of increase of OLR with warming. This behaviour can be reproduced by our simple model. On regional scales, we compare our approach with linear ‘pattern-scaling’ (scaling regional responses by global-mean temperature change). In regions where our model predicts linear change, pattern-scaling works equally well. In some regions, however, substantial deviations from linear scaling with global-mean temperature are found, and our simple model provides more accurate projections. The idealised experiments reveal a complex pattern of non-linear behaviour. There are likely to be a range of controlling physical mechanisms, different from those dominating the global-mean response, requiring focussed investigation for individual regions, and in other GCMs.  相似文献   

Governmentality and security in the US President’s Emergency Plan for AIDS Relief (PEPFAR)     

Alan Ingram 《Geoforum》2010,41(4):607-616

This article offers a critical theoretical exploration of the US President’s Emergency Plan for AIDS Relief (PEPFAR). The article examines the background to PEPFAR and its reauthorization in Washington DC in 2008 through the conceptual lens of governmentality. Building on existing work, it interprets PEPFAR as a programme for securing the welfare of populations. It also qualifies and extends this work in the following ways. Rather than representing a break with the history of geopolitics, it argues that PEPFAR emerged out of accommodations between geopolitics and governmentality. This point is developed through two takes on geopolitics, first in terms of the projection of sovereign power, and second in terms of articulations between PEPFAR and geopolitical economies of global health. The article suggests, first, that the geopolitics of sovereign power shaped the timing, scale and form of PEPFAR, and second, that PEPFAR articulated with geopolitical economies of global health through its mobilization of US-based corporations, non-governmental and faith-based organizations. The article extends existing work by examining the role of critical mobilizations in shaping PEPFAR, both in relation to questions of political economy and the contentious politics of life. Reflecting on the politics of global health, it considers the prospects for using ideas of security and the international response to HIV/AIDS as stepping stones towards the development of broad-based health systems.  相似文献   

Ion microprobe measurement of strontium isotopes in calcium carbonate with application to salmon otoliths     

Peter K. Weber  Charles R. Bacon  B. Lynn Ingram 《Geochimica et cosmochimica acta》2005,69(5):1225-1239

The ion microprobe has the capability to generate high resolution, high precision isotopic measurements, but analysis of the isotopic composition of strontium, as measured by the ⁸⁷Sr/⁸⁶Sr ratio, has been hindered by isobaric interferences. Here we report the first high precision measurements of ⁸⁷Sr/⁸⁶Sr by ion microprobe in calcium carbonate samples with moderate Sr concentrations. We use the high mass resolving power (7000 to 9000 M.R.P.) of the SHRIMP-RG ion microprobe in combination with its high transmission to reduce the number of interfering species while maintaining sufficiently high count rates for precise isotopic measurements. The isobaric interferences are characterized by peak modeling and repeated analyses of standards. We demonstrate that by sample-standard bracketing, ⁸⁷Sr/⁸⁶Sr ratios can be measured in inorganic and biogenic carbonates with Sr concentrations between 400 and 1500 ppm with ∼2‰ external precision (2σ) for a single analysis, and subpermil external precision with repeated analyses. Explicit correction for isobaric interferences (peak-stripping) is found to be less accurate and precise than sample-standard bracketing. Spatial resolution is ∼25 μm laterally and 2 μm deep for a single analysis, consuming on the order of 2 ng of material. The method is tested on otoliths from salmon to demonstrate its accuracy and utility. In these growth-banded aragonitic structures, one-week temporal resolution can be achieved. The analytical method should be applicable to other calcium carbonate samples with similar Sr concentrations.  相似文献   

Weather Forecasts are for Wimps: Why Water Resource Managers Do Not Use Climate Forecasts   总被引：3，自引：3，他引：0  

Steve Rayner  Denise Lach  Helen Ingram 《Climatic change》2005,69(2-3):197-227

Short-term climate forecasting offers the promise of improved hydrologic management strategies. However, water resource managers in the United States have proven reluctant to incorporate them in decision making. While managers usually cite poor reliability of the forecasts as the reason for this, they are seldom able to demonstrate knowledge of the actual performance of forecasts or to consistently articulate the level of reliability that they would require. Analysis of three case studies in California, the Pacific Northwest, and metro Washington DC identifies institutional reasons that appear to lie behind managers reluctance to use the forecasts. These include traditional reliance on large built infrastructure, organizational conservatism and complexity, mismatch of temporal and spatial scales of forecasts to management needs, political disincentives to innovation, and regulatory constraints. The paper concludes that wider acceptance of the forecasts will depend on their being incorporated in existing organizational routines and industrial codes and practices, as well as changes in management incentives to innovation. Finer spatial resolution of forecasts and the regional integration of multi-agency functions would also enhance their usability.The title of this article is taken from an advertising slogan for the Oldsmobile Bravura SUV.  相似文献