Statistical decadal predictions for sea surface temperatures: a benchmark for dynamical GCM predictions   总被引：1，自引：1，他引：0  

Chun Kit Ho  Ed Hawkins  Len Shaffrey  Fiona M. Underwood 《Climate Dynamics》2013,41(3-4):917-935

Accurate decadal climate predictions could be used to inform adaptation actions to a changing climate. The skill of such predictions from initialised dynamical global climate models (GCMs) may be assessed by comparing with predictions from statistical models which are based solely on historical observations. This paper presents two benchmark statistical models for predicting both the radiatively forced trend and internal variability of annual mean sea surface temperatures (SSTs) on a decadal timescale based on the gridded observation data set HadISST. For both statistical models, the trend related to radiative forcing is modelled using a linear regression of SST time series at each grid box on the time series of equivalent global mean atmospheric CO₂ concentration. The residual internal variability is then modelled by (1) a first-order autoregressive model (AR1) and (2) a constructed analogue model (CA). From the verification of 46 retrospective forecasts with start years from 1960 to 2005, the correlation coefficient for anomaly forecasts using trend with AR1 is greater than 0.7 over parts of extra-tropical North Atlantic, the Indian Ocean and western Pacific. This is primarily related to the prediction of the forced trend. More importantly, both CA and AR1 give skillful predictions of the internal variability of SSTs in the subpolar gyre region over the far North Atlantic for lead time of 2–5 years, with correlation coefficients greater than 0.5. For the subpolar gyre and parts of the South Atlantic, CA is superior to AR1 for lead time of 6–9 years. These statistical forecasts are also compared with ensemble mean retrospective forecasts by DePreSys, an initialised GCM. DePreSys is found to outperform the statistical models over large parts of North Atlantic for lead times of 2–5 years and 6–9 years, however trend with AR1 is generally superior to DePreSys in the North Atlantic Current region, while trend with CA is superior to DePreSys in parts of South Atlantic for lead time of 6–9 years. These findings encourage further development of benchmark statistical decadal prediction models, and methods to combine different predictions.  相似文献   

Real-time multi-model decadal climate predictions   总被引：1，自引：1，他引：0  

Doug M. Smith  Adam A. Scaife  George J. Boer  Mihaela Caian  Francisco J. Doblas-Reyes  Virginie Guemas  Ed Hawkins  Wilco Hazeleger  Leon Hermanson  Chun Kit Ho  Masayoshi Ishii  Viatcheslav Kharin  Masahide Kimoto  Ben Kirtman  Judith Lean  Daniela Matei  William J. Merryfield  Wolfgang A. Müller  Holger Pohlmann  Anthony Rosati  Bert Wouters  Klaus Wyser 《Climate Dynamics》2013,41(11-12):2875-2888

We present the first climate prediction of the coming decade made with multiple models, initialized with prior observations. This prediction accrues from an international activity to exchange decadal predictions in near real-time, in order to assess differences and similarities, provide a consensus view to prevent over-confidence in forecasts from any single model, and establish current collective capability. We stress that the forecast is experimental, since the skill of the multi-model system is as yet unknown. Nevertheless, the forecast systems used here are based on models that have undergone rigorous evaluation and individually have been evaluated for forecast skill. Moreover, it is important to publish forecasts to enable open evaluation, and to provide a focus on climate change in the coming decade. Initialized forecasts of the year 2011 agree well with observations, with a pattern correlation of 0.62 compared to 0.31 for uninitialized projections. In particular, the forecast correctly predicted La Niña in the Pacific, and warm conditions in the north Atlantic and USA. A similar pattern is predicted for 2012 but with a weaker La Niña. Indices of Atlantic multi-decadal variability and Pacific decadal variability show no signal beyond climatology after 2015, while temperature in the Niño3 region is predicted to warm slightly by about 0.5 °C over the coming decade. However, uncertainties are large for individual years and initialization has little impact beyond the first 4 years in most regions. Relative to uninitialized forecasts, initialized forecasts are significantly warmer in the north Atlantic sub-polar gyre and cooler in the north Pacific throughout the decade. They are also significantly cooler in the global average and over most land and ocean regions out to several years ahead. However, in the absence of volcanic eruptions, global temperature is predicted to continue to rise, with each year from 2013 onwards having a 50 % chance of exceeding the current observed record. Verification of these forecasts will provide an important opportunity to test the performance of models and our understanding and knowledge of the drivers of climate change.  相似文献   

Newly formed massive stars: are they good for the neighborhood?     

Ed Churchwell 《Astrophysics and Space Science》1995,224(1-2):157-171

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Reconstruction of RHESSI Solar Flare Images with a Forward Fitting Method     

Aschwanden  Markus J.  Schmahl  Ed  Team  the RHESSI 《Solar physics》2002,210(1-2):193-211

We describe a forward-fitting method that has been developed to reconstruct hard X-ray images of solar flares from the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI), a Fourier imager with rotation-modulated collimators that was launched on 5 February 2002. The forward-fitting method is based on geometric models that represent a spatial map by a superposition of multiple source structures, which are quantified by circular gaussians (4 parameters per source), elliptical gaussians (6 parameters), or curved ellipticals (7 parameters), designed to characterize real solar flare hard X-ray maps with a minimum number of geometric elements. We describe and demonstrate the use of the forward-fitting algorithm. We perform some 500 simulations of rotation-modulated time profiles of the 9 RHESSI detectors, based on single and multiple source structures, and perform their image reconstruction. We quantify the fidelity of the image reconstruction, as function of photon statistics, and the accuracy of retrieved source positions, widths, and fluxes. We outline applications for which the forward-fitting code is most suitable, such as measurements of the energy-dependent altitude of energy loss near the limb, or footpoint separation during flares. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1022469811115  相似文献   

New Data on the Middle–Late Holocene Evolution of Vegetation Cover in the Northern Baikal Region     

Vershinin  K. E.  Osipov  Ed. Yu. 《Doklady Earth Sciences》2019,488(1):1076-1080

Doklady Earth Sciences - A continuous peat bog section from a barely accessible mid-mountain area in the northwestern Baikal region has been obtained for the first time. The materials were studied...  相似文献   

Pseudostalaktiten und Verwandtes     

Raphael Ed. Liesegang 《International Journal of Earth Sciences》1914,5(4):241-246

Ohne Zusammenfassung  相似文献   

Beiträge zur Geochemie     

R. Ed. Liesegang 《International Journal of Earth Sciences》1913,4(5-6):404-408

Ohne Zusammenfassung  相似文献   

Begriff und Bedeutung der Intrusionstektonik     

Franz Ed. Suess 《International Journal of Earth Sciences》1927,18(2):149-154

Ohne Zusammenfassung  相似文献   

Scattered ground‐roll attenuation using model‐driven interferometry          下载免费PDF全文

Phil Bilsby  Lee West  Ed Kragh  John Quigley 《Geophysical Prospecting》2015,63(1):116-132

Scattered ground roll is a type of noise observed in land seismic data that can be particularly difficult to suppress. Typically, this type of noise cannot be removed using conventional velocity‐based filters. In this paper, we discuss a model‐driven form of seismic interferometry that allows suppression of scattered ground‐roll noise in land seismic data. The conventional cross‐correlate and stack interferometry approach results in scattered noise estimates between two receiver locations (i.e. as if one of the receivers had been replaced by a source). For noise suppression, this requires that each source we wish to attenuate the noise from is co‐located with a receiver. The model‐driven form differs, as the use of a simple model in place of one of the inputs for interferometry allows the scattered noise estimate to be made between a source and a receiver. This allows the method to be more flexible, as co‐location of sources and receivers is not required, and the method can be applied to data sets with a variety of different acquisition geometries. A simple plane‐wave model is used, allowing the method to remain relatively data driven, with weighting factors for the plane waves determined using a least‐squares solution. Using a number of both synthetic and real two‐dimensional (2D) and three‐dimensional (3D) land seismic data sets, we show that this model‐driven approach provides effective results, allowing suppression of scattered ground‐roll noise without having an adverse effect on the underlying signal.  相似文献   

Uncertainty estimation for operational ocean forecast products—a multi-model ensemble for the North Sea and the Baltic Sea     

Inga Golbeck  Xin Li  Frank Janssen  Thorger Brüning  Jacob W. Nielsen  Vibeke Huess  Johan Söderkvist  Bjarne Büchmann  Simo-Matti Siiriä  Olga Vähä-Piikkiö  Bruce Hackett  Nils M. Kristensen  Harald Engedahl  Ed Blockley  Alistair Sellar  Priidik Lagemaa  Jose Ozer  Sebastien Legrand  Patrik Ljungemyr  Lars Axell 《Ocean Dynamics》2015,65(12):1603-1631

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