Decadal climate predictions in the North Atlantic region: The role of ocean heat transport

The possibility of credible climate forecasts for several years ahead - on the decadal time scale - has received considerable public and economic attention. Scientific studies quantify the credibility of such forecasts by evaluating the average predictive quality (skill) over the last 50-60 years (in so-called hindcasts). Decadal hindcasts of surface temperatures were shown to be on average particularly skillful in the North Atlantic region. However, the reason for the high skill of these hindcasts is still unclear. Mean- while, North Atlantic sea surface temperatures (SSTs) are on the decadal time scale strongly influenced by subpolar ocean heat transport (OHT) variability. I here connect OHT variability and SST predictability and test whether the knowledge of the strength of subpolar OHT at the beginning of a single SST forecast can improve its credibility. By using initialized global climate simulations of the twentieth century, I confirm pre- vious studies in that OHT variability influences SST variability for 3-10 years. A char- acteristic SST pattern of warm anomalies in the northeast Atlantic and cold anomalies in the Gulf Stream region emerges after strong OHT phases and vice versa. This pat- tern originates from persistently growing upper ocean heat content anomalies that arise from Southward propagating OHT anomalies in the North Atlantic. Extending previ- ous work, I analyze strong and weak OHT phases at 50◦N separately. This reveals an asymmetry between strong and weak phases of ocean heat transport: When subpolar OHT is strong, North Atlantic SSTs show stronger and more persistent decadal anoma- lies than when subpolar OHT is weak. For the first time I show that the hindcast skill of northeast Atlantic SSTs 3-10 years ahead is linked to the characteristic SST pattern, and therefore OHT variability in the subpolar North Atlantic. When subpolar ocean heat transport is strong at the initial- ization of a hindcast, the skill of SST hindcasts in the northeast Atlantic 2 to 9 years into the future is significantly higher than when the ocean heat transport is weak at initialization. The asymmetric effect of strong and weak phases of subpolar OHT on SST variability that preconditions asymmetric hindcast skill is robust in non-initialized versions of the same climate model. The skill of decadal SST predictions therefore ro- bustly depends on the climate state at the start of a prediction. I show in this dissertation that hindcast skill changes over time and thus cannot be immediately translated into the credibility of a forecast. Instead, the credibility of a decadal climate forecast depends on the climate state at the start of the forecast. For North Atlantic SST forecasts, the strength of subpolar North Atlantic OHT at the start of the forecast can be used to estimate its credibility. Findings presented in this dissertation suggest that physical mechanisms might be used to improve conventional estimates of the credibility of a climate forecast on the economically and politically relevant decadal time scale.Die Möglichkeit, das Klima für einige Jahre glaubhaft vorherzusagen, erweckte zuletzt umfangreiches öffentliches und ökonomisches Interesse. Wissenschaftliche Studien quan- tifizieren die Glaubwürdigkeit solcher Vorhersagen, indem sie die durchschnittliche Vor- hersagequalität der letzten ca. 50 Jahre diagnostizieren. Solche dekadischen Vorher- sagen von Erdoberflächentemperaturen in der Nordatlantikregion zeigten besonders hohe Qualität. Der Grund für diese hohe Vorhersagequalität in der Nordatlantik- region ist bisher jedoch unbekannt. Indes beeinflussen Schwankungen im Transport von Wärme aus dem tropischen in den subpolaren Nordatlantik (ocean heat transport, OHT ) nordatlantische Wasseroberflächentemperaturen (sea surface temperatures, SSTs) für etwa zehn Jahre. In dieser Dissertation zeige ich Verbindungen von niederfrequenten Schwankungen des OHT zu der Qualität dekadischer SST-Vorhersagen auf. Weiterhin diskutiere ich, wie die Kenntnis der Stärke des OHT im subpolaren Nordatlantik zu Be- ginn einer einzelnen SST Vorhersage genutzt werden kann, um die erwartbare Qualität dieser Vorhersage abzuschätzen. Mit Hilfe initialisierter numerischer Modellsimulationen des gesamten zwanzigsten Jahr- hunderts bestätige ich frühere Studien, indem ich zeige, dass OHT-Schwankungen die Variabilität von SSTs für bis zu 3-10 Jahre beeinflussen können. Ein charakteristisches SST-Muster mit warmen Temperaturen im nordost-Atlantik und kalten Temperaturen in der Golfstromregion erscheint nach starken OHT-Phasen und anders herum. Dieses Muster entsteht aus stetig wachsenden Wärmeanomalien im oberen Ozean, welche aus OHT-Anomalien resultieren, die sich im Nordatlantik südwärts fortpflanzen. Basierend auf diesen Analysen erweitere ich bisherige Studien und analysiere starke und schwache OHT-Phasen separat. Dies offenbart einen asymmetrischen Effekt starker und schwacher OHT-Phasen: starke OHT Phasen bei 50◦N beeinflussen SSTs stärker und nachhaltiger als schwache. Ich zeige hier erstmals, dass die Qualität von SST-Vorhersagen für 3-10 Jahre in die Zukunft mit diesem charakteristischen SST-Muster, und somit mit ozeanischem Wärme- transport, zusammenhängt. Wenn OHT zu Beginn einer Vorhersage in einer starken Phase ist, ist die Vorhersagequalität von SSTs für 2-9 Jahre in die Zukunft signifikant besser, als wenn der Ozean zu Beginn der Vorhersage wenig Wärme transportiert. Diese Asymmetrie ist robust in unterschiedlichen Realisationen des selben Klimamodells. Die Qualität dekadischer SST-Vorhersagen hängt daher vom klimatischen Zustand zu Be- ginn der Vorhersage ab. Ich zeige in dieser Dissertation, dass die Qualität dekadischer Temperaturvorhersagen zeitabhängig ist, und daher Qualitätsabschätzungen für die Vergangenheit für Vorher- sagen der Zukunft nicht anwendbar sind. Tatsächlich bedingt der klimatische Zustand zu Beginn einer Vorhersage deren Qualität. Bei der dekadischen Vorhersage nordat-lantischer SSTs kann der ozeanische Wärmetransport im Nordatlantik als Kriterium zur Abschätzung der erwarteten Qualität einer Vorhersage genutzt werden. Ergebnisse, die ich in dieser Dissertation präsentiere, deuten darauf hin, dass physikalische Mech- anismen genutzt werden können, um konventionelle Abschätzungen der Qualität von Klimavorhersagen für den ökonomisch und politisch interessanten dekadischen Zeitraum zu verbessern

Assessing blood brain barrier dynamics or identifying or measuring selected substances, including ethanol or toxins, in a subject by analyzing Raman spectrum signals

A non-invasive method for analyzing the blood-brain barrier includes obtaining a Raman spectrum of a selected portion of the eye and monitoring the Raman spectrum to ascertain a change to the dynamics of the blood brain barrier.Also, non-invasive methods for determining the brain or blood level of an analyte of interest, such as glucose, drugs, alcohol, poisons, and the like, comprises: generating an excitation laser beam at a selected wavelength (e.g., at a wavelength of about 400 to 900 nanometers); focusing the excitation laser beam into the anterior chamber of an eye of the subject so that aqueous humor, vitreous humor, or one or more conjunctiva vessels in the eye is illuminated; detecting (preferably confocally detecting) a Raman spectrum from the illuminated portion of the eye; and then determining the blood level or brain level (intracranial or cerebral spinal fluid level) of an analyte of interest for the subject from the Raman spectrum. In certain embodiments, the detecting step may be followed by the step of subtracting a confounding fluorescence spectrum from the Raman spectrum to produce a difference spectrum; and determining the blood level and/or brain level of the analyte of interest for the subject from that difference spectrum, preferably using linear or nonlinear multivariate analysis such as partial least squares analysis. Apparatus for carrying out the foregoing methods are also disclosed

Non-invasive method of measuring cerebral spinal fluid pressure

The invention provides a method of non-invasively determining intracranial pressure from measurements of an eye. A parameter of an optic nerve of the eye is determined, along with an intraocular pressure of the eye. The intracranial pressure may be determined from the intraocular pressure and the parameter

Non-invasive glucose monitor

A non-invasive method for determining blood level of an analyte of interest, such as glucose, comprises: generating an excitation laser beam (e.g., at a wavelength of 700 to 900 nanometers); focusing the excitation laser beam into the anterior chamber of an eye of the subject so that aqueous humor in the anterior chamber is illuminated; detecting (preferably confocally detecting) a Raman spectrum from the illuminated aqueous humor; and then determining the blood glucose level (or the level of another analyte of interest) for the subject from the Raman spectrum. Preferably, the detecting step is followed by the step of subtracting a confounding fluorescence spectrum from the Raman spectrum to produce a difference spectrum; and determining the blood level of the analyte of interest for the subject from that difference spectrum, preferably using linear or nonlinear multivariate analysis such as partial least squares analysis. Apparatus for carrying out the foregoing method is also disclosed

T-scores in African American Women

Many older bone densitometer (DXA) machines are programmed to calculate T-scores for African- American patients using peak African-American bone mass as reference standard. This presents a problem because most data regarding fracture risk has been derived using Caucasian data (Binkley 2002). If the T-score for an African-American woman is calculated using a race-adjusted reference, the same absolute bone density will yield a lower T-score for an African- American than for a Caucasian woman. For this reason, the International Society for Clinical Densitometry has recommended that T-scores for all women, regardless of ethnicity, be calculated from Caucasian reference standards (ISCD 2007)

Self-organizing maps identify windows of opportunity for seasonal European summer predictions

We combine a machine learning method and ensemble climate predictions to investigate windows of opportunity for seasonal predictability of European summer climate associated with the North Atlantic jet stream. We particularly focus on the impact of North Atlantic spring sea surface temperatures (SST) on the four dominant atmospheric teleconnections associated with the jet stream: the summer North Atlantic Oscillation (NAO) in positive and negative phases, the Atlantic Ridge (At. Ridge), and Atlantic Low (At. Low). We go beyond standard forecast practices by not only identifying these atmospheric teleconnections and their SST precursors but by making use of these identified precursors in the analysis of a dynamical forecast ensemble. Specifically, we train the neural network-based classifier Self-Organizing Maps (SOM) with ERA-20C reanalysis and combine it with model simulations from the Max Planck Institute Earth System Model in mixed resolution (MPI-ESM-MR). We use two different sets of 30-member hindcast ensembles initialized every May, one for training and evaluation between 1902 and 2008, and one for verification between 1980–2016, respectively. Among the four summer atmospheric teleconnections analyzed here, we find that At. Ridge simulated by MPI-ESM-MR shows the best agreement with ERA-20C, thereby representing with its occurrence windows of opportunity for skillful summer predictions. Conversely, At. Low shows the lowest agreement, which might limit the model skill for early warning of warmer than average summers. In summary, we find that spring SST patterns identified with a SOM analysis can be used to guess the dominant summer atmospheric teleconnections at initialization and guide a sub-selection of potential skillful ensemble members. This holds especially true for At. Ridge and At. Low and is unclear for summer NAO. We show that predictive skill in the selected ensemble exceeds that of the full ensemble over regions in the Euro-Atlantic domain where spring SST significantly correlates with summer sea level pressure (SLP). In particular, we find a significant improvement in predictive skill for SLP, geopotential height at 500 hPa, and 2 m temperature at 3–4 months lead time over Scandinavia, which is robust among the two sets of hindcast ensembles. Copyright © 2022 Carvalho-Oliveira, Borchert, Zorita and Baehr

Organisation of Health Care During an Outbreak of Marburg Haemorrhagic Fever in the Democratic Republic of Congo, 1999.

Organising health care was one of the tasks of the International Scientific and Technical Committee during the 1998-1999 outbreak in Durba/Watsa, in the north-eastern province (Province Orientale), Democratic Republic of Congo. With the logistical support of Médecins sans Frontières (MSF), two isolation units were created: one at the Durba Reference Health Centre and the other at the Okimo Hospital in Watsa. Between May 6th, the day the isolation unit was installed and May 19th, 15 patients were admitted to the Durba Health Centre. In only four of them were the diagnosis of Marburg haemorrhagic fever (MHF) confirmed by laboratory examination. Protective equipment was distributed to health care workers and family members caring for patients. Information about MHF, modes of transmission and the use of barrier nursing techniques was provided to health care workers and sterilisation procedures were reviewed. In contrast to Ebola outbreaks, there was little panic among health care workers and the general public in Durba and all health services remained operational

The World Trade Organisation: a safety net for a post-brexit UK trade policy?

By electing to leave the European Union, the United Kingdom has chosen, among many other things, to leave the customs union and the single market that includes all member states and reassert its status as an individual member of the World Trade Organisation (WTO). In doing so it will take sole responsibility for the control and governance of its external trade policy with all other WTO members (including the EU) within the framework of WTO rules. This Briefing Paper aims to explore the nature of those WTO commitments and how they might impact the UK from the yet-to-be-set date of the UK’s exit from the EU (B(rexit)day)