Forced versus coupled dynamics in Earth system modelling and prediction

International audienceWe compare coupled nonlinear climate models and their simplified forced counterparts with respect to predictability and phase space topology. Various types of uncertainty plague climate change simulation, which is, in turn, a crucial element of Earth System modelling. Since the currently preferred strategy for simulating the climate system, or the Earth System at large, is the coupling of sub-system modules (representing, e.g. atmosphere, oceans, global vegetation), this paper explicitly addresses the errors and indeterminacies generated by the coupling procedure. The focus is on a comparison of forced dynamics as opposed to fully, i.e. intrinsically, coupled dynamics. The former represents a particular type of simulation, where the time behaviour of one complex systems component is prescribed by data or some other external information source. Such a simplifying technique is often employed in Earth System models in order to save computing resources, in particular when massive model inter-comparisons need to be carried out. Our contribution to the debate is based on the investigation of two representative model examples, namely (i) a low-dimensional coupled atmosphere-ocean simulator, and (ii) a replica-like simulator embracing corresponding components.Whereas in general the forced version (ii) is able to mimic its fully coupled counterpart (i), we show in this paper that for a considerable fraction of parameter- and state-space, the two approaches qualitatively differ. Here we take up a phenomenon concerning the predictability of coupled versus forced models that was reported earlier in this journal: the observation that the time series of the forced version display artificial predictive skill. We present an explanation in terms of nonlinear dynamical theory. In particular we observe an intermittent version of artificial predictive skill, which we call on-off synchronization, and trace it back to the appearance of unstable periodic orbits. We also find it to be governed by a scaling law that allows us to estimate the probability of artificial predictive skill. In addition to artificial predictability we observe artificial bistability for the forced version, which has not been reported so far. The results suggest that bistability and intermittent predictability, when found in a forced model set-up, should always be cross-validated with alternative coupling designs before being taken for granted

Improving Moringa Growth by Using Autochthonous and Allochthonous Arbuscular Mycorrhizal Fungi in Lake Victoria Basin

Biological methods such as mycorrhiza biotechnology used for raising and sustaining soil fertility in agricultural ecosystems close to freshwater biomes are gaining attention. However, ubiquitous ecological conditions may subject mycorrhizal management to choices that depend on inoculum sources (autochthonous or cultured). Effects of AMF on growth of M. stenopetala and M. oleifera were evaluated using three native soil types, representative of Lake Victoria basin and a standard substrate. Autochthonous AMF was harnessed from the native soils while allochthonous AMF cocktail was acquired from culture banks of Glomus hoi, G. mosseae and G. intraradices, using Plantago major as plant indicator and trap-culture. The soils were blocked according to tillage intensities. P. major supplied Moringa with AMF inoculum. To facilitate mycorrhization, nitrogen fixing bacteria (NFB) in chickpea rhizobia inoculum was integrated. The hyphopodium assays revealed > 90% arbuscle occupancy in root cortex of plants established in paddy LT soils. AMF inoculation improved growth and biomass of both Moringa species. Autochthonous AMF inoculum had relatively higher biomass turnover compared to cultured AMF. The presence of dark septate endophytes (DSE) in plant biodiversity gave a new insight into target plant performance at plant competition for nutrients. Results reveal that inoculum AMF and NFB are potential candidates in optimizing plant production technology applicable in eco-sensitive-oriented low in-put agriculture

Forced versus coupled dynamics in Earth system modelling and prediction

We compare coupled nonlinear climate models and their simplified forced counterparts with respect to predictability and phase space topology. Various types of uncertainty plague climate change simulation, which is, in turn, a crucial element of Earth System modelling. Since the currently preferred strategy for simulating the climate system, or the Earth System at large, is the coupling of sub-system modules (representing, e.g. atmosphere, oceans, global vegetation), this paper explicitly addresses the errors and indeterminacies generated by the coupling procedure. The focus is on a comparison of forced dynamics as opposed to fully, i.e. intrinsically, coupled dynamics. The former represents a particular type of simulation, where the time behaviour of one complex systems component is prescribed by data or some other external information source. Such a simplifying technique is often employed in Earth System models in order to save computing resources, in particular when massive model inter-comparisons need to be carried out. Our contribution to the debate is based on the investigation of two representative model examples, namely (i) a low-dimensional coupled atmosphere-ocean simulator, and (ii) a replica-like simulator embracing corresponding components. Whereas in general the forced version (ii) is able to mimic its fully coupled counterpart (i), we show in this paper that for a considerable fraction of parameter- and state-space, the two approaches qualitatively differ. Here we take up a phenomenon concerning the predictability of coupled versus forced models that was reported earlier in this journal: the observation that the time series of the forced version display artificial predictive skill. We present an explanation in terms of nonlinear dynamical theory. In particular we observe an intermittent version of artificial predictive skill, which we call on-off synchronization, and trace it back to the appearance of unstable periodic orbits. We also find it to be governed by a scaling law that allows us to estimate the probability of artificial predictive skill. In addition to artificial predictability we observe artificial bistability for the forced version, which has not been reported so far. The results suggest that bistability and intermittent predictability, when found in a forced model set-up, should always be cross-validated with alternative coupling designs before being taken for granted

Stability of complex hyperbolic space under curvature-normalized Ricci flow

Using the maximal regularity theory for quasilinear parabolic systems, we prove two stability results of complex hyperbolic space under the curvature-normalized Ricci flow in complex dimensions two and higher. The first result is on a closed manifold. The second result is on a complete noncompact manifold. To prove both results, we fully analyze the structure of the Lichnerowicz Laplacian on complex hyperbolic space. To prove the second result, we also define suitably weighted little H\"{o}lder spaces on a complete noncompact manifold and establish their interpolation properties.Comment: Some typos in version 2 are correcte

Regional-scale brine migration along vertical pathways due to CO2 injection - Part 1: The participatory modeling approach

Saltwater intrusion into potential drinking water aquifers due to the injection of CO₂ into deep saline aquifers is one of the potential hazards associated with the geological storage of CO₂. Thus, in a site selection process, models for predicting the fate of the displaced brine are required, for example, for a risk assessment or the optimization of pressure management concepts. From the very beginning, this research on brine migration aimed at involving expert and stakeholder knowledge and assessment in simulating the impacts of injecting CO₂ into deep saline aquifers by means of a participatory modeling process. The involvement exercise made use of two approaches. First, guideline-based interviews were carried out, aiming at eliciting expert and stakeholder knowledge and assessments of geological structures and mechanisms affecting CO₂-induced brine migration. Second, a stakeholder workshop including the World Café format yielded evaluations and judgments of the numerical modeling approach, scenario selection, and preliminary simulation results. The participatory modeling approach gained several results covering brine migration in general, the geological model sketch, scenario development, and the review of the preliminary simulation results. These results were included in revised versions of both the geological model and the numerical model, helping to improve the analysis of regional-scale brine migration along vertical pathways due to CO₂ injection

The NASA Tournament Laboratory (NTL): Improving Data Access at PDS while Spreading Joy and Engaging Students through 16 Micro-Contests

NASA PDS hosts terabytes of valuable data from hundreds of data sources and spans decades of research. Data is stored on flat-file systems regulated through careful meta dictionaries. PDS's data is available to the public through its website which supports data searches through drill-down navigation. While the system returns data quickly, result sets in response to identical input differ depending on the drill-down path a user follows. To correct this Issue, to allow custom searching, and to improve general accessibility, PDS sought to create a new data structure and API, and to use them to build applications that are a joy to use and showcase the value of the data to students, teachers and citizens. PDS engaged TopCoder and Harvard Business School through the NTL to pursue these objectives in a pilot effort. Scope was limited to Small Bodies Node data. NTL analyzed data, proposed a solution, and implemented it through a series of micro-contests. Contest focused on different segments of the problem; conceptualization, architectural design, implementation, testing, etc. To demonstrate the utility of the completed solution, NTL developed web-based and mobile applications that can compare targets, regardless of mission. To further explore the potential of the solution NTL hosted "Mash-up" challenges that integrated the API with other publically available assets, to produce consumer and teaching applications, including an Augmented Reality iPad tool. Two contests were also posted to middle and high school students via the NoNameSite.com platform, and as a result of these contests, PDS/SBN has initiated a Facebook program. These contests defined and implemented a data warehouse with the necessary migration tools to transform legacy data, produced a public web interface for the new search, developed a public API, and produced four mobile applications that we expect to appeal to users both within and, without the academic community

Bovine virus diarrhea and the vector-borne diseases Anaplasmosis and Bluetongue: a sero-surveillance in free-ranging red deer (Cervus elaphus) in selected areas of Switzerland

Due to climate changes, diseases emerging from southerly adjacent areas (Mediterranean countries) are likely to spread northward. Expanded migration of red deer harbors the risk of introducing new pathogens into a naive population of either wild or domestic animals. Little is known about the importance of red deer as a potential reservoir for diseases of domestic ruminants in Switzerland. Deer is susceptible for all three agents that were selected in this study: bovine virus diarrhea virus (BVDV), Anaplasma marginale (AM), and Bluetongue virus (BTV). The goal of this project was to establish the serological status of red deer in Switzerland concerning BVDV, AM, and BTV, and to assess the possible impact of disease dynamics with a focus on potential transmission of these diseases from red deer to cattle or vice versa. Sampling areas were selected according the following criteria: abundance of red deer, potential insect vector distribution due to climatic conditions, and traditional alpine pasture husbandry along with known migration routes of red deer. Blood samples were collected during the regular hunting season 2004 and 2005 by hunters and gamekeepers. There was no serological evidence for the presence of the vector-borne diseases AM and BT in red deer in Switzerland. Four out of 234 sera showed a positive result for BVD, corresponding to a sero-prevalence of 1.7% (95% CI 0.46–4.38). Facing the fact of the high sero-prevalence for BVD in Swiss cattle (60–80%) disease transmission from red deer to cattle in these areas under investigation is rather unlikely

Forced versus coupled dynamics in Earth system modelling and prediction

We compare coupled nonlinear climate models and their simplified forced counterparts with respect to predictability and phase space topology. Various types of uncertainty plague climate change simulation, which is, in turn, a crucial element of Earth System modelling. Since the currently preferred strategy for simulating the climate system, or the Earth System at large, is the coupling of sub-system modules (representing, e.g. atmosphere, oceans, global vegetation), this paper explicitly addresses the errors and indeterminacies generated by the coupling procedure. The focus is on a comparison of forced dynamics as opposed to fully, i.e. intrinsically, coupled dynamics. The former represents a particular type of simulation, where the time behaviour of one complex systems component is prescribed by data or some other external information source. Such a simplifying technique is often employed in Earth System models in order to save computing resources, in particular when massive model inter-comparisons need to be carried out. Our contribution to the debate is based on the investigation of two representative model examples, namely (i) a low-dimensional coupled atmosphere-ocean simulator, and (ii) a replica-like simulator embracing corresponding components.Whereas in general the forced version (ii) is able to mimic its fully coupled counterpart (i), we show in this paper that for a considerable fraction of parameter- and state-space, the two approaches qualitatively differ. Here we take up a phenomenon concerning the predictability of coupled versus forced models that was reported earlier in this journal: the observation that the time series of the forced version display artificial predictive skill. We present an explanation in terms of nonlinear dynamical theory. In particular we observe an intermittent version of artificial predictive skill, which we call on-off synchronization, and trace it back to the appearance of unstable periodic orbits. We also find it to be governed by a scaling law that allows us to estimate the probability of artificial predictive skill. In addition to artificial predictability we observe artificial bistability for the forced version, which has not been reported so far. The results suggest that bistability and intermittent predictability, when found in a forced model set-up, should always be cross-validated with alternative coupling designs before being taken for granted

Ev\u27rything\u27s Been Done Before

Photograph of William Powel in a box to the left and a photograph of Jean Harlow as she appeared in the film, Reckless is in the center.https://scholarsjunction.msstate.edu/cht-sheet-music/2844/thumbnail.jp