The upper ocean heat content in the equatorial Pacific usually serves as a primary precursor for an upcoming El Niño, while strong atmospheric perturbations such as westerly wind burst and easterly wind surge sometimes play a decisive role in determining the final intensity of the event. The tropical Pacific Ocean has just experienced a rare 3-year La Niña, which accumulated a huge amount of warm water in the western basin by the winter of 2022 with an intensity much stronger than those preceding the onset of strong El Niños in history. Using a state-of-the-art climate prediction system, here, we show that the restored warm water is sufficient for boosting a strong El Niño toward the end of 2023 and that an even stronger event could take place if a few sizable westerly wind bursts would occur in spring and early summer. This prediction is not sensitive to initial errors within the tropical Pacific but may be subject to some uncertainties brought about by influences from elsewhere. 

A strong 2023/24 El Niño is staged by tropical Pacific Ocean heat content buildup

Cloud Computing is an emerging paradigm in Information Technologies (IT). One of its major assets is the provisioning of resources based on pay-as-you-go model. Cloud resources are situated in a highly dynamic environment. However, each provisioned resource comes with functional properties and may not offer non functional properties like monitoring, reconfiguration, security, accountability, etc. In such dynamic environment, non functional properties have a critical importance to maintain the service level of resources and to make them respect the contracts between providers and consumers. In our work, we are interested in monitoring, reconfiguration and autonomic management of Cloud resources. Particularly, we put the focus on Service-based applications. Afterwards, we push further our work to treat Cloud resources. Consequently, this thesis contains two major contributions. On the first hand, we extend Service Component Architecture (SCA) in order to add monitoring and reconfiguration requirements description to components. In this context, we propose a list of transformations that dynamically adds monitoring and reconfiguration facilities to components even if they were designed without them. That alleviates the task of the developer and lets him focus just on the business of his components. To be in line with scalability of Cloud environments, we use a micro-container based approach for the deployment of components. On the second hand, we extend Open Cloud Computing Interface standards to dynamically add monitoring and reconfiguration facilities to Cloud resources while remaining agnostic to their level. This extension entails the definition of new Resources, Links and Mixins to dynamically add monitoring and reconfiguration facilities to resources. We extend the two contributions to couple monitoring and reconfiguration in order to add self management capabilities to SCA-based applications and Cloud resource. The solutions that we propose are generic, granular and are based on the de facto standards (i.e., SCA and OCCI). In this thesis manuscript, we give implementation details as well as experiments that we realized to evaluate our proposals

https://tel.archives-ouvertes.fr/tel-01123740/document

Generic Monitoring and Reconfiguration: For service-based Applications in the Cloud

Software systems are becoming more and more complex due to the integration of large scale distributed entities and the continuous evolution of these new infrastructures. All these systems are progressively integrated in our daily environment and their increasing importance have raised a dependability issue. While Service oriented architecture is providing a good level of abstraction to deal with the complexity and heterogeneity of these new infrastructures, current approaches are limited in their ability to monitor and ensure the system dependability. In this paper, we propose a framework for the autonomic management of service oriented application based on a dependability objective. Our framework proposes a novel approach which leverages peer to peer evaluation of service providers to assess the system dependability. Based on this evaluation, we propose various strategies to dynamically adapt the system to maintain the dependability level of the system to the desired objective.

https://hal.inria.fr/hal-00714357/document

Dependability-driven runtime management of service oriented architectures

In previous works we have proved that component reconfiguration in the presence of conflicts among components is non-primitive recursive, while it becomes poly-time if there are no conflicts and under the assumption that there are no components in the initial configuration. The case with non-empty initial configurations was left as an open problem, that we close in this paper by showing that, if there are legacy components that cannot be generated from scratch, the problem turns out to be PSpace-complete.

/pdf/on-the-complexity-of-reconfiguration-in-systems-with-legacy-3kdv80vmbr.pdf

On the Complexity of Reconfiguration in Systems with Legacy Components

Rapid intensification (RI) of tropical cyclones (TCs) provides a great challenge in operational forecasting and contributes significantly to the development of major TCs. RI is commonly defined as an increase in the maximum sustained surface wind speed of at least a certain threshold within 24 hr. The most widely used threshold is 30 kt (15.4 m/s), which was determined statistically. Here we propose a new definition for RI by objectively clustering TCs using the intensification rate, initial intensity, and radius of the maximum wind speed (RMW). A group of 770 samples is separated at a threshold of 45 kt (23.2 m/s). The threshold is 40 kt (20.6 m/s) for the western North Atlantic, where TC size measurements are more reliable. Monte Carlo experiments demonstrate that the proposed threshold is robust even considering the uncertainty in RMW of as high as 30 km. We show that, when a TC undergoes RI, its maximum wind speed is approximately 60 ± 15 kt (30.9 ± 7.7 m/s) and the RMW is 45 ± 20 km. The new threshold outperforms the conventional threshold of 30 kt/24 hr in describing the bimodal distribution of lifetime maximum intensity and explaining the annual count of Category 5 TCs. This new definition provides a more physically based threshold and describes a more reliable representation of extreme events. Although more comparisons are needed for operational application, it is likely to be desirable for case‐based process studies and could provide a more valuable metric for TC intensification classification and research.

Revisiting the Definition of Rapid Intensification of Tropical Cyclones by Clustering the Initial Intensity and Inner‐Core Size

Abstract Rapid intensification (RI) is an essential process in the development of strong tropical cyclones and a major challenge in prediction. RI in offshore regions is more threatening to coastal populations and economies. Although much effort has been devoted to studying basin-wide temporal-spatial fluctuations, variations of global RI events in offshore regions remain uncertain. Here, we show that compared with open oceans, where the annual RI counts do not show significant changes, offshore areas within 400 km of the coastline have experienced a significant increase in RI events, with the count tripling from 1980 to 2020. Furthermore, thermodynamic environments present more favorable conditions for this trend, and climate models show that global ocean warming has enhanced such changes. This work yields an important finding that an increasing threat of RI in coastal regions has occurred in the preceding decades, which may continue under a future warming climate. 

Recent increases in tropical cyclone rapid intensification events in global offshore regions

A new nudging scheme for the current operational climate prediction system of the National Marine Environmental Forecasting Center of China

Based on the characteristic of cloud computing, We have operated a research on the dynamic reconfiguration technique of cloud computing virtual services aiming at the management and maintenance of virtual services. The paper plots out three level dynamic reconfigure granularity about virtual services; according to different reconfiguration occasions puts forward dynamic reconfigure policies respectively in allusion to failure, system updating and user request; and designs a concrete scenario.

Research on dynamic reconfiguration technology of cloud computing virtual services

The concept of rapid growth (RG) of tropical cyclones (TCs) in the north Atlantic basin was recently proposed. RG can represent a dangerous change in TC structure because it can rapidly ramp up the TC destructive potential. However, the nature of RG behaviour remains obscure over the western north Pacific (WNP), where nearly one third of global TCs occur. In this study, TC RG in the WNP is investigated using TC best-tracks and reanalysis of data. We first define TC RG in the WNP as an increase of at least 84 km in the radius of a gale-force wind within 24 h, corresponding to the 90th percentile of all over-water changes. Monte Carlo experiments demonstrate the robustness of the threshold. Similar to that occurring in the north Atlantic, RG in the WNP is associated with the highest level of destructive potential. In addition, RG over the WNP occurs closer to the coast than for TCs in the Atlantic and more RG events in the WNP are accompanied by rapid intensification, which may significantly increase their destructive potential in a worst case scenario. Composite analysis shows that certain dynamic processes, such as radial inflow, may play an important role in the occurrence of RG. This study suggests that, apart from rapid intensification, TC RG is another important factor to consider for TC-related risk assessment in the WNP.

/pdf/rapid-growth-of-tropical-cyclone-outer-size-over-the-western-27ygorsl.pdf

Rapid Growth of Tropical Cyclone Outer Size over the Western North Pacific

Sharp Increase in rapid intensification of Arabian Sea tropical cyclones over the past decade

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