ABSTRACT:The present study assesses the medium-range probabilistic forecast issued using an improved version of the Centre for Weather Forecasting and Climate Studies (CPTEC) Ensemble Prediction System (EPS). This version includes improvements made to the method used to select the fastest growing modes (the empirical orthogonal functions (EOF)-based method), and the bias correction. Results demonstrate that this improved CPTEC EPS surpasses the skills of the current operational version. An assessment was conducted using the framework of the THORPEX Interactive Grand Global Ensemble (TIGGE), comparing three configurations of the CPTEC EPS to the EPS from the National Centre for Environment Prediction (NCEP) and the Korean Meteorological Agency (KMA). The score adopted for metrics was the continuous ranked probability score (CRPS), calculated for absolute temperature at the 850 hPa level (T850), and sea level pressure (SLP). The best improvements were found for T850 over the Northern and Southern Hemispheres, with a general increase of 9 days in the useful forecast horizon. SLP augments are more modest, with useful performance extension of 2 days in the Northern Hemisphere and 3 days in the Southern Hemisphere. All the EPSs over the Southern Hemisphere showed a general decrease in performance when compared with their respective counterparts in the Northern Hemisphere, both for T850 and SLP. Over the Tropics, SLP is better predicted than T850 by most EPSs, but the NCEP EPS presents the best performance over this region with similar scores for the two variables.

We investigated the formation and evolution of the South Atlantic subtropical mode water using data from profiling conductivity, temperature, and depth sensors (CTD) deployed in April–May 2015 and from two customized Argo floats that drifted from April 2015 to June 2017. From the CTD data, we observed a mode water layer below the seasonal thermocline that deepened from the southern side of the area to the north. The two Argo floats remained in the proximity of the cruise area for 2 years. Their slow displacement and recirculating patterns allowed us to observe the changes in the temperature and salinity structure before and after the formation period. We observed that the potential vorticity of newly formed mode water was O[10−1 to 10−2] of the mean value found in the whole mode water layer. There is a significant correspondence between the phases of the time integral of surface heat fluxes and the sea surface temperature. Mode water is observed to form at the integrated heat flux minimum phase. The relationship between the air‐sea fluxes and sea surface temperature promotes the necessary preconditioning for the mode water formation. Once this was established, the outcropping of the mode water, that was at about 100 m depth, coincided with the passage of an atmospheric cold frontal system. This event suggests that the mode water formation can be triggered by the passage of cold fronts.

Lista de Siglas e Acrônimos vii Lista de Figuras ix Lista de Tabelas xiii 2008 apresentou aumento da energia associada aos períodos anual e bianual em relação aos valores obtidos da análise do período de 1993-2000. Essa alteração do espectro não teve relação com a alteração média da frente termal detectada porém, houve aumento significativo da variabilidade meridional da posição da frente média, possivelmente devido a um aumento do fluxo da CB. Maior variabilidade também foi observada nos mapas de velocidade geostrófica para o mesmo período de 2001-2008. Estes mapas exibiram ainda um possível posicionamento mais austral da CB, corroborando o aumento da variabilidade oriundo da maior instabilidade gerada por ondas planetárias na região da CBM.

Population growth poses one of the greatest challenges for human survival in the 21st Century and, increasingly, man is turning to the sea for food and energy. As the ocean has no physical boundaries, it is inevitable that some of these activities will affect the seashore and jurisdictional waters of coastal States, negatively affecting those nations’ territorial waters, with all the economic and social ramifications that entails. Recent studies point to most threats to maritime jurisdictions coming from undetected acts perpetrated on the high seas. Therefore, this article looks at potential threats in this domain and measures to mitigate those threats, in full compliance with the provisions of the United Nations Convention on the Law of the Sea. That fact, and the limitations imposed by international law, make it impossible for any one country to address these issues alone. Increasingly States need the support of hemispheric alliances, such as the Organization of American States, and transboundary water agreements such as the South Atlantic Peace and Cooperation Zone. Leveraging those alliances and agreements to reinforce maritime safety is the surest way to foster cooperation among developing nations, including those with coasts along the South Atlantic, and to prevent maritime threats from undermining their future.

En el siglo XXI se aceleraron los cambios en el panorama de defensa y seguridad, principalmente por la interferencia de nuevas tecnologías y la diversificación de actores que influyen en el campo de acción en múltiples dominios. Estos cambios deben ser estudiados continuamente para mantener las estructuras y alianzas de defensa y seguridad actualizadas y capaces de enfrentar todas las acciones alternativas, con una preparación que las haga estar siempre un paso adelante de la estrategia contraria. Este artículo pretende identificar, a través de un análisis prospectivo, los desafíos y amenazas que enfrenta y enfrentará la Junta Interamericana de Defensa (JID) en el complejo panorama futuro de amenazas multidimensionales, multidominio y transnacionales. Adicionalmente, el documento busca oportunidades de cooperación internacional que puedan proporcionar a la JID herramientas y nuevos procedimientos para mejorar sus capacidades, estudiando otra alianza regional y compleja como la Unión Europea, mediante un enfoque de defensa y seguridad. Las acciones propuestas no sólo reforzarán la propia JID, sino que fortalecerán a la Organización de Estados Americanos (OEA) para alcanzar un papel pionero como alianza internacional comprometida con la equidad de los pueblos y la defensa de la democracia, en un mundo real no polarizado y multilateralista.