Magnetospheric substorm effects on energetic electrons in the outer Van Allen belt /Summary of technical report CR-137/

Substorm-associated acceleration effects on electron increases in post-midnight sector of outer radiation bel

Experimental verification of drift shell splitting in the distorted magnetosphere

OGO-3 and ATS-1 data used in experimental verification of drift shell splitting in distorted magnetospher

A renormalization fixed point for Lorenz maps

A Lorenz map is a Poincar\'e map for a three-dimensional Lorenz flow. We describe the theory of renormalization for Lorenz maps with a critical point and prove that a restriction of the renormalization operator acting on such maps has a hyperbolic fixed point. The proof is computer assisted and we include a detailed exposition on how to make rigorous estimates using a computer as well as the implementation of the estimates.Comment: 29 pages, 2 figure

Coastal settlements rehabilitation affected by the 2010 tsunami in Pelluhue county, Chile

Indexación: Scopus.La Comuna de Pelluhue fue una de las más afectadas durante el terremoto y tsunami del 27 de febrero de 2010 en Chile central, registrando 47 fallecidos, el mayor número de muertes per-cápita del país. Este estudio se orienta a analizar la resiliencia de los centros urbanos de la comuna, desde sus principales instancias: preparación, resistencia, recuperación y adaptación. Los daños generados por el tsunami se estudian mediante un levantamiento in-situ, complementado con levantamientos efectuados en 2013 y 2015, consulta de percepción de seguridad y un análisis del impacto de los instrumentos de planificación territorial en la rehabilitación de los centros urbanos. De estos estudios se concluye que la comuna experimentó una rápida recuperación de infraestructura entre 2010 y 2012. Las modificaciones incorporadas en la ordenanza del Plan Regulador Comunal a finales de 2012 promovieron el uso de una nueva tipología estructural adaptada al riesgo de tsunami en la Zona Turística de Borde Costero (ZTBC-1). El uso de marcos estructurales de madera y hormigón en el primer piso, se adoptó en respuesta al bajo coeficiente de ocupación de suelo sugerido en la ordenanza del Plan Regulador Comunal para dicha zona, sin necesariamente cumplir con criterios de diseño estructural. En otras zonas ubicadas en el área inundada, no obstante, se reconstruyó sin adoptar criterios de adaptación. Aun cuando se implementó una consulta, que no tiene la representación adecuada de toda la población, el sondeo indica que el plan de emergencia implementado por ONEMI, por su parte, generó una mejor percepción de seguridad en las zonas de riesgo por parte de los residentes, pero los visitantes desconocen las medidas de evacuación vigentes.The Pelluhue country was one of the most affected during the earthquake and tsunami of February 27, 2010 in central Chile, with 47 deaths, the highest number of per-capita deaths in the country. This study is oriented to analyze the resilience of the urban centers of the commune, from its principal instances: preparation, resistance, recovery and adaptation. The damage generated by the tsunami is studied through an on-site survey, supplemented by surveys conducted in 2013 and 2015, a safety perception consultation and an analysis of the impact of territorial planning instruments in the rehabilitation of urban centers. From these studies it is concluded that the commune experienced a rapid infrastructure recovery between 2010 and 2012. The modifications incorporated in the ordinance of the Community Regulatory Plan at the end of 2012 promoted the use of a new structural typology adapted to the tsunami risk in the Coastal Tourist Zone (ZTBC-1). The use of wood and concrete structural frames on the first floor was adopted in response to the low coefficient of soil occupation suggested in the ordinance of the Community Regulatory Plan for that area, without necessarily complying with structural design criteria. However, in some other areas, within the flooded area, it was rebuilt without adopting adaptation criteria. Even when a consultation was implemented, which does not have adequate representation of the entire population, the survey indicates that the emergency plan implemented by ONEMI, in turn, generated a better perception of safety in the risk areas by residents, but visitors are unaware of the current evacuation measures. © 2017, Escuela de Ciencias del Mar. All rights reserved.http://www.lajar.cl/pdf/imar/v45n4/Art%C3%ADculo_45_4_03.pd

Present and Past Mineral Dust Variations- a Cross-Disciplinary Challenge for Research

In its recently published report, the intergovernmental Panel Climate Change identified the role of mineral dust in the Earth system and the uncertainties it introduces to the total aerosol radiative forcing and climate projections as key topics for future research. Achieving a thorough understanding of feedback associated with eolian dust is a challenge for a number of Earth science disciplines as mineral dust processes operate on a wide range of spatial and temporal scales. On the other hand, studies of mineral dust contribute significantly to research on past climatic and environment conditions enabled by dust preserved in different kinds of depositional paleoclimate archives.Such work has been the focus of PAGES' recently concluded ADOM (Atmospheric Dust during the last glacial cycle: Observations and Modeling) working, which was established in 2008 with the goal of combining reconstructions of climate and atmospheric circulation from terrestrial, marine and ice-core records with modern dust evidence and model simulations of past and present atmospheric circulation

The new SPIL logo: A face for the future

No abstract

Large deglacial shifts of the Pacific Intertropical Convergence Zone

The position of the Intertropical Convergence Zone (ITCZ) is sensitive to changes in the balance of heat between the hemispheres which has fundamental implications for tropical hydrology and atmospheric circulation. Although the ITCZ is thought to experience the largest shifts in position during deglacial stadial events, the magnitude of shifts has proven difficult to reconstruct, in part because of a paucity of high-resolution records, particularly those including spatial components. Here we track the position of the ITCZ from 150 to 110 ka at three sites in the central equatorial Pacific at sub-millennial time resolution. Our results provide evidence of large, abrupt changes in tropical climate during the penultimate deglaciation, coincident with North Atlantic Heinrich Stadial 11 (~136–129 ka). We identify this event both as a Northern Hemisphere increase in aeolian dust and as a shift in the mean position of the ITCZ a minimum of 4° southwards at 160° W

On the Hyperbolicity of Lorenz Renormalization

We consider infinitely renormalizable Lorenz maps with real critical exponent $\alpha>1$ and combinatorial type which is monotone and satisfies a long return condition. For these combinatorial types we prove the existence of periodic points of the renormalization operator, and that each map in the limit set of renormalization has an associated unstable manifold. An unstable manifold defines a family of Lorenz maps and we prove that each infinitely renormalizable combinatorial type (satisfying the above conditions) has a unique representative within such a family. We also prove that each infinitely renormalizable map has no wandering intervals and that the closure of the forward orbits of its critical values is a Cantor attractor of measure zero.Comment: 63 pages; 10 figure

Productivity patterns in the Equatorial Pacific over the last 30,000 years

The equatorial Pacific traverses a number of productivity regimes, from the highly productive coastal upwelling along Peru to the near gyre-like productivity lows along the international dateline, making it an ideal target for investigating how biogeochemical systems respond to changing oceanographic conditions over time. However, conflicting reconstructions of productivity during periods of rapid climate change, like the last deglaciation, render the spatiotemporal response of equatorial Pacific productivity ambiguous. In this study, surface productivity since the last glacial period (30,000 years ago) is reconstructed from seven cores near the Line Islands, central equatorial Pacific, and integrated with productivity records from across the equatorial Pacific. Three coherent deglacial patterns in productivity are identified: (1) a monotonic glacial-Holocene increase in productivity, primarily along the Equator, associated with increasing nutrient concentrations over time; (2) a deglacial peak in productivity ~15,000 years ago due to transient entrainment of nutrient rich southern-sourced deep waters; and (3) possible precessional cycles in productivity in the eastern equatorial Pacific that may be related to Intertropical Convergence Zone migration and potential interactions with El Niño–Southern Oscillation dynamics. These findings suggest that productivity was generally lower during the glacial period, a trend observed zonally across the equatorial Pacific, while deglacial peaks in productivity may be prominent only in the east

Variations in export production, lithogenic sediment transport and iron fertilization in the Pacific sector of the Drake Passage over the past 400 kyr

Changes in Southern Ocean export production have broad biogeochemical and climatic implications. Specifically, iron fertilization likely increased subantarctic nutrient utilization and enhanced the efficiency of the biological pump during glacials. However, past export production in the subantarctic southeastern Pacific is poorly documented, and its connection to Fe fertilization, potentially related to Patagonian Ice Sheet dynamics, is unknown. We report biological productivity changes over the past 400 kyr, based on a combination of 230Thxs-normalized and stratigraphy-based mass accumulation rates of biogenic barium, organic carbon, biogenic opal and calcium carbonate as indicators of paleo-export production in a sediment core upstream of the Drake Passage (57.5∘ S, 70.3∘ W). In addition, we use fluxes of iron and lithogenic material as proxies for terrigenous input, and thus potential micronutrient supply. Stratigraphy-based mass accumulation rates are strongly influenced by bottom-current dynamics, which result in variable sediment focussing or winnowing at our site. Carbonate is virtually absent in the core, except during peak interglacial intervals of the Holocene, and Marine Isotope Stages (MIS) 5 and 11, likely caused by transient decreases in carbonate dissolution. All other proxies suggest that export production increased during most glacial periods, coinciding with high iron fluxes. Such augmented glacial iron fluxes at the core site were most likely derived from glaciogenic input from the Patagonian Ice Sheet promoting the growth of phytoplankton. Additionally, glacial export production peaks are also consistent with northward shifts of the Subantarctic and Polar Fronts, which positioned our site south of the Subantarctic Front and closer to silicic acid-rich waters of the Polar Frontal Zone. However, glacial export production near the Drake Passage was lower than in the Atlantic and Indian sectors of the Southern Ocean, which may relate to complete consumption of silicic acid in the study area. Our results underline the importance of micro-nutrient fertilization through lateral terrigenous input from South America rather than eolian transport and exemplify the role of frontal shifts and nutrient limitation for past productivity changes in the Pacific entrance to the Drake Passage