Geothermal heating in the Panama Basin. Part II: abyssal water mass transformation

Diabatic upwelling of abyssal waters is investigated in the Panama Basin employing the water mass transformation framework of Walin [1982]. We find that, in large areas of the basin, the bottom boundary layer is very weakly stratified and extends hundreds of meters above the sea floor. Within the weakly stratified bottom boundary layer (wsBBL) neutral density layers intercept the bottom of the basin. The area of these density layer incrops increases gradually as the abyssal waters become lighter. Large incrop areas are associated with strong diabatic upwelling of abyssal water, geothermal heating being the largest buoyancy source. While a significant amount of water mass transformation is due to extreme turbulence downstream of the Ecuador Trench, the only abyssal water inflow passage, water mass transformation across the upper boundary of abyssal water layer is accomplished almost entirely by geothermal heating

Geothermal heating in the Panama Basin. Part I: hydrography of the basin

The Panama Basin serves as a laboratory to investigate abyssal water upwelling. The basin has only a single abyssal water inflow pathway through the narrow Ecuador Trench. The estimated critical inflow through the Trench reaches 0.34 ± 0.07 m s−1, resulting in an abyssal water volume inflow of 0.29 ± 0.07 Sv. The same trench carries the return flow of basin waters that starts just 200 m above the bottom and is approximately 400 m deeper than the depth of the next possible deep water exchange pathway at the Carnegie Ridge Saddle. The curvature of temperature‐salinity diagrams is used to differentiate the effect of geothermal heating on the deep Panama Basin waters that was found to reach as high as 2200 m depth, which is about 500 m above the upper boundary of the abyssal water layer

The weakly stratified bottom boundary layer of the global ocean

The weakly stratified bottom boundary layer (wsBBL) of the global ocean is currently unmapped; even the definition of the wsBBL layer is yet lacking. However, recent studies point to the wsBBL as a region where most of the abyssal water transformation takes place. In this study, historical high‐resolution density profiles are used to map the properties of the wsBBL in the global ocean. We use a density gradient criteria ( urn:x-wiley:21699275:media:jgrc22951:jgrc22951-math-0001 kg m– 4) to define the top of the layer. The thickness of the wsBBL varies from several meters to over a thousand meters and can be used as a rule of thumb to differentiate basin walls from the basin bottom, respectively. Although the thickness varies greatly, the pressure at the top of the wsBBL varies relatively smoothly allowing us to map its distribution across the ocean along with the density of the wsBBL. The neutral density, γwsBBL, and pressure, PwsBBL, of the upper boundary of the wsBBL are highly correlated within each ocean basin. Diagrams of γwsBBL versus PwsBBL clearly differentiate the different basins, connected by the narrow channels, along the pathways of abyssal water circulation. The diagrams give insight into the different mechanisms of abyssal water transformation and highlight locations where transformation happens: inter‐basin channels and over some parts of mid‐oceanic ridges such as found in the Brazil Basin, in the Guiana Basin, and in the Southwest Pacific Basin

Estudio de la Capa Límite Atmosférica Nocturna: SABLES2006

[EN]Preliminary results from SABLES2006 field campaign (Stable Atmospheric Boundary Layer Experiment in Spain) are shown. This campaign took place from 19 June to 5 July 2006 at the CIBA (Research Centre for the Lower Atmosphere) site, which is located at Valladolid on a fairly homogeneous terrain. Different instrumentation was available on a 100m tower (cups and sonic anemometers, thermometers, humidity sensors and three high resolution microbarometers). Additionally, a triangular array of microbarometers close to surface was also deployed in order to characterize wave events. Moreover a tethered balloon was used to get vertical profiles of the atmosphere up to 1000 m. Mean micrometeorological variables, stability and turbulent parameters (all of them 5 minute averaged) have been analysed for 10 consecutive nights, showing the main characteristics of the stable nocturnal boundary layer: surface-based inversions, intermittent turbulence, katabatic winds, low level jets, developing gravity waves, etc. The boundary layer height in stable conditions is also evaluated from different definitions. The range of values found is analysed.[ES]En este trabajo se muestran resultados preliminares de la campaña SABLES2006 (Experimento en Capa Límite Atmosférica Estable en España). La campaña tuvo lugar entre el 19 de junio y el 5 de julio en el CIBA (Centro de Investigaciones en la Baja Atmósfera), localizando en la provincia de Valladolid sobre terreno homogéneo. En una torre de 100 m se dispuso de diferente instrumentación (anemómetros de cazoletas y sónicos, termómetros, sensores de humedad y tres microbarómetros de alta sensibilidad). Adicionalmente, se utilizaron tres microbarómetros dispuestos en un triángulo junto a la superficie con el objeto de caracterizar eventos ondulatorios. Además de empleó un globo cautivo para obtener perfiles de la atmósfera hasta 1000 m. Se han analizado variables micrometeorológicas medias, parámetros de estabilidad y turbulentos (todos promediados en 5 minutos) para 10 noches consecutivas, mostrando las principales características de la capa límite estable nocturna: inversiones junto al suelo, turbulencia intermitente, vientos catabáticos, chorros a bajo nivel, desarrollo de ondas de gravedad, etc. La altura de la capa límite en condiciones de estabilidad fue evaluada según diferentes definiciones. Los rangos de valores encontrados han sido analizados.This work has been funded by the Spanish Ministry of Education & Science from the projects: CGL2004-03109 and CGL2006-12474-C03-03. IV PRICIT program (supported by Comunidad de Madrid and UCM) has also partially financed this work through the Research Group “Micrometeorology and Climate Variability” (nº 910437)

Mean sea-level variability along the northeast American Atlantic coast and the roles of the wind and the overturning circulation

The variability in mean sea level (MSL) during 1950–2009 along the northeast American Atlantic coast north of Cape Hatteras has been studied, using data from tide gauges and satellite altimetry and information from the Liverpool/Hadley Centre (LHC) ocean model, thereby providing new insights into the spatial and temporal scales of the variability. Although a relationship between sea level and the overturning circulation can be identified (an increase of approximately 1.5 cm in MSL for a decrease of 1 Sv in overturning transport), it is the effect of the nearshore wind forcing on the shelf that is found to dominate the interannual sea-level variability. In particular, winds are found to be capable of producing low-frequency changes in MSL (“accelerations”) in a narrow coastal band, comparable to those observed by the tide gauges. Evidence is presented supporting the idea of a “'common mode” of spatially coherent low-frequency MSL variability, both to the north and south of Cape Hatteras and throughout the northwest Atlantic, which is associated with large spatial-scale density changes from year to year

Princeps Resurgens: investigación arqueológica y documentación fotogramétrica en el estudio de una estatua romana thoracata de Los Bañales (Uncastillo, Zaragoza)

En estas líneas presentamos un conjunto de fragmentos escultóricos en mármol de Carrara recuperados en contexto secundario en el foro de la ciudad romana de Los Bañales (Uncastillo, Zaragoza) y cómo la recuperación digital de las piezas mediante el uso de la fotogrametría han permitido la reintegración digital de los fragmentos hasta recuperar el aspecto original de la escultura recuperada hasta la fecha permitiendo la documentación de los restos, un estudio científico más profundo y la divulgación de los trabajos desarrollados.In these lines we present a set of sculptural fragments in Carrara marble recovered in a secondary context in the forum of the Roman city of Los Bañales (Uncastillo, Zaragoza) and how digital recovery of these set using photogrammetric procedures has allowed the reintegration of digital fragments to restore the original appearance of the sculpture recovered so far, allowing the documentation of the remains, a deeper scientific study and the dissemination of the performed works

Local and regional characterisation of the diurnal mountain wind systems in the Guadarrama mountain range (Spain)

Póster presentado en: EGU General Assembly celebrada del 23 al 28 de abril de 2017 en Viena, Austria.This research has been partially funded by the Spanish Government (MINECO projects CGL2015-65627-C3-3-R and CGL2012-37416-C04-02) and by the GR3/14 program (supported by UCM and Banco Santander) through the Research Group “Micrometeorology and Climate Variability” (No.910437)

Observations of a diapycnal shortcut to adiabatic upwelling of Antarctic Circumpolar Deep Water

In the Southern Ocean, small-scale turbulence causes diapycnal mixing which influences important water mass transformations, in turn impacting large-scale ocean transports such as the Meridional Overturning Circulation (MOC), a key controller of Earth'sclimate. We present direct observations of mixing over the Antarctic continental slope between water masses that are part of the Southern Ocean MOC. A 12-hour time-series of microstructure turbulence measurements, hydrography and velocity observations off Elephant Island, north of the Antarctic Peninsula, reveals two concurrent bursts of elevated dissipation of O(10–6Wkg–1, resulting in heat fluxes ~10 times higher than basin-integrated Drake Passage estimates. This occurs across the boundary between adjacent adiabatic upwelling and downwelling overturning cells. Ray tracing and topography show mixing between 300-400 m consistent with the breaking of locally-generated internal tidal waves. Since similar conditions extend to much of the Antarctic continental slope where these water masses outcrop, their transformation may contribute significantly to upwelling