Regional and temporal variability of sinking organic matter in the subtropical northeast Atlantic Ocean: a biomarker diagnosis

Sinking particles through the pelagic ocean have been traditionally considered the most important vehicle by which the biological pump sequesters carbon in the ocean interior. Nevertheless, regional scale variability in particle flux is a major outstanding issue in oceanography. 5 Here, we have studied the regional and temporal variability of total particulate organic matter fluxes, as well as chloropigment and total hydrolyzed amino acid (THAA) compositions and fluxes in the Canary Current region, between 20–30 N, during two contrasting periods: August 2006, characterized by warm and stratified waters, but also intense winds which enhanced eddy development south of the Canary Islands, 10 and February 2007, characterized by colder waters, less stratification and higher productivity. We found that the eddy-field generated south of the Canary Islands enhanced by >2 times particulate organic carbon (POC) export with respect to stations (FF; farfield) outside the eddy-field influence. We also observed flux increases of one order of magnitude in chloropigment and 70% in THAA in the eddy-field relative to FF stations. 15 Principal Components Analysis (PCA) was performed to assess changes in particulate organic matter composition between stations. At eddy-field stations, higher chlorophyll enrichment reflected “fresher” material, while at FF stations a higher proportion of pheophytin indicated greater degradation due to microbes and microzooplankton. PCA also suggests that phytoplankton community structure, particularly the dominance of 20 diatoms versus carbonate-rich plankton, is the major factor influencing the POC export within the eddy field. In February, POC export fluxes were the highest ever reported for this area, reaching values of 15 mmolCm−2 d−1 at 200m depth. Compositional changes in pigments and THAA indicate that the source of sinking particles varies zonally and meridionally and suggest that sinking particles were more degraded at 25 near-coastal stations relative to open ocean stations.

¿Cómo convivir con la escasez de agua? El caso de las Islas Canarias

Escasez de agua no necesariamente significa pobreza, como se dedcice de un análisis de áreas geográficas. Hay países relativamente ricos con escasos recursos hidricos y paises pobres con abundancia de agua dulce. La sociedad humana desarrollada dispone de recursos científicos, tecnicos, económicos, institucionales \; politicos para aáecuar la disponibilidad de agua a la demanda y viceversa, de un modo tendente a la sustentabilidad, siempre y cuando las actividades econornicas se modifiquen convenientemente y esa sustentabilidad sea un objetivo social deseado y participadc. El Archioiélago de Canarias esta en la región érida sahariana, aunque con ireas de pluviosidad relativamente elevada en sus vecientes septentrionales afectadas por la circulación de los vientos alisios y masas atlánticas de aire húmedo. La escasez de agua es algo bien asumido e internalizado en muchas de las áreas insulares canarias, en especial :ras la explosión demográfica del siglo XX. No por ello deja de ser una región europea ae economía aceptable y notablemente rica relativa al entorno geográfico próximo. La consecución de agua dulce es el resultado acumulado de un gran esfuerzo económico e imaginativo secular, con matices diferentes en cada isla y en cada parte de una misma isla. Sin embargo subsisten o han aparecido graves disfunciones a causa de la rapida evolución, arraigo de actividades agricolas no sustentables, debilidad insritucional y escasa participación ciudadana en la ~oliticad el agua a largo plazo, en un ambiente científico y técnico aiin por consolidar. No obstante. los logros en captaciór, de aguas subterraneas sor. espectaculares y el avance en desalinización y reutilización son m ~nyoto rios. ABSTRACT: relatively rich with scarce water resources and poor countries that have plenty of freshwater. A developed human society has scientific, technical, economic, institutional and policy resources to adapt water availability to demand, and vice versa, in a way that tends to sustainabílity. This needs modifying conveniently economic activities and making sustainability a wanted and participated social goal. The Archipelago of the Canaries is placed in the Sanaran dry belt, although there are some areas of relatively high rainfall in the north-facing slopes of the isiands, which intersect the circulation of trade winds and atlantic humid air masses. Water scarciTy is something well assumed and internalised in many of the areas of the Canaries, especially afier the demographic explosion of the XX century. But this does not imply poverty; actually it is an Eu8-opeanr egion wlth acceptable economic leve1 and notably rich respect the nearby geographical area. Freshwater wining is tne accumulated result of secular economic and imaginative efforts, which present differences from island to island and even incide the same island. Nowever some serious malfuncrions remain oí have appeared o'ue 10 the fast evolution, persistence of unsustainable agricultura1 activities 2nd still scarce public participation ir) long-term water policies. This happens in a scientific and iechnical environment which is stil! to be consolidated. However there are spectacular achievements in groundw~ter wining, and there are notorious progress in desalination and water reuse.

The impact of different surface parameterizations and vertical resolutions on the simulation of seabreeze episodes at the island of Fuerteventura

[EN] On 8-10 April 2007, several episodes of intense sea-breeze fronts were registered at the island of Fuerteventura (Canary Islands). The sea-breeze circulation was primary driven by daytime heating contrasts between land and the Atlantic Ocean during a period of weak trade winds. Numerical simulations of these events were carried out using the 3.1.1 version of the Weather Research and Forecasting (WRF) Model. Two different domains with 6.6-km and 2.2-km horizontal grid spacing and two sets with 27 and 51 vertical sigma levels were defined. The simulation was performed using two-way interactive nesting between the first and the second domain, using different land surface model parameterizations (Thermal diffusion, Noah LSM and RUC) for comparison. Initial conditions were provided by the NCAR Dataset analysis from April 2007, which were improved using surface and upper-air observations. The poster is focused on the 9 April episode.

Local flow under weak trade wind regime

[EN] On 8-10 April 2007, several episodes of intense sea-breeze fronts were registered at the islands of Fuerteventura and Lanzarote (Canary Islands). The sea-breeze circulation was primary driven by daytime heating contrasts between land and the Atlantic Ocean during a period of weak trade winds. Numerical simulations of these events were carried out using the 3.1.1 version of the Weather Research and Forecasting (WRF-ARW) Model. Three different domains with 6.6-km, 2.2-km and 0.7-km horizontal grid spacing and two sets with 51 and 70 vertical sigma levels were defined. The simulation was performed using two-way interactive nesting between the first and the second domain, using different land surface model parameterizations (Thermal diffusion, Noah LSM and RUC) for comparison. Initial conditions were provided by the NCAR Dataset analysis from April 2007, which were improved using surface and upper-air observations. The poster is focused on the 10 April episode.

Regional and temporal variability of sinking organic matter in the subtropical northeast Atlantic Ocean: A biomarker diagnosis

[EN] Sinking particles through the pelagic ocean have been traditionally considered the most important vehicle by which the biological pump sequesters carbon in the ocean interior. Nevertheless, regional scale variability in particle flux is a major outstanding issue in oceanography. Here, we have studied the regional and temporal variability of total particulate organic matter fluxes, as well as chloropigment and total hydrolyzed amino acid (THAA) compositions and fluxes in the Canary Current region, between 20?30_ N, during two contrasting periods: August 2006, characterized by warm and stratified waters, but also intense winds which enhanced eddy development south of the Canary Islands, and February 2007, characterized by colder waters, less stratification and higher productivity. We found that the eddyfield generated south of the Canary Islands enhanced by >2 times particulate organic carbon (POC) export with respect to stations (FF; far-field) outside the eddy-field influence. We also observed flux increases of one order of magnitude in chloropigment and 2 times in THAA in the eddy-field relative to FF stations. Principal Components Analysis (PCA) was performed to assess changes in particulate organic matter composition between stations. At eddy-field stations, higher chlorophyll enrichment reflected ?fresher? material, while at FF stations a higher proportion of pheophytin indicated greater degradation due to microbes and microzooplankton. PCA also suggests that phytoplankton community structure, particularly the dominance of diatoms versus carbonate-rich plankton, is the major factor influencing the POC export within the eddy field. In February, POC export POC export within the eddy field. In February, POC export fluxes were the highest ever reported for this area, reaching values of _15 mmolCm?2 d?1 at 200m depth. Compositional changes in pigments and THAA indicate that the source of sinking particles varies zonally and meridionally and suggest that sinking particles were more degraded at near-coastal stations relative to open ocean stations.

An observational study of oceanic eddy generation mechanisms by tall deep-water islands (Gran Canaria)

[EN]Oceanic eddy generation by tall deep-water islands is common phenomenon. It is recognized that these eddies may have a significant impact on the marine system and related biogeochemical fluxes. Hence, it is important to establish favourable conditions for their generation. With this objective, we present an observational study on eddy generation mechanisms by tall deep-water islands, using as a case study the island of Gran Canaria. Observations show that the main generation mechanism is topographic forcing, which leads to eddy generation when the incident oceanic flow is sufficiently intense. Wind shear at the island wake may acts only as an additional eddy-generation trigger mechanism when the impinging oceanic flow is not sufficiently intense. For the case of the island of Gran Canaria we have observed a mean of ten generated cyclonic eddies per year. Eddies are more frequently generated in summer coinciding with intense Trade winds and Canary Current.