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The land-sea breeze influences the oceanography of the southern Benguela upwelling system at multiple time-scales.
No full textThe physical and biogeochemical functioning of eastern boundary upwelling systems is generally understood within the context of the upwelling - relaxation cycle, driven by sub-diurnal wind variability (i.e. with a time-scale of greater than a day). Here, we employ a realistically configured and validated 3D model of the southern Benguela upwelling system to quantify the impact of super-diurnal winds associated with the land-sea breeze (LSB). The ocean response to the LSB is found to be particularly enhanced within St Helena Bay (SHB), a hotspot for productivity which is also prone to Harmful Algal Bloom (HAB) development. We attribute the enhanced response to a combination of near-critical latitude for diurnal-inertial resonance (~32.5°S), the local enhancement of the LSB, and the local development of a shallow stratified surface layer through bay retention. Pronounced advection of the surface layer by diurnal-inertial oscillations contributes to large differences in day- and night-time sea surface temperatures (SST’s) (more than 2°C on average in SHB). Event-scale diapycnal mixing is particularly enhanced within SHB, as highlighted by a numerical experiment initialised with a subsurface passive tracer. These super-diurnal processes are shown to influence sub-diurnal dynamics within SHB through their modulation of the vertical water column structure. A deeper thermocline retains the upwelling front closer to land during active upwelling, while geostrophically-driven alongshore flow is impacted through the modulation of cross-shore pressure gradients. The results suggest that the LSB is likely to play an important role in the productivity and therefore HAB development within SHB, and highlight potential challenges for observational systems and models aiming to improve our understanding of the physical and biological functioning of the system.Challenge 4, 9PublishedReferee
Применение метода пропорциональной навигации при решении задач судовождения
No full textThe development of methods and algorithms for ship control when maneuvering relative to a moving object and the creation of automated control systems based on these developments is an urgent task of navigation. The most optimal way to implement control of a moving object relative to another moving object is based on using the proportional navigation method. As applied to navigation problems, this method has been studied at the level of describing the kinematics of the movement of two points. The mathematical model provides for a preliminary calculation of the extrapolated ship coordinates. The construction of ship motion trajectories for any given proportionality factor is carried out taking into account the dynamics of the ship and makes it possible to obtain the law of rudder shift, as well as to predict changes in the process of maneuvering such ship parameters as angular velocity and drift angle. The proposed mathematical model can be used for algorithmic and software support for automated ship control systems when maneuvering relative to a moving object.Разработка методов и алгоритмов управления судном при маневрировании относительно подвижного объекта и создание на основе этих разработок автоматизированных систем управления являются актуальными задачами судовождения. Наиболее оптимальный способ реализации управления подвижным объектом относительно другого подвижного объекта основан на применении метода пропорциональной навигации. Применительно к задачам судовождения этот метод изучен на уровне описания кинематики движения двух точек. Математическая модель предусматривает предварительный расчет экстраполируемых координат судна. Построение траекторий движения судна при любом заданном коэффициенте пропорциональности производится с учетом динамики судна и позволяет получить закон перекладки руля, а также спрогнозировать изменение в процессе маневрирования таких параметров судна, как угловая скорость и угол дрейфа. Предложенная математическая модель может быть использована для алгоритмического и программного обеспечения автоматизированных систем управления судном при маневрировании относительно подвижного объекта.PublishedReferee
Impact de l’évolution spatio-temporelle du littoral de Ghar El Melah sur l’activité de pêche lagunaire.
No full textCette étude consiste en une caractérisation sédimentologique et diachronique du système lagunaire côtier afin d’évaluer l’impact naturel et anthropique sur l’activité de pêche lagunaire. La méthodologie s’appuie sur une approche multicritère soit une analyse sédimentologique de la lagune de Ghar El Melah, complétée par une analyse morphoscopique et une étude diachronique temporelle à long et moyen terme (1881-2021) de la ligne de rivage de la lagune, et ce par l’outil statistique DSAS (Digital Shoreline Analysis System). Selon les résultats obtenus, L’étude sédimentologique du rivage de la lagune de Ghar El Melah révèle un faciès sédimentaire homogène avec des sables moyens à fins, bien classés et unimodaux. Cette étude sédimentologique confirme la dualité d’origine et du transport des apports sédimentaires. L’étude diachronique effectuée (1881-2021) révèle que le taux d'érosion maximum dans la zone d'étude est de -14,88 ±0,20 m/an au niveau de l’ancien delta de la Medjerda, le taux d'accrétion est de +7,35 ±0,20 m/an au niveau de la nouvelle embouchure de Boughaz et que la surface de la lagune a augmenté de 400,9 ha. Ce qui a impacté négativement, en synergie avec l’ensablement et l’élargissement de la passe de Boughaz, l’activité de pêche dans la lagune de Ghar El Melah. L’enquête socioéconomique a permis de mettre en exergue la situation actuelle de la pêche lagunaire et les problèmes éventuellement rencontrés. 88% des enquêtés ont décelé des changements morpho dynamiques au niveau de cette lagune, ce qui a impacté la biodiversité ichtyque et d’où l’exercice de la pêche lagunaireThis study consists of a sedimentological and diachronic characterization of the coastal lagoon system in order to assess the natural and anthropogenic impact on the lagoon fishing activity. The methodology is based on a multi-criteria approach: a sedimentological analysis of the lagoon sediments, supplemented by a morphoscopic analysis and a long and medium-term diachronic temporal study (1881-2021) of the shoreline of the lagoon of Ghar El Melah using the statistical tool DSAS (Digital Shoreline Analysis System). According to the results obtained, the sedimentological study of the shore of the lagoon of Ghar El Melah reveals homogeneous sedimentary facies with medium to fine sands, well sorted and unimodal. This sedimentological study confirms the duality of origin and transport of sedimentary inputs The diachronic study carried out reveals that the maximum erosion rate in the study area is -14.88 ± 0.20 m/year at the level of the old Medjerda delta, the accretion rate is +7.35 ± 0.20 m/year at the new mouth of Boughaz and the surface of this lagoon reveals an increase between 1881-2021 of 400.9 ha. Which negatively impacted, in synergy with the silting up and the widening of the Boughaz pass, the lagoon fishing activity. The socioeconomic survey highlights the current situation of lagoon fishing and the problems encountered. 88% of fishermen detected morphodynamic changes in this lagoon, which impacted halieutic biodiversity and hence the lagoon fishing activitiesMaster
Влияние летних атмосферных процессов в Крыму на апвеллинговые явления в районе Феодосийской и Двуякорной бухт
No full textUpwelling areas are characterized by high biological productivity, which influences both the performance of sprat fishing and the development of coastal aquaculture. Based on the satellite images of the sea surface, the time ranges for weak and strong upwelling activity in the area of Feodosia Gulf and Dvuyakornaya (Two-Anchors) Bay have been identified for June–September of 2001–2021. It has been found out that the upwelling phenomena were the most frequent in June and July in the presence of relatively warmed-up surface and cold subsurface water layers. Mildly pronounced upwellings most often developed in August, when the water warmed to considerable depth, and relatively warm waters, not drastically differing in temperature from the surface ones, entered the surface layer. Strong upwellings occurred mostly in September, when the temperature difference between the center and the surrounding waters reached 9.5 °С. Weak upwellings, where the temperature of surface waters within did not drop lower than 15.5 °С, were recorded in almost all years; strong ones, with the temperature decrease down to 12 °С, were observed in 2003–2007 and 2011–2021 in various months except for August. To a large extent, the strength of upwellings depended upon the gusts of wind during their activity period, and not on the wind velocity itself, which, during the investigated period, was predominantly lower than the average long-term one, in line with its negative trend in the recent two decades. The prevailing wind direction, both during an upwelling phenomenon and three days prior, is western. Three characteristic year ranges of the interannual variability of the atmospheric and related upwelling processes have been identified. It is shown that upwelling phenomena depend on the intensity of zonal atmospheric transfer with a significant correlation coefficient.Зоны апвеллинга характеризуются высокой биологической продуктивностью, что отражается как на успешности промысла шпрота, так и на развитии прибрежных зон аквакультуры. На основе спутниковых снимков поверхности моря в районе Феодосийской и Двуякорной бухт определены периоды слабовыраженных и интенсивных апвеллингов в июне–сентябре 2001–2021 гг. Выявлено, что наиболее часто апвеллинговые явления возникали в июне и июле при относительно прогретом поверхностном и холодном подповерхностном слоях. Слабовыраженные апвеллинги чаще всего формировались в августе при значительной глубине прогретых вод и выходе к поверхности относительно теплых неконтрастных с поверхностными вод, а интенсивные апвеллинги — в сентябре, когда разность температур центра и окружающих вод достигала 9,5 °С. Слабые апвеллинги, когда температура поверхностных вод в них не опускалась ниже 15,5 °С, отмечались практически во все годы; интенсивные, с понижением температур до 12 °С, в 2003–2007 и 2011–2021 гг. при отсутствии таковых в августе. Степень развитости апвеллингов в значительной мере определялась порывами ветра в период их действия, а не самой скоростью ветра, которая в наблюдаемый период была в основном ниже среднемноголетней в соответствии с ее отрицательным трендом последних двух десятилетий. Преобладающее направление ветра как в период апвеллинга, так и за три дня до него — западных румбов. Выделено три характерных диапазона лет межгодовой изменчивости атмосферных и связанных с ними апвеллинговых процессов. Показано, что апвеллинговые явления со значимым коэффициентом корреляции зависят от интенсивности зонального атмосферного переноса.PublishedReferee
Оценка качества поверхностных вод озера Большой и Малый Вилюй в 2021-2022 гг.
No full textThe study of the hydrochemical regime of a water body is a prerequisite for its monitoring. Hydrochemical indicators indicate water quality and dynamics of intrabasin processes. Among the main hydrochemical characteristics are: oxygen regime, the concentration of biogenic elements and organic substances in water.Изучение гидрохимического режима водоема является обязательным условием при мониторинге водных объектов. Гидрохимические показатели указывают на качество воды и динамику внутриводоемных процессов. В числе основных гидрохимических характеристик: кислородный режим, содержание биогенных элементов и органических веществ в воде.PublishedNon Referee
Informe Anual del Centro Colombiano de Datos Oceanográficos (Cecoldo) 2021
No full textDesde 2016 el Centro Colombiano de Datos Oceanográficos (Cecoldo) emite un informe anual para dar a conocer las actividades desarrolladas año tras año, los datos oceanográficos y de meteorología marina recuperados y catalogados; el establecimiento de compromisos de entrega periódica de datos; las contribuciones de datos abiertos a diferentes iniciativas académicas y científicas; la participación y aportes realizados en diferentes escenarios nacionales y regionales, y el compromiso con la difusión de la información y productos oceanográficos del país. El presente informe corresponde al séptimo número. En su primer capítulo describe campañas oceanográficas y expediciones científicas ejecutadas durante 2021, cuyos datos oceanográficos llegarán a hacer parte del Cecoldo. También se incluye una lista detallada de los datos entregados este mismo año por parte de los centros de investigaciones oceanográficas e hidrográficas y la Red de Medición de Parámetros Oceanográficos y de Meteorología Marina (RedMpomm) de la Dirección General Marítima (Dimar), para un total de 31 conjuntos de datos depositados y disponibles. En temas de gestión de datos, describe las actividades realizadas por parte del Cecoldo en su nuevo rol como responsable nacional del envío de datos para el indicador 14.3.1 de los objetivos de desarrollo sostenible (ODS), con un total de cinco conjuntos de datos enviados al portal del Programa para el Intercambio Internacional de Datos e Información Oceanográfica (IODE) de la Comisión Oceanográfica Intergubernamental (COI). En cifras, el Cecoldo nuevamente reporta un balance positivo en términos de acceso a datos e información; aunque la cantidad de solicitudes de acceso a datos no aumentó con relación al 2020, sí se observó un incremento del 20 % en el volumen de datos entregados y del 45 % en la cantidad de descargas de publicaciones técnicas y científicas disponibles en el Repositorio Digital Marítimo, Fluvial y Costero. Asimismo, se contribuyó con datos abiertos a 32 proyectos o iniciativas académicas y científicas de ciudadanos colombianos y extranjeros. Dando continuidad a las actividades interinstitucionales coordinadas desde el Cecoldo por conducto del Comité Técnico Nacional de Datos e Información Oceánicos (CTN Diocean), en 2021 se diseñó y editó la nueva publicación digital Boletín CTN Diocean, mediante la cual anualmente se darán a conocer las cifras de acceso a datos oceánicos proporcionadas por los sistemas de información nacionales, así como los aportes del país al resultado ‘Un océano accesible’ del Decenio de las Ciencias Oceánicas para el Desarrollo Sostenible 2021-2030, experiencias en buenas prácticas de gestión de datos y actividades de difusión y capacitación desarrolladas.Since 2016, the Colombian Oceanographic Data Center (Cecoldo) has issued an annual report on the activities carried out each year. This report is the seventh issue. This describes the oceanographic initiatives and scientific expeditions carried out during 2021, whose oceanographic data will become part of the NODC. It also includes the data sets delivered this year by different initiatives, for a total of 31 data sets deposited and available. In data management, it describes the submission of five data sets to the IODE portal for sustainable development goals (SDGs) 14.3.1 indicator. In metrics, an increase of 20% was observed in the volume of data delivered and 45% in the number of downloads of technical and scientific publications, contributing with open data to 32 academic and scientific projects or initiatives of Colombians and foreigners. It also continued to develop national and regional coordination activities, as well as dissemination and training of the NODC.PublishedNot Know
Snappers (Lutjanidae) reproductive aggregation sites in Zaimiuri Hernández-González1 1 the National Park San Felipe Keys, Cuba
No full textLas pesquerías basadas en las agregaciones reproductivas pueden amenazar a especies como los pargos que tienen conductas gregarias durante el período reproductivo. Esta nota ofrece elementos que sugieren la existencia de sitios de agregación no registrados previamente y no protegidos en el Parque Nacional Cayos de San Felipe (PNCSF), región suroccidental de Cuba. La información tradicional obtenida de pescadores locales y trabajadores del parque se corroboró con muestreos cualitativos y cuantitativos de peces de arrecifes y datos de pesquerías locales del 2014. En la época de reproducción de pargos (mayo a julio) se observaron grupos de entre 40-100 ejemplares de Lutjanus cyanopterus, Lutjanus synagris y Lutjanus jocu en los arrecifes de la zona occidental del PNCSF (camellones entre 15-30 m de profundidad cerca del borde de la plataforma). Dentro de esa área, se señalan dos sitios que parecen ser utilizados para agregaciones de predesove, por lo que requieren protección y ser estudiados. Los censos cuantitativos confirmaron que en mayo y junio la zona occidental tiene densidad alta de pargos adultos. También, el pico de captura de estas especies ocurrió en la época reproductiva. Se comprobó que las pesquerías se realizaron durante las migraciones de peces hacia el borde de la plataforma en áreas de la zona occidental del PNCSF, y que más del 60% de los individuos tuvieron gónadas maduras (antes de desovar). Esta información debe incentivar el estudio de las agregaciones de desove en esta región de Cuba, la protección de especies amenazadas y áreas de alta significación ecológica y la implementación de pesquerías sostenibles.Fisheries based on reproductive aggregations can threaten species such as snappers that have gregarious behavior during the reproductive period. This note provides evidence to support the existence of aggregation sites, not previously registered and unprotected, in the National Park San Felipe Keys (NPSFK), southwestern region of Cuba. Traditionalinformation obtained from local fishermen and from the park staff was complemented with qualitative and quantitative fish reef censuses and local fisheries data in 2014. In the reproductive season of snappers (May to July) groups of between 40-100 specimens of Lutjanus cyanopterus, Lutja- nus synagris and Lutjanus jocu were observed in the western area of the NPSFK on the reefs (spoor and grove between 20-30 m deep close to the platform edge). Within that area two sites are indicated that can be used for prespawning aggregation, so they require protection and study. Quanti- tative censuses confirmed that in May and June the western zone has high density of adult snappers. Also, the peak of capture of these snapper species occurred in the reproduc- tive season. It was found that fisheries carried out during fish migrations to the edge of the shelf in areas of the western area of the NPSFK and more than 60% of the individuals had mature gonads (before spawning). This information should promote the study of spawning aggregations in this region of Cuba, the protection of threatened species and areas of high ecological significance and the implementation of sustainable fisheries.PublishedReferee
The impact of damming in an Amazonian River on the synchrony of phytoplankton functional groups.
No full textThe degree at which populations are correlated in space is called spatial synchrony and can be affected by interspecific interactions, dispersion, and large-scale environmental factors, i. e. Moran effect. The study of this phenomenon can help understanding the temporal stability of communities and the underlying mechanisms. The influence of damming in a river from the Amazon basin (Santo Antônio do Jari HPP) on the synchrony of the environment and the phytoplankton community was evaluated, both for the total density and for different Reynolds functional groups. Was investigated whether the effects would be similar for the main channel (Jari River), tributaries, and for the total area (Jari + tributaries). The mean synchrony values and the confidence intervals of each abiotic variable, functional group, and the total density were estimated for the total area, Jari River and tributaries. Matrix-based multiple regression were also performed to identify the most important drivers of synchrony of the phytoplankton. Changes in the synchrony patterns were verified after the damming. The temporal dynamics of environmental variables, total density and of some functional groups was more synchronous when considering only the Jari River, than the total area or only tributaries. Environmental synchrony and environmental distance were the main mechanisms behind synchrony for some functional groups.O grau de correlação de populações no espaço é denominado sincronia espacial e pode ser afetado por interações interespecíficas, dispersão e fatores ambientais de ampla escala, (i. e., efeito Moran). O estudo deste fenômeno pode colaborar na compreensão da estabilidade temporal das comunidades e a descobrir quais os mecanismos associados ao processo. Avaliou-se a influência de um barramento em um rio da bacia Amazônica (UHE Santo Antônio do Jari) sobre a sincronia espacial ambiental e do fitoplâncton do rio Jari e tributários. Mensurou-se a sincronia (total, média e intervalo de confiança) para cada variável abiótica, para a densidade de toda a comunidade e para cada grupo funcional de Reynolds, considerando a área total (11 locais - rio Jari + tributários), apenas rio Jari (cinco locais) e apenas tributários (seis locais), utilizando uma série temporal de oito anos. Regressões matriciais múltiplas foram utilizadas para identificar os fatores determinantes da sincronia do fitoplâncton. Verificou-se mudanças nos padrões de sincronia após o barramento. A dinâmica temporal das variáveis ambientais, da densidade de toda a comunidade e de alguns grupos funcionais apresentou-se mais sincrônica quando considerado somente o rio Jari, do que toda a área ou somente os tributários. Em geral, a distância ambiental mostrou-se o preditor mais importante para explicar a sincronia espacial do que a distância geográfica.Master