Climatological distribution of dissolved inorganic nutrients in the western Mediterranean Sea (1981–2017)

The Western MEDiterranean Sea BioGeochemical Climatology (BGC-WMED, https://doi.org/10.1594/PANGAEA.930447) (Belgacem et al., 2021) presented here is a product derived from quality-controlled in situ observations. Annual mean gridded nutrient fields for the period 1981–2017 and its sub-periods 1981–2004 and 2005–2017 on a horizontal 1/4∘ × 1/4∘ grid have been produced. The biogeochemical climatology is built on 19 depth levels and for the dissolved inorganic nutrients nitrate, phosphate and orthosilicate. To generate smooth and homogeneous interpolated fields, the method of the variational inverse model (VIM) was applied. A sensitivity analysis was carried out to assess the comparability of the data product with the observational data. The BGC-WMED was then compared to other available data products, i.e., the MedBFM biogeochemical reanalysis of the Mediterranean Sea and the World Ocean Atlas 2018 (WOA18) (its biogeochemical part). The new product reproduces common features with more detailed patterns and agrees with previous records. This suggests a good reference for the region and for the scientific community for the understanding of inorganic nutrient variability in the western Mediterranean Sea, in space and in time, but our new climatology can also be used to validate numerical simulations, making it a reference data product.

Are Past Sea-Ice Reconstructions Based on Planktonic Foraminifera Realistic? Study of the Last 50 ka as a Test to Validate Reconstructed Paleohydrography Derived from Transfer Functions Applied to Their Fossil Assemblages

Since its existence, paleoceanography has relied on fossilized populations of planktonic foraminifera. Except for some extreme environments, this calcareous protist group composes most of the silty-to-sandy fraction of the marine sediments, i.e., the foraminiferal oozes, and its extraction is probably the simplest among the currently existing set of marine fossil proxies. This tool has provided significant insights in the building of knowledge on past climates based on marine archives, especially with the quantification of past hydrographical variables, which have been a turning point for major comprehensive studies and a step towards the essential junction of modelling and paleodata . In this article, using the modern analog technique and a database compiling modern analogs (n = 1007), we test the reliability of this proxy in reconstructing paleohydrographical data other than the classical sea-surface temperatures, taking advantage of an update regarding a set of extractions from the World Ocean Atlas for transfer functions. Our study focuses on the last glacial period and its high climatic variability, using a set of cores distributed along the European margin, from temperate to subpolar sites. We discuss the significance of the reconstructed parameters regarding abrupt and extreme climate events, such as the well-known Heinrich events. We tested the robustness of the newly obtained paleodata by comparing them with older published reconstructions, especially those based on the complementary dinoflagellate cyst proxy. This study shows that the potential of planktonic foraminifera permits going further in reconstructions, with a good degree of confidence; however, this implies considering ecological forcings in a more holistic perspective, with the corollary to integrate the message of this fossil protist group, i.e., the obtained parameters, in light of a cohort of other data. This article constitutes a first step in this direction.

Tekanan Bawah Laut (Pressure) Untuk Web Database Fusi Oseanografi

Permasalahan kondisi laut sangatlah dinamis. Namun dinamika ini umumnya memiliki pola bulanan dan tahunan. Sehingga tugas akhir ini akan menghitung dan menampilkan karakteristik bulanan dan tahunan dari variabel Pressure. Data eksperimen yang digunakan bersumber dari World Ocean Atlas (WOA) 2013 parameter temperature, salinity dan kedalaman, yang kemudian digunakan untuk komputasi perhitungan menghasilkan variabel Pressure. Data WOA 2013 adalah data klimatologis dari 1955- 2012 (57 tahun), dengan asumsi mewakili kondisi laut normal tanpa dipengaruhi oleh ENSO dan IOD. Namun sangat dipengaruhi dengan waktu dan kedalaman dari perairan tertentu. Diharapkan penelitian ini dapat memberikan solusi untuk Pushidrosal akan keterbatasan tentang data oseanografi dengan variabel Pressure yang disajikan dalam Purwarupa Fusi Oseanografi untuk mendukung keperluan sektor maritim maupun sektor hankam.

Seasonal mode-1 M2 internal tides from satellite altimetry

The seasonal variability of mode-1 M2 internal tides is investigated using 25 years of multi-satellite altimeter data from 1992–2017. Four seasonal internal tide models are constructed using seasonally-subsetted altimeter data and World Ocean Atlas seasonal climatologies. This work is made possible by a newly-developed mapping procedure that can significantly suppress model errors. Seasonal-mean and seasonally-variable internal tide models are derived from the four seasonal models. All the models are inter-compared and evaluated using independent CryoSat-2 data. The seasonal-mean model is overall the best model because averaging the four seasonal models further reduces model errors. The seasonally-variable models are better in the tropical zone, where large seasonal signals may overcome model errors. Each seasonal model works best in its own season and worst in its opposite season. These internal tide models reveal that mode-1 M2 internal tides are subject to significant seasonal variability and their seasonal variations are a function of location. Large seasonal variations dominantly occur in the tropical zone, where the World Ocean Atlas climatology shows strong seasonal variations in ocean stratification. Seasonal phase variations are obtained from the directionally-decomposed internal tide components. They are dominantly ±60° at the equator and up to ±120° in the central Arabian Sea. Incoherence caused by seasonal phase variations is usually <10%, but may be up to 40–50% in the tropical zone.

Validation of Sea-Surface Temperature Data for Potential OTEC Deployment in the Mexican Pacific

As the operation of an ocean thermal energy conversion (OTEC) plant depends on the temperature gradient between the surface and deeper water (SST), a variation in SST can significantly modify the energy produced. The aim of this paper is to present a comparative analysis of three sea-surface temperature databases (World Ocean Atlas (WOA), Satellite Oceanic Monitoring System (SATMO), and in situ sensor measurements). Simple linear regression and graphic comparisons allow correlations to be made between the distribution patterns of the SST data. The results show that there is no statistically significant difference between the three databases. To determine general regions where OTEC implementation is possible, at the macroscale, the WOA database is recommended, as a smaller amount of data must be analyzed. For meso- and microscales, such as specific areas of the Mexican exclusive economic zone. It is better to use SATMO and in situ measurements as a higher spatial resolution is required.

Interpreting the observed variability of deep waters in the Irminger Sea

&lt;p&gt;&lt;strong&gt;Temperature and salinity seasonal to interannual variability of Iceland Scotland Overflow Water (ISOW) and Denmark Strait Overflow Water (DSOW) is investigated by combining two in-situ datasets in the Irminger Sea for the period 1997-2020: 12-yr of repeated hydrography (1997-2018) provided by the FOUREX, OVIDE and RREX sections and 4-yr of data (2016-2020) from 8 Deep Argo floats deployed in the region between 2016 and 2018. &lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;In order to enable a consistent analysis of ocean temperature and salinity variability from unevenly distributed vertical profiles (both in space and time), it is necessary to estimate the appropriate regional climatology to be removed from every observation. Two independent procedures are followed to compute anomalies and quantify uncertainties related to the choice of climatology: First, the global 1&amp;#176;-resolution World Ocean Atlas 2018 (2005-2017 averages) climatology is retrieved from every observed profile (Deep Argo, hydrography). Second, &lt;/strong&gt;&lt;span&gt;&lt;strong&gt;the well-known and sampled OVIDE transect (2002-2018 average) is used to build a reference section of geographical anomalies that are subsequently propagated along potential vorticity contours &lt;/strong&gt;&lt;/span&gt;&lt;span&gt;&lt;strong&gt;in the Irminger Sea.&lt;/strong&gt;&lt;/span&gt;&lt;strong&gt; Neutral density surfaces 28.02 kgm&lt;/strong&gt;&lt;sup&gt;&lt;strong&gt;-3 &lt;/strong&gt;&lt;/sup&gt;&lt;strong&gt;and 28.12 kgm&lt;/strong&gt;&lt;sup&gt;&lt;strong&gt;-3&lt;/strong&gt;&lt;/sup&gt;&lt;strong&gt; are then chosen from mean OVIDE 2002-2018 gridded fields as representative of ISOW and DSOW levels, respectively. Significant decadal trends in water mass properties are revealed by repeated hydrography, whereas some striking boundary-interior spatial patterns are captured by Deep Argo floats. Property changes of ISOW and DSOW are discussed in terms of changes of source waters in the Nordic Seas, entrainment of Atlantic waters into the overflow waters and cascading events from the Greenland slope.&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Springtime Upwelling and Its Formation Mechanism in Coastal Waters of Manaung Island, Myanmar

Multisource satellite remote sensing data and the World Ocean Atlas 2018 (WOA18) temperature and salinity dataset have been used to analyze the spatial distribution, variability and possible forcing mechanisms of the upwelling off Manaung Island, Myanmar. Signals of upwelling exist off the coasts of Manaung Island, in western Myanmar during spring. It appears in February, reaches its peak in March and decays in May. Low-temperature (<28.3 °C) and high-salinity (>31.8 psu) water at the surface of this upwelling zone is caused by the upwelling of seawater from a depth below 100 m. The impact of the upwelling on temperature is more significant in the subsurface layer than that in the surface layer. In contrast, the impact of the upwelling on salinity in the surface layer is more significant. Further research reveals that the remote forcing from the equator predominantly induces the evolution of the upwelling, while the local wind forcing also contributes to strengthen the intensity of the upwelling during spring.

Baroclinic Modes over Rough Bathymetry and the Surface Deformation Radius

The deformation radius is widely used as an indication of the eddy length scale at different latitudes. The radius is usually calculated assuming a flat ocean bottom. However, bathymetry alters the baroclinic modes and hence their deformation radii. In a linear quasigeostrophic two-layer model with realistic parameters, the deep flow for a 100-km wave approaches zero with a bottom ridge roughly 10 m high, leaving a baroclinic mode that is mostly surface trapped. This is in line with published current meter studies showing a primary EOF that is surface intensified and has nearly zero flow at the bottom. The deformation radius associated with this “surface mode” is significantly larger than that of the flat bottom baroclinic mode. Using World Ocean Atlas data, the surface radius is found to be 20%–50% larger over much of the globe, and 100% larger in some regions. This in turn alters the long Rossby wave speed, which is shown to be 1.5–2 times faster than over a flat bottom. In addition, the larger deformation radius is easier to resolve in ocean models.

Karakteristik Massa Air di Perairan Barat Daya Pulau Sumba, Provinsi Nusa Tenggara Timur

Karakteristik massa air dan percampurannya dapat dipengaruhi oleh angin dan aliran air laut ke lokasi tersebut. Massa air laut terbentuk dari komposisi suhu, salinitas, dan densitas pada kedalaman tertentu. Kajian massa air pada perairan barat daya P. Sumba dilakukan menggunakan data hasil reanalysis (karakteristik massa air) seluruh lautan dunia (World Ocean Atlas 2013). Pengolahan data dilakukan berupa sebaran menegak dan melintang suhu dan salinitas, serta menentukan karakteristik massa air. Kisaran suhu perairan P. Sumba musim timur tergolong rendah, SPL berkisar 26.4 - 26.49 oC dan secara umum dari permukaan hingga dasar dengan rentang suhu 26.49 - 3.4 oC. Lapisan termoklin terjadi pada kedalaman 59.67 - 259.38 m dengan kisaran suhu 25.13 - 12.2 oC. Kisaran salinitas permukaan laut dari pantai menuju laut lepas sebesar 34.0498 - 34.1117 psu, dan nilai salinitas secara menegak adalah 34.0498 - 34.7 psu, salinitas maksimum terjadi pada perairan laut lepas, terjadi pada kedalaman dekat termoklin. Pergerakan massa air permukaan pada musim timur diperkirakan akibat angin muson tenggara. Karakteristik massa air yang terdapat ada perairan P. Sumba diperkirakan adalah North Pacific Subtropical Water yang terjadi dekat lapisan termoklin, dengan salinitas 34.55 - 34.7 psu, suhu 12 - 15°C, dan densitas 25.5 - 26. Pada lapisan dalam juga diduga terdapat massa air Indonesian Intermediate Water (IIW), dengan salinitas 34.6 - 34.7 psu, suhu 3 - 7 oC, dan densitas 27 - 27.7.