Circulation of the thermocline salinity maximum waters off the Northern Brazil as inferred from in situ measurements and numerical results

High resolution hydrographic observations of temperature and salinity are used to analyse the subsurface circulation along the coast of North Brazil, off the Amazon mouth, between 2° S and 6° N. Observations are presented from four cruises carried out in different periods of the year (March–May 1995, May–June 1999, July–August 2001 and October–November 1997). Numerical model outputs complement the results of the shipboard measurements, and are used to complete the descriptions of mesoscale circulation. The Salinity Maximum Waters are here analyzed, principally in order to describe the penetration of waters originating in the Southern Hemisphere toward the Northern Hemisphere through the North Brazil Current (NBC)/North Brazil Undercurrent (NBUC). Our results show that, if the Equatorial Undercurrent (EUC) is fed by Northern Atlantic Waters, this contribution may only occur in the ocean interior, east of the western boundary around 100 m depth. Modeling results indicate a southward penetration of the Western Boundary Undercurrent (WBUC) below the thermocline, along the North Brazilian coast into the EUC or the North Equatorial Undercurrent (NEUC) (around 48° W–3° N). The WBUC in the region does not flow more south than 3° N. The northern waters are diverted eastward either by the NBC retroflection or by the northern edge of the associated clockwise rings. The existence of subsurface mesoscale rings associated to the NBC retroflection is evidenced, without any signature in the surface layer, so confirming earlier numerical model outputs. These subsurface anticyclones, linked to the NBC/NBUC retroflection into the North Equatorial Undercurrent and the EUC, contribute to the transport of South Atlantic high salinity water into the Northern Hemisphere

Surface treatment of glass vials for lyophilization: Implications for vacuum-induced surface freezing

Freeze-drying is commonly used to increase the shelf-life of pharmaceuticals and biopharmaceuticals. Freezing represents a crucial phase in the freeze-drying process, as it determines both cycle efficiency and product quality. For this reason, different strategies have been developed to allow for a better control of freezing, among them, the so-called vacuum-induced surface freezing (VISF), which makes it possible to trigger nucleation at the same time in all the vials being processed. We studied the effect of different vial types, characterized by the presence of hydrophilic (sulfate treatment) or hydrophobic (siliconization and TopLyo Si–O–C–H layer) inner coatings, on the application of VISF. We observed that hydrophobic coatings promoted boiling and blow-up phenomena, resulting in unacceptable aesthetic defects in the final product. In contrast, hydrophilic coatings increased the risk of fogging (i.e., the undesired creeping of the product upward along the inner vial surface). We also found that the addition of a surfactant (Tween 80) to the formulation suppressed boiling in hydrophobic-coated vials, but it enhanced the formation of bubbles. This undesired bubbling events induced by the surfactant could, however, be eliminated by a degassing step prior to the application of VISF. Overall, the combination of degasification and surfactant addition seems to be a promising strategy for the successful induction of nucleation by VISF in hydrophobic vials

Evolving and sustaining ocean best practices and standards for the next decade

The oceans play a key role in global issues such as climate change, food security, and human health. Given their vast dimensions and internal complexity, efficient monitoring and predicting of the planet's ocean must be a collaborative effort of both regional and global scale. A first and foremost requirement for such collaborative ocean observing is the need to follow well-defined and reproducible methods across activities: from strategies for structuring observing systems, sensor deployment and usage, and the generation of data and information products, to ethical and governance aspects when executing ocean observing. To meet the urgent, planet-wide challenges we face, methods across all aspects of ocean observing should be broadly adopted by the ocean community and, where appropriate, should evolve into "Ocean Best Practices." While many groups have created best practices, they are scattered across the Web or buried in local repositories and many have yet to be digitized. To reduce this fragmentation, we introduce a new open access, permanent, digital repository of best practices documentation (oceanbestpractices.org) that is part of the Ocean Best Practices System (OBPS). The new OBPS provides an opportunity space for the centralized and coordinated improvement of ocean observing methods. The OBPS repository employs user-friendly software to significantly improve discovery and access to methods. The software includes advanced semantic technologies for search capabilities to enhance repository operations. In addition to the repository, the OBPS also includes a peer reviewed journal research topic, a forum for community discussion and a training activity for use of best practices. Together, these components serve to realize a core objective of the OBPS, which is to enable the ocean community to create superior methods for every activity in ocean observing from research to operations to applications that are agreed upon and broadly adopted across communities. Using selected ocean observing examples, we show how the OBPS supports this objective. This paper lays out a future vision of ocean best practices and how OBPS will contribute to improving ocean observing in the decade to come

Seasonal and regional variability of upper ocean diapycnal heat flux in the Atlantic cold tongue

SST variability within the Atlantic cold tongue (ACT) region is of climatic relevance for the surrounding continents. A multi cruise data set of microstructure observations is used to infer regional as well as seasonal variability of upper ocean mixing and diapycnal heat flux within the ACT region. The variability in mixing intensity is related to the variability in large scale background conditions, which were additionally observed during the cruises. The observations indicate fundamental differences in background conditions in terms of shear and stratification below the mixed layer (ML) for the western and eastern equatorial ACT region causing critical Froude numbers (Fr) to be more frequently observed in the western equatorial ACT. The distribution of critical Fr occurrence below the ML reflects the regional and seasonal variability of mixing intensity. Turbulent dissipation rates (ε) at the equator (2°N-2°S) are strongly increased in the upper thermocline compared to off-equatorial locations. In addition, ε is elevated in the western equatorial ACT compared to the east from May to November, whereas boreal summer appears as the season of highest mixing intensities throughout the equatorial ACT region, coinciding with ACT development. Diapycnal heat fluxes at the base of the ML in the western equatorial ACT region inferred from ε and stratification range from a maximum of 90 Wm-2 in boreal summer to 55 Wm-2 in September and 40 Wm-2 in November. In the eastern equatorial ACT region maximum values of about 25 Wm-2 were estimated during boreal summer reducing to about 5 Wm-2 towards the end of the year. Outside the equatorial region, inferred diapycnal heat fluxes are comparably low rarely exceeding 10 Wm-2. Integrating the obtained heat flux estimates in the ML heat budget at 10°W on the equator accentuates the diapycnal heat flux as the largest ML cooling term during boreal summer and early autumn. In the western equatorial ACT elevated meridional velocity shear in the upper thermocline contributes to the enhanced diapycnal heat flux within this region during boreal summer and autumn. The elevated meridional velocity shear appears to be associated with intra-seasonal wave activity

Impact of the equatorial deep jets on estimates of zonal transports in the Atlantic

The structure and variability of the zonal equatorial flow in the Atlantic is studied on the basis of velocity profiles obtained with lowered Acoustic Doppler Current Profilers during multiple surveys. The vertical extent of the zonal currents is found to vary considerably. It can be as small as 100 m or as large as 1000 m. In the Atlantic, vertical scales of 400-600 m have been associated with the equatorial deep jets (they are also frequently called deep jets or stacked jets). Typical amplitudes of the zonal velocity are about 20 cm s(-1). An analysis of quasi-synoptic surveys indicates that the zonal extent of most jets is likely to be at least 27°. They can rise or deepen from west to east, although the deepening was observed more often and is often more pronounced. The west to east deepening can be as large as 320 m/10°. Basin-wide mean depth changes of the jets are mostly on the order of 50 m/10°, and the largest depth changes are typically observed between 35° and 23° W. The existence of these changes indicates that vertically propagating, equatorially trapped, waves might be one cause for the jet structure. However, the dependence of the slope on the longitude indicates that other processes must be involved as well. The typical vertical extent of the jets is small enough to result in several direction changes of the zonal flow in the Antarctic Intermediate Water (AAIW) and the North Atlantic Deep Water (NADW) layer. From transport estimates for 14 meridional sections it is found that the transport for the westward component of the flow within the AAIW layer (500-1000 m) can be as large as -24 Sv (1 Sv = 10(6) M, s(-1)) within 1° of the equator. For the eastward component of the flow in the AAIW layer the transport can be as large as 8 Sv. Adding the transport components for each section results in a range of total AAIW transports from -24 to 7 Sv. This suggest that the annual mean transport of AAIW is westward. The only months with eastward total transports are June and July. This is consistent with earlier Lagrangian and some other observations that indicated that the AAIW flow along the equator is governed by an annual cycle. In the NADW layer (1200-3900 m) the transport for the westward (eastward) flow can be as large as -25 Sv (23 Sv) within 1° of the equator. This results in a range of total NADW transports from -10 to 18 Sv. The variations of the total transports of AAIW and NADW are anti-correlated, with a correlation coefficient of -0.86. Since only eight sections reached deep enough to allow transport estimates in the NADW layer it is more difficult to come to a conclusion about the mean transport in this layer than for the transport in the AAIW layer (for the latter layer 14 sections were available). Nevertheless, the obtained estimates suggest that the total NADW transport may be eastward. Published by Elsevier Ltd