The northern Antarctic Peninsula (NAP) is a highly
dynamic transitional zone between the subpolar-polar and oceanic-coastal
environments, and it is located in an area affected by intense climate
change, including intensification and spatial shifts of the westerlies as
well as atmospheric and oceanic warming. In the NAP area, the water masses
originate mainly from the Bellingshausen and Weddell seas, which create a
marked regional dichotomy thermohaline characteristic. Although the NAP area
has relatively easy access when compared to other Southern Ocean
environments, our understanding of the water masses' distribution and the
dynamical processes affecting the variability of the region is still
limited. That limitation is closely linked to the sparse data coverage, as is
commonly the case in most Southern Ocean environments. This work
provides a novel seasonal three-dimensional high-resolution hydrographic
gridded data set for the NAP (version 1), namely the NAPv1.0. Hydrographic
measurements from 1990 to 2019 comprising data collected by conductivity,
temperature, depth (CTD) casts; sensors from the Marine Mammals
Exploring the Oceans Pole to Pole (MEOP) consortium; and Argo floats have been optimally
interpolated to produce maps of in situ temperature, practical salinity, and
dissolved oxygen at
The northern Antarctic Peninsula (NAP; Kerr et al., 2018a) encompasses the Bransfield and Gerlache Straits, the northwestern Weddell Sea, the southernmost Drake Passage and the northern end of the west Antarctic Peninsula (WAP) environments (Fig. 1a). The NAP is a sensitive region to climate changes because it is located under the influence of the westerly winds, which are prone to current intensification and poleward migration (Marshall, 2003; Swart and Fyfe, 2012; Lin et al., 2018). The region also receives considerable freshwater input from the melting of glaciers from the Antarctic Peninsula (Cook et al., 2016; Rignot et al., 2019). Moreover, the NAP has been showing significant alterations in its water masses' physicochemical properties, such as warming, freshening, and acidification (Gordon et al., 2000; Meredith and King, 2005; Hellmer et al., 2011; Dotto et al., 2016; Kerr et al., 2018b; Lencina Avila et al., 2018; Ruiz Barlett et al., 2018), a decline in sea ice extension, and a shortening of sea ice cover season (Stammerjohn et al., 2008; Turner et al., 2013). Consequently, the local marine ecosystem is being impacted (Moline et al., 2004; Montes-Hugo et al., 2009; Mendes et al., 2013; Ferreira et al., 2020).
Map of the northern Antarctic Peninsula (NAP).
Water masses with different properties and origins reach the NAP and mix to form the dense water masses that sink and fill the deep basins of the Bransfield Strait (Gordon et al., 2000; Dotto et al., 2016; Huneke et al., 2016; van Caspel et al., 2018). High-Salinity Shelf Water (HSSW) and Low-Salinity Shelf Water (LSSW) from the Weddell Sea enter the NAP from the east, mainly contouring the Antarctic Peninsula (von Gyldenfeldt et al., 2002; Heywood et al., 2004; Thompson et al., 2009; Collares et al., 2018) and then sinking along the slope and at the Bransfield Strait's several canyons (van Caspel et al., 2018; Fig. 1b). A branch carrying modified HSSW flows southwestward along the continental shelf to the west of the Antarctic Peninsula and reaches as far as the Gerlache Strait (Sangrà et al., 2017; Kerr et al., 2018b). Conversely, modified Circumpolar Deep Water (mCDW) from the Bellingshausen Sea – a relatively warm, salty, nutrient-rich, and deoxygenated water mass derived from the intermediate waters of the Antarctic Circumpolar Current (ACC) and modified over the western Antarctic Peninsula continental shelf – enters the NAP mainly through the Bransfield Strait western basin (Smith et al., 1999; Ruiz Barlett et al., 2018), flowing northeastward along the South Shetland Islands slope as the Bransfield Current (Sangrà et al., 2011; Fig. 1b). The mCDW also intrudes into the Bransfield Strait from the southern Drake Passage between King George and Elephant islands (López et al., 1999; Gordon et al., 2000). Therefore, a cyclonic circulation pattern is created within the Bransfield Strait from currents of completely different origins defining a strong transitional signature for that whole area (García et al., 2002). Two main fronts are observed in this region: the Bransfield Front and the Peninsula Front (Sangrà et al., 2011; Fig. 1b). The Bransfield Front is the mid-depth front separating the warm waters flowing along with the Bransfield Current and the cold waters within the deep basins of the Bransfield Strait. The Peninsula Front separates, in shallow depths, the cold waters from Weddell influence and the Bransfield Strait waters. In the Gerlache Strait, mCDW from the Bellingshausen Sea also intrudes from the south and through the gaps near Anvers Island (Smith et al., 1999; García et al., 2002; Torres Parra et al., 2020; Fig. 1b). The mCDW interacts with the HSSW-sourced waters and a relatively colder mixture leaves the Gerlache Strait towards the western basin of the Bransfield Strait (Niiler et al., 1991; Zhou et al., 2002; Savidge and Amft, 2009). In the northwestern Weddell Sea, the Antarctic Slope Front separates the coastal from the open ocean waters circulating within the Weddell Gyre (Heywood et al., 2004). Part of the dense waters that circulate in the Powell Basin eventually leak through the Philip Passage and are exported from the Weddell Sea as Antarctic Bottom Water (Franco et al., 2007; Fig. 1b). Other routes of Antarctic Bottom Water export from the Weddell Sea are the Orkney, Bruce, and Discovery passages located to the east of South Orkney Island (Naveira Garabato et al., 2002).
For at least the past fifty years, the deep waters of the Bransfield Strait
have shown significant trends of freshening and lightening, with impacts on
the volume of these regional dense waters (Azaneu et al., 2013; Dotto et
al., 2016; Ruiz Barlett et al., 2018). Considering that these waters are
formed by a parcel of
Such a mixture of distinct water masses creates good conditions for the development of a rich biological activity in the NAP. High concentrations of phytoplankton have been documented in the Bransfield and Gerlache straits, with implications for local carbon dioxide uptake (Costa et al., 2020; Monteiro et al., 2020a, b). The high primary production also supports an abundant krill stock (Atkinson et al., 2020), which is the base of the food chain up to top predators (Seyboth et al., 2018). If the changes reported for the region continue (e.g. sea ice cover and seasonality declining, land ice melting, atmospheric and oceanic temperature warming), an imbalance or even a collapse in the regional food chain is expected (Ferreira et al., 2020). A change in the composition of phytoplankton, from diatoms to cryptophytes, has already been observed in the NAP (Mendes et al., 2013) as well as a reduction in the recruitment of juvenile krill and a general decline of krill stocks in areas of the Atlantic sector of the Southern Ocean, including the NAP (Atkinson et al., 2020).
A better understanding of the NAP oceanic and shelf circulation, as well as the connection to the Weddell and Bellingshausen seas, is important to help assess the evolution and impacts of the ocean on the ice shelves and glaciers melting downstream (Cook et al., 2016; Rignot et al., 2019). Currently, the overall change in the glaciers' area is relatively small in the Bransfield and Gerlache straits compared to the adjacent Bellingshausen Sea coastline, which is under the influence of warmer waters. However, changes in proportions of the inflowing water masses could potentially lead these regions to a Bellingshausen Sea-like scenario, where warmer oceanic conditions shape the local glacier fronts' behaviour and higher melting rates are observed (Cook et al., 2016). Ruiz Barlett et al. (2018) suggest that persistent northerly and westerly wind conditions, concurrent with La Niña and positive phases of the Southern Annular Mode (SAM), are favourable drivers for mCDW inflow into the NAP. These warm inflows are likely facilitated by the poleward displacements of the oceanic fronts associated with the ACC during La Niña events (Loeb et al., 2009). Additionally, positive SAM may restrict the connections between the Weddell Sea and the Bransfield Strait (Renner et al., 2012), with the potential of reducing the inflow of cold waters into the NAP (Dotto et al., 2016). Also, the changes in the ocean dynamics along the NAP driven by SAM and El Niño–Southern Oscillation have been recently associated with the variability of the dissolved organic carbon inventory (Avelina et al., 2020). The ongoing changes in the Southern Hemisphere wind pattern, i.e. poleward and intensification associated with positive trends in the SAM, and an increase in the energetics of the ACC (Meredith and Hogg, 2006; Hogg et al., 2015) could then lead to higher mCDW inflow into the NAP by advection (e.g. Ruiz Barlett et al., 2018) and/or eddies shed by the ACC (Martinson and McKee, 2012; Couto et al., 2017). Although the strengthening of winds tends to increase the inflow of warm waters toward the WAP continental shelf, it does not necessarily mean higher ice shelf basal melting (except for the shallower ice shelves). Conversely, models suggest a reduction of sea ice concentration associated with an enhancement of the upper ocean heat fluxes (Dinniman et al., 2012). In the NAP, mixing rate measurements are scarce, hampering the understanding of how heat fluxes in the upper and deeper ocean will respond to future wind changes in the region. In addition, there is still a lack of information regarding the water masses' fluxes and mixing between the Powell Basin in the Weddell Sea and the Bransfield Strait (Thompson et al., 2009; Azaneu et al., 2017), which would help increase our understanding of the complex coastal Antarctic system.
In this context, forecasts of the evolution of the dynamics of these regional seas and their interconnections in future climate change scenarios are needed to better understand the integrated consequences, which are being modified by the complex physical, chemical, and biological processes across the NAP environments. In general, in situ measurements in the Southern Ocean are scarce in space and time due to logistical constraints. Moreover, that scarceness impacts a proper understanding of the oceanographic processes and their interactions with the atmosphere and cryosphere, which requires robust and long-term Southern Ocean observing systems to provide high-quality measurements of the different ocean and cryosphere compartments (Meredith et al., 2013; Newman et al., 2019). Hence, high-resolution regional models are needed to integrate these data and to simulate future scenarios. In this sense, quality-controlled gridded products to feed these models are important to properly create the initial conditions in terms of the three-dimensional structure of the water masses, which are needed to capture the main oceanographic and glaciological interactions and, consequently, their future evolution.
Here, we present version 1 of a hydrographic gridded product, called NAPv1.0, comprising robust high-resolution measurements from different platforms: ship-based measurements, Argo profilers and tagged marine mammals. The gridded product covers the period from 1990 to 2019, and it has in situ temperature, salinity, and dissolved oxygen fields. NAPv1.0 can be used for several applications, including input data for ocean and climate model initialization and/or assessment and ocean reanalysis evaluation, as well as to produce and reconstruct biogeochemical properties. Finally, the NAPv1.0 represents the ocean mean state on seasonal scales for the NAP in the end 20th-century and early 21st-century.
In situ temperature, practical salinity, and dissolved oxygen (DO) data from
five main sources were used to build the database for the gridded product.
Conductivity, temperature, depth (CTD) profiles were acquired from the World
Ocean Database (
Distribution of the hydrographic data sets used to build the
NAPv1.0 climatology in
Standard depth levels (m) used to linearly interpolate the profiles and the gridded data set.
A total of 37 009 profiles of in situ temperature and 32 562 of salinity were used in this study (Fig. 3a–b). Most of these data were sampled by MEOP, followed by CTD and Argo. In autumn and winter, the amount of data collected by MEOP can be as high as 18 times compared to the other platforms. Summer and autumn were the seasons with the higher amount of data collected, followed by winter and spring. Note, however, that the high amount of data in autumn and winter is due to MEOP measurements (Fig. 3). In regards of DO, a total of 1810 profiles were used (Fig. 3c). Most of the data were sampled in summer by ship-based CTD. From this total, 701 DO profiles were acquired from GOAL in the Bransfield and Gerlache straits, eastern Bellingshausen Sea, and northwestern Weddell Sea (Kerr et al., 2018a). All years, except 2012, were covered by CTD temperature and salinity samples (Fig. S1a–b in the Supplement). Argo and MEOP data were available from 2002 and 2008, respectively, for the study region (Fig. S1 in the Supplement). DO had a better sampling covering after 2003, when the GOAL carried out studies in the region quasi-annually (Fig. S1c in the Supplement).
Most of the samples were collected in the upper ocean (up to
The different platforms have different accuracies. The initial CTD accuracy
reported for the World Ocean Database typically ranges
from
Given the higher resolution and accuracy, the CTD data were used for a
reasonableness check to verify if the gridded products can represent the
expected and accepted values of the hydrographic properties in the NAP. For
this exercise, we chose to compare only those CTD profiles closer than
The scattered hydrographic data were objectively interpolated onto a regular
grid of
The objective interpolation uses scattered observations to generate a
regular gridded and smoothed version of the original data field analysed
(Bretherton et al., 1976; Thomson and Emery, 2014). The method is based on
the Gauss–Markov theorem, which consists of an application of linear
estimation techniques for interpolating data from the multiple platforms
combined. While this improves the spatial coverage, it also smooths out the
temporal and spatial variability, resulting in a pattern that is more
representative of the large-scale mean state rather than of a specific
period. The interpolation of each grid point is affected by the neighbouring
data that fall within the smoothing lengthscales (or radius of influence)
and the relative error chosen a priori. The interpolation method also
assumes a weight to sum all observations within a specific smoothing
lengthscale. The weight is a function of the distance to the grid point and
the location of the observation only. Because the objective interpolation
fits a Gaussian function, the nearest neighbours have higher weight than the
data located closer to the edge of the radius of influence. A series of
tests were made to find the appropriate smoothing lengthscale and the a
priori relative error in order to find a balance between smoothness and
feature representativeness. The final smoothing lengthscale chosen (i.e. the radius
of influence of the interpolation) was 1
The relative error for in situ temperature calculated in the objective
interpolation at 10 m (left panels) and 1000 m (right panels) depth for
The term reasonableness check is used here to ensure that the gridded data
set meets the expected range, type, or value based on its individual
measurements. We want to examine how reasonably the NAPv1.0 can represent
the CTD profiles closer than
The NAPv1.0 shows a good agreement with the CTD profiles for the
hydrographic parameters. Approximately 62 %, 70 %, 74 %, and 65 % of
the data points fall within the difference range of
A good agreement between the NAPv1.0 and the CTD profiles is also observed
for
With regards to DO, approximately 65 %, 87 %, 87 %, and 80 % of the
data points fall within the difference range of
The NAPv1.0 represents qualitatively well the surface thermal dichotomy
regime of the NAP waters: a warm variety with Bellingshausen Sea and ACC
influence to the west and a cold Weddell Sea-sourced water to the east
(Fig. 6a). A surface thermal front that splits these two regimes near the
Antarctic Peninsula, likely depicting the Peninsula Front (López et al.,
1999; Sangrà et al., 2011), is more visible in summer (Fig. 6a–d). On the
surface, the coastal Weddell Sea-sourced waters are saltier and denser
compared to the warm waters to the west of the NAP (Figs. 6e–h and 7a–d).
Thus, the Peninsula Front seems to be baroclinic (Sangrà et al., 2011).
The DO is relatively supersaturated everywhere, with higher concentrations
found close to the James Ross Island, the Gerlache Strait, and the northern
end of the WAP (Fig. 7e–h). These regions are generally associated with high
primary productivity, which could explain the relatively higher values of DO
(Mendes et al., 2012; Detoni et al., 2015; Costa et al., 2020). Seasonally,
the NAPv1.0 represents a general decrease in
Surface maps of NAPv1.0 at 10 m depth for conservative temperature
(
Surface maps of NAPv1.0 at 10 m depth for neutral density (
In deeper layers, the dichotomy regime of the NAP is still evident,
reflecting the presence of warm and salty waters associated with the CDW to
the west of the NAP and the Warm Deep Water (WDW; a warm, salty, and
poorly oxygenated intermediate water mass presented in the Weddell Sea and
derived from the mixing between CDW and Winter Water) within the offshore
zone of the Weddell Sea and Powell Basin (Figs. S4–S7 in the Supplement). Intrusions of mCDW
are observed in the eastern Bellingshausen Sea through deep channels,
reaching the Gerlache Strait and the western basin of the Bransfield Strait
(Figs. S4a–S7a in the Supplement). After entering the Bransfield Strait, the mCDW warm signal
follows the slope of the South Shetland Islands as the narrow Bransfield
Current (Niiler et al., 1991; López et al., 1999; Zhou et al., 2006;
Sangrà et al., 2011). However, given the lengthscales chosen, this
current is not well represented in the NAPv1.0. Although the routes of mCDW
inflow are relatively well known, few studies focused on the periodicity of
these inflows into the NAP (e.g. Ruiz Barlett et al., 2018) or on the fast
response of these inflows associated with the wind forcing (e.g. McKee and
Martinson, 2020a). WDW is another water mass that composes the deep waters
of the Bransfield Strait (Gordon et al., 2000). Although the NAPv1.0
suggests the existence of an intrusion of this water mass into the eastern
basin at
In all seasons, the Bransfield Strait is colder, fresher, denser, and oxygen-richer compared to the adjacent regions in deeper basins (Figs. S4–S7 in the Supplement) and is associated with the higher contribution of HSSW (Gordon et al., 2000; Dotto et al., 2016). Moreover, the water masses in the Bransfield Strait central basin are also slightly denser than in the eastern basin (e.g. Fig. S4g in the Supplement), suggesting a different origin of these waters (Gordon et al., 2000; van Caspel et al., 2018). The NAPv1.0 represents quite well a narrow cold and oxygen saturated path along the continental slope of the Weddell Sea at 500 m depth (Fig. S4a–d in the Supplement). At the Powell Basin, these water masses follow the bathymetry and enter the Bransfield Strait, thus connecting the Weddell Sea and the NAP (Heywood et al., 2004). Although slightly less visible than in summer, the narrow thermal signal along the continental slope of the Weddell Sea is observed entering the Bransfield Strait in autumn and spring (Figs. S5a–S7a in the Supplement). In winter, likely due to limited in situ data, this signal is not totally clear (Fig. S6 in the Supplement). These dense waters that flood the central NAP deep levels seem to follow the shortcuts of the canyons that cut across the Antarctic Peninsula continental shelf in the Bransfield Strait (Figs. S4–S7 in the Supplement). The higher DO in that deep region indicates a fast route of Weddell Sea shelf waters and hence a relatively small residence time (van Caspel et al., 2015, 2018). At deeper levels, the bathymetric constraints restrict the connection of the shelf waters from the Weddell Sea, and the dense waters that sink into the Bransfield Strait retain their quasi-pure properties (Figs. S4e–S7e in the Supplement; Gordon et al., 2000; Dotto et al., 2016). The horizontal maps clearly show the importance of the Bransfield Strait in trapping the shelf waters of the Weddell Sea, making it an in situ laboratory to study temporal changes of these water masses. Given the spatial scales and the smoothing following the gridding procedure, Bransfield Strait mesoscale and submesoscale eddies (Sangrà et al., 2011) are not observed in the NAPv1.0.
To exemplify the representation of the water column of NAPv1.0, we selected
six sections crossing different parts of the NAP and adjacent regions (Fig. 1a). To the southwest of the Bransfield Strait, along the section between
Livingston Island and the Antarctic Peninsula, relatively warmer conditions
are observed from the upper ocean to the bottom layers (Fig. 8a). An
intrusion of mCDW is observed between 62.7–62.8
Summer vertical sections crossing the Bransfield Strait between
Livingston Island and the Antarctic Peninsula (
We now evaluate the NAPv1.0 in sections crosscutting the WAP at the
WOCE-SR4 West (hereafter, SR4) and along the Scotia Arc – a route of
Antarctic Bottom Water export (Fig. 1a; Franco et al., 2007). At the WAP
(Fig. 9a–d), the NAPv1.0 shows high values of
Summer vertical sections along the western Antarctic Peninsula
(WAP;
Most climatological products are built to represent the global ocean and its large-scale basins, such as the Southern Ocean. The NAP, on the other hand, is a relatively small region but highly dynamical and ecologically important to connect regional environments (Kerr et al., 2018a). In this context, we now compare the NAPv1.0 with some other available gridded products, widely used by the ocean community, to show how effective it is to have regional climatologies, especially in areas of intense spatial and temporal variability. For these comparisons, we chose to use the WOA and CARS climatologies and the SOSE state estimate previously described in Sect. 2. Although SOSE is based on a model, and one could argue that comparing it with a gridded product is not a fair comparison, we decided to used it because the data coverage of the Southern Ocean is relatively poor in space and time, and many studies have used SOSE as a benchmark to evaluate other ocean model outputs (e.g. Spence et al., 2017; Russell et al., 2018). In addition, SOSE has been used as initial conditions for simulations within the Bransfield Strait (e.g. Zhou et al., 2020). Despite the limitations of state estimate and ocean reanalysis (e.g. Mazloff et al., 2010; Azaneu et al., 2014; Dotto et al., 2014; Aguiar et al., 2017; Verdy and Mazloff, 2017), combining model and observations, such as in SOSE, leads to great improvements on the comprehension of the Southern Ocean dynamics (e.g. van Sebille et al., 2013; Abernathey et al., 2016; Rodriguez et al., 2016; Tamsitt et al., 2017).
The vertical water mass structure of the NAP and adjacent regions is well
represented by the NAPv1.0 (Fig. 10a–b). The density distribution and
thermohaline ranges agree well with the CTD casts (closer than 6 km from the grid
points), as previously shown (Sect. 4.1). The summer-averaged WOA is colder
and saltier at the surface, but the intermediate to deep ocean seems to have
thermohaline range and density structure similar to observations (Fig. 10c–d). The summer-estimated CARS seems to represent well the NAP region,
despite being a product with coarser resolution. It has the range of
Summer conservative-temperature–absolute-salinity (
Now, to present the water mass structure, we show the representation of
these products along the several sections at the NAP and adjacent regions.
We start showing the representation of the climatologies in the central area
of the NAP, i.e. the Bransfield Strait, because it has a transitional
regime between cold and warm conditions and it is highly dynamical. WOA
unveils the upper ocean considerably colder, and despite having similar
ranges of
Summer vertical sections for WOA (left panels), CARS (middle
panels), and SOSE (right panels) along the Bransfield Strait (Fig. 1a).
Regarding the other sections in the Bransfield Strait (Fig. 1a), no product
captured the Peninsula and Bransfield fronts as well as NAPv1.0, likely due
to their coarser resolution (Fig. 12a, b, f, g, k, l). The mid-depth inflow of
mCDW is better represented in CARS, where it is restricted to the South
Shetland Islands side. In WOA and SOSE, the mCDW seems to be present in the
whole meridional extent of the Bransfield Strait (Fig. 12a, b, f, g, k, l), which
creates a band of higher temperatures in levels deeper than 200 m in both
products compared to NAPv1.0 (Fig. S14 in the Supplement). As previously noticed, the
temperature range of CARS is in better agreement with our regional
climatology (Fig. S14 in the Supplement). In terms of
Summer vertical sections of conservative temperature
(
Summer vertical sections of neutral density (
In the adjacent regions of the NAP, where the oceanographic regime is less dynamical, WOA, CARS, and SOSE represent the vertical structure of the water masses relatively better than within the central NAP (Figs. 12 and 13). All of them successfully represent the core of CDW offshore, the upward tilting of the isotherms and isopycnals towards the continental slope, and the CDW accessing the WAP continental shelf (Figs. 12 and 13). In the Weddell Sea, all products represent the core of the WDW and the thermal and density distinction of Weddell Sea Deep Water and Weddell Sea Bottom Water. However, only CARS can represent the downslope flow of cold and dense waters at the continental slope, in agreement with NAPv1.0 and observations (Figs. 12 and 13). Along the Scotia Arc, despite all products roughly agreeing regarding the distribution of the warmer water parcel (Fig. 12), only CARS and SOSE represent the export of lighter Weddell Sea Deep Water through the Philip Passage (Fig. 13), in agreement with NAPv1.0 (Fig. 9k) and observations (Franco et al., 2007).
One must keep in mind that WOA and CARS are global climatologies, and their
relatively low-resolution (i.e.
In summary, the NAPv1.0 is robust in the representation of many described dynamic features of the region and, to our knowledge, its hydrographic fields closely follow the observations better than any other available product. Hence, the NAPv1.0 can be used to represent the mean state conditions as well as to feed ocean regional models of the highly transitional and dynamic NAP environments. However, a few caveats can be identified in the NAPv1.0.
In situ data are spatially and temporally sparse in the Southern Ocean. The Argo and MEOP data sets could have the potential to overcome this uneven sampling; however, a few regions are still undersampled, such as the western Weddell Sea (Fig. 2). To avoid creating larger errors (and unreal hydrographic values) in the interpolation procedure, we decided to avoid those regions by masking the final products.
CTD data are still the only data that can be used to measure deeper (
Another limitation of our climatology regards the DO field. As most of the CTD measurements were conducted in summer, the greatest representation of this field is restricted to that season. In addition, a considerable number of DO measurements were conducted by the GOAL, restricted to the Bransfield and Gerlache straits during summer (Fig. 3c). The development of biogeochemical Argo floats could increase the amount of available DO data in the future for different seasons (Roemmich et al., 2019), which would improve the representation of the different climatologies.
The grid scale (
Finally, the NAPv1.0 product brings a novel tool and opens plenty of possible future applications to better understand the regional circulation and hydrography along the NAP, a recognized marine climate hotspot (Kerr et al., 2018a). This climatology will be useful not only to observers and modellers, but also to ecologists and anyone interested in the oceanographic conditions and behaviour of the NAP region.
The seasonal NAPv1.0 (Dotto et al., 2021) is available at
We have presented a novel gridded hydrographic product for the NAP and
adjacent regions generated by optimal interpolation using hydrographic data
from CTD, Argo, and MEOP between 1990–2019. The gridded product has a spatial
resolution of
The supplement related to this article is available online at:
All authors designed and conceptualized the study. TSD led the study, data processing, and writing of the manuscript. RK, MMM, and CAEG lead the GOAL projects and contributed substantially to writing the manuscript.
The authors declare that they have no conflict of interest.
The authors thank
the officers and crew of the polar vessels
This study is part of the activities of the Brazilian High Latitude Oceanography Group (GOAL) within the Brazilian Antarctic Program (PROANTAR). GOAL has been funded by and/or has received logistical support from the Brazilian Ministry of the Environment (MMA); the Brazilian Ministry of Science, Technology, and Innovation (MCTI); the Council for Research and Scientific Development of Brazil (CNPq); the Brazilian Navy; the Inter-ministerial Secretariat for Sea Resources (SECIRM); the National Institute of Science and Technology of the Cryosphere (INCT CRIOSFERA; CNPq grant nos. 573720/2008-8 and 465680/2014-3); and the Research Support Foundation of the State of Rio Grande do Sul (FAPERGS grant No. 17/2551-000518-0). This study was conducted within the activities of the REDE-1, SOS-CLIMATE, POLARCANION,PRO-OASIS, NAUTILUS, INTERBIOTA, PROVOCCAR, and ECOPELAGOS projects (CNPq grant nos. 550370/2002-1, 520189/2006-0, 556848/2009-8, 565040/2010-3, 405869/2013-4, 407889/2013-2, 442628/2018-8 and 442637/2018-7, respectively). Financial support was also received from Coordination for the Improvement of Higher Education Personnel (CAPES) through the project CAPES “Ciências do Mar” (grant no. 23038.001421/2014-30). CAPES also provided free access to many relevant journals though the portal “Periódicos CAPES” and the activities of the Graduate Program in Oceanology. Tiago S. Dotto acknowledges financial support from CNPq PDJ scholarship grant no. 151248/2019-2. Rodrigo Kerr, Mauricio M. Mata, and Carlos A. E. Garcia are granted with researcher fellowships from CNPq grant nos. 304937/2018-5, 306896/2015-0, and 309932/2019-0, respectively.
This paper was edited by Giuseppe M. R. Manzella and reviewed by Hartmut Hellmer and one anonymous referee.