World Ocean Atlas Research Articles

A multiparametric method of interpolation using WOA05 applied to anthropogenic CO<sub>2</sub> in the Atlantic

SUMMARY: This paper describes the development of a multiparametric interpolation method and its application to anthropogenic carbon (CANT) in the Atlantic, calculated by two estimation methods using the CARINA database. The multiparametric interpolation proposed uses potential temperature (θ), salinity, conservative ‘NO’ and ‘PO’ as conservative parameters for the gridding, and the World Ocean Atlas (WOA05) as a reference for the grid structure and the indicated parameters. We thus complement CARINA data with WOA05 database in an attempt to obtain better gridded values by keeping the physical-biogeochemical sea structures. The algorithms developed here also have the prerequisite of being simple and easy to implement. To test the improvements achieved, a comparison between the proposed multiparametric method and a pure spatial interpolation for an independent parameter (O2) was made. As an application case study, CANT estimations by two methods (jC T o and TrOCA) were performed on the CARINA database and then gridded by both interpolation methods (spatial and multiparametric). Finally, a calculation of CANT inventories for the whole Atlantic Ocean was performed with the gridded values and using ETOPO2v2 as the sea bottom. Thus, the inventories were between 55.1 and 55.2 Pg-C with the jCTo method and between 57.9 and 57.6 Pg-C with the TrOCA method.

3D oceanographic data compression using 3D-ODETLAP

This paper describes a 3D environmental data compression technique for oceanographic datasets. With proper point selection, our method approximates uncompressed marine data using an over-determined system of linear equations based on, but essentially different from, the Laplacian partial differential equation. Then this approximation is refined via an error metric. These two steps work alternatively until a predefined satisfying approximation is found. Using several different datasets and metrics, we demonstrate that our method has an excellent compression ratio. To further evaluate our method, we compare it with 3D-SPIHT. 3D-ODETLAP averages 20% better compression than 3D-SPIHT on our eight test datasets, from World Ocean Atlas 2005. Our method provides up to approximately six times better compression on datasets with relatively small variance. Meanwhile, with the same approximate mean error, we demonstrate a significantly smaller maximum error compared to 3D-SPIHT and provide a feature to keep the maximum error under a user-defined limit.

Numerical simulations of spreading of the Persian Gulf outflow into the Oman Sea

Abstract. A three dimensional numerical model namely POM (Princeton Ocean Model) and observational data are used to study the Persian Gulf outflow structure and its spreading pathways during 1992. In the model, the monthly wind speed data were taken from ICOADS (International Comprehensive Ocean-Atmosphere Data Set) and the monthly SST (sea surface temperatures) were taken from AVHRR (Advanced Very High Resolution Radiometer) with the addition of monthly net shortwave radiations from NCEP (National Center for Environmental Prediction). The mean monthly precipitation rates from NCEP data and the calculated evaporation rates are used to impose the surface salinity fluxes. At the open boundaries the temperature and salinity were prescribed from the mean monthly climatological values from WOA05 (World Ocean Atlas 2005). Also the four major components of the tide were prescribed at the open boundaries. The results show that the outflow mainly originates from two branches at different depths in the Persian Gulf. The permanent branch exists during the whole year deeper than 40 m along the Gulf axis and originates from the inner parts of the Persian Gulf. The other seasonal branch forms in the vicinity of the shallow southern coasts due to high evaporation rates during winter. Near the Strait of Hormuz the two branches join and form the main outflow source water. The results of simulations reveal that during the winter the outflow boundary current mainly detaches from the coast well before Ras Al Hamra Cape, however during summer the outflow seems to follow the coast even after this Cape. This is due to a higher density of the colder outflow that leads to more sinking near the coast in winter. Thus, the outflow moves to a deeper depth of about 500 m (for which some explanations are given) while the main part detaches and spreads at a depth of about 300 m. However in summer it all moves at a depth of about 200–250 m. During winter, the deeper, stronger and wider outflow is more affected by the steep topography, leading to separation from the coast. While during summer, the weaker and shallower outflow is less influenced by bottom topography and so continues along the boundary.

Effects of preexisting cyclonic eddies on upper ocean responses to Category 5 typhoons in the western North Pacific

This study examines the impacts of preexisting mesoscale cyclonic eddies (PCEs) on successive enhanced sea surface cooling in response to the passage of Super Typhoon Hai‐Tang in the western North Pacific in 2005, using numerical simulation methods. We have done two numerical experiments: one with the presence of these PCEs resolved by the Hybrid Coordinate Ocean Model/Navy Coupled Ocean Data Assimilation system (EXPHYC) and another with World Ocean Atlas 2001 climatology as initial conditions (EXPWOA). The results show that the cooling response simulated by EXPWOA is only half of that simulated by EXPHYC, which is close to satellite observations. This suggests that an accurate representation of the upper dynamic conditions is required to estimate the sea surface cooling to a typhoon accurately. Subsequently, the effects of the PCEs on successive cooling response to most major typhoons are evaluated by conducting a systematical analysis with a focus on Category 5 typhoons occurring in the region from 2003 to 2008. Satellite altimeter sea surface height anomaly data and merged Tropical Rainfall Measuring Mission Microwave Imager/Advanced Microwave Scanning Radiometer for EOS microwave sea surface temperatures (SST) are used to characterize PCEs and cooling responses to those typhoons. The results identify the relationship between PCEs and successive enhanced SST cooling for most strong typhoons in the western North Pacific.

A digital temperature atlas for the Norwegian Sea

AbstractOttersen, G. 2010. A digital temperature atlas for the Norwegian Sea. – ICES Journal of Marine Science, 67: 1525–1537. The first digital temperature atlas for the Norwegian Sea (Nordic Seas/GIN Sea) is described and examples of applications given. The atlas is intended mainly to make historical temperature values available to fisheries oceanographers, fisheries biologists, and stock assessment scientists in a structured, uniform format. It should also be of interest to physical oceanographers, climate researchers, and numerical modellers, and will be of relevance to remote-sensing analyses. The atlas, made freely available for scientific non-commercial purposes, is based on interpolation from 59 496 mainly Norwegian, Faroese, and Icelandic hydrographic stations. It consists of gridded temperature fields for the area 20°W–20°E 60–80°N, with a spatial resolution of 1/2° longitude by 1/3° latitude. It covers the quarters January–March, April–June, July–September, and October–December for each year from 1990 to 2007 at 28 depth levels from 0 to 500 m. Two versions of the atlas were produced, one based solely on actual data and one where cells with “missing” values were filled from World Ocean Atlas 05 climatology. Suggested applications include the mapping of horizontal fields and vertical sections, initiation or verification of numerical models, comparisons with SST values from remote sensing, calculations within any chosen latitude–longitude–depth box, and the estimation of the ambient temperatures fish experience when the atlas is used in conjunction with information on fish distribution.

High‐resolution climatology of the northeast Atlantic using Data‐Interpolating Variational Analysis (Diva)

Numerous climatologies are available at different resolutions and cover various parts of the global ocean. Most of them have a resolution too low to represent suitably regional processes and the methods for their construction are not able to take into account the influence of physical effects (topographic constraints, boundary conditions, advection, etc.). A high‐resolution atlas for temperature and salinity is developed for the northeast Atlantic Ocean on 33 depth levels. The originality of this climatology is twofold: (1) For the data set, data are collected on all major databases and aggregated to lead to an original data collection without duplicates, richer than the World Ocean Database 2005, for the same region of interest. (2) For the method, climatological fields are constructed using the variational method Data‐Interpolating Variational Analysis. The formulation of the latter allows the consideration of coastlines and bottom topography, and has a numerical cost almost independent on the number of observations. Moreover, only a few parameters, determined in an objective way, are necessary to perform an analysis. The results show overall good agreement with the widely used World Ocean Atlas, but also reveal significant improvements in coastal areas. Error maps are generated according to different theories and emphasize the importance of data coverage for the creation of such climatological fields. Automatic outlier detection is performed, and its effects on the analysis are examined. The method presented here is very general and not dependent on the region, hence it may be applied for creating other regional atlas in different zones of the global ocean.

Where and how long ago was water in the western North Atlantic ventilated? Maximum entropy inversions of bottle data from WOCE line A20

A maximum entropy (ME) method is used to deconvolve tracer data for the joint distribution of locations and times since last ventilation. The deconvolutions utilize World Ocean Circulation Experiment line A20 repeat hydrography for CFC‐11, potential temperature, salinity, oxygen, and phosphate, as well as Global Ocean Data Analysis Project (GLODAP) radiocarbon data, combined with surface boundary conditions derived from the atmospheric history of CFC‐11 and the World Ocean Atlas 2005 and GLODAP databases. Because of the limited number of available tracers the deconvolutions are highly underdetermined, leading to large entropic uncertainties, which are quantified using the information entropy of relative to a prior distribution. Additional uncertainties resulting from data sparsity are estimated using a Monte Carlo approach and found to be of secondary importance. The ME deconvolutions objectively identify key water mass formation regions and quantify the local fraction of water of age τ or older last ventilated in each region. Ideal mean age and radiocarbon age are also estimated but found to have large entropic uncertainties that can be attributed to uncertainties in the partitioning of a given water parcel according to where it was last ventilated. Labrador/Irminger seawater (L water) is determined to be mostly less than ∼40 a old in the vicinity of the deep western boundary current (DWBC) at the northern end of A20 but several decades older where the DWBC recrosses the section further south, pointing to the importance of mixing via a multitude of eddy‐diffusive paths. Overflow water lies primarily below L water with young waters (τ ≲ 40 a) at middepth in the northern part of A20 and waters as old as ∼600 a below ∼3500 m.

Satellite observations of the seasonal sediment plume in central East China Sea

Ocean color and sea surface temperature (SST) data from the Moderate Resolution Imaging Spectroradiometer on Aqua from 2002 to 2008, wind speed data from the National Centers for Environmental Prediction, satellite-measured sea surface height anomaly (SSHA) data, and World Ocean Atlas 1998 data are analyzed to study and understand the variability of a sediment plume in the central East China Sea, as well as its mechanism for producing this plume. The plume peaks in the winter, with an areal coverage of ∼ 4 × 10 4 km 2 and the diffuse attenuation coefficient at the wavelength of 490 nm ( K d (490)) reaching over 1.5 m − 1 , and almost disappears in the summer. The increase (decrease) of SST is coincident with the K d (490) decrease (increase) during the late spring (fall) and early summer (winter). In the winter, the entire water column becomes uniform with SST ∼ 12 °C in the East China Sea, while in the summer the water column is strongly stratified with SST over ∼ 27 °C. This seasonal sediment plume is attributed to sediment resuspension due to the strong vertical mixing and convection driven by the cooling of the upper ocean and enhanced surface winds during the winter season. In addition, satellite SSHA observations also confirm that the cross-shelf circulation resulting in this plume proposed by Yuan et al. (2008) does not exist.

An Eddy-Permitting Southern Ocean State Estimate

Abstract An eddy-permitting general circulation model of the Southern Ocean is fit by constrained least squares to a large observational dataset during 2005–06. Data used include Argo float profiles, CTD synoptic sections, Southern Elephant Seals as Oceanographic Samplers (SEaOS) instrument-mounted seal profiles, XBTs, altimetric observations [Envisat, Geosat, Jason-1, and Ocean Topography Experiment (TOPEX)/Poseidon], and infrared and microwave radiometer observed sea surface temperature. An adjoint model is used to determine descent directions in minimizing a misfit function, each of whose elements has been weighted by an estimate of the observational plus model error. The model is brought into near agreement with the data by adjusting its control vector, here consisting of initial and meteorological boundary conditions. Although total consistency has not yet been achieved, the existing solution is in good agreement with the great majority of the 2005 and 2006 Southern Ocean observations and better represents these data than does the World Ocean Atlas 2001 (WOA01) climatological product. The estimate captures the oceanic temporal variability and in this respect represents a major improvement upon earlier static inverse estimates. During the estimation period, the Drake Passage volume transport is 153 ± 5 Sv (1 Sv ≡ 106 m3 s−1). The Ross and Weddell polar gyre transports are 20 ± 5 Sv and 40 ± 8 Sv, respectively. Across 32°S there is a surface meridional overturning cell of 12 ± 12 Sv, an intermediate cell of 17 ± 12 Sv, and an abyssal cell of 13 ± 6 Sv. The northward heat and freshwater anomaly transports across 30°S are −0.3 PW and 0.7 Sv, with estimated uncertainties of 0.5 PW and 0.2 Sv. The net rate of wind work is 2.1 ± 1.1 TW. Southern Ocean theories involving short temporal- and spatial-scale dynamics may now be tested with a dynamically and thermodynamically realistic general circulation model solution that is known to be compatible with the modern observational datasets.

Application of World Ocean Atlas data for estimating the relative performance of a new construction of SWRO desalination plant

Desalination offers one of the reasonable alternatives as a solution to water scarcity. Among the desalination technologies, seawater reverse osmosis (SWRO) process becomes increasingly attractive for freshwater supply with comparatively low energy consumption and cost-effective operation. In this study, a benchmark of operating Fujairah SWRO desalination plant in the United Arab Emirates is applied to assess the relative performance of a new and large plant construction in other sites. A process model was developed to simulate the performance of SWRO desalination process and to estimate its operating cost. The developed model was validated using one-year SWRO operation data obtained from Fujairah SWRO desalination plant. Temperature and salinity data were collected from World Ocean Atlas 2005, and then applied to the model to estimate the operating cost under the site-specific conditions of 9 different countries. The results of this study present that the performance of the SWRO desalination process was significantly influenced by feed water concentration (i.e., mainly salinity) and temperature, and that the total operating cost is significantly dependent of the local electricity costs. As a conclusion, World Ocean Atlas data and the benchmark provide a method of comparing the performance of various SWRO desalination systems among different countries. Furthermore the methodology is applicable to simulate the process model with site-specific water quality data and to estimate the operating cost before a new construction of SWRO desalination plant at a target area elsewhere.

Mesoscale eddies northeast of the Hawaiian archipelago from satellite altimeter observations

Enhanced mesoscale eddy activity northeast of the Hawaiian archipelago was investigated by using the high‐pass filtered satellite altimetric sea surface height (SSH) data of the past 16 years. The level of eddy kinetic energy (EKE) shows significant interannual variations, which appear well correlated to the large‐scale atmospheric wind forcing associated with the Pacific Decadal Oscillation index; the EKE levels in the area along the Subtropical Front zone in 1997–1998 and 2003–2005, for example, were three times as large as those in the low EKE years. Spectral analyses in the 3° latitude by 5° longitude subregions revealed the dominant mesoscale periods ranging from 90 days near 18°N to 180 days near 36°N. A 3‐layer quasi‐geostrophic model constrained by World Ocean Atlas 2005 climatologies was used to explore instability of the regional circulation. The analysis shows a geographical match between baroclinic instability strength and the observed RMS SSH variability and a temporal match between seasonally varying instability strength and the observed seasonal EKE modulation, and suggests that baroclinic instability by the vertically sheared, regional mean circulation provides the energy source for the enhanced eddy variability northeast of the Hawaiian archipelago.

A new approach for deriving temperature and salinity fields in the Indian Ocean using artificial neural networks

This work reports a new methodology for deriving monthly averages of temperature (T) and salinity (S) fields for the Indian Ocean based on the use of an artificial neural network (ANN). Investigation and analysis were performed for this region with two distinct datasets: (1) monthly climatological data for T and S fields (in 1° × 1° grid boxes) at standard depth levels of the World Ocean Atlas 1994 (WOA94), and; (2) heterogeneous randomly distributed in situ ARGO, ocean station data (OSD) and profiling (PFL) floats. A further numerical experiment was conducted with these two distinct datasets to train the neural network model. Nonlinear regression mapping utilizing a multilayer perceptron (MLP) is employed to tackle nonlinearity in the data. This study reveals that a feed-forward type of network with a resilient backpropagation algorithm is best suited for deriving T and S fields; this is demonstrated by independently using WOA94 and in situ data, which thus tests the robustness of the ANN model. The suppleness of the T and S fields derived from the ANN model provides the freedom to generate a new grid at any desired level with a high degree of accuracy. Comprehensive training, testing and validation exercises were performed to demonstrate the robustness of the model and the consistency of the derived fields. The study points out that the parameters derived from the ANN model using scattered, inhomogeneous in situ data show very good agreement with state-of-the-art WOA climatological data. Using this approach, improvements in ocean climatology can be expected to occur in a synergistic manner with in situ observations. Our investigation of the Indian Ocean reveals that this approach can be extended to model global oceans.

Global‐scale quantification of mineralization pathways in marine sediments: A reaction‐transport modeling approach

The global‐scale quantification of organic carbon (Corg) degradation pathways in marine sediments is difficult to achieve experimentally due to the limited availability of field data. In the present study, a numerical modeling approach is used as an alternative to quantify the major metabolic pathways of Corg oxidation (Cox) and associated fluxes of redox‐sensitive species fluxes along a global ocean hypsometry, using the seafloor depth (SFD) as the master variable. The SFD dependency of the model parameters and forcing functions is extracted from existing empirical relationships or from the NOAA World Ocean Atlas. Results are in general agreement with estimates from the literature showing that the relative contribution of aerobic respiration to Cox increases from <10% at shallow SFD to >80% in deep‐sea sediments. Sulfate reduction essentially follows an inversed SFD dependency, the other metabolic pathways (denitrification, Mn and Fe reduction) only adding minor contributions to the global‐scale mineralization of Corg. The hypsometric analysis allows the establishment of relationships between the individual terminal electron acceptor (TEA) fluxes across the sediment‐water interface and their respective contributions to the Corg decomposition process. On a global average, simulation results indicate that sulfate reduction is the dominant metabolic pathway and accounts for approximately 76% of the total Cox, which is higher than reported so far by other authors. The results also demonstrate the importance of bioirrigation for the assessment of global species fluxes. Especially at shallow SFD most of the TEAs enter the sediments via bioirrigation, which complicates the use of concentration profiles for the determination of total TEA fluxes by molecular diffusion. Furthermore, bioirrigation accounts for major losses of reduced species from the sediment to the water column prohibiting their reoxidation inside the sediment. As a result, the total carbon mineralization rate exceeds the total flux of oxygen into the sediment by a factor of 2 globally.

A decade of acoustic thermometry in the North Pacific Ocean

Over the decade 1996–2006, acoustic sources located off central California (1996–1999) and north of Kauai (1997–1999, 2002–2006) transmitted to receivers distributed throughout the northeast and north central Pacific. The acoustic travel times are inherently spatially integrating, which suppresses mesoscale variability and provides a precise measure of ray‐averaged temperature. Daily average travel times at 4‐day intervals provide excellent temporal resolution of the large‐scale thermal field. The interannual, seasonal, and shorter‐period variability is large, with substantial changes sometimes occurring in only a few weeks. Linear trends estimated over the decade are small compared to the interannual variability and inconsistent from path to path, with some acoustic paths warming slightly and others cooling slightly. The measured travel times are compared with travel times derived from four independent estimates of the North Pacific: (1) climatology, as represented by the World Ocean Atlas 2005 (WOA05); (2) objective analysis of the upper‐ocean temperature field derived from satellite altimetry and in situ profiles; (3) an analysis provided by the Estimating the Circulation and Climate of the Ocean project, as implemented at the Jet Propulsion Laboratory (JPL‐ECCO); and (4) simulation results from a high‐resolution configuration of the Parallel Ocean Program (POP) model. The acoustic data show that WOA05 is a better estimate of the time mean hydrography than either the JPL‐ECCO or the POP estimates, both of which proved incapable of reproducing the observed acoustic arrival patterns. The comparisons of time series provide a stringent test of the large‐scale temperature variability in the models. The differences are sometimes substantial, indicating that acoustic thermometry data can provide significant additional constraints for numerical ocean models.

Bringing together an ocean of information: An extensible data integration framework for biological oceanography

As increasing volumes and varieties of data are becoming available online, the challenges of accessing and using heterogeneous data resources are growing. We have developed a mediator-based data integration system called Cartel for biological oceanography data. A mediation approach is appropriate in cases where a single central warehouse is not desirable, such as when the needed data sources change frequently through time, or when there are advantages for holding heterogeneous data in their native formats. Through Cartel, data sources of a variety of types can be registered to the system, and users can query against simplified virtual schemas, without needing to know the underlying schema and computational capabilities of each data source. The system can operate on a variety of relational and geospatial data formats, and can perform joins between formats. We tested the performance of the Cartel mediator in two biological oceanography application areas, and found that the system was able to support the variety of data types needed in a typical ecology study, but that the response times were unacceptably slow when very large databases (i.e. Ocean Biogeographic Information System and the World Ocean Atlas) were used. Indexing and caching are currently being added to the system to improve response times. The mediator is an open-source product, and was developed to be a generic, extensible component available to projects developing oceanography data systems.

The 2004–2008 mean and annual cycle of temperature, salinity, and steric height in the global ocean from the Argo Program

The Argo Program has achieved 5 years of global coverage, growing from a very sparse global array of 1000 profiling floats in early 2004 to more than 3000 instruments from late 2007 to the present. Using nearly 350,000 temperature and salinity profiles, we constructed an upper-ocean climatology and monthly anomaly fields for the 5-year era, 2004–2008. A basic description of the modern upper ocean based entirely on Argo data is presented here, to provide a baseline for comparison with past datasets and with ongoing Argo data, to test the adequacy of Argo sampling of large-scale variability, and to examine the consistency of the Argo dataset with related ocean observations from other programs. The Argo 5-year mean is compared to the World Ocean Atlas, highlighting the middle and high latitudes of the southern hemisphere as a region of strong multi-decadal warming and freshening. Moreover the region is one where Argo data have contributed an enormous increment to historical sampling, and where more Argo floats are needed for documenting large-scale variability. Globally, the Argo-era ocean is warmer than the historical climatology at nearly all depths, by an increasing amount toward the sea surface; it is saltier in the surface layer and fresher at intermediate levels. Annual cycles in temperature and salinity are compared, again to WOA01, and to the National Oceanography Center air–sea flux climatology, the Reynolds SST product, and AVISO satellite altimetric height. These products are consistent with Argo data on hemispheric and global scales, but show regional differences that may either point to systematic errors in the datasets or their syntheses, to physical processes, or to temporal variability. The present work is viewed as an initial step toward integrating Argo and other climate-relevant global ocean datasets.

Upper ocean heat content in the Nordic seas

Seven years of temperature profiles are obtained from the Argo float project and are used to study the vertically integrated heat content for the Nordic seas which is broken up into the Norwegian Basin, Greenland Sea, Lofoten region, and Iceland Plateau. The World Ocean Atlas 2005 (WOA05) is used as the climatological baseline for temperature and hence heat content. Temporally and spatially averaged temperature profiles within the Norwegian and Iceland basins show good agreement between the Argo and WOA05 data sets. For the Greenland and Lofoten basins, the WOA05 data show cooler surface temperatures (by 1–2°C) but still lie within 1 standard deviation of each other over the 7‐year period. The Argo float data show circulation within each of the basins that is counterclockwise, and some of the floats eventually disperse toward the outer edges of the basins. Vertically integrated heat content from 0 to 1200 m shows similar characteristics as the WOA05 results including the timing and strength of the seasonal variability. The anomalous heat content for the Greenland and Norwegian sea basins is calculated in depth bins of 400 m. The Greenland Sea shows a warming trend over the 7 years of study, which corresponds to a temperature increase of (4.1 ± 0.3) × 10−2 °C/yr. The Norwegian Sea basin shows interannual variability in heat content for the surface layer (0–400 m) that may be related to the North Atlantic Oscillation (NAO). During an NAO+ phase, the Norwegian Basin shows a warm phase, and during an NAO− phase, the Norwegian Basin is in a cold phase; the correlation is small (r = 0.32) but different from zero correlation only at the 90% level, implying that the variability in the AHC may be due to (1) local atmospheric forcing and hence changes in heat loss, (2) atmospheric pressure differences that are not resolved by the NAO index, and (3) exchange of heat with the basin boundaries.

On the time-mean state of ocean models and the properties of long-range acoustics.

Global and regional circulation models of the ocean have the horizontal and vertical resolution required for realistic simulation of long-range acoustic propagation. These simulations offer a novel test of model accuracy, because acoustic propagation is sensitive to the vertical gradients of sound speed in the models and acoustic arrival patterns are known to have stable and universal properties. The travel time and dispersal of an arrival pattern are examples of such properties. Acoustic receptions on three long vertical line arrays from basin-scale transmissions in the North Pacific in 1996 and 1998 are used to test the acoustical properties of the time-mean state of several ocean models. The NOAA World Ocean Atlas, a global representation of the “average” ocean, yields acoustic predictions whose patterns closely match the observations, but not all ocean models accurately represent oceanic sound speed properties. Acoustical tests of a model do not necessarily require actual data, because basic acoustical properties may be derived from the World Ocean Atlas.

Development of a New Comprehensive Ocean Atlas for Indian Ocean utilizing ARGO Data

AbstractThe World Ocean Atlas (WOA), also termed ‘Levitus Climatology’, is a global ocean climatology containing monthly, seasonal and annual means of temperature (T) and salinity (S) fields at standard ocean depths. The monthly climatology for T and S is available for standard depths up to 1000 m. The database used in the preparation of this climatology (WOA) are historical records of Conductivity, Temperature and Depth (CTD) casts and other available marine observations collected in the past. The methodology used in preparation of this WOA is objective analysis which is essentially non‐synoptic and widely scattered in the space domain. We understand that ARGO data has so far not been blended with WOA, nor has its impact for improving WOA climatology been attempted. Presently, with the wealth of marine data from ARGO profilers in the Indian Ocean, we propose a new approach to reconstruct T and S fields optimally utilizing the ARGO data. Here we develop a new model using Delaunay Tessellation with QHull algorithm delivering three‐dimensional T and S fields from a non‐uniform scattered database up to a depth of 1000 m. For gaps in a data‐sparse region, we use all available quality‐checked Ocean Station Data (OSD) and Profiling Float Data (PFL) information on T and S, in addition to the existing ARGO data. The initiative here was to replace WOA data points with realistic information from ARGO and in situ data, thereby producing a new climatology atlas. We demonstrate the robustness of our approach, and the final climatology on T and S is better compared with the existing state‐of‐the‐art WOA. The advantage of the proposed methodology is the scope of improving the ocean atlas with the addition of more ARGO data in the near future. The clustered approach in modelling enables ocean parameter retrieval in geometrically disconnected regions with an option for hot restart. We believe that the new climatology will benefit the research community immensely. Copyright © 2009 Royal Meteorological Society

A Spatio-Temporal Model for Mean, Anomaly, and Trend Fields of North Atlantic Sea Surface Temperature

We consider the problem of fitting a statistical model to 30 years of sea surface temperature records collected over a large portion of the Northern Atlantic. The observations were collected sparsely in space and time with different levels of accuracy. The purpose of the model is to produce an atlas of oceanic properties, including climatological mean fields, estimates of historical trends, and a spatio-temporal reconstruction of the anomalies, i.e., the transient deviations from the climatological mean. These products are of interest to climate change and climate variability research, numerical modeling, and remote sensing analyses. Our model improves upon the current tools used by oceanographers in that it constructs instantaneous temperature fields before averaging them into the climatology, thus giving equal weight to all years in the time frame, regardless of the temporal distribution of data. It also accounts for nonisotropic and nonstationary space and time dependencies, owing to its use of discrete process convolutions. Particular attention is given to the handling of massive datasets such as the one under study. This is achieved by considering compact support kernels that allow an efficient parallelization of the Markov chain Monte Carlo method used in the estimation of the model parameters. Resulting monthly climatologies are compared with those of the World Ocean Atlas 2001, version 2. Different water masses appear better separated in our climatology, and a close link emerges between the kernels' shape and the dominating patterns of ocean currents. The subpolar and the temperate North Atlantic display opposite trends, with the former mainly cooling over the years and the latter mainly warming, especially in the Gulf Stream region. Long-term changes in annual cycles are also detected. As in any hierarchical Bayesian model, parameter estimates come with credibility intervals, which are useful to compare results with other approaches and detect areas where sampling campaigns are needed the most.