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Ocean boundary current systems are key components of the climate system, are home to highly productive ecosystems, and have numerous societal impacts. Establishment of a global network of boundary current observing systems is a critical part of ongoing development of the Global Ocean Observing System. The characteristics of boundary current systems are reviewed, focusing on scientific and societal motivations for sustained observing. Techniques currently used to observe boundary current systems are reviewed, followed by a census of the current state of boundary current observing systems globally. Next steps in the development of boundary current observing systems are considered, leading to several specific recommendations.

Benthic δ13C is often used to infer past changes in ocean circulation, though the interpretation of this proxy is difficult due to data scarcity and uncertainties. We present two methods for reconstructing the δ13C signal of North Atlantic Deep Water (NADW) and Antarctic Bottom Water and calculating the average oceanic δ13C values for the Atlantic Ocean based on δ13C from benthic foraminifera. The two simple statistical models are described and tested for the Holocene and the Last Glacial Maximum. The first statistical model consists of regressions of the δ13C data, which vary quadratically with depth and linearly with latitude. It differentiates between two regions, one for NADW and another for Antarctic Bottom Water. The second method consists of a hyperbolic tangent regression, which is bound asymptotically by the water mass source region averages (end-members). To test the robustness of the statistical models, two isotope-enabled climate models, the UVic ESCM and LOVECLIM, are sampled randomly, generating “pseudoproxies.” These are then used for testing the accuracy of the statistical models against the complete climate model δ13C outputs. We quantitatively compare the average δ13C and NADW depth against the original climate model outputs. We find that both statistical approaches are robust, regardless of the spatial distribution of the pseudoproxies, with the quadratic approach better able to capture the shape of NADW δ13C signal. Hence, this method can potentially be applied to different δ13C data sets to evaluate past changes in NADW.

The paper gives an overview of the development of satellite oceanography over the past five years focusing on the most relevant issues for operational oceanography. Satellites provide key essential variables to constrain ocean models and/or serve downstream applications. New and improved satellite data sets have been developed and have directly improved the quality of operational products. The status of the satellite constellation for the last five years was, however, not optimal. Review of future missions shows clear progress and new research and development missions with a potentially large impact for operational oceanography should be demonstrated. Improvement of data assimilation techniques and developing synergetic use of high resolution satellite observations are important future priorities.

Recent advances in Coastal Ocean Forecasting Systems (COFS) are discussed. Emphasis is given in the integration of the observational and modeling components, each developed in the context of monitoring and forecasting in the coastal seas. These integrated systems must be linked to larger scale systems toward seamless data sets, nowcasts and forecasts (from the global ocean, through the continental shelf and to the nearshore regions). Emerging capabilities include: methods to optimize coastal/regional observational networks; and probabilistic approaches to address both science and applications related to COFS. International collaboration is essential to exchange best practices, achieve common frameworks and establish standards.

The Chesapeake Bay plays an important role in transforming riverine nutrients before they are exported to the adjacent continental shelf. Although the mean nitrogen budget of the Chesapeake Bay has been previously estimated from observations, uncertainties associated with interannually varying hydrological conditions remain. In this study, a land-estuarine-ocean biogeochemical modeling system is developed to quantify Chesapeake riverine nitrogen inputs, within-estuary nitrogen transformation processes and the ultimate export of nitrogen to the coastal ocean. Model skill was evaluated using extensive in situ and satellite-derived data, and a simulation using environmental conditions for 2001-2005 was conducted to quantify the Chesapeake Bay nitrogen budget. The 5 year simulation was characterized by large riverine inputs of nitrogen (154 × 109 g N yr-1) split roughly 60:40 between inorganic:organic components. Much of this was denitrified (34 × 109 g N yr-1) and buried (46 × 109 g N yr-1) within the estuarine system. A positive net annual ecosystem production for the bay further contributed to a large advective export of organic nitrogen to the shelf (91 × 109 g N yr-1) and negligible inorganic nitrogen export. Interannual variability was strong, particularly for the riverine nitrogen fluxes. In years with higher than average riverine nitrogen inputs, most of this excess nitrogen (50-60%) was exported from the bay as organic nitrogen, with the remaining split between burial, denitrification, and inorganic export to the coastal ocean. In comparison to previous simulations using generic shelf biogeochemical model formulations inside the estuary, the estuarine biogeochemical model described here produced more realistic and significantly greater exports of organic nitrogen and lower exports of inorganic nitrogen to the shelf.

The paper gives an overview of the development of satellite oceanography over the past five years focusing on the most relevant issues for operational oceanography. Satellites provide key essential variables to constrain ocean models and/or serve downstream applications. New and improved satellite data sets have been developed and have directly improved the quality of operational products. The status of the satellite constellation for the last five years was, however, not optimal. Review of future missions shows clear progress and new research and development missions with a potentially large impact for operational oceanography should be demonstrated. Improvement of data assimilation techniques and developing synergetic use of high resolution satellite observations are important future priorities.

The use of single-nucleotide polymorphisms (SNPs) as molecular markers in plant studies has become increasingly common. With the development of these markers, there is an interest in determining levels of variation in natural populations. Here, we identify and characterize levels of SNPs in wild populations of aspen ( Populus tremuloides Michx.). Four populations were sampled from Alberta and British Columbia in Western Canada. A total of 35 gene regions were selected for analysis. The loci selected are mainly involved in wood formation and include regions from genes for lignin biosynthesis, cellulose biosynthesis, and other cell wall compounds and a number of transcription factors. Other genes included those coding for growth hormones, disease resistance, and light responses. Primers were developed from conserved regions in multi-species EST alignments. Regions were PCR amplified, and products (approximately 500 to 1,000 bp) were assessed for levels of SNPs using Ecotilling. From a total of approximately 25 kb 462 SNPs were identified, over 18 SNPs/kb. Thus, SNPs are an abundant and potentially useful molecular marker in aspen. Gene diversity (heterozygosity) varied in the gene regions, with an overall average of H = 0.18. Although gene diversity was considerable, genetic differentiation was low with the overall F value being 0.004. A surrogate measure of linkage disequilibrium (LD) was calculated, and overall, the LD was shown to decay relatively rapidly with distance along the gene region. The results obtained from the wood formation genes in this study will enable further targeting of regions for association studies on lignin and cellulose variation in aspen and other Populus species.