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| Author | Neto, A.G.; Palter, J.; Bower, A.; Furey, H.; Xu. X. | ||||
| Title | Labrador Sea Water transport across the Charlie-Gibbs Fracture Zone | Type | $loc['typeJournal Article'] | ||
| Year | 2020 | Publication | Journal of Geophysical Research: Oceans | Abbreviated Journal | J. Geophys. Res. Oceans |
| Volume | Accepted | Issue | Pages | ||
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| Abstract | Labrador Sea Water (LSW) is a major component of the deep limb of the Atlantic Meridional Overturning Circulation, yet LSW transport pathways and their variability lack a complete description. A portion of the LSW exported from the subpolar gyre is advected eastward along the North Atlantic Current and must contend with the Mid‐Atlantic Ridge before reaching the eastern basins of the North Atlantic. Here, we analyze observations from a mooring array and satellite altimetry, together with outputs from a hindcast ocean model simulation, to estimate the mean transport of LSW across the Charlie Gibbs Fracture Zone (CGFZ), a primary gateway for the eastward transport of the water mass. The LSW transport estimated from the 25‐year altimetry record is 5.3 ± 2.9 Sv, where the error represents the combination of observational variability and the uncertainty in the projection of the surface velocities to the LSW layer. Current velocities modulate the interannual to higher frequency variability of the LSW transport at the CGFZ, while the LSW thickness becomes important on longer time scales. The modeled mean LSW transport for 1993‐2012 is higher than the estimate from altimetry, at 8.2 ± 4.1 Sv. The modeled LSW thickness decreases substantially at the CGFZ between 1996 and 2009, consistent with an observed decline in LSW volume in the Labrador Sea after 1994. We suggest that satellite altimetry and continuous hydrographic measurements in the central Labrador Sea, supplemented by profiles from Argo floats, could be sufficient to quantify the LSW transport at the CGFZ. | ||||
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| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1108 | ||
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| Author | Nyadjro, E.S.; Rydbeck, A.V.; Jensen, T.G.; Richman, J.G.; Shriver, J.F. | ||||
| Title | On the Generation and Salinity Impacts of Intraseasonal Westward Jets in the Equatorial Indian Ocean | Type | $loc['typeJournal Article'] | ||
| Year | 2020 | Publication | Journal of Geophysical Research: Oceans | Abbreviated Journal | J. Geophys. Res. Oceans |
| Volume | 125 | Issue | 6 | Pages | e2020JC016066 |
| Keywords | ndian Ocean; intraseasonal variability; westward Jet; intraseasonal oscillations; mixed layer salinity; surface currents | ||||
| Abstract | While westerly winds dominate the equatorial Indian Ocean and generate the well‐known eastward flowing Wyrtki Jets during boreal spring and fall, there is evidence of a strong westward surface jet during winter that is swifter than eastward currents during that season. A weaker westward jet is found in summer. In this study, we report the occurrence, characteristics, and intraseasonal variability of this westward jet and its impact on mixed layer salinity in the equatorial Indian Ocean using the HYbrid Coordinate Ocean Model (HYCOM) reanalysis with the Navy Coupled Ocean Data Assimilation (NCODA). The westward jet typically occurs in the upper 50 m, above an eastward flowing equatorial undercurrent, with peak westward volume transport of approximately −8 Sv. The westward jet builds up gradually, decays rapidly, and is primarily forced by local intraseasonal wind stress anomalies generated by atmospheric intraseasonal convection. Westward acceleration of the jet occurs when the dominant intraseasonal westward wind anomaly is not balanced by the zonal pressure gradient (ZPG) force. The intraseasonal westward jet generates strong horizontal advection and is the leading cause of mixed layer freshening in the western equatorial Indian Ocean. Without it, a saltier mixed layer would persist and weaken any barrier layers. Existing barrier layers are strengthened following the passage of freshwater‐laden westward jets. Deceleration of the westward jet occurs when the eastward ZPG becomes increasingly important and the westward intraseasonal wind anomalies weaken. A rapid reversal of atmospheric intraseasonal convection‐driven surface winds eventually terminates the westward jet. | ||||
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| ISSN | 2169-9275 | ISBN | Medium | ||
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| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1118 | ||
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| Author | Parfitt, R.; Ummenhofer, C.C.; Buckley, B.M.; Hansen, K.G.; D'Arrigo, R.D. | ||||
| Title | Distinct seasonal climate drivers revealed in a network of tree-ring records from Labrador, Canada | Type | $loc['typeJournal Article'] | ||
| Year | 2020 | Publication | Climate Dynamics | Abbreviated Journal | Clim Dyn |
| Volume | 54 | Issue | 3-4 | Pages | 1897-1911 |
| Keywords | BLUE INTENSITY; LATEWOOD DENSITY; TEMPERATURE; DENDROCLIMATOLOGY; PRECIPITATION; STANDARDIZATION; VARIABILITY; NUNATSIAVUT; TRENDS; GULF | ||||
| Abstract | Traditionally, high-latitude dendroclimatic studies have focused on measurements of total ring width (RW), with the maximum density of the latewood (MXD) serving as a complementary variable. Whilst MXD has typically improved the strength of the growing season climate connection over that of RW, its measurements are costly and time-consuming. Recently, a less costly and more time-efficient technique to extract density measurements has emerged, based on lignin's propensity to absorb blue light. This Blue Intensity (BI) methodology is based on image analyses of finely-sanded core samples, and the relative ease with which density measurements can be extracted allows for significant increases in spatio-temporal sample depth. While some studies have attempted to combine RW and MXD as predictors for summer temperature reconstructions, here we evaluate a systematic comparison of the climate signal for RW and latewood BI (LWBI) separately, using a recently updated and expanded tree ring database for Labrador, Canada. We demonstrate that while RW responds primarily to climatic drivers earlier in the growing season (January-April), LWBI is more responsive to climate conditions during late spring and summer (May-August). Furthermore, RW appears to be driven primarily by large-scale atmospheric dynamics associated with the Pacific North American pattern, whilst LWBI is more closely associated with local climate conditions, themselves linked to the behaviour of the Atlantic Multidecadal Oscillation. Lastly, we demonstrate that anomalously wide or narrow growth rings consistently respond to the same climate drivers as average growth years, whereas the sensitivity of LWBI to extreme climate conditions appears to be enhanced. | ||||
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| ISSN | 0930-7575 | ISBN | Medium | ||
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| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1119 | ||
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| Author | Proshutinsky, A.; Krishfield, R.; Toole, J.M.; Timmermans, M.-L.; Williams, W.; Zimmermann, S.; Yamamoto-Kawai, M.; Armitage, T.W.K.; Dukhovskoy, D.; Golubeva, E.; Manucharyan, G.E.; Platov, G.; Watanabe, E.; Kikuchi, T.; Nishino, S.; Itoh, M.; Kang, S.-H.; Cho, K.-H.; Tateyama, K.; Zhao, J. | ||||
| Title | Analysis of the Beaufort Gyre Freshwater Content in 2003-2018 | Type | $loc['typeJournal Article'] | ||
| Year | 2019 | Publication | Abbreviated Journal | J Geophys Res Oceans | |
| Volume | 124 | Issue | 12 | Pages | |
| Keywords | Arctic Ocean; Beaufort Gyre; circulation; climate change; freshwater balance; modeling | ||||
| Abstract | Hydrographic data collected from research cruises, bottom-anchored moorings, drifting Ice-Tethered Profilers, and satellite altimetry in the Beaufort Gyre region of the Arctic Ocean document an increase of more than 6,400 km(3) of liquid freshwater content from 2003 to 2018: a 40% growth relative to the climatology of the 1970s. This fresh water accumulation is shown to result from persistent anticyclonic atmospheric wind forcing (1997-2018) accompanied by sea ice melt, a wind-forced redirection of Mackenzie River discharge from predominantly eastward to westward flow, and a contribution of low salinity waters of Pacific Ocean origin via Bering Strait. Despite significant uncertainties in the different observations, this study has demonstrated the synergistic value of having multiple diverse datasets to obtain a more comprehensive understanding of Beaufort Gyre freshwater content variability. For example, Beaufort Gyre Observational System (BGOS) surveys clearly show the interannual increase in freshwater content, but without satellite or Ice-Tethered Profiler measurements, it is not possible to resolve the seasonal cycle of freshwater content, which in fact is larger than the year-to-year variability, or the more subtle interannual variations. | ||||
| Address | Physical Oceanography Laboratory Ocean University of China, Qingdao China | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 2169-9275 | ISBN | Medium | ||
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| Funding | strtoupper('3').strtolower('2055432'); strtoupper('P').strtolower('MC7003849') | Approved | $loc['no'] | ||
| Call Number | COAPS @ user @ | Serial | 1097 | ||
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| Author | Proshutinsky, A.; Krishfield, R.; Toole, J.M.; Timmermans, M.-L.; Williams, W.; Zimmermann, S.; Yamamoto-Kawai, M.; Armitage, T.W.K.; Dukhovskoy, D.; Golubeva, E.; Manucharyan, G.E.; Platov, G.; Watanabe, E.; Kikuchi, T.; Nishino, S.; Itoh, M.; Kang, S.-H.; Cho, K.-H.; Tateyama, K.; Zhao, J. | ||||
| Title | Analysis of the Beaufort Gyre Freshwater Content in 2003-2018 | Type | $loc['typeJournal Article'] | ||
| Year | 2019 | Publication | Abbreviated Journal | J Geophys Res Oceans | |
| Volume | 124 | Issue | 12 | Pages | 9658-9689 |
| Keywords | Arctic Ocean; Beaufort Gyre; circulation; climate change; freshwater balance; modeling | ||||
| Abstract | Hydrographic data collected from research cruises, bottom-anchored moorings, drifting Ice-Tethered Profilers, and satellite altimetry in the Beaufort Gyre region of the Arctic Ocean document an increase of more than 6,400 km(3) of liquid freshwater content from 2003 to 2018: a 40% growth relative to the climatology of the 1970s. This fresh water accumulation is shown to result from persistent anticyclonic atmospheric wind forcing (1997-2018) accompanied by sea ice melt, a wind-forced redirection of Mackenzie River discharge from predominantly eastward to westward flow, and a contribution of low salinity waters of Pacific Ocean origin via Bering Strait. Despite significant uncertainties in the different observations, this study has demonstrated the synergistic value of having multiple diverse datasets to obtain a more comprehensive understanding of Beaufort Gyre freshwater content variability. For example, Beaufort Gyre Observational System (BGOS) surveys clearly show the interannual increase in freshwater content, but without satellite or Ice-Tethered Profiler measurements, it is not possible to resolve the seasonal cycle of freshwater content, which in fact is larger than the year-to-year variability, or the more subtle interannual variations. | ||||
| Address | Physical Oceanography Laboratory Ocean University of China, Qingdao China | ||||
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| Language | English | Summary Language | Original Title | ||
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| ISSN | 2169-9275 | ISBN | Medium | ||
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| Funding | strtoupper('3').strtolower('2055432'); strtoupper('P').strtolower('MC7003849') | Approved | $loc['no'] | ||
| Call Number | COAPS @ user @ | Serial | 1102 | ||
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| Author | Rahaman, H.; Srinivasu, U.; Panickal, S.; Durgadoo, J.V.; Griffies, S.M.; Ravichandran, M.; Bozec, A.; Cherchi, A.; Voldoire, A.; Sidorenko, D..; Chassignet, E.P.; Danabasoglu, G.; Tsujino, H.; Getzlaff, K.; Ilicak, M.; Bentsen, M.; Long, M.C.; Fogli, P.G.; Farneti, R.; Danilov, S.; Marsland, S.J.; Valcke, S.; Yeager, S.G.; Wang, Q. | ||||
| Title | An assessment of the Indian Ocean mean state and seasonal cycle in a suite of interannual CORE-II simulations | Type | $loc['typeJournal Article'] | ||
| Year | 2020 | Publication | Ocean Modelling | Abbreviated Journal | Ocean Modelling |
| Volume | 145 | Issue | Pages | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 1463-5003 | ISBN | Medium | ||
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| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1087 | ||
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| Author | Roberts, M.J.; Jackson, L.C.; Roberts, C.D.; Meccia, V.; Docquier, D.; Koenigk, T.; Ortega, P.; Moreno‐ Chamarro, E.; Bellucci, A.; Coward, A.; Drijfhout, S.; Exarchou, E.; Gutjahr, O.; Hewitt, H.; Iovino, D.; Lohmann, K.; Putrasahan, D.; Schiemann, R.; Seddon, J.; Terray, L.; Xu, X.; Zhang, Q.; Chang, P.; Yeager, S.G.; Castruccio, F.S.; Zhang. C.; Wu, L. | ||||
| Title | Sensitivity of the Atlantic Meridional Overturning Circulation to Model Resolution in CMIP6 HighResMIP Simulations and Implications for Future Changes | Type | $loc['typeJournal Article'] | ||
| Year | 2020 | Publication | Journal of Advances in Modeling Earth Systems | Abbreviated Journal | J. Adv. Model. Earth Syst. |
| Volume | Issue | Pages | Accepted | ||
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| Abstract | A multi‐model, multi‐resolution ensemble using CMIP6 HighResMIP coupled experiments is used to assess the performance of key aspects of the North Atlantic circulation. The Atlantic Meridional Overturning Circulation (AMOC), and related heat transport, tends to become stronger as ocean model resolution is enhanced, better agreeing with observations at 26.5°N. However for most models the circulation remains too shallow compared to observations, and has a smaller temperature contrast between the northward and southward limbs of the AMOC. These biases cause the northward heat transport to be systematically too low for a given overturning strength. The higher resolution models also tend to have too much deep mixing in the subpolar gyre. In the period 2015‐2050 the overturning circulation tends to decline more rapidly in the higher resolution models, which is related to both the mean state and to the subpolar gyre contribution to deep water formation. The main part of the decline comes from the Florida Current component of the circulation. Such large declines in AMOC are not seen in the models with resolutions more typically used for climate studies, suggesting an enhanced risk for Northern Hemisphere climate change. However, only a small number of different ocean models are included in the study. |
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| Call Number | COAPS @ user @ | Serial | 1109 | ||
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| Author | Rodríguez, E.; Bourassa, M.; Chelton, D.; Farrar, J.T.; Long, D.; Perkovic-Martin, D.; Samelson, R. | ||||
| Title | The Winds and Currents Mission Concept | Type | $loc['typeJournal Article'] | ||
| Year | 2019 | Publication | Frontiers in Marine Science | Abbreviated Journal | Front. Mar. Sci. |
| Volume | 6 | Issue | Pages | ||
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| Abstract | The Winds and Currents Mission (WaCM) is a proposed approach to meet the need identified by the NRC Decadal Survey for the simultaneous measurements of ocean vector winds and currents. WaCM features a Ka-band pencil-beam Doppler scatterometer able to map ocean winds and currents globally. We review the principles behind the WaCM measurement and the requirements driving the mission. We then present an overview of the WaCM observatory and tie its capabilities to other OceanObs reviews and measurement approaches. | ||||
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| ISSN | 2296-7745 | ISBN | Medium | ||
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| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1063 | ||
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| Author | Shropshire, T.; Morey, S. L.; Chassignet, E. P.; Bozec, A.; Coles, V.J.; Landry, M.R.; Swalethorp, R.; Zapfe, G. and Stukel, M.R. | ||||
| Title | Quantifying spatiotemporal variability in zooplankton dynamics in the Gulf of Mexico with a physical-biogeochemical model | Type | $loc['typeJournal Article'] | ||
| Year | 2019 | Publication | Abbreviated Journal | ||
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| Abstract | Zooplankton play an important role in global biogeochemistry and their secondary production supports valuable fisheries of the world's oceans. Currently, zooplankton abundances cannot be estimated using remote sensing techniques. Hence, coupled physical-biogeochemical models (PBMs) provide an important tool for studying zooplankton on regional and global scales. However, evaluating the accuracy of zooplankton abundance estimates from PBMs has been a major challenge as a result of sparse observations. In this study, we configure a PBM for the Gulf of Mexico (GoM) from 1993�2012 and validate the model against an extensive combination of in situ biomass and rate measurements including total mesozooplankton biomass, size-fractionated mesozooplankton biomass and grazing rates, microzooplankton specific grazing rates, surface chlorophyll, deep chlorophyll maximum depth, phytoplankton specific growth rates, and net primary production. Spatial variability in mesozooplankton biomass climatology observed in a multi-decadal database for the northern GoM is well resolved by the model with a statistically significant (p < 0.01) correlation of 0.90. Mesozooplankton secondary production for the region averaged 66 + 8 mt C yr−1 equivalent to approximately 10 % of NPP and ranged from 51 to 82 mt C yr−1. In terms of diet, model results from the shelf regions suggest that herbivory is the dominant feeding mode for small mesozooplankton (< 1-mm) whereas larger mesozooplankton are primarily carnivorous. However, in open-ocean, oligotrophic regions, both groups of mesozooplankton have proportionally greater reliance on heterotrophic protists as a food source. This highlights the important role of microbial and protistan food webs in sustaining mesozooplankton biomass in the GoM which serves as the primary food source for early life stages of many commercially-important fish species, including tuna. | ||||
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| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1095 | ||
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| Author | Stukel, M.R.; Barbeau, K.A. | ||||
| Title | Investigating the Nutrient Landscape in a Coastal Upwelling Region and Its Relationship to the Biological Carbon Pump | Type | $loc['typeJournal Article'] | ||
| Year | 2020 | Publication | Geophysical Research Letters | Abbreviated Journal | Geophys. Res. Lett. |
| Volume | 47 | Issue | 6 | Pages | e2020GL087351 |
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| Abstract | We investigated nutrient patterns and their relationship to vertical carbon export using results from 38 Lagrangian experiments in the California Current Ecosystem. The dominant mode of variability reflected onshore-offshore nutrient gradients. A secondary mode of variability was correlated with silica excess and dissolved iron and likely reflects regional patterns of iron-limitation. The biological carbon pump was enhanced in high nutrient and Fe-stressed regions. Patterns in the nutrient landscape proved to be better predictors of the vertical flux of sinking particles than contemporaneous measurements of net primary production. Our results suggest an important role for Fe-stressed diatoms in vertical carbon flux. They also suggest that either preferential recycling of N or non-Redfieldian nutrient uptake by diatoms may lead to high PO:NO and Si(OH):NO ratios, following export of P- and Si-enriched organic matter. Increased export following Fe-stress may partially explain inverse relationships between net primary productivity and export efficiency. | ||||
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| ISSN | 0094-8276 | ISBN | Medium | ||
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| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1112 | ||
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