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Author Zheng, Y.; Bourassa, M. A.; Dukhovskoy, D. S. url  openurl
  Title Upper-Ocean Processes Controlling the Sea Surface Temperature in the Western Gulf of Mexico Type $loc['typeAbstract']
  Year 2018 Publication American Geophysical Union Abbreviated Journal AGU  
  Volume Fall Meeting Issue Pages  
  Keywords 4299 General or miscellaneous, OCEANOGRAPHY: GENERAL  
  Abstract This study examines the upper-ocean processes controlling the mixed layer temperature in the western Gulf of Mexico (GOM) through estimating the contributing terms in the heat equation, with an emphasis on eddies' role. The major heat contributing terms for the upper GOM were estimated using two ocean reanalysis datasets: an eddy-resolving HYbrid Coordinate Ocean Model (HYCOM) and a Simple Ocean Data Assimilation (SODA). Analysis of net surface heat fluxes from four datasets reveals that the long-term mean net surface heat flux cools the northern GOM and warms the southern GOM. Two regions are focused for analysis: an eddy-rich region where LCEs are energetic, and the southwestern Gulf where eddy activity is relatively weak and the features of near surface temperature differ from the eddy-rich region. An eddy-rich region in the western GOM is defined based on the eddy kinetic energy derived from satellite sea surface heights. The long-term mean horizontal heat advection causes a weak warming over most of the eddy rich region, partly attributed to the flow-temperature configuration that the long-term and seasonally mean flow is nearly parallel to the corresponding mean isotherms. By contrast, the temporal mean vertical heat advection causes a strong warming in the eddy rich region, partly balancing the cooling caused by net surface heat flux. The temporal mean eddy heat flux convergence in the western GOM, whose positive and negative values are not small at some locations, appears heterogeneous in space, resulting in a small term for the western GOM when area averaged. The persistent warm water in the southwestern Gulf is primarily caused by the net warming from net surface heat flux rather than from eddies and heat advection.  
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  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1007  
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Author Nyadjro, E.S.; Rydbeck, A.V.; Jensen, T.G.; Richman, J.G.; Shriver, J.F. url  doi
openurl 
  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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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-9275 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1118  
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Author Kelly, T.B.; Goericke, R.; Kahru, M.; Song, H.; Stukel, M.R. url  doi
openurl 
  Title CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection Type $loc['typeJournal Article']
  Year 2018 Publication Deep Sea Research Part I: Oceanographic Research Papers Abbreviated Journal Deep Sea Research Part I: Oceanographic Research Papers  
  Volume 140 Issue Pages 14-25  
  Keywords CALIFORNIA CURRENT ECOSYSTEM; OCEAN CARBON-CYCLE; COASTAL WATERS; FRONTAL ZONE; TIME-SERIES; FLUX; SINKING; SEA; PACIFIC; ZOOPLANKTON  
  Abstract Estimating interannual variability in carbon export is a key goal of many marine biogeochemical studies. However, due to variations in export mechanisms between regions, generalized models used to estimate global patterns in export often fail when used for intra-regional analysis. We present here a region-specific model of export production for the California Current Ecosystem (CCE) parameterized using intensive Lagrangian process studies conducted during El Niño-Southern Oscillation (ENSO) warm and neutral phases by the CCE Long-Term Ecological Research (LTER) program. We find that, contrary to expectations from prominent global algorithms, export efficiency (e-ratio = export / primary productivity) is positively correlated with temperature and negatively correlated with net primary productivity (NPP). We attribute these results to the substantial horizontal advection found within the region, and verify this assumption by using a Lagrangian particle tracking model to estimate water mass age. We further suggest that sinking particles in the CCE are comprised of a recently-produced, rapidly-sinking component (likely mesozooplankton fecal pellets) and a longer-lived, slowly-sinking component that is likely advected long distances prior to export. We determine a new algorithm for estimating particle export in the CCE from NPP (Export = 0.08 · NPP + 72 mg C m-2 d-1). We apply this algorithm to a two-decade long time series of NPP in the CCE to estimate spatial and interannual variability across multiple ENSO phases. Reduced export during the warm anomaly of 2014-2015 and El Niño 2015-2016 resulted primarily from decreased export in the coastal upwelling region of the CCE; the oligotrophic offshore region exhibited comparatively low seasonal and interannual variability in flux. The model resolves intra-regional patterns of in situ export measurements, and provides a valuable contrast to global export models.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0967-0637 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ rl18 @ Serial 984  
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Author Kelly, T.B.; Goericke, R.; Kahru, M.; Song, H.; Stukel, M.R. url  doi
openurl 
  Title CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection Type $loc['typeJournal Article']
  Year 2018 Publication Deep Sea Research Part I: Oceanographic Research Papers Abbreviated Journal Deep Sea Research Part I: Oceanographic Research Papers  
  Volume 140 Issue Pages 14-25  
  Keywords california current ecosystem; coastal waters; flux; frontal zone; ocean carbon-cycle; oceanography; pacific; sea; sinking; time-series; Zooplankton  
  Abstract  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0967-0637 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1022  
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Author Morrow, R.M.; Ohman, M.D.; Goericke, R.; Kelly, T.B.; Stephens, B.M.; Stukel, M.R. url  doi
openurl 
  Title CCE V: Primary production, mesozooplankton grazing, and the biological pump in the California Current Ecosystem: Variability and response to El Niño Type $loc['typeJournal Article']
  Year 2018 Publication Deep Sea Research Part I: Oceanographic Research Papers Abbreviated Journal Deep Sea Research Part I: Oceanographic Research Papers  
  Volume 140 Issue Pages 52-62  
  Keywords Carbon export; Fecal pellets; Sinking particles; Interannual variability; Net primary productivity; Eastern boundary upwelling system KeyWords Plus:ZOOPLANKTON FECAL PELLETS; NORTH PACIFIC-OCEAN; CURRENT SYSTEM; SOUTHERN CALIFORNIA; UNDERWATER GLIDERS; CARBON EXPORT; ZONE; CHLOROPHYLL; STABILITY; EQUATIONS  
  Abstract Predicting marine carbon sequestration in a changing climate requires mechanistic understanding of the processes controlling sinking particle flux under different climatic conditions. The recent occurrence of a warm anomaly (2014-2015) followed by an El Nino (2015-2016) in the southern sector of the California Current System presented an opportunity to analyze changes in the biological carbon pump in response to altered climate forcing. We compare primary production, mesozooplankton grazing, and carbon export from the euphotic zone during quasi-Lagrangian experiments conducted in contrasting conditions: two cruises during warm years – one during the warm anomaly in 2014 and one toward the end of El Nino 2016 – and three cruises during El Ninoneutral years. Results showed no substantial differences in the relationships between vertical carbon export and its presumed drivers (primary production, mesozooplankton grazing) between warm and neutral years. Mesozooplankton fecal pellet enumeration and phaeopigment measurements both showed that fecal pellets were the dominant contributor to export in productive upwelling regions. In more oligotrophic regions, fluxes were dominated by amorphous marine snow with negligible pigment content. We found no evidence for a significant shift in the relationship between mesozooplankton grazing rate and chlorophyll concentration. However, massspecific grazing rates were lower at low-to-moderate chlorophyll concentrations during warm years relative to neutral years. We also detected a significant difference in the relationship between phytoplankton primary production and photosynthetically active radiation between years: at similar irradiance and nutrient concentrations, productivity decreased during the warm events. Whether these changes resulted from species composition changes remains to be determined. Overall, our results suggest that the processes driving export remain similar during different climate conditions, but that species compositional changes or other structural changes require further attention.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0967-0637 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ rl18 @ Serial 983  
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Author Bhowmick, S. A.; Agarwal, N.; Ali, M. M.; Kishtawal, C. M.; Sharma, R. url  doi
openurl 
  Title Role of ocean heat content in boosting post-monsoon tropical storms over Bay of Bengal during La-Nina events Type $loc['typeJournal Article']
  Year 2019 Publication Climate Dynamics Abbreviated Journal  
  Volume 52 Issue 12 Pages 7225-7234  
  Keywords La-Niña; Bay of Bengal; Tropical cyclones; Ocean heat content  
  Abstract This study aims to analyze the role of ocean heat content in boosting the post-monsoon cyclonic activities over Bay of Bengal during La-Niña events. In strong La-Niña years, accumulated cyclone energy in Bay of Bengal is much more as compared to any other year. It is observed that during late June to October of moderate to strong La-Nina years, western Pacific is warmer. Sea surface temperature anomaly of western Pacific Ocean clearly indicates the presence of relatively warmer water mass in the channel connecting the Indian Ocean and Pacific Ocean, situated above Australia. Ocean currents transport the heat zonally from Pacific to South eastern Indian Ocean. Excess heat of the southern Indian Ocean is eventually transported to eastern equatorial Indian Ocean through strong geostrophic component of ocean current. By September the northward transport of this excess heat from eastern equatorial Indian Ocean to Bay of Bengal takes place during La-Nina years boosting the cyclonic activities thereafter.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ mfield @ Serial 71  
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Author Zou, S.; Lozier, M.S.; Xu, X. url  doi
openurl 
  Title Latitudinal Structure of the Meridional Overturning Circulation Variability on Interannual to Decadal Time Scales in the North Atlantic Ocean Type $loc['typeJournal Article']
  Year 2020 Publication Journal of Climate Abbreviated Journal J. Climate  
  Volume 33 Issue 9 Pages 3845-3862  
  Keywords Deep convection; Ocean circulation; Thermocline circulation  
  Abstract The latitudinal structure of the Atlantic meridional overturning circulation (AMOC) variability in the North Atlantic is investigated using numerical results from three ocean circulation simulations over the past four to five decades. We show that AMOC variability south of the Labrador Sea (53°N) to 25°N can be decomposed into a latitudinally coherent component and a gyre-opposing component. The latitudinally coherent component contains both decadal and interannual variabilities. The coherent decadal AMOC variability originates in the subpolar region and is reflected by the zonal density gradient in that basin. It is further shown to be linked to persistent North Atlantic Oscillation (NAO) conditions in all three models. The interannual AMOC variability contained in the latitudinally coherent component is shown to be driven by westerlies in the transition region between the subpolar and the subtropical gyre (40°–50°N), through significant responses in Ekman transport. Finally, the gyre-opposing component principally varies on interannual time scales and responds to local wind variability related to the annual NAO. The contribution of these components to the total AMOC variability is latitude-dependent: 1) in the subpolar region, all models show that the latitudinally coherent component dominates AMOC variability on interannual to decadal time scales, with little contribution from the gyre-opposing component, and 2) in the subtropical region, the gyre-opposing component explains a majority of the interannual AMOC variability in two models, while in the other model, the contributions from the coherent and the gyre-opposing components are comparable. These results provide a quantitative decomposition of AMOC variability across latitudes and shed light on the linkage between different AMOC variability components and atmospheric forcing mechanisms.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0894-8755 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1106  
Permanent link to this record
 

 
Author Stukel, M.R.; Biard, T.; Krause, J.W.; Ohman, M.D. url  doi
openurl 
  Title Large Phaeodaria in the twilight zone: Their role in the carbon cycle Type $loc['typeJournal Article']
  Year 2018 Publication Association for the Sciences of Limnology and Oceanography Abbreviated Journal  
  Volume Issue Pages  
  Keywords Carbon cycle; Ocean; Twilight zone, Rhizarian measurements; Aulosphaeridae  
  Abstract Advances in in situ imaging allow enumeration of abundant populations of large Rhizarians that compose a substantial proportion of total mesozooplankton biovolume. Using a quasi-Lagrangian sampling scheme, we quantified the abundance, vertical distributions, and sinking&#8208;related mortality of Aulosphaeridae, an abundant family of Phaeodaria in the California Current Ecosystem. Inter&#8208;cruise variability was high, with average concentrations at the depth of maximum abundance ranging from < 10 to > 300 cells m&#8722;3, with seasonal and interannual variability associated with temperature&#8208;preferences and regional shoaling of the 10°C isotherm. Vertical profiles showed that these organisms were consistently most abundant at 100&#65533;150&#8201;m depth. Average turnover times with respect to sinking were 4.7&#65533;10.9 d, equating to minimum in situ population growth rates of ~ 0.1&#65533;0.2 d&#8722;1. Using simultaneous measurements of sinking organic carbon, we find that these organisms could only meet their carbon demand if their carbon : volume ratio were ~ 1 &#956;g C mm&#8722;3. This value is substantially lower than previously used in global estimates of rhizarian biomass, but is reasonable for organisms that use large siliceous tests to inflate their cross&#8208;sectional area without a concomitant increase in biomass. We found that Aulosphaeridae alone can intercept > 20% of sinking particles produced in the euphotic zone before these particles reach a depth of 300&#8201;m. Our results suggest that the local (and likely global) carbon biomass of Aulosphaeridae, and probably the large Rhizaria overall, needs to be revised downwards, but that these organisms nevertheless play a major role in carbon flux attenuation in the twilight zone.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['yes']  
  Call Number COAPS @ user @ Serial 967  
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Author Morey, S. L.; Zavala-Hidalgo, J.; O'Brien, J. J. url  doi
openurl 
  Title The seasonal variability of continental shelf circulation in the northern and western Gulf of Mexico from a high-resolution numerical model Type $loc['typeBook Chapter']
  Year 2005 Publication New Developments in the Circulation of the Gulf of Mexico Abbreviated Journal  
  Volume Issue Pages  
  Keywords Ocean circulation&#65533; Mexico, Gulf of&#65533; Remote sensing; Ocean circulation&#65533; Mexico, Gulf of&#65533; Mathematical models  
  Abstract  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor Sturges, W.; Lugo-Fernandez, A.  
  Language Summary Language Original Title  
  Series Editor Series Title Geophys. Mongr. Ser. Abbreviated Series Title  
  Series Volume Series Issue 161 Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Funding ONR, NASA, MMS Approved $loc['no']  
  Call Number COAPS @ mfield @ Serial 852  
Permanent link to this record
 

 
Author Zavala-Hidalgo, J.; Romero-Centeno, R.; Mateos-Jasso, A.; Morey, S.L.; Martínez-López, B. url  doi
openurl 
  Title The response of the Gulf of Mexico to wind and heat flux forcing: What has been learned in recent years? Type $loc['typeJournal Article']
  Year 2014 Publication Atmósfera Abbreviated Journal Atmósfera  
  Volume 27 Issue 3 Pages 317-334  
  Keywords Gulf of Mexico; ocean surface forcing; upper ocean layer  
  Abstract  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0187-6236 ISBN Medium  
  Area Expedition Conference  
  Funding BP/Gulf of Mexico Research Initiative, NASA/OVWST Approved $loc['no']  
  Call Number COAPS @ mfield @ Serial 153  
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