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Author
Ali, M. ; Singh, N. ; Kumar, M. ; Zheng, Y. ; Bourassa, M. ; Kishtawal, C. ; Rao, C.
Title
Dominant Modes of Upper Ocean Heat Content in the North Indian Ocean
Type
$loc['typeJournal Article']
Year
2018
Publication
Climate
Abbreviated Journal
Climate
Volume
6
Issue
3
Pages
71
Keywords
ocean heat content ; tropical cyclone heat potential ; dominant modes ; North Indian Ocean ; SUMMER MONSOON ; INTENSIFICATION ; INTENSITY ; PACIFIC
Abstract
The thermal energy needed for the development of hurricanes and monsoons as well as any prolonged marine weather event comes from layers in the upper oceans, not just from the thin layer represented by sea surface temperature alone. Ocean layers have different modes of thermal energy variability because of the different time scales of ocean-atmosphere interaction. Although many previous studies have focused on the influence of upper ocean heat content (OHC) on tropical cyclones and monsoons, no study thus farparticularly in the North Indian Ocean (NIO)has specifically concluded the types of dominant modes in different layers of the ocean. In this study, we examined the dominant modes of variability of OHC of seven layers in the NIO during 1998-2014. We conclude that the thermal variability in the top 50 m of the ocean had statistically significant semiannual and annual modes of variability, while the deeper layers had the annual mode alone. Time series of OHC for the top four layers were analyzed separately for the NIO, Arabian Sea, and Bay of Bengal. For the surface to 50 m layer, the lowest and the highest values of OHC were present in January and May every year, respectively, which was mainly caused by the solar radiation cycle.
Address
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Thesis
Publisher
Place of Publication
Editor
Language
Summary Language
Original Title
Series Editor
Series Title
Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
2225-1154
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ rl18 @
Serial
986
Permanent link to this record
Author
Stukel, M.R. ; Benitez-Nelson, C.R. ; Decima, M. ; Taylor, A.G. ; Buchwald, C. ; Landry, M.R.
Title
The biological pump in the Costa Rica Dome: an open-ocean upwelling system with high new production and low export
Type
$loc['typeJournal Article']
Year
2016
Publication
Journal of Plankton Research
Abbreviated Journal
J Plankton Res
Volume
38
Issue
2
Pages
348-365
Keywords
Eastern Tropical Pacific ; biogeochemistry ; carbon flux ; nutrients ; plankton
Abstract
The Costa Rica Dome is a picophytoplankton-dominated, open-ocean upwelling system in the Eastern Tropical Pacific that overlies the ocean's largest oxygen minimum zone. To investigate the efficiency of the biological pump in this unique area, we used shallow (90-150 m) drifting sediment traps and 234Th:238U deficiency measurements to determine export fluxes of carbon, nitrogen and phosphorus in sinking particles. Simultaneous measurements of nitrate uptake and shallow water nitrification allowed us to assess the equilibrium balance of new and export production over a monthly timescale. While f-ratios (new:total production) were reasonably high (0.36 +/- 0.12, mean +/- standard deviation), export efficiencies were considerably lower. Sediment traps suggested e-ratios (export/14C-primary production) at 90-100 m ranging from 0.053 to 0.067. ThE-ratios (234Th disequilibrium-derived export) ranged from 0.038 to 0.088. C:N and N:P stoichiometries of sinking material were both greater than canonical (Redfield) ratios or measured C:N of suspended particulates, and they increased with depth, suggesting that both nitrogen and phosphorus were preferentially remineralized from sinking particles. Our results are consistent with an ecosystem in which mesozooplankton play a major role in energy transfer to higher trophic levels but are relatively inefficient in mediating vertical carbon flux to depth, leading to an imbalance between new production and sinking flux.
Address
Scripps Institution of Oceanography , University of California at San Diego , La Jolla, CA 92037 , USA
Corporate Author
Thesis
Publisher
Place of Publication
Editor
Language
English
Summary Language
Original Title
Series Editor
Series Title
Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
0142-7873
ISBN
Medium
Area
Expedition
Conference
Funding
PMID:27275035; PMCID:PMC4889986
Approved
$loc['no']
Call Number
COAPS @ mfield @
Serial
90
Permanent link to this record
Author
Morrow, R.M. ; Ohman, M.D. ; Goericke, R. ; Kelly, T.B. ; Stephens, B.M. ; Stukel, M.R.
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
Permanent link to this record
Author
Kelly, T.B. ; Goericke, R. ; Kahru, M. ; Song, H. ; Stukel, M.R.
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
Permanent link to this record
Author
Kelly, T.B. ; Goericke, R. ; Kahru, M. ; Song, H. ; Stukel, M.R.
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
Permanent link to this record
Author
Kim, D. ; Lee, S.-K. ; Lopez, H. ; Foltz, G.R. ; Misra, V. ; Kumar, A.
Title
On the Role of Pacific-Atlantic SST Contrast and Associated Caribbean Sea Convection in August-October U.S. Regional Rainfall Variability
Type
$loc['typeJournal Article']
Year
2020
Publication
Geophysical Research Letters
Abbreviated Journal
Geophys. Res. Lett.
Volume
47
Issue
11
Pages
Keywords
Pacific‐ ; Atlantic SST interaction ; Atlantic Warm pool ; Caribbean Sea ; U.S. precipitation
Abstract
This study investigates the large‐scale atmospheric processes that lead to U.S. precipitation variability in late summer to midfall (August–October; ASO) and shows that the well‐recognized relationship between North Atlantic Subtropical High and U.S. precipitation in peak summer (June–August) significantly weakens in ASO. The working hypothesis derived from our analysis is that in ASO convective activity in the Caribbean Sea, modulated by the tropical Pacific‐Atlantic sea surface temperature (SST) anomaly contrast, directly influences the North American Low‐Level Jet and thus U.S. precipitation east of the Rockies, through a Gill‐type response. This hypothesis derived from observations is strongly supported by a long‐term climate model simulation and by a linear baroclinic atmospheric model with prescribed diabatic forcings in the Caribbean Sea. This study integrates key findings from previous studies and advances a consistent physical rationale that links the Pacific‐Atlantic SST anomaly contrast, Caribbean Sea convective activity, and U.S. rainfall in ASO.
Address
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Thesis
Publisher
Place of Publication
Editor
Language
Summary Language
Original Title
Series Editor
Series Title
Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
0094-8276
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1110
Permanent link to this record
Author
Zhao, X. ; Zhou, C. ; Xu, X. ; Ye, R. ; Tian, J. ; Zhao, W.
Title
Deep Circulation in the South China Sea Simulated in a Regional Model
Type
$loc['typeJournal Article']
Year
2019
Publication
Ocean Sci. Discuss
Abbreviated Journal
Ocean Sci. Discuss
Volume
Issue
Pages
Keywords
Sea Marine, Oceanography/CIMST, PacificOcean, continuous current-meter, deep circulation, deep western boundary
Abstract
The South China Sea (SCS) is the largest marginal sea in the northwest Pacific Ocean. In this study, deep circulation in the SCS is investigated using results from eddy-resolving, regional simulations using the Hybrid Coordinate Ocean Model (HYCOM) verified by continuous current-meter observations. Analysis of these results provides a detailed spatial structure and temporal variability of the deep circulation in the SCS. The major features of the SCS deep circulation are a basin-scale cyclonic gyre and a concentrated deep western boundary current (DWBC). Transport of the DWBC is ∼ 2 Sv at 16.5° N with a width of ∼53 km. Flowing southwestward, the narrow DWBC becomes weaker with a wider range. The model results reveal the existence of 80- to 120-day oscillation in the deep northeastern circulation and the DWBC, which are also the areas with elevated eddy kinetic energy. This intraseasonal oscillation propagates northwestward with a velocity amplitude of ∼ 1.0 to 1.5 cm s-1. The distribution of mixing parameters in the deep SCS plays a role in both spatial structure and volume transport of the deep circulation. Compared with the northern shelf of the SCS with the Luzon Strait, deep circulation in the SCS is more sensitive to the large vertical mixing parameters of the Zhongsha Island Chain area.
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Publisher
Place of Publication
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Language
Summary Language
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Medium
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Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1013
Permanent link to this record