Illustrative Visualization of Mesoscale Ocean Eddies

2017 ◽  
Vol 36 (3) ◽  
pp. 447-458 ◽  
Author(s):  
L. Liu ◽  
D. Silver ◽  
K. Bemis ◽  
D. Kang ◽  
E. Curchitser
Keyword(s):  
Ocean Eddies ◽  
Mesoscale Ocean Eddies ◽  
Illustrative Visualization

scholarly journals Clustering Complex Trajectories Based on Topologic Similarity and Spatial Proximity: A Case Study of the Mesoscale Ocean Eddies in the South China Sea

2019 ◽  
Vol 8 (12) ◽  
pp. 574 ◽  
Author(s):  
Huimeng Wang ◽  
Yunyan Du ◽  
Yong Sun ◽  
Fuyuan Liang ◽  
Jiawei Yi ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
Spatial Proximity ◽  
The South ◽  
Ocean Eddies ◽  
China Sea ◽  
Mesoscale Ocean Eddies ◽  
Complex Trajectories ◽  
Global Similarity

Many real-world dynamic features such as ocean eddies, rain clouds, and air masses may split or merge while they are migrating within a space. Topologically, the migration trajectories of such features are structurally more complex as they may have multiple branches due to the splitting and merging processes. Identifying the spatial aggregation patterns of the trajectories could help us better understand how such features evolve. We propose a method, a Global Similarity Measuring Algorithm for the Complex Trajectories (GSMCT), to examine the spatial proximity and topologic similarity among complex trajectories. The method first transforms the complex trajectories into graph structures with nodes and edges. The global similarity between two graph structures (i.e., two complex trajectories) is calculated by averaging their topologic similarity and the spatial proximity, which are calculated using the Comprehensive Structure Matching (CSM) and the Hausdorff distance (HD) methods, respectively. We applied the GSMCT, the HD, and the Dynamic Time Warping (DTW) methods to examine the complex trajectories of the 1993–2016 mesoscale eddies in the South China Sea (SCS). Based on the similarity evaluation results, we categorized the complex trajectories across the SCS into four groups, which are similar to the zoning results reported in previous studies, though difference exists. Moreover, the yearly numbers of complex trajectories in the clusters in the northernmost (Cluster 1) and the southernmost SCS (Cluster 4) are almost the same. However, their seasonal variation and migration characteristics are totally opposite. Such new knowledge is very useful for oceanographers of interest to study and numerically simulate the mesoscale ocean eddies in the SCS.

scholarly journals Major migration corridors of mesoscale ocean eddies in the South China Sea from 1992 to 2012

2016 ◽  
Vol 158 ◽  
pp. 173-181 ◽  
Author(s):  
Yunyan Du ◽  
Di Wu ◽  
Fuyuan Liang ◽  
Jiawei Yi ◽  
Yang Mo ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
Ocean Eddies ◽  
China Sea ◽  
Migration Corridors ◽  
Mesoscale Ocean Eddies

scholarly journals Chaotic variability of the meridional overturning circulation on subannual to interannual timescales

Ocean Science ◽  
2013 ◽  
Vol 9 (5) ◽  
pp. 805-823 ◽  
Author(s):  
J. J.-M. Hirschi ◽  
A. T. Blaker ◽  
B. Sinha ◽  
A. Coward ◽  
B. de Cuevas ◽  
...  
Keyword(s):  
Initial Conditions ◽  
Large Fraction ◽  
Mesoscale Eddy ◽  
Surface Fluxes ◽  
Meridional Overturning Circulation ◽  
Global Ocean ◽  
Overturning Circulation ◽  
Ocean Eddies ◽  
Mesoscale Ocean Eddies ◽  
Meridional Overturning

Abstract. Observations and numerical simulations have shown that the meridional overturning circulation (MOC) exhibits substantial variability on sub- to interannual timescales. This variability is not fully understood. In particular it is not known what fraction of the MOC variability is caused by processes such as mesoscale ocean eddies and waves which are ubiquitous in the ocean. Here we analyse twin experiments performed with a global ocean model at eddying (1/4°) and non-eddying (1°) resolutions. The twin experiments are forced with the same surface fluxes for the 1958 to 2001 period but start from different initial conditions. Our results show that on subannual to interannual timescales a large fraction of MOC variability directly reflects variability in the surface forcing. Nevertheless, in the eddy-permitting case there is an initial-condition-dependent MOC variability (hereinafter referred to as "chaotic" variability) of several Sv (1Sv = 106 m3 s−1) in the Atlantic and the Indo-Pacific. In the Atlantic the chaotic MOC variability represents up to 30% of the total variability at the depths where the maximum MOC occurs. In comparison the chaotic MOC variability is only 5–10% in the non-eddying case. The surface forcing being almost identical in the twin experiments suggests that mesoscale ocean eddies are the most likely cause for the increased chaotic MOC variability in the eddying case. The exact formation time of eddies is determined by the initial conditions which are different in the two model passes, and as a consequence the mesoscale eddy field is decorrelated in the twin experiments. In regions where eddy activity is high in the eddy-permitting model, the correlation of sea surface height variability in the twin runs is close to zero. In the non-eddying case in contrast, we find high correlations (0.9 or higher) over most regions. Looking at the sub- and interannual MOC components separately reveals that most of the chaotic MOC variability is found on subannual timescales for the eddy-permitting model. On interannual timescales the amplitude of the chaotic MOC variability is much smaller and the amplitudes are comparable for both the eddy-permitting and non-eddy-permitting model resolutions. Whereas the chaotic MOC variability on interannual timescales only accounts for a small fraction of the total chaotic MOC variability in the eddy-permitting case, it is the main contributor to the chaotic variability in the non-eddying case away from the Equator.

On the shape of sea level anomaly signal on periphery of mesoscale ocean eddies

2017 ◽  
Vol 44 (13) ◽  
pp. 6926-6932 ◽  
Author(s):  
A. Amores ◽  
S. Monserrat ◽  
O. Melnichenko ◽  
N. Maximenko
Keyword(s):  
Sea Level ◽  
Sea Level Anomaly ◽  
Ocean Eddies ◽  
Mesoscale Ocean Eddies

scholarly journals Plankton bloom controlled by horizontal stirring

2009 ◽  
Vol 16 (5) ◽  
pp. 623-630 ◽  
Author(s):  
W. McKiver ◽  
Z. Neufeld ◽  
I. Scheuring
Keyword(s):  
Carrying Capacity ◽  
Single Species ◽  
Transport Processes ◽  
Distributed Model ◽  
Logistic Growth ◽  
Small Scale ◽  
Ocean Eddies ◽  
Mesoscale Ocean Eddies ◽  
Spatially Distributed ◽  
Plankton Bloom

Abstract. Here we show a simple mechanism in which changes in the rate of horizontal stirring by mesoscale ocean eddies can trigger or suppress plankton blooms and can lead to an abrupt change in the average plankton density. We consider a single species phytoplankton model with logistic growth, grazing and a spatially non-uniform carrying capacity. The local dynamics have multiple steady states for some values of the carrying capacity that can lead to localized blooms as fluid moves across the regions with different properties. We show that for this model even small changes in the ratio of biological timescales relative to the flow timescales can greatly enhance or reduce the global plankton productivity. Thus, this may be a possible mechanism in which changes in horizontal mixing can trigger plankton blooms or cause regime shifts in some oceanic regions. Comparison between the spatially distributed model and Lagrangian simulations considering temporal fluctuations along fluid trajectories, demonstrates that small scale transport processes also play an important role in the development of plankton blooms with a significant influence on global biomass.

scholarly journals Imprint of Southern Ocean eddies on chlorophyll

2018 ◽  
Author(s):  
Ivy Frenger ◽  
Matthias Münnich ◽  
Nicolas Gruber
Keyword(s):  
Southern Ocean ◽  
Light Exposure ◽  
Mixed Layer Depth ◽  
Mode Water ◽  
Nutrient Contents ◽  
Ocean Eddies ◽  
Mesoscale Ocean Eddies ◽  
Circumpolar Current ◽  
Pm 10 ◽  
Lateral Advection

Abstract. Although mesoscale ocean eddies are ubiquitous in the Southern Ocean, their spatial and seasonal association with phytoplankton has to date not been quantified in detail. To this end, we identify over 100,000 eddies in the Southern Ocean and determine the associated phytoplankton biomass anomalies using satellite-based chlorophyll-a (Chl) as a proxy. The mean eddy associated Chl anomalies (𝛿Chl) exceed ±10 % over wide regions. The structure of these anomalies is largely zonal, with cyclonic, thermocline lifting, eddies having positive anomalies in the subtropical waters north of the Antarctic Circumpolar Current (ACC) and negative anomalies along the ACC. The pattern is similar, but reversed for anticyclonic, thermocline deepening eddies. The seasonality of 𝛿Chl is weak in subtropical waters, but pronounced along the ACC, featuring a seasonal sign switch. The spatial structure and seasonality of 𝛿Chl can be explained largely by lateral advection, especially eddy-stirring. A prominent exception is the ACC region in winter, where 𝛿Chl is consistent with a modulation of phytoplankton light exposure caused by an eddy-induced modification of the mixed layer depth. The clear impact of eddies on phytoplankton may implicate a downstream effect on Southern Ocean biogeochemical properties, such as mode water nutrient contents.

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