Honing in on bioluminescent milky seas from space

AbstractMilky seas are a rare form of marine bioluminescence where the nocturnal ocean surface produces a widespread, uniform and steady whitish glow. Mariners have compared their appearance to a daylit snowfield that extends to all horizons. Encountered most often in remote waters of the northwest Indian Ocean and the Maritime Continent, milky seas have eluded rigorous scientific inquiry, and thus little is known about their composition, formation mechanism, and role within the marine ecosystem. The Day/Night Band (DNB), a new-generation spaceborne low-light imager, holds potential to detect milky seas, but the capability has yet to be demonstrated. Here, we show initial examples of DNB-detected milky seas based on a multi-year (2012–2021) search. The massive bodies of glowing ocean, sometimes exceeding 100,000 km2 in size, persist for days to weeks, drift within doldrums amidst the prevailing sea surface currents, and align with narrow ranges of sea surface temperature and biomass in a way that suggests water mass isolation. These findings show how spaceborne assets can now help guide research vessels toward active milky seas to learn more about them.

Download Full-text

On the robustness of an eastern boundary upwelling ecosystem exposed to multiple stressors

Scientific Reports ◽

10.1038/s41598-021-81549-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ndague Diogoul ◽

Patrice Brehmer ◽

Hervé Demarcq ◽

Salaheddine El Ayoubi ◽

Abou Thiam ◽

...

Keyword(s):

Multiple Stressors ◽

Marine Ecosystem ◽

Trophic Levels ◽

Sea Surface ◽

Relative Index ◽

Upwelling System ◽

The North ◽

Latitudinal Shift ◽

Large Marine Ecosystem ◽

North And South

AbstractThe resistance of an east border upwelling system was investigated using relative index of marine pelagic biomass estimates under a changing environment spanning 20-years in the strongly exploited southern Canary Current Large marine Ecosystem (sCCLME). We divided the sCCLME in two parts (north and south of Cap Blanc), based on oceanographic regimes. We delineated two size-based groups (“plankton” and “pelagic fish”) corresponding to lower and higher trophic levels, respectively. Over the 20-year period, all spatial remote sensing environmental variables increased significantly, except in the area south of Cap Blanc where sea surface Chlorophyll-a concentrations declined and the upwelling favorable wind was stable. Relative index of marine pelagic abundance was higher in the south area compared to the north area of Cap Blanc. No significant latitudinal shift to the mass center was detected, regardless of trophic level. Relative pelagic abundance did not change, suggesting sCCLME pelagic organisms were able to adapt to changing environmental conditions. Despite strong annual variability and the presence of major stressors (overfishing, climate change), the marine pelagic ressources, mainly fish and plankton remained relatively stable over the two decades, advancing our understanding on the resistance of this east border upwelling system.

Download Full-text

Controls of Caribbean surface hydrology during the mid- to late Holocene: insights from monthly resolved coral records

Climate of the Past ◽

10.5194/cp-9-841-2013 ◽

2013 ◽

Vol 9 (2) ◽

pp. 841-858 ◽

Cited By ~ 15

Author(s):

C. Giry ◽

T. Felis ◽

M. Kölling ◽

W. Wei ◽

G. Lohmann ◽

...

Keyword(s):

Late Holocene ◽

Hydrological Cycle ◽

Summer Precipitation ◽

Caribbean Sea ◽

Sea Surface ◽

Surface Currents ◽

Surface Hydrology ◽

Multidecadal Variability ◽

Southern Caribbean ◽

The Caribbean

Abstract. Several proxy-based and modeling studies have investigated long-term changes in Caribbean climate during the Holocene, however, very little is known on its variability on short timescales. Here we reconstruct seasonality and interannual to multidecadal variability of sea surface hydrology of the southern Caribbean Sea by applying paired coral Sr/Ca and δ18O measurements on fossil annually banded Diploria strigosa corals from Bonaire. This allows for better understanding of seasonal to multidecadal variability of the Caribbean hydrological cycle during the mid- to late Holocene. The monthly resolved coral Δδ18O records are used as a proxy for the oxygen isotopic composition of seawater (δ18Osw) of the southern Caribbean Sea. Consistent with modern day conditions, annual δ18Osw cycles reconstructed from three modern corals reveal that freshwater budget at the study site is influenced by both net precipitation and advection of tropical freshwater brought by wind-driven surface currents. In contrast, the annual δ18Osw cycle reconstructed from a mid-Holocene coral indicates a sharp peak towards more negative values in summer, suggesting intense summer precipitation at 6 ka BP (before present). In line with this, our model simulations indicate that increased seasonality of the hydrological cycle at 6 ka BP results from enhanced precipitation in summertime. On interannual to multidecadal timescales, the systematic positive correlation observed between reconstructed sea surface temperature and salinity suggests that freshwater discharged from the Orinoco and Amazon rivers and transported into the Caribbean by wind-driven surface currents is a critical component influencing sea surface hydrology on these timescales.

Download Full-text

Sacrificial amphiphiles: Eco-friendly chemical herders as oil spill mitigation chemicals

Science Advances ◽

10.1126/sciadv.1400265 ◽

2015 ◽

Vol 1 (5) ◽

pp. e1400265 ◽

Cited By ~ 27

Author(s):

Deeksha Gupta ◽

Bivas Sarker ◽

Keith Thadikaran ◽

Vijay John ◽

Charles Maldarelli ◽

...

Keyword(s):

Crude Oil ◽

Oil Spill ◽

Oil Spills ◽

Cold Water ◽

Marine Ecosystem ◽

Hot Water ◽

Sea Surface ◽

Marine Biota ◽

Polar Group ◽

Branched Chain

Crude oil spills are a major threat to marine biota and the environment. When light crude oil spills on water, it forms a thin layer that is difficult to clean by any methods of oil spill response. Under these circumstances, a special type of amphiphile termed as “chemical herder” is sprayed onto the water surrounding the spilled oil. The amphiphile forms a monomolecular layer on the water surface, reducing the air–sea surface tension and causing the oil slick to retract into a thick mass that can be burnt in situ. The current best-known chemical herders are chemically stable and nonbiodegradable, and hence remain in the marine ecosystem for years. We architect an eco-friendly, sacrificial, and effective green herder derived from the plant-based small-molecule phytol, which is abundant in the marine environment, as an alternative to the current chemical herders. Phytol consists of a regularly branched chain of isoprene units that form the hydrophobe of the amphiphile; the chain is esterified to cationic groups to form the polar group. The ester linkage is proximal to an allyl bond in phytol, which facilitates the hydrolysis of the amphiphile after adsorption to the sea surface into the phytol hydrophobic tail, which along with the unhydrolyzed herder, remains on the surface to maintain herding action, and the cationic group, which dissolves into the water column. Eventual degradation of the phytol tail and dilution of the cation make these sacrificial amphiphiles eco-friendly. The herding behavior of phytol-based amphiphiles is evaluated as a function of time, temperature, and water salinity to examine their versatility under different conditions, ranging from ice-cold water to hot water. The green chemical herder retracted oil slicks by up to ~500, 700, and 2500% at 5°, 20°, and 35°C, respectively, during the first 10 min of the experiment, which is on a par with the current best chemical herders in practice.

Download Full-text

On Capabilities of Tracking Marine Surface Currents Using Artificial Film Slicks

Remote Sensing ◽

10.3390/rs11070840 ◽

2019 ◽

Vol 11 (7) ◽

pp. 840 ◽

Cited By ~ 3

Author(s):

Ivan Kapustin ◽

Olga Shomina ◽

Alexey Ermoshkin ◽

Nikolay Bogatov ◽

Alexander Kupaev ◽

...

Keyword(s):

Water Film ◽

Remote Sensing Data ◽

Sea Surface ◽

Application Of Surfactants ◽

Surface Currents ◽

Band Formation ◽

Suggested Approach ◽

Marine Currents ◽

Sar Imagery ◽

Film Spreading

It is known that films on the sea surface can appear due to ship pollution, river and collector drains, as well as natural biological processes. Marine film slicks can indicate various geophysical processes in the upper layer of the ocean and in the atmosphere. In particular, slick signatures in SAR-imagery of the sea surface at low and moderate wind speeds are often associated with marine currents. Apart from the current itself, other factors such as wind and the physical characteristics of films can significantly influence the dynamics of slick structures. In this paper, a prospective approach aimed at measuring surface currents is developed. The approach is based on the investigation of the geometry of artificial banded slicks formed under the action of marine currents and on the retrieval of the current characteristics from this geometry. The developed approach is applied to quasi stationary slick bands under conditions when the influence of the film spreading effects can be neglected. For the stationary part of the slick band where transition processes of the band formation, e.g., methods of application of surfactants on water, film spreading processes, possible wind transformation etc., become negligible, some empirical relations between the band geometrical characteristics and the characteristics of the surface currents are obtained. The advantage of the approach is a possibility of getting information concerning the spatial structure of marine currents along the entire slick band. The suggested approach can be efficient for remote sensing data verification.

Download Full-text

Challenges for a new generation of marine ecosystem models: Overview of the Advances in Marine Ecosystem Modelling Research (AMEMR) Symposium, 23–26 June 2008, Plymouth UK

Journal of Marine Systems ◽

10.1016/j.jmarsys.2009.12.018 ◽

2010 ◽

Vol 81 (1-2) ◽

pp. 1-3 ◽

Cited By ~ 6

Author(s):

Jerry Blackford ◽

J. Icarus Allen ◽

Thomas R. Anderson ◽

Kenneth A. Rose

Keyword(s):

Marine Ecosystem ◽

Ecosystem Modelling ◽

Ecosystem Models ◽

Marine Ecosystem Models ◽

New Generation

Download Full-text

Large-Scale Environmental Characteristics of MJOs that Strengthen and Weaken over the Maritime Continent

Journal of Climate ◽

10.1175/jcli-d-17-0576.1 ◽

2018 ◽

Vol 31 (14) ◽

pp. 5731-5748 ◽

Cited By ~ 4

Author(s):

Casey D. Burleyson ◽

Samson M. Hagos ◽

Zhe Feng ◽

Brandon W. J. Kerns ◽

Daehyun Kim

Keyword(s):

Seasonal Cycle ◽

Large Scale ◽

Longwave Radiation ◽

Sea Surface ◽

Madden Julian Oscillation ◽

Moist Static Energy ◽

Maritime Continent ◽

New Finding ◽

Field Campaigns ◽

Static Energy

Abstract The characteristics of Madden–Julian oscillation (MJO) events that strengthen and weaken over the Maritime Continent (MC) are examined. The real-time multivariate MJO (RMM) index is used to assess changes in global MJO amplitude over the MC. The MJO weakens at least twice as often as it strengthens over the MC, with weakening MJOs being twice as likely during El Niño compared to La Niña years and the reverse for strengthening events. MJO weakening shows a pronounced seasonal cycle that has not been previously documented. During the Northern Hemisphere (NH) summer and fall the RMM index can strengthen over the MC. MJOs that approach the MC during the NH winter typically weaken according to the RMM index. This seasonal cycle corresponds to whether the MJO crosses the MC primarily north or south of the equator. Because of the seasonal cycle, weakening MJOs are characterized by positive sea surface temperature and moist-static energy anomalies in the Southern Hemisphere (SH) of the MC compared to strengthening events. Analysis of the outgoing longwave radiation (OLR) MJO index (OMI) shows that MJO precipitation weakens when it crosses the MC along the equator. A possible explanation of this based on previous results is that the MJO encounters more landmasses and taller mountains when crossing along the equator or in the SH. The new finding of a seasonal cycle in MJO weakening over the MC highlights the importance of sampling MJOs throughout the year in future field campaigns designed to study MJO–MC interactions.

Download Full-text

A Synergetic Approach for the Space-Based Sea Surface Currents Retrieval in the Mediterranean Sea

Remote Sensing ◽

10.3390/rs11111285 ◽

2019 ◽

Vol 11 (11) ◽

pp. 1285 ◽

Cited By ~ 4

Author(s):

Daniele Ciani ◽

Marie-Hélène Rio ◽

Milena Menna ◽

Rosalia Santoleri

Keyword(s):

Numerical Model ◽

Mediterranean Sea ◽

Mediterranean Area ◽

Hf Radar ◽

Sea Surface ◽

Reconstruction Method ◽

Surface Currents ◽

Basin Scale ◽

The Mediterranean ◽

Sicily Channel

We present a method for the remote retrieval of the sea surface currents in the Mediterranean Sea. Combining the altimeter-derived currents with sea-surface temperature information, we created daily, gap-free high resolution maps of sea surface currents for the period 2012–2016. The quality of the new multi-sensor currents has been assessed through comparisons to other surface-currents estimates, as the ones obtained from drifting buoys trajectories (at the basin scale), or HF-Radar platforms and ocean numerical model outputs in the Malta–Sicily Channel. The study yielded that our synergetic approach can improve the present-day derivation of the surface currents in the Mediterranean area up to 30% locally, with better performances for the the meridional component of the motion and in the western section of the basin. The proposed reconstruction method also showed satisfying performances in the retrieval of the ageostrophic circulation in the Sicily Channel. In this area, assuming the High Frequency Radar-derived currents as reference, the merged multi-sensor currents exhibited improvements with respect to the altimeter estimates and numerical model outputs, mainly due to their enhanced spatial and temporal resolution.

Download Full-text

Validation of HF radar sea surface currents in the Malta-Sicily Channel

Remote Sensing of Environment ◽

10.1016/j.rse.2019.02.026 ◽

2019 ◽

Vol 225 ◽

pp. 65-76 ◽

Cited By ~ 7

Author(s):

Fulvio Capodici ◽

Simone Cosoli ◽

Giuseppe Ciraolo ◽

Carmelo Nasello ◽

Antonino Maltese ◽

...

Keyword(s):

Hf Radar ◽

Sea Surface ◽

Surface Currents ◽

Sicily Channel

Download Full-text

Wind currents, tidal streams and plankton off the Northumberland coast

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400006950 ◽

1959 ◽

Vol 38 (3) ◽

pp. 529-541 ◽

Cited By ~ 3

Author(s):

Frank Evans

Keyword(s):

Water Flow ◽

Surface Region ◽

Sea Surface ◽

Surface Currents ◽

Total Water ◽

Tidal Streams ◽

Wind Currents

Investigations of the water movements off the southern Northumberland coast have until now been confined to the surface region. While important for navigational and similar purposes such investigations can give us no more than an indication of the total water flow along the coast nor can they elucidate the effects of currents on planktonic organisms which spend part or all of their existence away from the surface. It is for the latter reason that the series of investigations of sea surface currents made aboard the R.V. ‘Alexander Meek’ in 1956–7 (Evans, 1957) has now been supplemented by further series at two deeper levels.

Download Full-text