El Niño rides again

NASA Astrophysics Data System (ADS)

Friebele, Elaine

Another weather-disrupting El Niño may be brewing in the Pacific Ocean, according to ocean measurements taken by NASA instruments on two orbiting satellites. Sea-surface height measurements taken by the radar altimeter on board the joint U.S.-French TOPEX/Poseidon satellite and wind data collected by the NASA scatterometer on Japan's Advanced Earth Observing Satellite (ADEOS) have been used together for the first time to predict changing weather conditions in the tropical Pacific Ocean.El Niño occurs when steady westward blowing trade winds weaken and reverse direction, moving the mass of warm water near Australia eastward to the coast of South America. The displacement of the warm water mass alters the atmospheric jet stream and weather patterns around the world. The TOPEX/Poseidon satellite uses an altimeter to bounce radar signals off the ocean's surface to make precise measurements of the distance between the satellite and sea surface. Researchers then map the barely perceptible hills and valleys of the sea surface by combining these data with measurements pinpointing the satellite's exact location in space.

Four-dimensional variational Ocean ReAnalysis for the Western North Pacific over 30 years (FORA-WNP30)

NASA Astrophysics Data System (ADS)

Hirose, N.; Takatsuki, Y.; Usui, N.; Wakamatsu, T.; Tanaka, Y.; Toyoda, T.; Nishikawa, S.; Fujii, Y.; Igarashi, H.; Nishikawa, H.; Ishikawa, Y.; Kuragano, T.; Kamachi, M.

2016-12-01

An ocean reanalysis, FORA-WNP30, was produced by the collaborative work of Meteorological Research Institute, Japan Meteorological Agency (JMA/MRI) and Japan Agency for Marine-Earth Science and Technology (JAMSTEC). A state-of-the-art 4-dimensional variational ocean data assimilation system, MOVE-4DVAR (Usui et al., 2015) was used. The calculation for the reanalysis, with the horizontal resolution of 0.1 degree (about 10 km) and the period between 1 January 1982 and 31 December 2014, was carried out on the Earth Simulator with the support of JAMSTEC. The model forcing is derived from the JRA-55 atmospheric reanalysis product. In-situ temperature and salinity profiles above 1500m-depth, satellite-based sea surface temperature (SST) and sea surface height (SSH) data are assimilated in FORA-WNP30.Using the current observations obtained by the Acoustic Doppler Current Profiler (ADCP) installed in two JMA research vessels, we validate the current (velocity) field in FORA-WNP30 and MOVE-3DVAR system, the latter of which is an operational ocean data assimilation system in JMA. The ADCP current data are independent because they are not assimilated in both systems. The current fields at 100-m depth during 2001-2012, in both of FORA-WNP30 and MOVE-3DVAR show high correlation with ADCP observation in the south of Japan, the East China Sea and the Kuroshio extension region, and relatively low correlation in the Japan Sea and the Oyashio region. The correlation coefficients of current speed for FORA-WNP30 are higher than those for MOVE-3DVAR in all regions.FORA-WNP30 successfully reproduces not only the major ocean current such as the Kuroshio and Oyashio, but also the associated meso-scale phenomena such as eddies, fronts, and meanders. In addition, it replicates the Kuroshio large meander events and the strong intrusion event of the Oyashio in 1980s, in spite of no satellite altimeter data for this period. Therefore, FORA-WNP30 is a valuable dataset for use in a variety of oceanographic process study and related fields such as climate study, meteorology, and fisheries.

GPS Ocean Reflection Experiment (GORE) Wind Explorer (WindEx) Instrument Design and Development

NASA Astrophysics Data System (ADS)

Ganoe, G.

2004-12-01

This paper describes the design and development of the WindEx instrument, and the technology implemented by it. The important design trades will be covered along with the justification for the options selected. An evaluation of the operation of the instrument, and plans for continued development and enhancements will also be given. The WindEx instrument consists of a processor that receives data from an included GPS Surface reflection receiver, and computes ocean surface wind speeds in real time utilizing an algorithm developed at LaRC by Dr. Stephen J. Katzberg. The WindEx performs a windspeed server function as well as acting as a repository for the client moving map applications, and providing a web page with instructions on the installation and use of the WindEx system. The server receives the GPS reflection data produced by the receiver, performs wind speed processing, then makes the wind speed data available as a moving map display to requesting client processors on the aircraft network. The client processors are existing systems used by the research personnel onboard. They can be configured to be WINDEX clients by downloading the Java client application from the WINDEX server. The client application provides a graphical display of a moving map that shows the aircraft position along with the position of the reflection point from the surface of the ocean where the wind speed is being estimated, and any coastlines within the field of view. Information associated with the reflection point includes the estimated wind speed, and a confidence factor that gives the researcher an idea about the reliability of the wind speed measurement. The instrument has been installed on one of NOAA's Hurricane Hunters, a Gulfstream IV, whose nickname is "Gonzo". Based at MacDill AFB, Florida, "Gonzo" flies around the periphery of the storm deploying GPS-based dropsondes which measure local winds. The dropsondes are the "gold-standard" for determining surface winds, but can only be deployed sparingly. The GPS WindEx system allows for a continuous map between dropsonde releases as well as monitoring the ocean surface for suspicious areas. The GPS technique is insensitive to clouds or rain and can give information concerning surface conditions not available to the flight crew.

Interferometric synthetic aperture radar imagery of the Gulf Stream

NASA Technical Reports Server (NTRS)

Ainsworth, T. L.; Cannella, M. E.; Jansen, R. W.; Chubb, S. R.; Carande, R. E.; Foley, E. W.; Goldstein, R. M.; Valenzuela, G. R.

1993-01-01

The advent of interferometric synthetic aperture radar (INSAR) imagery brought to the ocean remote sensing field techniques used in radio astronomy. Whilst details of the interferometry differ between the two fields, the basic idea is the same: Use the phase information arising from positional differences of the radar receivers and/or transmitters to probe remote structures. The interferometric image is formed from two complex synthetic aperture radar (SAR) images. These two images are of the same area but separated in time. Typically the time between these images is very short -- approximately 50 msec for the L-band AIRSAR (Airborne SAR). During this short period the radar scatterers on the ocean surface do not have time to significantly decorrelate. Hence the two SAR images will have the same amplitude, since both obtain the radar backscatter from essentially the same object. Although the ocean surface structure does not significantly decorrelate in 50 msec, surface features do have time to move. It is precisely the translation of scattering features across the ocean surface which gives rise to phase differences between the two SAR images. This phase difference is directly proportional to the range velocity of surface scatterers. The constant of proportionality is dependent upon the interferometric mode of operation.

Global nutrient transport in a world of giants

PubMed Central

Doughty, Christopher E.; Roman, Joe; Faurby, Søren; Wolf, Adam; Haque, Alifa; Bakker, Elisabeth S.; Malhi, Yadvinder; Dunning, John B.; Svenning, Jens-Christian

2016-01-01

The past was a world of giants, with abundant whales in the sea and large animals roaming the land. However, that world came to an end following massive late-Quaternary megafauna extinctions on land and widespread population reductions in great whale populations over the past few centuries. These losses are likely to have had important consequences for broad-scale nutrient cycling, because recent literature suggests that large animals disproportionately drive nutrient movement. We estimate that the capacity of animals to move nutrients away from concentration patches has decreased to about 8% of the preextinction value on land and about 5% of historic values in oceans. For phosphorus (P), a key nutrient, upward movement in the ocean by marine mammals is about 23% of its former capacity (previously about 340 million kg of P per year). Movements by seabirds and anadromous fish provide important transfer of nutrients from the sea to land, totalling ∼150 million kg of P per year globally in the past, a transfer that has declined to less than 4% of this value as a result of the decimation of seabird colonies and anadromous fish populations. We propose that in the past, marine mammals, seabirds, anadromous fish, and terrestrial animals likely formed an interlinked system recycling nutrients from the ocean depths to the continental interiors, with marine mammals moving nutrients from the deep sea to surface waters, seabirds and anadromous fish moving nutrients from the ocean to land, and large animals moving nutrients away from hotspots into the continental interior. PMID:26504209

Global nutrient transport in a world of giants.

PubMed

Doughty, Christopher E; Roman, Joe; Faurby, Søren; Wolf, Adam; Haque, Alifa; Bakker, Elisabeth S; Malhi, Yadvinder; Dunning, John B; Svenning, Jens-Christian

2016-01-26

The past was a world of giants, with abundant whales in the sea and large animals roaming the land. However, that world came to an end following massive late-Quaternary megafauna extinctions on land and widespread population reductions in great whale populations over the past few centuries. These losses are likely to have had important consequences for broad-scale nutrient cycling, because recent literature suggests that large animals disproportionately drive nutrient movement. We estimate that the capacity of animals to move nutrients away from concentration patches has decreased to about 8% of the preextinction value on land and about 5% of historic values in oceans. For phosphorus (P), a key nutrient, upward movement in the ocean by marine mammals is about 23% of its former capacity (previously about 340 million kg of P per year). Movements by seabirds and anadromous fish provide important transfer of nutrients from the sea to land, totalling ∼150 million kg of P per year globally in the past, a transfer that has declined to less than 4% of this value as a result of the decimation of seabird colonies and anadromous fish populations. We propose that in the past, marine mammals, seabirds, anadromous fish, and terrestrial animals likely formed an interlinked system recycling nutrients from the ocean depths to the continental interiors, with marine mammals moving nutrients from the deep sea to surface waters, seabirds and anadromous fish moving nutrients from the ocean to land, and large animals moving nutrients away from hotspots into the continental interior.

KSC-08pd1672

NASA Image and Video Library

2008-06-01

VANDENBERG AIR FORCE BASE, Calif. – An overhead crane is used to move the covered Ocean Surface Topography Mission, or OSTM/Jason 2, spacecraft onto a transporter for the trip to the launch pad. The launch of the OSTM/Jason 2 aboard a Delta II rocket is scheduled for Friday, June 20, from Vandenberg Air Force Base in California. The launch window extends from 12:46 a.m. to 12:55 a.m. PDT. The satellite will be placed in an 830-mile-high orbit at an inclination of 66 degrees after separating from the Delta II 55 minutes after liftoff. The five primary science instruments of the Ocean Surface Topography Mission aboard the Jason 2 spacecraft are dedicated to measuring ocean surface height. These measurements will be used to evaluate and forecast climate changes and improve weather forecasting. The results also are expected to help forecasters better predict hurricane intensity. Photo credit: NASA/Dan Liberotti

The Impact of Sea Surface Temperature on Organized Convective Storms Crossing over Coastlines

NASA Astrophysics Data System (ADS)

Lombardo, K.

2016-02-01

As organized coastal convective storms develop over land and move over the coastal ocean, their storm-scale structures, intensity, and associated weather threats evolve. This study aims to quantify the impact of sea surface temperature on the fundamental mechanisms controlling the evolution of coastal quasi-linear convective systems (QLCSs) as they move offshore. Results from this work will contribute to the improved predictability of these coastal, potentially severe warm season storms. The current work systematically studies the interaction between QLCSs and marine atmospheric boundary layers (MABLs) associated with the coastal ocean in an idealized numerical framework. The initial simulations are run in 2-dimensions, with a 250 m horizontal resolution and a vertical resolution ranging from 100 m in the lowest 3000 m stretched to 250 m at the top of the 20 km domain. To create a numerical environment representative of a coastal region, the western half of the 800 km domain is configured to represent a land surface, while the eastern half represents a water surface. A series of sensitivity experiments are conducted to explore the influence of sea surface temperature and the overlying MABL on coastal QLCSs. Sea surface temperature values are selected to represent values observed within the Mid-Atlantic Bight coastal waters, including 5oC (min SST - January), 14oC (early summer), and 23oC (late summer). The numerical MABL is allowed to develop through surface heat fluxes. Preliminary simulations indicate that SST influences storm structure, with the stratiform precipitation shield becoming progressively wider as SST increases. SST also impacts propagation speed; once the storms are over the water, the early and late summer QLCSs move more quickly than the min SST storm. The physical mechanisms contributing to these and other differences will be discussed.

Boundary Layer Flow Over a Moving Wavy Surface

NASA Astrophysics Data System (ADS)

Hendin, Gali; Toledo, Yaron

2016-04-01

Boundary Layer Flow Over a Moving Wavy Surface Gali Hendin(1), Yaron Toledo(1) January 13, 2016 (1)School of Mechanical Engineering, Tel-Aviv University, Israel Understanding the boundary layer flow over surface gravity waves is of great importance as various atmosphere-ocean processes are essentially coupled through these waves. Nevertheless, there are still significant gaps in our understanding of this complex flow behaviour. The present work investigates the fundamentals of the boundary layer air flow over progressive, small-amplitude waves. It aims to extend the well-known Blasius solution for a boundary layer over a flat plate to one over a moving wavy surface. The current analysis pro- claims the importance of the small curvature and the time-dependency as second order effects, with a meaningful impact on the similarity pattern in the first order. The air flow over the ocean surface is modelled using an outer, inviscid half-infinite flow, overlaying the viscous boundary layer above the wavy surface. The assumption of a uniform flow in the outer layer, used in former studies, is now replaced with a precise analytical solution of the potential flow over a moving wavy surface with a known celerity, wavelength and amplitude. This results in a conceptual change from former models as it shows that the pressure variations within the boundary layer cannot be neglected. In the boundary layer, time-dependent Navier-Stokes equations are formulated in a curvilinear, orthogonal coordinate system. The formulation is done in an elaborate way that presents additional, formerly neglected first-order effects, resulting from the time-varying coordinate system. The suggested time-dependent curvilinear orthogonal coordinate system introduces a platform that can also support the formulation of turbulent problems for any surface shape. In order to produce a self-similar Blasius-type solution, a small wave-steepness is assumed and a perturbation method is applied. Consequently, a novel self-similar solution is obtained from the first order set of equations. A second order solution is also obtained, stressing the role of small curvature on the boundary layer flow. The proposed model and solution for the boundary layer problem overlaying a moving wavy surface can also be used as a base flow for stability problems that can develop in a boundary layer, including phases of transitional states.

Comparison of MTI Satellite-Derived Surface Water Temperatures and In-Situ Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurzeja, R.

2001-07-26

Temperatures of the water surface of a cold, mid-latitude lake and the tropical Pacific Ocean were determined from MTI images and from in situ concurrent measurements. In situ measurements were obtained at the time of the MTI image with a floating, anchored platform, which measured the surface and bulk water temperatures and relevant meteorological variables, and also from a boat moving across the target area. Atmospheric profiles were obtained from concurrent radiosonde soundings. Radiances at the satellite were calculated with the Modtran radiative transfer model. The MTI infrared radiances were within 1 percent of the calculated values at the Pacificmore » Ocean site but were 1-2 percent different over the mid-latitude lake.« less

Meteorological Research Institute multivariate ocean variational estimation (MOVE) system: Some early results

NASA Astrophysics Data System (ADS)

Usui, Norihisa; Ishizaki, Shiro; Fujii, Yosuke; Tsujino, Hiroyuki; Yasuda, Tamaki; Kamachi, Masafumi

The Meteorological Research Institute multivariate ocean variational estimation (MOVE) System has been developed as the next-generation ocean data assimilation system in Japan Meteorological Agency. A multivariate three-dimensional variational (3DVAR) analysis scheme with vertical coupled temperature salinity empirical orthogonal function modes is adopted. The MOVE system has two varieties, the global (MOVE-G) and North Pacific (MOVE-NP) systems. The equatorial Pacific and western North Pacific are analyzed with assimilation experiments using MOVE-G and -NP, respectively. In each system, the salinity and velocity fields are well reproduced, even in cases without salinity data. Changes in surface and subsurface zonal currents during the 1997/98 El Niño event are captured well, and their transports are reasonably consistent with in situ observations. For example, the eastward transport in the upper layer around the equator has 70 Sv in spring 1997 and weakens in spring 1998. With MOVE-NP, the Kuroshio transport has 25 Sv in the East China Sea, and 40 Sv crossing the ASUKA (Affiliated Surveys of the Kuroshio off Cape Ashizuri) line south of Japan. The variations in the Kuroshio transports crossing the ASUKA line agree well with observations. The Ryukyu Current System has a transport ranging from 6 Sv east of Taiwan to 17 Sv east of Amami. The Oyashio transport crossing the OICE (Oyashio Intensive observation line off Cape Erimo) line south of Hokkaido has 14 Sv southwestward (near shore) and 11 Sv northeastward (offshore). In the Kuroshio Oyashio transition area east of Japan, the eastward transport has 41 Sv (32 36°N) and 12 Sv (36 39°N) crossing the 145°E line.

Depth of origin of ocean-circulation-induced magnetic signals

NASA Astrophysics Data System (ADS)

Irrgang, Christopher; Saynisch-Wagner, Jan; Thomas, Maik

2018-01-01

As the world ocean moves through the ambient geomagnetic core field, electric currents are generated in the entire ocean basin. These oceanic electric currents induce weak magnetic signals that are principally observable outside of the ocean and allow inferences about large-scale oceanic transports of water, heat, and salinity. The ocean-induced magnetic field is an integral quantity and, to first order, it is proportional to depth-integrated and conductivity-weighted ocean currents. However, the specific contribution of oceanic transports at different depths to the motional induction process remains unclear and is examined in this study. We show that large-scale motional induction due to the general ocean circulation is dominantly generated by ocean currents in the upper 2000 m of the ocean basin. In particular, our findings allow relating regional patterns of the oceanic magnetic field to corresponding oceanic transports at different depths. Ocean currents below 3000 m, in contrast, only contribute a small fraction to the ocean-induced magnetic signal strength with values up to 0.2 nT at sea surface and less than 0.1 nT at the Swarm satellite altitude. Thereby, potential satellite observations of ocean-circulation-induced magnetic signals are found to be likely insensitive to deep ocean currents. Furthermore, it is shown that annual temporal variations of the ocean-induced magnetic field in the region of the Antarctic Circumpolar Current contain information about sub-surface ocean currents below 1000 m with intra-annual periods. Specifically, ocean currents with sub-monthly periods dominate the annual temporal variability of the ocean-induced magnetic field.

Open Ocean Internal Waves, South China Sea

NASA Technical Reports Server (NTRS)

1989-01-01

These open ocean internal waves were seen in the south China Sea (19.5N, 114.5E). These sets of internal waves most likely coincide with tidal periods about 12 hours apart. The wave length (distance from crest to crest) varies between 1.5 and 5.0 miles and the crest lengths stretch across and beyond this photo for over 75 miles. At lower right, the surface waves are moving at a 30% angle to the internal waves, with parallel low level clouds.

Ocean dynamics during the passage of Xynthia storm recorded by GPS

NASA Astrophysics Data System (ADS)

Nicolas, Joëlle; Ferenc, Marcell; Li, Zhao; van Dam, Tonie; Polidori, Laurent

2014-05-01

When computing the effect of atmospheric loading on geodetic coordinates, we must assign the response of the ocean to pressure loading. A pure inverted barometer and a solid Earth ocean response to pressure loading define the extremes of the response. At periods longer than a few days, the inverted barometer response is sufficient (Wunsch and Stammer, 1997). However, how does the ocean respond to fast moving storms? In this study we investigate the effect of a violent storm that progressed over Western Europe between the 27th of February and the 1st of March 2010 on sub-daily vertical GPS (Global Positioning System) position time series of the French GNSS permanent network (RGP). Xynthia was a huge low-pressure system (pressure drop of 40 mbar and a storm surge of 1.4 m (at La Rochelle tide gauge)) that crossed France from the southwest to the northeast over the course of about 20 hours. We study the different behaviour of the coastal and inland sites based on the comparison of the estimated 6-hourly stand-alone GPS position time series (GINS-PC software) with the local pressure and the predicted atmospheric pressure loading time series derived from the high resolution Modern-Era Retrospective Analysis for Research and Applications (NASA MERRA) and also the European Centre for Medium-Range Weather Forecasts (ECMWF) global dataset. We model the predicted displacements using the inverse barometer (IB) and the non-IB ocean response cases as endpoints. Predicted loading effects due to the atmospheric pressure and IB ocean reach up to 1.0, 1.3 and 13.7 mm for the east, north and up components, respectively. Then we attempt to use the GPS vertical surface displacements, the surface pressure, and tide gauge data (SONEL) to identify the true ocean dynamics on the continental shelf during the passage of this fast moving system. Keywords: GPS, GINS-PC, Xynthia, ocean dynamics, atmospheric pressure loading, deformation

Two-frequency /Delta k/ microwave scatterometer measurements of ocean wave spectra from an aircraft

NASA Technical Reports Server (NTRS)

Johnson, J. W.; Jones, W. L.; Weissman, D. E.

1981-01-01

A technique for remotely sensing the large-scale gravity wave spectrum on the ocean surface using a two frequency (Delta k) microwave scatterometer has been demonstrated from stationary platforms and proposed from moving platforms. This measurement takes advantage of Bragg type resonance matching between the electromagnetic wavelength at the difference frequency and the length of the large-scale surface waves. A prominent resonance appears in the cross product power spectral density (PSD) of the two backscattered signals. Ku-Band aircraft scatterometer measurements were conducted by NASA in the North Sea during the 1979 Maritime Remote Sensing (MARSEN) experiment. Typical examples of cross product PSD's computed from the MARSEN data are presented. They demonstrate strong resonances whose frequency and bandwidth agree with the surface characteristics and the theory. Directional modulation spectra of the surface reflectivity are compared to the gravity wave spectrum derived from surface truth measurements.

Emerging role of Indian ocean on Indian northeast monsoon

NASA Astrophysics Data System (ADS)

Yadav, Ramesh Kumar

2013-07-01

This study examines the emerging role of Indian Ocean sea surface temperature (SST) on the inter-annual variability (IAV) of Indian north-east monsoon rainfall (NEMR). The IAV of NEMR is associated with the warm SST anomaly over east Bay-of-Bengal (BoB) (88.5oE-98.5oE; 8.5oN-15.5oN) and cool SST anomaly over east equatorial Indian Ocean (80.5oE-103.5oE; 6.5oS-3.5oN). The gradient of SST between these boxes (i.e. northern box minus southern box) shows strong and robust association with the Indian NEMR variability in the recent decades. For establishing the teleconnections, SST, mean sea level pressure, North Indian Ocean tropical storm track, and circulation data have been used. The study reveals that during the positive SST gradient years, the inter-tropical convergence zone (ITCZ) shifts northwards over the East Indian Ocean. The tropical depressions, storms and cyclones formed in the North Indian Ocean moves more zonally and strike the southern peninsular India and hence excess NEMR. While, during the negative SST gradient years, the ITCZ shifts southwards over the Indian Ocean. The tropical depressions, storms and cyclones formed in the North Indian Ocean moves more northwestward direction and after crossing 15oN latitude re-curve to north-east direction towards head BoB and misses southern peninsular India and hence, deficient NEMR.

Body and Surface Wave Modeling of Observed Seismic Events

DTIC Science & Technology

1980-09-01

with a deep root of the Sierra Nevada mountains or crustal transitions along the continental oceanic boundaries. These paths can be identified by...suggests that the Adriatic Sea is a separate microplate , the Apulian plate which may move independently of the larger plates. Except for the existence of

Backscattering from targets residing in caustics resulting from ocean boundary interactions

NASA Astrophysics Data System (ADS)

Dzikowicz, Benjamin R.; Marston, Philip L.

2005-04-01

Detection of targets by backscatter in shallow water can be enhanced by interactions with ocean boundaries. A laboratory experiment is performed where a spherical target passes through an Airy caustic formed by a curved surface. When the target resides in the insonified region of the caustic there are two sets of multi-path rays: two pairs reflecting once off the surface (either to or from the target), and three reflecting twice off the surface (to and from the target). When a target moves across the caustic the singly reflected rays merge, as do the doubly reflected. With a longer tone burst the rays in each set overlap and the backscatter is greatly enhanced as the target moves into the insonified region. For a point target the singly reflected backscatter scales as an Airy function [B. R. Dzikowicz and P. L. Marston, J. Acoust. Soc. Am. 116, 2751-2757 (2004)], and the doubly reflected as the square of an Airy function. For a finite target the doubly reflected backscatter unfolds into a hyperbolic umbilic function. The arguments of the Airy and Hyperbolic Umbilic functions are calculated using the relative echo times of transient pulses. [Work supported by ONR.

Spontaneous Wave Generation from Submesoscale Fronts and Filaments

NASA Astrophysics Data System (ADS)

Shakespeare, C. J.; Hogg, A.

2016-02-01

Submesoscale features such as eddies, fronts, jets and filaments can be significant sources of spontaneous wave generation at the ocean surface. Unlike near-inertial waves forced by winds, these spontaneous waves are typically of higher frequency and can propagate through the thermocline, whereupon they break and drive mixing in the ocean interior. Here we investigate the spontaneous generation, propagation and subsequent breaking of these waves using a combination of theory and submesoscale resolving numerical models. The mechanism of generation is nearly identical to that of lee waves where flow is deflected over a rigid obstacle on the sea floor. Here, very sharp fronts and filaments of order 100m width moving in the submesoscale surface flow generate "surface lee waves" by presenting an obstacle to the surrounding stratified fluid. Using our numerical model we quantify the net downward wave energy flux from the surface, and where it is dissipated in the water column. Our results suggest an alternative to the classical paradigm where the energy associated with mixing in the ocean interior is sourced from bottom-generated lee waves.

Subduction hinge migration: The backwards component of plate tectonics

NASA Astrophysics Data System (ADS)

Stegman, D.; Freeman, J.; Schellart, W.; Moresi, L.; May, D.

2005-12-01

There are approximately 50 distinct segments of subduction zones in the world, of which 40% have oceanic lithosphere subducting under oceanic lithosphere. All of these ocean-ocean systems are currently experiencing hinge-rollback, with the exception of 2 (Mariana and Kermadec). In hinge-rollback, the surface trace of the suduction zone (trench) is moving in the opposite direction as the plate is moving (i.e. backwards). Coincidentally, the fastest moving plate boundary in the world is actually the Tonga trench at an estimated 17 cm/yr (backwards). Although this quite important process was recognized soon after the birth of plate tectonic theory (Elsasser, 1971), it has received only a limited amount of attention (Garfunkel, 1986; Kincaid and Olson, 1987) until recently. Laboratory models have shown that having a three dimensional experiment is essential in order to build a correct understanding of subduction. We have developed a numerical model with the neccessary 3-D geometry capable of investigating some fundamental questions of plate tectonics: How does hinge-rollback feedback into surface tectonics and mantle flow? What can we learn about the forces that drive plate tectonics by studying hinge-rollback? We will present a quantatitive analysis of the effect of the lateral width of subduction zones, the key aspect to understanding the nature of hinge-rollback. Additionally, particular emphasis has been put on gaining intuition through the use of movies (a 3-D rendering of the numerical models), illustrating the time evolution of slab interactions with the lower mantle as seen in such fields as velocity magnitude, strain rate, viscosity, as well as the toroidal and poloidal components of induced flow. This investigation is well-suited to developing direct comparisons with geological and geophysical observations such as geodetically determined hinge retreat rates, geochemical and petrological observations of arc volcanics and back-arc ridge basalts, timing and distribution of metamorphic core complexes in backarc basins under extension, paleostress observables such surface movements and block rotations, observations of seismic anistropy determined by shear wave splitting, and the emerging studies of regional tomographic models of seismic anistropy.

Oceanic circulation models help to predict global biogeography of pelagic yellow-bellied sea snake

PubMed Central

Cotté, Cédric; Bailleul, Frédéric; Lalire, Maxime; Gaspar, Philippe

2016-01-01

It is well recognized that most marine vertebrates, and especially tetrapods, precisely orient and actively move in apparently homogeneous oceanic environments. Here, we investigate the presumptive role of oceanic currents in biogeographic patterns observed in a secondarily marine tetrapod, the yellow-bellied sea snake (Hydrophis [Pelamis] platurus). State-of-the-art world ocean circulation models show how H. platurus, the only pelagic species of sea snake, can potentially exploit oceanic currents to disperse and maintain population mixing between localities that spread over two-thirds of the Earth's circumference. The very close association of these snakes with surface currents seems to provide a highly efficient dispersal mechanism that allowed this species to range extensively and relatively quickly well beyond the central Indo-Pacific area, the centre of origin, abundance and diversity of sea snakes. Our results further suggest that the pan-oceanic population of this species must be extraordinarily large. PMID:27555651

Effect of a sheared flow on iceberg motion and melting

NASA Astrophysics Data System (ADS)

FitzMaurice, A.; Straneo, F.; Cenedese, C.; Andres, M.

2016-12-01

Icebergs account for approximately half the freshwater flux into the ocean from the Greenland and Antarctic ice sheets and play a major role in the distribution of meltwater into the ocean. Global climate models distribute this freshwater by parameterizing iceberg motion and melt, but these parameterizations are presently informed by limited observations. Here we present a record of speed and draft for 90 icebergs from Sermilik Fjord, southeastern Greenland, collected in conjunction with wind and ocean velocity data over an 8 month period. It is shown that icebergs subject to strongly sheared flows predominantly move with the vertical average of the ocean currents. If, as typical in iceberg parameterizations, only the surface ocean velocity is taken into account, iceberg speed and basal melt may have errors in excess of 60%. These results emphasize the need for parameterizations to consider ocean properties over the entire iceberg draft.

The Phenomenom of Ocean Acidification

NASA Astrophysics Data System (ADS)

Weiss, S.

2017-12-01

The earth is 70% and is protected by its atmosphere. The atmosphere is made up of several layers. The sunlight penetrates through the atmosphere and warms the earth surface. The earth's surface then in turn emits invisible infrared radiation back. As this radiation moves back up each layer absorbs some of it. Each layer then sends some of this energy back to earth again. When the layer becomes so thin the energy then escapes back into space. When we are adding more carbon dioxide to these layers we are causing the layers to absorb more of the energy and the radiation. This in turn causes the layers to become warmer since fewer radiation moves up through the layers and this energy bounces back to earth increasing the temperatures. The entire planet is taking on more of this energy and hence the temperatures are rising. The ocean plays a big rule in this change. It has prevented some of the CO2 from entering the earth's atmosphere. Oceans absorb about one third of the anthropogenic CO2 causing the phenomenon of ocean acidification and this comes at a huge cost to our marine environments. The CO2 is absorbed on the surface and then transferred into the deeper waters. Which causes it to be stuck for centuries before making its way back into the atmosphere. As the CO2 dissolves in seawater it causes the PH to lower. With a lowered PH water becomes more acidic. The Hydrogen ions decrease and become less active. With this process carbonic acid is formed. The ocean now is more acidic then it has ever been in the past 650,000 years. The increase in acidic levels has caused our marine life to adjust. Acidosis caused by the increase of carbonic acid in the body fluids means a lower pH in the blood. This changes is just the start to many health issues for these organism's.

Tilted geostrophic convection in icy world oceans caused by the horizontal component of the planetary rotation vector

NASA Astrophysics Data System (ADS)

Goodman, J. C.

2012-12-01

The Coriolis force provides dominant control over the motion of atmospheres and oceans, both on Earth and on many other worlds. At any point on a planet's surface, the planetary rotation vector has both a vertical component and a horizontal (north-south) component. We typically ignore the horizontal component, which is justified if vertical motions are hydrostatic and the fluid is relatively shallow. Neither of these conditions is true for hydrothermal convection within the thick ocean layers of Europa and other icy worlds. Using the MITGCM ocean model, we explore the behavior of buoyant hydrothermal plumes in a deep unstratified ocean, including both components of the planetary rotation vector. We find that warm water does not rise vertically: instead, it spirals along the axis of planetary rotation. Eddies form which are tilted with respect to the local vertical, but parallel to the rotation axis: turbulent exchange of heat between these canted eddies carries the warm water toward the surface. This is not an entirely new idea: however, the implications for icy worlds have not been previously discussed. We observe that when these tilted plumes heat the ice layer above the ocean, the heating "footprint" of these tilted plumes will be more circular near the pole, more ellipsoidal in the tropics. If surface features of the ice crust were created by plume heating, their shapes ought to show consistent latitude trends. Also, we observe that if warm fluid were totally constrained to move along the planetary rotation axis, geothermal heat generated in the icy world's interior could never reach the ice crust near the equator. (For Europa, the "forbidden zone" could extend as far as +/- 20-25° latitude.) In practice, we find that turbulent eddies do allow heat to move perpendicular to the rotation vector, so the "forbidden zone" is not a tight constraint; still, it may affect the overall heating pattern of icy world crusts. Snapshot of ascent of buoyant hydrothermal plume in Europa's ocean (Seafloor heat source = 4 GW; ocean depth = 100 km; rotation period = 3.55 days; latitude = 30° N). Left: elevation section through plume. Right: 3-d isosurface of constant temperature (1 microkelvin above ambient). Note alignment of geostrophic eddies along angular rotation axis.

Crustal control of dissipative ocean tides in Enceladus and other icy moons

NASA Astrophysics Data System (ADS)

Beuthe, Mikael

2016-12-01

Could tidal dissipation within Enceladus' subsurface ocean account for the observed heat flow? Earthlike models of dynamical tides give no definitive answer because they neglect the influence of the crust. I propose here the first model of dissipative tides in a subsurface ocean, by combining the Laplace Tidal Equations with the membrane approach. For the first time, it is possible to compute tidal dissipation rates within the crust, ocean, and mantle in one go. I show that oceanic dissipation is strongly reduced by the crustal constraint, and thus contributes little to Enceladus' present heat budget. Tidal resonances could have played a role in a forming or freezing ocean less than 100 m deep. The model is general: it applies to all icy satellites with a thin crust and a shallow ocean. Scaling rules relate the resonances and dissipation rate of a subsurface ocean to the ones of a surface ocean. If the ocean has low viscosity, the westward obliquity tide does not move the crust. Therefore, crustal dissipation due to dynamical obliquity tides can differ from the static prediction by up to a factor of two.

Subsurface Ocean Tides in Enceladus and Other Icy Moons

NASA Astrophysics Data System (ADS)

Beuthe, M.

2016-12-01

Could tidal dissipation within Enceladus' subsurface ocean account for the observed heat flow? Earthlike models of dynamical tides give no definitive answer because they neglect the influence of the crust. I propose here the first model of dissipative tides in a subsurface ocean, by combining the Laplace Tidal Equations with the membrane approach. For the first time, it is possible to compute tidal dissipation rates within the crust, ocean, and mantle in one go. I show that oceanic dissipation is strongly reduced by the crustal constraint, and thus contributes little to Enceladus' present heat budget. Tidal resonances could have played a role in a forming or freezing ocean less than 100 meters deep. The model is general: it applies to all icy satellites with a thin crust and a shallow or stratified ocean. Scaling rules relate the resonances and dissipation rate of a subsurface ocean to the ones of a surface ocean. If the ocean has low viscosity, the westward obliquity tide does not move the crust. Therefore, crustal dissipation due to dynamical obliquity tides can differ from the static prediction by up to a factor of two.

Portrait of a Warming Ocean and Rising Sea Levels: Trend of Sea Level Change 1993-2008

NASA Technical Reports Server (NTRS)

2008-01-01

Warming water and melting land ice have raised global mean sea level 4.5 centimeters (1.7 inches) from 1993 to 2008. But the rise is by no means uniform. This image, created with sea surface height data from the Topex/Poseidon and Jason-1 satellites, shows exactly where sea level has changed during this time and how quickly these changes have occurred.

It's also a road map showing where the ocean currently stores the growing amount of heat it is absorbing from Earth's atmosphere and the heat it receives directly from the Sun. The warmer the water, the higher the sea surface rises. The location of heat in the ocean and its movement around the globe play a pivotal role in Earth's climate.

Light blue indicates areas in which sea level has remained relatively constant since 1993. White, red, and yellow are regions where sea levels have risen the most rapidly up to 10 millimeters per year and which contain the most heat. Green areas have also risen, but more moderately. Purple and dark blue show where sea levels have dropped, due to cooler water.

The dramatic variation in sea surface heights and heat content across the ocean are due to winds, currents and long-term changes in patterns of circulation. From 1993 to 2008, the largest area of rapidly rising sea levels and the greatest concentration of heat has been in the Pacific, which now shows the characteristics of the Pacific Decadal Oscillation (PDO), a feature that can last 10 to 20 years or even longer.

In this 'cool' phase, the PDO appears as a horseshoe-shaped pattern of warm water in the Western Pacific reaching from the far north to the Southern Ocean enclosing a large wedge of cool water with low sea surface heights in the eastern Pacific. This ocean/climate phenomenon may be caused by wind-driven Rossby waves. Thousands of kilometers long, these waves move from east to west on either side of the equator changing the distribution of water mass and heat.

This image of sea level trend also reveals a significant area of rising sea levels in the North Atlantic where sea levels are usually low. This large pool of rapidly rising warm water is evidence of a major change in ocean circulation. It signals a slow down in the sub-polar gyre, a counter-clockwise system of currents that loop between Ireland, Greenland and Newfoundland.

Such a change could have an impact on climate since the sub-polar gyre may be connected in some way to the nearby global thermohaline circulation, commonly known as the global conveyor belt. This is the slow-moving circulation in which water sinks in the North Atlantic at different locations around the sub-polar gyre, spreads south, travels around the globe, and slowly up-wells to the surface before returning around the southern tip of Africa. Then it winds its way through the surface currents in the Atlantic and eventually comes back to the North Atlantic.

It is unclear if the weakening of the North Atlantic sub-polar gyre is part of a natural cycle or related to global warming.

This image was made possible by the detailed record of sea surface height measurements begun by Topex/Poseidon and continued by Jason-1. The recently launched Ocean Surface Topography Mission on the Jason-2 satellite (OSTM/Jason-2) will soon take over this responsibility from Jason-1. The older satellite will move alongside OSTM/Jason-2 and continue to measure sea surface height on an adjacent ground track for as long as it is in good health.

Topex/Poseidon and Jason-1 are joint missions of NASA and the French space agency, CNES. OSTM/Jason-2 is collaboration between NASA; the National Oceanic and Atmospheric Administration; CNES; and the European Organisation for the Exploitation of Meteorological Satellites. JPL manages the U.S. portion of the missions for NASA's Science Mission Directorate, Washington, D.C.

KSC-2011-2759

NASA Image and Video Library

2011-04-02

VANDENBERG AIR FORCE BASE, Calif. -- An overhead crane moves the Aquarius/SAC-D spacecraft to cell 3 at the Spaceport Systems International payload processing facility at Vandenberg Air Force Base in California. There, the spacecraft will undergo inspection of its solar arrays and tests will be conducted on its propulsion subsystem. Further testing of the satellites various other systems will follow. Following final tests, the spacecraft will be integrated to a United Launch Alliance Delta II rocket in preparation for the targeted June launch. Aquarius, the NASA-built primary instrument on the SAC-D spacecraft, will map global changes in salinity at the ocean's surface. The three-year mission will provide new insights into how variations in ocean surface salinity relate to these fundamental climate processes. Photo credit: NASA/Randy Beaudoin, VAFB

Distant storms as drivers of environmental change at Pacific atolls.

PubMed

Gardner, Jonathan P A; Garton, David W; Collen, John D; Zwartz, Daniel

2014-01-01

The central Pacific Ocean with its many low lying islands and atolls is under threat from sea level rise and increased storm activity. Here, we illustrate how increasing frequency and severity of large scale storm events associated with global climate change may be particularly profound at the local scale for human populations that rely on lagoon systems for provision of a variety of goods and services. In August 2011 a storm originating in the Southern Ocean caused a large amplitude ocean swell to move northward through the Pacific Ocean. Its arrival at Palmyra Atoll coincided with transient elevated sea surface height and triggered turnover of the lagoon water column. This storm-induced change to the lagoon reflects long distance connectivity with propagated wave energy from the Southern Ocean and illustrates the increasing threats generated by climate change that are faced by human populations on most low-lying Pacific islands and atolls.

Distant Storms as Drivers of Environmental Change at Pacific Atolls

PubMed Central

Gardner, Jonathan P. A.; Garton, David W.; Collen, John D.; Zwartz, Daniel

2014-01-01

The central Pacific Ocean with its many low lying islands and atolls is under threat from sea level rise and increased storm activity. Here, we illustrate how increasing frequency and severity of large scale storm events associated with global climate change may be particularly profound at the local scale for human populations that rely on lagoon systems for provision of a variety of goods and services. In August 2011 a storm originating in the Southern Ocean caused a large amplitude ocean swell to move northward through the Pacific Ocean. Its arrival at Palmyra Atoll coincided with transient elevated sea surface height and triggered turnover of the lagoon water column. This storm-induced change to the lagoon reflects long distance connectivity with propagated wave energy from the Southern Ocean and illustrates the increasing threats generated by climate change that are faced by human populations on most low-lying Pacific islands and atolls. PMID:24498232

Long waves in the eastern equatorial pacific ocean: a view from a geostationary satellite.

PubMed

Legeckis, R

1977-09-16

During 1975, westward-moving long waves with a period of about 25 days and a wavelength of 1000 kilometers were observed at a sea surface temperature front in the equatorial Pacific on infrared images obtained by a geostationary environmental satellite system. The absence of these waves during 1976, and the above-average equatorial sea surface temperatures during 1976, may be related to a decrease in the southeasterly trade winds during that year.

Atlantic meridional heat transports computed from balancing Earth's energy locally: AMOC and Ocean Meridional Heat Transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trenberth, Kevin E.; Fasullo, John T.

The Atlantic Meridional Overturning Circulation plays a major role in moving heat and carbon around in the ocean. A new estimate of ocean heat transports for 2000 through 2013 throughout the Atlantic is derived. Top-of-atmosphere radiation is combined with atmospheric reanalyses to estimate surface heat fluxes and combined with vertically integrated ocean heat content to estimate ocean heat transport divergence as a residual. Atlantic peak northward ocean heat transports average 1.18 ± 0.13PW (1 sigma) at 15°N but vary considerably in latitude and time. Results agree well with observational estimates at 26.5°N from the RAPID array, but for 2004–2013 themore » meridional heat transport is 1.00 ± 0.11PW versus 1.23 ± 0.11PW for RAPID. In addition, these results have no hint of a trend, unlike the RAPID results. Finally, strong westerlies north of a meridian drive ocean currents and an ocean heat loss into the atmosphere that is exacerbated by a decrease in ocean heat transport northward.« less

Atlantic meridional heat transports computed from balancing Earth's energy locally: AMOC and Ocean Meridional Heat Transport

DOE PAGES

Trenberth, Kevin E.; Fasullo, John T.

2017-02-18

The Atlantic Meridional Overturning Circulation plays a major role in moving heat and carbon around in the ocean. A new estimate of ocean heat transports for 2000 through 2013 throughout the Atlantic is derived. Top-of-atmosphere radiation is combined with atmospheric reanalyses to estimate surface heat fluxes and combined with vertically integrated ocean heat content to estimate ocean heat transport divergence as a residual. Atlantic peak northward ocean heat transports average 1.18 ± 0.13PW (1 sigma) at 15°N but vary considerably in latitude and time. Results agree well with observational estimates at 26.5°N from the RAPID array, but for 2004–2013 themore » meridional heat transport is 1.00 ± 0.11PW versus 1.23 ± 0.11PW for RAPID. In addition, these results have no hint of a trend, unlike the RAPID results. Finally, strong westerlies north of a meridian drive ocean currents and an ocean heat loss into the atmosphere that is exacerbated by a decrease in ocean heat transport northward.« less

A process-level attribution of the annual cycle of surface temperature over the Maritime Continent

NASA Astrophysics Data System (ADS)

Li, Yana; Yang, Song; Deng, Yi; Hu, Xiaoming; Cai, Ming

2017-12-01

The annual cycle of the surface temperature over the Maritime Continent (MC) is characterized by two periods of rapid warming in March-April and September-October, respectively, and a period of rapid cooling in June-July. Based upon an analysis of energy balance within individual atmosphere-surface columns, the seasonal variations of surface temperature in the MC are partitioned into partial temperature changes associated with various radiative and non-radiative (dynamical) processes. The seasonal variations in direct solar forcing and surface latent heat flux show the largest positive contributions to the annual cycle of MC surface temperature while the changes in oceanic dynamics (including ocean heat content change) work against the temperature changes related to the annual cycle. The rapid warming in March-April is mainly a result of the changes in atmospheric quick processes and ocean-atmosphere coupling such as water vapor, surface latent heat flux, clouds, and atmospheric dynamics while the contributions from direct solar forcing and oceanic dynamics are negative. This feature is in contrast to that associated with the warming in September-October, which is driven mainly by the changes in solar forcing with a certain amount of contributions from water vapor and latent heat flux change. More contribution from atmospheric quick processes and ocean-atmosphere coupling in March-April coincides with the sudden northward movement of deep convection belt, while less contribution from these quick processes and coupling is accompanied with the convection belt slowly moving southward. The main contributors to the rapid cooling in June-July are the same as those to the rapid warming in March-April, and the cooling is also negatively contributed by direct solar forcing and oceanic dynamics. The changes in water vapor in all three periods contribute positively to the change in total temperature and they are associated with the change in the location of the center of large-scale moisture convergence during the onset and demise stages of the East Asian summer monsoon.

Upwelling Response to Hurricane Isaac in Geostrophic Oceanic Vortices

NASA Astrophysics Data System (ADS)

Jaimes, B.; Shay, L. K.; Brewster, J. K.; Schuster, R.

2013-05-01

As a tropical cyclone (TC) moves over the ocean, the cyclonic curl of the wind stress produces a region of upwelling waters under the TC center that is compensated by downwelling waters at regions outside the center. Direct measurements conducted during hurricane Rita and recent numerical studies indicate that this is not necessarily the case when TCs move over geostrophic oceanic features, where its background relative vorticity impacts wind-driven horizontal current divergence and the upwelling velocity. Modulation of the upwelling response in these energetic oceanic regimes impacts vertical mixing across the oceanic mixed layer base, air-sea fluxes into the atmosphere, and ultimately storm intensity. As part of NOAA Intensity Forecasting Experiment, an experiment was conducted during the passage of TC Isaac over the energetic geostrophic eddy field in the Gulf of Mexico in August 2012. Expendable bathythermographs, current profilers, and conductivity-temperature-depth probes were deployed in Isaac from NOAA WP-3D aircraft during four in-storm flights to measure oceanic variability and its impact on TC-driven upwelling and surface fluxes of heat and momentum. During intensification to hurricane, the cyclonic curl of the wind stress of Isaac extended over a region of more than 300 km in diameter (4 to 5 times the radius of maximum winds). Isaac's center moved over a cold cyclonic feature, while its right and left sides moved over warm anticyclones. Contrasting upwelling and downwelling regimes developed inside the region of cyclonic curl of the wind stress. Both positive (upwelling) and negative (downwelling) vertical displacements of 40 and 60 m, respectively, were measured inside the region of cyclonic curl of the wind stress, which are between 3 to 4 times larger than predicted vertical displacements for a quiescent ocean based on scaling arguments. Oceanic mixed layer (OML) currents of 0.2 to 0.7 m s-1 were measured, which are about 50% smaller than the expected velocity response under quiescent oceanic conditions. Although OML currents were measured inside the core of cyclonic curl of the wind stress, their orientation is not consistent with horizontally divergent flows typically found in upwelling regimes under TC centers. Theoretical predictions that consider background relative vorticity effects on the upwelling response mimic the contrasting upwelling/downwelling regimes inside the region of cyclonic curl of the wind stress. These results point to an important modulation of the OML current and upwelling response by background oceanic flows, where the upwelling velocity is a function of the curl of wind-intensified pre-storm geostrophic currents, rather than just a function of the curl of the wind stress. Thus, properly initializing temperature and salinity fields in numerical models is needed to accurately represent these oceanic processes in coupled forecast models.

Oceanic circulation models help to predict global biogeography of pelagic yellow-bellied sea snake.

PubMed

Brischoux, François; Cotté, Cédric; Lillywhite, Harvey B; Bailleul, Frédéric; Lalire, Maxime; Gaspar, Philippe

2016-08-01

It is well recognized that most marine vertebrates, and especially tetrapods, precisely orient and actively move in apparently homogeneous oceanic environments. Here, we investigate the presumptive role of oceanic currents in biogeographic patterns observed in a secondarily marine tetrapod, the yellow-bellied sea snake (Hydrophis [Pelamis] platurus). State-of-the-art world ocean circulation models show how H. platurus, the only pelagic species of sea snake, can potentially exploit oceanic currents to disperse and maintain population mixing between localities that spread over two-thirds of the Earth's circumference. The very close association of these snakes with surface currents seems to provide a highly efficient dispersal mechanism that allowed this species to range extensively and relatively quickly well beyond the central Indo-Pacific area, the centre of origin, abundance and diversity of sea snakes. Our results further suggest that the pan-oceanic population of this species must be extraordinarily large. © 2016 The Author(s).

Does size and buoyancy affect the long-distance transport of floating debris?

NASA Astrophysics Data System (ADS)

Ryan, Peter G.

2015-08-01

Floating persistent debris, primarily made from plastic, disperses long distances from source areas and accumulates in oceanic gyres. However, biofouling can increase the density of debris items to the point where they sink. Buoyancy is related to item volume, whereas fouling is related to surface area, so small items (which have high surface area to volume ratios) should start to sink sooner than large items. Empirical observations off South Africa support this prediction: moving offshore from coastal source areas there is an increase in the size of floating debris, an increase in the proportion of highly buoyant items (e.g. sealed bottles, floats and foamed plastics), and a decrease in the proportion of thin items such as plastic bags and flexible packaging which have high surface area to volume ratios. Size-specific sedimentation rates may be one reason for the apparent paucity of small plastic items floating in the world’s oceans.

How ocean color can steer Pacific tropical cyclones

NASA Astrophysics Data System (ADS)

Gnanadesikan, Anand; Emanuel, Kerry; Vecchi, Gabriel A.; Anderson, Whit G.; Hallberg, Robert

2010-09-01

Because ocean color alters the absorption of sunlight, it can produce changes in sea surface temperatures with further impacts on atmospheric circulation. These changes can project onto fields previously recognized to alter the distribution of tropical cyclones. If the North Pacific subtropical gyre contained no absorbing and scattering materials, the result would be to reduce subtropical cyclone activity in the subtropical Northwest Pacific by 2/3, while concentrating cyclone tracks along the equator. Predicting tropical cyclone activity using coupled models may thus require consideration of the details of how heat moves into the upper thermocline as well as biogeochemical cycling.

KSC-08pd1290

NASA Image and Video Library

2008-04-29

VANDENBERG AIR FORCE BASE, Calif. -- At Vandenberg Air Force Base, the OSTM/Jason-2 satellite shipping container is being moved inside the Astrotech processing facility. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

KSC-08pd1292

NASA Image and Video Library

2008-04-29

VANDENBERG AIR FORCE BASE, Calif. -- At Vandenberg Air Force Base, the OSTM/Jason-2 satellite shipping container has been moved inside the Astrotech processing facility. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

KSC-08pd1291

NASA Image and Video Library

2008-04-29

VANDENBERG AIR FORCE BASE, Calif. -- At Vandenberg Air Force Base, the OSTM/Jason-2 satellite shipping container is being moved inside the Astrotech processing facility. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

Rocks of the early lunar crust

NASA Technical Reports Server (NTRS)

James, O. B.

1980-01-01

Data are summarized which suggest a model for the early evolution of the lunar crust. According to the model, during the final stages of accretion, the outer part of the moon melted to form a magma ocean approximately 300 km deep. This ocean fractionated to form mafic and ultramafic cumulates at depth and an overlying anorthositic crust made up of ferroan anorthosites. Subsequent partial melting in the primitive mantle underlying the crystallized magma ocean produced melts which segregated, moved upward, intruded the primordial crust, and crystallized to form layered plutons consisting of Mg-rich plutonic rocks. Intense impact bombardment at the lunar surface mixed and melted the rocks of the two suites to form a thick layer of granulated debris, granulitic breccias, and impact-melt rocks.

Numerical Simulation of Tethered Underwater Kites for Power Generation

NASA Astrophysics Data System (ADS)

Ghasemi, Amirmahdi; Olinger, David; Tryggvason, Gretar

2015-11-01

An emerging renewable energy technology, tethered undersea kites (TUSK), which is used to extract hydrokinetic energy from ocean and tidal currents, is studied. TUSK systems consist of a rigid-winged ``kite,'' or glider, moving in an ocean current which is connected by tethers to a floating buoy on the ocean surface. The TUSK kite is a current speed enhancement device since the kite can move in high-speed, cross-current motion at 4-6 times the current velocity, thus producing more power than conventional marine turbines. A computational simulation is developed to simulate the dynamic motion of an underwater kite and extendable tether. A two-step projection method within a finite volume formulation, along with an Open MP acceleration method, is employed to solve the Navier-Stokes equations. An immersed boundary method is incorporated to model the fluid-structure interaction of the rigid kite (with NACA 0012 airfoil shape in 2D and NACA 0021 airfoil shape in 3D simulations) and the fluid flow. PID control methods are used to adjust the kite angle of attack during power (tether reel-out) and retraction (reel-in) phases. Two baseline simulations (for kite motions in two and three dimensions) are studied, and system power output, flow field vorticity, tether tension, and hydrodynamic coefficients (lift and drag) for the kite are determined. The simulated power output shows good agreement with established theoretical results for a kite moving in two-dimensions.

Effects of elastic bed on hydrodynamic forces for a submerged sphere in an ocean of finite depth

NASA Astrophysics Data System (ADS)

Mohapatra, Smrutiranjan

2017-08-01

In this paper, we consider a hydroelastic model to examine the radiation of waves by a submerged sphere for both heave and sway motions in a single-layer fluid flowing over an infinitely extended elastic bottom surface in an ocean of finite depth. The elastic bottom is modeled as a thin elastic plate and is based on the Euler-Bernoulli beam equation. The effect of the presence of surface tension at the free-surface is neglected. In such situation, there exist two modes of time-harmonic waves: the one with a lower wavenumber (surface mode) propagates along the free-surface and the other with higher wavenumber (flexural mode) propagates along the elastic bottom surface. Based on the small amplitude wave theory and by using the multipole expansion method, we find the particular solution for the problem of wave radiation by a submerged sphere of finite depth. Furthermore, this method eliminates the need to use large and cumbersome numerical packages for the solution of such problem and leads to an infinite system of linear algebraic equations which are easily solved numerically by any standard technique. The added-mass and damping coefficients for both heave and sway motions are derived and plotted for different submersion depths of the sphere and flexural rigidity of the elastic bottom surface. It is observed that, whenever the sphere nearer to the elastic bed, the added-mass move toward to a constant value of 1, which is approximately twice of the value of added-mass of a moving sphere in a single-layer fluid flowing over a rigid and flat bottom surface.

KSC-2011-2751

NASA Image and Video Library

2011-04-02

VANDENBERG AIR FORCE BASE, Calif. -- The Aquarius/SAC-D spacecraft is being prepared for its move to cell 3 at the Spaceport Systems International payload processing facility at Vandenberg Air Force Base in California. There, the spacecraft will undergo inspection of its solar arrays and tests will be conducted on its propulsion subsystem. Further testing of the satellites various other systems will follow. Following final tests, the spacecraft will be integrated to a United Launch Alliance Delta II rocket in preparation for the targeted June launch. Aquarius, the NASA-built primary instrument on the SAC-D spacecraft, will map global changes in salinity at the ocean's surface. The three-year mission will provide new insights into how variations in ocean surface salinity relate to these fundamental climate processes. Photo credit: NASA/Randy Beaudoin, VAFB

KSC-2011-2753

NASA Image and Video Library

2011-04-02

VANDENBERG AIR FORCE BASE, Calif. -- Technicians prepare the Aquarius/SAC-D spacecraft for its move to cell 3 at the Spaceport Systems International payload processing facility at Vandenberg Air Force Base in California. There, the spacecraft will undergo inspection of its solar arrays and tests will be conducted on its propulsion subsystem. Further testing of the satellites various other systems will follow. Following final tests, the spacecraft will be integrated to a United Launch Alliance Delta II rocket in preparation for the targeted June launch. Aquarius, the NASA-built primary instrument on the SAC-D spacecraft, will map global changes in salinity at the ocean's surface. The three-year mission will provide new insights into how variations in ocean surface salinity relate to these fundamental climate processes. Photo credit: NASA/Randy Beaudoin, VAFB

On using the Multiple Signal Classification algorithm to study microbaroms

NASA Astrophysics Data System (ADS)

Marcillo, O. E.; Blom, P. S.; Euler, G. G.

2016-12-01

Multiple Signal Classification (MUSIC) (Schmidt, 1986) is a well-known high-resolution algorithm used in array processing for parameter estimation. We report on the application of MUSIC to infrasonic array data in a study of the structure of microbaroms. Microbaroms can be globally observed and display energy centered around 0.2 Hz. Microbaroms are an infrasonic signal generated by the non-linear interaction of ocean surface waves that radiate into the ocean and atmosphere as well as the solid earth in the form of microseisms. Microbaroms sources are dynamic and, in many cases, distributed in space and moving in time. We assume that the microbarom energy detected by an infrasonic array is the result of multiple sources (with different back-azimuths) in the same bandwidth and apply the MUSIC algorithm accordingly to recover the back-azimuth and trace velocity of the individual components. Preliminary results show that the multiple component assumption in MUSIC allows one to resolve the fine structure in the microbarom band that can be related to multiple ocean surface phenomena.

A review on the sources and spatial-temporal distributions of Pb in Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Yang, Dongfang; Zhang, Jie; Wang, Ming; Zhu, Sixi; Wu, Yunjie

2017-12-01

This paper provided a review on the source, spatial-distribution, temporal variations of Pb in Jiaozhou Bay based on investigation of Pb in surface and waters in different seasons during 1979-1983. The source strengths of Pb sources in Jiaozhou Bay were showing increasing trends, and the pollution level of Pb in this bay was slight or moderate in the early stage of reform and opening-up. Pb contents in the marine bay were mainly determined by the strength and frequency of Pb inputs from human activities, and Pb could be moving from high content areas to low content areas in the ocean interior. Surface waters in the ocean was polluted by human activities, and bottom waters was polluted by means of vertical water’s effect. The process of spatial distribution of Pb in waters was including three steps, i.e., 1), Pb was transferring to surface waters in the bay, 2) Pb was transferring to surface waters, and 3) Pb was transferring to and accumulating in bottom waters.

Upper ocean response to the passage of two sequential typhoons

NASA Astrophysics Data System (ADS)

Wu, Renhao; Li, Chunyan

2018-02-01

Two sequential typhoons, separated by five days, Chan-hom and Nangka in the summer of 2015, provided a unique opportunity to study the oceanic response and cold wake evolution. The upper ocean response to the passage of these two typhoons was investigated using multi-satellite, Argo float data and HYCOM global model output. The sea surface cooling (SSC) induced by Chan-hom was gradually enhanced along its track when the storm was intensified while moving over the ocean with shallow mixed layer. The location of maximum cooling of sea surface was determined by the storm's translation speed as well as pre-typhoon oceanic conditions. As a fast-moving storm, Chan-hom induced significant SSC on the right side of its track. Localized maximum cooling patches are found over a cyclonic eddy (CE). An analysis of data from Argo floats near the track of Chan-hom demonstrated that the mixed layer temperature (MLT) and mixed layer depth (MLD) had more variabilities on the right side than those on the left side of Chan-hom's track, while mixed layer salinity (MLS) response was different from those of MLT and MLD with an increase in salinity to the right side and a decrease in salinity to the left side of the track. Subsequently, because of the remnant effect of Chan-hom, the strong upwelling induced by Typhoon Nangka, the pre-existing CE as well as a slow translation speed (<2 m s-1) of the storm, the most significant SSC ( 6 °C) was observed over the CE region in the wake of the storm. Further, Nangka experienced a rapid weakening suggesting immediate negative feedback from the intensified SSC occurred in the CE region. After these two typhoons, the CE was enhanced and the sea surface height of eddy core was depressed by 10 cm. It took more than one month for SSC to restore to its pre-typhoon conditions, with the anomalous geostrophic current advection playing an important role in the process. The enhancement of chlorophyll-a concentrations was also noticed at both the CE region and close to Chan-hom's track.

Geodynamic modeling of the capture and release of a plume conduit by a migrating mid-ocean ridge

NASA Astrophysics Data System (ADS)

Hall, P. S.

2011-12-01

plates over the relatively stationary, long-lived conduits of mantle plumes. However, paleomagnetic data from the Hawaii-Emperor Seamount Chain suggests that the Hawaiian hotspot moved rapidly (~40 mm/yr) between 81 - 47 Ma [Tarduno et al., 2003]. Recently, Tarduno et al. [2009] suggested that this period of rapid motion might be the surface expression of a plume conduit returning to a largely vertical orientation after having been captured and tilted as the result of being "run over" by migrating mid-ocean ridge. I report on a series of analog geodynamic experiments designed to characterize the evolution of a plume conduit as a mid-ocean ridge migrates over. Experiments were conducted in a clear acrylic tank (100 cm x 70 cm x 50 cm) filled with commercial grade high-fructose corn syrup. Plate-driven flow is modeled by dragging two sheets of Mylar film (driven by independent DC motors) in opposite directions over the surface of the fluid. Ridge migration is achieved by moving the point at which the mylar sheets diverge using a separate motor drive. Buoyant plume flow is generated using a small electrical heater placed at the bottom of the tank. Plate velocities and ridge migration rate are controlled and plume temperature monitored using LabView software. Experiments are recorded using digital video which is then analyzed using digital image analysis software to track the position and shape of the plume conduit throughout the course of the experiment. The intersection of the plume conduit with the surface of the fluid is taken as an analog for the locus of hotspot volcanism and tracked as a function of time to obtain a hotspot migration rate. Results show that the plume conduit experiences significant tilting immediately following the passage of the migrating ridge.

Westerly Wind Events in the Eastern Indian Ocean as a Precursor to El Nino: A Case Study for the 2002-03 El Nino

NASA Technical Reports Server (NTRS)

Curtis, Scott; Adler, Robert F.; Huffman, George J.; Gu, Guojun

2003-01-01

This paper extends the work of our previous study, which showed the potential of using precipitation in the eastern Indian Ocean to predict when an El Nino would begin. The paper begins by showing the successful prediction of the 2002-03 El Nino. However, precipitation is really used as a substitute for wind (storms are usually accompanied by heavy wind), because a popular hypothesis is that winds (especially % winds out of the West) stir up the ocean surface in the western Pacific sending currents of warm waters to the east Pacific where El Ninos form. This paper shows that it is typical for storms that produce strong winds in the western Pacific to have traveled from the Indian Ocean. We begin in the Indian Ocean looking at strong bursts of wind over several days. The number of windy days seems to increase in the months prior to El Nino. We examined these relationships in detail for November 2001 to April 2002, before the recent El Nino, using NASA's TRMM and QuikSCAT data. We found in one case that a warming of the eastern Indian Ocean occurred about 25 days before heavy rainfall formed. As the stormed moved eastward it was followed (6 days later) by strong winds out of the West. The entire storm system (and warming of the sea) moved eastward through a small strip of water between Indonesia and Australia, before reaching the western Pacific. Thus, this paper increases our understanding of the physical processes leading to the formation of El Nino.

The Influence of Ocean on Typhoon Nuri (2008)

NASA Astrophysics Data System (ADS)

Sun, J.; Oey, L. Y.; Xu, F.; Lin, Y.; Huang, S. M.; Chang, R.

2014-12-01

The influence of ocean on typhoon Nuri (2008) is investigated in this study using the WRF numerical model. Typhoon Nuri formed over the warm pool of the western North Pacific. The storm traversed west-northwestward and became a Category 3 typhoon over the Kuroshio east of the Luzon Strait and weakened as it moved across South China Sea. Three types of SST: NCEP RTG_SST (Real-time，global，sea surface temperature) GHRsst (Group for High Resolution Sea Surface Temperature) and SST from the ATOP North Pacific ocean model [Oey et al 2014, JPO] are used in WRF to test the effect of ocean on the intensity of typhoon Nuri. The typhoon intensity and track are also compared with simulations using different microphysics schemes but with fixed SST. The results show that thermodynamic control through ocean response is the dominant factor which determines Nuri's intensity. The simulated intensity agrees well with the observed intensity when ATOP SST is used, while using NCEP SST and GHRsst yield errors both in intensity and timing of maximum intensity. Over the Kuroshio, the thicker depth of 26 ℃ from ATOP provides stronger heating for the correct timing of intensification of Nuri. In South China Sea, the storm weakened because of cooled SST through ocean mixing by inertial resonance. A new way of explaining typhoon intensification though PV is proposed.

Global assessment of Level 3 SMOS and Aquarius salinity measurements using Argo and an operational ocean model

NASA Astrophysics Data System (ADS)

Banks, Chris; Gommenginger, Christine; Srokosz, Meric; Snaith, Helen

2013-04-01

The launch of the European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) satellite in November 2009 marked a new era in satellite oceanography. SMOS was joined in orbit, in June 2011, by the NASA/Argentine Aquarius/SAC-D mission, specifically designed to measure sea surface salinity (SSS). These two satellites have significantly improved our ability to measure SSS synoptically. Despite significant differences in how the two satellites estimate SSS, both utilise passive systems to measure the response of the brightness temperature (Tb) at L-band (1.4 GHz) to SSS and initial results are encouraging. The UK National Oceanography Centre has produced 'Level 3' SSS data products for SMOS and Aquarius using monthly data on a 1° by 1° global grid, between 60°S and 60°N, from 1 September 2011 to 31 August 2012. Previous and on-going work shows for both satellites significant temporally varying differences between SSS from ascending passes (satellite moving south to north) and SSS from descending passes (satellite moving north to south). Therefore, for both SMOS and Aquarius, separate Level 3 products are produced from data for ascending and descending passes. For this study, two separate monthly validation datasets are used based on the same grid as the satellite data. The first is averaged near-surface salinity (depth less than 10 m) as derived from the drifting Argo float programme. The second validation data source is output from the UK Met Office Forecasting Ocean Assimilation Model (FOAM), which is based on NEMO (Nucleus for European Modelling of the Ocean). We calculate maps of the difference between all possible pairs of SSS data for each month, and consider their relationships using regression on the 1˚ values. The analysis is carried out for the global ocean, as well as for smaller, more homogeneous, study regions (e.g. SPURS in the subtropical North Atlantic).

Numerical investigation of hydrodynamic flow over an AUV moving in the water-surface vicinity considering the laminar-turbulent transition

NASA Astrophysics Data System (ADS)

Salari, Mahmoud; Rava, Amin

2017-09-01

Nowadays, Autonomous Underwater Vehicles (AUVs) are frequently used for exploring the oceans. The hydrodynamics of AUVs moving in the vicinity of the water surface are significantly different at higher depths. In this paper, the hydrodynamic coefficients of an AUV in non-dimensional depths of 0.75, 1, 1.5, 2, and 4D are obtained for movement close to the free-surface. Reynolds Averaged Navier Stokes Equations (RANS) are discretized using the finite volume approach and the water-surface effects modeled using the Volume of Fraction (VOF) method. As the operating speeds of AUVs are usually low, the boundary layer over them is not fully laminar or fully turbulent, so the effect of boundary layer transition from laminar to turbulent flow was considered in the simulations. Two different turbulence/transition models were used: 1) a full-turbulence model, the k-ɛ model, and 2) a turbulence/transition model, Menter's Transition-SST model. The results show that the Menter's Transition-SST model has a better consistency with experimental results. In addition, the wave-making effects of these bodies are studied at different immersion depths in the sea-surface vicinity or at finite depths. It is observed that the relevant pitch moments and lift coefficients are non-zero for these axi-symmetric bodies when they move close to the sea-surface. This is not expected for greater depths.

KSC-2011-1960

NASA Image and Video Library

2011-03-01

VANDENBERG AIR FORCE BASE, Calif. -- As the sun rises over Vandenberg Air Force Base in California, the first stage of the United Launch Alliance Delta II rocket that will carry the Aquarius/SAC-D satellite into low Earth orbit is prepared for its move to Space Launch Complex-2 (SLC-2). Scheduled to launch in June, Aquarius' mission will be to provide monthly maps of global changes in sea surface salinity. By measuring ocean salinity from space, Aquarius will provide new insights into how the massive natural exchange of freshwater between the ocean, atmosphere and sea ice influences ocean circulation, weather and climate. Also going up with the satellite are optical and thermal cameras, a microwave radiometer and the SAC-D spacecraft, which were developed with the help of institutions in Italy, France, Canada and Argentina. Photo credit: NASA/VAFB

KSC-08pd1305

NASA Image and Video Library

2008-04-30

VANDENBERG AIR FORCE BASE, Calif. -- Inside the Astrotech processing facility at Vandenberg Air Force Base, the OSTM/Jason-2 spacecraft is lifted from its stand to be moved to a tilt dolly. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Mark Mackley

KSC-08pd1304

NASA Image and Video Library

2008-04-30

VANDENBERG AIR FORCE BASE, Calif. -- Inside the Astrotech processing facility at Vandenberg Air Force Base, technicians check the OSTM/Jason-2 spacecraft before it is moved to a tilt dolly. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Mark Mackley

KSC-08pd1289

NASA Image and Video Library

2008-04-29

VANDENBERG AIR FORCE BASE, Calif. -- In front of the Astrotech processing facility at Vandenberg Air Force Base, the OSTM/Jason-2 satellite shipping container is on the ground, ready to be moved inside. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

KSC-08pd1293

NASA Image and Video Library

2008-04-30

VANDENBERG AIR FORCE BASE, Calif. -- Inside the Astrotech processing facility at Vandenberg Air Force Base, an overhead crane is moved over the OSTM/Jason-2 spacecraft to lift off the shipping container. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Mark Mackley

KSC-08pd1303

NASA Image and Video Library

2008-04-30

VANDENBERG AIR FORCE BASE, Calif. -- Inside the Astrotech processing facility at Vandenberg Air Force Base, a technician (right) checks the OSTM/Jason-2 spacecraft before it is moved to a tilt dolly. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Mark Mackley

KSC-08pd1306

NASA Image and Video Library

2008-04-30

VANDENBERG AIR FORCE BASE, Calif. -- Inside the Astrotech processing facility at Vandenberg Air Force Base, the OSTM/Jason-2 spacecraft is moved to a tilt dolly. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Mark Mackley

Motions of Australia and surroundings since 43 Ma as recorded by subducted mantle lithosphere--evidence for a lost ocean between the Pacific and Indian Oceans

NASA Astrophysics Data System (ADS)

Renqi, L.; Wu, J. E.; Suppe, J.; Kanda, R. V.

2013-12-01

It is well known from seafloor spreading and hotspot data that the Australian plate has moved ~2500km northward in a mantle reference frame since 43Ma, during which time the Pacific plate moved approximately orthogonally ~3000km in a WNW direction. In addition the Australian plate has expanded up to 2000 km as a result of back arc spreading associated with evolving subduction systems on its northern and eastern margins. Here we attempt to account for this plate motion and subduction using new quantitative constraints of mapped slabs of subducted mantle lithosphere underlying the Australian plate and its surroundings. We have mapped a large swath of sub-horizontal slabs in the lower mantle under onshore and offshore NE Australia using global mantle seismic tomography. When restored together with other mapped slabs from the Asia Pacific region, these slabs reveal the existence of a major ocean between NE Australia, E. Asian, and the Pacific at 43 Ma, which we call the East Asian Sea. The southern half of this East Asian Sea was overrun and completely subducted by northward-moving Australia and the expanding Melanesian arcs, and the WNW-converging Pacific. This lost ocean fills a major gap in plate tectonic reconstructions and also constraints the possible motion of the Caroline Sea and New Guinea arcs. Slabs were mapped from MITP08 global P-wave seismic tomography data (Li and Hilst, 2008) and the TX2011 S-wave seismic tomography data (Grand and Simmons, 2011) using Gocad software. The mapped slabs were unfolded to the spherical Earth surface to assess their pre-subduction geometry. Gplates software was used to constrain plate tectonic reconstructions within a fully animated, globally consistent framework.

KSC-2011-2758

NASA Image and Video Library

2011-04-02

VANDENBERG AIR FORCE BASE, Calif. -- Technicians monitor the Aquarius/SAC-D spacecraft as it is being moved by an overhead crane from its stand to cell 3 at the Spaceport Systems International payload processing facility at Vandenberg Air Force Base in California. There, the spacecraft will undergo inspection of its solar arrays and tests will be conducted on its propulsion subsystem. Further testing of the satellites various other systems will follow. Following final tests, the spacecraft will be integrated to a United Launch Alliance Delta II rocket in preparation for the targeted June launch. Aquarius, the NASA-built primary instrument on the SAC-D spacecraft, will map global changes in salinity at the ocean's surface. The three-year mission will provide new insights into how variations in ocean surface salinity relate to these fundamental climate processes. Photo credit: NASA/Randy Beaudoin, VAFB

KSC-2011-2757

NASA Image and Video Library

2011-04-02

VANDENBERG AIR FORCE BASE, Calif. -- Technicians monitor the Aquarius/SAC-D spacecraft as it is being moved by an overhead crane from its stand to cell 3 at the Spaceport Systems International payload processing facility at Vandenberg Air Force Base in California. There, the spacecraft will undergo inspection of its solar arrays and tests will be conducted on its propulsion subsystem. Further testing of the satellites various other systems will follow. Following final tests, the spacecraft will be integrated to a United Launch Alliance Delta II rocket in preparation for the targeted June launch. Aquarius, the NASA-built primary instrument on the SAC-D spacecraft, will map global changes in salinity at the ocean's surface. The three-year mission will provide new insights into how variations in ocean surface salinity relate to these fundamental climate processes. Photo credit: NASA/Randy Beaudoin, VAFB

Theory and measure of certain image norms in SAR

NASA Technical Reports Server (NTRS)

Raney, R. K.

1984-01-01

The principal properties of synthetic aperture radar SAR imagery of point and distributed objects are summarized. Against this background, the response of a SAR (Synthetic Aperture Radar) to the moving surface of the sea is considered. Certain conclusions are drawn as to the mechanism of interaction between microwaves and the sea surface. Focus and speckle spectral tests may be used on selected SAR imagery for areas of the ocean. The fine structure of the sea imagery is sensitive to processor focus and adjustment. The ocean reflectivity mechanism must include point like scatterers of sufficient radar cross section to dominate the return from certain individual resolution elements. Both specular and diffuse scattering mechanisms are observed together, to varying degree. The effect is sea state dependent. Several experiments are proposed based on imaging theory that could assist in the investigation of reflectivity mechanisms.

Sea ice and surface water circulation, Alaskan continental shelf

NASA Technical Reports Server (NTRS)

Wright, F. F. (Principal Investigator); Sharma, G. D.; Burns, J. J.

1973-01-01

The author has identified the following significant results. Sediments contributed by the Copper River in the Gulf of Alaska are carried westward along the shore as a distinct plume. Oceanic water relatively poor in suspended material appears to intrude near Montague Island, and turbid water between Middleton Island and Kayak Island is the result of Ekman between transport. An anticlockwise surface water circulation is observed in this region. Ground truth data indicate striking similarity with ERTS-1 imagery obtained on October 12, 1972. Observations of ERTS-1 imagery reveal that various characteristics and distribution of sea ice in the Arctic Ocean can be easily studied. Formation of different types of sea ice and their movement is quite discrenible. Sea ice moves parallel to the cost in near shore areas and to the northerly direction away from the coast.

STS-41G earth observations

NASA Image and Video Library

1984-10-12

41G-34-098 (5-13 Oct 1984) --- Strait of Gibraltar and western Mediterranean photographed sunglint. Sun reflection on water delineates surface texture, which corresponds to the ocean's dynamics. The large group of waves connecting Gibraltar with the Moroccan coast is the response of the ocean to a tidal pulse moving into the Mediterranean. The low level wing shear line extending out from the Moroccan coastline into the Mediterranean for approximately 40 miles is the southern extremity of the wind funneling through the strait. This is the first high resolution photograph ever taken of this phenomenon permitting detailed delineation of individual waves which comprise the wave packet.

A biologically relevant method for considering patterns of oceanic retention in the Southern Ocean

NASA Astrophysics Data System (ADS)

Mori, Mao; Corney, Stuart P.; Melbourne-Thomas, Jessica; Klocker, Andreas; Sumner, Michael; Constable, Andrew

2017-12-01

Many marine species have planktonic forms - either during a larval stage or throughout their lifecycle - that move passively or are strongly influenced by ocean currents. Understanding these patterns of movement is important for informing marine ecosystem management and for understanding ecological processes generally. Retention of biological particles in a particular area due to ocean currents has received less attention than transport pathways, particularly for the Southern Ocean. We present a method for modelling retention time, based on the half-life for particles in a particular region, that is relevant for biological processes. This method uses geostrophic velocities at the ocean surface, derived from 23 years of satellite altimetry data (1993-2016), to simulate the advection of passive particles during the Southern Hemisphere summer season (from December to March). We assess spatial patterns in the retention time of passive particles and evaluate the processes affecting these patterns for the Indian sector of the Southern Ocean. Our results indicate that the distribution of retention time is related to bathymetric features and the resulting ocean dynamics. Our analysis also reveals a moderate level of consistency between spatial patterns of retention time and observations of Antarctic krill (Euphausia superba) distribution.

Observations of transport of bacterial-like microspheres through beach sand

NASA Astrophysics Data System (ADS)

Gast, Rebecca J.; Elgar, Steve; Raubenheimer, Britt

2015-04-01

Often, there is an order of magnitude more fecal indicator bacteria (enterococci) in beach sand than in nearby water. Consequently, sand is considered a reservoir for these bacteria, potentially contributing to poor water quality, and raising questions regarding the human health risks associated with sand exposure. An integral aspect of the distribution and persistence of sand-associated enterococci is the transport of bacteria introduced into the beach environment. Here, plastic microspheres are used as a proxy to examine the wave-induced movement of bacterial-like particles through sand on an ocean beach. Laboratory tests suggest microspheres and bacteria move similarly through sand columns, and have qualitatively similar short-term adsorption-to-sand behavior. Microspheres buried ~0.05 m below the sand surface on an ocean beach moved rapidly [O(10-3) m/s] away from their initial location, both vertically into the ground water below the sand and horizontally seaward within the sediment matrix in response to waves running up the beach face and percolating through the sand.

OceanSITES: Sustained Ocean Time Series Observations in the Global Ocean.

NASA Astrophysics Data System (ADS)

Weller, R. A.; Gallage, C.; Send, U.; Lampitt, R. S.; Lukas, R.

2016-02-01

Time series observations at critical or representative locations are an essential element of a global ocean observing system that is unique and complements other approaches to sustained observing. OceanSITES is an international group of oceanographers associated with such time series sites. OceanSITES exists to promote the continuation and extension of ocean time series sites around the globe. It also exists to plan and oversee the global array of sites in order to address the needs of research, climate change detection, operational applications, and policy makers. OceanSITES is a voluntary group that sits as an Action Group of the JCOMM-OPS Data Buoy Cooperation Panel, where JCOMM-OPS is the operational ocean observing oversight group of the Joint Commission on Oceanography and Marine Meteorology of the International Oceanographic Commission and the World Meteorological Organization. The way forward includes working to complete the global array, moving toward multidisciplinary instrumentation on a subset of the sites, and increasing utilization of the time series data, which are freely available from two Global Data Assembly Centers, one at the National Data Buoy Center and one at Coriolis at IFREMER. One recnet OceanSITES initiative and several results from OceanSITES time series sites are presented. The recent initiative was the assembly of a pool of temperature/conductivity recorders fro provision to OceanSITES sites in order to provide deep ocean temperature and salinity time series. Examples from specific sites include: a 15-year record of surface meteorology and air-sea fluxes from off northern Chile that shows evidence of long-term trends in surface forcing; change in upper ocean salinity and stratification in association with regional change in the hydrological cycle can be seen at the Hawaii time series site; results from monitoring Atlantic meridional transport; and results from a European multidisciplinary time series site.

An analytical model of iceberg drift

NASA Astrophysics Data System (ADS)

Eisenman, I.; Wagner, T. J. W.; Dell, R.

2017-12-01

Icebergs transport freshwater from glaciers and ice shelves, releasing the freshwater into the upper ocean thousands of kilometers from the source. This influences ocean circulation through its effect on seawater density. A standard empirical rule-of-thumb for estimating iceberg trajectories is that they drift at the ocean surface current velocity plus 2% of the atmospheric surface wind velocity. This relationship has been observed in empirical studies for decades, but it has never previously been physically derived or justified. In this presentation, we consider the momentum balance for an individual iceberg, which includes nonlinear drag terms. Applying a series of approximations, we derive an analytical solution for the iceberg velocity as a function of time. In order to validate the model, we force it with surface velocity and temperature data from an observational state estimate and compare the results with iceberg observations in both hemispheres. We show that the analytical solution reduces to the empirical 2% relationship in the asymptotic limit of small icebergs (or strong winds), which approximately applies for typical Arctic icebergs. We find that the 2% value arises due to a term involving the drag coefficients for water and air and the densities of the iceberg, ocean, and air. In the opposite limit of large icebergs (or weak winds), which approximately applies for typical Antarctic icebergs with horizontal length scales greater than about 12 km, we find that the 2% relationship is not applicable and that icebergs instead move with the ocean current, unaffected by the wind. The two asymptotic regimes can be understood by considering how iceberg size influences the relative importance of the wind and ocean current drag terms compared with the Coriolis and pressure gradient force terms in the iceberg momentum balance.

Undergraduate Research Experience in Ocean/Marine Science (URE-OMS) with African Student Component

DTIC Science & Technology

2008-01-01

Intergovernmental Panel on Climate Change (IPCC). RESULTS Temporal and Spatial Variations of Sea Surface Temperature and Chlorophyll a in Coastal Waters of...Duck, North Carolina [4] Climate change has affected the North Carolina coastal environments and coastal hazards have already taken place in the area...from geological materials (sands, dead and/or bleached corals ...etc) shifted by waves, tides, and currents moving sediments and eroding shorelines

Integrating surface and mantle constraints for palaeo-ocean evolution: a tour of the Arctic and adjacent regions (Arne Richter Award for Outstanding Young Scientists Lecture)

NASA Astrophysics Data System (ADS)

Shephard, Grace E.

2016-04-01

Plate tectonic reconstructions heavily rely on absolute motions derived from hotspot trails or palaeomagnetic data and ocean-floor magnetic anomaies and fracture-zone geometries to constrain the detailed history of ocean basins. However, as oceanic lithosphere is progressively recycled into the mantle, kinematic data regarding the history of these now extinct-oceans is lost. In order to better understand their evolution, novel workflows, which integrate a wide range of complementary yet independent geological and geophysical datasets from both the surface and deep mantle, must be utilised. In particular, the emergence of time-dependent, semi or self-consistent geodynamic models of ever-increasing temporal and spatial resolution are revealing some critical constraints on the evolution and fate of oceanic slabs. The tectonic evolution of the circum-Arctic is no exception; since the breakup of Pangea, this enigmatic region has seen major plate reorganizations and the opening and closure of several ocean basins. At the surface, a myriad of potential kinematic scenarios including polarity, timing, geometry and location of subduction have emerged, including for systems along continental margins and intra-oceanic settings. Furthermore, recent work has reignited a debate about the origins of 'anchor' slabs, such as the Farallon and Mongol-Okhotsk slabs, which have been used to refine absolute plate motions. Moving to the mantle, seismic tomography models reveal a region peppered with inferred slabs, however assumptions about their affinities and subduction location, timing, geometry and polarity are often made in isolation. Here, by integrating regional plate reconstructions with insights from seismic tomography, satellite derived gravity gradients, slab sinking rates and geochemistry, I explore some Mesozoic examples from the palaeo-Arctic, northern Panthalassa and western margin of North America, including evidence for a discrete and previously undescribed slab under present-day Greenland. While regional in focus, the methods and insights described have global applications and illustrate the power of an integrated approach.

KSC-2011-2450

NASA Image and Video Library

2011-03-21

VANDENBERG AIR FORCE BASE, Calif. -- The Space Launch Complex-2 (SLC-2) service tower at Vandenberg Air Force Base in California is moved to allow United Launch Alliance technicians to hoist into position the second stage of the Delta II rocket that will carry NASA's Aquarius satellite into low Earth orbit. Scheduled to launch in June, Aquarius' mission will be to provide monthly maps of global changes in sea surface salinity. By measuring ocean salinity from space, Aquarius will provide new insights into how the massive natural exchange of freshwater between the ocean, atmosphere and sea ice influences ocean circulation, weather and climate. Also going up with the satellite are optical and thermal cameras, a microwave radiometer and the SAC-D spacecraft, which were developed with the help of institutions in Italy, France, Canada and Argentina. Photo credit: VAFB/30th Space Wing

KSC-08pd1080

NASA Image and Video Library

2008-04-29

VANDENBERG AIR FORCE BASE, Calif. – After being offloaded from the cargo plane, the shipping container holding the OSTM/Jason-2 satellite is moved away from the plane. The satellite will be taken to the Astrotech processing facility. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Steve Greenberg, JPL

KSC-08pd1082

NASA Image and Video Library

2008-04-29

VANDENBERG AIR FORCE BASE, Calif. – Workers prepare to move the shipping container holding the OSTM/Jason-2 satellite onto a flatbed truck at Vandenberg Air Force Base. The satellite will be transported to the Astrotech processing facility. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Steve Greenberg, JPL

KSC-08pd1282

NASA Image and Video Library

2008-04-29

VANDENBERG AIR FORCE BASE, Calif. -- Workers move the shipping container holding the OSTM/Jason-2 satellite on a flatbed truck at Vandenberg Air Force Base. The satellite will be transported to the Astrotech processing facility. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

KSC-08pd1301

NASA Image and Video Library

2008-04-30

VANDENBERG AIR FORCE BASE, Calif. -- Inside the Astrotech processing facility at Vandenberg Air Force Base, workers attach an overhead crane to the OSTM/Jason-2 spacecraft. The spacecraft will be moved to a tilt dolly. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Mark Mackley

KSC-08pd1281

NASA Image and Video Library

2008-04-29

VANDENBERG AIR FORCE BASE, Calif. -- Workers prepare to move the shipping container holding the OSTM/Jason-2 satellite onto a flatbed truck at Vandenberg Air Force Base. The satellite will be transported to the Astrotech processing facility. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

KSC-08pd1286

NASA Image and Video Library

2008-04-29

VANDENBERG AIR FORCE BASE, Calif. -- At Vandenberg Air Force Base, workers remove the straps holding the OSTM/Jason-2 satellite shipping container on the flatbed truck. The container will be moved inside the Astrotech processing facility at right. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

KSC-08pd1300

NASA Image and Video Library

2008-04-30

VANDENBERG AIR FORCE BASE, Calif. -- Inside the Astrotech processing facility at Vandenberg Air Force Base, an overhead crane is being attached to the OSTM/Jason-2 spacecraft. The spacecraft will be moved to a tilt dolly. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Mark Mackley

KSC-08pd1302

NASA Image and Video Library

2008-04-30

VANDENBERG AIR FORCE BASE, Calif. -- Inside the Astrotech processing facility at Vandenberg Air Force Base, technicians attach an overhead crane to the OSTM/Jason-2 spacecraft. The spacecraft will be moved to a tilt dolly. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Mark Mackley

KSC-08pd1326

NASA Image and Video Library

2008-04-25

VANDENBERG AIR FORCE BASE, Calif. -- On Space Launch Complex 2 at Vandenberg Air Force Base in California, the Delta II first stage for the OSTM/Jason-2 spacecraft is moved into place above the launcher in the umbilical tower. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

Studies of Current Circulation at Ocean Waste Disposal Sites

NASA Technical Reports Server (NTRS)

Klemas, V. (Principal Investigator); Davis, G.; Henry, R.

1976-01-01

The author has identified the following significant results. Acid waste plume was observed in LANDSAT imagery fourteen times ranging from during dump up to 54 hours after dump. Circulation processes at the waste disposal site are highly storm-dominated, with the majority of the water transport occurring during strong northeasterlies. There is a mean flow to the south along shore. This appears to be due to the fact that northeasterly winds produce stronger currents than those driven by southeasterly winds and by the thermohaline circulation. During the warm months (May through October), the ocean at the dump site stratifies with a distinct thermocline observed during all summer cruising at depths ranging from 10 to 21 m. During stratified conditions, the near-bottom currents were small. Surface currents responded to wind conditions resulting in rapid movement of surface drogues on windy days. Mid-depth drogues showed an intermediate behavior, moving more rapidly as wind velocities increased.

Pleading for the use of biodegradable polymers in favor of marine environments and to avoid an asbestos-like problem for the future.

PubMed

Kubota, Masahisa; Takayama, Katsumi; Namimoto, Daisuke

2005-06-01

Research results about the movement and accumulation of floating marine debris drifting throughout the world's oceans are reviewed in this paper. A mechanism for this accumulation and movement is strongly associated with surface currents consisting of the Ekman drift and the geostrophic current, because all floating marine debris is passive to surface currents. The basic published mechanism for the North Pacific is common across the world's ocean. After marine debris accumulates in the narrow Ekman convergence zone, it is moved to the east by geostrophic currents. The most important thing is that floating marine debris concentrates in some specific regions, independent of the initial quantity of marine debris. In order to resolve this problem and to avoid an asbestos-like problem, the use of biodegradable polymers is important in our daily life.

TOPEX/El Nino Watch - Satellite shows El Nino-related Sea Surface Height, Mar, 14, 1998

NASA Technical Reports Server (NTRS)

1998-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Mar. 14, 1998 and sea surface height is an indicator of the heat content of the ocean. The image shows that the sea surface height along the central equatorial Pacific has returned to a near normal state. Oceanographers indicate this is a classic pattern, typical of a mature El Nino condition. Remnants of the El Nino warm water pool, shown in red and white, are situated to the north and south of the equator. These sea surface height measurements have provided scientists with a detailed view of how the 1997-98 El Nino's warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, the National Oceanic and Atmospheric Administration, (NOAA), has continued to issue an advisory indicating the so-called El Nino weather conditions that have impacted much of the United States and the world are expected to remain through the spring.

Effect of a fast-moving tropical storm Washi on phytoplankton in the northwestern South China Sea

NASA Astrophysics Data System (ADS)

Zhao, Hui; Pan, Jiayi; Han, Guoqi; Devlin, Adam T.; Zhang, Shuwen; Hou, Yijun

2017-04-01

Tropical cyclones may augment nutrients in the ocean surface layer through mixing, entrainment, and upwelling, triggering phytoplankton blooms in oligotrophic waters such as the South China Sea (SCS). Previous studies focused mainly on responses of marine environments to strong or slow-moving typhoons in the SCS. In this study, we analyze variations of chlorophyll a (Chl a) and oceanic conditions in the continental shelf region east of Hainan Island during the fast-moving tropical storm Washi and investigate its influences on phytoplankton bloom and related dynamic mechanisms. Results indicate that there was significant variation of Chl a concentration in the continental shelf region, with low values (about 0.1 mg m-3) before the storm and a 30% increase after the storm. This increase was spatially variable, much larger nearshore than offshore. Power spectral analysis of Acoustic Doppler Current Profiler (ADCP) data at a shelf site near the study region reveals strong near-inertial oscillations (NIOs) in the upper layer, with a period of about 36 h, close to the local inertial period. The NIOs intensified mixing and modified the stratification of the upper layer, inducing uplift of nutrients and Chl a into the mixed layer from below, and leading to surface Chl a increase. The relatively shallow nutricline and thermocline in the continental shelf region before the storm were favorable for upwelling of nutrients and generation of NIOs. Advection of nutrients from enhanced runoff during and after the storm may be responsible for the larger increase of the Chl a nearshore.

High Lapse Rates in AIRS Retrieved Temperatures in Cold Air Outbreaks

NASA Technical Reports Server (NTRS)

Fetzer, Eric J.; Kahn, Brian; Olsen, Edward T.; Fishbein, Evan

2004-01-01

The Atmospheric Infrared Sounder (AIRS) experiment, on NASA's Aqua spacecraft, uses a combination of infrared and microwave observations to retrieve cloud and surface properties, plus temperature and water vapor profiles comparable to radiosondes throughout the troposphere, for cloud cover up to 70%. The high spectral resolution of AIRS provides sensitivity to important information about the near-surface atmosphere and underlying surface. A preliminary analysis of AIRS temperature retrievals taken during January 2003 reveals extensive areas of superadiabatic lapse rates in the lowest kilometer of the atmosphere. These areas are found predominantly east of North America over the Gulf Stream, and, off East Asia over the Kuroshio Current. Accompanying the high lapse rates are low air temperatures, large sea-air temperature differences, and low relative humidities. Imagery from a Visible / Near Infrared instrument on the AIRS experiment shows accompanying clouds. These lines of evidence all point to shallow convection in the bottom layer of a cold air mass overlying warm water, with overturning driven by heat flow from ocean to atmosphere. An examination of operational radiosondes at six coastal stations in Japan shows AIRS to be oversensitive to lower tropospheric lapse rates due to systematically warm near-surface air temperatures. The bias in near-surface air temperature is seen to be independent of sea surface temperature, however. AIRS is therefore sensitive to air-sea temperature difference, but with a warm atmospheric bias. A regression fit to radiosondes is used to correct AIRS near-surface retrieved temperatures, and thereby obtain an estimate of the true atmosphere-ocean thermal contrast in five subtropical regions across the north Pacific. Moving eastward, we show a systematic shift in this air-sea temperature differences toward more isothermal conditions. These results, while preliminary, have implications for our understanding of heat flow from ocean to atmosphere. We anticipate future improvements in the AIRS retrieval algorithm will lead to improved understanding of the exchange of sensible and latent heat from ocean to atmosphere, and more realistic near-surface lapse rates.

Idealized Quasi-Linear Convective Storms Crossing Over Coastlines

NASA Astrophysics Data System (ADS)

Lombardo, K.

2015-12-01

As organized coastal convective storms develop over land and move over a coastal ocean, their storm-scale structures, intensity, and associated weather threats evolve. This study aims to identify and quantify the fundamental mechanisms controlling the evolution of coastal quasi-linear convective systems (QLCSs) as they move offshore, as well as characterize the environmental conditions that support a phase space of life cycles. Results from this work will contribute to the improved predictability of these potentially severe warm season storms. The current work uses the Cloud Model 1 (CM1; Bryan and Fritsch 2002) to systematically study the interaction between QLCSs and marine atmospheric boundary layers (MABLs) associated with the coastal ocean in an idealized numerical framework. The initial simulations are run in 2-dimensions, with a 250 m horizontal resolution and a vertical resolution ranging from 100 m in the lowest 3000 m stretched to 250 m at the top of the 20 km domain. All simulations use the Weisman-Klemp analytic sounding as the base-state sounding profile in conjunction with an RKW-type wind profile. To create a numerical environment representative of a coastal region, the western half of the 800 km domain is configured to represent a land surface, while the eastern half represents a water surface. A series of sensitivity experiments are conducted to explore the influence of sea surface temperature and the associated marine atmospheric boundary layer on coastal QLCSs. Sea surface temperature values are selected to represent values observed within the Mid-Atlantic Bight coastal waters during the warm season, ranging from 14oC ('early summer') to 23oC ('late summer'). The numerical MABL is allowed to develop in time through surface heat fluxes. This presentation will discuss preliminary results from the 'early summer' and 'late summer' SST sensitivity experiments. Preliminary simulations indicate that the 'early summer' QLCS moves more quickly than the 'late summer' storm once the systems are over the MABL. Differences in propagation speed will be discussed in the context of lifting mechanisms along the leading edge of the QLCSs. Differences in the intensity of the convection will be discussed as well.

Ocean impact on decadal Atlantic climate variability revealed by sea-level observations.

PubMed

McCarthy, Gerard D; Haigh, Ivan D; Hirschi, Joël J-M; Grist, Jeremy P; Smeed, David A

2015-05-28

Decadal variability is a notable feature of the Atlantic Ocean and the climate of the regions it influences. Prominently, this is manifested in the Atlantic Multidecadal Oscillation (AMO) in sea surface temperatures. Positive (negative) phases of the AMO coincide with warmer (colder) North Atlantic sea surface temperatures. The AMO is linked with decadal climate fluctuations, such as Indian and Sahel rainfall, European summer precipitation, Atlantic hurricanes and variations in global temperatures. It is widely believed that ocean circulation drives the phase changes of the AMO by controlling ocean heat content. However, there are no direct observations of ocean circulation of sufficient length to support this, leading to questions about whether the AMO is controlled from another source. Here we provide observational evidence of the widely hypothesized link between ocean circulation and the AMO. We take a new approach, using sea level along the east coast of the United States to estimate ocean circulation on decadal timescales. We show that ocean circulation responds to the first mode of Atlantic atmospheric forcing, the North Atlantic Oscillation, through circulation changes between the subtropical and subpolar gyres--the intergyre region. These circulation changes affect the decadal evolution of North Atlantic heat content and, consequently, the phases of the AMO. The Atlantic overturning circulation is declining and the AMO is moving to a negative phase. This may offer a brief respite from the persistent rise of global temperatures, but in the coupled system we describe, there are compensating effects. In this case, the negative AMO is associated with a continued acceleration of sea-level rise along the northeast coast of the United States.

Chemical trends in ocean islands explained by plume–slab interaction

NASA Astrophysics Data System (ADS)

Dannberg, Juliane; Gassmöller, Rene

2018-04-01

Earth's surface shows many features, of which the genesis can be understood only through their connection with processes in Earth's deep interior. Recent studies indicate that spatial geochemical patterns at oceanic islands correspond to structures in the lowermost mantle inferred from seismic tomographic models. This suggests that hot, buoyant upwellings can carry chemical heterogeneities from the deep lower mantle toward the surface, providing a window to the composition of the lowermost mantle. The exact nature of this link between surface and deep Earth remains debated and poorly understood. Using computational models, we show that subducted slabs interacting with dense thermochemical piles can trigger the ascent of hot plumes that inherit chemical gradients present in the lowermost mantle. We identify two key factors controlling this process: (i) If slabs induce strong lower-mantle flow toward the edges of these piles where plumes rise, the pile-facing side of the plume preferentially samples material originating from the pile, and bilaterally asymmetric chemical zoning develops. (ii) The composition of the melt produced reflects this bilateral zoning if the overlying plate moves roughly perpendicular to the chemical gradient in the plume conduit. Our results explain some of the observed geochemical trends of oceanic islands and provide insights into how these trends may originate.

Langmuir circulation inhibits near-surface water turbulence

NASA Astrophysics Data System (ADS)

Schultz, Colin

2012-07-01

In the surface ocean, breaking waves are a major source of air bubbles and turbulent kinetic energy. During the presence of a consistent surface wind, these wave-generated bubbles, along with other surface material like seaweed or foam, can be drawn into long rows along the surface. Driving this organization is Langmuir circulation, a phenomenon in which the wind and waves cause surface waters to rotate helically, moving like a wire wrapped around a pole in the windward direction. These spiral currents oscillate between clockwise and counterclockwise rotations, such that in some places the surface waters are pushed together and in others they are pulled apart. Researchers have previously found that at sites of convergence the bubbles produced by breaking waves are pushed to depths of 15 meters or more, with important implications for air-sea gas mixing and other processes.

KSC-2011-2194

NASA Image and Video Library

2011-03-09

VANDENBERG AIR FORCE BASE, Calif. --At Vandenberg Air Force Base in California, one of three United Space Alliance Delta II solid rocket motors is atop a tug for the move from the solid motor facility to Space Launch Complex-2 West (SLC-2W). Scheduled to launch in June, the Delta II rocket will carry NASA's Aquarius satellite into low Earth orbit. Aquarius' mission will be to provide monthly maps of global changes in sea surface salinity. By measuring ocean salinity from space, Aquarius will provide new insights into how the massive natural exchange of freshwater between the ocean, atmosphere and sea ice influences ocean circulation, weather and climate. Also going up with the satellite are optical and thermal cameras, a microwave radiometer and the SAC-D spacecraft, which were developed with the help of institutions in Italy, France, Canada and Argentina. Photo credit: VAFB/30th Space Wing

KSC-2011-2188

NASA Image and Video Library

2011-03-09

VANDENBERG AIR FORCE BASE, Calif. --Before the sun rises over Vandenberg Air Force Base in California, United Launch Alliance technicians prepare to move one of three Delta II solid rocket motors from the solid motor facility to Space Launch Complex-2 West (SLC-2W) atop a tug. ULA technician Eric Chambless is in the tug's driver seat. Scheduled to launch in June, the Delta II rocket will carry NASA's Aquarius satellite into low Earth orbit. Aquarius' mission will be to provide monthly maps of global changes in sea surface salinity. By measuring ocean salinity from space, Aquarius will provide new insights into how the massive natural exchange of freshwater between the ocean, atmosphere and sea ice influences ocean circulation, weather and climate. Also going up with the satellite are optical and thermal cameras, a microwave radiometer and the SAC-D spacecraft, which were developed with the help of institutions in Italy, France, Canada and Argentina. Photo credit: VAFB/30th Space Wing

KSC-08pd1340

NASA Image and Video Library

2008-04-30

VANDENBERG AIR FORCE BASE, Calif. -- On Space Launch Complex 2 at Vandenberg Air Force Base in California, the second solid rocket motor, or SRM, is moved into place alongside the Delta II first stage. The Delta II is the launch vehicle for the OSTM/Jason-2 spacecraft. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

KSC-08pd1333

NASA Image and Video Library

2008-04-30

VANDENBERG AIR FORCE BASE, Calif. -- On Space Launch Complex 2 at Vandenberg Air Force Base in California, a solid rocket motor, or SRM, is lifted alongside the mobile service tower. The SRM will be moved inside the tower and attached to the Delta II first stage, which is the launch vehicle for the OSTM/Jason-2 spacecraft. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

KSC-08pd1325

NASA Image and Video Library

2008-04-25

VANDENBERG AIR FORCE BASE, Calif. -- On Space Launch Complex 2 at Vandenberg Air Force Base in California, the mobile service tower with the Delta II first stage moves closer to the umbilical tower/launcher at right. The Delta II is the launch vehicle for the OSTM/Jason-2 spacecraft. The OSTM, or Ocean Topography Mission, on the Jason-2 satellite is a follow-on to Jason-1. It will take oceanographic studies of sea surface height into an operational mode for continued climate forecasting research and science and industrial applications. This satellite altimetry data will help determine ocean circulation, climate change and sea-level rise. OSTM is a joint effort by the National Oceanic and Atmospheric Administration, NASA, France’s Centre National d’Etudes Spatiales and the European Meteorological Satellite Organisation. OSTM/Jason-2 will be launched aboard a United Launch Alliance Delta II 7320 from Vandenberg on June 15. Photo credit: NASA/Dan Liberotti

Multi-Scale 4DVAR Assimilation of Glider Teams on the North Carolina Shelf

NASA Astrophysics Data System (ADS)

Osborne, J. J. V.; Carrier, M.; Book, J. W.; Barron, C. N.; Rice, A. E.; Rowley, C. D.; Smedstad, L.; Souopgui, I.; Teague, W. J.

2017-12-01

We demonstrate a method to assimilate glider profile data from multiple gliders in close proximity ( 10 km or less). Gliders were deployed in a field experiment from 17 May until 4 June 2017, north of Cape Hatteras and inshore of the Gulf Stream. Gliders were divided into two teams, generally two or three gliders per team. One team was tasked with station keeping and the other with moving and sampling regions of high variability in temperature and salinity. Glider data are assimilated into the Relocatable Navy Coastal Ocean Model (RELO NCOM) with four dimensional variational assimilation (NCOM-4DVAR). RELO NCOM is used by the US Navy to predict the ocean. RELO NCOM is a baroclinic, Boussinesq, free-surface, and hydrostatic ocean model with a flexible sigma-z vertical coordinate. Two domains are used, one focused north and one focused south of Cape Hatteras. The domains overlap near the gliders, thus providing two forecasts near the gliders. Both domains have 1 km horizontal resolution. Data are assimilated in a newly-developed multi-scale data-processing and assimilating approach using NCOM-4DVAR. This enables NCOM-4DVAR to use many more observations than standard NCOM-4DVAR, improving the analysis and forecast. Assimilation experiments use station-keeping glider data, moving glider data, or all glider data. Sea surface temperature (SST) data and satellite altimeter (SSH) data are also assimilated. An additional experiment omits glider data but still assimilates SST and SSH data. Conductivity, temperature, and depth (CTD) profiles from the R/V Savannah are used for validation, including data from an underway CTD (UCTD). Data from glider teams have the potential to significantly improve model forecasts. Missions using teams of gliders can be planned to maximize data assimilation for optimal impact on model predictions.

Physical climatology of Indonesian maritime continent: An outline to comprehend observational studies

NASA Astrophysics Data System (ADS)

Yamanaka, Manabu D.

2016-09-01

The Indonesian maritime continent (IMC) is a miniature of our land-sea coexisting planet Earth. Firstly, without interior activity, the Earth becomes an even-surfaced "aqua-planet" with both atmosphere and ocean flowing almost zonally, and solar differential heating generates (global thermal tides and) Hadley's meridional circulations with the inter-tropical convergence zone (ITCZ) along the equator as observed actually over the open (Indian and Pacific) oceans on the both sides of the IMC. The ITCZ involves intraseasonal variations or super cloud clusters moving eastward with hierarchical substructures moving also westward. Secondly, the lands and seas over the actual Earth have been keeping the area ratio of 3:7 (similar to that of islands and inland/surrounding seas in the IMC), but their displacements have produced the IMC near the equator, which turns equatorial Pacific easterly ocean current northward (Kuroshio) and reflects equatorial oceanic waves that affect coupled ocean-atmosphere interannual variations such as ENSO and IOD, or displacements of Walker's zonal circulations. Thirdly, because the IMC consists of many large/small islands with very long coastlines, many narrow straits control the global (Pacific to Indian) ocean circulation, and the land-sea heat capacity contrasts along the coastlines generate the world's largest rainfall with diurnal cycles (sea-land breeze circulations). The diurnal cycles are dominant even in the rainy season (austral summer in Jawa and Bali), because rainfall-induced sprinkler-like land cooling reverses the trans-coastal temperature gradient before sunrise, and subsequent clear sky on land until around noon provides solar heating dependent on season. These processes lead to rapid land/hydrosphere-atmosphere water exchange, local air pollutant washout, and transequatorial boreal winter monsoon (cold surge). In El Niño years, for example, the cooler sea-surface temperature suppresses the morning coastal-sea rainfall, and induces often serious smog diffused from land over the IMC. Lastly, high-resolution observations/models covering both over islands and seas are necessary. A radar-profiler network (HARIMAU) has been constructed during FY2005-09, and capacity building on radar operations and buoy manufacturing has been promoted during FY2009-13 by Japan-Indonesia collaboration projects, which are taken over by an Indonesian national center (MCCOE) established in November 2013. Through these projects, variabilities of local circulations and precipitations with diurnal cycles have been recognized as important targets both in science and application.

The Stability of Outcropping Ocean Eddies

NASA Astrophysics Data System (ADS)

Paldor, N.; Cohen, Y.; Dvorkin, Y.

2017-12-01

In the end of the last century numerous ship-borne observations and linear instability studies have addressed the long life span of meso-scale ocean eddies. These eddies are observed to persist in the ocean for periods of 2-3 years with little deformation. As eddy instabilities occur because Rossby waves in the surrounding (assumed motionless) ocean interact with various waves in the eddy itself, the stability was attributed to some eddy structure that hinders such wave-wave interactions. However, instabilities with growthrates of the order of the inertial period were found in various multilayer models including hypothesized structures and several observed eddy structures. A solution to the difference between instability theory and observed stability was ultimately suggested by relaxing the assumption of a motionless ocean that surrounds the eddy and prescribing the mean flow in the ocean such that it counterbalances the depth changes imposed by the eddy while maintaining a constant PV-ocean. This hypothesis was successfully applied to Gaussian eddies for mathematical simplicity. Yet, the Gaussian eddy has no surface front - thus avoiding instabilities that involve frontal waves - and it disagrees with observation that clearly show that most eddies have surface fronts. Here the constant PV ocean hypothesis is applied to two frontal eddies: constant PV-eddies and solidly rotating eddy. A complete account of the mean flow of the coupled eddy-ocean system is analyzed using a canonical formulation of the gradient balance. The phase speeds of waves in the eddy-ocean system are computed by a shooting method. Both eddies are found to be unstable in motionless ocean, yet in a constant PV-ocean no instabilities are found using the exact same numerical search. While many eddy structures can be hypothesized there are only a handful of physical mechanisms for instability and in these eddies the assumed constant PV-ocean negates many of these physical mechanisms for instability. This implies that meso-scale eddies should be stable in a constant PV ocean, regardless to their structure, which is not precisely one of the above mentioned. This theory stimulates observations of the ocean under the eddies. To maintain the uniform PV value, relative vorticity must develop in the ocean under the eddy as it moves in the ocean.

The Sea Around Us

NASA Astrophysics Data System (ADS)

Carson, Rachel L.

1991-12-01

Published in 1951, The Sea Around Us is one of the most remarkably successful books ever written about the natural world. Rachel Carson's rare ability to combine scientific insight with moving, poetic prose catapulted her book to first place on The New York Times best-seller list, where it enjoyed wide attention for thirty-one consecutive weeks. It remained on the list for more than a year and a half and ultimately sold well over a million copies, has been translated into 28 languages, inspired an Academy Award-winning documentary, and won both the 1952 National Book Award and the John Burroughs Medal. This classic work remains as fresh today as when it first appeared. Carson's writing teems with stunning, memorable images--the newly formed Earth cooling beneath an endlessly overcast sky; the centuries of nonstop rain that created the oceans; giant squids battling sperm whales hundreds of fathoms below the surface; and incredibly powerful tides moving 100 billion tons of water daily in the Bay of Fundy. Quite simply, she captures the mystery and allure of the ocean with a compelling blend of imagination and expertise. Reintroducing a classic work to a whole new generation of readers, this Special Edition features a new chapter written by Jeffrey Levinton, a leading expert in marine ecology, that brings the scientific side of The Sea Around Us completely up to date. Levinton incorporates the most recent thinking on continental drift, coral reefs, the spread of the ocean floor, the deterioration of the oceans, mass extinction of sea life, and many other topics. In addition, acclaimed nature writer Ann Zwinger has contributed a brief foreword. Today, with the oceans endangered by the dumping of medical waste and ecological disasters such as the Exxon oil spill in Alaska, this illuminating volume provides a timely reminder of both the fragility and the importance of the ocean and the life that abounds within it. Anyone who loves the sea, or who is concerned about our natural environment, will want to read this classic work.

The Intense Arctic Cyclone of Early August 2012: A Dynamically Driven Cyclogenesis Event

NASA Astrophysics Data System (ADS)

Bosart, L. F.; Turchioe, A.; Adamchcik, E.

2013-12-01

A series of surface cyclones formed along an anomalously strong northeast-southwest oriented baroclinic zone over north-central Russia on 1-3 August 2012. These cyclones moved northeastward, intensified slowly, and crossed the coast of Russia by 4 August. The last cyclone in the series strengthened rapidly as it moved poleward over the Arctic Ocean on 5-6 August, achieved a minimum sea level pressure of < 965 hPa by 6 August, and was arguably the most intense storm system to impact the Arctic Ocean in the modern data record going back to the International Geophysical Year in 1957-1958. The purpose of this presentation is to illustrate the structure and life cycle of this Arctic Ocean cyclone from a multiscale perspective. Anticyclonic wave breaking in the upper troposphere across Russia in late July and very early August 2012 created an anomalously strong baroclinic zone across northern Asia between 60-80°N. During 1-5 August, negative 850 hPa temperature anomalies between -2° and -4°C were found poleward of 70-75°N between 90°E and the Dateline over the Arctic Ocean while positive 850 hPa temperature anomalies of 8-9°C were found over eastern Russia near 60°N. The associated anomalously strong 850 hPa meridional temperature gradient of ~10°C (2000 km)-1 helped to sustain an anomalously strong (20-30 m s-1) 250 hPa jet along the coast of northeastern Russia. A local wind speed maximum (~50 m s-1 ) embedded in this 250 hPa jet corridor contributed to the extreme intensity of the trailing (last) surface cyclone in the series. Although the dominant surface cyclone in the series of surface cyclones intensified most rapidly over the relatively ice free Arctic Ocean, the impact of surface heat and moisture fluxes appeared to be secondary to jet-driven dynamical processes in the deepening process. Anomalously high observed 1000-500 hPa thickness values between 564-570 dam, precipitable water values between 30-40 mm, and CAPE values between 500-1000 J kg-1 in the warm sector of the developing cyclone over north-central Russia were indicative of the enhanced baroclinicity and instability in the cyclone warm sector and the ability of lower tropospheric warm-air advection to sustain deep ascent in the intensifying cyclone. The relative importance of dynamical versus thermodynamical forcing to the cyclogenesis process as well as the bulk upscale effects of the intense cyclone on the larger scale higher-latitude circulation and the distribution of sea ice will be discussed. A noteworthy aspect of the post-storm polar environment was the upscale growth of a midlevel cyclonic circulation to include most of the Arctic Ocean. The off-pole displacement of this midlevel cyclonic circulation toward northern Canada by mid-August may have contributed to the termination of the 2012 summer-long intensive heat wave over most of the continental United States.

An Assessment of the Potential Impacts on Zooplankton and Fish of Ocean Dredged Material at the Norfolk Disposal Site.

DTIC Science & Technology

1984-09-07

McConaugha et al., 1983). This retention mechanism is entirely dependent upon southerly winds of sufficient magnitude to drive a northward current. Since the...Chesapeake Bay Inflow Streamline Patterns for Periods of Northerly (Figure 6a) and Southerly (Figure 6b) Winds ..... ...... .... 2-2 7 Surface Salinity ...layer flow: Low salinity water from rivers and other fresh water inputs moves seaward in the upper layer, while high salinity shelf water is drawn into

Ocean Wave Energy Harvesting Devices

DTIC Science & Technology

2007-04-01

the magnet stack and the tubular wall of the generator and completely prevent the magnet from making direct contact to the tube wall even when the...the 3.1 second device. If no ferrofluid is present, as a long magnetic stack moves inside a tube with a small gap between the magnet surface and the...inside wall of the tube , a very slight deviation from the vertical position can cause the edge of the end of the magnet stack to touch the tube (Fig. 3

TOPEX/El Nino Watch - Warm Water Pool is Thinning, Feb, 5, 1998

NASA Technical Reports Server (NTRS)

1998-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Feb. 5, 1998 and sea surface height is an indicator of the heat content of the ocean. The area and volume of the El Nino warm water pool that is affecting global weather patterns remains extremely large, but the pool has thinned along the equator and near the coast of South America. This 'thinning' means that the warm water is not as deep as it was a few months ago. Oceanographers indicate this is a classic pattern, typical of a mature El Nino condition that they would expect to see during the ocean's gradual transition back to normal sea level. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, the National Oceanic and Atmospheric Administration, (NOAA), has continued to issue an advisory indicating the so-called El Nino weather conditions that have impacted much of the United States and the world are expected to remain through the spring.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov

The observation of ocean surface phenomena using imagery from the SEASAT synthetic aperture radar: An assessment

NASA Astrophysics Data System (ADS)

Vesecky, John F.; Stewart, Robert H.

1982-04-01

Over the period July 4 to October 10, 1978, the SEASAT synthetic aperture radar (SAR) gathered 23 cm wavelength radar images of some 108 km2 of the earth's surface, mainly of ocean areas, at 25-40 m resolution. Our assessment is in terms of oceanographic and ocean monitoring objectives and is directed toward discovering the proper role of SAR imagery in these areas of interest. In general, SAR appears to have two major and somewhat overlapping roles: first, quantitative measurement of ocean phenomena, like long gravity waves and wind fields, as well as measurement of ships; second, exploratory observations of large-scale ocean phenomena, such as the Gulf Stream and its eddies, internal waves, and ocean fronts. These roles are greatly enhanced by the ability of 23 cm SAR to operate day or night and through clouds. To begin we review some basics of synthetic aperture radar and its implementation on the SEASAT spacecraft. SEASAT SAR imagery of the ocean is fundamentally a map of the radar scattering characteristics of ˜30 cm wavelength ocean waves, distorted in some cases by ocean surface motion. We discuss how wind stress, surface currents, long gravity waves, and surface films modulate the scattering properties of these resonant waves with particular emphasis on the mechanisms that could produce images of long gravity waves. Doppler effects by ocean motion are also briefly described. Measurements of long (wavelength ≳100 m) gravity waves, using SEASAT SAR imagery, are compared with surface measurements during several experiments. Combining these results we find that dominant wavelength and direction are measured by SEASAT SAR within ±12% and ±15°, respectively. However, we note that ocean waves are not always visible in SAR images and discuss detection criteria in terms of wave height, length, and direction. SAR estimates of omnidirectional wave height spectra made by assuming that SAR image intensity is proportional to surface height fluctuations are more similar to corresponding surface measurements of wave height spectra than to wave slope spectra. Because SEASAT SAR images show the radar cross section σ° of ˜30 cm waves (neglecting doppler effects), and because these waves are raised by wind stress on the ocean surface, wind measurements are possible. Comparison between wind speeds estimated from SEASAT SAR imagery and from the SEASAT satellite scatterometer (SASS) agreed to within ±0.7 m s- over a 350-km comparison track and for wind speeds from 2 to 15 m s-. The great potential of SAR wind measurements lies in studying the spatial structure of the wind field over a range of spatial scales of from ≲1 km to ≳100 km. At present, the spatial and temporal structure of ocean wind fields is largely unknown. Because SAR responds to short waves whose energy density is a function of wind stress at the surface rather than wind speed at some distance above the surface, variations in image intensity may also reflect changes in air-sea temperature difference (thus complicating wind measurements by SAR). Because SAR images show the effects of surface current shear, air-sea temperature difference, and surface films through their modulation of the ˜30 cm waves, SEASAT images can be used to locate and study the Gulf Stream and related warm water rings, tidal flows at inlets, internal waves, and slicks resulting from surface films. In many of these applications, SAR provides a remote sensing capability that is complementary to infrared imagery because the two techniques sense largely different properties, namely, surface roughness and temperature. Both stationary ships and moving ships with their attendant wakes are often seen in SAR images. Ship images can be used to estimate ship size, heading, and speed. However, ships known to be in areas imaged by SAR are not always detectable. Clearly, a variety of factors, such as image resolution, ship size, sea state, and winds could affect ship detection. Overall, the role of SAR imagery in oceanography is definitely evolving at this time, but its ultimate role is unclear. We have assessed the ability of SEASAT SAR to measure a variety of ocean phenomena and have commented briefly on applications. In the end, oceanographers and others will have to judge from these capabilities the proper place for SAR in oceanography and remote sensing of the ocean.

TOPEX/El Nino Watch - El Nino Warm Water Pool Returns to Near Normal State, Mar, 14, 1998

NASA Technical Reports Server (NTRS)

1998-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Mar. 14, 1998 and sea surface height is an indicator of the heat content of the ocean. The image shows that the sea surface height along the central equatorial Pacific has returned to a near normal state. Oceanographers indicate this is a classic pattern, typical of a mature El Nino condition. Remnants of the El Nino warm water pool, shown in red and white, are situated to the north and south of the equator. These sea surface height measurements have provided scientists with a detailed view of how the 1997-98 El Nino's warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using satellite imagery, buoy and ship data, and a forecasting model of the ocean-atmosphere system, the National Oceanic and Atmospheric Administration, (NOAA), has continued to issue an advisory indicating the so-called El Nino weather conditions that have impacted much of the United States and the world are expected to remain through the spring.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov

TOPEX/El Nino Watch - Warm Water Pool is Increasing, Nov. 10, 1997

NASA Technical Reports Server (NTRS)

1997-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Nov. 10, 1997. The volume of extra warm surface water (shown in white) in the core of the El Nino continues to increase, especially in the area between 15 degrees south latitude and 15 degrees north latitude in the eastern Pacific Ocean. The area of low sea level (shown in purple) has decreased somewhat from late October. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 centimeters and 32 cm (6 inches to 13 inches) above normal; in the red areas, it is about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one-and-one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21 to 30 degrees Celsius (70 to 85 degrees Fahrenheit), is about 30 times the volume of water in all the U.S. Great Lakes combined. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white areas) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmospheric system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration (NOAA) has issued an advisory indicating the presence of a strong El Nino condition throughout the winter.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov/

A seasonal forecast scheme for the Inner Mongolia spring drought - Part-I: dynamic characteristics of the atmospheric circulation and forecast signals

NASA Astrophysics Data System (ADS)

Gao, Tao; Si, Yaobing; Yu, Xiao; Wulan; Yang, Peng; Gao, Jing

2018-02-01

This study analyzed the atmospheric evolutionary characteristics of insufficient rainfall that leads to spring drought in Inner Mongolia, China. The results revealed that a weakened western Pacific subtropical high and an enlarged North Polar vortex with a western position of the East Asian trough generally result in unfavorable moisture transportation for spring precipitation in IM. It was found that an abnormal sea surface temperature in several crucial ocean areas triggers an irregular atmospheric circulation over the Eurasian continent and the Pacific region. Lower sea surface temperature (SST) during the previous autumn over tropical regions of the central-eastern Pacific and Indian oceans induce a strong Walker circulation, corresponding to a weak and southeastward-retreating subtropical high over the western Pacific during the following winter and spring. Another crucial area is the central region of the North Atlantic Ocean. Abnormally low SST of the ocean area during the preceding autumn causes the Scandinavian teleconnection pattern (the index of which is issued on the website of the Climate Prediction Center, USA) changes to a positive phase, which leads to a weak westerly over the Eurasian continent. In this case, the easterly over the North Pole becomes stronger than normal, resulting in an extended North Polar vortex during the following spring. In addition, SST differences during the previous December between the middle-eastern tropical and the northwestern regions of the Pacific Ocean reflect variations of the Pacific Decadal Oscillation, causing the East Asian trough to move to a western position during the following spring.

The Ocean Surface Topography Mission (OSTM)

NASA Astrophysics Data System (ADS)

Neeck, Steven P.; Vaze, Parag V.

2008-10-01

The Ocean Surface Topography Mission (OSTM), also known as Jason-2, will extend into the next decade the continuous climate data record of sea surface height measurements begun in 1992 by the joint NASA/Centre National d'Etudes Spatiales (CNES) TOPEX/Poseidon mission and continued by the NASA/CNES Jason-1 mission in 2001. This multi-decadal record has already helped scientists study the issue of global sea level rise and better understand how ocean circulation and climate change are related. With OSTM, high-precision ocean altimetry has come of age. The mission will serve as a bridge to transition the collection of these measurements to the world's weather and climate forecasting agencies. The agencies will use them for short- and seasonal-to-long-range weather and climate forecasting. OSTM is designed to last at least three years. It will be placed in the same orbit (1,336 kilometers) as Jason-1 and will move along the same ground track at an inclination of 66 degrees to the equator. It will repeat its ground track every 10 days, covering 95 percent of the world's ice-free oceans. A tandem mission between Jason-1 and OSTM will be conducted to further improve tide models in coastal and shallow seas, and to better understand the dynamics of ocean currents and eddies. OSTM is an international and interagency mission developed and operated as a four-party collaboration among NASA, the National Oceanic and Atmospheric Administration (NOAA), CNES, and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). CNES is providing the spacecraft, NASA and CNES are jointly providing the payload instruments and NASA is providing the launch vehicle. After completing the onorbit commissioning of the spacecraft, CNES will hand over operation and control of the spacecraft to NOAA. NOAA and EUMETSAT will generate the near-real-time products and distribute them to users. OSTM was launched from Vandenberg Air Force Base, California on June 20, 2008. Launch and Early Orbit Operations (LEOP) and the on-orbit Assessment Phase have been completed. Preliminary science data show excellent performance.

Experiment Evaluation of Skin Friction Drag by Surface Tailoring

NASA Astrophysics Data System (ADS)

Manigandan, S.; Gopal krishna, K.; Gagan Kumar, K.; Gunasekar, P.; Nithya, S.

2017-08-01

Reduction of drag is an important role of aerodynamic specialist in real time world. The performance of forward moving object improved when the drag is reduced. Skin friction drag caused when the fluid tending to shear along the surface of the body and it is dependent on energy expenditure. Initial research concluded that nearly 20 to 40% of total drag is skin friction drag, based on flight forward velocity. This means a lot of fuel burned. In this paper we investigate a methodology to reduce the skin friction drag by implementing different kinds of exterior treatments. The ideology inspired from the world fastest moving oceanic creature. Structures are fabricated based on the replica of scales of the oceanic creature. The outer skin of the aerofoil NACA0012 is modified like shark scales. Then it is tested using open type sub sonic wind tunnel. In addition to that, the leading edge thickness effect also studied. The turbulent flow phenomenon is validated at different velocities and compared with numerical results using STAR CCM+. From the plots and graphical results, it is found that the skin friction drag is generated less due to reduction of transverse shear stress present in turbulent flow and skin friction drag depends on boundary layer thickness and on the percentage of chord of flow separation. In addition to this, the result delivers that the ordinary polished surface produces more drag than the modified scales. The outlook of this technology is excrescence for different applications. This open section wind tunnel testing produces 10-15% reduction in drag and can be turn to high values when the experiment is conducted in closed section wind tunnel with real time atmospheric conditions, which can be done as a future work.

Annual Cycle of Cloud Forcing of Surface Radiation Budget

NASA Technical Reports Server (NTRS)

Wilber, Anne C.; Smith, G. Louis; Stackhouse, Paul W., Jr.; Gupta, Shashi K.

2006-01-01

The climate of the Earth is determined by its balance of radiation. The incoming and outgoing radiation fluxes are strongly modulated by clouds, which are not well understood. The Earth Radiation Budget Experiment (Barkstrom and Smith, 1986) provided data from which the effects of clouds on radiation at the top of the atmosphere (TOA) could be computed (Ramanathan, 1987). At TOA, clouds increase the reflected solar radiation, tending to cool the planet, and decrease the OLR, causing the planet to retain its heat (Ramanathan et al., 1989; Harrison et al., 1990). The effects of clouds on radiation fluxes are denoted cloud forcing. These shortwave and longwave forcings counter each other to various degrees, so that in the tropics the result is a near balance. Over mid and polar latitude oceans, cloud forcing at TOA results in large net loss of radiation. Here, there are large areas of stratus clouds and cloud systems associated with storms. These systems are sensitive to surface temperatures and vary strongly with the annual cycle. During winter, anticyclones form over the continents and move to the oceans during summer. This movement of major cloud systems causes large changes of surface radiation, which in turn drives the surface temperature and sensible and latent heat released to the atmosphere.

Influence of air-sea coupling on Indian Ocean tropical cyclones

NASA Astrophysics Data System (ADS)

Lengaigne, Matthieu; Neetu, S.; Samson, Guillaume; Vialard, Jérôme; Krishnamohan, K. S.; Masson, Sébastien; Jullien, Swen; Suresh, I.; Menkes, Christophe E.

2018-02-01

This paper assesses the impact of air-sea coupling on Indian Ocean tropical cyclones (TCs) by comparing a 20-year long simulation of a ¼° regional coupled ocean-atmosphere model with a twin experiment, where the atmospheric component is forced by sea surface temperature from the coupled simulation. The coupled simulation reproduces the observed spatio-temporal TCs distribution and TC-induced surface cooling reasonably well, but overestimates the number of TCs. Air-sea coupling does not affect the cyclogenesis spatial distribution but reduces the number of TCs by 20% and yields a better-resolved bimodal seasonal distribution in the northern hemisphere. Coupling also affects intensity distribution, inducing a four-fold decrease in the proportion of intense TCs (Cat-2 and stronger). Air-sea coupling damps TCs growth through a reduction of inner-core upward enthalpy fluxes due to the TC-induced cooling. This reduction is particularly large for the most intense TCs of the northern Indian Ocean (up to 250 W m-2), due to higher ambient surface temperatures and larger TC-induced cooling there. The negative feedback of air-sea coupling on strongest TCs is mainly associated with slow-moving storms, which spend more time over the cold wake they induce. Sensitivity experiments using a different convective parameterization yield qualitatively similar results, with a larger ( 65%) reduction in the number of TCs. Because of their relatively coarse resolution (¼°), both set of experiments however fail to reproduce the most intense observed TCs. Further studies with finer resolution models in the Bay of Bengal will be needed to assess the expectedly large impact of air-sea coupling on those intense and deadly TCs.

Small Moves, NUI. Small Moves: Beginning to Investigate Biogeochemical Exchange From the Seafloor to the Exterior of an Ice-Covered Ocean

NASA Astrophysics Data System (ADS)

German, C. R.; Boetius, A.

2017-12-01

We present results from two recent cruises, using the new Nereid Under Ice (NUI) vehicle aboard the FS Polarstern, in which we investigated biogeochemical fluxes from the deep seafloor of the Gakkel Ridge, an ultraslow spreading ridge that spans the ice-covered Arctic Ocean, and the mechanisms by which biogeochemical signals might be transferred from within the underlying ocean to the overlying Arctic ice. The scientific advances for this work progress hand in hand with technological capability. During a first cruise in 2014, our NUI-based investigations focused on photosynthetically-driven biogeochemical cycling in the uppermost water column and how to study such processes using in situ sensing immediately at and beneath the rough topography of the overlying ice-cover. For that work we relied entirely upon human-in-the-loop control of the vehicle via a single optical fiber light tether than provided real-time monitoring and control of the vehicle as it ranged laterally out under the ice up to 1km distant from the ship, conducting physical, geochemical and biological surveys. Instrumentation used for that work included multibeam mapping and imaging (digital still photographs and HD video), in situ spectroscopy to study light transmission through the ice and biogeochemical mapping of the ocean water column using a combination of CTD sensing, fluorometry and an in situ nitrate analyzer. Returning to the Arctic in 2016 we extended our exploration modes with NUI further, investigating for seafloor fluid flow at a shallow setting on the flanks of the Gakkel Ridge where the seabed rises from >4000m to <600m depth. In AUV mode, NUI conducted water column sensing using CTD, optical backscatter and Eh sensors and seafloor surveys using high resolution multibeam bathymetry and stereoscopic seafloor imaging. In subsequent ROV operations, NUI was used to conduct detailed investigation of seabed biological communities. This included targeted sampling of individual organisms and ecosystems at precise locations at the seabed completely decoupled from the movement of the ship (horizontal displacements of 1km or more) at the ice-covered ocean surface. While the existing NUI vehicle does not map directly to model payloads for future SLS missions to Europa or Enceladus it does provide for important small moves in the right direction.

Potential of Future Hurricane Imaging Radiometer (HIRAD) Ocean Surface Wind Observations for Determining Tropical Storm Vortex Intensity and Structure

NASA Technical Reports Server (NTRS)

Atlas, Robert; Bailey, M. C.; Black, Peter; James, Mark; Johnson, James; Jones, Linwood; Miller, Timothy; Ruf, Christopher; Uhlhorn, Eric

2008-01-01

The Hurricane Imaging Radiometer (HIRAD) is an innovative technology development, which offers the potential of new and unique remotely sensed observations of both extreme oceanic wind events and strong precipitation from either UAS or satellite platforms. It is based on the airborne Stepped Frequency Microwave Radiometer (SFMR), which is a proven aircraft remote sensing technique for observing tropical cyclone ocean surface wind speeds and rain rates, including those of major hurricane intensity. The proposed HIRAD instrument advances beyond the current nadir viewing SFMR to an equivalent wide-swath SFMR imager using passive microwave synthetic thinned aperture radiometer technology. This sensor will operate over 4-7 GHz (C-band frequencies) where the required tropical cyclone remote sensing physics has been validated by both SFMR and WindSat radiometers. HIRAD incorporates a unique, technologically advanced array antenna and several other technologies successfully demonstrated by the NASA's Instrument Incubator Program. A brassboard version of the instrument is complete and has been successfully tested in an anechoic chamber, and development of the aircraft instrument is well underway. HIRAD will be a compact, lightweight, low-power instrument with no moving parts that will produce wide-swath imagery of ocean vector winds and rain during hurricane conditions when existing microwave sensors (radiometers or scatterometers) are hindered. Preliminary studies show that HIRAD will have a significant positive impact on analyses as either a new aircraft or satellite sensor.

The Continuation of Cloud Statistics for NASA Climate Change Studies

NASA Technical Reports Server (NTRS)

Wylie, Donald P.

2001-01-01

The weather systems, cyclones, and anticyclones, along with air trajectories and cloud forms, are compared to past studies of the Arctic to assess compatibility of the four month study of the Arctic Cloud Experiment flights of the First ISCCP Regional Experiment (FIRE/ACE) with past climatologies. The frequency and movement of cyclones (lows) and anticyclones (highs) followed the general eastward and northeastward directions indicated by past studies. Most cyclones (lows) came from eastern Siberia and the Bering Sea to the south and moved north across the Bering Straight or Alaska into the Arctic Ocean. They generally weakened in central pressure as they moved poleward. Anticyclones (highs) were most common in the eastern Beaufort Sea near Canada in June and July as predicted from previous studies. However, many cyclones and anticyclones moved in westward directions which is rare in other latitudes. Erratic changes in shape and intensity on a daily basis also were observed. The National Center for Environmental Prediction (NCEP) analysis generally reflected the Surface Heat Budget in the Arctic (SHEBA) Ship World Meteorological Organization (WMO) observations which it used. However, NCEP temperatures were biased warm by 1.0 to 1.5 C in April and early May. In July when the surface temperature were at the freezing/thawing point, the NCEP analysis changed to a cold bias of -1.0 C. Dew points had smaller biases except for July where they were biased cold by -1.4 C. Wind speeds had a -2 m/s low bias for the six windiest days. Surface barometric pressures had consistently low biases from -1.2 to -2.8 hPa in all four months. Air parcel historical trajectories were mainly from the south or from local anticyclonic gyres in the Beaufort Sea. Most air came to the SHEBA Ship from the north Pacific Ocean or from Alaska and Canada and occasionally from eastern Siberia. Very few trajectories traced back across the pole to Europe and Central Asia. Cloud cover was high, as expected, from 69-86% of the time. Satellite data also indicate frequent stratus, altostratus, and cirrus clouds (occurring 61% of the time) above the expected boundary layer fog and Arctic stratus clouds.

Broadening our View of the MOC using Satellite Altimetry and Two Moored Arrays in the Atlantic: MOVE 16N and RAPID 26N

NASA Astrophysics Data System (ADS)

Duchez, A.; Frajka-Williams, E.; Lankhorst, M. J.; Koelling, J.; Send, U.

2016-02-01

The Atlantic meridional overturning circulation (MOC) carries heat northwards in the top 1000m of the Atlantic, with a deep, cold return flow below. Climate simulations predict a slowing of the AMOC in the coming years, while present day observations from boundary arrays demonstrate substantial variability on weekly- to interannual timescales. Using simultaneous observations from the MOVE 16N and RAPID 26N arrays in the Atlantic, we investigate transport and property variability. On long timescales, the tendencies in deep densities are similar between the two latitudes (towards lighter water in the west), resulting in a change in the thermal wind balance across the Atlantic. This tendency is punctuated by a more abrupt change in late 2009 at 26N and 7 months later at 16N. In situ arrays such as RAPID 26N and MOVE 16N provide detailed depth structure of transport variability, but are necessarily limited to individual latitudes. Using satellite altimetry, we show that the sea surface height (SSH) anomalies in the western half of the Atlantic covary with in situ transport estimates on interannual timescales. We use satellite altimetry to extend estimates of depth-integrated ocean transports back in time to 1993, then investigate how the spatial pattern of SSH variability broadens our view of Atlantic MOC structure beyond individual latitudes. This analysis investigates two decade+ long time series of ocean transports, and complements the findings with satellite observations.

First satellite tracks of South Atlantic sea turtle ‘lost years’: seasonal variation in trans-equatorial movement

PubMed Central

Mendilaharsu, Milagros L.; dei Marcovaldi, Maria A. G.; Sacco, Alexander E.; Lopez, Gustave; Pires, Thais; Swimmer, Yonat

2017-01-01

In the South Atlantic Ocean, few data exist regarding the dispersal of young oceanic sea turtles. We characterized the movements of laboratory-reared yearling loggerhead turtles from Brazilian rookeries using novel telemetry techniques, testing for differences in dispersal during different periods of the sea turtle hatching season that correspond to seasonal changes in ocean currents. Oceanographic drifters deployed alongside satellite-tagged turtles allowed us to explore the mechanisms of dispersal (passive drift or active swimming). Early in the hatching season turtles transited south with strong southward currents. Late in the hatching season, when currents flowed in the opposite direction, turtles uniformly moved northwards across the Equator. However, the movement of individuals differed from what was predicted by surface currents alone. Swimming velocity inferred from track data and an ocean circulation model strongly suggest that turtles' swimming plays a role in maintaining their position within frontal zones seaward of the continental shelf. The long nesting season of adults and behaviour of post-hatchlings exposes young turtles to seasonally varying ocean conditions that lead some individuals further into the South Atlantic and others into the Northern Hemisphere. Such migratory route diversity may ultimately buffer the population against environmental changes or anthropologic threats, fostering population resiliency. PMID:29212722

Global plate motion frames: Toward a unified model

NASA Astrophysics Data System (ADS)

Torsvik, Trond H.; Müller, R. Dietmar; van der Voo, Rob; Steinberger, Bernhard; Gaina, Carmen

2008-09-01

Plate tectonics constitutes our primary framework for understanding how the Earth works over geological timescales. High-resolution mapping of relative plate motions based on marine geophysical data has followed the discovery of geomagnetic reversals, mid-ocean ridges, transform faults, and seafloor spreading, cementing the plate tectonic paradigm. However, so-called "absolute plate motions," describing how the fragments of the outer shell of the Earth have moved relative to a reference system such as the Earth's mantle, are still poorly understood. Accurate absolute plate motion models are essential surface boundary conditions for mantle convection models as well as for understanding past ocean circulation and climate as continent-ocean distributions change with time. A fundamental problem with deciphering absolute plate motions is that the Earth's rotation axis and the averaged magnetic dipole axis are not necessarily fixed to the mantle reference system. Absolute plate motion models based on volcanic hot spot tracks are largely confined to the last 130 Ma and ideally would require knowledge about the motions within the convecting mantle. In contrast, models based on paleomagnetic data reflect plate motion relative to the magnetic dipole axis for most of Earth's history but cannot provide paleolongitudes because of the axial symmetry of the Earth's magnetic dipole field. We analyze four different reference frames (paleomagnetic, African fixed hot spot, African moving hot spot, and global moving hot spot), discuss their uncertainties, and develop a unifying approach for connecting a hot spot track system and a paleomagnetic absolute plate reference system into a "hybrid" model for the time period from the assembly of Pangea (˜320 Ma) to the present. For the last 100 Ma we use a moving hot spot reference frame that takes mantle convection into account, and we connect this to a pre-100 Ma global paleomagnetic frame adjusted 5° in longitude to smooth the reference frame transition. Using plate driving force arguments and the mapping of reconstructed large igneous provinces to core-mantle boundary topography, we argue that continental paleolongitudes can be constrained with reasonable confidence.

The Role and Variability of Ocean Heat Content in the Arctic Ocean: 1948-2009

DTIC Science & Technology

2014-06-01

moved from the Bering Sea past the Bering Strait into the Beaufort Sea (Logerwell 2008). However, besides the risks of ocean acidification and...VARIABILITY OF OCEAN HEAT CONTENT IN THE ARCTIC OCEAN : 1948–2009 by Dominic F. DiMaggio June 2014 Thesis Co-Advisors: Wieslaw Maslowski...COVERED Master’s Thesis 4. TITLE AND SUBTITLE THE ROLE AND VARIABILITY OF OCEAN HEAT CONTENT IN THE ARCTIC OCEAN : 1948–2009 5. FUNDING NUMBERS 6

TOPEX/El Nino Watch - October 3, 1997

NASA Technical Reports Server (NTRS)

1997-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Oct. 3, 1997 as the warm water associated with El Nino (in white) spreads northward along the entire coast of North America from the equator all the way to Alaska. The warm water pool in tropical Pacific resulting from El Nino seems to have stabilized. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one and one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21 and 30 C (70 to 85 F), carries the amount of heat equal to 100 times the amount of fossil fuel energy consumed by the entire U.S. population during one year. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration (NOAA) has issued an advisory indicating the presence of a strong El Nino condition throughout the coming winter.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov/

Seabird drift as a proxy to estimate surface currents in the western Mediterranean?

NASA Astrophysics Data System (ADS)

Gomez-Navarro, Laura; Sánchez-Román, Antonio; Pascual, Ananda; Fablet, Ronan; Hernandez-Carrasco, Ismael; Mason, Evan; Arcos, José Manuel; Oro, Daniel

2017-04-01

Seabird trajectories can be used as proxies to investigate the dynamics of marine systems and their spatiotemporal evolution. Previous studies have mainly been based on analyses of long range flights, where birds are travelling at high velocities over long time periods. Such data have been used to study wind patterns, and areas of avian feeding and foraging have also been used to study oceanic fronts. Here we focus on "slow moving" periods (which we associate to when birds appear to be drifting on the sea surface), in order to investigate bird drift as a proxy for sea surface currents in the western Mediterranean Sea. We analyse trajectories corresponding to "slow moving" periods recorded by GPSs attached to individuals of the species Calonectris diomedea ( Scopoli's shearwater) from mid August to mid September 2012. The trajectories are compared with sea level anomaly (SLA), sea surface temperature (SST), Finite Size Lyapunov Exponents (FSLE), wind fields, and the outputs from an automated sea-surface-height based eddy tracker. The SLA and SST datasets were obtained from the Copernicus Marine Environment Monitoring Service (CMEMS) with a spatial resolution of 1/8 ̊ and 1/100 ̊ respectively while the FSLEs were computed from the SLA dataset. Finally, the wind data comes from the outputs of the CCMPv2 numerical model. This model has a global coverage with a spatial resolution of 1/4 ̊. Interesting relationships between the trajectories and SLA fields are found. According to the angle between the SLA gradient and the trajectories of birds, we classify drifts into three scenarios: perpendicular, parallel and other, which are associated with different driving forces. The first scenario implies that bird drift is driven by geostrophic sea surface currents. The second we associate with wind drag as the main driving force. This is validated through the wind dataset. Moreover, from the SST, FSLEs and the eddy tracker, we obtain supplementary information on the presence of oceanic structures (such as eddies or fronts), not observed in the SLA field due to its limited spatial and temporal resolutions. Therefore, this data helps to explain some of the third case scenario trajectories.

Numerical simulations and observations of surface wave fields under an extreme tropical cyclone

USGS Publications Warehouse

Fan, Y.; Ginis, I.; Hara, T.; Wright, C.W.; Walsh, E.J.

2009-01-01

The performance of the wave model WAVEWATCH III under a very strong, category 5, tropical cyclone wind forcing is investigated with different drag coefficient parameterizations and ocean current inputs. The model results are compared with field observations of the surface wave spectra from an airborne scanning radar altimeter, National Data Buoy Center (NDBC) time series, and satellite altimeter measurements in Hurricane Ivan (2004). The results suggest that the model with the original drag coefficient parameterization tends to overestimate the significant wave height and the dominant wavelength and produces a wave spectrum with narrower directional spreading. When an improved drag parameterization is introduced and the wave-current interaction is included, the model yields an improved forecast of significant wave height, but underestimates the dominant wavelength. When the hurricane moves over a preexisting mesoscale ocean feature, such as the Loop Current in the Gulf of Mexico or a warm-and cold-core ring, the current associated with the feature can accelerate or decelerate the wave propagation and significantly modulate the wave spectrum. ?? 2009 American Meteorological Society.

A Northward Shift of the North Atlantic Ocean Intertropical Convergence Zone in Response to Summertime Saharan Dust Outbreaks

NASA Technical Reports Server (NTRS)

Wilcox, Eric M.; Lau, K. M.; Kim, Kyu-Myong

2010-01-01

The influence on the summertime North Atlantic Ocean inter-tropical convergence zone (ITCZ) of Saharan dust outbreaks is explored using nine years of continuous satellite observations and atmospheric reanalysis products. During dust outbreak events rainfall along the ITCZ shifts northward by 1 to 4 degrees latitude. Dust outbreaks coincide with warmer lower-tropospheric temperatures compared to low dust conditions, which is attributable to advection of the warm Saharan Air Layer, enhanced subtropical subsidence, and radiative heating of dust. The enhanced positive meridional temperature gradient coincident with dust outbreaks is accompanied by an acceleration of the easterly winds on the n011h side of the African Easterly Jet (AEJ). The center of the positive vorticity region south of the AEJ moves north drawing the center of low-level convergence and ITCZ rainfall northward with it. The enhanced precipitation on the north side of the ITCZ occurs in spite of widespread sea surface temperature cooling north of the ITCZ owing to reduced surface solar insolation by dust scattering.

Natural chlorine and fluorine in the atmosphere, water and precipitation

NASA Technical Reports Server (NTRS)

Friend, James P.

1990-01-01

The geochemical cycles of chlorine and fluorine are surveyed and summarized as framework for the understanding of the global natural abundances of these species in the atmosphere, water, and precipitation. In the cycles the fluxes into and out of the atmosphere can be balanced within the limits of our knowledge of the natural sources and sinks. Sea salt from the ocean surfaces represent the predominant portion of the source of chlorine. It is also an important source of atmospheric fluorine, but volcanoes are likely to be more important fluorine sources. Dry deposition of sea salt returns about 85 percent of the salt released there. Precipitation removes the remainder. Most of the sea salt materials are considered to be cyclic, moving through sea spray over the oceans and either directly back to the oceans or deposited dry and in precipitation on land, whence it runs off into rivers and streams and returns to the oceans. Most of the natural chlorine in the atmosphere is in the form of particulate chloride ion with lesser amounts as gaseous inorganic chloride and methyl chloride vapor. Fluorine is emitted from volcanoes primarily as HF. It is possible that HF may be released directly form the ocean surface but this has not been confirmed by observation. HCl and most likely HF gases are released into the atmosphere by sea salt aerosols. The mechanism for the release is likely to be the provision of protons from the so-called excess sulfate and HNO3. Sea salt aerosol contains fluorine as F(-), MgF(+), CaF(+), and NaF. The concentrations of the various species of chlorine and fluorine that characterize primarily natural, unpolluted atmospheres are summarized in tables and are discussed in relation to their fluxes through the geochemical cycle.

Scatterometer Observes Extratropical Transition of Pacific Typhoons

NASA Technical Reports Server (NTRS)

Liu, W. Timothy; Tang, Wenqing; Dunbar, R. Scott

1997-01-01

From September 15 to 25, 1996, NASA's scatterometer (NSCAT) monitored the evolution of twin typhoons, Violet and Tom, as they moved north from the western tropical Pacific, acquiring features of mid-latitude storms. The typhoons developed frontal structures, increased asymmetry, and dry air was introduced into their cores. Violet hit Japan, causing death and destruction (Figure 1), and Tom merged with a mid-latitude trough and evolved into a large extratropical storm with gale-force winds (Figure 2). We understand relatively little about the extratropical transition of tropical cyclones because of the complex thermodynamics involved [e.g., Sinclair, 1993], but we do know that the mid-latitude storms resulting from tropical cyclones usually generate strong winds and heavy precipitation. Since the transition usually occurs over the ocean, few measurements have been made. The transition is a fascinating science problem, but it also has important economic consequences. The transition occurs over the busiest trans-ocean shipping lanes, and when the resulting storms hit land, they usually devastate populated areas. NSCAT was successfully launched into a near-polar, sun-synchronous orbit on the Japanese Advanced Earth Observing Satellite (ADEOS) in August 1996 from Tanegashima Space Center in Japan. NSCAT's six antennas send microwave pulses at a frequency of 14 GHz to the Earth's surface and measure the backscatter. The antennas scan two 600-km bands of the ocean, which are separated by a 330-km data gap. From NSCAT observations, surface wind vectors can be derived at 25-km spatial resolution, covering 77% of the ice-free ocean in one day and 97% of the ocean in two days, under both clear and cloudy conditions.

TOPEX/El Nino Watch - El Nino Warm Water Pool Decreasing, Jan, 08, 1998

NASA Technical Reports Server (NTRS)

1998-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on Jan. 8, 1998, and sea surface height is an indicator of the heat content of the ocean. The volume of the warm water pool related to the El Nino has decreased by about 40 percent since its maximum in early November, but the area of the warm water pool is still about one and a half times the size of the continental United States. The volume measurements are computed as the sum of all the sea surface height changes as compared to normal ocean conditions. In addition, the maximum water temperature in the eastern tropical Pacific, as measured by the National Oceanic and Atmospheric Administration (NOAA), is still higher than normal. Until these high temperatures diminish, the El Nino warm water pool still has great potential to disrupt global weather because the high water temperatures directly influence the atmosphere. Oceanographers believe the recent decrease in the size of the warm water pool is a normal part of El Nino's natural rhythm. TOPEX/Poseidon has been tracking these fluctuations of the El Nino warm pool since it began in early 1997. These sea surface height measurements have provided scientists with their first detailed view of how El Nino's warm pool behaves because the TOPEX/Poseidon satellite measures the changing sea surface height with unprecedented precision. In this image, the white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration, (NOAA), has issued an advisory indicating the presence of a strong El Nino condition throughout the winter.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov

Sculpted by water, elevated by earthquakes—The coastal landscape of Glacier Bay National Park, Alaska

USGS Publications Warehouse

Witter, Robert C.; LeWinter, Adam; Bender, Adrian M.; Glennie, Craig; Finnegan, David

2017-05-22

Within Glacier Bay National Park in southeastern Alaska, the Fairweather Fault represents the onshore boundary between two of Earth’s constantly moving tectonic plates: the North American Plate and the Yakutat microplate. Satellite measurements indicate that during the past few decades the Yakutat microplate has moved northwest at a rate of nearly 5 centimeters per year relative to the North American Plate. Motion between the tectonic plates results in earthquakes on the Fairweather Fault during time intervals spanning one or more centuries. For example, in 1958, a 260-kilometer section of the Fairweather Fault ruptured during a magnitude 7.8 earthquake, causing permanent horizontal (as much as 6.5 meters) and vertical (as much as 1 meter) displacement of the ground surface across the fault. Thousands to millions of years of tectonic plate motion, including earthquakes like the one in 1958, raised and shifted the ground surface across the Fairweather Fault, while rivers, glaciers, and ocean waves eroded and sculpted the surrounding landscape along the Gulf of Alaska coast in Glacier Bay National Park.

Sharing Data in the Global Ocean Observing System (Invited)

NASA Astrophysics Data System (ADS)

Lindstrom, E. J.; McCurdy, A.; Young, J.; Fischer, A. S.

2010-12-01

We examine the evolution of data sharing in the field of physical oceanography to highlight the challenges now before us. Synoptic global observation of the ocean from space and in situ platforms has significantly matured over the last two decades. In the early 1990’s the community data sharing challenges facing the World Ocean Circulation Experiment (WOCE) largely focused on the behavior of individual scientists. Satellite data sharing depended on the policy of individual agencies. Global data sets were delivered with considerable delay and with enormous personal sacrifice. In the 2000’s the requirements for global data sets and sustained observations from the likes of the U.N. Framework Convention on Climate Change have led to data sharing and cooperation at a grander level. It is more effective and certainly more efficient. The Joint WMO/IOC Technical Commission on Oceanography and Marine Meteorology (JCOMM) provided the means to organize many aspects of data collection and data dissemination globally, for the common good. In response the Committee on Earth Observing Satellites organized Virtual Constellations to enable the assembly and sharing of like kinds of satellite data (e.g., sea surface topography, ocean vector winds, and ocean color). Individuals in physical oceanography have largely adapted to the new rigors of sharing data for the common good, and as a result of this revolution new science has been enabled. Primary obstacles to sharing have shifted from the individual level to the national level. As we enter into the 2010’s the demands for ocean data continue to evolve with an expanded requirement for more real-time reporting and broader disciplinary coverage, to answer key scientific and societal questions. We are also seeing the development of more numerous national contributions to the global observing system. The drivers for the establishment of global ocean observing systems are expanding beyond climate to include biological and biogeochemical issues (e.g. biodiversity and ecosystem services, fisheries collapse, and ocean acidification). This expanded suite of demands and drivers challenge us further to share data for the common good across specialties. This requires that more ocean scientific communities and national ocean observing programs move towards maturity in terms of global data collection capability, sharing capacity, and data management standards. In oceanography the time has arrived for a cultural shift toward more shared collective observing capabilities. Necessarily we must also rapidly move toward harmony in national data sharing policies for the ocean environment. Building capacity to share ocean observations has been an objective for decades and has resulted in an expanded understanding of technologies and management policies that foster data sharing and provenance tracking.

Dynamics of the turbidity maximum zone in a macrotidal estuary (the Gironde, France): Observations from field and MODIS satellite data

NASA Astrophysics Data System (ADS)

Doxaran, David; Froidefond, Jean-Marie; Castaing, Patrice; Babin, Marcel

2009-02-01

Over a 1-year period, field and satellite measurements of surface water turbidity were combined in order to study the dynamics of the turbidity maximum zone (TM) in a macrotidal estuary (the Gironde, France). Four fixed platforms equipped with turbidity sensors calibrated to give the suspended particulate matter (SPM) concentration provided continuous information in the upper estuary. Full resolution data recorded by the moderate resolution imaging spectroradiometer (MODIS) sensors onboard the Terra and Aqua satellite platforms provided information in the central and lower estuary twice a day (depending on cloud cover). Field data were used to validate a recently developed SPM quantification algorithm applied to the MODIS 'surface reflectance' product. The algorithm is based on a relationship between the SPM concentration and a reflectance ratio of MODIS bands 2 (near-infrared) and 1 (red). Based on 62 and 75 match-ups identified in 2005 with MODIS Terra and Aqua data, the relative uncertainty of the algorithm applied to these sensors was found to be 22 and 18%, respectively. Field measurements showed the tidal variations of turbidity in the upper estuary, while monthly-averaged MODIS satellite data complemented by field data allowed observing the monthly movements of the TM in the whole estuary. The trapping of fine sediments occurred in the upper estuary during the period of low river flow. This resulted in the formation of a highly concentrated TM during a 4-month period. With increasing river flow, the TM moved rapidly to the central estuary. A part of the TM detached, moved progressively in the lower estuary and was finally either massively exported to the ocean during peak floods or temporary trapped (settled) on intertidal mudflats. The massive export to the ocean was apparently the result of combined favorable environmental conditions: presence of fluid mud near the mouth, high river flow, high tides and limited wind speeds. The mean SPM concentration within surface waters of the whole estuary showed strong seasonal variations but remained almost unchanged on a 1-year-basis. These observations suggest that the masses of suspended sediments exported toward the ocean and supplied by the rivers were almost equivalent during the year investigated (2005). Results show the usefulness of information extracted from combined field and current ocean color satellite data in order to monitor the transport of suspended particles in coastal and estuarine waters.

Influence of Transient Atmospheric Circulation on the Surface Heating of the Pacific Warm Pool

NASA Technical Reports Server (NTRS)

Chou, Ming-Dah; Chou, Shu-Hsien; Chan, Pui-King

2003-01-01

Analyses of data on clouds, winds, and surface heat fluxes show that the transient behavior of basin-wide large-scale circulation has a significant influence on the warm pool sea surface temperature (SST). Trade winds converge to regions of the highest SST in the equatorial western Pacific. These regions have the largest cloud cover and smallest wind speed. Both surface solar heating and evaporative cooling are weak. The reduced evaporative cooling due to weakened winds exceeds the reduced solar heating due to enhanced cloudiness. The result is a maximum surface heating in the strong convective and high SST regions. Data also show that the maximum surface heating in strong convective regions is interrupted by transient atmospheric and oceanic circulation. Due to the seasonal variation of the insolation at the top of the atmosphere, trade winds and clouds also experience seasonal variations. Regions of high SST and low-level convergence follow the Sun, where the surface heating is a maximum. As the Sun moves away from a convective region, the strong trade winds set in, and the evaporative cooling enhances, resulting in a net cooling of the surface. During an El Nino, the maximum SST and convective region shifts eastward from the maritime continent to the equatorial central Pacific. Following the eastward shift of the maximum SST, the region of maximum cloudiness and surface heating also shift eastward. As the atmospheric and oceanic circulation returns to normal situations, the trade winds increase and the surface heating decreases. We conclude that the evaporative cooling associated with the seasonal and interannual variations of trade winds is one of the major factors that modulate the SST distribution of the Pacific warm pool.

Observational-numerical Study of Maritime Extratropical Cyclones Using FGGE Data

NASA Technical Reports Server (NTRS)

Wash, C. H.; Elsberry, R. L.

1984-01-01

The accomplishments, current research, and future plans of a study investigating the development, maturation, and decay of maritime extratropical cyclones are reported. Three cases of explosive cyclogenesis during the first GARP global experiment (FGGE) DOP-1 were studied diagnostically using storm-following budgets derived from the ECMWF and GLAS level III-b analyses. Mass, vorticity and angular momentum budgets for the moving storm environment were computed for each case. Key results from these studies include: (1) demonstration that the FGGE analyses can be used to explore oceanic circulations; (2) isolation of the role of upper level jet streaks in the initiation of the explosive period in all three cases; and (3) illustration of the lower tropospheric destabilization during each rapid deepening period, which is primarily due to sensible heating of the cold air by the warmer ocean surface. The physics package of the Navy global forecast model was successfully utilized in a semi-prognostic mode to estimate diabatic components of oceanic cyclone systems. Fields of sensible and latent heat fluxes, radiational heating and inferred cloud structures were also computed.

Development of An Autonomous Underwater Glider for Observing Physical Ocean Parameters in Indonesian Seas

NASA Astrophysics Data System (ADS)

Ajie Linarka, Utoyo; Riyanto Trilaksono, Bambang; Sagala, M. Faisal; Hidayat, Egi; Sopaheluwakan, Ardhasena; Rizal, Jose; Heriyanto, Eko; Amsal Harapan, Ferdika; Eka Syahputra Makmur, Erwin

2017-04-01

Conducting a sustained monitoring and surveying of physical ocean parameters for research or operational purposes using moorings and ships would require high cost. Development of an inexpensive instrument capable to perform such tasks not only could reduce cost and risks but also increase cruising range and depth. For that reason, a prototype of underwater glider was developed, named "GaneshBlue". GaneshBlue works based on gliding principles which utilizes pitch angle and buoyancy control for moving. For one gliding movement, GaneshBlue passed through 5 phases of surface, descent, transition, ascent and back to surface. The glider is equipped with basic navigation system and remote control, programmable survey planning, temperature and salinity sampling instruments, lithium batteries for power supply, and information processing software. A field test at the shallow water showed that GaneshBule has successfully demonstrated gliding and surfacing movements with surge motion speed reaching 20 cm s-1and 20 m in depths. During the field test the glider was also equipped with three instruments, i.e. Inertial Measurement Unit (IMU) to estimate glider's speed and orientation; MiniCT to acquire temperature and conductivity data; and Altisounder to determine its distance to sea surface and to seabed. In general, all the instruments performed well but filter algorithm needs to be implemented on data collection procedure to remove data outliers.

Thoughts on why in CESM a more poleward TOA energy imbalance favors more ocean-centric energy transport and weaker ITCZ shift responses

NASA Astrophysics Data System (ADS)

Yu, S.; Pritchard, M. S.

2017-12-01

The role of different location of top-of-atmosphere (TOA) solar forcing to the annual-mean, zonal-mean ITCZ location is examined in a dynamic ocean coupled Community Earth System Model. We observe a damped ITCZ shift response that is now a familiar response of coupled GCMs, but a new finding is that the damping efficiency is increases monotonically as the latitudinal location of forcing is moved poleward. More Poleward forcing cases exhibit weaker shifts of the annual-mean ITCZ position consistent with a more ocean-centric cross-equatorial energy partitioning response to the forcing, which is in turn linked to changes in ocean circulation, not thermodynamic structure. The ocean's dynamic response is partly due to Ekman-driven shallow overturning circulation responses, as expected from a recent theory, but also contains a significant Atlantic meridional overturning circulation (AMOC) component--which is in some sense surprising given that it is activated even in near-tropical forcing experiments. Further analysis of the interhemispheric energy budget reveals the surface heating feedback response provides a useful framework for interpreting the cross-equatorial energy transport partitioning between atmosphere and ocean. Overall, the results of this study may help explain the mixed results of the degree of ITCZ shift response to interhemispheric asymmetric forcing documented in coupled GCMs in recent years. Furthermore, the sensitive AMOC response motivates expanding current coupled theoretical frameworks on meridional energy transport partitioning to include effects beyond Ekman transport.

KSC-2014-2513

NASA Image and Video Library

2014-05-12

CAPE CANAVERAL, Fla. – Part of NASA's International Space Station-RapidScat scatterometer instrument is moved into Space Station Processing Facility at Kennedy Space Center in Florida. ISS-RapidScat is the first scientific Earth-observing instrument designed to operate from the exterior of the space station. It will measure Earth's ocean surface wind speed and direction, providing data to be used in weather and marine forecasting. Built at NASA's Jet Propulsion Laboratory, ISS-RapidScat is slated to fly on the SpaceX-4 commercial cargo resupply flight in 2014. For more information, visit http://www.jpl.nasa.gov/missions/iss-rapidscat. Photo credit: NASA/Dimitri Gerondidakis

Airships for transporting highly volatile commodities

NASA Technical Reports Server (NTRS)

Sonstegaard, M.

1975-01-01

Large airships may prove feasible as carriers of commodities that move as gases or cryogenic liquids; buoyant gaseous cargo could be ballasted with liquid cargo. Airships are compact in shape, operate in a rarified medium, and hence can be fast and perhaps economic carriers of costly cryogenic tanks. The high-pressure gas pipeline has excessive surface area when carrying hydrogen and excessive fluid density when carrying natural gas, while the cryogenic ocean tanker runs in a dense medium and makes gravity waves. But the airship, despite its fluid dynamic advantages, faces problems of safety, weather, and altitude control.

Advances in Small Remotely Piloted Aircraft Communications and Remote Sensing in Maritime Environments including the Arctic

NASA Astrophysics Data System (ADS)

McGillivary, P. A.; Borges de Sousa, J.; Wackowski, S.; Walker, G.

2011-12-01

Small remotely piloted aircraft have recently been used for maritime remote sensing, including launch and retrieval operations from land, ships and sea ice. Such aircraft can also function to collect and communicate data from other ocean observing system platforms including moorings, tagged animals, drifters, autonomous surface vessels (ASVs), and autonomous underwater vessels (AUVs). The use of small remotely piloted aircraft (or UASs, unmanned aerial systems) with a combination of these capabilities will be required to monitor the vast areas of the open ocean, as well as in harsh high-latitude ecosystems. Indeed, these aircraft are a key component of planned high latitude maritime domain awareness environmental data collection capabilities, including use of visible, IR and hyperspectral sensors, as well as lidar, meteorological sensors, and interferometric synthetic aperture radars (ISARs). We here first describe at-sea demonstrations of improved reliability and bandwidth of communications from ocean sensors on autonomous underwater vehicles to autonomous surface vessels, and then via remotely piloted aircraft to shore, ships and manned aircraft using Delay and Disruption Tolerant (DTN) communication protocols. DTN enables data exchange in communications-challenged environments, such as remote regions of the ocean including high latitudes where low satellite angles and auroral disturbances can be problematic. DTN provides a network architecture and application interface structured around optionally-reliable asynchronous message forwarding, with limited expectations of end-to-end connectivity and node resources. This communications method enables aircraft and surface vessels to function as data mules to move data between physically disparate nodes. We provide examples of the uses of this communication protocol for environmental data collection and data distribution with a variety of different remotely piloted aircraft in a coastal ocean environment. Next, we highlight use in the arctic of two different small remotely piloted aircraft (ScanEagle and RAVEN) for remote sensing of ice and ocean conditions as well as surveys of marine mammals. Finally, we explain how these can be used in future networked environments with DTN support not only for the collection of ocean and ice data for maritime domain awareness, but also for monitoring oil spill dynamics in high latitude environments, including spills in and under sea ice. The networked operation of heterogeneous air and ocean vehicle systems using DTN communications methods can provide unprecedented levels of spatial-temporal sampling resolution important to improving arctic remote sensing and maritime domain awareness capabilities.

Control of climate and Tethyan legacy on distribution of Paleocene–Eocene gastropods and establishment of the Northern Tropical Realm

NASA Astrophysics Data System (ADS)

Das, Shrestha; Halder, Kalyan

2018-06-01

Palaeobiogeographical distribution of gastropod genera from the Paleocene and the Eocene has been analysed. Based on this distribution, formal palaeobiogeographical provinces have been established and their relationships are sought. It has been found that the provinces were largely restricted to the palaeo-tropics and subtropics mainly of the northern hemisphere and they share a large proportion of their generic composition. The Northern Tropical Realm has been established to include these provinces. The distribution evinces presence of ocean surface currents in the tropics across longitudes. The possible currents moved through the relict Tethys Ocean, across the Atlantic Ocean and perhaps also across the Pacific. However, planktotrophic larvae of these benthic molluscs could not cross the deep ocean barrier that lay between the Northern Tropical Realm and the Austro-New Zealand Province of the southern hemisphere. The gastropod fauna in the latter province evolved independently. Distribution of all the provinces within palaeo-tropics and subtropics indicates strong control of temperature over it. Paleocene-Eocene Thermal Maximum appears to be responsible for extinction and range contraction of high latitude faunas. Low latitude faunas also suffered significant extinction. However, large diversification in the Eocene was a response to widespread transgression that coincided with the thermal event.

Microwave Limb Sounder/El Nino Watch - Water Vapor Measurement, October, 1997

NASA Technical Reports Server (NTRS)

1997-01-01

This image shows atmospheric water vapor in Earth's upper troposphere, about 10 kilometers (6 miles) above the surface, as measured by the Microwave Limb Sounder (MLS) instrument flying aboard the Upper Atmosphere Research Satellite. These data collected in early October 1997 indicate the presence of El Nino by showing a shift of humidity from west to east (blue and red areas) along the equatorial Pacific Ocean. El Nino is the term used when the warmest equatorial Pacific Ocean water is displaced toward the east. The areas of high atmospheric moisture correspond to areas of very warm ocean water. Warmer water evaporates at a higher rate and the resulting warm moist air then rises, forming tall cloud towers. In the tropics, the warm water and the resulting tall cloud towers typically produce large amounts of rain. The MLS instrument, developed at NASA's Jet Propulsion Laboratory, measures humidity at the top of these clouds, which are very moist. This rain is now occurring in the eastern Pacific Ocean and has left Indonesia (deep blue region) unusually dry, resulting in the current drought in that region. This image also shows moisture moving north into Mexico, an effect of several hurricanes spawned by the warm waters of El Nino.

GISS Analysis of Surface Temperature Changes

NASA Technical Reports Server (NTRS)

Hansen, J.; Ruedy, R.; Glascoe, J.; Sato, M.

1999-01-01

We describe the current GISS analysis of surface temperature change based primarily on meteorological station measurements. The global surface temperature in 1998 was the warmest in the period of instrumental data. The rate of temperature change is higher in the past 25 years than at any previous time in the period of instrumental data. The warmth of 1998 is too large and pervasive to be fully accounted for by the recent El Nino, suggesting that global temperature may have moved to a higher level, analogous to the increase that occurred in the late 1970s. The warming in the United States over the past 50 years is smaller than in most of the world, and over that period there is a slight cooling trend in the Eastern United States and the neighboring Atlantic ocean. The spatial and temporal patterns of the temperature change suggest that more than one mechanism is involved in this regional cooling.

Blue ocean strategy.

PubMed

Kim, W Chan; Mauborgne, Renée

2004-10-01

Despite a long-term decline in the circus industry, Cirque du Soleil profitably increased revenue 22-fold over the last ten years by reinventing the circus. Rather than competing within the confines of the existing industry or trying to steal customers from rivals, Cirque developed uncontested market space that made the competition irrelevant. Cirque created what the authors call a blue ocean, a previously unknown market space. In blue oceans, demand is created rather than fought over. There is ample opportunity for growth that is both profitable and rapid. In red oceans--that is, in all the industries already existing--companies compete by grabbing for a greater share of limited demand. As the market space gets more crowded, prospects for profits and growth decline. Products turn into commodities, and increasing competition turns the water bloody. There are two ways to create blue oceans. One is to launch completely new industries, as eBay did with online auctions. But it's much more common for a blue ocean to be created from within a red ocean when a company expands the boundaries of an existing industry. In studying more than 150 blue ocean creations in over 30 industries, the authors observed that the traditional units of strategic analysis--company and industry--are of limited use in explaining how and why blue oceans are created. The most appropriate unit of analysis is the strategic move, the set of managerial actions and decisions involved in making a major market-creating business offering. Creating blue oceans builds brands. So powerful is blue ocean strategy, in fact, that a blue ocean strategic move can create brand equity that lasts for decades.

Processes of 30-90 days sea surface temperature variability in the northern Indian Ocean during boreal summer

NASA Astrophysics Data System (ADS)

Vialard, J.; Jayakumar, A.; Gnanaseelan, C.; Lengaigne, M.; Sengupta, D.; Goswami, B. N.

2012-05-01

During summer, the northern Indian Ocean exhibits significant atmospheric intraseasonal variability associated with active and break phases of the monsoon in the 30-90 days band. In this paper, we investigate mechanisms of the Sea Surface Temperature (SST) signature of this atmospheric variability, using a combination of observational datasets and Ocean General Circulation Model sensitivity experiments. In addition to the previously-reported intraseasonal SST signature in the Bay of Bengal, observations show clear SST signals in the Arabian Sea related to the active/break cycle of the monsoon. As the atmospheric intraseasonal oscillation moves northward, SST variations appear first at the southern tip of India (day 0), then in the Somali upwelling region (day 10), northern Bay of Bengal (day 19) and finally in the Oman upwelling region (day 23). The Bay of Bengal and Oman signals are most clearly associated with the monsoon active/break index, whereas the relationship with signals near Somali upwelling and the southern tip of India is weaker. In agreement with previous studies, we find that heat flux variations drive most of the intraseasonal SST variability in the Bay of Bengal, both in our model (regression coefficient, 0.9, against ~0.25 for wind stress) and in observations (0.8 regression coefficient); ~60% of the heat flux variation is due do shortwave radiation and ~40% due to latent heat flux. On the other hand, both observations and model results indicate a prominent role of dynamical oceanic processes in the Arabian Sea. Wind-stress variations force about 70-100% of SST intraseasonal variations in the Arabian Sea, through modulation of oceanic processes (entrainment, mixing, Ekman pumping, lateral advection). Our ~100 km resolution model suggests that internal oceanic variability (i.e. eddies) contributes substantially to intraseasonal variability at small-scale in the Somali upwelling region, but does not contribute to large-scale intraseasonal SST variability due to its small spatial scale and random phase relation to the active-break monsoon cycle. The effect of oceanic eddies; however, remains to be explored at a higher spatial resolution.

Does the Arctic Amplification peak this decade?

NASA Astrophysics Data System (ADS)

Martin, Torge; Haine, Thomas W. N.

2017-04-01

Temperatures rise faster in the Arctic than on global average, a phenomenon known as Arctic Amplification. While this is well established from observations and model simulations, projections of future climate (here: RCP8.5) with models of the Coupled Model Intercomparison Project phase 5 (CMIP5) also indicate that the Arctic Amplification has a maximum. We show this by means of an Arctic Amplification factor (AAF), which we define as the ratio of Arctic mean to global mean surface air temperature (SAT) anomalies. The SAT anomalies are referenced to the period 1960-1980 and smoothed by a 30-year running mean. For October, the multi-model ensemble-mean AAF reaches a maximum in 2017. The maximum moves however to later years as Arctic winter progresses: for the autumn mean SAT (September to November) the maximum AAF is found in 2028 and for winter (December to February) in 2060. Arctic Amplification is driven, amongst others, by the ice-albedo feedback (IAF) as part of the more general surface albedo feedback (involving clouds, snow cover, vegetation changes) and temperature effects (Planck and lapse-rate feedbacks). We note that sea ice retreat and the associated warming of the summer Arctic Ocean are not only an integral part of the IAF but are also involved in the other drivers. In the CMIP5 simulations, the timing of the AAF maximum coincides with the period of fastest ice retreat for the respective month. Presence of at least some sea ice is crucial for the IAF to be effective because of the contrast in surface albedo between ice and open water and the need to turn ocean warming into ice melt. Once large areas of the Arctic Ocean are ice-free, the IAF should be less effective. We thus hypothesize that the ice retreat significantly affects AAF variability and forces a decline of its magnitude after at least half of the Arctic Ocean is ice-free and the ice cover becomes basically seasonal.

Reducing Surface Clutter in Cloud Profiling Radar Data

NASA Technical Reports Server (NTRS)

Tanelli, Simone; Pak, Kyung; Durden, Stephen; Im, Eastwood

2008-01-01

An algorithm has been devised to reduce ground clutter in the data products of the CloudSat Cloud Profiling Radar (CPR), which is a nadir-looking radar instrument, in orbit around the Earth, that measures power backscattered by clouds as a function of distance from the instrument. Ground clutter contaminates the CPR data in the lowest 1 km of the atmospheric profile, heretofore making it impossible to use CPR data to satisfy the scientific interest in studying clouds and light rainfall at low altitude. The algorithm is based partly on the fact that the CloudSat orbit is such that the geodetic altitude of the CPR varies continuously over a range of approximately 25 km. As the geodetic altitude changes, the radar timing parameters are changed at intervals defined by flight software in order to keep the troposphere inside a data-collection time window. However, within each interval, the surface of the Earth continuously "scans through" (that is, it moves across) a few range bins of the data time window. For each radar profile, only few samples [one for every range-bin increment ((Delta)r = 240 m)] of the surface-clutter signature are available around the range bin in which the peak of surface return is observed, but samples in consecutive radar profiles are offset slightly (by amounts much less than (Delta)r) with respect to each other according to the relative change in geodetic altitude. As a consequence, in a case in which the surface area under examination is homogenous (e.g., an ocean surface), a sequence of consecutive radar profiles of the surface in that area contains samples of the surface response with range resolution (Delta)p much finer than the range-bin increment ((Delta)p << r). Once the high-resolution surface response has thus become available, the profile of surface clutter can be accurately estimated by use of a conventional maximum-correlation scheme: A translated and scaled version of the high-resolution surface response is fitted to the observed low-resolution profile. The translation and scaling factors that optimize the fit in a maximum-correlation sense represent (1) the true position of the surface relative to the sampled surface peak and (2) the magnitude of the surface backscatter. The performance of this algorithm has been tested on CloudSat data acquired over an ocean surface. A preliminary analysis of the test data showed a surface-clutter-rejection ratio over flat surfaces of >10 dB and a reduction of the contaminated altitude over ocean from about 1 km to about 0.5 km (over the ocean). The algorithm has been embedded in CloudSat L1B processing as of Release 04 (July 2007), and the estimated flat surface clutter is removed in L2B-GEOPROF product from the observed profile of reflectivity (see CloudSat product documentation for details and performance at http://www.cloudsat.cira.colostate.edu/ dataSpecs.php?prodid=1).

The Impacts of Daily Surface Forcing in the Upper Ocean over Tropical Pacific: A Numerical Study

NASA Technical Reports Server (NTRS)

Sui, C.-H.; Rienecker, Michele M.; Li, Xiaofan; Lau, William K.-M.; Laszlo, Istvan; Pinker, Rachel T.

2001-01-01

Tropical Pacific Ocean is an important region that affects global climate. How the ocean responds to the atmospheric surface forcing (surface radiative, heat and momentum fluxes) is a major topic in oceanographic research community. The ocean becomes warm when more heat flux puts into the ocean. The monthly mean forcing has been used in the past years since daily forcing was unavailable due to the lack of observations. The daily forcing is now available from the satellite measurements. This study investigates the response of the upper ocean over tropical Pacific to the daily atmospheric surface forcing. The ocean surface heat budgets are calculated to determine the important processes for the oceanic response. The differences of oceanic responses between the eastern and western Pacific are intensively discussed.

Spatial and temporal Teleconnections of Sea Surface Temperature and Ocean Indices to regional Climate Variations across Thailand - a Pathway to understanding the Impact of Climate Change on Water Resources

NASA Astrophysics Data System (ADS)

Bejranonda, Werapol; Koch, Manfred

2010-05-01

Thailand has a long coastline with the Pacific Ocean, as part of the Gulf of Thailand, as well as with the Indian Ocean, as part of the Andaman Sea. Because of this peculiar location, Thailand's local climate and, in particular, its water resources are strongly influenced by the mix of tropical wet, tropical dry and tropical monsoon seasons. Because of the large seasonal and interannual variations and irregularities of these, mainly ocean-driven weather patterns, particularly in recent times, large-scale water storage in huge river-fed reservoirs has a long tradition in Thailand, providing water for urban, industrial and agricultural use during long dry seasonal periods. These reservoirs which are located all over Thailand gather water primarily from monsoon-driven rainfall during the wet season which, usually, lasts from May to October. During the dry season, November to April, when the monsoon winds move northward, the air masses are drier in central and northern Thailand, with rain falling here only a few days in a month. Southern Thailand, on the other hand, which is constituted mostly by the isthmus between the two oceans, stays even hot and humid during that time period. Because of this tropical climate pattern, the surface water resources in most of Thailand strongly hinge on the monsoon movements which, in turn, depend themselves upon the thermal states of the Pacific and Indian Oceans. Therefore, the understanding of the recent strong seasonal and interannual climate variations with their detrimental effects on the availability of hydrological water resources in most parts of Thailand, must include the analysis of changes of various sea-state indices in the adjacent oceans and of their possible teleconnections with regional climate indices across this country. With the modern coupled atmospheric-ocean models being able to predict the variations of many ocean indices over a period of several months, namely, those driven by El Nino- Southern Oscillations (ENSO) events in the Pacific Ocean, if such teleconnections exist, one would have would have a powerful tool at hand to forecast extreme seasonal climate pattern across Thailand over a limited time period. Eventually, such a predictive tool would help to better manage the availability and adequate supply of surface water resources to the various water users in this country. In the present study the spatial and temporal relationships between the global climate circulation system and the regional weather in Thailand are assessed by various techniques of stochastic time series analysis. More specifically, the time series of the sea surface temperature (SST) and various ocean indices of the Pacific and the Indian Oceans, as well as the time series of 121 meteorological stations from 5 regions across Thailand which include humidity, evaporation, temperature and rainfall during 1950-2007 are examined using autocorrelation, ARIMA, Wavelet Transform methods. Possible teleconnections between the behaviour of the ocean states and the climate variations at meteorological stations in eastern Thailand which frequently suffers from water shortage problems are analyzed using regression, cross-correlation and the Wavelet cross-correlation method. In addition to the time series of the observed ocean and meteorological variables, 1961-2000 CGCM3 predictors of the macro-scale regional climate variations for this study area are analyzed by the methods above and correlated with the ocean indices as well. Rainfall and temperatures at selected stations are forecasted up to year 2007 using the teleconnection- relationships found by multiple linear regression with the CGCM3 predictors. In addition, autoregressive integrated moving average (ARIMA) models of these climate variable are set up that are eventually extended to include the ocean indices as external regressors. The results of these various statistical techniques show that the El-Niño 1.2 SST anomaly indice of the Pacific Ocean, which refers to the most eastern section of the Pacific, correlates the strongest with the Thai local climate. Through cross-correlation, the most sensitive parameters to the ocean indices are the minimum temperature at stations in the northern and northeastern, inland regions of Thailand and the number of rainy days in the eastern, central and southern, coastal regions. In the southern region the amount of rainfall at the coast of Gulf of Thailand varies positively with El-Niño, but negatively for stations along the Andaman Sea coast in the west of the isthmus, with maximal correlation lag.-times of 4 months. Surprisingly the corresponding connections of the local climate variables with the Indian Ocean indices are less well established, with an optimal lag-time of only 3 months. Using the results of the teleconnection regression relationships, the forecast of the local climate variables could be improved significantly, as indicated by the Nash-Sutcliffe-coefficient of the prediction model's which increased from originally 0.30, 0.72 and 0.26 to 0.51, 0.82 and 0.46 for the rainfall, minimum and maximum temperatures, respectively. The results of our analysis indicate the possibility of a better forecast of extreme seasonal climate variations across some regions of Thailand over a limited time period by using short-term expected variations of the Pacific and Indian ocean indices.

Drilling reorganizes

NASA Astrophysics Data System (ADS)

Richman, Barbara T.

As the first in a proposed series of steps that would move scientific ocean drilling from its own niche within the National Science Foundation's (NSF) Directorate for Astronomical, Atmospheric, Earth, and Ocean Sciences (AAEO) into the agency's Division of Ocean Sciences, Grant Gross, division director, has been appointed acting director of the Office of Scientific Ocean Drilling (OSOD). Gross will retain the directorship of the division, which also is part of AAEO. Allen M. Shinn, Jr., OSOD director for nearly 2 years, has been reassigned effective July 10 to a position in NSF's Office of Planning and Resource Management.The move aims to tie drilling operations more closely to the science with which it is associated, Gross said. This first step is an organizational response to the current leaning toward using a commercial drilling vessel as the drilling platform, he said. Before the market for such commercial drill ships opened (Eos, February 22, 1983, p . 73), other ship options for scientific ocean drilling included refurbishing the aging Glomar Challenger or renovating, at great expense, the Glomar Explorer. A possible next step in the reorganization is to make OSOD the third section within the Ocean Sciences Division. Currently, the division is divided into the Oceanographic Facilities and Support Section and the Ocean Sciences Research Section.

Law sets up oceans commission

NASA Astrophysics Data System (ADS)

Showstack, Randy

In an anticipated move, U.S. President Bill Clinton on August 7 signed into law the Oceans Act of 2000.The bipartisan legislation, which takes effect on January 20,2001, establishes a commission on ocean policy to examine federal ocean policy and environmental and economic trends affecting oceans and coasts.The act—which grew out of a call issued by Clinton at the National Oceans Conference in Monterey, California in 1998—requires the commission to submit recommendations to Congress and the president within 18 months of its appointment, and for the President to submit proposals to Congress about the use and stewardship of ocean and coastal resources.

Estimates of effective elastic thickness of oceanic lithosphere using model including surface and subsurface loads and effective elastic thickness of subduction zones

NASA Astrophysics Data System (ADS)

Yang, A.; Yongtao, F.

2016-12-01

The effective elastic thickness (Te) is an important parameter that characterizes the long term strength of the lithosphere, which has great significance on understanding the mechanical properties and evolution of the lithosphere. In contrast with many controversies regarding elastic thickness of continent lithosphere, the Te of oceanic lithosphere is thought to be in a simple way that is dependent on the age of the plate. However, rescent studies show that there is no simple relationship between Te and age at time of loading for both seamounts and subduction zones. As subsurface loading is very importand and has large influence in the estimate of Te for continent lithosphere, and many oceanic features such as subduction zones also have considerable subsurface loading. We introduce the method to estimate the effective elastic thickness of oceanic lithosphere using model including surface and subsurface loads by using free-air gravity anomaly and bathymetric data, together with a moving window admittance technique (MWAT). We use the multitaper spectral estimation method to calculate the power spectral density. Through tests with synthetic subduction zone like bathymetry and gravity data show that the Te can be recovered in an accurance similar to that in the continent and there is also a trade-off between spatial resolution and variance for different window sizes. We estimate Te of many subduction zones (Peru-Chile trench, Middle America trench, Caribbean trench, Kuril-Japan trench, Mariana trench, Tonga trench, Java trench, Ryukyu-Philippine trench) with an age range of 0-160 Myr to reassess the relationship between elastic thickness and the age of the lithosphere at the time of loading. The results do not show a simple relationship between Te and age.

Cloud Motion in the GOCI COMS Ocean Colour Data

NASA Technical Reports Server (NTRS)

Robinson, Wayne D.; Franz, Bryan A.; Mannino, Antonio; Ahn, Jae-Hyun

2016-01-01

The Geostationary Ocean Colour Imager (GOCI) instrument, on Koreas Communications, Oceans, and Meteorological Satellite (COMS), can produce a spectral artefact arising from the motion of clouds the cloud is spatially shifted and the amount of shift varies by spectral band. The length of time it takes to acquire all eight GOCI bands for a given slot (portion of a scene) is sucient to require that cloud motion be taken into account to fully mask or correct the eects of clouds in all bands. Inter-band correlations can be used to measure the amount of cloud shift, which can then be used to adjust the cloud mask so that the union of all shifted masks can act as a mask for all bands. This approach reduces the amount of masking required versus a simple expansion of the mask in all directions away from clouds. Cloud motion can also aect regions with unidentied clouds thin or fractional clouds that evade the cloud identication process yielding degraded quality in retrieved ocean colour parameters. Areas with moving and unidentied clouds require more elaborate masking algo-rithms to remove these degraded retrievals. Correction for the eects of moving fractional clouds may also be possible. The cloud shift information can be used to determine cloud motion and thus wind at the cloud levels on sub-minute timescales. The benecial and negative eects of moving clouds should be con-sidered for any ocean colour instrument design and associated data processing plans.

Ocean circulation and climate during the past 120,000 years

NASA Astrophysics Data System (ADS)

Rahmstorf, Stefan

2002-09-01

Oceans cover more than two-thirds of our blue planet. The waters move in a global circulation system, driven by subtle density differences and transporting huge amounts of heat. Ocean circulation is thus an active and highly nonlinear player in the global climate game. Increasingly clear evidence implicates ocean circulation in abrupt and dramatic climate shifts, such as sudden temperature changes in Greenland on the order of 5-10 °C and massive surges of icebergs into the North Atlantic Ocean - events that have occurred repeatedly during the last glacial cycle.

The Heritage of the Operational Usda/nasa Global Reservoir and Lake Monitor

NASA Astrophysics Data System (ADS)

Birkett, C. M.; Beckley, B. D.; Reynolds, C. A.

2012-12-01

Satellite radar altimetry has the ability to monitor variations in surface water height for large lakes and reservoirs. A clear advantage is the provision of data where in situ data are lacking or where there is restricted access to ground-based measurements. A USDA/NASA funded program is performing altimetric monitoring of the largest lakes and reservoirs around the world. The near-real time height measurements are currently derived from NASA/CNES Jason-2/OSTM mission data. Archived data are also utilized from the NASA/CNES Topex/Poseidon and Jason-1 missions, the NRL GFO mission, and the ESA ENVISAT mission. Lake level products are output within 1-2 weeks after satellite overpass, a time delay which will improve to a few days as the project moves into its next phase. The USDA/FAS utilize the products for assessing irrigation potential (and thus crop production estimates), and for general observation of high-water status and short-term drought. Other end-users explore the products to study climate trends, observe anthropogenic effects, and to consider water management and regional security issues. This presentation explores the heritage of the Global Reservoir and Lake Monitor (GRLM) which has its origins in the field of ocean surface topography and the exploration of radar altimetry techniques over non-ocean surfaces. The current system closely follows the software design of the historical NASA Ocean Pathfinder Project and utilizes a global lakes catalogue that was created for climate change/aridity studies. The output of lake level products, imagery and information also echoes an earlier trial (UNDP-funded) lakes database which first offered altimetric products via the world wide web and which enabled world-wide interest to be both assessed and highlighted.;

A dynamical systems approach to the surface search for debris associated with the disappearance of flight MH370

NASA Astrophysics Data System (ADS)

García-Garrido, V. J.; Mancho, A. M.; Wiggins, S.; Mendoza, C.

2015-11-01

The disappearance of Malaysia Airlines flight MH370 on the morning of 8 March 2014 is one of the great mysteries of our time. Perhaps the most relevant aspect of this mystery is that not a single piece of debris from the aircraft was found during the intensive surface search carried out for roughly 2 months following the crash. Difficulties in the search efforts, due to the uncertainty of the plane's final impact point and the time that had passed since the accident, bring the question on how the debris scattered in an always moving ocean, for which there are multiple data sets that do not uniquely determine its state. Our approach to this problem is based on the use of Lagrangian descriptors (LD), a novel mathematical tool coming from dynamical systems theory that identifies dynamic barriers and coherent structures governing transport. By combining publicly available information supplied by different ocean data sources with these mathematical techniques, we are able to assess the spatio-temporal state of the ocean in the priority search area at the time of impact and the following weeks. Using this information we propose a revised search strategy by showing why one might not have expected to find debris in some large search areas targeted by the Australian Maritime Safety Authority (AMSA), and determining regions where one might have expected impact debris to be located, which were not subjected to any exploration.

The ocean-atmosphere response to wind-induced thermocline changes in the tropical South Western Indian Ocean

NASA Astrophysics Data System (ADS)

Manola, Iris; Selten, F. M.; de Ruijter, W. P. M.; Hazeleger, W.

2015-08-01

In the Indian Ocean basin the sea surface temperatures (SSTs) are most sensitive to changes in the oceanic depth of the thermocline in the region of the Seychelles Dome. Observational studies have suggested that the strong SST variations in this region influence the atmospheric evolution around the basin, while its impact could extend far into the Pacific and the extra-tropics. Here we study the adjustments of the coupled atmosphere-ocean system to a winter shallow doming event using dedicated ensemble simulations with the state-of-the-art EC-Earth climate model. The doming creates an equatorial Kelvin wave and a pair of westward moving Rossby waves, leading to higher SST 1-2 months later in the Western equatorial Indian Ocean. Atmospheric convection is strengthened and the Walker circulation responds with reduced convection over Indonesia and cooling of the SST in that region. The Pacific warm pool convection shifts eastward and an oceanic Kelvin wave is triggered at thermocline depth. The wave leads to an SST warming in the East Equatorial Pacific 5-6 months after the initiation of the Seychelles Dome event. The atmosphere responds to this warming with weak anomalous atmospheric convection. The changes in the upper tropospheric divergence in this sequence of events create large-scale Rossby waves that propagate away from the tropics along the atmospheric waveguides. We suggest to repeat these types of experiments with other models to test the robustness of the results. We also suggest to create the doming event in June so that the East-Pacific warming occurs in November when the atmosphere is most sensitive to SST anomalies and El Niño could possibly be triggered by the doming event under suitable conditions.

The PRISM3D paleoenvironmental reconstruction

USGS Publications Warehouse

Dowsett, H.; Robinson, M.; Haywood, A.M.; Salzmann, U.; Hill, Daniel; Sohl, L.E.; Chandler, M.; Williams, Mark; Foley, K.; Stoll, D.K.

2010-01-01

The Pliocene Research, Interpretation and Synoptic Mapping (PRISM) paleoenvironmental reconstruction is an internally consistent and comprehensive global synthesis of a past interval of relatively warm and stable climate. It is regularly used in model studies that aim to better understand Pliocene climate, to improve model performance in future climate scenarios, and to distinguish model-dependent climate effects. The PRISM reconstruction is constantly evolving in order to incorporate additional geographic sites and environmental parameters, and is continuously refined by independent research findings. The new PRISM three dimensional (3D) reconstruction differs from previous PRISM reconstructions in that it includes a subsurface ocean temperature reconstruction, integrates geochemical sea surface temperature proxies to supplement the faunal-based temperature estimates, and uses numerical models for the first time to augment fossil data. Here we describe the components of PRISM3D and describe new findings specific to the new reconstruction. Highlights of the new PRISM3D reconstruction include removal of Hudson Bay and the Great Lakes and creation of open waterways in locations where the current bedrock elevation is less than 25m above modern sea level, due to the removal of the West Antarctic Ice Sheet and the reduction of the East Antarctic Ice Sheet. The mid-Piacenzian oceans were characterized by a reduced east-west temperature gradient in the equatorial Pacific, but PRISM3D data do not imply permanent El Niño conditions. The reduced equator-to-pole temperature gradient that characterized previous PRISM reconstructions is supported by significant displacement of vegetation belts toward the poles, is extended into the Arctic Ocean, and is confirmed by multiple proxies in PRISM3D. Arctic warmth coupled with increased dryness suggests the formation of warm and salty paleo North Atlantic Deep Water (NADW) and a more vigorous thermohaline circulation system that may have provided the enhanced ocean heat transport necessary to move warm surface water to the Arctic. New deep ocean temperature data also suggests greater warmth and further southward penetration of paleo NADW.

Large eddy simulation of heat entrainment under Arctic sea ice

NASA Astrophysics Data System (ADS)

Ramudu, Eshwan; Gelderloos, Renske; Yang, Di; Meneveau, Charles; Gnanadesikan, Anand

2017-11-01

Sea ice cover in the Arctic has declined rapidly in recent decades. To better understand ice loss through bottom melting, we choose to study the Canada Basin of the Arctic Ocean, which is characterized by a perennial anomalously warm Pacific Summer Water (PSW) layer residing at the base of the mixed layer and a summertime Near-Surface Temperature Maximum (NSTM) layer trapping heat from solar radiation. The interaction of these warm layers with a moving ice basal surface is investigated using large eddy simulation. We find that the presence of the NSTM enhances heat entrainment from the mixed layer. Another conclusion from our work is that there is no heat entrained from the PSW layer, even at the largest ice-drift velocity of 0.3 m s-1 considered. We propose a scaling law for the heat flux at the ice basal surface which depends on the initial temperature anomaly in the NSTM layer and the ice-drift velocity. A case study of `The Great Arctic Cyclone of 2012' gives a turbulent heat flux from the mixed layer that is approximately 70% of the total ocean-to-ice heat flux estimated from the PIOMAS model often used for short-term predictions. Present results highlight the need for large-scale climate models to account for the NSTM layer. We acknowledge funding from NOAA Grant NA15OAR4310172, the NSF, and the University of Houston start-up fund.

Behavioral responses of Atlantic cod to sea temperature changes.

PubMed

Freitas, Carla; Olsen, Esben Moland; Moland, Even; Ciannelli, Lorenzo; Knutsen, Halvor

2015-05-01

Understanding responses of marine species to temperature variability is essential to predict impacts of future climate change in the oceans. Most ectotherms are expected to adjust their behavior to avoid extreme temperatures and minimize acute changes in body temperature. However, measuring such behavioral plasticity in the wild is challenging. Combining 4 years of telemetry-derived behavioral data on juvenile and adult (30-80 cm) Atlantic cod (Gadus morhua), and in situ ocean temperature measurements, we found a significant effect of sea temperature on cod depth use and activity level in coastal Skagerrak. During summer, cod were found in deeper waters when sea surface temperature increased. Further, this effect of temperature was stronger on larger cod. Diel vertical migration, which consists in a nighttime rise to shallow feeding habitats, was stronger among smaller cod. As surface temperature increased beyond ∼15°C, their vertical migration was limited to deeper waters. In addition to larger diel vertical migrations, smaller cod were more active and travelled larger distances compared to larger specimens. Cold temperatures during winter tended, however, to reduce the magnitude of diel vertical migrations, as well as the activity level and distance moved by those smaller individuals. Our findings suggest that future and ongoing rises in sea surface temperature may increasingly deprive cod in this region from shallow feeding areas during summer, which may be detrimental for local populations of the species.

Behavioral responses of Atlantic cod to sea temperature changes

PubMed Central

Freitas, Carla; Olsen, Esben Moland; Moland, Even; Ciannelli, Lorenzo; Knutsen, Halvor

2015-01-01

Understanding responses of marine species to temperature variability is essential to predict impacts of future climate change in the oceans. Most ectotherms are expected to adjust their behavior to avoid extreme temperatures and minimize acute changes in body temperature. However, measuring such behavioral plasticity in the wild is challenging. Combining 4 years of telemetry-derived behavioral data on juvenile and adult (30–80 cm) Atlantic cod (Gadus morhua), and in situ ocean temperature measurements, we found a significant effect of sea temperature on cod depth use and activity level in coastal Skagerrak. During summer, cod were found in deeper waters when sea surface temperature increased. Further, this effect of temperature was stronger on larger cod. Diel vertical migration, which consists in a nighttime rise to shallow feeding habitats, was stronger among smaller cod. As surface temperature increased beyond ∼15°C, their vertical migration was limited to deeper waters. In addition to larger diel vertical migrations, smaller cod were more active and travelled larger distances compared to larger specimens. Cold temperatures during winter tended, however, to reduce the magnitude of diel vertical migrations, as well as the activity level and distance moved by those smaller individuals. Our findings suggest that future and ongoing rises in sea surface temperature may increasingly deprive cod in this region from shallow feeding areas during summer, which may be detrimental for local populations of the species. PMID:26045957

Current structure of strongly nonlinear interfacial solitary waves

NASA Astrophysics Data System (ADS)

Semin, Sergey; Kurkina, Oxana; Kurkin, Andrey; Talipova, Tatiana; Pelinovsky, Efim; Churaev, Egor

2015-04-01

The characteristics of highly nonlinear solitary internal waves (solitons) in two-layer flow are computed within the fully nonlinear Navier-Stokes equations with use of numerical model of the Massachusetts Institute of Technology (MITgcm). The verification and adaptation of the model is based on the data from laboratory experiments [Carr & Davies, 2006]. The present paper also compares the results of our calculations with the computations performed in the framework of the fully nonlinear Bergen Ocean Model [Thiem et al, 2011]. The comparison of the computed soliton parameters with the predictions of the weakly nonlinear theory based on the Gardner equation is given. The occurrence of reverse flow in the bottom layer directly behind the soliton is confirmed in numerical simulations. The trajectories of Lagrangian particles in the internal soliton on the surface, on the interface and near the bottom are computed. The results demonstrated completely different trajectories at different depths of the model area. Thus, in the surface layer is observed the largest displacement of Lagrangian particles, which can be more than two and a half times larger than the characteristic width of the soliton. Located at the initial moment along the middle pycnocline fluid particles move along the elongated vertical loop at a distance of not more than one third of the width of the solitary wave. In the bottom layer of the fluid moves in the opposite direction of propagation of the internal wave, but under the influence of the reverse flow, when the bulk of the velocity field of the soliton ceases to influence the trajectory, it moves in the opposite direction. The magnitude of displacement of fluid particles in the bottom layer is not more than the half-width of the solitary wave. 1. Carr, M., and Davies, P.A. The motion of an internal solitary wave of depression over a fixed bottom boundary in a shallow, two-layer fluid. Phys. Fluids, 2006, vol. 18, No. 1, 1 - 10. 2. Thiem, O., Carr, M., Berntsen, J., and Davies, P.A. Numerical simulation of internal solitary wave-induced reverse flow and associated vortices in a shallow, two-layer fluid benthic boundary layer. Ocean Dynamics, 2011, vol. 61, No. 6, 857 - 872.

Response of near-surface currents in the Indian Ocean to the anomalous atmospheric condition in 2015

NASA Astrophysics Data System (ADS)

Utari, P. A.; Nurkhakim, M. Y.; Setiabudidaya, D.; Iskandar, I.

2018-05-01

Anomalous ocean-atmosphere conditions were detected in the tropical Indian Ocean during boreal spring to boreal winter 2015. It was suggested that the anomalous conditions were characteristics of the positive Indian Ocean Dipole (pIOD) event. The purpose of this investigation was to investigate the response of near-surface currents in the tropical Indian Ocean to the anomalous atmospheric condition in 2015. Near-surface current from OSCAR (Ocean Surface Current Analyses Real Time) reanalysis data combined with the sea surface temperature (SST) data from OISST – NOAA, sea surface height (SSH) and surface winds from the ECMWF were used in this investigation. The analysis showed that the evolution of 2015 pIOD started in June/July, peaked in the September and terminated in late November 2015. Correlated with the evolution of the pIOD, easterly winds anomalies were detected along the equator. As the oceanic response to these easterly wind anomalies, the surface currents anomalously westward during the peak of the pIOD. It was interesting to note that the evolution of 2015 pIOD event was closely related to the ocean wave dynamics as revealed by the SSH data. Downwelling westward propagating Rossby waves were detected in the southwestern tropical Indian Ocean. Once reached the western boundary of the Indian Ocean, they were redirected back into interior Indian Ocean and propagating eastward as the downwelling Kelvin waves.

KSC-2014-2506

NASA Image and Video Library

2014-05-12

CAPE CANAVERAL, Fla. – A component of NASA's International Space Station-RapidScat scatterometer instrument is moved via forklift into the Space Station Processing Facility at Kennedy Space Center in Florida. ISS-RapidScat is the first scientific Earth-observing instrument designed to operate from the exterior of the space station. It will measure Earth's ocean surface wind speed and direction, providing data to be used in weather and marine forecasting. Built at NASA's Jet Propulsion Laboratory, ISS-RapidScat is slated to fly on the SpaceX-4 commercial cargo resupply flight in 2014. For more information, visit http://www.jpl.nasa.gov/missions/iss-rapidscat. Photo credit: NASA/Dimitri Gerondidakis

KSC-2014-2514

NASA Image and Video Library

2014-05-12

CAPE CANAVERAL, Fla. – The components of NASA's International Space Station-RapidScat scatterometer instrument are moved into a laboratory inside Kennedy Space Center's Space Station Processing Facility. ISS-RapidScat is the first scientific Earth-observing instrument designed to operate from the exterior of the space station. It will measure Earth's ocean surface wind speed and direction, providing data to be used in weather and marine forecasting. Built at NASA's Jet Propulsion Laboratory, ISS-RapidScat is slated to fly on the SpaceX-4 commercial cargo resupply flight in 2014. For more information, visit http://www.jpl.nasa.gov/missions/iss-rapidscat. Photo credit: NASA/Dimitri Gerondidakis

KSC-2014-2507

NASA Image and Video Library

2014-05-12

CAPE CANAVERAL, Fla. – A component of NASA's International Space Station-RapidScat scatterometer instrument is moved via forklift into the Space Station Processing Facility at Kennedy Space Center in Florida. ISS-RapidScat is the first scientific Earth-observing instrument designed to operate from the exterior of the space station. It will measure Earth's ocean surface wind speed and direction, providing data to be used in weather and marine forecasting. Built at NASA's Jet Propulsion Laboratory, ISS-RapidScat is slated to fly on the SpaceX-4 commercial cargo resupply flight in 2014. For more information, visit http://www.jpl.nasa.gov/missions/iss-rapidscat. Photo credit: NASA/Dimitri Gerondidakis

Does Southern Ocean Surface Forcing Shape the Global Ocean Overturning Circulation?

NASA Astrophysics Data System (ADS)

Sun, Shantong; Eisenman, Ian; Stewart, Andrew L.

2018-03-01

Paleoclimate proxy data suggest that the Atlantic Meridional Overturning Circulation (AMOC) was shallower at the Last Glacial Maximum (LGM) than its preindustrial (PI) depth. Previous studies have suggested that this shoaling necessarily accompanies Antarctic sea ice expansion at the LGM. Here the influence of Southern Ocean surface forcing on the AMOC depth is investigated using ocean-only simulations from a state-of-the-art climate model with surface forcing specified from the output of previous coupled PI and LGM simulations. In contrast to previous expectations, we find that applying LGM surface forcing in the Southern Ocean and PI surface forcing elsewhere causes the AMOC to shoal only about half as much as when LGM surface forcing is applied globally. We show that this occurs because diapycnal mixing renders the Southern Ocean overturning circulation more diabatic than previously assumed, which diminishes the influence of Southern Ocean surface buoyancy forcing on the depth of the AMOC.

High Resolution Photogrammetric Digital Elevation Models Across Calving Fronts and Meltwater Channels in Greenland

NASA Astrophysics Data System (ADS)

Le Bel, D. A.; Brown, S.; Zappa, C. J.; Bell, R. E.; Frearson, N.; Tinto, K. J.

2014-12-01

Photogrammetric digital elevation models (DEMs) are a powerful approach for understanding elevation change and dynamics along the margins of the large ice sheets. The IcePod system, mounted on a New York Air National Guard LC-130, can measure high-resolution surface elevations with a Riegl VQ580 scanning laser altimeter and Imperx Bobcat IGV-B6620 color visible-wavelength camera (6600x4400 resolution); the surface temperature with a Sofradir IRE-640L infrared camera (spectral response 7.7-9.5 μm, 640x512 resolution); and the structure of snow and ice with two radar systems. We show the use of IcePod imagery to develop DEMs across calving fronts and meltwater channels in Greenland. Multiple over-flights of the Kangerlussaq Airport ramp have provided a test of the technique at a location with accurate, independently-determined elevation. Here the photogrammetric DEM of the airport, constrained by ground control measurements, is compared with the Lidar results. In July 2014 the IcePod ice-ocean imaging system surveyed the calving fronts of five outlet glaciers north of Jakobshavn Isbrae. We used Agisoft PhotoScan to develop a DEM of each calving front using imagery captured by the IcePod systems. Adjacent to the ice sheet, meltwater plumes foster mixing in the fjord, moving warm ocean water into contact with the front of the ice sheet where it can undercut the ice front and trigger calving. The five glaciers provide an opportunity to examine the calving front structure in relation to ocean temperature, fjord circulation, and spatial scale of the meltwater plumes. The combination of the accurate DEM of the calving front and the thermal imagery used to constrain the temperature and dynamics of the adjacent plume provides new insights into the ice-ocean interactions. Ice sheet margins provide insights into the connections between the surface meltwater and the fate of the water at the ice sheet base. Surface meltwater channels are visualized here for the first time using the combination of Lidar, photogrammetry DEMs and infrared imagery. These techniques leverage electromagnetic surface properties that allow us to identify the presence of water, measure the slope and elevation of the channel, as well as the two-dimensional temperature variability of the water/ice/snow in multiple melt channels within a drainage system.

MODIS Global Sea Surface Temperature

NASA Technical Reports Server (NTRS)

2002-01-01

Every day the Moderate-resolution Imaging Spectroradiometer (MODIS) measures sea surface temperature over the entire globe with high accuracy. This false-color image shows a one-month composite for May 2001. Red and yellow indicates warmer temperatures, green is an intermediate value, while blues and then purples are progressively colder values. The new MODIS sea surface temperature product will be particularly useful in studies of temperature anomalies, such as El Nino, as well as research into how air-sea interactions drive changes in weather and climate patterns. In the high resolution image, notice the amazing detail in some of the regional current patterns. For instance, notice the cold water currents that move from Antarctica northward along South America's west coast. These cold, deep waters upwell along an equatorial swath around and to the west of the Galapagos Islands. Note the warm, wide currents of the Gulf Stream moving up the United States' east coast, carrying Caribbean warmth toward Newfoundland and across the Atlantic toward Western Europe. Note the warm tongue of water extending from Africa's east coast to well south of the Cape of Good Hope. MODIS was launched in December 1999 aboard NASA's Terra satellite. For more details on this and other MODIS data products, please see NASA Unveils Spectacular Suite of New Global Data Products from MODIS. Image courtesy MODIS Ocean Group, NASA GSFC, and the University of Miami

Strait of Gibraltar as seen from STS-60

NASA Image and Video Library

1994-02-09

STS060-88-070 (3-11 Feb 1994) --- This view shows sunglint in the Strait of Gibralter. In this photograph a high pressure atmospheric system over the Iberian Peninsula has set the conditions for seeing a plankton bloom along the Moroccan coast in the Alboran Sea (Western Mediterranean) coastal counter current as well as illumining the influence of winds in the sunglint pattern near the Strait of Gibraltar. Where the water is ruffled from a wind gust, such as off Cadiz, Spain, the surface is less reflective and thus appears dark. A combination of the effects of the tide and the surface winds through the Strait of Gibraltar have created a unique sunglint pattern at the entrance of the Mediterranean. The Atlantic Ocean waters are flowing with the tide through the Strait of Gibraltar into the Mediterranean Sea and are probably smoothing out some of the smaller waves at the surface. The incoming tide generates internal waves as can be faintly seen in this photograph. The incoming relatively cooler, less dense Atlantic water flows over the warm, more saline Mediterranean water. As the tide moves into the Strait of Gibraltar it encounters the Camarinal Sill, which is like a cliff under the water, south of Camarinal Point, Spain. Internal waves are generated at this sill and they travel along the density boundary between the Atlantic water and the Mediterranean water masses. There is little evidence of the internal waves at the surface of the ocean. We can see them in spacecraft photography because of the sunglint which reflects off the different water layers in differential patterns. The internal waves also smooth out some of the bands of capillary waves at the surface. That is, the sun reflects more brightly from these smooth areas, showing the pattern of the underwater waves more prominently than do the surface waves. The Bay of Cadiz on the southwest coast of Spain, the Rock of Gibraltar, and the Moroccan coast are also beautifully illustrated in this photography. The focus for scientists, however, remains the high clarity and spatial resolution given by sunglint studies to physical phenomena in the ocean.

Climate change and Southern Ocean ecosystems I: how changes in physical habitats directly affect marine biota.

PubMed

Constable, Andrew J; Melbourne-Thomas, Jessica; Corney, Stuart P; Arrigo, Kevin R; Barbraud, Christophe; Barnes, David K A; Bindoff, Nathaniel L; Boyd, Philip W; Brandt, Angelika; Costa, Daniel P; Davidson, Andrew T; Ducklow, Hugh W; Emmerson, Louise; Fukuchi, Mitsuo; Gutt, Julian; Hindell, Mark A; Hofmann, Eileen E; Hosie, Graham W; Iida, Takahiro; Jacob, Sarah; Johnston, Nadine M; Kawaguchi, So; Kokubun, Nobuo; Koubbi, Philippe; Lea, Mary-Anne; Makhado, Azwianewi; Massom, Rob A; Meiners, Klaus; Meredith, Michael P; Murphy, Eugene J; Nicol, Stephen; Reid, Keith; Richerson, Kate; Riddle, Martin J; Rintoul, Stephen R; Smith, Walker O; Southwell, Colin; Stark, Jonathon S; Sumner, Michael; Swadling, Kerrie M; Takahashi, Kunio T; Trathan, Phil N; Welsford, Dirk C; Weimerskirch, Henri; Westwood, Karen J; Wienecke, Barbara C; Wolf-Gladrow, Dieter; Wright, Simon W; Xavier, Jose C; Ziegler, Philippe

2014-10-01

Antarctic and Southern Ocean (ASO) marine ecosystems have been changing for at least the last 30 years, including in response to increasing ocean temperatures and changes in the extent and seasonality of sea ice; the magnitude and direction of these changes differ between regions around Antarctica that could see populations of the same species changing differently in different regions. This article reviews current and expected changes in ASO physical habitats in response to climate change. It then reviews how these changes may impact the autecology of marine biota of this polar region: microbes, zooplankton, salps, Antarctic krill, fish, cephalopods, marine mammals, seabirds, and benthos. The general prognosis for ASO marine habitats is for an overall warming and freshening, strengthening of westerly winds, with a potential pole-ward movement of those winds and the frontal systems, and an increase in ocean eddy activity. Many habitat parameters will have regionally specific changes, particularly relating to sea ice characteristics and seasonal dynamics. Lower trophic levels are expected to move south as the ocean conditions in which they are currently found move pole-ward. For Antarctic krill and finfish, the latitudinal breadth of their range will depend on their tolerance of warming oceans and changes to productivity. Ocean acidification is a concern not only for calcifying organisms but also for crustaceans such as Antarctic krill; it is also likely to be the most important change in benthic habitats over the coming century. For marine mammals and birds, the expected changes primarily relate to their flexibility in moving to alternative locations for food and the energetic cost of longer or more complex foraging trips for those that are bound to breeding colonies. Few species are sufficiently well studied to make comprehensive species-specific vulnerability assessments possible. Priorities for future work are discussed. © 2014 John Wiley & Sons Ltd.

Observational study of upper ocean cooling due to Phet super cyclone in the Arabian Sea

NASA Astrophysics Data System (ADS)

Muni Krishna, K.

2016-05-01

Phet super cyclone (31 May-7 June 2010) was the most intense and also the rarest of the rare track in Arabian Sea as per the recorded history during 1877-2009. The present study focuses on the ocean physical responses to Phet cyclone using satellite and Argo observations. The sea surface temperature is decreased to 6 °C with an approximately 350 km long and 100 km width area in the Arabian Sea after the cyclone passage. The translation speed of cyclone is 3.86 m/s, the mixed layer is 79 m, and thermocline displacement is 13 m at the cooling area. With the relationship of wind stress curl and Ekman pumping velocity (EPV), the author found that the speed of EPV was increased after the passage of cyclone. So the extent of the SST drop was probably due to the moving speed of cyclone and the depth of the mixed layer.

Analysis and prediction of ocean swell using instrumented buoys

NASA Technical Reports Server (NTRS)

Mettlach, Theodore; Wang, David; Wittmann, Paul

1994-01-01

During the period 20-23 September 1990, the remnants of Supertyphoon Flo moved into the central North Pacific Ocean with sustained wind speeds of 28 m/s. The strong wind and large fetch area associated with this storm generated long-period swell that propagated to the west coast of North America. National Data Buoy Center moored-buoy stations, located in a network that ranged from the Gulf of Alaska to the California Bight, provided wave spectral estimates of the swell from this storm. The greatest dominant wave periods measured were approximately 20-25 s, and significant wave heights measured ranged from 3 to 8 m. Wave spectra from an array of three nondirectional buoys are used to find the source of the long-period swell. Directional wave spectra from a heave-pitch-roll buoy are also used to make an independent estimate of the source of the swell. The ridge-line method, using time-frequency contour plots of wave spectral energy density, is used to determine the time of swell generation, which is used with the appropriate surface pressure analysis to infer the swell generation area. The diagnosed sources of the swell are also compared with nowcasts from the Global Spectral Ocean Wave Model of the Fleet Numerical Oceanography Center. A simple method of predicting the propagation of ocean swell, by applying a simple kinematic model of wave propagation to the estimated point and time source, is demonstrated.

Ocean floor mounting of wave energy converters

DOEpatents

Siegel, Stefan G

2015-01-20

A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

Vertical Redistribution of Ocean Salt Content

NASA Astrophysics Data System (ADS)

Liang, X.; Liu, C.; Ponte, R. M.; Piecuch, C. G.

2017-12-01

Ocean salinity is an important proxy for change and variability in the global water cycle. Multi-decadal trends have been observed in both surface and subsurface salinity in the past decades, and are usually attributed to the change in air-sea freshwater flux. Although air-sea freshwater flux, a major component of the global water cycle, certainly contributes to the change in surface and upper ocean salinity, the salt redistribution inside the ocean can affect the surface and upper ocean salinity as well. Also, the mechanisms controlling the surface and upper ocean salinity changes likely depend on timescales. Here we examined the ocean salinity changes as well as the contribution of the vertical redistribution of salt with a 20-year dynamically consistent and data-constrained ocean state estimate (ECCO: Estimating Circulation and Climate of the Ocean). A decrease in the spatial mean upper ocean salinity and an upward salt flux inside the ocean were observed. These findings indicate that over 1992-2011, surface freshwater fluxes contribute to the decrease in spatial mean upper ocean salinity and are partly compensated by the vertical redistribution of salt inside the ocean. Between advection and diffusion, the two major processes determining the vertical exchange of salt, the advective term at different depths shows a downward transport, while the diffusive term is the dominant upward transport contributor. These results suggest that the salt transport in the ocean interior should be considered in interpreting the observed surface and upper ocean salinity changes, as well as inferring information about the changes in the global water cycle.

Pegasus XL CYGNSS Move to AIT

NASA Image and Video Library

2016-11-17

At Vandenberg Air Force Base in California, an Orbital ATK Pegasus XL rocket is placed on an assembly integration transporter for the move from the hangar at Building 1555 to be mated to L-1011 carrier aircraft near Vandenberg's runway. On board Pegasus are eight NASA Cyclone Global Navigation Satellite System, or CYGNSS, spacecraft. When preparations are competed at Vandenberg, the L-1011/Pegasus XL combination will be flown to NASA’s Kennedy Space Center in Florida. On Dec. 12, 2016, the carrier aircraft is scheduled to take off from the Skid Strip at Cape Canaveral Air Force Station and CYGNSS will launch on the Pegasus XL rocket with the L-1011 flying off shore. CYGNSS satellites will make frequent and accurate measurements of ocean surface winds throughout the life cycle of tropical storms and hurricanes. The data that CYGNSS provides will enable scientists to probe key air-sea interaction processes that take place near the core of storms, which are rapidly changing and play a critical role in the beginning and intensification of hurricanes.

Lindstrom Receives 2013 Ocean Sciences Award: Response

NASA Astrophysics Data System (ADS)

Lindstrom, Eric J.

2014-09-01

My sincere thanks go to the AGU Ocean Sciences section for this award. Is there any higher honor than recognition by one's peers? To join the illustrious list of prior recipients is deeply moving. Thanks so much to Arnold and Gary for their abundant praise and support over many years.

Ocean Wave Simulation Based on Wind Field

PubMed Central

2016-01-01

Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates. PMID:26808718

Slow and Steady: Ocean Circulation. The Influence of Sea Surface Height on Ocean Currents

NASA Technical Reports Server (NTRS)

Haekkinen, Sirpa

2000-01-01

The study of ocean circulation is vital to understanding how our climate works. The movement of the ocean is closely linked to the progression of atmospheric motion. Winds close to sea level add momentum to ocean surface currents. At the same time, heat that is stored and transported by the ocean warms the atmosphere above and alters air pressure distribution. Therefore, any attempt to model climate variation accurately must include reliable calculations of ocean circulation. Unlike movement of the atmosphere, movement of the ocean's waters takes place mostly near the surface. The major patterns of surface circulation form gigantic circular cells known as gyres. They are categorized according to their general location-equatorial, subtropical, subpolar, and polar-and may run across an entire ocean. The smaller-scale cell of ocean circulation is known' as an eddy. Eddies are much more common than gyres and much more difficult to track in computer simulations of ocean currents.

Ocean Wave Simulation Based on Wind Field.

PubMed

Li, Zhongyi; Wang, Hao

2016-01-01

Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates.

A WebGIS system on the base of satellite data processing system for marine application

NASA Astrophysics Data System (ADS)

Gong, Fang; Wang, Difeng; Huang, Haiqing; Chen, Jianyu

2007-10-01

From 2002 to 2004, a satellite data processing system for marine application had been built up in State Key Laboratory of Satellite Ocean Environment Dynamics (Second Institute of Oceanography, State Oceanic Administration). The system received satellite data from TERRA, AQUA, NOAA-12/15/16/17/18, FY-1D and automatically generated Level3 products and Level4 products(products of single orbit and merged multi-orbits products) deriving from Level0 data, which is controlled by an operational control sub-system. Currently, the products created by this system play an important role in the marine environment monitoring, disaster monitoring and researches. Now a distribution platform has been developed on this foundation, namely WebGIS system for querying and browsing of oceanic remote sensing data. This system is based upon large database system-Oracle. We made use of the space database engine of ArcSDE and other middleware to perform database operation in addition. J2EE frame was adopted as development model, and Oracle 9.2 DBMS as database background and server. Simply using standard browsers(such as IE6.0), users can visit and browse the public service information that provided by system, including browsing for oceanic remote sensing data, and enlarge, contract, move, renew, traveling, further data inquiry, attribution search and data download etc. The system is still under test now. Founding of such a system will become an important distribution platform of Chinese satellite oceanic environment products of special topic and category (including Sea surface temperature, Concentration of chlorophyll, and so on), for the exaltation of satellite products' utilization and promoting the data share and the research of the oceanic remote sensing platform.

Wind Turbine Clutter Mitigation in Coastal UHF Radar

PubMed Central

Wang, Caijun; Jiang, Dapeng; Wen, Biyang

2014-01-01

Coastal UHF radar provides a unique capability to measure the sea surface dynamic parameters and detect small moving targets, by exploiting the low energy loss of electromagnetic waves propagating along the salty and good conducting ocean surface. It could compensate the blind zone of HF surface wave radar at close range and reach further distance than microwave radars. However, its performance is susceptible to wind turbines which are usually installed on the shore. The size of a wind turbine is much larger than the wavelength of radio waves at UHF band, which results in large radar cross section. Furthermore, the rotation of blades adds time-varying Doppler frequency to the clutter and makes the suppression difficult. This paper proposes a mitigation method which is based on the specific periodicity of wind turbine clutter and performed mainly in the time-frequency domain. Field experimental data of a newly developed UHF radar are used to verify this method, and the results prove its effectiveness. PMID:24550709

Wind turbine clutter mitigation in coastal UHF radar.

PubMed

Yang, Jing; Pan, Chao; Wang, Caijun; Jiang, Dapeng; Wen, Biyang

2014-01-01

Coastal UHF radar provides a unique capability to measure the sea surface dynamic parameters and detect small moving targets, by exploiting the low energy loss of electromagnetic waves propagating along the salty and good conducting ocean surface. It could compensate the blind zone of HF surface wave radar at close range and reach further distance than microwave radars. However, its performance is susceptible to wind turbines which are usually installed on the shore. The size of a wind turbine is much larger than the wavelength of radio waves at UHF band, which results in large radar cross section. Furthermore, the rotation of blades adds time-varying Doppler frequency to the clutter and makes the suppression difficult. This paper proposes a mitigation method which is based on the specific periodicity of wind turbine clutter and performed mainly in the time-frequency domain. Field experimental data of a newly developed UHF radar are used to verify this method, and the results prove its effectiveness.

Pole-to-pole biogeography of surface and deep marine bacterial communities

PubMed Central

Ghiglione, Jean-François; Galand, Pierre E.; Pommier, Thomas; Pedrós-Alió, Carlos; Maas, Elizabeth W.; Bakker, Kevin; Bertilson, Stefan; Kirchman, David L.; Lovejoy, Connie; Yager, Patricia L.; Murray, Alison E.

2012-01-01

The Antarctic and Arctic regions offer a unique opportunity to test factors shaping biogeography of marine microbial communities because these regions are geographically far apart, yet share similar selection pressures. Here, we report a comprehensive comparison of bacterioplankton diversity between polar oceans, using standardized methods for pyrosequencing the V6 region of the small subunit ribosomal (SSU) rRNA gene. Bacterial communities from lower latitude oceans were included, providing a global perspective. A clear difference between Southern and Arctic Ocean surface communities was evident, with 78% of operational taxonomic units (OTUs) unique to the Southern Ocean and 70% unique to the Arctic Ocean. Although polar ocean bacterial communities were more similar to each other than to lower latitude pelagic communities, analyses of depths, seasons, and coastal vs. open waters, the Southern and Arctic Ocean bacterioplankton communities consistently clustered separately from each other. Coastal surface Southern and Arctic Ocean communities were more dissimilar from their respective open ocean communities. In contrast, deep ocean communities differed less between poles and lower latitude deep waters and displayed different diversity patterns compared with the surface. In addition, estimated diversity (Chao1) for surface and deep communities did not correlate significantly with latitude or temperature. Our results suggest differences in environmental conditions at the poles and different selection mechanisms controlling surface and deep ocean community structure and diversity. Surface bacterioplankton may be subjected to more short-term, variable conditions, whereas deep communities appear to be structured by longer water-mass residence time and connectivity through ocean circulation. PMID:23045668

Global monitoring of Sea Surface Salinity with Aquarius

NASA Technical Reports Server (NTRS)

Lagerloef, G. S. E.; LeVine, D. M.; Chao, Yi; Colomb, R.; Nollmann, I.

2005-01-01

Aquarius is a microwave remote sensing system designed to obtain global maps of the surface salinity field of the oceans from space. It will be flown on the Aquarius/SAC-D mission, a partnership between the USA (NASA) and Argentina (CONAE) with launch scheduled for late in 2008. The objective of Aquarius is to monitor the seasonal and interannual variation of the large scale features of the surface salinity field in the open ocean. This will provide data to address scientific questions associated with ocean circulation and its impact on climate. For example, salinity is needed to understand the large scale thermohaline circulation, driven by buoyancy, which moves large masses of water and heat around the globe. Of the two variables that determine buoyancy (salinity and temperature), temperature is already being monitored. Salinity is the missing variable needed to understand this circulation. Salinity also has an important role in energy exchange between the ocean and atmosphere, for example in the development of fresh water lenses (buoyant water that forms stable layers and insulates water below from the atmosphere) which alter the air-sea coupling. Aquarius is a combination radiometer and scatterometer (radar) operating at L-band (1.413 GHz for the radiometer and 1.26 GHz for the scatterometer). The primary instrument,for measuring salinity is the radiometer which is able to detect salinity because of the modulation salinity produces on the thermal emission from sea water. This change is detectable at the long wavelength end of the microwave spectrum. The scatterometer will provide a correction for surface roughness (waves) which is one of the greatest unknowns in the retrieval. The sensor will be in a sun-synchronous orbit at about 650 km with equatorial crossings of 6am/6pm. The antenna for these two instruments is a 3 meter offset fed reflector with three feeds arranged in pushbroom fashion looking away from the sun toward the shadow side of the orbit to minimize sunglint. The mission goal is to produce maps of the salinity field globally once each month with an accuracy of 0.2 psu and a spatial resolution of 100 km. This will be adequate to address l&ge scale features of the salinity field of the open ocean. The temporal resolution is sufficient to address seasonal changes and a three year mission is planned to-collect sufficient data to look for interannual variation. Aquarius is being developed by NASA as part of the Earth System Science Pathfinder (ESSP) program. The SAC-D mission is being developed by CONAE and will include the space craft and several additional instruments, including visible and infrared cameras and a microwave radiometer to monitor rain and wind velocity over the oceans, and sea ice.

Variational Data Assimilation for the Global Ocean

DTIC Science & Technology

2013-01-01

ocean includes the Geoid (a fixed gravity equipotential surface ) as well as the MDT, which is not known accurately enough relative to the centimeter...scales, including processes that control the surface mixed layer, the formation of ocean eddies, meandering ocean J.A. Cummings (E3) nography Division...variables. Examples of this in the ocean are integral quantities, such as acous^B travel time and altimeter measures of sea surface height, and direct

How well-connected is the surface of the global ocean?

PubMed

Froyland, Gary; Stuart, Robyn M; van Sebille, Erik

2014-09-01

The Ekman dynamics of the ocean surface circulation is known to contain attracting regions such as the great oceanic gyres and the associated garbage patches. Less well-known are the extents of the basins of attractions of these regions and how strongly attracting they are. Understanding the shape and extent of the basins of attraction sheds light on the question of the strength of connectivity of different regions of the ocean, which helps in understanding the flow of buoyant material like plastic litter. Using short flow time trajectory data from a global ocean model, we create a Markov chain model of the surface ocean dynamics. The surface ocean is not a conservative dynamical system as water in the ocean follows three-dimensional pathways, with upwelling and downwelling in certain regions. Using our Markov chain model, we easily compute net surface upwelling and downwelling, and verify that it matches observed patterns of upwelling and downwelling in the real ocean. We analyze the Markov chain to determine multiple attracting regions. Finally, using an eigenvector approach, we (i) identify the five major ocean garbage patches, (ii) partition the ocean into basins of attraction for each of the garbage patches, and (iii) partition the ocean into regions that demonstrate transient dynamics modulo the attracting garbage patches.

Warm and Saline Events Embedded in the Meridional Circulation of the Northern North Atlantic

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa; Rhines, Peter B.; Worthen, Denise L.

2011-01-01

Ocean state estimates from 1958 to 2005 from the Simple Ocean Assimilation System (SODA) system are analyzed to understand circulation between subtropical and subpolar Atlantic and their connection with atmospheric forcing. This analysis shows three periods (1960s, around 1980, and 2000s) with enhanced warm, saline waters reaching high latitudes, alternating with freshwater events originating at high latitudes. It complements surface drifter and altimetry data showing the subtropical -subpolar exchange leading to a significant temperature and salinity increase in the northeast Atlantic after 2001. The warm water limb of the Atlantic meridional overturning cell represented by SODA expanded in density/salinity space during these warm events. Tracer simulations using SODA velocities also show decadal variation of the Gulf Stream waters reaching the subpolar gyre and Nordic seas. The negative phase of the North Atlantic Oscillation index, usually invoked in such variability, fails to predict the warming and salinization in the early 2000s, with salinities not seen since the 1960s. Wind stress curl variability provided a linkage to this subtropical/subpolar gyre exchange as illustrated using an idealized two ]layer circulation model. The ocean response to the modulation of the climatological wind stress curl pattern was found to be such that the northward penetration of subtropical tracers is enhanced when amplitude of the wind stress curl is weaker than normal. In this case both the subtropical and subpolar gyres weaken and the subpolar density surfaces relax; hence, the polar front moves westward, opening an enhanced northward access of the subtropical waters in the eastern boundary current.

A Dynamical System Approach to the Surface Search of Debris from MH370

NASA Astrophysics Data System (ADS)

Mancho, Ana M.; Garcia-Garrido, V. J.; Wiggins, S.; Mendoza, C.

2015-11-01

The disappearance of Malaysia Airlines flight MH370 on the morning of the 8th of March 2014 is one of the great mysteries of our time. One relevant aspect of this mystery is that not a single piece of debris from the aircraft was found during the intensive surface search carried out in the months following the crash. Difficulties in the search efforts, due to the uncertainty in the plane's final impact point and the time passed since the accident, brought the question on how the debris was scattered in an always moving ocean, for which there were multiple datasets that do not uniquely determined its state. Our approach to this problem is based on dynamical systems tools that identify dynamic barriers and coherent structures governing transport. By combining different ocean data with these mathematical techniques, we are able to assess the spatio-temporal state of the ocean in the priority search area at the time of impact and the following weeks. Using this information we propose a revised search strategy by showing why one might not have expected to find debris in some large search areas targeted by the search services and determining regions where one might have expected impact debris to be located and that have not been subjected to any exploration. This research has been supported by MINECO under grants MTM2014-56392-R and ICMAT Severo Ochoa project SEV-2011-0087 and ONR grant No. N00014- 01-1-0769. Computational support from CESGA is acknowledged.

Titan's Surface Diversity and Ongoing Processes-A Review

NASA Astrophysics Data System (ADS)

Soderblom, Laurence A.

2012-04-01

Titan’s landscapes exhibit a wealth of surface diversity that rivals the glossary for a textbook on Earth’s geomorphological styles and geological processes. Long before Cassini-Huygens’ arrival, evidence suggested that Titan’s surface might harbor liquid hydrocarbons, methane and ethane, in the form of lakes, seas, or even oceans. And, as the surface gradually became visible to the Huygens Probe on its slow descent, it became clear that liquids had been quite active in sculpting and dissecting the terrains: a network of dendritic channels densely drapes the highlands located a few kilometers north of the landing site. This led Tomasko and colleagues to lead off the title of their Huygens report with “Rain, winds and haze …” And not only were winds responsible for the Probe’s erratic change in direction as it neared the surface but soon we discovered that they also drive vast seas of longitudinal dunes eastward, wrapping the equatorial zone. Current thinking is that the dunes consist of coarse grains of solid hydrocarbons, perhaps mixed with water ice, that saltate in the slow-moving dense atmosphere. And, although we did not find vast methane-ethane oceans, we did find polar lakes and seas, vast in the north and sparse in the south. Elsewhere impact, tectonic, and, more arguably, volcanic features appear to be ubiquitous. The subjects of Titan’s geology continue to cascade into a host of new details of the subjects of process and geomorphology; the collection terms, familiar to terrestrial science, continues to grow. References: Tomasko, M. G., et al. (2005) “Rain, winds and haze during the Huygens probe’s descent to Titan’s surface”. Nature, Vol. 438, pp.775-778.

Influence of ice thickness and surface properties on light transmission through Arctic sea ice

PubMed Central

Arndt, Stefanie; Nicolaus, Marcel; Perovich, Donald K.; Jakuba, Michael V.; Suman, Stefano; Elliott, Stephen; Whitcomb, Louis L.; McFarland, Christopher J.; Gerdes, Rüdiger; Boetius, Antje; German, Christopher R.

2015-01-01

Abstract The observed changes in physical properties of sea ice such as decreased thickness and increased melt pond cover severely impact the energy budget of Arctic sea ice. Increased light transmission leads to increased deposition of solar energy in the upper ocean and thus plays a crucial role for amount and timing of sea‐ice‐melt and under‐ice primary production. Recent developments in underwater technology provide new opportunities to study light transmission below the largely inaccessible underside of sea ice. We measured spectral under‐ice radiance and irradiance using the new Nereid Under‐Ice (NUI) underwater robotic vehicle, during a cruise of the R/V Polarstern to 83°N 6°W in the Arctic Ocean in July 2014. NUI is a next generation hybrid remotely operated vehicle (H‐ROV) designed for both remotely piloted and autonomous surveys underneath land‐fast and moving sea ice. Here we present results from one of the first comprehensive scientific dives of NUI employing its interdisciplinary sensor suite. We combine under‐ice optical measurements with three dimensional under‐ice topography (multibeam sonar) and aerial images of the surface conditions. We investigate the influence of spatially varying ice‐thickness and surface properties on the spatial variability of light transmittance during summer. Our results show that surface properties such as melt ponds dominate the spatial distribution of the under‐ice light field on small scales (<1000 m2), while sea ice‐thickness is the most important predictor for light transmission on larger scales. In addition, we propose the use of an algorithm to obtain histograms of light transmission from distributions of sea ice thickness and surface albedo. PMID:27660738

Influence of ice thickness and surface properties on light transmission through Arctic sea ice.

PubMed

Katlein, Christian; Arndt, Stefanie; Nicolaus, Marcel; Perovich, Donald K; Jakuba, Michael V; Suman, Stefano; Elliott, Stephen; Whitcomb, Louis L; McFarland, Christopher J; Gerdes, Rüdiger; Boetius, Antje; German, Christopher R

2015-09-01

The observed changes in physical properties of sea ice such as decreased thickness and increased melt pond cover severely impact the energy budget of Arctic sea ice. Increased light transmission leads to increased deposition of solar energy in the upper ocean and thus plays a crucial role for amount and timing of sea-ice-melt and under-ice primary production. Recent developments in underwater technology provide new opportunities to study light transmission below the largely inaccessible underside of sea ice. We measured spectral under-ice radiance and irradiance using the new Nereid Under-Ice (NUI) underwater robotic vehicle, during a cruise of the R/V Polarstern to 83°N 6°W in the Arctic Ocean in July 2014. NUI is a next generation hybrid remotely operated vehicle (H-ROV) designed for both remotely piloted and autonomous surveys underneath land-fast and moving sea ice. Here we present results from one of the first comprehensive scientific dives of NUI employing its interdisciplinary sensor suite. We combine under-ice optical measurements with three dimensional under-ice topography (multibeam sonar) and aerial images of the surface conditions. We investigate the influence of spatially varying ice-thickness and surface properties on the spatial variability of light transmittance during summer. Our results show that surface properties such as melt ponds dominate the spatial distribution of the under-ice light field on small scales (<1000 m 2 ), while sea ice-thickness is the most important predictor for light transmission on larger scales. In addition, we propose the use of an algorithm to obtain histograms of light transmission from distributions of sea ice thickness and surface albedo.

Regional variability in sea ice melt in a changing Arctic

PubMed Central

Perovich, Donald K.; Richter-Menge, Jacqueline A.

2015-01-01

In recent years, the Arctic sea ice cover has undergone a precipitous decline in summer extent. The sea ice mass balance integrates heat and provides insight on atmospheric and oceanic forcing. The amount of surface melt and bottom melt that occurs during the summer melt season was measured at 41 sites over the time period 1957 to 2014. There are large regional and temporal variations in both surface and bottom melting. Combined surface and bottom melt ranged from 16 to 294 cm, with a mean of 101 cm. The mean ice equivalent surface melt was 48 cm and the mean bottom melt was 53 cm. On average, surface melting decreases moving northward from the Beaufort Sea towards the North Pole; however interannual differences in atmospheric forcing can overwhelm the influence of latitude. Substantial increases in bottom melting are a major contributor to ice losses in the Beaufort Sea, due to decreases in ice concentration. In the central Arctic, surface and bottom melting demonstrate interannual variability, but show no strong temporal trends from 2000 to 2014. This suggests that under current conditions, summer melting in the central Arctic is not large enough to completely remove the sea ice cover. PMID:26032323

Cryosphere and climate

NASA Technical Reports Server (NTRS)

Hibler, William D., III; Thorndike, Alan S.

1992-01-01

This chapter will discuss two main issues related to the cryosphere and climate. One is the effect of sea ice and salinity gradients on ocean circulation, and in particular the possible role of sea ice transport on the ocean conveyer belt. The other is the effect of the cryosphere on climate, and in particular in high-latitude warming under increased CO2. In understanding the role of the cryosphere in both cases, it is useful to elucidate two types of toy sea ice models. Neither of these represents reality, but both are useful for illustrating the archetypal features of sea ice that control much of its large-scale behavior. The first model is a simple slab thermodynamic sea ice model as presented by Thorndike. In this model there are no dynamical effects and the thickness of ice is determined by surface heat budget and oceanic heat flux considerations, with the thickness of the ice critically affecting the effective conductivity whereby heat is transferred from the bottom ice boundary to the upper ice boundary. In this model all of the sea ice characteristics are controlled by the vertical heat fluxes from the atmosphere and ocean into the ice. The thickness is controlled by the ice's becoming an effective insulator as it thickens, thus reducing conductive heat loss to the atmosphere. A second model emphasizes the effects of dynamics. It considers the ice pack to be a collection of floes moving in response to synoptic wind fields and ocean currents. These motions create semipermanent leads (open areas) over which ice can grow rapidly.

Earth observations during STS-89

NASA Image and Video Library

1998-01-26

STS089-743-004 (22-31 Jan. 1998) --- This picture showing Auckland Island, New Zealand was photographed with a 70mm handheld camera from the Earth-orbiting space shuttle Endeavour. A spectacular occurrence of internal waves in the ocean is visible in the wake of the island. These waves can be generated by currents or, in some cases, wind across the island. In this case, the observation was that these waves were visible after the sunglint disappeared, suggesting current generated effects. If so, the circum-polar current that moves west-east around Antarctica would generate the scalloped appearance in the water east of the island. There is characteristically very little surface expression to these waves so they would not be noticed by a ship in this region. Fundamental processes of oceanic circulation and interaction are poorly understood. These shots help oceanographers model the dynamics of the open ocean and work out mixing models for ocean layer and ocean-air interaction (important for modeling CO2 budget, for example). The long linear valleys and bays have been excavated by glaciers cutting into this long-extinct volcano. This island is located on the submerged Campbell Plateau, which is an area almost as large as the exposed land of South Island, New Zealand. Scientists report that the plateau was submerged when New Zealand, Antarctica and Australia separated "around 75 million years ago." This could be viewed as one of the tallest mountains on the plateau. Usually the weather in this area is bad so this photo opportunity was considered a "great catch." Photo credit: NASA

Near grazing scattering from non-Gaussian ocean surfaces

NASA Technical Reports Server (NTRS)

Kim, Yunjin; Rodriguez, Ernesto

1993-01-01

We investigate the behavior of the scattered electromagnetic waves from non-Gaussian ocean surfaces at near grazing incidence. Even though the scattering mechanisms at moderate incidence angles are relatively well understood, the same is not true for near grazing rough surface scattering. However, from the experimental ocean scattering data, it has been observed that the backscattering cross section of a horizontally polarized wave can be as large as the vertical counterpart at near grazing incidence. In addition, these returns are highly intermittent in time. There have been some suggestions that these unexpected effects may come from shadowing or feature scattering. Using numerical scattering simulations, it can be shown that the horizontal backscattering cannot be larger than the vertical one for the Gaussian surfaces. Our main objective of this study is to gain a clear understanding of scattering mechanisms underlying the near grazing ocean scattering. In order to evaluate the backscattering cross section from ocean surfaces at near grazing incidence, both the hydrodynamic modeling of ocean surfaces and an accurate near grazing scattering theory are required. For the surface modeling, we generate Gaussian surfaces from the ocean surface power spectrum which is derived using several experimental data. Then, weakly nonlinear large scale ocean surfaces are generated following Longuet-Higgins. In addition, the modulation of small waves by large waves is included using the conservation of wave action. For surface scattering, we use MOM (Method of Moments) to calculate the backscattering from scattering patches with the two scale shadowing approximation. The differences between Gaussian and non-Gaussian surface scattering at near grazing incidence are presented.

Kinematics and segmentation of the South Shetland Islands-Bransfield basin system, northern Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Taylor, Frederick W.; Bevis, Michael G.; Dalziel, Ian W. D.; Smalley, Robert; Frohlich, Cliff; Kendrick, Eric; Foster, James; Phillips, David; Gudipati, Krishnavikas

2008-04-01

New GPS measurements demonstrate tectonic segmentation of the South Shetland Islands platform, regarded as a microplate separating the Antarctic Peninsula from the oceanic portion of the Antarctic plate. King George, Greenwich, and Livingston islands on the central and largest segment are separating from the Antarctic Peninsula at 7-9 mm/a, moving NNW, roughly perpendicular to the continental margin. Smith and Low islands on the small southwestern segment are moving in the same direction, but at 2.2-3.0 mm/a. The Elephant Island subgroup in the northeast moves at ˜7 mm/a relative to the Peninsula, like the central group, but toward the WNW. This implies that it is presently coupled to the Scotia plate on the northern side of the South Scotia Ridge transform boundary; thus the uplift of these northeasternmost islands may be caused by Scotia-Antarctic plate convergence rather than by subduction of thickened oceanic crust.

Toward a national animal telemetry network for aquatic observations in the United States

USGS Publications Warehouse

Block, Barbara A.; Holbrook, Christopher; Simmons, Samantha E; Holland, Kim N; Ault, Jerald S.; Costa, Daniel P.; Mate, Bruce R; Seitz, Andrew C.; Arendt, Michael D.; Payne, John; Mahmoudi, Behzad; Moore, Peter L.; Price, James; J. J. Levenson,; Wilson, Doug; Kochevar, Randall E

2016-01-01

Animal telemetry is the science of elucidating the movements and behavior of animals in relation to their environment or habitat. Here, we focus on telemetry of aquatic species (marine mammals, sharks, fish, sea birds and turtles) and so are concerned with animal movements and behavior as they move through and above the world’s oceans, coastal rivers, estuaries and great lakes. Animal telemetry devices (“tags”) yield detailed data regarding animal responses to the coupled ocean–atmosphere and physical environment through which they are moving. Animal telemetry has matured and we describe a developing US Animal Telemetry Network (ATN) observing system that monitors aquatic life on a range of temporal and spatial scales that will yield both short- and long-term benefits, fill oceanographic observing and knowledge gaps and advance many of the U.S. National Ocean Policy Priority Objectives. ATN has the potential to create a huge impact for the ocean observing activities undertaken by the U.S. Integrated Ocean Observing System (IOOS) and become a model for establishing additional national-level telemetry networks worldwide.

Arabian Sea as seen from STS-62

NASA Technical Reports Server (NTRS)

1994-01-01

The photo depicts many of the types of ocean features seen when illuminated by sunglint. These features include a shear line, bilge dump, currents, and ship wakes. Winds, currents and oils effect the smoothness of the surface of the water. The oils smooth the water which reflect the sun more than the rougher surrounding water. This is seen in the bright curved line which is a bilge dump of oily water from a ship. The oils then start to take the form of the currents and in this case are also being blown by the surface winds. The shear line is approximately 240 miles west of Bombay, India. This shear line appears to be a result of two water masses, moving at slightly different speeds, having converged. Ship wakes, such as those in the photo, which cross a shear line, often give us an indication of the relative strength of a shear.

Statistical Aspects of Tropical Cyclone Activity in the North Atlantic Basin, 1945-2010

NASA Technical Reports Server (NTRS)

Wilson, Robert M.

2012-01-01

Examined are statistical aspects of the 715 tropical cyclones that formed in the North Atlantic basin during the interval 1945-2010. These 715 tropical cyclones include 306 storms that attained only tropical storm strength, 409 hurricanes, 179 major or intense hurricanes, and 108 storms that struck the US coastline as hurricanes. Comparisons made using 10-year moving average (10-yma) values between tropical cyclone parametric values and surface air and ENSO-related parametric values indicate strong correlations to exist, in particular, against the Armagh Observatory (Northern Ireland) surface air temperature, the Atlantic Multi-decadal Oscillation (AMO) index, the Atlantic Meridional Mode (AMM) index, and the North Atlantic Oscillation (NAO) index, in addition to the Oceanic Ni o index (ONI) and Quasi-Biennial Oscillation (QBO) indices. Also examined are the decadal variations of the tropical cyclone parametric values and a look ahead towards the 2012 hurricane season and beyond.

TOPEX/El Nino Watch - October 23, 1997

NASA Technical Reports Server (NTRS)

1997-01-01

This image of the Pacific Ocean was produced using sea surface height measurements taken by the U.S./French TOPEX/POSEIDON satellite. The image shows sea surface height relative to normal ocean conditions on Oct. 23, 1997 as the warm water associated with El Nino (in white) spreads northward along the entire coast of North America from the equator all the way to Alaska. The warm water pool associated with the El Nino has returned to the volume it was in mid-September after dropping to a temporary low at the beginning of October. The sea surface elevation just north of the El Nino warm pool continues to drop (purple area), enhancing the eastward flowing North Equatorial Counter Current. The intensification of this current is another tell-tale sign of the El Nino phenomenon. This flow contributes to the rise in sea level along the western coasts of the Americas that will progress towards both the north and south poles over the next several months. The white and red areas indicate unusual patterns of heat storage; in the white areas, the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The surface area covered by the warm water mass is about one and one-half times the size of the continental United States. The added amount of oceanic warm water near the Americas, with a temperature between 21-30 degrees Celsius (70- 85 degrees Fahrenheit), is about 30 times the volume of water in all the U.S. Great Lakes combined. The green areas indicate normal conditions, while purple (the western Pacific) means at least 18 centimeters (7 inches) below normal sea level.

The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. Using these global data, limited regional measurements from buoys and ships, and a forecasting model of the ocean-atmosphere system, the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration, (NOAA), has issued an advisory indicating the presence of a strong El Nino condition throughout the winter.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov/

Surface flux and ocean heat transport convergence contributions to seasonal and interannual variations of ocean heat content

NASA Astrophysics Data System (ADS)

Roberts, C. D.; Palmer, M. D.; Allan, R. P.; Desbruyeres, D. G.; Hyder, P.; Liu, C.; Smith, D.

2017-01-01

We present an observation-based heat budget analysis for seasonal and interannual variations of ocean heat content (H) in the mixed layer (Hmld) and full-depth ocean (Htot). Surface heat flux and ocean heat content estimates are combined using a novel Kalman smoother-based method. Regional contributions from ocean heat transport convergences are inferred as a residual and the dominant drivers of Hmld and Htot are quantified for seasonal and interannual time scales. We find that non-Ekman ocean heat transport processes dominate Hmld variations in the equatorial oceans and regions of strong ocean currents and substantial eddy activity. In these locations, surface temperature anomalies generated by ocean dynamics result in turbulent flux anomalies that drive the overlying atmosphere. In addition, we find large regions of the Atlantic and Pacific oceans where heat transports combine with local air-sea fluxes to generate mixed layer temperature anomalies. In all locations, except regions of deep convection and water mass transformation, interannual variations in Htot are dominated by the internal rearrangement of heat by ocean dynamics rather than the loss or addition of heat at the surface. Our analysis suggests that, even in extratropical latitudes, initialization of ocean dynamical processes could be an important source of skill for interannual predictability of Hmld and Htot. Furthermore, we expect variations in Htot (and thus thermosteric sea level) to be more predictable than near surface temperature anomalies due to the increased importance of ocean heat transport processes for full-depth heat budgets.

Ocean Fertilization and Ocean Acidification

NASA Astrophysics Data System (ADS)

Cao, L.; Caldeira, K.

2008-12-01

It has been suggested that ocean fertilization could help diminish ocean acidification. Here, we quantitatively evaluate this suggestion. Ocean fertilization is one of several ocean methods proposed to mitigate atmospheric CO2 concentrations. The basic idea of this method is to enhance the biological uptake of atmospheric CO2 by stimulating net phytoplankton growth through the addition of iron to the surface ocean. Concern has been expressed that ocean fertilization may not be very effective at reducing atmospheric CO2 concentrations and may produce unintended environmental consequences. The rationale for thinking that ocean fertilization might help diminish ocean acidification is that dissolved inorganic carbon concentrations in the near-surface equilibrate with the atmosphere in about a year. If ocean fertilization could reduce atmospheric CO2 concentrations, it would also reduce surface ocean dissolved inorganic carbon concentrations, and thus diminish the degree of ocean acidification. To evaluate this line of thinking, we use a global ocean carbon cycle model with a simple representation of marine biology and investigate the maximum potential effect of ocean fertilization on ocean carbonate chemistry. We find that the effect of ocean fertilization on ocean acidification depends, in part, on the context in which ocean fertilization is performed. With fixed emissions of CO2 to the atmosphere, ocean fertilization moderately mitigates changes in ocean carbonate chemistry near the ocean surface, but at the expense of further acidifying the deep ocean. Under the SRES A2 CO2 emission scenario, by year 2100 simulated atmospheric CO2, global mean surface pH, and saturation state of aragonite is 965 ppm, 7.74, and 1.55 for the scenario without fertilization and 833 ppm, 7.80, and 1.71 for the scenario with 100-year (between 2000 and 2100) continuous fertilization for the global ocean (For comparison, pre-industrial global mean surface pH and saturation state of aragonite is 8.18 and 3.5). As a result of ocean fertilization, 10 years from now, the depth of saturation horizon (the depth below which ocean water is undersaturated with respect to calcium carbonate) for aragonite in the Southern Ocean shoals from its present average value of about 700 m to 100 m. In contrast, no significant change in the depth of aragonite saturation horizontal is seen in the scenario without fertilization for the corresponding period. By year 2100, global mean calcite saturation horizon shoals from its present value of 3150 m to 2965 and 2534 m in the case without fertilization and with it. In contrast, if the sale of carbon credits from ocean fertilization leads to greater CO2 emissions to the atmosphere (e.g., if carbon credits from ocean fertilization are used to offset CO2 emissions from a coal plant), then there is the potential that ocean fertilization would further acidify the deep ocean without conferring any chemical benefit to surface ocean waters.

High School's New Face

ERIC Educational Resources Information Center

Furger, Roberta

2004-01-01

No longer limited to the classroom, educators move to close the gap between school and the real world. Transforming high schools has been likened to turning an ocean liner around: It involves slow progress seemingly measured in inches, rather than yards or miles. This report discusses how educators move to close to gap between school and the real…

Ocean current surface measurement using dynamic elevations obtained by the GEOS-3 radar altimeter

NASA Technical Reports Server (NTRS)

Leitao, C. D.; Huang, N. E.; Parra, C. G.

1977-01-01

Remote Sensing of the ocean surface from the GEOS-3 satellite using radar altimeter data has confirmed that the altimeter can detect the dynamic ocean topographic elevations relative to an equipotential surface, thus resulting in a reliable direct measurement of the ocean surface. Maps of the ocean dynamic topography calculated over a one month period and with 20 cm contour interval are prepared for the last half of 1975. The Gulf Stream is observed by the rapid slope change shown by the crowding of contours. Cold eddies associated with the current are seen as roughly circular depressions.

Contents of the NASA ocean data system archive, version 11-90

NASA Technical Reports Server (NTRS)

Smith, Elizabeth A. (Editor); Lassanyi, Ruby A. (Editor)

1990-01-01

The National Aeronautics and Space Administration (NASA) Ocean Data System (NODS) archive at the Jet Propulsion Laboratory (JPL) includes satellite data sets for the ocean sciences and global-change research to facilitate multidisciplinary use of satellite ocean data. Parameters include sea-surface height, surface-wind vector, sea-surface temperature, atmospheric liquid water, and surface pigment concentration. NODS will become the Data Archive and Distribution Service of the JPL Distributed Active Archive Center for the Earth Observing System Data and Information System (EOSDIS) and will be the United States distribution site for Ocean Topography Experiment (TOPEX)/POSEIDON data and metadata.

Ocean Surface Topography Mission/Jason 2 Artist Concept

NASA Image and Video Library

2008-09-23

An artist concept of the Ocean Surface Topography Mission/Jason 2 Earth satellite. The Ocean Surface Topography Mission/Jason 2 is an Earth satellite designed to make observations of ocean topography for investigations into sea-level rise and the relationship between ocean circulation and climate change. The satellite also provides data on the forces behind such large-scale climate phenomena as El Niño and La Niña. The mission is a follow-on to the French-American Jason 1 mission, which began collecting data on sea-surface levels in 1992. http://photojournal.jpl.nasa.gov/catalog/PIA18158

Explanations for Temperature Increases in the Northern and Southern Atlantic Ocean are Proposed

NASA Astrophysics Data System (ADS)

Cimorelli, S. A.

2012-04-01

Primarily, consider some background hypotheses in the first paragraph: Three Types of mechanisms for Stellar Origin, Formation and Evolution are hypothesized. The first type (A) is well known; whereas, the other two (B&C) are new and proposed herein. The type A process, the presently universally accepted process, consists of the three phases of gravitation, followed by accretion, followed by fragmentation. In a Type B process, a star originates as an expanded, modified, category 3 Black Hole (BH) [1], with none or little help from gravitation/accretion, that begins to radiate, and continues to grow into a star. In a Type C process, a star would originate from a combination of the mechanisms described above for Type B and A. This mechanism, Type C, is perhaps the most common type. This type starts as an expanded, modified, category 3 BH inside of a gas and dust cloud. This then serves as the nucleus that starts the subsequent gravitation/accretion process; however, it greatly accelerates the accretion/formation process as in a standard Type A process. This mechanism could then explain how some super-cluster complexes, which have been estimated would take 40 to 60 billion years to form, can occur in a universe of a much younger age, i.e. 13.7 billion years. Also, consider that the ratio of the 'surface area to volume' is greater in a relatively smaller sphere; which would cause that smaller body of limited energy to cool off'/down, faster; however to continue to grow. A suggested sequence to explain why the Northern (South Greenland) and Southern Regions of the Atlantic Ocean are getting warmer is proposed: As the earth grows, two things occur, among others [1]. It is hypothesized the earth is expanding, circumferentially, about 3 cm per year at the equator (1 cm in the Atlantic, and 2 cm in the Pacific), rather than just 1 cm at the center of the Atlantic, as is commonly accepted. The earth may be expanding at an even greater rate, longitudinally (north and south), throughout the Pacific Ocean. The dozens/hundreds of horizontal (latitudinal) ridges/trenches, better known to some as stress relief cracks, in the Pacific Ocean (and Indian Ocean, etc.) Floor/Bed (over 30 prominent in the North and over 40 in the South) could be showing the effects of this. The most prominent, active stress relief crack, as it elongates, is helping and continuing to form the Hawaiian Islands. The movement north of the western coast of North America, is speculated to be a result of this oceanic longitudinal expansion. This effect is measurable in the northern hemisphere at the San Andreas Fault; and the effects are prominent in the earthquakes, especially on the western coast of South America, in the southern hemisphere. It is realized that fundamental tectonic plate movement also explains this very well; however it does not explain the driving forces, involved. If indeed, all of this is occurring, the masses, at each of the poles, would be moving toward a latitude with a greater angle relative to the equator while simultaneously, its distance to the equator remains constant. That is, the masses, at each of the poles, seem to move toward the Atlantic Ocean. As the angle of 'a surface to a hot body' is reduced, especially from above 60 degrees to below 60 degrees, noticeable effects occur. The end result would be for land masses, such as southern Greenland, to be at more southerly latitudes, facing the Sun at a lesser angle and absorbing more heat; thus explaining why it may be experiencing some global warming. Similarly, large ice masses in the northern coast of Antarctica, in the Atlantic Ocean, may also be moving toward more northerly latitudes, facing the Sun at a lesser angle, causing it to become warmer; and thus explaining why some glaciers are breaking off of the Antarctica, only on the Atlantic side. [1] A Hypothesis for the Origin and Evolution of Stars and Planets, Including Earth, which asks, "Was the Earth Once a Small Bright Star?" by S. A. Cimorelli and Dr. C. Samuels, American Geophysical Union, in Washington, DC, May 31, 2002.

Mapping Global Ocean Surface Albedo from Satellite Observations: Models, Algorithms, and Datasets

NASA Astrophysics Data System (ADS)

Li, X.; Fan, X.; Yan, H.; Li, A.; Wang, M.; Qu, Y.

2018-04-01

Ocean surface albedo (OSA) is one of the important parameters in surface radiation budget (SRB). It is usually considered as a controlling factor of the heat exchange among the atmosphere and ocean. The temporal and spatial dynamics of OSA determine the energy absorption of upper level ocean water, and have influences on the oceanic currents, atmospheric circulations, and transportation of material and energy of hydrosphere. Therefore, various parameterizations and models have been developed for describing the dynamics of OSA. However, it has been demonstrated that the currently available OSA datasets cannot full fill the requirement of global climate change studies. In this study, we present a literature review on mapping global OSA from satellite observations. The models (parameterizations, the coupled ocean-atmosphere radiative transfer (COART), and the three component ocean water albedo (TCOWA)), algorithms (the estimation method based on reanalysis data, and the direct-estimation algorithm), and datasets (the cloud, albedo and radiation (CLARA) surface albedo product, dataset derived by the TCOWA model, and the global land surface satellite (GLASS) phase-2 surface broadband albedo product) of OSA have been discussed, separately.

Measurements of Ocean Surface Scattering Using an Airborne 94-GHz Cloud Radar: Implication for Calibration of Airborne and Spaceborne W-band Radars

NASA Technical Reports Server (NTRS)

Li, Li-Hua; Heymsfield, Gerald M.; Tian, Lin; Racette, Paul E.

2004-01-01

Scattering properties of the Ocean surface have been widely used as a calibration reference for airborne and spaceborne microwave sensors. However, at millimeter-wave frequencies, the ocean surface backscattering mechanism is still not well understood, in part, due to the lack of experimental measurements. During the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE), measurements of ocean surface backscattering were made using a 94-GHz (W-band) cloud radar onboard a NASA ER-2 high-altitude aircraft. The measurement set includes the normalized Ocean surface cross section over a range of the incidence angles under a variety of wind conditions. Analysis of the radar measurements shows good agreement with a quasi-specular scattering model. This unprecedented dataset enhances our knowledge about the Ocean surface scattering mechanism at 94 GHz. The results of this work support the proposition of using the Ocean surface as a calibration reference for airborne millimeter-wave cloud radars and for the ongoing NASA CloudSat mission, which will use a 94-GHz spaceborne cloud radar for global cloud measurements.

Remote sensing of ocean surface currents: a review of what is being observed and what is being assimilated

NASA Astrophysics Data System (ADS)

Isern-Fontanet, Jordi; Ballabrera-Poy, Joaquim; Turiel, Antonio; García-Ladona, Emilio

2017-10-01

Ocean currents play a key role in Earth's climate - they impact almost any process taking place in the ocean and are of major importance for navigation and human activities at sea. Nevertheless, their observation and forecasting are still difficult. First, no observing system is able to provide direct measurements of global ocean currents on synoptic scales. Consequently, it has been necessary to use sea surface height and sea surface temperature measurements and refer to dynamical frameworks to derive the velocity field. Second, the assimilation of the velocity field into numerical models of ocean circulation is difficult mainly due to lack of data. Recent experiments that assimilate coastal-based radar data have shown that ocean currents will contribute to increasing the forecast skill of surface currents, but require application in multidata assimilation approaches to better identify the thermohaline structure of the ocean. In this paper we review the current knowledge in these fields and provide a global and systematic view of the technologies to retrieve ocean velocities in the upper ocean and the available approaches to assimilate this information into ocean models.

Mitigating Climate Change with Ocean Pipes: Influencing Land Temperature and Hydrology and Termination Overshoot Risk

NASA Astrophysics Data System (ADS)

Kwiatkowski, L.; Caldeira, K.; Ricke, K.

2014-12-01

With increasing risk of dangerous climate change geoengineering solutions to Earth's climate problems have attracted much attention. One proposed geoengineering approach considers the use of ocean pipes as a means to increase ocean carbon uptake and the storage of thermal energy in the deep ocean. We use a latest generation Earth System Model (ESM) to perform simulations of idealised extreme implementations of ocean pipes. In our simulations, downward transport of thermal energy by ocean pipes strongly cools the near surface atmosphere - by up to 11°C on a global mean. The ocean pipes cause net thermal energy to be transported from the terrestrial environment to the deep ocean while increasing the global net transport of water to land. By cooling the ocean surface more than the land, ocean pipes tend to promote a monsoonal-type circulation, resulting in increased water vapour transport to land. Throughout their implementation, ocean pipes prevent energy from escaping to space, increasing the amount of energy stored in Earth's climate system despite reductions in surface temperature. As a consequence, our results indicate that an abrupt termination of ocean pipes could cause dramatic increases in surface temperatures beyond that which would have been obtained had ocean pipes not been implemented.

75 FR 5708 - Ocean Dumping; Designation of Ocean Dredged Material Disposal Sites Offshore of the Siuslaw River...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-04

... suspended by wave action near the bottom, and are moved by bottom currents or directly as bedload. Tidal, wind and wave forces contribute to generating bottom currents, which act in relation to the sediment... littoral zone, limit wave effects due to mounding, and keep material from reentering the navigation channel...

The Gulf Stream and Density of Fluids

ERIC Educational Resources Information Center

Landstrom, Erich

2006-01-01

A few kilometers from the shores of Palm Beach County, Florida, is the Gulf Stream current--a remarkable "river" within an ocean. The current's journey across the Atlantic Ocean connects southeast Florida and southwest Great Britain as it streams steadily north at speeds of 97 km a day; moving 100 times as much water as all the rivers on…

The Future of the Pacific Basin: A Keynote Address.

ERIC Educational Resources Information Center

Cleveland, Harlan

People of the Pacific Basin must decide how to manage the Pacific Ocean commons, who does what in a changing industrial structure, and how to adapt to the new technological revolution. Although the United Nations' Law of the Sea moved into national jurisdiction many of the ocean resources of the Pacific Region, there is one new major…

Carbon speciation at the air-sea interface during rain

NASA Astrophysics Data System (ADS)

McGillis, Wade; Hsueh, Diana; Takeshita, Yui; Donham, Emily; Markowitz, Michele; Turk, Daniela; Martz, Todd; Price, Nicole; Langdon, Chris; Najjar, Raymond; Herrmann, Maria; Sutton, Adrienne; Loose, Brice; Paine, Julia; Zappa, Christopher

2015-04-01

This investigation demonstrates the surface ocean dilution during rain events on the ocean and quantifies the lowering of surface pCO2 affecting the air-sea exchange of carbon dioxide. Surface salinity was measured during rain events in Puerto Rico, the Florida Keys, East Coast USA, Panama, and the Palmyra Atoll. End-member analysis is used to determine the subsequent surface ocean carbonate speciation. Surface ocean carbonate chemistry was measured during rain events to verify any approximations made. The physical processes during rain (cold, fresh water intrusion and buoyancy, surface waves and shear, microscale mixing) are described. The role of rain on surface mixing, biogeochemistry, and air-sea gas exchange will be discussed.

Effects of Sea-Surface Waves and Ocean Spray on Air-Sea Momentum Fluxes

NASA Astrophysics Data System (ADS)

Zhang, Ting; Song, Jinbao

2018-04-01

The effects of sea-surface waves and ocean spray on the marine atmospheric boundary layer (MABL) at different wind speeds and wave ages were investigated. An MABL model was developed that introduces a wave-induced component and spray force to the total surface stress. The theoretical model solution was determined assuming the eddy viscosity coefficient varied linearly with height above the sea surface. The wave-induced component was evaluated using a directional wave spectrum and growth rate. Spray force was described using interactions between ocean-spray droplets and wind-velocity shear. Wind profiles and sea-surface drag coefficients were calculated for low to high wind speeds for wind-generated sea at different wave ages to examine surface-wave and ocean-spray effects on MABL momentum distribution. The theoretical solutions were compared with model solutions neglecting wave-induced stress and/or spray stress. Surface waves strongly affected near-surface wind profiles and sea-surface drag coefficients at low to moderate wind speeds. Drag coefficients and near-surface wind speeds were lower for young than for old waves. At high wind speeds, ocean-spray droplets produced by wind-tearing breaking-wave crests affected the MABL strongly in comparison with surface waves, implying that wave age affects the MABL only negligibly. Low drag coefficients at high wind caused by ocean-spray production increased turbulent stress in the sea-spray generation layer, accelerating near-sea-surface wind. Comparing the analytical drag coefficient values with laboratory measurements and field observations indicated that surface waves and ocean spray significantly affect the MABL at different wind speeds and wave ages.

Aquantis C-Plane Ocean Current Turbine Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fleming, Alex

The Aquantis 2.5 MW Ocean Current Generation Device technology developed by Dehlsen Associates, LLC (DA) is a derivation of wind power generating technology (a means of harnessing a slow moving fluid) adapted to the ocean environment. The Aquantis Project provides an opportunity for accelerated technological development and early commercialization, since it involves the joining of two mature disciplines: ocean engineering and wind turbine design. The Aquantis Current Plane (C-Plane) technology is an ocean current turbine designed to extract kinetic energy from a current flow. The technology is capable of achieving competitively priced, continuous, base-load, and reliable power generation from amore » source of renewable energy not before possible in this scale or form.« less

A Satellite View of Global Water and Energy Cycling

NASA Astrophysics Data System (ADS)

Houser, P. R.

2012-12-01

The global water cycle describes liquid, solid and vapor water dynamics as it moves through the atmosphere, oceans and land. Life exists because of water, and civilization depends on adapting to the constraints imposed by water availability. The carbon, water and energy cycles are strongly interdependent - energy is moved through evaporation and condensation, and photosynthesis is closely related to transpiration. There are significant knowledge gaps about water storage, fluxes and dynamics - we currently do not really know how much water is stored in snowpacks, groundwater or reservoirs. The view from space offers a vision for water science advancement. This vision includes observation, understanding, and prediction advancements that will improve water management and to inform water-related infrastructure that planning to provide for human needs and to protect the natural environment. The water cycle science challenge is to deploy a series of coordinated earth observation satellites, and to integrate in situ and space-borne observations to quantify the key water-cycle state variables and fluxes. The accompanying societal challenge is to integrate this information along with water cycle physics, and ecosystems and societal considerations as a basis for enlightened water resource management and to protect life and property from effects of water cycle extremes. Better regional to global scale water-cycle observations and predictions need to be readily available to reduce loss of life and property caused by water-related hazards. To this end, the NASA Energy and Water cycle Study (NEWS) has been documenting the satellite view of the water cycle with a goal of enabling improved, observationally based, predictions of water and energy cycle consequences of Earth system variability and change. NEWS has fostered broad interdisciplinary collaborations to study experimental and operational satellite observations and has developed analysis tools for characterizing air/sea fluxes, ocean circulation, atmospheric states, radiative balances, land surface states, sub-surface hydrology, snow and ice. This presentation will feature an overview of recent progress towards this challenge, and lay out the plan for coordination with complementary international efforts.

A wet-geology and cold-climate Mars model: Punctuation of a slow dynamic approach to equilibrium

NASA Technical Reports Server (NTRS)

Kargel, J. S.

1993-01-01

It was suggested that Mars may have possessed a relatively warm humid climate and a vigorous hydrological cycle involving meteoric precipitation, oceans, and continental ice sheets. Baker hypothesized that these geologically active conditions may have been repeated several times; each of these dynamic epochs was followed by a collapse of the climate and hydrologic cycle of Mars into essentially current conditions, completing what is termed a 'Baker cycle'. The purpose is to present an endmember possibility that Martian glacial landscapes, including some that were previously considered to have formed under warm climatic conditions, might be explained by processes compatible with an extremely cold surface. Two aspects of hypothesized Martian glacial terrains were cited as favoring a warm climate during Baker cycles: (1) the formation of some landscapes, including possible eskers, tunnel channels, drumlins, and outwash plains, appears to have required liquid water, and (2) a liquid-surfaced ocean was probably necessary to feed the glaciers. The requirement for liquid water, if these features were correctly interpreted, is difficult to avoid; it is entirely possible that a comparatively warm climate was involved, but it is not clear that formation of landforms by wet-based glaciers actually requires a warm climate. Even less certain is the supposed requirement for liquid oceans. Formation of glaciers only requires a source of water or ice to supply an amount of precipitation that exceeds losses due to melting and sublimation. At Martian temperatures precipitation is very low, but so are melting and sublimation, so a large body of ice that is unstable with respect to sublimation may take the role of Earth's oceans in feeding the glaciers. Recent models suggest that even current Martian polar caps, long thought to be static bodies of ice and dust, might actually be slow-moving, cryogenic continental glaciers. Is it possible that subglacial processes beneath cryogenic (but wetbased) ice sheets formed the hypothesized Martian glacial landscapes?

Evaluating the effect of oceanic striations on biogeochemistry in the eastern South Pacific

NASA Astrophysics Data System (ADS)

Auger, P. A.; Belmadani, A.; Donoso, D.; Hormazabal, S.

2017-12-01

In recent years, quasi-zonal mesoscale jet-like features or striations have been ubiquitously detected in the time-mean circulation of the world ocean using satellite altimetry and in situ data. Most likely the result of some organization of the mesoscale eddy field such as preferred eddy tracks, these striations may be able to advect and mix physical properties. Yet, their impact on biogeochemistry has not been assessed yet. Off central Chile, the interaction between striations and sharp background gradients of biogeochemical properties may spatially structure biogeochemistry, with potential implications for marine ecosystems. For instance, striations may affect the mean horizontal distribution of surface phytoplankton biomass in the coastal transition zone (CTZ), or the structure and variability of the oxygen-minimum zone (OMZ). Here, we evaluate the expression of striations in satellite records of ocean color and in a set of numerically simulated biogeochemical tracers off central Chile (chlorophyll, carbon, primary production, oxygen, nutrients), averaged over the surface productive layer, the OMZ at intermediate depths or the water column. A multi-decadal hindcast simulation of the physical-biogeochemical dynamics was run over the period 1984-2013 using the ROMS-PISCES (for Regional Oceanic Modeling System - Pelagic Interactions Scheme for Carbon and Ecosystem Studies) platform at an eddy-resolving resolution. Satellite data and model outputs are spatially high-pass filtered to remove the large-scale signal and evaluate the match between striations and biogeochemical tracer anomalies in the model and observations. The effect of striations on the mean shape of the zonal gradient of phytoplankton biomass in the CTZ between eutrophic coastal waters and oligotrophic offshore waters is then deduced. The fraction of tracer anomalies due to striations is quantified, and the structuring roles of stationary and transient striations are respectively explored by matching striations and biogeochemical tracers on moving frames of variable widths from 6 months to several years.

Latitudinal change in precipitation and water vapor isotopes over Southern ocean

NASA Astrophysics Data System (ADS)

Rahul, P.

2015-12-01

The evaporation process over ocean is primary source of water vapor in the hydrological cycle. The Global Network of Isotopes in Precipitation (GNIP) dataset of rainwater and water vapor isotopes are predominantly based on continental observations, with very limited observation available from the oceanic area. Stable isotope ratios in precipitation provide valuable means to understand the process of evaporation and transport of water vapor. This is further extended in the study of past changes in climate from the isotopic composition of ice core. In this study we present latitudinal variability of water vapor and rainwater isotopic composition and compared it with factors like physical condition of sea surface water from near equator (1°S) to the polar front (56°S) during the summer time expedition of the year 2013. The water vapor and rainwater isotopes showed a sharp depletion in isotopes while progressively move southward from the tropical regions (i.e. >30°S), which follows the pattern recorded in the surface ocean water isotopic composition. From the tropics to the southern latitudes, the water vapor d18O varied between -11.8‰ to -14.7‰ while dD variation ranges between -77.7‰ to -122.2‰. Using the data we estimated the expected water vapor isotopic composition under kinetic as well as equilibrium process. Our observation suggests that the water vapor isotopic compositions are in equilibrium with the sea water in majority of cases. At one point of observation, where trajectory of air parcel originated from the continental region, we observed a large deviation from the existing trend of latitudinal variability. The deduced rainwater composition adopting equilibrium model showed a consistent pattern with observed values at the tropical region, while role of kinetic process become dominant on progressive shift towards the southern latitudes. We will draw comparison of our observation with other data available in the literature together with isotope model data during the presentation.

The Influence of a Precursor Central American Gyre and a Northerly Surge into the Gulf of Tehuantepec on the Formation of Hurricane Patricia in October 2015

NASA Astrophysics Data System (ADS)

Bosart, L. F.; Bentley, A. M.; Levine, A. S.; Papin, P. P.

2016-12-01

The National Hurricane Center (NHC) initiated advisories on Tropical Depression (TD) Patricia at 1500 UTC 20 October 2015. Patricia originated from a pre-existing area of disturbed weather over the eastern Gulf of Tehuantepec (GoT) subsequent to the formation of a Central American gyre (CAG) and a surge of northerly gap flow across the Isthmus of Tehuantepec (Chivela Pass) and into the GoT. The gap flow was driven by strong low-level height rises over the northern Gulf of Mexico behind a southeastward-moving cold front. Low-level anticyclogenesis over the Gulf of Mexico and the southeastern United States behind the cold front and CAG-related surface pressure falls over Central America contributed to the development of an anomalously strong meridional surface pressure gradient that further sustained the aforementioned gap flow. An elongated strip of cyclonic shear vorticity formed along the eastern margin of the northerly gap flow over the GoT while oceanic heat and moisture fluxes maximized in the core of the strongest flow. Subsequently, this vorticity strip broke down into a cyclonic vortex shortly by 0000 UTC 20 October which prompted the National Hurricane Center to declare that tropical depression (TD) had formed near 13.4°N and 94.0°W by 0600 UTC 20 October. This TD was named tropical storm (TS) Patricia at 0000 UTC 21 October as the developing TS moved over a region of anomalously warm SSTs and high oceanic heat content in the presence of large oceanic heat and moisture fluxes. Northerly gap flow ceased and the CAG circulation broke down as a strengthening TS Patricia in the eastern Pacific crossed the longitude (95°W) of the Chivela Pass, leading to the cessation of northerly gap flow and the onset of strengthening southerly flow. Deep tropical moisture concentrated to the north and east of the now remnant CAG circulation center was advected northwestward into the western Gulf of Mexico where it supported very heavy rainfall in southeastern Texas. This sequence of CAG-related events, their likely importance to the genesis of TD Patricia, and the subsequent heavy rains in eastern Texas, much of Louisiana, and southwestern Arkansas will be illustrated.

Physical Climatology of Indonesian Maritime Continent: An Overview of Observational Studies

NASA Astrophysics Data System (ADS)

Yamanaka, M. D.

2014-12-01

The Indonesian maritime continent (IMC) is a miniature of our land-sea coexisting planet Earth. Firstly, without interior activity, the Earth becomes an even-surfaced "aqua-planet" with both atmosphere and ocean flowing almost zonally, and solar differential heating generates (global thermal tides and) Hadley's meridional circulations with ITCZ along the equator as observed actually over open (Indian and Pacific) oceans in the both sides of IMC. ITCZ involves intraseasonal variations or super cloud clusters moving eastward. Secondly, the lands and seas over the actual Earth have been keeping the area ratio of 3:7 (similar to that of islands and inland/surrounding seas in IMC), but their displacements have produced IMC near the equator, which turns equatorial Pacific easterly current northward (Kuroshio) and reflects equatorial oceanic waves inducing coupled ocean-atmosphere interannual variations such as ENSO and IOD, or displacements of Walker's zonal circulations. Thirdly, because IMC consists of many large/small islands with very long coastlines, many narrow straits become a dam for the global (Pacific to Indian) ocean circulation, and the land-sea heat capacity contrasts along the coastlines generate the world's largest rainfall with diurnal cycles (sea-land breeze circulations). The diurnal cycles are dominant in the rainy season (austral summer in Jawa and Bali), because rainfall-induced sprinkler-like land cooling reverses the trans-coastal temperature gradient before sunrise, and subsequent clear sky on land until around noon provides solar heating dependent on season. These processes lead to rapid land/hydrosphere-atmosphere water exchange, local air pollutant washout, and transequatorial boreal winter monsoon (cold surge). In El Niño years the cooler sea-surface temperature suppresses the morning coastal-sea rainfall, and induces often serious smog over IMC. Lastly, high-resolution observations/models covering both over islands and seas are necessary. A radar-profiler network (HARIMAU) has been constructed during FY2005-09, and capacity building on radar operations and buoy manufacturing has been promoted during FY2009-13 by Japan-Indonesia collaboration projects, which are taken over by an Indonesian national center (MCCOE) established in November 2013.

Visualizing characteristics of ocean data collected during the Shuttle Imaging Radar-B experiment

NASA Technical Reports Server (NTRS)

Tilley, David G.

1991-01-01

Topographic measurements of sea surface elevation collected by the Surface Contour Radar (SCR) during NASA's Shuttle Imaging Radar (SIR-B) experiment are plotted as three dimensional surface plots to observe wave height variance along the track of a P-3 aircraft. Ocean wave spectra were computed from rotating altimeter measurements acquired by the Radar Ocean Wave Spectrometer (ROWS). Fourier power spectra computed from SIR-B synthetic aperture radar (SAR) images of the ocean are compared to ROWS surface wave spectra. Fourier inversion of SAR spectra, after subtraction of spectral noise and modeling of wave height modulation, yields topography similar to direct measurements made by SCR. Visual perspectives on the SCR and SAR ocean data are compared. Threshold distinctions between surface elevation and texture modulations of SAR data are considered within the context of a dynamic statistical model of rough surface scattering. The result of these endeavors is insight as to the physical mechanism governing the imaging of ocean waves with SAR.

Closing the Seasonal Ocean Surface Temperature Balance in the Eastern Tropical Oceans from Remote Sensing and Model Reanalyses

NASA Technical Reports Server (NTRS)

Roberts, J. Brent; Clayson, C. A.

2012-01-01

Residual forcing necessary to close the MLTB on seasonal time scales are largest in regions of strongest surface heat flux forcing. Identifying the dominant source of error - surface heat flux error, mixed layer depth estimation, ocean dynamical forcing - remains a challenge in the eastern tropical oceans where ocean processes are very active. Improved sub-surface observations are necessary to better constrain errors. 1. Mixed layer depth evolution is critical to the seasonal evolution of mixed layer temperatures. It determines the inertia of the mixed layer, and scales the sensitivity of the MLTB to errors in surface heat flux and ocean dynamical forcing. This role produces timing impacts for errors in SST prediction. 2. Errors in the MLTB are larger than the historical 10Wm-2 target accuracy. In some regions, a larger accuracy can be tolerated if the goal is to resolve the seasonal SST cycle.

Seasat--A 25-Year Legacy of Success

NASA Technical Reports Server (NTRS)

Evans, Diane L.; Alpers, Werner; Cazenave, Anny; Elachi, Charles; Farr, Tom; Glackin, David; Holt, Benjamin; Jones, Linwood; Liu, W. Timothy; McCandless, Walt;

Exploring the southern ocean response to climate change

NASA Technical Reports Server (NTRS)

Martinson, Douglas G.; Rind, David; Parkinson, Claire

1993-01-01

The purpose of this project was to couple a regional (Southern Ocean) ocean/sea ice model to the existing Goddard Institute for Space Science (GISS) atmospheric general circulation model (GCM). This modification recognizes: the relative isolation of the Southern Ocean; the need to account, prognostically, for the significant air/sea/ice interaction through all involved components; and the advantage of translating the atmospheric lower boundary (typically the rapidly changing ocean surface) to a level that is consistent with the physical response times governing the system evolution (that is, to the base of the fast responding ocean surface layer). The deeper ocean beneath this layer varies on time scales several orders of magnitude slower than the atmosphere and surface ocean, and therefore the boundary between the upper and deep ocean represents a more reasonable fixed boundary condition.

Interbasin effects of the Indian Ocean on Pacific decadal climate change

NASA Astrophysics Data System (ADS)

Mochizuki, Takashi; Kimoto, Masahide; Watanabe, Masahiro; Chikamoto, Yoshimitsu; Ishii, Masayoshi

2016-07-01

We demonstrate the significant impact of the Indian Ocean on the Pacific climate on decadal timescales by comparing two sets of data assimilation experiments (pacemaker experiments) conducted over recent decades. For the Indian Ocean of an atmosphere-ocean coupled global climate model, we assimilate ocean temperature and salinity anomalies defined as deviations from climatology or as anomalies with the area-averaged changes for the Indian Ocean subtracted. When decadal sea surface temperature (SST) trends are observed to be strong over the Indian Ocean, the equatorial thermocline uniformly deepens, and the model simulates the eastward tendencies of surface wind aloft. Surface winds strongly converge around the maritime continent, and the associated strengthening of the Walker circulation suppresses an increasing trend in the equatorial Pacific SST through ocean thermocline shoaling, similar to common changes associated with seasonal Indian Ocean warming.

Recent distribution of lead in the Indian Ocean reflects the impact of regional emissions.

PubMed

Echegoyen, Yolanda; Boyle, Edward A; Lee, Jong-Mi; Gamo, Toshitaka; Obata, Hajime; Norisuye, Kazuhiro

2014-10-28

Humans have injected lead (Pb) massively into the earth surface environment in a temporally and spatially evolving pattern. A significant fraction is transported by the atmosphere into the surface ocean where we can observe its transport by ocean currents and sinking particles. This study of the Indian Ocean documents high Pb concentrations in the northern and tropical surface waters and extremely low Pb levels in the deep water. North of 20°S, dissolved Pb concentrations decrease from 42 to 82 pmol/kg in surface waters to 1.5-3.3 pmol/kg in deep waters. South of 20°S, surface water Pb concentrations decrease from 21 pmol/kg at 31°S to 7 pmol/kg at 62°S. This surface Pb concentration gradient reflects a southward decrease in anthropogenic Pb emissions. The upper waters of the north and central Indian Ocean have high Pb concentrations resulting from recent regional rapid industrialization and a late phase-out of leaded gasoline, and these concentrations are now higher than currently seen in the central North Pacific and North Atlantic oceans. The Antarctic sector of the Indian Ocean shows very low concentrations due to limited regional anthropogenic Pb emissions, high scavenging rates, and rapid vertical mixing, but Pb still occurs at higher levels than would have existed centuries ago. Penetration of Pb into the northern and central Indian Ocean thermocline waters is minimized by limited ventilation. Pb concentrations in the deep Indian Ocean are comparable to the other oceans at the same latitude, and deep waters of the central Indian Ocean match the lowest observed oceanic Pb concentrations.

Improving NOAA's NWLON Through Enhanced Data Inputs from NASA's Ocean Surface Topography

NASA Technical Reports Server (NTRS)

Guest, DeNeice C.

2010-01-01

This report assesses the benefit of incorporating NASA's OSTM (Ocean Surface Topography Mission) altimeter data (C- and Ku-band) into NOAA's (National Oceanic and Atmospheric Administration) NWLON (National Water Level Observation Network) DSS (Decision Support System). This data will enhance the NWLON DSS by providing additional inforrnation because not all stations collect all meteorological parameters (sea-surface height, ocean tides, wave height, and wind speed over waves). OSTM will also provide data where NWLON stations are not present. OSTM will provide data on seasurface heights for determining sea-level rise and ocean circulation. Researchers and operational users currently use satellite altimeter data products with the GSFCOO NASA data model to obtain sea-surface height and ocean circulation inforrnation. Accurate and tirnely inforrnation concerning sea-level height, tide, and ocean currents is needed to irnprove coastal tidal predictions, tsunarni and storm surge warnings, and wetland restoration.

Multivariate optimum interpolation of surface pressure and winds over oceans

NASA Technical Reports Server (NTRS)

Bloom, S. C.

1984-01-01

The observations of surface pressure are quite sparse over oceanic areas. An effort to improve the analysis of surface pressure over oceans through the development of a multivariate surface analysis scheme which makes use of surface pressure and wind data is discussed. Although the present research used ship winds, future versions of this analysis scheme could utilize winds from additional sources, such as satellite scatterometer data.

Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

NASA Technical Reports Server (NTRS)

Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.; Houston, S. H.; Powell, M. D.; Black, P. G.; Marks, F. D.; Busalacchi, Antonio J. (Technical Monitor)

2000-01-01

The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1 E half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the incidence angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two-dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving slowly to the north. Individual waves with heights up to 18 m were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the hurricane Bonnie eye, and made five eye penetrations. A 3-minute animation of the directional wave spectrum spatial variation over this period will be shown as well as summary plots of the wave field spatial variation. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track included both segments along the shoreline and Pamlico Sound as well as far offshore. An animation of the directional wave spectrum spatial variation at landfall will be presented and contrasted with the spatial variation when Bonnie was in the open ocean on 24 August 1998.

Ocean heat budget analysis on sea surface temperature anomaly in western Indian Ocean during strong-weak Asian summer monsoon

NASA Astrophysics Data System (ADS)

Fathrio, Ibnu; Manda, Atsuyoshi; Iizuka, Satoshi; Kodama, Yasu-Masa; Ishida, Sachinobu

2018-05-01

This study presents ocean heat budget analysis on seas surface temperature (SST) anomalies during strong-weak Asian summer monsoon (southwest monsoon). As discussed by previous studies, there was close relationship between variations of Asian summer monsoon and SST anomaly in western Indian Ocean. In this study we utilized ocean heat budget analysis to elucidate the dominant mechanism that is responsible for generating SST anomaly during weak-strong boreal summer monsoon. Our results showed ocean advection plays more important role to initate SST anomaly than the atmospheric prcess (surface heat flux). Scatterplot analysis showed that vertical advection initiated SST anomaly in western Arabian Sea and southwestern Indian Ocean, while zonal advection initiated SST anomaly in western equatorial Indian Ocean.

Seasonal characteristics of water exchange in Beibu Gulf based on a particle tracking model

NASA Astrophysics Data System (ADS)

Wang, L.; Pan, W.; Yan, X.

2016-12-01

A lagrangian particle tracking model coupled with a three-dimensional Marine Environmental Committee Ocean Model (MEC) is used to study the transport and seasonal characteristics of water exchange in Beibu Gulf. The hydrodynamic model (MEC), which is forced with the daily surface and lateral boundary fluxes, as well as tidal harmonics and monthly climatological river discharges, is applied to simulate the flow field in the gulf during 2014. Using these results, particle tracking method which includes tidal advection and random walk in the horizontal is used to determine the residence times of sub regions within the gulf in response of winter and summer wind forcing. The result shows water exchange processes in the gulf have a similar tendency with seasonal circulation structure. During the sourthwestly prevailing wind in summer, water particles are traped within the gulf that considerably increases the residence time of each sub region. On the contrary, the presence of strong northeastly prevailing wind in winter drives particles to move cyclonicly leading to shorter residence times and rather active water exchanges among sub regions. Similarly, particle tracking is applied to investigate the water transport in Beibu Gulf. As Qiongzhou Strait and the wide opening in the south of the gulf are two significant channels connecting with the open ocean, continuous particle releases are simulated to quantify the influence range and the pathways of these sources water flowing into Beibu Gulf. The results show that water particles originated from Qiongzhou Strait are moving westward due to the year-round strong westward flow transportation. Influencing range in the north of the Beibu Gulf is enlarged by winter northeastly wind, however, it is blocked to the Leizhou Peninsula coastal region by summer westly wind. In the south opening, water particles are transported northward into the gulf along Hainan Island and flushed from Vietnam coastal region to the ocean rapidly by the longshore currents.

A Vision for the Next Ten Years for Integrated Ocean Observing Data

NASA Astrophysics Data System (ADS)

Willis, Z. S.

2012-12-01

Ocean observing has come a long way since the Ocean Sciences Decadal Committee met over a decade ago. Since then, our use of the ocean and coast and their vast resources has increased substantially - with increased shipping, fishing, offshore energy development and recreational boating. That increased use has also spearheaded advances in observing systems. Cutting-edge autonomous and remotely operated vehicles scour the surface and travel to depths collecting essential biogeochemical data for better managing our marine resources. Satellites enable the global mapping of practically every physical ocean variable imaginable. A nationally-integrated coastal network of high-frequency radars lines the borders of the U.S. feeding critical navigation, response, and environmental information continuously. Federal, academic, and industry communities have joined in unique partnerships at regional, national, and global levels to address common challenges to monitoring our ocean. The 2002 Workshop, Building Consensus: Toward an Integrated and Sustained Ocean Observing System laid the framework for the current United States Integrated Ocean Observing System (U.S. IOOS). Ten years later, U.S. IOOS has moved from concept to reality, though much work remains to meet the nation's ocean observing needs. Today, new research and technologies, evolving users and user requirements, economic and funding challenges, and diverse institutional mandates all influence the future growth and implementation of U.S. IOOS. In light of this new environment, the Interagency Ocean Observation Committee (IOOC) will host the 2012 Integrated Ocean Observing System Summit in November 2012, providing a forum to develop a comprehensive ocean observing vision for the next decade, utilizing the knowledge and expertise gained by the IOOS-wide community over the past ten years. This effort to bring together ocean observing stakeholders at the regional, national, and global levels to address these challenges going forward: - Enhancing information delivery and integration to save lives, enhance the economy and protect the environment - Disseminating seamless information across regional and national boundaries - Harnessing technological innovations for new frontiers and opportunities The anticipated outcomes of the IOOS Summit include a highlight of the past decade of progress towards an integrated system, revisiting and updating user requirements, an assessment of existing observing system capabilities and gaps, identifying integration challenges/opportunities, and, establishing an U.S. IOOS-community-wide vision for the next 10 years of ocean observing. Most important will be the execution of priorities identified before and during the Summit, carrying them forward into a new decade of an enhanced Integrated and Sustained Ocean Observing System.

Plate tectonic reconstruction of South and East Asia since 43 Ma using seismic tomographic constraints: role of the subducted ';East Asia Sea' (Invited)

NASA Astrophysics Data System (ADS)

Wu, J. E.; Suppe, J.; Renqi, L.; Kanda, R. V.

2013-12-01

Lithosphere that subducts at convergent plate boundaries provides a potentially decipherable plate tectonic record. In this study we use global seismic tomography to map subducted slabs in the upper and lower mantle under South and East Asia to constrain plate reconstructions. The mapped slabs include the Pacific, the Indian Ocean and Banda Sea, the Molucca Sea, Celebes Sea, the Philippine Sea and Eurasia, New Guinea and other lower mantle detached slabs. The mapped slabs were restored to the earth surface and used with Gplates software to constrain a globally-consistent, fully animated plate reconstruction of South and East Asia. Three principal slab elements dominate possible plate reconstructions: [1] The mapped Pacific slabs near the Izu-Bonin and the Marianas trenches form a subvertical slab curtain or wall extending down to 1500 km in the lower mantle. The ';slab curtain' geometry and restored slabs lengths indicate that the Pacific subduction zone has remained fixed within +/- 250 km of its present position since ~43 Ma. In contrast, the Tonga Pacific slab curtain records at least 1000 km trench rollback associated with expansion of back-arc basins. [2] West of the Pacific slab curtain, a set of flat slabs exist in the lower mantle and record a major 8000km by 2500-3000km ocean that existed at ~43 Ma. This now-subducted ocean, which we call the ';East Asian Sea', existed between the Ryukyu Asian margin and the Lord Howe hotspot, present-day eastern Australia, and fills a major gap in Cenozoic plate reconstructions between Indo-Australia, the Pacific Ocean and Asia. [3] An observed ';picture puzzle' fit between the restored edges of the Philippine Sea, Molucca Sea and Indian Ocean slabs suggests that the Philippine Sea was once part of a larger Indo-Australian Ocean. Previous models of Philippine Sea plate motions are in conflict with the location of the East Asian Sea lithosphere. Using the mapped slab constraints, we propose the following 43 Ma to 0 plate tectonic reconstruction. At ~43 Ma a major plate reorganization occurred in South and East Asia marked by Indian Ocean Wharton ridge extinction, initiation of Pacific Ocean WNW motions and the rapid northward motion of the Australian plate. The Philippine Sea and Molucca Sea were clustered at the northern margin of Australia, northwest of New Guinea. During the mid-Cenozoic these plates moved NNE with Australia, accommodated by N-S transforms at the eastern margin of Sundaland. The East Asian Sea was subducted under the northward-moving Philippine Sea and Australia plates, and the expanding Melanesian and Shikoku-Parece Vela backarc basins. At ~20 to 25 Ma the Philippine Sea and Molucca Sea were fragmented from Indo-Australia and began to have a westward component of motion due to partial Pacific capture. Around 1-2 Ma the Philippine Sea was more fully captured by the Pacific and now has rapid Pacific-like northwestward motions.

Novel Thermal Powered Technology for UUV Persistent Surveillance

NASA Technical Reports Server (NTRS)

Jones, Jack A.; Chao, Yi

2006-01-01

Buoyancy Generation: Various technology attempts include melting a wax, which pushes directly against a piston (U.S. Patent 5,291,847) or against a bladder (Webb Research), using ammonia or Freon 21 (U.S. Patent 5,303,552), and using solar heat to expand an oil (www.space.com, April, 10, 2002). All these heat-activated buoyancy control designs have thus far proved impractical and have ultimately failed during repeated cycling in ocean testing. JPL has demonstrated fully reversible 10 C encapsulated wax phase change, which can be used to change buoyancy without electrical hydraulic pumps. This technique has greatly improved heat transfer and much better reversibility than previous designs. Power Generation: Ocean Thermal Energy Conversion (OTEC) systems have been designed that transfer deep, cold sea water to the surface to generate electricity using turbine cycles with ammonia or water as the working fluid. JPL has designed several UUV systems: 1) Using a propeller water turbine to generate power on a gliding submersible; 2) Employing a compact CO2 turbine cycle powered by moving through thermoclines; and 3) Using melted wax to directly produce power through a piston-geared generator.

Large-Scale and Global Hydrology. Chapter 92

NASA Technical Reports Server (NTRS)

Rodell, Matthew; Beaudoing, Hiroko Kato; Koster, Randal; Peters-Lidard, Christa D.; Famiglietti, James S.; Lakshmi, Venkat

2016-01-01

Powered by the sun, water moves continuously between and through Earths oceanic, atmospheric, and terrestrial reservoirs. It enables life, shapes Earths surface, and responds to and influences climate change. Scientists measure various features of the water cycle using a combination of ground, airborne, and space-based observations, and seek to characterize it at multiple scales with the aid of numerical models. Over time our understanding of the water cycle and ability to quantify it have improved, owing to advances in observational capabilities, the extension of the data record, and increases in computing power and storage. Here we present some of the most recent estimates of global and continental ocean basin scale water cycle stocks and fluxes and provide examples of modern numerical modeling systems and reanalyses.Further, we discuss prospects for predicting water cycle variability at seasonal and longer scales, which is complicated by a changing climate and direct human impacts related to water management and agriculture. Changes to the water cycle will be among the most obvious and important facets of climate change, thus it is crucial that we continue to invest in our ability to monitor it.

The Bidirectional Reflectance Distribution Function (BRDF) of the Ocean: Effects of Wave Representation

NASA Astrophysics Data System (ADS)

Eide, H.; Stamnes, K.; Ottaviani, M.

2004-12-01

The specular reflection of the Sun off the ocean, or sun glint, is of major concern for ocean remote sensing. Typically, data from in and around the sunglint region are discarded because of the unknown contribution to the measured radiances or because of sensor saturation. On the other hand, accurate knowledge of the sunglint properties enables retrievals of atmospheric parameters. The challenge of the ocean retrieval problem is to get the ``water leaving radiance'', Lw, by subtracting the Rayleigh scattering, aerosol scattering, water vapor, ozone, and sun glint from the measured radiances at the top of the atmosphere (TOA). Thus, the task is to correct for both the atmospheric contribution and for surface effects. Two simplifying assumptions that are frequently employed in ocean remote sensing are that the ocean BRDF is isotropic and that one can de-couple the radiative properties of the atmosphere from those of the surface. Our previous studies have shown that neglecting the inherit coupling between the atmosphere and surface can lead to large errors in the retrievals. In order to do retrievals over bright, as well as darker surfaces, it is necessary to account for this coupling between the surface and the atmosphere. In the present study we use models for the reflection of light off the ocean surface to calculate the ocean BRDF. The differences between the various models are investigated as is the effect of using different types of wave statistics (e.g. Cox Munk). We present results from calculations where we vary the wind speed and direction as well as other parameters affecting the ocean surface. The error introduced in ocean retrievals by assuming an isotropic BRDF is assessed, and methods for improved treatment of sunglint are suggested.

Evaluation of the MODIS Aerosol Retrievals over Ocean and Land during CLAMS.

NASA Astrophysics Data System (ADS)

Levy, R. C.; Remer, L. A.; Martins, J. V.; Kaufman, Y. J.; Plana-Fattori, A.; Redemann, J.; Wenny, B.

2005-04-01

The Chesapeake Lighthouse Aircraft Measurements for Satellites (CLAMS) experiment took place from 10 July to 2 August 2001 in a combined ocean-land region that included the Chesapeake Lighthouse [Clouds and the Earth's Radiant Energy System (CERES) Ocean Validation Experiment (COVE)] and the Wallops Flight Facility (WFF), both along coastal Virginia. This experiment was designed mainly for validating instruments and algorithms aboard the Terra satellite platform, including the Moderate Resolution Imaging Spectroradiometer (MODIS). Over the ocean, MODIS retrieved aerosol optical depths (AODs) at seven wavelengths and an estimate of the aerosol size distribution. Over the land, MODIS retrieved AOD at three wavelengths plus qualitative estimates of the aerosol size. Temporally coincident measurements of aerosol properties were made with a variety of sun photometers from ground sites and airborne sites just above the surface. The set of sun photometers provided unprecedented spectral coverage from visible (VIS) to the solar near-infrared (NIR) and infrared (IR) wavelengths. In this study, AOD and aerosol size retrieved from MODIS is compared with similar measurements from the sun photometers. Over the nearby ocean, the MODIS AOD in the VIS and NIR correlated well with sun-photometer measurements, nearly fitting a one-to-one line on a scatterplot. As one moves from ocean to land, there is a pronounced discontinuity of the MODIS AOD, where MODIS compares poorly to the sun-photometer measurements. Especially in the blue wavelength, MODIS AOD is too high in clean aerosol conditions and too low under larger aerosol loadings. Using the Second Simulation of the Satellite Signal in the Solar Spectrum (6S) radiative code to perform atmospheric correction, the authors find inconsistency in the surface albedo assumptions used by the MODIS lookup tables. It is demonstrated how the high bias at low aerosol loadings can be corrected. By using updated urban/industrial aerosol climatology for the MODIS lookup table over land, it is shown that the low bias for larger aerosol loadings can also be corrected. Understanding and improving MODIS retrievals over the East Coast may point to strategies for correction in other locations, thus improving the global quality of MODIS. Improvements in regional aerosol detection could also lead to the use of MODIS for monitoring air pollution.

TOPEX/El Nino Watch - Satellite Shows Pacific Running Hot and Cold, September 12, 1998

NASA Technical Reports Server (NTRS)

1998-01-01

This image of the Pacific Ocean was produced using sea-surface height measurements taken by the U.S.-French TOPEX/Poseidon satellite. The image shows sea surface height relative to normal ocean conditions on September 12, 1998; these sea surface heights are an indicator of the changing amount of heat stored in the ocean. The tropical Pacific Ocean continues to exhibit the complicated characteristics of both a lingering El Nino, and a possibly waning La Nina situation. This image shows that the rapid cooling of the central tropical Pacific has slowed and this area of low sea level (shown in purple) has decreased slightly since last month. It is still uncertain, scientists say, that this cold pool will evolve into a long-lasting La Nina situation. Remnants of the El Nino warm water pool, shown here in red and white, are still lingering to the north and south of the equator. The coexistence of these two contrasting conditions indicates that the ocean and the climate system remain in transition. These strong patterns have remained in the climate system for many months and will continue to influence weather conditions around the world in the coming fall and winter. The satellite's sea-surface height measurements have provided scientists with a detailed view of the 1997-98 El Nino because the TOPEX/Poseidon satellite measures the changing sea-surface height with unprecedented precision. The purple areas are about 18 centimeters (7 inches) below normal, creating a deficit in the heat supply to the surface waters. The white areas show the sea surface is between 14 and 32 centimeters (6 to 13 inches) above normal; in the red areas, it's about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions. The purple areas are 14 to 18 centimeters (6 to 7 inches) below normal and the blue areas are 5 to 13 centimeters (2 to 5 inches) below normal. The El Nino phenomenon is thought to be triggered when the steady westward blowing trade winds weaken and even reverse direction. This change in the winds allows a large mass of warm water (the red and white area) that is normally located near Australia to move eastward along the equator until it reaches the coast of South America. The displacement of so much warm water affects evaporation, where rain clouds form and, consequently, alters the typical atmospheric jet stream patterns around the world. A La Nina situation is essentially the opposite of an El Nino condition, but during La Nina the trade winds are stronger than normal and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. A La Nina situation also changes global weather patterns, and is associated with less moisture in the air resulting in less rain along the west coasts of North and South America.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov

Local atmospheric response to warm mesoscale ocean eddies in the Kuroshio-Oyashio Confluence region.

PubMed

Sugimoto, Shusaku; Aono, Kenji; Fukui, Shin

2017-09-19

In the extratropical regions, surface winds enhance upward heat release from the ocean to atmosphere, resulting in cold surface ocean: surface ocean temperature is negatively correlated with upward heat flux. However, in the western boundary currents and eddy-rich regions, the warmer surface waters compared to surrounding waters enhance upward heat release-a positive correlation between upward heat release and surface ocean temperature, implying that the ocean drives the atmosphere. The atmospheric response to warm mesoscale ocean eddies with a horizontal extent of a few hundred kilometers remains unclear because of a lack of observations. By conducting regional atmospheric model experiments, we show that, in the Kuroshio-Oyashio Confluence region, wintertime warm eddies heat the marine atmospheric boundary layer (MABL), and accelerate westerly winds in the near-surface atmosphere via the vertical mixing effect, leading to wind convergence around the eastern edge of eddies. The warm-eddy-induced convergence forms local ascending motion where convective precipitation is enhanced, providing diabatic heating to the atmosphere above MABL. Our results indicate that warm eddies affect not only near-surface atmosphere but also free atmosphere, and possibly synoptic atmospheric variability. A detailed understanding of warm eddy-atmosphere interaction is necessary to improve in weather and climate projections.

Plausible surface models for Titan

NASA Technical Reports Server (NTRS)

Lunine, Jonathan I.

1992-01-01

Current understanding of the nature of Titan's surface and some new ideas for explaining the curious radar returns from Saturn's largest satellite are reviewed. Pre-Voyager models of the surface, based largely on cosmochemistry and the discovery of atmospheric methane, allowed for a range of possibilities, including pure methane oceans. The Voyager 1 flyby ruled out this last possibility, replacing it with compelling observational arguments in favor of a mixed light hydrocarbon and nitrogen ocean. Ground based radar observations indicated a surprisingly reflective surface which is inconsistent with a hydrocarbon ocean and more reminiscent of the Galilean Satellites. Nonetheless, passive radiometric measurements of the surface do not support the notion that Titan's surface is like that of the Galilean satellites. One of the arguments against hydrocarbon oceans reflecting radar energy is that most solid, complex hydrocarbon and nitriles will be denser than the liquid and sink. Nonetheless, many of the aerosol species will coagulate in highly nonspherical patterns, and some species probably polymerize in long chains. Such chains will have very low sedimendation velocities in the ocean and may remain near the surface through ocean mixing process. The prospect of an oceanic 'soup' of polar polymers acting as volume reflectors at radio wevelengths suggests that the interpretation of radar observations needs evaluation.

Influence of Typhoon Matsa on Phytoplankton Chlorophyll-a off East China

PubMed Central

Shao, Jinchao; Han, Guoqi; Yang, Dezhou

2015-01-01

Typhoons can cause strong disturbance, mixing, and upwelling in the upper layer of the oceans. Rich nutrients from the subsurface layer can be brought to the euphotic layer, which will induce the phytoplankton to breed and grow rapidly. In this paper, we investigate the impact of an intense and fast moving tropical storm, Typhoon Matsa, on phytoplankton chlorophyll-a (Chl-a) concentration off East China. By using satellite remote sensing data, we analyze the changes of Chl-a concentration, Sea Surface Temperature (SST) and wind speed in the pre- and post-typhoon periods. We also give a preliminary discussion on the different responses of the Chl-a concentration between nearshore and offshore waters. In nearshore/coastal regions where nutrients are generally rich, the Chl-a maximum occurs usually at the surface or at the layer close to the surface. And, in offshore tropical oligotrophic oceans, the subsurface maxima of Chl-a exist usually in the stratified water column. In an offshore area east of Taiwan, the Chl-a concentration rose gradually in about two weeks after the typhoon. However, in a coastal area north of Taiwan high Chl-a concentration decreased sharply before landfall, rebounded quickly to some degree after landfall, and restored gradually to the pre-typhoon level in about two weeks. The Chl-a concentration presented a negative correlation with the wind speed in the nearshore area during the typhoon, which is opposite to the response in the offshore waters. The phenomena may be attributable to onshore advection of low Chl-a water, coastal downwelling and intensified mixing, which together bring pre-typhoon surface Chl-a downward in the coastal area. In the offshore area, the typhoon may trigger increase of Chl-a concentration through uptake of nutrients by typhoon-induced upwelling and entrainment mixing. PMID:26407324

Earth: Physico-mathematical Meaning of "primary" and "secondary" Oceans Conception

NASA Astrophysics Data System (ADS)

Kochemasov, G.

Geologists term the Pacific ocean "primary" and Atlantic and Indian oceans "sec- ondary" meaning that the first is larger, deeper, older (?) and plays more fundamental role in the Earth's tectonics. The wave planetology as hierarchically higher than geol- ogy (Earth is only one of planets and of many celestial bodies), states that all celestial bodies are dichotomic ( "Pacific" as a tectonic feature is found in any celestial body) and sectoral (i.g., the Arctic-Antarctic symptom is also in any body) (Theorems 1, 2 [1]). The tectonic dichotomy and sectoring are related to the first and second harmon- ica (wave1 and wave2) of warping standing waves appearing in any body just because they move in non-circular (elliptic, parabolic) orbits and hence inertia forces tend to distort original shapes. This disfiguring of a rotating body is not just a superficial fea- ture, it involves fundamental changes in the entire vertical section above and below surface rises and falls (Theorem 4 [1]). Here acts the law of angular momentum equi- libration. Thus, under the Pacific basin hollow -the deepest hollow produced by wave1 - mantle is denser than under the Atlantic and Indian oceanic basins - basins produced by wave2. We know it because squeezed out of mantle tholeiites in the mid-oceanic ridges are Fe-richer in Pacific than in other oceans. The "primary" ocean is thus a fundamental or "wave1" or 2pR-structure. The "secondary" oceans are "wave2" or pR-structures. pR-structures represented by continents, secondary oceans and basins and the "superswell" (Darwin rise) in the Pacific, i.e. by most important terrestrial lithospheric tectonic blocks, are distributed on the Earth's surface not randomly. As must be expected of the standing wave interference picture, the pR-structure pattern shows regular grouping around certain centres. There are 6 centres - vertices of an oc- tahedron occurring at equator (1, 2), tropics (3, 4) and polar circles (5, 6). They are: 1. New Guinea, 2. Equatorial Atlantic, 3. Easter Isl., 4. the Pamirs-Hindukush, 5. Bering Strait, 6. Bouvet Isl. There is expected antipodality between 1-2, 3-4, 5-6. The vertices of the structural octahedron combine around them sectors by a similar algorithm: there always converge two opposite differently uplifted sectors separated by two differently 1 subsided sectors. I.g., around the Pamirs-Hindukush there are two uplifted sectors: African (++) Asian (+), and two separating them subsided ones: Eurasian (-) Indo- ceanic (- -). The cosmically oriented structural octahedron and other regularities show that the wave induced structurization is a real predominant factor in planetology. Ref. [1] Kochemasov G.G.(1999) Geophys.Res.Abstr., v.1, 3, 700. 2

Global Modeling of Internal Tides Within an Eddying Ocean General Circulation Model

DTIC Science & Technology

2012-06-01

atmosphere and ocean (Yu and Weller, 2007 ). Salinities in the upper ocean are set by the difference between evaporation and precipitation at the ocean...surface (Yu, 2007 ; Schmitt, 2008). Because the buoyancy (density) of seawater at the ocean surface is con- trolled by temperature and salinity, the...days, these currents mean- der and generate highly energetic meso- scale eddies (Schmitz, 1996a,b; Stammer , 1997), the spinning oceanic dynamical

Asynchronous marine-terrestrial signals of the last deglacial warming in East Asia associated with low- and high-latitude climate changes.

PubMed

Xu, Deke; Lu, Houyuan; Wu, Naiqin; Liu, Zhenxia; Li, Tiegang; Shen, Caiming; Wang, Luo

2013-06-11

A high-resolution multiproxy record, including pollen, foraminifera, and alkenone paleothermometry, obtained from a single core (DG9603) from the Okinawa Trough, East China Sea (ECS), provided unambiguous evidence for asynchronous climate change between the land and ocean over the past 40 ka. On land, the deglacial stage was characterized by rapid warming, as reflected by paleovegetation, and it began ca. 15 kaBP, consistent with the timing of the last deglacial warming in Greenland. However, sea surface temperature estimates from foraminifera and alkenone paleothermometry increased around 20-19 kaBP, as in the Western Pacific Warm Pool (WPWP). Sea surface temperatures in the Okinawa Trough were influenced mainly by heat transport from the tropical western Pacific Ocean by the Kuroshio Current, but the epicontinental vegetation of the ECS was influenced by atmospheric circulation linked to the northern high-latitude climate. Asynchronous terrestrial and marine signals of the last deglacial warming in East Asia were thus clearly related to ocean currents and atmospheric circulation. We argue that (i) early warming seawater of the WPWP, driven by low-latitude insolation and trade winds, moved northward via the Kuroshio Current and triggered marine warming along the ECS around 20-19 kaBP similar to that in the WPWP, and (ii) an almost complete shutdown of the Atlantic Meridional Overturning Circulation ca. 18-15 kaBP was associated with cold Heinrich stadial-1 and delayed terrestrial warming during the last deglacial warming until ca. 15 kaBP at northern high latitudes, and hence in East Asia. Terrestrial deglacial warming therefore lagged behind marine changes by ca. 3-4 ka.

Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea ice

NASA Astrophysics Data System (ADS)

Humphries, R. S.; Klekociuk, A. R.; Schofield, R.; Keywood, M.; Ward, J.; Wilson, S. R.

2016-02-01

Better characterisation of aerosol processes in pristine, natural environments, such as Antarctica, have recently been shown to lead to the largest reduction in uncertainties in our understanding of radiative forcing. Our understanding of aerosols in the Antarctic region is currently based on measurements that are often limited to boundary layer air masses at spatially sparse coastal and continental research stations, with only a handful of studies in the vast sea-ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the icebreaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the polar front, with mean polar cell concentrations of 1130 cm-3 - higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low-pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air masses quickly from the free troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea-ice boundary layer air masses travelled equatorward into the low-albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei which, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between simulations and observations of cloud and aerosol over the Southern Ocean.

Asynchronous marine-terrestrial signals of the last deglacial warming in East Asia associated with low- and high-latitude climate changes

PubMed Central

Xu, Deke; Lu, Houyuan; Wu, Naiqin; Liu, Zhenxia; Li, Tiegang; Shen, Caiming; Wang, Luo

2013-01-01

A high-resolution multiproxy record, including pollen, foraminifera, and alkenone paleothermometry, obtained from a single core (DG9603) from the Okinawa Trough, East China Sea (ECS), provided unambiguous evidence for asynchronous climate change between the land and ocean over the past 40 ka. On land, the deglacial stage was characterized by rapid warming, as reflected by paleovegetation, and it began ca. 15 kaBP, consistent with the timing of the last deglacial warming in Greenland. However, sea surface temperature estimates from foraminifera and alkenone paleothermometry increased around 20–19 kaBP, as in the Western Pacific Warm Pool (WPWP). Sea surface temperatures in the Okinawa Trough were influenced mainly by heat transport from the tropical western Pacific Ocean by the Kuroshio Current, but the epicontinental vegetation of the ECS was influenced by atmospheric circulation linked to the northern high-latitude climate. Asynchronous terrestrial and marine signals of the last deglacial warming in East Asia were thus clearly related to ocean currents and atmospheric circulation. We argue that (i) early warming seawater of the WPWP, driven by low-latitude insolation and trade winds, moved northward via the Kuroshio Current and triggered marine warming along the ECS around 20–19 kaBP similar to that in the WPWP, and (ii) an almost complete shutdown of the Atlantic Meridional Overturning Circulation ca. 18–15 kaBP was associated with cold Heinrich stadial-1 and delayed terrestrial warming during the last deglacial warming until ca. 15 kaBP at northern high latitudes, and hence in East Asia. Terrestrial deglacial warming therefore lagged behind marine changes by ca. 3–4 ka. PMID:23720306

Numerical simulation of the world ocean circulation

NASA Technical Reports Server (NTRS)

Takano, K.; Mintz, Y.; Han, Y. J.

1973-01-01

A multi-level model, based on the primitive equations, is developed for simulating the temperature and velocity fields produced in the world ocean by differential heating and surface wind stress. The model ocean has constant depth, free slip at the lower boundary, and neglects momentum advection; so that there is no energy exchange between the barotropic and baroclinic components of the motion, although the former influences the latter through temperature advection. The ocean model was designed to be coupled to the UCLA atmospheric general circulation model, for the study of the dynamics of climate and climate changes. But here, the model is tested by prescribing the observed seasonally varying surface wind stress and the incident solar radiation, the surface air temperature and humidity, cloudiness and the surface wind speed, which, together with the predicted ocean surface temperature, determine the surface flux of radiant energy, sensible heat and latent heat.

Estimating Advective Near-surface Currents from Ocean Color Satellite Images

DTIC Science & Technology

2015-01-01

of surface current information. The present study uses the sequential ocean color products provided by the Geostationary Ocean Color Imager (GOCI) and...on the SuomiNational Polar-Orbiting Partner- ship (S-NPP) satellite. The GOCI is the world’s first geostationary orbit satellite sensor over the...used to extract the near-surface currents by the MCC algorithm. We not only demonstrate the retrieval of currents from the geostationary satellite ocean

1/f model for long-time memory of the ocean surface temperature

NASA Astrophysics Data System (ADS)

Fraedrich, Klaus; Luksch, Ute; Blender, Richard

2004-09-01

The 1/f spectrum of the ocean surface temperature in the Atlantic and Pacific midlatitudes is explained by a simple vertical diffusion model with a shallow mixed layer on top of a deep ocean. The model is forced at the air-sea interface with the total surface heat flux from a 1000 year climate simulation. The analysis reveals the role of ocean advection and substantiates estimates of internal thermal diffusivities.

Ocean surface partitioning strategies using ocean colour remote Sensing: A review

NASA Astrophysics Data System (ADS)

Krug, Lilian Anne; Platt, Trevor; Sathyendranath, Shubha; Barbosa, Ana B.

2017-06-01

The ocean surface is organized into regions with distinct properties reflecting the complexity of interactions between environmental forcing and biological responses. The delineation of these functional units, each with unique, homogeneous properties and underlying ecosystem structure and dynamics, can be defined as ocean surface partitioning. The main purposes and applications of ocean partitioning include the evaluation of particular marine environments; generation of more accurate satellite ocean colour products; assimilation of data into biogeochemical and climate models; and establishment of ecosystem-based management practices. This paper reviews the diverse approaches implemented for ocean surface partition into functional units, using ocean colour remote sensing (OCRS) data, including their purposes, criteria, methods and scales. OCRS offers a synoptic, high spatial-temporal resolution, multi-decadal coverage of bio-optical properties, relevant to the applications and value of ocean surface partitioning. In combination with other biotic and/or abiotic data, OCRS-derived data (e.g., chlorophyll-a, optical properties) provide a broad and varied source of information that can be analysed using different delineation methods derived from subjective, expert-based to unsupervised learning approaches (e.g., cluster, fuzzy and empirical orthogonal function analyses). Partition schemes are applied at global to mesoscale spatial coverage, with static (time-invariant) or dynamic (time-varying) representations. A case study, the highly heterogeneous area off SW Iberian Peninsula (NE Atlantic), illustrates how the selection of spatial coverage and temporal representation affects the discrimination of distinct environmental drivers of phytoplankton variability. Advances in operational oceanography and in the subject area of satellite ocean colour, including development of new sensors, algorithms and products, are among the potential benefits from extended use, scope and applications of ocean surface partitioning using OCRS.

Earth and space science - Oceans

NASA Technical Reports Server (NTRS)

Stewart, R. H.

1983-01-01

Satellite observations of the oceans are now being used to obtain new information about the oceanic geoid, currents, winds, tides and the interaction of the ocean with the atmosphere. In addition, satellites routinely relay information from the sea surface to laboratories on land, and determine the position of instruments drifting on the sea surface.

Seasonal dynamics of surface chlorophyll concentration and sea surface temperature, as indicator of hydrological structure of the ocean (by satellite data)

NASA Astrophysics Data System (ADS)

Shevyrnogov, Anatoly; Vysotskaya, Galina

Continuous monitoring of phytopigment concentrations and sea surface temperature in the ocean by space-borne methods makes possible to estimate ecological condition of biocenoses in critical areas. Unlike land vegetation, hydrological processes largely determine phytoplank-ton dynamics, which may be either recurrent or random. The types of chlorophyll concentration dynamics and sea surface temperature can manifest as zones quasistationary by seasonal dynamics, quasistationary areas (QSA). In the papers of the authors (A. Shevyrnogov, G. Vysotskaya, E. Shevyrnogov, A study of the stationary and the anomalous in the ocean surface chlorophyll distribution by satellite data. International Journal of Remote Sensing, Vol. 25, No.7-8, pp. 1383-1387, April 2004 & A. P. Shevyrnogov, G. S. Vysotskaya, J. I. Gitelson, Quasistationary areas of chlorophyll concentra-tion in the world ocean as observed satellite data Advances in Space Research, Volume 18, Issue 7, Pages 129-132, 1996) existence of zones, which are quasi-stationary with similar seasonal dynamics of chlorophyll concentration at surface layer of ocean, was shown. Results were obtained on the base of processing of time series of satellite images SeaWiFS. It was shown that fronts and frontal zones coincide with dividing lines between quasi-stationary are-as, especially in areas of large oceanic streams. To study the dynamics of the ocean for the period from 1985 through 2012 we used data on the temperature of the surface layer of the ocean and chlorophyll concentration (AVHRR, SeaWiFS and MODIS). Biota of surface oceanic layer is more stable in comparison with quickly changing surface tem-perature. It gives a possibility to circumvent influence of high-frequency component (for exam-ple, a diurnal cycle) in investigation of dynamics of spatial distribution of surface streams. In addition, an analyses of nonstable ocean productivity phenomena, stood out time series of satellite images, showed existence of areas with different types of instability in the all Global ocean. They are observed as adjacent nonstationary zones of different size, which are associ-ated by different ways with known oceanic phenomena. It is evident that dynamics of a spatial distribution of biological productivity can give an additional knowledge of complicated picture of surface oceanic layer hydrology. In this study we demonstrate different origin of appearance of quasistationary zones in the ocean. We can see that the border between quasi¬stationary zones is an indicator of the front between the Labrador Current and Gulfstream, other example of revealed pheno¬menon is a qua-sistationary area around of the British Isles that correlates with the relief of the oceanic bottom. Considering that the QSA maps are calculated almost for all surface of the Global ocean, not all QSA can be explained especially of small size. Although some small QSA are interesting. Also local QSA near estuaries of large rivers and large industrial centers, that can be result of a human impact. In sum satellite data is a powerful instrument for investigation of dynamic oceanic processes, their stability and unstability. The result of such study can be used for monitoring of long-term changes and their correlation of with climate dynamics.

Enhanced deep ocean ventilation and oxygenation with global warming

NASA Astrophysics Data System (ADS)

Froelicher, T. L.; Jaccard, S.; Dunne, J. P.; Paynter, D.; Gruber, N.

2014-12-01

Twenty-first century coupled climate model simulations, observations from the recent past, and theoretical arguments suggest a consistent trend towards warmer ocean temperatures and fresher polar surface oceans in response to increased radiative forcing resulting in increased upper ocean stratification and reduced ventilation and oxygenation of the deep ocean. Paleo-proxy records of the warming at the end of the last ice age, however, suggests a different outcome, namely a better ventilated and oxygenated deep ocean with global warming. Here we use a four thousand year global warming simulation from a comprehensive Earth System Model (GFDL ESM2M) to show that this conundrum is a consequence of different rates of warming and that the deep ocean is actually better ventilated and oxygenated in a future warmer equilibrated climate consistent with paleo-proxy records. The enhanced deep ocean ventilation in the Southern Ocean occurs in spite of increased positive surface buoyancy fluxes and a constancy of the Southern Hemisphere westerly winds - circumstances that would otherwise be expected to lead to a reduction in deep ocean ventilation. This ventilation recovery occurs through a global scale interaction of the Atlantic Meridional Overturning Circulation undergoing a multi-centennial recovery after an initial century of transient decrease and transports salinity-rich waters inform the subtropical surface ocean to the Southern Ocean interior on multi-century timescales. The subsequent upwelling of salinity-rich waters in the Southern Ocean strips away the freshwater cap that maintains vertical stability and increases open ocean convection and the formation of Antarctic Bottom Waters. As a result, the global ocean oxygen content and the nutrient supply from the deep ocean to the surface are higher in a warmer ocean. The implications for past and future changes in ocean heat and carbon storage will be discussed.

Salinity Processes in the Upper Ocean Regional Study (SPURS)

NASA Image and Video Library

2012-09-04

Ken Decoteau, left, and Chip Beniot, both of the Woods Hole Oceanographic Institution, move scientific instruments to the research vessel Knorr on Tuesday, Sept. 4, 2012, in Woods Hole, Mass. The instruments will be deployed in the Atlantic Ocean as part of the Salinity Processes in the Upper Ocean Regional Study (SPURS) which is set to sail on Sept. 6. The NASA-sponsored expedition will sail to the North Atlantic's saltiest spot to get a detailed, 3-D picture of how salt content fluctuates in the ocean's upper layers and how these variations are related to shifts in rainfall patterns around the planet. Photo Credit: (NASA/Bill Ingalls)

Salinity Processes in the Upper Ocean Regional Study (SPURS)

NASA Image and Video Library

2012-09-04

Chip Beniot, left, and Ken Decoteau, both of the Woods Hole Oceanographic Institution, move scientific instruments to the research vessel Knorr on Tuesday, Sept. 4, 2012, in Woods Hole, Mass. The instruments will be deployed in the Atlantic Ocean as part of the Salinity Processes in the Upper Ocean Regional Study (SPURS) which is set to sail on Sept. 6. The NASA-sponsored expedition will sail to the North Atlantic's saltiest spot to get a detailed, 3-D picture of how salt content fluctuates in the ocean's upper layers and how these variations are related to shifts in rainfall patterns around the planet. Photo Credit: (NASA/Bill Ingalls)

KSC-2009-1410

NASA Image and Video Library

2009-01-27

VANDENBERG AIR FORCE BASE, Calif. -- The first half of the fairing is moved into place around the NOAA-N Prime spacecraft in the launch service tower on Space Launch Complex 2 at Vandenberg Air Force Base in California. The fairing is a molded structure that fits flush with the outside surface of the rocket and forms an aerodynamically smooth nose cone, protecting the spacecraft during launch and ascent. NOAA-N Prime is the latest polar-orbiting operational environmental weather satellite developed by NASA for the National Oceanic and Atmospheric Administration. It is built by Lockheed Martin and similar to NOAA-N that was launched on May 20, 2005. Launch of NOAA-N Prime aboard a Delta II rocket is scheduled for Feb. 4. Photo credit: NASA

KSC-2009-1411

NASA Image and Video Library

2009-01-27

VANDENBERG AIR FORCE BASE, Calif. -- The first half of the fairing is moved into place around the NOAA-N Prime spacecraft in the launch service tower on Space Launch Complex 2 at Vandenberg Air Force Base in California. The fairing is a molded structure that fits flush with the outside surface of the rocket and forms an aerodynamically smooth nose cone, protecting the spacecraft during launch and ascent. NOAA-N Prime is the latest polar-orbiting operational environmental weather satellite developed by NASA for the National Oceanic and Atmospheric Administration. It is built by Lockheed Martin and similar to NOAA-N that was launched on May 20, 2005. Launch of NOAA-N Prime aboard a Delta II rocket is scheduled for Feb. 4. Photo credit: NASA

KSC-2009-1409

NASA Image and Video Library

2009-01-27

VANDENBERG AIR FORCE BASE, Calif. -- The first half of the fairing is moved into place around the NOAA-N Prime spacecraft in the launch service tower on Space Launch Complex 2 at Vandenberg Air Force Base in California. The fairing is a molded structure that fits flush with the outside surface of the rocket and forms an aerodynamically smooth nose cone, protecting the spacecraft during launch and ascent. NOAA-N Prime is the latest polar-orbiting operational environmental weather satellite developed by NASA for the National Oceanic and Atmospheric Administration. It is built by Lockheed Martin and similar to NOAA-N that was launched on May 20, 2005. Launch of NOAA-N Prime aboard a Delta II rocket is scheduled for Feb. 4. Photo credit: NASA

Air-sea interaction regimes in the sub-Antarctic Southern Ocean and Antarctic marginal ice zone revealed by icebreaker measurements

NASA Astrophysics Data System (ADS)

Yu, Lisan; Jin, Xiangze; Schulz, Eric W.; Josey, Simon A.

2017-08-01

This study analyzed shipboard air-sea measurements acquired by the icebreaker Aurora Australis during its off-winter operation in December 2010 to May 2012. Mean conditions over 7 months (October-April) were compiled from a total of 22 ship tracks. The icebreaker traversed the water between Hobart, Tasmania, and the Antarctic continent, providing valuable in situ insight into two dynamically important, yet poorly sampled, regimes: the sub-Antarctic Southern Ocean and the Antarctic marginal ice zone (MIZ) in the Indian Ocean sector. The transition from the open water to the ice-covered surface creates sharp changes in albedo, surface roughness, and air temperature, leading to consequential effects on air-sea variables and fluxes. Major effort was made to estimate the air-sea fluxes in the MIZ using the bulk flux algorithms that are tuned specifically for the sea-ice effects, while computing the fluxes over the sub-Antarctic section using the COARE3.0 algorithm. The study evidenced strong sea-ice modulations on winds, with the southerly airflow showing deceleration (convergence) in the MIZ and acceleration (divergence) when moving away from the MIZ. Marked seasonal variations in heat exchanges between the atmosphere and the ice margin were noted. The monotonic increase in turbulent latent and sensible heat fluxes after summer turned the MIZ quickly into a heat loss regime, while at the same time the sub-Antarctic surface water continued to receive heat from the atmosphere. The drastic increase in turbulent heat loss in the MIZ contrasted sharply to the nonsignificant and seasonally invariant turbulent heat loss over the sub-Antarctic open water.