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Sample records for sea level measurements

  1. Precise mean sea level measurements using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Kelecy, Thomas M.; Born, George H.; Parke, Michael E.; Rocken, Christian

    1994-01-01

    This paper describes the results of a sea level measurement test conducted off La Jolla, California, in November of 1991. The purpose of this test was to determine accurate sea level measurements using a Global Positioning System (GPS) equipped buoy. These measurements were intended to be used as the sea level component for calibration of the ERS 1 satellite altimeter. Measurements were collected on November 25 and 28 when the ERS 1 satellite overflew the calibration area. Two different types of buoys were used. A waverider design was used on November 25 and a spar design on November 28. This provided the opportunity to examine how dynamic effects of the measurement platform might affect the sea level accuracy. The two buoys were deployed at locations approximately 1.2 km apart and about 15 km west of a reference GPS receiver located on the rooftop of the Institute of Geophysics and Planetary Physics at the Scripps Institute of Oceanography. GPS solutions were computed for 45 minutes on each day and used to produce two sea level time series. An estimate of the mean sea level at both locations was computed by subtracting tide gage data collected at the Scripps Pier from the GPS-determined sea level measurements and then filtering out the high-frequency components due to waves and buoy dynamics. In both cases the GPS estimate differed from Rapp's mean altimetric surface by 0.06 m. Thus, the gradient in the GPS measurements matched the gradient in Rapp's surface. These results suggest that accurate sea level can be determined using GPS on widely differing platforms as long as care is taken to determine the height of the GPS antenna phase center above water level. Application areas include measurement of absolute sea level, of temporal variations in sea level, and of sea level gradients (dominantly the geoid). Specific applications would include ocean altimeter calibration, monitoring of sea level in remote regions, and regional experiments requiring spatial and temporal resolution higher than that available from altimeter data.

  2. Accurate measurement of mean sea level changes by altimetric satellites

    NASA Technical Reports Server (NTRS)

    Born, G. H.; Tapley, B. D.; Ries, J. C.; Stewart, R. H.

    1986-01-01

    A technique for monitoring changes in global mean sea levels using altimeter data from a well-tracked satellite is examined. The usefulness of this technique is evaluated by analyzing Seasat altimeter data obtained during July-September 1978. The effects of orbit errors, geoid errors, sampling intervals, tides, and atmosphere refraction on the calculation of the mean sea level are investigated. The data reveal that the stability of an altimeter can be determined with an accuracy of + or - 7 cm using globally averaged sea surface height measurements. The application of this procedure to the US/French Ocean Topography Experiment is discussed.

  3. Improving sea level record in arctic using ENVISAT altimeter measurements

    NASA Astrophysics Data System (ADS)

    Thibaut, Pierre; Poisson, Jean-Christophe; Hoang, Duc; Quartly, Graham; Kurekin, Andrey

    2015-04-01

    The Arctic is an important component of the climate system whose exact influence on ocean circulation is still poorly understood today. This region is also very sensitive to global warming and some direct consequences like melting ice are particularly visible. In this context, extending the knowledge of the sea level variability as far as possible in the Arctic Ocean is a valuable contribution to the understanding of rapid changes occurring in this region. Due to a particularly complex and unstable environment, ocean observation is challenging considering that sea level measurements can be widely corrupted by the presence of sea ice in the altimeter footprint. In the framework of the ESA Sea Level Climate Change Initiative project, new algorithms have been developed and implemented to process 10 years of ENVISAT altimeter data over the Arctic Ocean and to improve the sea level measurement in this region. The new processing chain contains three main steps. The first task consists in identifying altimetric returns for which a standard proven estimation processing may be used, and in flagging those requiring more sophisticated processing. This will include introducing a novel approach that uses the relationship with neighbouring waveforms to aid in the identification of key reflecting surfaces. The second task consists in applying estimators that performs better in situations where sea-ice covers partially or totally the observed surface. The last task consists in investigating the transition zones to make sure that no artificial discontinuities are introduced by the different processing and to reduce these discontinuities. We propose in this talk, to explain and illustrate the different steps of this study and to show important figures of improvement regarding the estimation of sea level variability in the Arctic Ocean.

  4. Sea level: measuring the bounding surfaces of the ocean.

    PubMed

    Tamisiea, Mark E; Hughes, Chris W; Williams, Simon D P; Bingley, Richard M

    2014-09-28

    The practical need to understand sea level along the coasts, such as for safe navigation given the spatially variable tides, has resulted in tide gauge observations having the distinction of being some of the longest instrumental ocean records. Archives of these records, along with geological constraints, have allowed us to identify the century-scale rise in global sea level. Additional data sources, particularly satellite altimetry missions, have helped us to better identify the rates and causes of sea-level rise and the mechanisms leading to spatial variability in the observed rates. Analysis of all of the data reveals the need for long-term and stable observation systems to assess accurately the regional changes as well as to improve our ability to estimate future changes in sea level. While information from many scientific disciplines is needed to understand sea-level change, this review focuses on contributions from geodesy and the role of the ocean's bounding surfaces: the sea surface and the Earth's crust. PMID:25157196

  5. Sea level: measuring the bounding surfaces of the ocean

    PubMed Central

    Tamisiea, Mark E.; Hughes, Chris W.; Williams, Simon D. P.; Bingley, Richard M.

    2014-01-01

    The practical need to understand sea level along the coasts, such as for safe navigation given the spatially variable tides, has resulted in tide gauge observations having the distinction of being some of the longest instrumental ocean records. Archives of these records, along with geological constraints, have allowed us to identify the century-scale rise in global sea level. Additional data sources, particularly satellite altimetry missions, have helped us to better identify the rates and causes of sea-level rise and the mechanisms leading to spatial variability in the observed rates. Analysis of all of the data reveals the need for long-term and stable observation systems to assess accurately the regional changes as well as to improve our ability to estimate future changes in sea level. While information from many scientific disciplines is needed to understand sea-level change, this review focuses on contributions from geodesy and the role of the ocean's bounding surfaces: the sea surface and the Earth's crust. PMID:25157196

  6. Measuring precise sea level from a buoy using the global positioning system

    SciTech Connect

    Rocken, C.; Kelecy, T.M.; Born, G.H. ); Young, L.E.; Purcell, G.H. Jr.; Wolf, S.K. )

    1990-11-01

    High-accuracy sea surface positioning is required for sea floor geodesy, satellite altimeter verification, and the study of sea level. An experiment to study the feasibility of using the Global Positioning System (GPS) for accurate sea surface positioning was conducted. A GPS-equipped buoy (floater) was deployed off the Scripps pier at La Jolla, California during December 13-15, 1989. Two reference GPS receivers were placed on land, one within {approximately}100 m of the floater, and the other about 80 km inland at the laser ranging site on Monument Peak. The position of the floater was determined relative to the land-fixed receivers using: (a) kinematic GPS processing software developed at the National Geodetic Survey (NGS), and (b) the Jet Propulsion Laboratory's GIPSY (GPS Inferred Positioning SYstem) software. Sea level and ocean wave spectra were calculated from GPPS measurements. These results were compared to measurements made with a NOAA tide gauge and a Paros{trademark} pressure transducer (PPT). GPS sea level for the short 100-m baseline agrees with the PPT sea level at the 1-cm level and has an rms variation of 5 mm over a period of 4 hours. Agreement between results with the two independent GPS analyses is on the order of a few millimeters. Processing of the longer Monument Peak - floater baseline is in progress and will require orbit adjustments and tropospheric modeling to obtain results comparable to the short baseline.

  7. Global sea level rise

    SciTech Connect

    Douglas, B.C. )

    1991-04-15

    Published values for the long-term, global mean sea level rise determined from tide gauge records exhibit considerable scatter, from about 1 mm to 3 mm/yr. This disparity is not attributable to instrument error; long-term trends computed at adjacent sites often agree to within a few tenths of a millimeter per year. Instead, the differing estimates of global sea level rise appear to be in large part due to authors' using data from gauges located at convergent tectonic plate boundaries, where changes of land elevation give fictitious sea level trends. In addition, virtually all gauges undergo subsidence or uplift due to postglacial rebound (PGR) from the last deglaciation at a rate comparable to or greater than the secular rise of sea level. Modeling PGR by the ICE-3G model of Tushingham and Peltier (1991) and avoiding tide gauge records in areas of converging tectonic plates produces a highly consistent set of long sea level records. The value for mean sea level rise obtained from a global set of 21 such stations in nine oceanic regions with an average record length of 76 years during the period 1880-1980 is 1.8 mm/yr {plus minus} 0.1. This result provides confidence that carefully selected long tide gauge records measure the same underlying trend of sea level and that many old tide gauge records are of very high quality.

  8. Measuring precise sea level from a buoy using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Rocken, Christian; Kelecy, Thomas M.; Born, George H.; Young, Larry E.; Purcell, George H., Jr.; Wolf, Susan Kornreich

    1990-01-01

    The feasibility of using the Global Positioning System (GPS) for accurate sea surface positioning was examined. An experiment was conducted on the Scripps pier at La Jolla, California from December 13-15, 1989. A GPS-equipped buoy was deployed about 100 m off the pier. Two fixed reference GPS receivers, located on the pier and about 80 km away on Monument Peak, were used to estimate the relative position of the floater. Kinematic GPS processing software, developed at the National Geodetic Survey, and the Jet Propulsion Laboratory's GPS Infrared Processing System software were used to determine the floater position relative to land-fixing receivers. Calculations were made of sea level and ocean wave spectra from GPS measurements. It is found that the GPS sea level for the short 100 m baseline agrees with the PPT sea level at the 1 cm level and has an rms variation of 5 mm over a period of 4 hours.

  9. Satellite Measurements of Sea Level Change: Where Have We Been and Where Are We Going

    NASA Astrophysics Data System (ADS)

    Nerem, R. S.; Chambers, D. P.; Leuliette, E. W.; Mitchum, G. T.; Cazenave, A.

    2006-07-01

    Our understanding of sea level change has improved consider ably over the last d ecade. Present- day knowledge of sea- level change is der ived from tide gauge observations and satellite altimetry measurements. The aver age rate of sea lev el change obtain ed from tide gauges ov er the last century is +1.8 mm/y ear. In comp arison, altimeter measurements have shown an aver age r ise of +3 .2 ± 0.4 mm/year sin ce 1992. The causes of the presen t-day rate are a combination of increases in ocean temp eratures and land ice melt from mountain glaciers, Greenland , and Antarctica. New satellite technologies, such as InSA R, GRACE and ICESat are mak ing signif icant contributions to understanding sea lev el change.

  10. Contemporary sea level rise.

    PubMed

    Cazenave, Anny; Llovel, William

    2010-01-01

    Measuring sea level change and understanding its causes has considerably improved in the recent years, essentially because new in situ and remote sensing observations have become available. Here we report on most recent results on contemporary sea level rise. We first present sea level observations from tide gauges over the twentieth century and from satellite altimetry since the early 1990s. We next discuss the most recent progress made in quantifying the processes causing sea level change on timescales ranging from years to decades, i.e., thermal expansion of the oceans, land ice mass loss, and land water-storage change. We show that for the 1993-2007 time span, the sum of climate-related contributions (2.85 +/- 0.35 mm year(-1)) is only slightly less than altimetry-based sea level rise (3.3 +/- 0.4 mm year(-1)): approximately 30% of the observed rate of rise is due to ocean thermal expansion and approximately 55% results from land ice melt. Recent acceleration in glacier melting and ice mass loss from the ice sheets increases the latter contribution up to 80% for the past five years. We also review the main causes of regional variability in sea level trends: The dominant contribution results from nonuniform changes in ocean thermal expansion. PMID:21141661

  11. Mediterranean sea level variations.

    NASA Astrophysics Data System (ADS)

    Vigo, I.; Sánchez Reales, J. M.; García, D.; Chao, B. F.

    2009-04-01

    In this work we report an updated study of the sea level variations for the Mediterranean sea for the period from October 1992 to January 2008. The study addresses two mayor issues: (i)The analysis of the spatial and temporal variability of sea surface height (SSH) from radar altimetry measurements (from TOPEX/Poseidon (T/P) + Jason-1, etc.). We use EOF analysis to explain most of its interannual variation, and how the different basins interact. (ii) The analysis of dynamics and balance of water mass transport for the whole period. We estimate the steric SSH by combining the steric SSH estimated from temperature and salt profiles simulated by the ECCO model with time-variable gravity (TVG) data (from GRACE) for the Mediterranean Sea. The estimated steric SSH together with the SSH obtained from altimetry allow for a more realistic estimation of the water mass variations in the Mediterranean for the whole period.

  12. Secular Change of the Geoid Geopotential Value, W0, from Sea Level Measurements and GRACE

    NASA Astrophysics Data System (ADS)

    Dayoub, Nadim; Moore, Philip; Penna, Nigel; Edwards, Stuart

    2010-05-01

    Current accuracy of satellite geodetic techniques enables investigation of the time variation of the fundamental geodetic parameter W0 as a response to sea level change and mass redistribution etc. In this study, we use two approaches to estimate the temporal variability of W0 : (i) a regional approach which utilizes tide gauge (TG) and co-located continuous GPS data to recover the annual geodetic coordinates of mean sea level at TG sites. By referencing these coordinates to a high resolution geopotential model such as EGM2008, the annual geopotential values are recovered, from which the secular trend of W0 is estimated. We use a minimum of 30 years of TG records and around 10 years of CGPS observations from nine sites in the UK and one in France. The CGPS time series enable estimation of the GIA and other geological signals at the TG sites and therefore an absolute sea level trend can be estimated. (ii) A global approach, in which radar altimetry provides a direct measure of the sea surface on a sub-monthly basis, for example, approximately every 10 days from TOPEX/Poseidon. Accordingly, a time series of global sea level measurements can be established. In addition, the GRACE mission is sensing the variation within the Earth's gravity field up to degree 60 in terms of spherical harmonics. Herein, data between 2002 and 2008 are used from JASON-1 and GRACE to recover monthly values of W0 which are used to infer the secular trend of the geoid geopotential. The influence of geocenter variation on W0 is also investigated. Keywords: Tide gauge, continuous GPS, JASON-1, GRACE

  13. Understanding Sea Level Changes

    NASA Technical Reports Server (NTRS)

    Chao, Benjamin F.

    2004-01-01

    Today more than 100 million people worldwide live on coastlines within one meter of mean sea level; any short-term or long-term sea level change relative to vertical ground motion is of great societal and economic concern. As palm-environment and historical data have clearly indicated the existence and prevalence of such changes in the past, new scientific information regarding to the nature and causes and a prediction capability are of utmost importance for the future. The 10-20 cm global sea-level rise recorded over the last century has been broadly attributed to two effects: (1) the steric effect (thermal expansion and salinity-density compensation of sea water) following global climate; (2) mass-budget changes due to a number of competing geophysical and hydrological processes in the Earth-atmosphere-hydrosphere-cryosphere system, including water exchange from polar ice sheets and mountain glaciers to the ocean, atmospheric water vapor and land hydrological variations, and anthropogenic effects such as water impoundment in artificial reservoirs and extraction of groundwater, all superimposed on the vertical motions of solid Earth due to tectonics, rebound of the mantle from past and present deglaciation, and other local ground motions. As remote-sensing tools, a number of space geodetic measurements of sea surface topography (e.g., TOPEX/Poseidon, Jason), ice mass (e.g., ICESat), time-variable gravity (e.g. GRACE), and ground motions (SLR, VLBI, GPS, InSAR, Laser altimetry, etc.) become directly relevant. Understanding sea level changes "anywhere, anytime" in a well-defined terrestrial reference frame in terms of climate change and interactions among ice masses, oceans, and the solid Earth, and being able to predict them, emerge as one of the scientific challenges in the Solid Earth Science Working Group (SESWG, 2003) conclusions.

  14. Sea level variation as an indicator of Florida current volume transport: comparisons with direct measurements.

    PubMed

    Maul, G A; Chew, F; Bushnell, M; Mayer, D A

    1985-01-18

    Sea level measurements from tide gauges at Miami, Florida, and Cat Cay, Bahamas, and bottom pressure measurements from a water depth of 50 meters off Jupiter, Florida, and a water depth of 10 meters off Memory Rock, Bahamas, were correlated with 81 concurrent direct volume transport observations in the Straits of Florida. Daily-averaged sea level from either gauge on the Bahamian side of the Straits was poorly correlated with transport. Bottom pressure off Jupiter had a linear coefficient of determination ofr(2) = 0.93, and Miami sea level, when adjusted for weather effects, had r(2) = 0.74; the standard errors of estimating transports were +/- 1.2 x 10(6) and +/- 1.9 x 10(6) cubic meters per second, respectively. A linear multivariate regression, which combined bottom pressure, weather, and the submarine cable observations between Jupiter and the Bahamas, had r(2) = 0.94 with a standard error of estimating transport of +/- 1.1 x 10(6) cubic meters per second. These results suggest that a combination of easily obtained observations is sufficient to adequatelv monitor the daily volume transport fluctuations of the Florida Current. PMID:17742102

  15. Late Pleistocene Sea Level Stack

    NASA Astrophysics Data System (ADS)

    Spratt, R. M.; Lisiecki, L. E.

    2014-12-01

    Sea level reconstructions have been created using wide variety of proxies and models. The accuracy of individual sea level reconstructions is limited by measurement, noise, local variations in salinity and temperature, and the assumptions particular to each reconstruction. To address these limitations, we have created a sea level stack (average) which increases the signal-to-noise ratio of sea level estimates by combining 5-7 sea level reconstructions over the last 800 kyr. Principal Component analysis (PCA) of seven sea level records from 0-430 kyr ago shows that 82% of the variance in these records is explained by their first principal component (i.e., the stack). Additionally, a stack of just the 5 longer records that extends to 800 kyr closely matches the timing and amplitude of our seven-record mean. We find that the mean sea level estimate for Marine Isotope Stage (MIS) 5e is 0-4 m above modern, and that the standard deviation of individual estimates is 11 m. Mean sea level estimates for MIS 11 are 12-16 m above modern with a standard deviation of 30 m. Due to the large variability between individual reconstructions, our sea level stack may provide more robust sea level estimates than any single technique.

  16. A novel method to measure sea-level with GLONASS-based GNSS-Reflectometry

    NASA Astrophysics Data System (ADS)

    Hobiger, Thomas; Haas, Rüdiger; Löfgren, Johan

    2014-05-01

    Global Navigation Satellite System (GNSS) applications usually process the received satellite signals to determine position, velocity or time of the receiver, or derive information about the atmosphere or ionosphere. In general, GNSS signals are transmitted from satellites and are expected to be received by a ground-based antenna, avoiding multi-path or reflections in order to achieve utmost high precision positioning results. Nevertheless, the information from reflected signals can become a valuable data source, from which (geo-) physical properties can be deduced. This approach, called GNSS-Reflectometry (GNSS-R), can be used to develop instruments that act as an altimeter when arrival times of direct and reflected signals are compared. Current GNSS-R systems usually entirely rely on signals from the Global Positioning Service (GPS). Field experiments could demonstrate that such systems can measure sea level with an accuracy of a few centimeter (Löfgren et al., 2011). However, the usage of the Russian GLONASS system, which has not been considered so far, has the potential to simplify the processing scheme and to allow handling of direct and reflected signals like a bi-static radar. Thus, such a GLONASS-based GNSS-R system was developed and deployed for test purposes at the Onsala Space Observatory, Sweden. Over a period of two weeks in October 2013, sea-level monitoring and measurements with the newly developed GLONASS-based GNSS-R system were carried out, in parallel to measurements with the conventional GPS-based GNSS-R installation at Onsala. In addition, data from tide gauge measurements were available for comparison. It can be shown that precision and accuracy of the GLONASS-based GNSS-R system is comparable to conventional GPS-based GNSS-R solutions. Moreover, the simplicity of the newly developed system allows to make it a cheap and valuable tool for a variety of ocean sciences applications. Such a system could be mounted on a vessel or aboard an airplane in order measure sea state parameters either close to the surface or from several kilometers above. When flown on a plane, so-called Delay-Doppler Maps (DDM) could be computed and this information could be used to determine, sea surface roughness, salinity, and to deduce wind parameters or other geophysical signals. References: J. S. Löfgren, R. Haas, H.-G. Scherneck, and M. S. Bos (2011), Three months of local sea level derived from reflected GNSS signals, Radio Science, 46(6), doi:10.1029/2011RS004693.

  17. 2D Backstripping Applied to Measuring Sea Level History at the New Jersey Margin (Invited)

    NASA Astrophysics Data System (ADS)

    Mountain, G. S.; Steckler, M. S.; Katz, M. E.; Browning, J. V.; Miller, K. G.

    2013-12-01

    IODP Expedition 313 cored and logged three sites in 33-35 m of water on the New Jersey inner shelf, targeting the rollover of buried clinothems where the imprint of past sea-level variation is especially well expressed and accessible to drilling. We report results of 2D backstripping along a seismic profile linking these sites and we show seafloor reconstructions that constrain the magnitudes of lower and mid-Miocene eustatic changes. 2D backstripping consists of five steps that sequentially remove the accumulated effects of subsidence and deformation, and reconstructs a seafloor transect at time intervals of one's choosing. We began by removing sediment above each of several dozen horizons previously mapped throughout a grid of high quality seismic data, allowing the underlying layers to unload using flexural isostasy with an elastic plate thickness of 23 to 30 km. We then made corrections for compaction due to the weight of overlying sediments removed in previous steps. These corrections were based on the exponential decrease in porosity with depth derived from log measurements within the boreholes, from MultiSensorCoreLogger measurements of unsplit cores, and from discrete samples extracted from each 1.5 m core section. Lateral changes in lithofacies/compaction between sites were estimated based on seismic facies and horizon geometry, and decompacted layers were restored to their original porosities and thicknesses. Corrections for thermal subsidence from the Oligocene to the present were made using a 2D thermal model for the New Jersey margin, based on knowledge of the sedimentary and lithospheric structure that provided estimates of the overall tectonic subsidence. Estimates for change in sea level since the time of each reconstruction were made by computing the paleobathymetry and adjusting the sea level height to optimally match the estimates of paleobathymetry, which were based on integrated litho- and biofacies of the relevant deposits at all three Exp. 313 sites. Varying sea level in this manner generated consistent paleodepth changes at a given time across the entire reconstruction, not just at a single location, lending support to the validity of the technique. We prepared reconstructions at the base, maximum flooding surface, and top of 18 mapped sequences spanning the interval 12.5 to 22 Ma to yield the true shapes of clinothems at their times of deposition. Not surprisingly, the present seaward tilt of nearly all surfaces and the relief of buried Miocene clinothems (some approach 400 m between topsets and toesets) are products of post-depositional processes; tilt and relief were much smaller when these surfaces were at the seafloor. However, actual paleo-water depths along each surface depend on past global sea-level elevation. Simultaneously fitting the constraints on all 3 wells required minor adjustments of interpretation. Due to uncertainties in flexural and compaction parameters, we are more confident of results for the amplitude of short-term (0.5-1.2 my) eustatic cycles than for the long-term rise and fall of sea level. We conclude that eustatic fluctuations from 13-16 Ma ranged from 6-50 m with an average 25 m amplitude; from 16-21 Ma fluctuations were typically larger, though few exceeded 60 m.

  18. Sea level variation

    NASA Technical Reports Server (NTRS)

    Douglas, Bruce C.

    1992-01-01

    Published values for the long-term, global mean sea level rise determined from tide gauge records range from about one to three mm per year. The scatter of the estimates appears to arise largely from the use of data from gauges located at convergent tectonic plate boundaries where changes of land elevation give fictitious sea level trends, and the effects of large interdecadal and longer sea level variations on short (less than 50+ years) or sappy records. In addition, virtually all gauges undergo subsidence or uplift due to isostatic rebound from the last deglaciation at a rate comparable to or greater than the secular rise of sea level. Modeling rebound by the ICE-3G model of Tushingham and Peltier (1990) and avoiding tide gauge records in areas of converging tectonic plates produces a highly consistent set of long sea level records. A global set of 21 such stations in nine oceanic regions with an average record length of 76 years during the period 1880-1980 yields the global sea level rise value 1.8 mm/year +/- 0.1. Greenhouse warming scenarios commonly forecast an additional acceleration of global sea level in the next 5 or 6+ decades in the range 0.1-0.2 mm/yr2. Because of the large power at low frequencies in the sea level spectrum, very long tide gauge records (75 years minimum) have been examined for past apparent sea level acceleration. For the 80-year period 1905-1985, 23 essentially complete tide gauge records in 10 geographic groups are available for analysis. These yielded the apparent global acceleration -0.011 (+/- 0.012) mm/yr2. A larger, less uniform set of 37 records in the same 10 groups with 92 years average length covering the 141 years from 1850-1991 gave 0.001 (+/- 0.008) mm/yr2. Thus there is no evidence for an apparent acceleration in the past 100+ years that is significant either statistically, or in comparison to values associated with global warming. Unfortunately, the large interdecadal fluctuations of sea level severely affect estimates of global sea level acceleration for time spans of less than about 50 years. This means that tide gauges alone cannot serve as a reliable leading indicator of climate change in less than many decades. This time required can be significantly reduced if the interdecadal fluctuations of sea level can be understood in terms of their forcing mechanisms, and then removed from the tide gauge records.

  19. Sea level change

    SciTech Connect

    Meier, M.F.

    1996-12-31

    The IPCC (Intergovernmental Panel on Climate Change) 1995 Scientific Assessment, Chapter 7. Sea Level Change, presents a modest revision of the similar chapter in the 1990 Assessment. Principal conclusions on observed sea-level change and the principal terms in the sea-level equation (ocean thermal expansion, glaciers, ice sheets, and land hydrology), including our knowledge of the present-day (defined as the 20th Century) components of sea-level rise, and projections of these for the future, are presented here. Some of the interesting glaciological problems which are involved in these studies are discussed in more detail. The emphasis here is on trends over decades to a century, not on shorter variations nor on those of the geologic past. Unfortunately, some of the IPCC projections had not been agreed at the time of writing of this paper, and these projections will not be given here. 15 refs., 2 figs.

  20. High-Level Clouds and Relation to Sea Surface Temperature as Inferred from Japan's GMS Measurements

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah; Lindzen, Richard S.; Lee, Kyu-Tae; Einaudi, Franco (Technical Monitor)

    2000-01-01

    High-level clouds have a significant impact on the radiation energy budgets and, hence, the climate of the Earth. Convective cloud systems, which are controlled by large-scale thermal and dynamical conditions, propagate rapidly within days. At this time scale, changes of sea surface temperature (SST) are small. Radiances measured by Japan's Geostationary Meteorological Satellite (GMS) are used to study the relation between high-level clouds and SST in the tropical western and central Pacific (30 S-30 N; 130 E-170 W), where the ocean is warm and deep convection is intensive. Twenty months (January 1998 - August, 1999) of GMS data are used, which cover the second half of the strong 1997-1998 El Nino. Brightness temperature at the 11-micron channel is used to identify high-level clouds. The core of convection is identified based on the difference in the brightness temperatures of the 11- and 12-micron channels. Because of the rapid movement of clouds, there is little correlation between clouds six hours apart. When most of deep convection moves to regions of high SST, the domain averaged high-level cloud amount decreases. A +2C change of SST in cloudy regions results in a relative change of -30% in high-level cloud amount. This large change in cloud amount is due to clouds moving from cool regions to warm regions but not the change in SST itself. A reduction in high-level cloud amount in the equatorial region implies an expanded dry upper troposphere in the off-equatorial region, and the greenhouse warming of high clouds and water vapor is reduced through enhanced longwave cooling to space. The results are important for understanding the physical processes relating SST, convection, and water vapor in the tropics. They are also important for validating climate simulations using global general circulation models.

  1. Caribbean Sea Level Network

    NASA Astrophysics Data System (ADS)

    von Hillebrandt-Andrade, C.; Crespo Jones, H.

    2012-12-01

    Over the past 500 years almost 100 tsunamis have been observed in the Caribbean and Western Atlantic, with at least 3510 people having lost their lives to this hazard since 1842. Furthermore, with the dramatic increase in population and infrastructure along the Caribbean coasts, today, millions of coastal residents, workers and visitors are vulnerable to tsunamis. The UNESCO IOC Intergovernmental Coordination Group for Tsunamis and other Coastal Hazards for the Caribbean and Adjacent Regions (CARIBE EWS) was established in 2005 to coordinate and advance the regional tsunami warning system. The CARIBE EWS focuses on four areas/working groups: (1) Monitoring and Warning, (2) Hazard and Risk Assessment, (3) Communication and (4) Education, Preparedness and Readiness. The sea level monitoring component is under Working Group 1. Although in the current system, it's the seismic data and information that generate the initial tsunami bulletins, it is the data from deep ocean buoys (DARTS) and the coastal sea level gauges that are critical for the actual detection and forecasting of tsunamis impact. Despite multiple efforts and investments in the installation of sea level stations in the region, in 2004 there were only a handful of sea level stations operational in the region (Puerto Rico, US Virgin Islands, Bermuda, Bahamas). Over the past 5 years there has been a steady increase in the number of stations operating in the Caribbean region. As of mid 2012 there were 7 DARTS and 37 coastal gauges with additional ones being installed or funded. In order to reach the goal of 100 operational coastal sea level stations in the Caribbean, the CARIBE EWS recognizes also the importance of maintaining the current stations. For this, a trained workforce in the region for the installation, operation and data analysis and quality control is considered to be critical. Since 2008, three training courses have been offered to the sea level station operators and data analysts. Other requirements and factors have been considered for the sustainability of the stations. The sea level stations have to potentially sustain very aggressive conditions of not only tsunamis, but on a more regular basis, hurricanes. Given the requirement that the data be available in near real time, for tsunami and other coastal hazard application, robust communication systems are also essential. For the local operator, the ability to be able to visualize the data is critical and tools like the IOC Sea level Monitoring Facility and the Tide Tool program are very useful. It has also been emphasized the need for these stations to serve multiple purposes. For climate and other research applications the data need to be archived, QC'd and analyzed. Increasing the user base for the sea level data has also been seen as an important goal to gain the local buy in; local weather and meteorological offices are considered as key stakeholders but for whom applications still need to be developed. The CARIBE EWS continues to look forward to working with other IOC partners including the Global Sea Level Observing System (GLOSS) and Sub-Commission for the Caribbean and Adjacent Regions (IOCARIBE)/GOOS, as well as with local, national and global sea level station operators and agencies for the development of a sustainable sea level network.

  2. Sea Level Rise in Tuvalu

    NASA Astrophysics Data System (ADS)

    Lin, C. C.; Ho, C. R.; Cheng, Y. H.

    2012-04-01

    Most people, especially for Pacific Islanders, are aware of the sea level change which may caused by many factors, but no of them has deeper sensation of flooding than Tuvaluan. Tuvalu, a coral country, consists of nine low-lying islands in the central Pacific between the latitudes of 5 and 10 degrees south, has the average elevation of 2 meters (South Pacific Sea Level and Climate Monitoring Project, SPSLCMP report, 2006) up to sea level. Meanwhile, the maximum sea level recorded was 3.44m on February 28th 2006 that damaged Tuvaluan's property badly. Local people called the flooding water oozes up out of the ground "King Tide", that happened almost once or twice a year, which destroyed the plant, polluted their fresh water, and forced them to colonize to some other countries. The predictable but uncontrollable king tide had been observed for a long time by SPSLCMP, but some of the uncertainties which intensify the sea level rise need to be analyzed furthermore. In this study, a span of 18 years of tide gauge data accessed from Sea Level Fine Resolution Acoustic Measuring Equipment (SEAFRAME) are compared with the satellite altimeter data accessed from Archiving Validation and Interpretation of Satellite Data in Oceanography (AVISO). All above are processed under the limitation of same time and spatial range. The outcome revealed a 9.26cm difference between both. After the tide gauge data shifted to the same base as altimeter data, the results showed the unknown residuals are always positive under the circumstances of the sea level rise above 3.2m. Apart from uncertainties in observing, the residual reflected unknown contributions. Among the total case number of sea level rise above 3.2m is 23 times, 22 of which were recorded with oceanic warm eddy happened simultaneously. The unknown residual seems precisely matched with oceanic warm eddies and illustrates a clear future approach for Tuvaluan to care for.

  3. The actual measurements at the tide gauges do not support strongly accelerating twentieth-century sea-level rise reconstructions

    NASA Astrophysics Data System (ADS)

    Parker, A.

    2016-03-01

    Contrary to what is claimed by reconstructions of the Global Mean Sea Level (GMSL) indicating accelerating sea level rates of rise over the twentieth-century, the actual measurements at the tide gauges show the sea levels have not risen nor accelerated that much. The most recent estimation by Hay et al [1] of the twentieth-century global mean sea level (GMSL) rise is the last attempt to give exact reconstructions without having enough information of the state of the world oceans over a century where unfortunately the good measurements were not that many. The information on relative rates of rise at the tide gauges and land subsidence of global positioning system (GPS) domes suggest the relative rate of rise is about 0.25mm/year, without any detectable acceleration. [The naïve average of all the world tide gauges of sufficient quality and length of the Permanent Service to Mean Sea Level (PSMSL) data base], Both the relative rates of rise at the tide gauges and the land vertical velocity of GPS domes of the Système d'Observation du Niveau des Eaux Littorales (SONEL) data base are strongly variable in space and time to make a nonsense the GMSL estimation.

  4. Baseline Measurements of Trace Gases at High Mountain and Sea-level Stations in Taiwan

    NASA Astrophysics Data System (ADS)

    Ou-Yang, C.; Wang, J.; Lin, N.; Lee, C.; Sheu, G.; Hsieh, H.; Liu, W.

    2012-12-01

    High mountains in Taiwan may serve as ideal locations to monitor seasonal alternation of air masses from Asian continental outflow from mainland China, biomass burning from Southeast Asia, and oceanic influences from the Pacific. The operation of Lulin Atmospheric Background Station (LABS, 23.51°N, 120.92°E, 2862 m a.s.l.) started in April 2006, aiming at studying the regional baseline conditions and its coupling with local air quality. Based on six-year's measurements, the springtime maximum of CO and O3 is likely caused by the long-range transport of air masses from Southeast Asia with biomass burning signature. In contrast, the Pacific oceanic air masses cause the summertime minimum. Diurnal variations of CO and O3 at LABS were found to be different from those at the surface. CO show maximum levels in late afternoon, and minima at night. O3 however shows a nearly opposite cycle to CO with minima at noon. Intriguingly, this O3 diurnal pattern repeated for five years, but changed since May 2011 for reasons that remain to be unraveled. Ozone depleting substance such as CFCs and Halons, and GHGs such as CO2 and CH4 were observed continuously at LABS since December 2007 and March 2011, respectively. Years after the implementation of the Montreal Protocols for the A5 countries, the ODS are expected to decline over time. Based on the measurements of seven halocarbons at LABS, most of the species are found to be either leveling off or decreasing during this period. For CO2 and CH4 measurements, a cavity ring-down spectroscopy was used and their seasonal variations were found to be similar to those at other sites in the East Asia. The results of flask samples analyzed by NOAA/ESRL/GMD were also discussed in this study. In addition to LABS, baseline observation was also conducted on a small island - Dongsha (20.70°N, 116.73°E), which is situated between Taiwan and the Philippines, serving as an ideal representative of the northern South China Sea. Both GHGs and O3 were measured during the spring of 2010. Our measurements and simulations suggested that strong northeasterly winds arising from the spring Asian monsoon may have transported polluted air masses from the northern continent to locations as south as Dongsha. Asian continental outflow is likely to be the cause for the seasonality of GHGs measured at Dongsha Island.

  5. The genesis of sea level variability in the Barents Sea

    NASA Astrophysics Data System (ADS)

    Volkov, Denis L.; Landerer, Felix W.; Kirillov, Sergey A.

    2013-09-01

    The regional variability of sea level is an integral indicator of changing oceanographic conditions due to different processes of oceanic, atmospheric, and terrestrial origin. The present study explores the nature of sea level variability in the Barents Sea-a marginal shelf sea of the Arctic Ocean. A characteristic feature that distinguishes this sea from other Arctic shelf seas is that it is largely ice free throughout the year. This allows continuous monitoring of sea level by space-borne altimeters. In this work we combine satellite altimetry, ocean gravity measurements by GRACE satellites, available hydrography data, and a high-resolution ocean data synthesis product to estimate the steric and mass-related components of sea level in the Barents Sea. We present one of the first observational evidence of the local importance of the mass-related sea level changes. The observed 1-3 month phase lag between the annual cycles of sea level in the Barents Sea and in the Nordic seas (Norwegian, Iceland, Greenland seas) is explained by the annual mass-related changes. The analysis of the barotropic vorticity budget shows that the mass-related sea level variability in the central part of the Barents Sea is determined by the combined effect of wind stress, flow over the varying bottom topography, and dissipation, while the impact of vorticity fluxes is negligible. Overall, the steric sea level has smaller amplitudes and mainly varies on the seasonal time scale. The thermosteric sea level is the main contributor to the steric sea level along the pathways of the Atlantic inflow into the Barents Sea. The relative contribution of the halosteric sea level is dominant in the southeastern, eastern, and northern parts of the Barents Sea, modulated by the seasonal sea ice formation/melt as well as by continental runoff. The variability of the thermosteric sea level in the Barents Sea is mostly driven by variations in the net surface heat flux, whereas the contribution of heat advection becomes as important as the ocean-atmosphere heat exchange at interannual time scales.

  6. Sea level anomalies exacerbate beach erosion

    NASA Astrophysics Data System (ADS)

    Theuerkauf, Ethan J.; Rodriguez, Antonio B.; Fegley, Stephen R.; Luettich, Richard A.

    2014-07-01

    Sea level anomalies are intra-seasonal increases in water level forced by meteorological and oceanographic processes unrelated to storms. The effects of sea level anomalies on beach morphology are unknown but important to constrain because these events have been recognized over large stretches of continental margins. Here, we present beach erosion measurements along Onslow Beach, a barrier island on the U.S. East Coast, in response to a year with frequent sea level anomalies and no major storms. The anomalies enabled extensive erosion, which was similar and in most places greater than the erosion that occurred during a year with a hurricane. These results highlight the importance of sea level anomalies in facilitating coastal erosion and advocate for their inclusion in beach-erosion models and management plans. Sea level anomalies amplify the erosive effects of accelerated sea level rise and changes in storminess associated with global climate change.

  7. Measuring the level of agreement in hematologic and biochemical values between blood sampling sites in leatherback sea turtles (Dermochelys coriacea).

    PubMed

    Stewart, Kimberly; Mitchell, Mark A; Norton, Terry; Krecek, Rosina C

    2012-12-01

    Conservation programs to protect endangered sea turtles are being instituted worldwide. A common practice in these programs is to collect blood to evaluate the health of the turtles. Several different venipuncture sites are used to collect blood from sea turtles for hematologic and biochemistry tests, depending on the species. To date, it is unknown what affect venipuncture site may have on sample results. The purpose of this study was to measure the level of agreement between hematologic and biochemistry values collected from the dorsal cervical sinus and the interdigital vein of leatherback (Dermochelys coriacea) sea turtles. Paired heparinized blood samples were obtained from the dorsal cervical sinus and the interdigital vein of 12 adult female nesting leatherback sea turtles on Keys Beach, St. Kitts, West Indies. Even though the sample population was small, the data for each chemistry were normally distributed, except for creatine kinase (CK). There was no significant difference when comparing biochemistry or hematologic values by venipuncture site, except for CK (P = 0.02). The level of agreement between sampling sites was considered good for albumin, calcium, globulin, glucose, packed cell volume, phosphorus, potassium, sodium, total protein, total solids, uric acid, white blood cell count, and all of the individual white cell types, while the level of agreement for aspartate aminotransferase and CK were considered poor. This information, coupled with the fact that the interdigital vein affords a less-invasive procedure, demonstrates that the interdigital vein is an appropriate location to use when establishing a hematologic and biochemical profile for leatherback sea turtles. PMID:23272336

  8. Seasonal sea level variations in the gulf of Cadiz continental shelf from in-situ measurements and satellite altimetry

    NASA Astrophysics Data System (ADS)

    Laiz, I.; Gmez-Enri, J.; Tejedor, B.; Aboitiz, A.; Villares, P.

    2013-02-01

    Long-term time series (1997-2008) of gridded multi-mission near shore altimeter data and in-situ tide gauge records have been analyzed to investigate the seasonal variability of sea level along the Gulf of Cadiz continental shelf and the Strait of Gibraltar. The contribution of different forcing mechanisms including atmospheric pressure, wind, steric anomalies and river runoff was also addressed. Comparison between altimeter and ground-truth data showed that the former can be a valuable tool to study the sea level seasonal cycle near the coast as well as to detect anomalous data from neighboring tide gauges. Overall, both sets of time series presented a similar mean seasonal cycle along the coast, dominated by the annual component and, to a lesser extent, by the semiannual one. Low-frequency atmospheric pressure and steric anomalies were the main forcing factors affecting the sea level seasonal cycle, their effect diminishing toward the Strait of Gibraltar. The combined effect of both forcing factors accounted for 55-61%/62-63% of the observed sea level variance at the tide gauge stations/ altimeter points located outside the Strait of Gibraltar and for only 27%/48% at those placed within the Strait. The influence of local wind was small in all stations except for the westernmost tide gauges. The effect of large river discharges was notable at the tide gauge located within the Guadalquivir river mouth, with 18% of the pressure-adjusted sea level variance explained, and negligible (< 0.1%) at the one placed within the Tinto-Odiel rivers mouth, indicating that such effects only need to be taken into account when dealing with tide gauges located within major river estuaries. Moreover, the effect of river runoff seems to be confined within a small area near the river mouth, thus not affecting the altimeter measurements. A small but significant influence of the wintertime North Atlantic Oscillation on sea level was observed, its effect being mainly reflected through changes in the atmospheric pressure, wind and river discharge.

  9. Sonmicat: Sea Level Observation System of Catalonia

    NASA Astrophysics Data System (ADS)

    Martinez-Benjamin, J. J.; Termens, A.; Ruiz, A.; Gonzalez Lopez, S.

    2014-12-01

    SONMICAT is the integrated sea level observation system of Catalonia. SONMICAT aims at providing high-quality continous measurements of sea- and land levels at the Catalan coast from tide gauges (relative sea levels) and from modern geodetic techniques (vertical land motion and absolute sea levels) for studies on long-term sea level trends, but also the calibration of satellite altimeters, for instance. This synergy is indeed the only way to get a clear and unambigous picture of what is actually going on at the coast of Catalonia. SONMICAT aims to be: - an integrated sea level monitoring system (different types of data, sources, time and space scales), - a sea level information system handling the data measured by different observation networks, - a local/regional component of international sea level observing systems (GLOSS, ESEAS, etc.), and - a local/regional interface for related European and Global projects and databases (PSML, TIGA, etc.) There is a gap of sea level data (GLOSS, PSML, TIGA) in the coast of Catalonia, although several groups and institutions have started to do some work. SONMICAT will fill it. Up to now, the system has started at l'Estartit and Barcelona harbours. A description of the actual SONMICAT infraestructure and campaigns - especially at Barcelona harbour - are presented. In June 2014, an airborne LiDAR campaign has been carrying on in Barcelona following two ICESat tracks. First results of the airborne survey will also be presented.

  10. Two Sea-Level Challenges

    NASA Astrophysics Data System (ADS)

    Galvin, C.

    2008-12-01

    "No place on the sandy ocean shores of the world has been shown to be eroding because of sea level rise." This statement appeared nearly 19 years ago in bold print at the top of the page in a brief article published in Shore and Beach (Galvin,1990). The term "sea level rise" was defined in 1990 as follows: "In this statement, "sea level rise" has the meaning that the average person on the street usually attaches to that term. That is, sea level is rising; not, as in some places like the Mississippi River delta, land level is sinking." While still a subject of controversy, it is now (2008) increasingly plausible (Tornqvist et al,2008) that damage from Hurricane Katrina was significantly worse on the Mississippi River delta because floodwaters exploited wetlands and levees whose elevations had been lowered by decades of compaction in the underlying soil. (1) "Sea level" commonly appears in the literature as "relative sea level rise", occurring that way in 711 publications between 1980 and 2009 (GeoRef database on 8 Sep 08). "Relative sea level rise" does not appear in the 2005 AGI Glossary. The nearest Glossary term is "relative change in sea level", but that term occurs in only 12 publications between 1980 and 2009. The Glossary defines this term in a sequence stratigraphy sense, which infers that "relative sea level rise" is the sum of bottom subsidence and eustatic sea level rise. In plain English, "relative sea level rise" means "water depth increase". For present day coastal environments, "relative sea level rise" is commonly used where eustatic sea level rise is less than subsidence, that is, where the magnitude of actual sea level rise is smaller than the magnitude of subsidence. In that situation, "relative sea level rise" misleads both the average person and the scientist who is not a coastal geologist. Thus, the first challenge is to abandon "relative sea level rise" in favor of "water depth increase", in order that the words accurately descibe what happens. It would further clarify popular understanding if the term "actual sea level rise" were used in place of "eustatic sea level rise". (2)Geologists have approximated the the practice of paleontologists and biologists in establishing type examples of important geological features. This is a useful practice. A graduate geologist holds in mind clear conceptions of "beach cusps", "drumlin fields", "birdfoot deltas", and "igneous sills" based on seeing field examples accepted by professional geologists as representative of these features. However, although publications frequently report that sea level rise erodes a particular beach, no one identifies a type beach where that cause has been proven to produce the alleged effect. At the type beach, it is necessary to show that sea level is rising, and that the beach erodes primarily from this sea level rise, rather than from interrupted longshore transport. Thus, the second challenge is to identify a type ocean beach proven to erode because of sea level rise.

  11. Uncertainties in measuring populations potentially impacted by sea level rise and coastal flooding.

    PubMed

    Mondal, Pinki; Tatem, Andrew J

    2012-01-01

    A better understanding of the impact of global climate change requires information on the locations and characteristics of populations affected. For instance, with global sea level predicted to rise and coastal flooding set to become more frequent and intense, high-resolution spatial population datasets are increasingly being used to estimate the size of vulnerable coastal populations. Many previous studies have undertaken this by quantifying the size of populations residing in low elevation coastal zones using one of two global spatial population datasets available - LandScan and the Global Rural Urban Mapping Project (GRUMP). This has been undertaken without consideration of the effects of this choice, which are a function of the quality of input datasets and differences in methods used to construct each spatial population dataset. Here we calculate estimated low elevation coastal zone resident population sizes from LandScan and GRUMP using previously adopted approaches, and quantify the absolute and relative differences achieved through switching datasets. Our findings suggest that the choice of one particular dataset over another can translate to a difference of more than 7.5 million vulnerable people for countries with extensive coastal populations, such as Indonesia and Japan. Our findings also show variations in estimates of proportions of national populations at risk range from <0.1% to 45% differences when switching between datasets, with large differences predominantly for countries where coarse and outdated input data were used in the construction of the spatial population datasets. The results highlight the need for the construction of spatial population datasets built on accurate, contemporary and detailed census data for use in climate change impact studies and the importance of acknowledging uncertainties inherent in existing spatial population datasets when estimating the demographic impacts of climate change. PMID:23110208

  12. Probability of sea level rise

    SciTech Connect

    Titus, J.G.; Narayanan, V.K.

    1995-10-01

    The report develops probability-based projections that can be added to local tide-gage trends to estimate future sea level at particular locations. It uses the same models employed by previous assessments of sea level rise. The key coefficients in those models are based on subjective probability distributions supplied by a cross-section of climatologists, oceanographers, and glaciologists.

  13. Comparison of sea-level measurements between microwave radar and subsurface pressure gauge deployed at select locations along the coast of India

    NASA Astrophysics Data System (ADS)

    Mehra, Prakash; Prabhudesai, Ramachandra Gopal; Joseph, Antony; Kumar, Vijay; Agarvadekar, Yogesh; Luis, Ryan; Nadaf, Lalsab

    2013-01-01

    Sea-level data are obtained from several remote and coastal locations using absolute pressure gauges deployed at known level, known as chart datum. However, to yield correct sea-level measurements from absolute pressure measurements, it is necessary to take into account the atmospheric pressure and water density at the measurement locations. We used data collected from microwave radar and an absolute pressure gauge deployed at Verem, Goa (January 2009 to May 2010), Tuticorin, and Mandapam, Tamil Nadu (June 2010 to March 2011) to carry out comparative studies. The root-mean-square difference between the estimated sea level from radar and pressure gauge (incorporating atmospheric pressure correction) is ˜2.69, 2.73, and 1.46 cm at Verem, Tuticorin, and Mandapam, respectively. Harmonic analysis of the two time-series of sea-level data at Verem produces similar residuals and tidal constituents. Our results indicate the importance of concurrent measurement of atmospheric pressure along with subsurface absolute pressure gauge measurements. Internet-based real-/near-real-time tracking and monitoring of sea level, sea state, and surface-meteorological conditions from a network of several island and coastal stations provides considerable information to disaster managers and local administrators during episodic events such as storms, storm surges, and tsunamis.

  14. Measurement of stress effects (scope for growth) and contaminant levels in mussels (Mytilus edulis) collected from the Irish Sea.

    PubMed

    Widdows, J; Donkin, P; Staff, F J; Matthiessen, P; Law, R J; Allen, Y T; Thain, J E; Allchin, C R; Jones, B R

    2002-05-01

    The objective of this research was to quantify the impact of pollution along the coastlines of the Irish Sea. Pollution assessment was based on the combined measurement of scope for growth (SFG), and chemical contaminants in the tissues of mussels (Mytilus edulis) collected from 38 coastal sites around the Irish Sea during June-July in 1996 and 1997. On the UK mainland coast, the SFG showed a general trend with a significant decline in water quality in the Liverpool and Morecambe Bay region. High water quality was recorded along the west coast of Wales, as well as southwest England and northwest Scotland (clean reference sites outside the Irish Sea). Along the coast of Ireland there was a similar trend with reduced SFG within the Irish Sea region. SFG was generally low north of Duncannon and then improved north of Belfast. The poor water quality on both sides of the Irish Sea is consistent with the prevailing hydrodynamics and the spatial distribution of contaminants associated with urban/ industrial development. The decline in SFG of mussels on both sides of the Irish Sea was associated with a general increase in contaminant levels in the mussels. Certain contaminants, including PAHs, TBT, sigmaDDT, Dieldrin, gamma-HCH, PCBs, and a few of the metals (Cd, Se, Ag, Pb), showed elevated concentrations. Many of these contaminants were particularly elevated in the coastal margins of Liverpool Bay, Morecambe Bay and Dublin Bay. A quantitative toxicological interpretation (QTI) of the combined tissue residue chemistry and SFG measurements indicated that at the majority of coastal sites, c. 50 to > 80% of the observed decline in SFG was due to PAHs as a result of fossil fuel combustion and oil spills. TBT levels were highest at major ports and harbours, but these concentrations only made a minor contribution to the overall reduction in SFG. At no sites were individual metals accumulated to concentrations that could cause a significant effect on SFG. The study identified many sites where the observed reduction in SFG was far greater than predicted from the limited number of chemical contaminants analysed, thus indicating the presence of additional 'unknown toxicants'. Sewage (containing domestic, agricultural and industrial components) appears to be an important contributor to reduced SFG and linear alkylbenzenes (LABs) and As may provide suitable 'sewage markers'. There was a highly significant positive correlation between SFG and As (P < 0.001). This relationship may be due to reduced As uptake by algal food material and mussels at sites with elevated P04 concentrations (e.g. at sites with sewage inputs). Phosphate is a known competitive inhibitor of As accumulation, at least in algae. The results highlight that further research is required on 'sewage markers' in mussels. The SFG approach therefore provides a rapid, cost-effective and quantitative measure of pollution impact, as well as a means of identifying the causes through a QTI of tissue contaminants levels. It also serves to identify the presence of unidentified toxicants and areas that require further study. PMID:11991207

  15. Measurement of integrated flux of cosmic ray muons at sea level using the INO-ICAL prototype detector

    SciTech Connect

    Pal, S.; Acharya, B.S.; Majumder, G.; Mondal, N.K.; Samuel, D.; Satyanarayana, B. E-mail: acharya@tifr.res.in E-mail: nkm@tifr.res.in E-mail: bsn@tifr.res.in

    2012-07-01

    The India-based Neutrino Observatory (INO) collaboration is planning to set-up a magnetized Iron-CALorimeter (ICAL) to study atmospheric neutrino oscillations with precise measurements of oscillations parameters. The ICAL uses 50 kton iron as target mass and about 28800 Resistive Plate Chambers (RPC) of 2 m × 2 m in area as active detector elements. As part of its R and D program, a prototype detector stack comprising 12 layers of RPCs of 1 m × 1 m in area has been set-up at Tata Institute of Fundamental Research (TIFR) to study the detector parameters using cosmic ray muons. We present here a study of muon flux measurement at sea level and lower latitude. (Site latitude: 18°54'N, longitude: 72°48'E.)

  16. Assimilation of TOPEX Sea Level Measurements with a Reduced-Gravity, Shallow Water Model of the Tropical Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Fukumori, Ichiro

    1995-01-01

    Sea surface height variability measured by TOPEX is analyzed in the tropical Pacific Ocean by way of assimilation into a wind-driven, reduced-gravity, shallow water model using an approximate Kalman filter and smoother. The analysis results in an optimal fit of the dynamic model to the observations, providing it dynamically consistent interpolation of sea level and estimation of the circulation. Nearly 80% of the expected signal variance is accounted for by the model within 20 deg of the equator, and estimation uncertainty is substantially reduced by the voluminous observation. Notable features resolved by the analysis include seasonal changes associated with the North Equatorial Countercurrent and equatorial Kelvin and Rossby waves. Significant discrepancies are also found between the estimate and TOPEX measurements, especially near the eastern boundary. Improvements in the estimate made by the assimilation are validated by comparisons with independent tide gauge and current meter observations. The employed filter and smoother are based on approximately computed estimation error covariance matrices, utilizing a spatial transformation and an symptotic approximation. The analysis demonstrates the practical utility of a quasi-optimal filter and smoother.

  17. Future high sea levels in south Sweden

    SciTech Connect

    Blomgren, S.H.; Hanson, H.

    1997-12-31

    An estimation of future mean high water levels in Oeresund and the southwest Baltic Sea is presented together with a discussion of probable consequences for Falsterbo Peninsula, a trumpet-shaped sandy formation of some 25 km{sup 2} size situated in the very southwest corner of Sweden. A literature review coupled with sea-level measurements and observations made in the area every four hours since October 1945 are given and comprise the base for the present analysis.

  18. A Late Pleistocene sea level stack

    NASA Astrophysics Data System (ADS)

    Spratt, R. M.; Lisiecki, L. E.

    2015-08-01

    Late Pleistocene sea level has been reconstructed from ocean sediment core data using a wide variety of proxies and models. However, the accuracy of individual reconstructions is limited by measurement error, local variations in salinity and temperature, and assumptions particular to each technique. Here we present a sea level stack (average) which increases the signal-to-noise ratio of individual reconstructions. Specifically, we perform principal component analysis (PCA) on seven records from 0-430 ka and five records from 0-798 ka. The first principal component, which we use as the stack, describes ~80 % of the variance in the data and is similar using either five or seven records. After scaling the stack based on Holocene and Last Glacial Maximum (LGM) sea level estimates, the stack agrees to within 5 m with isostatically adjusted coral sea level estimates for Marine Isotope Stages 5e and 11 (125 and 400 ka, respectively). When we compare the sea level stack with the δ18O of benthic foraminifera, we find that sea level change accounts for about ~40 % of the total orbital-band variance in benthic δ18O, compared to a 65 % contribution during the LGM-to-Holocene transition. Additionally, the second and third principal components of our analyses reflect differences between proxy records associated with spatial variations in the δ18O of seawater.

  19. Statistical relationships between local sea level and weather with Florida-Bahamas cable and Pegasus measurements of Florida Current volume transport

    NASA Astrophysics Data System (ADS)

    Maul, George A.; Mayer, Dennis A.; Bushnell, Mark

    1990-03-01

    Straits of Florida sea level is studied as a measure of Florida Current volume transport because sea level provides an independent time series both (1) for detecting changes in the calibration of the Florida-Bahamas submarine cable which has been operating since 1982, and (2) as a measure of the strength of the Gulf Stream System dating to the 1930s when cable measurements were not available. Accordingly, tide gauge records from Haulover Beach (Miami) and Lake Worth, Florida, and from Cat Cay and Settlement Point, The Bahamas, together with Miami weather and cable voltage, are correlated with each other and with discrete volume transport estimated from all Pegasus data taken during the intensive 1982-1984 Subtropical Atlantic Climate Studies (STACS) observations. Time domain linear correlation coefficients between these 132 Pegasus values and cable voltage observations, Cat Cay minus Haulover Beach sea level, and Haulover Beach sea level only, are 0.91, 0.55, and -0.76, respectively, but for the 1982-1988 time series, Cat Cay minus Haulover Beach is better correlated with cable observations (0.62) than is Haulover Beach alone (-0.44). Frequency domain modeling computations reveal that the sea level and cable data are organized in such a way that most of their energy lies below frequencies of 30-1 cycles per day (cpd). In a subseasonal band (up to and including the semiannual frequency) 49% of the cable energy and 59% of the Haulover Beach energy can be accounted for using 30-day low-passed data. A subseasonal frequency response function has been tentatively identified that relates both Florida sea level and Bahamas-Florida sea level difference to cable observations and can successfully account for more than 60% of the observed cable variance (standard error is ±1×106 m3 s-1). Further, negative Florida sea level only and Bahamas-Florida sea level difference have different phase relationships with cable observations; it is suggested that steric effects could be responsible for the phase shifts.

  20. Regional sea level variability in the Bohai Sea, Yellow Sea, and East China Sea

    NASA Astrophysics Data System (ADS)

    Cheng, Yongcun; Plag, Hans-Peter; Hamlington, Benjamin D.; Xu, Qing; He, Yijun

    2015-12-01

    The regional sea level variability in the Bohai Sea (BS), Yellow Sea (YS) and East China Sea (ECS) is investigated based on tide gauge, satellite altimeter data and an independent oceanic general circulation model for the Earth Simulator (OFES) model outputs. It is found that atmospheric forcing significantly affects local sea level variability in the BS and YS and local sea level variability at the Southern ECS is highly correlated with along-shore currents. Particularly, the annual sea level fluctuations potentially change inundation risk and the frequency and magnitude of flooding in regions with high annual sea level. Hence, the cyclostationary empirical orthogonal function (CSEOF) analysis is carried out to investigate the variations of annual sea level cycle amplitude. Similar spatial distribution characteristics of annual sea level amplitude fluctuations are presented from satellite altimeter data and model outputs. The variability of annual sea level amplitude estimated from the satellite altimeter data agrees well with that from the tide gauge data, and positively (negatively) correlates with Southern Oscillation Index (Pacific Decadal Oscillation). The OFES model, however, underestimates the fluctuation of the annual cycle. After removing the annual signal, the low-passed (i.e., 13-month running mean) tide gauge data shows high correlations with SOI and PDO on time scales over 8 years in the BS and ECS.

  1. Solution notches, earthquakes, and sea level, Haiti

    NASA Astrophysics Data System (ADS)

    Schiffman, C. R.; Mildor, B. S.; Bilham, R. G.

    2010-12-01

    Shortly after the 12 January 2010 Haiti earthquake, we installed an array of five tide gauges to determine sea level and its variability in the region of uplifted corals on the coast SW of Leogane, Haiti, that had been uplift ≤30 cm during the earthquake. Each gauge consists of a pressure transducer bolted 50-80 cm below mean sea level, which samples the difference between atmospheric pressure and sea pressure every 10 minutes. The data are transmitted via the Iridium satellite and are publically available with a latency of 10 minutes to 2 hours. The measurements reveal a maximum tidal range of ≈50 cm with 2-4 week oscillations in mean sea level of several cm. Sea slope, revealed by differences between adjacent gauges, varies 2-5 cm per 10 km at periods of 2-5 weeks, which imposes a disappointing limit to the utility of the gauges in estimating post seismic vertical motions. A parallel study of the form and elevation of coastal notches and mushroom rocks (rocks notched on all sides, hence forming a mushroom shape), along the coast west of Petit Goave suggests that these notches may provide an uplift history of the region over the past several hundreds of years. Notch sections in two areas were contoured, digitized, and compared to mean sea level. The notches mimic the histogram of sea level, suggesting that they are formed by dissolution by acidic surface waters. Notches formed two distinct levels, one approximately 58 cm above mean sea level, and the other approximately 157 cm above mean sea level. Several landslide blocks fell into the sea during the 2010 earthquake, and we anticipate these are destined for conversion to future mushroom rocks. Surfaces have been prepared on these blocks to study the rate of notch formation in situ, and samples are being subjected to acid corrosion in laboratory conditions, with the hope that the depth of notches may provide an estimate of the time of fall of previous rocks to help constrain the earthquake history of this area. A provisional interpretation is that this segment of the Haiti coastline was subjected to Intensity VIII shaking and rose 58 cm in the January 2010 earthquake. A previous earthquake presumably caused uplift of ≈1 m at this location, but we cannot constrain its date at present.

  2. A Late Pleistocene sea level stack

    NASA Astrophysics Data System (ADS)

    Spratt, Rachel M.; Lisiecki, Lorraine E.

    2016-04-01

    Late Pleistocene sea level has been reconstructed from ocean sediment core data using a wide variety of proxies and models. However, the accuracy of individual reconstructions is limited by measurement error, local variations in salinity and temperature, and assumptions particular to each technique. Here we present a sea level stack (average) which increases the signal-to-noise ratio of individual reconstructions. Specifically, we perform principal component analysis (PCA) on seven records from 0 to 430 ka and five records from 0 to 798 ka. The first principal component, which we use as the stack, describes ˜ 80 % of the variance in the data and is similar using either five or seven records. After scaling the stack based on Holocene and Last Glacial Maximum (LGM) sea level estimates, the stack agrees to within 5 m with isostatically adjusted coral sea level estimates for Marine Isotope Stages 5e and 11 (125 and 400 ka, respectively). Bootstrapping and random sampling yield mean uncertainty estimates of 9-12 m (1σ) for the scaled stack. Sea level change accounts for about 45 % of the total orbital-band variance in benthic δ18O, compared to a 65 % contribution during the LGM-to-Holocene transition. Additionally, the second and third principal components of our analyses reflect differences between proxy records associated with spatial variations in the δ18O of seawater.

  3. An approach to investigate new particle formation in the vertical direction on the basis of high time-resolution measurements at ground level and sea level

    NASA Astrophysics Data System (ADS)

    Meng, He; Zhu, Yujiao; Evans, Greg J.; Yao, Xiaohong

    2015-02-01

    In this study, we investigated new particle formation (NPF) in the vertical direction using high time-resolution (1 s) measurements made by Fast Mobility Particle Sizers at ground level and at sea level. The coefficient of variation (CV), i.e., the ratio of standard deviation to mean value for <100-nm particle number concentration (N100) in every 30 s, is introduced as a metric to distinguish horizontal and vertical transport of atmospheric particles. We first examined the CV metric using the data collected at a semi-urban site in Toronto during the summer of 2007. The 50th and 95th percentiles of CVs associated with horizontal transport were 1-13 times smaller than those during strong vertical transport. We then compared the N100, GMD55 (geometric mean diameter of <55-nm particles) and GMD100 corresponding to the 0-5th percentiles of CVs with those corresponding to the 95-100th percentiles of CVs in five NPF events. The comparative results are discussed in terms of different formation and growth rates in the vertical direction. The similar analysis was also conducted in various marine atmospheres. We found that the CV metric can improve our understanding of NPF in the vertical direction.

  4. Effect of river runoff on sea level from in-situ measurements and numerical models in the Bay of Biscay

    NASA Astrophysics Data System (ADS)

    Laiz, Irene; Ferrer, Luis; Plomaritis, Theocharis A.; Charria, Guillaume

    2014-08-01

    Daily time series of in-situ tide gauge records and river runoff data were analysed to investigate the contribution of river discharge storm events to sea level in the Bay of Biscay. Three main river systems were considered for this study, representing cases of small (Nervión, 1900 km2), medium (Adour, 16,880 km2) and large (Gironde, 84,811 km2) watershed basins. Typical storms correspond to water discharge rates of 150, 700, and 1100 m3 s-1 from the Nervión, Adour, and Gironde rivers, respectively. The effect of these events on daily mean sea level was evaluated using two different approaches: (1) through the analysis of time series of tide gauges placed within the river mouths; and (2) through numerical simulations using the ROMS model (Regional Ocean Modeling System). The three selected tide gauges are located at Bilbao (Spain) for the Nervión river, Boucau-Bayonne (France) for the Adour river and Port-Bloc (France) for the Gironde river. River runoff extreme events were more notable at the two tide gauges located within the largest rivers, namely, Adour and Gironde, where approximately 13% and 53.6% of the pressure-adjusted sea-level variance was explained by those events. The results obtained from the ROMS simulations suggest that the main effect of river discharge storm events occurs as a response to the input of lower salinity water. This plume of overlaying less dense water would produce a sea-level increase around the river mouth and along the coast, suggesting the generation of a coastal density current through the balance between the Coriolis force and the cross-shore pressure gradient. The main area of influence of the selected river discharges was confined to the river mouth for the Nervión, but extended up to approximately 28 km (33 km) offshore for the Adour (Gironde) river, before turning northward to flow as a density current along the coast.

  5. Sea-Level Projections from the SeaRISE Initiative

    NASA Technical Reports Server (NTRS)

    Nowicki, Sophie; Bindschadler, Robert

    2011-01-01

    SeaRISE (Sea-level Response to Ice Sheet Evolution) is a community organized modeling effort, whose goal is to inform the fifth IPCC of the potential sea-level contribution from the Greenland and Antarctic ice sheets in the 21st and 22nd century. SeaRISE seeks to determine the most likely ice sheet response to imposed climatic forcing by initializing an ensemble of models with common datasets and applying the same forcing to each model. Sensitivity experiments were designed to quantify the sea-level rise associated with a change in: 1) surface mass balance, 2) basal lubrication, and 3) ocean induced basal melt. The range of responses, resulting from the multi-model approach, is interpreted as a proxy of uncertainty in our sea-level projections. http://websrv.cs .umt.edu/isis/index.php/SeaRISE_Assessment.

  6. Late Cretaceous sea level from a paleoshoreline

    SciTech Connect

    McDonough, K.J.; Cross, T.A. )

    1991-04-10

    The contemporary elevation of a Late Cenomanian ({approx}93 Ma) shoreline was determined at five localities along the tectonically stable, eastern margin of the Cretaceous Western Interior Seaway, North America. This shoreline, represented by marine-to-nonmarine facies transitions in strata of the Greenhorn sequence (UZA-2 cycle of Haq et al. (1987)), was identified from outcrop and borehole data. Biostratigraphic zonations constrained the geologic age at each locality. Sequence stratigraphic correlations, based on identifying discrete progradational units and the surfaces that separate them, were used to refine age correlations to better than 100 kyr between localities. A single Cenomanian shoreline was correlated within a single progradational unit, and its elevation was determined at five localities. This paleostrandline occurs 265-286m above present-day sea level, at an average elevation of 276 m. Isostatic and flexural corrections were applied to remove the effects of postdepositional vertical movement, including sediment compaction by loading, uplift due to erosion, and glacial loading and rebound. Errors inherent in each measurement and each correction were estimated. Corrections and their cumulative error estimates yield a Late Cenomanian elevation of 269{plus minus}87 m above present sea level. The corrected elevation approximates sea level at 93 Ma and provides a measure of Late Cenomanian eustasy prior to the Early Turonian highstand. Establishing the absolute value for eustasy at a single point in geologic time provides a frame of reference for calibrating relative sea level curves, as well as constraining the magnitudes of tectonic subsidence, sediment flux, and other variables that controlled water depth and relative sea level.

  7. Sea level trends and interannual variability in the Caribbean Sea

    NASA Astrophysics Data System (ADS)

    Torres, R.; Tsimplis, M.

    2012-04-01

    Sea level trends and interannual variability has been investigated in the Caribbean Sea using altimetry and tide gauge time series from 19 stations. Relative sea level trends range between -2.0 and 10.7 mm/y depending on the length of the available record. Records from stations longer than 40 years converge toward values between 1.2 - 5.2 mm/yr, still a significant range which in some stations is less and in some other significantly larger than the global average. The longest station, Cristobal (102 years) shows a trend of 1.9 mm/yr and, in addition a significant acceleration of 1.6±0.3 mm/y/cy. The observed sea level trends are not affected by the atmospheric pressure effect, within the levels of significance. They are also the same (within the levels of significance) at all seasons. Altimetry shows trends (over 18 years of data) with values up to 5.2 mm/y. In some areas the values are statistically insignificant, but at no areas statistically significant negative values are found. Steric trends from the top 800 m (over the period of altimetric observations) have a basin average trend of 1 mm/y, but it shows large spatial variability with negative trends of -7 mm/y in the Yucatan Basin and positive trends up to 4.9 mm/y in the Venezuela Basin. Decadal trends were found to vary significantly at tide-gauge records as well as altimetric and steric measurements. We further explore the residual interannual variability by comparison with surface wind and climatic indices. This analysis is supported by the Lloyd's Register Trust Fund project Marine Extremes.

  8. Comparison of sea-level measurements using microwave radar and subsurface pressure gauge deployed in Mandovi estuary in Goa, central west coast of India

    NASA Astrophysics Data System (ADS)

    Mehra, Prakash; Agarvadekar, Yogesh; Luis, Ryan; Nadaf, Lalsab

    2012-06-01

    Data from the radar and an absolute pressure gauge collected from Verem, Goa over a period of one year- January, 2009 to May, 2010 is used to carry out the comparative studies. The root mean square difference between the estimated sea level using radar and pressure gauge with atmospheric pressure correction is ~ 2.6 cm. The harmonic analysis over the two time series produces similar residuals and tidal constituents. The results from the study indicate the importance of concurrent measurement of atmospheric pressure along with sub-bottom absolute pressure gauge. The radar gauge has advantages over other type of gauges with regard to easy installation, maintenance and also sea level measurements are absolute and could be given precedence in future applications.

  9. Sea-level projections from the SeaRISE initiative

    NASA Astrophysics Data System (ADS)

    nowicki, S.; Bindschadler, R.; SeaRISE Team

    2011-12-01

    SeaRISE (Sea-level Response to Ice Sheet Evolution) is a community organized modeling effort, whose goal is to inform the fifth IPCC of the potential sea-level contribution from the Greenland and Antarctic ice sheets in the 21st and 22nd century. SeaRISE seeks to determine the most likely ice sheet response to imposed climatic forcing by initializing an ensemble of models with common datasets and applying the same forcing to each model. Sensitivity experiments were designed to quantify the sea-level rise associated with a change in: 1) surface mass balance, 2) basal lubrication, and 3) ocean induced basal melt. The range of responses, resulting from the multi-model approach, is interpreted as a proxy of uncertainty in our sea-level projections.

  10. Benchmarking and testing the "Sea Level Equation

    NASA Astrophysics Data System (ADS)

    Spada, G.; Barletta, V. R.; Klemann, V.; van der Wal, W.; James, T. S.; Simon, K.; Riva, R. E. M.; Martinec, Z.; Gasperini, P.; Lund, B.; Wolf, D.; Vermeersen, L. L. A.; King, M. A.

    2012-04-01

    The study of the process of Glacial Isostatic Adjustment (GIA) and of the consequent sea level variations is gaining an increasingly important role within the geophysical community. Understanding the response of the Earth to the waxing and waning ice sheets is crucial in various contexts, ranging from the interpretation of modern satellite geodetic measurements to the projections of future sea level trends in response to climate change. All the processes accompanying GIA can be described solving the so-called Sea Level Equation (SLE), an integral equation that accounts for the interactions between the ice sheets, the solid Earth, and the oceans. Modern approaches to the SLE are based on various techniques that range from purely analytical formulations to fully numerical methods. Despite various teams independently investigating GIA, we do not have a suitably large set of agreed numerical results through which the methods may be validated. Following the example of the mantle convection community and our recent successful Benchmark for Post Glacial Rebound codes (Spada et al., 2011, doi: 10.1111/j.1365-246X.2011.04952.x), here we present the results of a benchmark study of independently developed codes designed to solve the SLE. This study has taken place within a collaboration facilitated through the European Cooperation in Science and Technology (COST) Action ES0701. The tests involve predictions of past and current sea level variations, and 3D deformations of the Earth surface. In spite of the signi?cant differences in the numerical methods employed, the test computations performed so far show a satisfactory agreement between the results provided by the participants. The differences found, which can be often attributed to the different numerical algorithms employed within the community, help to constrain the intrinsic errors in model predictions. These are of fundamental importance for a correct interpretation of the geodetic variations observed today, and particularly for the evaluation of climate-driven sea level variations.

  11. How the climate drives sea-level changes

    NASA Astrophysics Data System (ADS)

    Milne, Glenn

    2008-04-01

    Sea-level change associated with climate change involves various interactions between different components of the Earth system - primarily oceans, ice sheets and the solid Earth. As a consequence, sea-level science is highly multi- and interdisciplinary, requiring collaboration between scientists who measure and model properties of and processes within these various subsystems. This paper provides a broad and cursory glimpse into the processes underlying climate-driven sea-level change. A key message of this paper is that, contrary to popular belief, climate-driven sea-level change is not spatially uniform. This is a doubled-edged sword: it complicates the processes of producing well-constrained estimates of future sea-level rise at regional to local scales, but it provides the opportunity to better understand past climate change through modelling observations of sea-level changes.

  12. Scientific reticence and sea level rise

    NASA Astrophysics Data System (ADS)

    Hansen, J. E.

    2007-04-01

    I suggest that a 'scientific reticence' is inhibiting the communication of a threat of a potentially large sea level rise. Delay is dangerous because of system inertias that could create a situation with future sea level changes out of our control. I argue for calling together a panel of scientific leaders to hear evidence and issue a prompt plain-written report on current understanding of the sea level change issue.

  13. Greenhouse effect, sea level rise, and coastal zone management

    SciTech Connect

    Titus, J.G.

    1986-01-01

    Increasing concentrations of carbon dioxide and other gases are expected to warm the earth several degrees in the next century by a mechanism known as the greenhouse effect. Such a warming could cause sea level to rise two to five feet by expanding ocean water, melting mountain glaciers, and perhaps eventually causing polar glaciers to melt and slide into the oceans. A rise in sea level of even three feet could cause substantial erosion of beaches and coastal wetlands, increased flooding, and intrusion of salt water into rivers, bays, and aquifer. Fortunately, many of the adverse consequences can be avoided by taking timely measures in anticipation of sea level rise. Nevertheless, many coastal zone managers are reluctant to take these measures until the prospect of sea level rise becomes more certain. This article examines the implications of future sea level rise and identifies anticipatory measures that may be appropriate today in spite of current uncertainties. 46 references, 4 figures, 1 table.

  14. Coastal eolian landforms and sea level fluctuations

    NASA Astrophysics Data System (ADS)

    Badyukova, E. N.; Solovieva, G. D.

    2015-02-01

    This paper is dedicated to correlation of the formation of coastal marine landforms with sea level fluctuations and climate changes in the last millennium using the southeastern Baltic region as an example. The morphological analysis of spits and historical evidence reveal three sea level oscillations in its evolution. It is shown that the sea level rise against the background of the sandy material excess in the coastal zone and optimum angle of the prevailing land-directed wind are the main factors responsible for accumulation of the thickest sandy formations. The recent climate warming and related sea level rise provoke global destabilization of coastal dune massifs.

  15. Sea level rise and its coastal impacts

    NASA Astrophysics Data System (ADS)

    Cazenave, Anny; Cozannet, Gonéri Le

    2014-02-01

    Global warming in response to accumulation of human-induced greenhouse gases inside the atmosphere has already caused several visible consequences, among them increase of the Earth's mean temperature and ocean heat content, melting of glaciers, and loss of ice from the Greenland and Antarctica ice sheets. Ocean warming and land ice melt in turn are causing sea level to rise. Sea level rise and its impacts on coastal zones have become a question of growing interest in the scientific community, as well as in the media and public. In this review paper, we summarize the most up-to-date knowledge about sea level rise and its causes, highlighting the regional variability that superimposes the global mean rise. We also present sea level projections for the 21st century under different warming scenarios. We next address the issue of the sea level rise impacts. We question whether there is already observational evidence of coastal impacts of sea level rise and highlight the fact that results differ from one location to another. This suggests that the response of coastal systems to sea level rise is highly dependent on local natural and human settings. We finally show that in spite of remaining uncertainties about future sea levels and related impacts, it becomes possible to provide preliminary assessment of regional impacts of sea level rise.

  16. The social values at risk from sea-level rise

    SciTech Connect

    Graham, Sonia; Barnett, Jon; Fincher, Ruth; Hurlimann, Anna; Mortreux, Colette; Waters, Elissa

    2013-07-15

    Analysis of the risks of sea-level rise favours conventionally measured metrics such as the area of land that may be subsumed, the numbers of properties at risk, and the capital values of assets at risk. Despite this, it is clear that there exist many less material but no less important values at risk from sea-level rise. This paper re-theorises these multifarious social values at risk from sea-level rise, by explaining their diverse nature, and grounding them in the everyday practices of people living in coastal places. It is informed by a review and analysis of research on social values from within the fields of social impact assessment, human geography, psychology, decision analysis, and climate change adaptation. From this we propose that it is the ‘lived values’ of coastal places that are most at risk from sea-level rise. We then offer a framework that groups these lived values into five types: those that are physiological in nature, and those that relate to issues of security, belonging, esteem, and self-actualisation. This framework of lived values at risk from sea-level rise can guide empirical research investigating the social impacts of sea-level rise, as well as the impacts of actions to adapt to sea-level rise. It also offers a basis for identifying the distribution of related social outcomes across populations exposed to sea-level rise or sea-level rise policies.

  17. Measuring the mass balance and contribution to sea level rise of North American glaciers using remote sensing techniques

    NASA Astrophysics Data System (ADS)

    Vanlooy, Jeffrey Adam

    Volume and surface elevation changes were calculated for six icefields throughout Alaska and British Columbia by differencing Digital Elevation Models (DEMs) that represent glacial elevations from different time periods. For the Harding Icefield on the Kenai Peninsula in southcentral Alaska, United States Geological Survey (USGS) DEMs from the 1950s were differenced with Shuttle Radar Topographic Mission (SRTM) DEMs from 2000 (effective 1999 elevations). Results indicated that the icefield had a volume loss of -72.1 +/-15.0 km3, which equates to 0.0033 +/- 0.0006 mm y-1 of sea level rise contribution. Along with these results, Light Detecting and Ranging (Lidar) elevation data of 13 Harding Icefield glaciers from the mid-1990s provided a third elevation data set for comparison with the USGS and SRTM DEMs. The results from these surface elevation change calculations indicated that surface elevation change rates increased by 1.5 times from the mid-1990s to 1999 (-0.72 +/- 0.13 m y-1) as compared to the 1950s to the mid-1900s (-0.47 +/- 0.01 m y-1). In southwest British Columbia, five icefields were studied: Monarch, Ha-Iltzuk, Mt. Waddington area, Homathko, and Lillooet. Terrain Resource Information Management (TRIM) DEMs from the mid-1980s were differenced from the SRTM DEMs to calculate the volume and surface elevation change of the five icefields. Results from these calculations indicate that between the mid-1980s and 1999 the total volume change of the five icefields was a loss of -47.72 +/- 14.62 km3, which equates to a potential sea level rise contribution of 0.0077 +/-0.0021 mm y-1. A DEM of a third time period was produced by kriging elevation points derived from 1970s topographic maps, and used to calculate volume and surface elevation changes of Ha-Iltzuk Icefield for the time period of 1970 to the mid-1980s. The results of this analysis indicate that Ha-Iltzuk Icefield had a volume loss of -5.87 +/- 2.89 km3 and a surface elevation change rate of -0.58 +/- 0.30 m y-1. This also indicates that the surface elevation change rate of Ha-Iltzuk Icefield has increased by 3.5 times when compared to the surface elevation change rate between the mid-1980s and 1999 (-2.03 +/- 0.47 m-1). If the increase in thinning rates experienced by the Harding and Ha-Iltzuk Icefields continues, these and other similarly sized icefields at the same latitudes in North America are likely to be completely melted within the next 500 years.

  18. Regional variability in sea level trends since 1950: comparison between sea level hindcasts from the CNRM coupled climate model with different forcings, past sea level reconstructions and observed steric sea level

    NASA Astrophysics Data System (ADS)

    Meyssignac, B.; Llovel, W.; Salas-Y-Mélia, D.; Cazenave, A. A.

    2010-12-01

    Satellite altimetry has revealed important regional variability in sea level trends for the past >15 years. Ocean re analyses available for the past 4-5 decades also display non uniform spatial trend patterns in sea level, significantly different than those observed over the last 15 years. In situ hydrographic measurements and ocean general circulation model (OGCM) outputs indicate that non uniform thermosteric and halosteric expansion are the main causes of sea level regional variability. In this study, we analyse sea level outputs of the CNRM coupled climate model runs over the past ~150 years, focusing on the last 50 years of the computations. Different cases corresponding to different forcing factors are investigated (solar + volcanic + greenhouse gases emissions forcing and solar + volcanic forcing) and compared to the internal natural variability. We look at trend patterns and Empirical Orthogonal Function decompositions of the computed gridded sea level time series in order to compare the dominant modes of variability of each data set. We also compare the coupled climate outputs with reconstructed sea level grids over the past 50-60 years based on tide gauge data and gridded sea level from different sources (satellite altimetry and OGCMs) (testing different reconstruction methods) and steric sea level grids based on historical in situ measurements of ocean temperature and salinity. These analyses allow assessing the different past sea level reconstructions methods and regional sea level hindcasts from the CNRM coupled climate model. The primary objective of these investigations is an attempt to detect the fingerprint of greenhouse gas emissions on the regional variability of sea level.

  19. The key role of vertical land motions in coastal sea level variations: A global synthesis of multisatellite altimetry, tide gauge data and GPS measurements

    NASA Astrophysics Data System (ADS)

    Pfeffer, Julia; Allemand, Pascal

    2016-04-01

    This study aims to quantify the vertical motions driving the decadal coastline mobility and their uncertainty at global scale. Multisatellite altimetry is combined with tide gauges and Global Positioning System (GPS) observations to evaluate the marine and crustal components of relative sea level variations. Vertical land motions and sea level variations are estimated simultaneously over the past 20 years for a network of 886 ground stations, with accuracies better than 1.7 mm/yr. The ALTIGAPS database present significant interest both by its technical characteristics (global coverage, larger number of sites, longer period of observation, improved accuracy) and by the novelty of the applications empowered. ALTIGAPS offers the opportunity to look independently into the recent dynamic processes affecting the ocean and the interior of the Earth. Here, the role of vertical land motions in relative sea level variations is explored to better understand the natural hazards associated with sea level rise in coastal areas. Global evidence for the local variability in vertical land motions is provided, which may either amplify or attenuate the apparent rise of the sea at the coast. A set of 182 potential vulnerable localities are identified by large coastal subsidence (>1.5 mm/yr) which increases by several times the effects of climate-induced sea level rise. For coastal management purposes, both marine (absolute sea level variations) and crustal (vertical land motions) components of vertical coastal motions (relative sea level variations) should therefore be accounted for.

  20. Sea Level Rise in Tampa Bay

    NASA Astrophysics Data System (ADS)

    Cronin, Thomas; Edgar, N. Terence; Brooks, Gregg; Hastings, David; Larson, Rebekka; Hine, Albert; Locker, Stanley; Suthard, Beau; Flower, Benjamin; Hollander, David; Wehmiller, John; Willard, Debra; Smith, Shannon

    2007-03-01

    Understanding relative sea level (RSL) rise during periods of rapid climatic change is critical for evaluating modern sea level rise given the vulnerability of Antarctic ice shelves to collapse, the retreat of the world's glaciers, and mass balance trends of the Greenland ice sheet. The first-order pattern of global sea level rise following the Last Glacial Maximum (LGM, ~21,000 years ago) is well established from coral, continental shelf, and other records and has been integrated into a global ICE-5G model of glacio-isostatic adjustment (GIA). However, uncertainty introduced by paleo water depth of sea level indicators, radiocarbon chronology (i.e., reservoir corrections for marine shell dates), postglacial isostatic adjustment, and other processes affecting vertical position of former shorelines produces scatter in RSL curves, limiting our knowledge of sea level rise during periods of rapid glacial decay.

  1. The thickness history of the northern sector of the Laurentide Ice Sheet: an assessment of glacial isostatic adjustment models, sea-level measurements, and vertical land motion rates

    NASA Astrophysics Data System (ADS)

    Simon, K. M.; James, T. S.; Henton, J. A.; Dyke, A.

    2014-12-01

    The fit of glacial isostatic adjustment (GIA) model predictions to 24 relative sea-level histories and an additional 18 present-day GPS-measured vertical land motion rates constrains the thickness and volume history of the central and northern Laurentide Ice Sheet. The predictions of the best-fit GIA model indicate respective peak ice thicknesses west and east of Hudson Bay of 3.4-3.6 km and approximately 4 km. These values represent, respectively, a large decrease, and a moderate increase, to the load thickness compared to ICE-5G. This result is generally consistent with other GIA studies focussing on space-geodetic constraints. The large reduction to the ice load west of Hudson Bay also reduces the vertical mantle response along the margins of the load centre, which improves the fit to relative sea-level data from the southern Canadian Arctic Archipelago. The fit of GIA model predictions to relative sea-level data from the Baffin Sector of the Laurentide Ice Sheet indicate peak ice thicknesses there of 1.2-1.3 km, a modest reduction compared to ICE-5G. On Baffin Island, the modelled elastic crustal response of the Earth to present-day ice mass changes is large. Accounting for this effect improves the agreement between GPS measurements of vertical crustal motion and the GIA model predictions. However, work is needed to incorporate more detailed observations and modelling of present-day changes to glaciers and ice caps. Overall, the fit to the data is most strongly improved in the region west of Hudson Bay (the χ2 RSL misfit is reduced by a factor of ~4) although the entire revised reconstruction for the central and northern Laurentide Ice Sheet provides an improved fit to both the regional RSL data (the cumulative χ2 misfit is reduced by a factor of >2) and the GPS data (the RMS misfit is reduced by a factor of 9).

  2. Wave transformation across coral reefs under changing sea levels

    NASA Astrophysics Data System (ADS)

    Harris, Daniel; Power, Hannah; Vila-Conejo, Ana; Webster, Jody

    2015-04-01

    The transformation of swell waves from deep water across reef flats is the primary process regulating energy regimes in coral reef systems. Coral reefs are effective barriers removing up to 99% of wave energy during breaking and propagation across reef flats. Consequently back-reef environments are often considered low energy with only limited sediment transport and geomorphic change during modal conditions. Coral reefs, and specifically reef flats, therefore provide important protection to tropical coastlines from coastal erosion and recession. However, changes in sea level could lead to significant changes in the dissipation of swell wave energy in coral reef systems with wave heights dependent on the depth over the reef flat. This suggests that a rise in sea level would also lead to significantly higher energy conditions exacerbating the transgressive effects of sea level rise on tropical beaches and reef islands. This study examines the potential implications of different sea level scenarios on the transformation of waves across the windward reef flats of One Tree Reef, southern Great Barrier Reef. Waves were measured on the reef flats and back-reef sand apron of One Tree Reef. A one-dimensional wave model was calibrated and used to investigate wave processes on the reef flats under different mean sea level (MSL) scenarios (present MSL, +1 m MSL, and +2 m MSL). These scenarios represent both potential future sea level states and also the paleo sea level of the late Holocene in the southern Great Barrier Reef. Wave heights were shown to increase under sea level rise, with greater wave induced orbital velocities affecting the bed under higher sea levels. In general waves were more likely to entrain and transport sediment both on the reef flat and in the back reef environment under higher sea levels which has implications for not only forecasted climate change scenarios but also for interpreting geological changes during the late Holocene when sea levels were 1-2 m higher than present.

  3. Using Sea Level Change as a Climate Indicator

    NASA Astrophysics Data System (ADS)

    Masters, D. S.; Nerem, R. S.

    2014-12-01

    Sea level rise is one the more important risks due to climate change. Multiple satellite altimeters flying on the same repeating ground track have allowed estimation of global and regional sea level for the past 20 years, and the time series has yielded information about how sea level is responding to climate change. Due to the duration, consistency, and inter-calibration of the altimeter measurements, the time series is now considered a climate data record. The time series has also shown the strong dependence of sea level on interannual signals such as the ENSO and PDO. Global mean sea level change as estimated by the altimeters is arguably one of the most sensitive indicators of climate change because it varies almost entirely due to thermal expansion/contraction and the exchange of water between the land and oceans. Contributions to the latter include melting land ice and changes in the hydrologic cycle. While thermal expansion does not vary greatly on interannual time-scales, variations in the global hydrologic cycle and land ice melt can contribute to large variations in the sea level record. Isolating and understanding the causes and scales of these variations is important in interpreting the observed global and regional sea level change, especially for decision-makers assessing risk and planning for adaptation and/or mitigation. Since 1992, satellite altimeter measurements from the TOPEX/Poseidon and Jason missions, have been providing precise estimates of sea level change between ±66° latitude every 10 days. We have been using these measurements to monitor both global average and regional sea level change. The GRACE mission has provided monthly estimates of the time-varying gravity field for the last 10 years. These measurements can estimate variations in global ocean mass, mass changes in the polar ice sheets and mountain glaciers, as well as changes in the land surface water storage. These data sets can be used to inform us about the sea level change over most of the Earth and the causes/sources of this change. With this information, we can gauge how the Earth is responding to climate change, map the regional changes in sea level, and improve our projections of future sea level change and its impacts. We will discuss both the benefits and challenges of using satellite-measured sea level change as a climate indicator.

  4. Sea level change: a philosophical approach

    NASA Astrophysics Data System (ADS)

    Leinfelder, R.; Seyfried, H.

    1993-07-01

    The present Cenozoic era is an ‘icehouse’ episode characterized by a low sea level. Since the beginning of the industrial revolution, the human race has been emitting greenhouse gases, increasing the global atmospheric temperature, and causing a rise in sea level. If emissions continue to increase at the present rate, average global temperatures may rise by 1.5°C by the year 2050, accompanied by a rise of about 30 cm in sea level. However, the prediction of future climatic conditions and sea level is hampered by the difficulty in modelling the interactions between the lithosphere, kryosphere, biosphere and atmosphere; in addition, the buffering capacity of our planet is still poorly understood. As scientists cannot offer unambiguous answers to simple questions, sorcerer's apprentices fill in the gaps, presenting plans to save planet without inconveniencing us. The geological record can help us to learn about the regulation mechanisms of our planet, many of which are connected with or expressed as sea level changes. Global changes in sea level are either tectono-eustatic or glacioeustatic. Plate tectonic processes strongly control sea levels and climate in the long term. There is a strong feed-back mechanism between sea level and climate; both can influence and determine each other. Although high sea levels are a powerful climatic buffer, falling sea levels accelerate climatic accentuation, the growth of the polar ice caps and will hence amplify the drop in sea level. Important sources of fossil greenhouse gases are botanic CO2 production, CO2 released by volcanic activity, and water vapour. The latter is particularly important when the surface area of the sea increases during a rise in sea level (‘maritime greenhouse effect’). A ‘volcanogenic greenhouse effect’ (release of volcanogenic CO2) is possibly not equally important, as intense volcanic activity may take place both during icehouse episodes as well as during greenhouse episodes. The hydrosphere, land vegetation and carbonate platforms are major CO2 buffers which may both take up and release CO2. CO2 can be released from the ocean due to changes in the pCO2 caused by growth of coral reefs and by uptake of CO2-rich freshwater from karst provinces. Efficient sinks of CO2 are the weathering products of silicate rocks; long-term sinks are organic deposits caused by regional anoxic events which preferrably develop during sea level rises and highstands; and coal-bearing strata. Deposition of limestone also removes CO2 from the atmospheric-hydrospheric cycle at a long term. Biotic crises are often related to either sea-level lows or sea-level highs. Long-term sea-level lows, characteristic of glacial periods, indicate cooling as major cause of extinction. During verly long-lasting greenhouse episodes the sea level is very high, climate and circulation systems are stable and biotic crises often develop as a consequence of oxygen depletion. On land, niche-splitting, complex food web structures and general overspecialization of biota will occur. Whether the crisis is caused by a single anoxic event (e.g. in the Late Devonian) or a disturbance by an asteroid impact (e.g. the Cretaceous/Tertiary boundary), it will only trigger total collapse of an ecosystem if a large part of it was already in decline. The regulatory mechanisms and buffers are thermodynamically extremely efficient if they are given sufficient time in which to deploy their power. However, after major catastrophes the re-establishment of successful ecosystems will take millions of years. The present rate of sea level and associated temperature rise is much too fast to be compensated and buffered by the network of natural controls. It is likely that the transitional time towards a new steady state will be an extremely variable and chaotic episode of unpredictable duration.

  5. Sargasso Sea lead levels drop

    NASA Astrophysics Data System (ADS)

    Katzoff, Judith A.

    Concentrations of lead in the Sargasso Sea have decreased since at least 1979, following the phase-out of leaded gasoline in the United States that began in the early 1970s, according to a group of three scientists at the Massachusetts Institute of Technology (MIT). The Sargasso Sea is an area of the western North Atlantic Ocean centered near Bermuda, extending from about 20° to 40°N (from about the latitude of Cuba to about the latitude of North Carolina). This work will be presented on Friday morning, December 12, at the 1986 AGU Fall Meeting/ASLO Winter Meeting in San Francisco (Eos, November 4, 1986, p. 1066).

  6. Low Frequency Variations of Relative Sea Level

    NASA Astrophysics Data System (ADS)

    Douglas, B. C.; Miller, L.

    2006-12-01

    Tide gauge records of sea level display variability at all frequencies, including centennial. This variability adversely impacts estimates of sea level rise, especially for records shorter than 50-75 years. Variability of sea level at tide gauge locations on the eastern boundaries of the N. Atlantic and N. Pacific oceans is very significant even for periods > 100 years. The longest records in the N. Atlantic (Brest) and N. Pacific (San Francisco), universally used in estimates of global sea level rise, display very different behavior in the latter half of the 19th century compared to the 20th century. We show that this behavior is closely related to, but not explained by, local sea level pressure at these sites. It is possible that the disparate behavior of sea level between the 19th and 20th centuries is related to ocean basin-scale atmospheric forcing. Examination of other long records in the northern and southern hemispheres reveals in many cases a leveling off of sea level after about 1960.

  7. Understanding Sea Level Change: A Physics Based Approach

    NASA Astrophysics Data System (ADS)

    Kim, K. Y.

    2014-12-01

    Sea level change is an issue of immense importance in conjunction with global warming. The advent of satellite measurements offers a unique opportunity to address the global patterns of sea level height change associated with global warming. The rate of sea level change, however, is still uncertain due to the relatively short length of the satellite measurements, which began in 1993. In the present study, the contribution of global warming was separated from natural variability via cyclostationary EOF analysis in a sea level reconstruction dataset covering 1950-2010. Global sea level change due to the warming signal is within the range of fluctuations of the global average sea level computed directly from the data but is much less contaminated by natural variability as in the globally averaged sea level heights. A quadratic polynomial fit to the global warming signal indicates that the rate of sea level rise has increased by 0.2 mm yr-1 per decade and is 1.3 mm yr-1 as of 2010. The current rate of sea level rise is lower than that estimated from the globally averaged sea level heights by 0.2 mm yr-1 but is in the 1s range of the estimate (1.3 - 1.8 mm yr-1). Separation of the global warming mode from natural variability allow us to estimate the magnitude of natural variability and the relative significance of sea level change due to global warming. It appears that the sea level change due to global warming is, in general, comparable to natural variability in magnitude so far. Notable exceptions are over the southern tropical Indian, equatorial Pacific, tropical Atlantic, and along the extensions of the western boundary currents. Sea level rise due to warming is expected to exceed several standard deviations of natural variability by 2060 over the majority of the world oceans. This implies that coastal regions will be much more prone to disasters (such as hurricanes) due to warming-induced sea level rise.

  8. Common Era Sea-Level Change

    NASA Astrophysics Data System (ADS)

    Horton, B.; Kemp, A.; Kopp, R. E., III

    2014-12-01

    The Atlantic coast of North America provides a sedimentary record of Common Era sea levels with the resolution to identify the mechanisms that cause spatial variability in sea-level rise. This coast has a small tidal range, improving the precision of sea-level reconstructions. Coastal subsidence (from glacial isostatic adjustment, GIA) creates accommodation space that is filled by salt-marsh peat and preserves accurate and precise sea-level indicators and abundant material for radiocarbon dating. In addition, the western North Atlantic Ocean is sensitive to spatial variability in sea-level change, because of static equilibrium effects from melting of the Greenland Ice Sheet, ocean circulation and wind-driven variability in the Gulf Stream and GIA induced land-level change from ongoing collapse of Laurentide forbuldge. We reveal three distinct patters in sea-level during the Common Era along the North American Atlantic coast, likely linked to wind-driven changes in the Gulf Stream: (1) Florida, sea level is essentially flat, with the record dominated by long-term geological processes; (2) North Carolina, sea level falls to a minimum near the beginning of the second millennium, climbing to an early Little Ice Age maximum in the fifteenth century, and then declining through most of the nineteenth century; and (3) New Jersey, a sea-level maximum around 900 CE, a sea-level minimum around 1500 CE, and a long-term sea-level rise through the second half of the second millennium. We combine the salt-marsh data from North American Atlantic coast with tide-gauge records and lower resolution proxies from the northern and southern hemispheres. We apply a noisy-input Gaussian process spatio-temporal modeling framework, which identifies a long-term falling global mean sea-level (GMSL), interrupted in the middle of the 19th century by an acceleration yielding a 20th century rate of rise extremely likely (probability P = 0:95) faster than any previous century in the Common Era.

  9. Sea level forecasts using neural networks

    NASA Astrophysics Data System (ADS)

    Röske, Frank

    1997-03-01

    In this paper, a new method for predicting the sea level employing a neural network approach is introduced. It was designed to improve the prediction of the sea level along the German North Sea Coast under standard conditions. The sea level at any given time depends upon the tides as well as meteorological and oceanographic factors, such as the winds and external surges induced by air pressure. Since tidal predictions are already sufficiently accurate, they have been subtracted from the observed sea levels. The differences will be predicted up to 18 hours in advance. In this paper, the differences are called anomalies. The prediction of the sea level each hour is distinguished from its predictions at the times of high and low tide. For this study, Cuxhaven was selected as a reference site. The predictions made using neural networks were compared for accuracy with the prognoses prepared using six models: two hydrodynamic models, a statistical model, a nearest neighbor model, which is based on analogies, the persistence model, and the verbal forecasts that are broadcast and kept on record by the Sea Level Forecast Service of the Federal Maritime and Hydrography Agency (BSH) in Hamburg. Predictions were calculated for the year 1993 and compared with the actual levels measured. Artificial neural networks are capable of learning. By applying them to the prediction of sea levels, learning from past events has been attempted. It was also attempted to make the experiences of expert forecasters objective. Instead of using the wide-spread back-propagation networks, the self-organizing feature map of Kohonen, or “Kohonen network”, was applied. The fundamental principle of this network is the transformation of the signal similarity into the neighborhood of the neurons while preserving the topology of the signal space. The self-organization procedure of Kohonen networks can be visualized. To make predictions, these networks have been subdivided into a part describing the past state and another part describing the prediction. Both parts have been chosen according to methods of auto- and multiregression. A Kohonen network that has finished learning can be interpreted to be an adaptive table of such descriptions. To avoid overloading the Kohonen networks, the time series, made as complete as possible, were reduced to a learnable data set by means of two selection methods. The minimal distance method as a part of the cluster analysis was used, which selects representative temporal patterns. A novel method called circular group reduction was developed, which selects extreme patterns. This method is used as a supplement to the first one. To help the Kohonen network maintain its memory, the number of neurons and the maximum learning time were chosen according to the number of learning samples. To improve convergence, a combination of criteria was developed to break off learning, which could shown to be conform with the self-organization procedure. Kohonen networks were also applied in an autoregressive manner for the prediction of meteorological variables, especially wind. However, the quality of these predictions was inferior to those of the Marine Weather Service (SWA) in Hamburg, which is part of the German Weather Service (DWD) in Offenbach. High and low tide anomalies were predicted using Kohonen networks for multiregressions. The verbal predictions of high tide anomalies of the BSH Sea Level Forecasting Service were the most precise of all six comparison models. By using the Kohonen networks, it was even possible to improve these predictions and reduce their average error by 1 cm, from 15 to 14 cm.The precision of the Kohonen networks improved as their number of neurons increased and as their weight vectors became smaller. Since there were no major changes in the statistical properties of measurements made over mediumrange time scales, such networks that have completed learning were placed at the Sea Level Forecast Service. However, over the long term, there can be changes in these properties due to climate changes and deepening of the Elbe River. Therefore, the training process of the networks should be repeated periodically taking longer time series into consideration.

  10. Sea level changes: observations versus models

    NASA Astrophysics Data System (ADS)

    Mörner, N.-A.

    2003-04-01

    Sea level rose for glacial eustatic reasons up to about 5000 BP. After that, global sea level has been dominated by the redistribution of ocean water masses (and by that ocean-stored heat). This redistribution of water masses is driven by the interchange of angular momentum between the solid earth and the hydrosphere (in feedback coupling) primarily expressed as changes in the oceanic surface current systems. In view of this, there has been very hard to define any global eustatic signal. This is where and why a dialectic between models and observations enter the sea level debate. According to the glacial loading models, global sea level is now rising by 2.4 mm/year or 1.8 mm/year. The IPCC models have hypothesised of a very rapid rise in the near future, ranging for original wild estimates of 1-3 m in a century to the presently advocated value of 47 +37 mm in a century. The INQUA Commission on Sea Level Changes and Coastal Evolution (www.pog.su.se/sea) hosts the true world specialists on sea level research. This commission has presented an observationally based analysis of the present sea level changes and the changes to be expected in the next century. Both the glacial loading models and the ICPP scenarios are strongly contradicted by observational data for the last 100-150 years that cannot have exceeded a mean rate of 1.0-1.1 mm/year. In the last 300 years, sea level has been oscillation close to the present with peak rates in the period 1890-1930. Sea level fell between 1930 and 1950. The late 20th century lacks any sign of acceleration. Satellite altimetry indicates virtually no changes in the last decade. Therefore, observationally based predictions of future sea level in the year 2100 will give a value of +10 +10 cm (or +5 +15 cm), by this discarding model out-puts by IPCC as well as global loading models. On a regional scale, the Maldives research project has revealed that there are absolutely no signs what so ever on any on-going flooding of the Maldives. On the contrary, a distinct sea level fall is recorded at ~1970. In conclusions, there are firm observationally based reasons to free the world from the condemnation to become extensively flooded in the 21st century AD.

  11. The status of the observational sea level rise budget

    NASA Astrophysics Data System (ADS)

    Leuliette, E. W.; Miller, L.

    2009-12-01

    For decadal and longer time scales, global mean sea level change results from two major processes that alter the total volume of the ocean. Changes in the total heat content and salinity produce density (steric) changes. The exchange of water between the oceans and other reservoirs (glaciers, ice caps, and ice sheets, and other land water reservoirs) results in mass variations. With sufficient observations of sea level, ocean temperatures and salinity, and either land reservoirs or ocean mass, the total budget of global mean sea level can in principle be closed. An update to the analysis of Leuliette and Miller [2009] using an additional year and a half of steric and ocean mass components of sea level continues to show that the sea level rise budget can be closed within the range of uncertainties. Here we present five and a half years (January 2004 to July 2009) of Jason-1, Jason-2, and Envisat altimetry observations of total sea level, upper ocean steric sea level from the Argo array, and ocean mass variations inferred from GRACE gravity mission observations. For the four year period beginning mid-2005, the rate of global mean sea level has slowed to a rate of 1.4 mm/year primarily because the rate of steric sea level has flattened to near zero. For the 5.5-year period starting in 2004, total sea level rise measured by the altimeters has dropped to 1.8 ± 1.1 mm/yr, while the combination of the steric and ocean mass components is 1.4 ± 0.6 mm/year or 2.3 ± 0.6 mm/year, depending on the choice of glacial isostatic adjustment (GIA) correction. As long as concurrent observations are available, closure of the sea level budget can contribute to cross-calibration of the global ocean observing systems if errors in the analysis can be sufficiently bounded. We will focus on the current challenges in the analysis, including instrument biases, uncertainties in GIA models, and regional discrepancies that limit cross-calibration at present. Variability in total global mean sea level and its steric and mass components. The black lines are the observed (top) total sea level from Jason-1 and Jason-2, (middle) steric sea level from Argo, and (bottom) ocean mass from GRACE. The gray lines show the inferred variability from the combination of the complementary observations. A 3-month boxcar smoothing is applied to each time series.

  12. Sea level annual cycle in sea level from tide gauges, altimetry and ocean models in the Polar Seas

    NASA Astrophysics Data System (ADS)

    Cheng, Y.; Andersen, O. B.

    2012-04-01

    Lack of adequate spatial and temporal sea level observations in the Polar Seas is one of the most challenging problems in the study of sea level variation and ocean circulation in the regions. The tide gauge data captures local sea level variability with long time span of data. Most of the stations are situated at the Norwegian and Russian border and hereby only observing the easternmost part of the Polar Seas.On the other hand, obtaining satellite data in high latitude regions is generally very problematic. In the Polar Seas, sea level has a significant annual cycle over the coastal regions. In this work, Simple Ocean Data Assimilation (SODA, 1950-2008) and DRAKKAR (ORCA025-G70, 1958-2004) ocean reanalysis are used in conjunction with tide gauge data and altimetric data to investigate the sea level annual cycle in the Polar Seas. The preliminary results show that the amplitude and phase of sea level annual cycle from different data sources are quite difference with each other for the period 1950-1979 and 1980-2008 over the selected regions. To compare with the results from gridded altimetric sea level anomaly maps (ERS-1, ERS-2 and Envisat), more investigation is performed from 1993 to 2009. Moreover, the annual sea level variation from CryoSat-2 data is used for the cross validation.

  13. Groundwater depletion contributes to sea level rise

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-07-01

    Groundwater depletion is contributing substantially to sea level rise and will likely continue to do so over the next several decades, according to a new study by Wada et al. Much of the groundwater extracted for irrigation, drinking, and other uses does not wind up back in the ground but instead evaporates to the atmosphere and then returns to the surface as precipitation, which eventually makes its way to the oceans and leads to sea level rise. The authors reconstructed past groundwater depletion and its contribution to global sea level change and developed new projections for the 21st century based on models. They found that the contribution of groundwater depletion to global sea level increased from 0.035 millimeter per year in 1900 to 0.57 millimeter per year in 2000 and is projected to increase to 0.82 millimeter per year by 2050.

  14. Impact of global seismicity on sea level change assessment

    NASA Astrophysics Data System (ADS)

    Melini, D.; Piersanti, A.

    2006-03-01

    We analyze the effect of seismic activity on sea level variations by computing the time-dependent vertical crustal movement and geoid change due to coseismic deformations and postseismic relaxation effects. Seismic activity can affect both the absolute sea level, changing the Earth's gravity field and hence the geoid height, and the relative sea level (RSL), i.e., the radial distance between seafloor and geoid level. By using comprehensive seismic catalogs we assess the net effect of seismicity on tidal relative sea level measurements as well as on the global oceanic surfaces, and we obtain an estimate of absolute sea level variations of seismic origin. We modified the approach adopted in our previous analysis, considering the issue of water volume conservation by applying the sealevel equation, and we improved our computational methods, enabling us to evaluate the effect of an extremely large number of earthquakes on large grids covering the whole oceanic surface. These new potentialities allow us to perform more detailed investigations and to discover a quantitative explanation for the overall tendency of earthquakes to produce a positive global relative sea level variation. Our results confirm the finding of a previous analysis that on a global scale most of the signal is associated with a few giant thrust events and that RSL estimates obtained using tide gauge data can be sensibly affected by the seismically driven sea level signal. The recent measures of sea level obtained by satellite altimetry show a wide regional variation of sea level trends over the oceanic surface, with the largest deviations from the mean trend occurring in tectonically active regions. While our estimates of average absolute sea level variations turn out to be orders of magnitude smaller than the satellite-measured variations, we can still argue that the mass redistribution associated with aseismic tectonic processes may contribute to the observed regional variability of sea level variations. A detailed study of these tectonic contributions is important to acquire a complete understanding of the global sea level variations and will be the subject of future investigations.

  15. A Glacial Isostatic Adjustment Model for the Central and Northern Laurentide Ice Sheet based on Relative Sea-level and GPS Measurements

    NASA Astrophysics Data System (ADS)

    Simon, K. M.; James, T. S.; Henton, J. A.; Dyke, A. S.

    2016-03-01

    The thickness and equivalent global sea-level contribution of an improved model of the central and northern Laurentide Ice Sheet is constrained by 24 relative sea-level histories and 18 present-day GPS-measured vertical land motion rates. The final model, termed Laur16, is derived from the ICE-5 G model by holding the timing history constant and iteratively adjusting the thickness history, in four regions of northern Canada. In the final model, the last glacial maximum (LGM) thickness of the Laurentide Ice Sheet west of Hudson Bay was ˜3.4-3.6 km. Conversely, east of Hudson Bay, peak ice thicknesses reached ˜4 km. The ice model thicknesses inferred for these two regions represent, respectively, a ˜30% decrease and an average ˜20-25% increase to the load thickness relative to the ICE-5 G reconstruction, which is generally consistent with other recent studies that have focussed on Laurentide Ice Sheet history. The final model also features peak ice thicknesses of 1.2-1.3 km in the Baffin Island region, a modest reduction relative to ICE-5 G, and unchanged thicknesses for a region in the central Canadian Arctic Archipelago west of Baffin Island. Vertical land motion predictions of the final model fit observed crustal uplift rates well, after an adjustment is made for the elastic crustal response to present-day ice mass changes of regional ice cover. The new Laur16 model provides more than a factor of two improvement of the fit to the RSL data (χ2 measure of misfit) and a factor of nine improvement to the fit of the GPS data (mean squared error measure of fit), compared to the ICE-5 G starting model. Laur16 also fits the regional RSL data better by a factor of two and gives a slightly better fit to GPS uplift rates than the recent ICE-6 G model. The volume history of the Laur16 reconstruction corresponds to an up to 8 m reduction in global sea-level equivalent compared to ICE-5 G at LGM.

  16. Local Sea Level Derived from Reflected GNSS Signals

    NASA Astrophysics Data System (ADS)

    Löfgren, J. S.; Haas, R.; Scherneck, H.; Bos, M. S.

    2011-12-01

    The traditional way to observe sea level is to use tide gauges, resulting in measurements relative to the Earth's crust. However, in order to measure the sea-level change due to changes in ocean water volume and/or other oceanographic phenomena, all types of crustal motion at the measurement site need to be known. We present a remote sensing technique for measuring local sea level using standard geodetic-type Global Navigation Satellite System (GNSS) receivers. The installation consists of a zenith-looking Right Hand Circular Polarized (RHCP) antenna, receiving the direct signals, and a nadir-looking Left Hand Circular Polarized antenna, receiving the signals reflected of the sea surface. Each antenna is connected to a receiver and the antenna pair is deployed back-to-back at a coastal site. Estimating the vertical baseline between the two antennas, using standard geodetic analysis, the local sea level and its temporal variations can be determined. The advantage of this technique is that it allows to measure both sea surface height changes with relative positioning and land surface height changes, e.g., by precise point positioning of the RHCP antenna. Furthermore, the combined measurements of local sea level are automatically corrected for land motion, meaning that this installation could provide continuously reliable sea-level estimates in tectonic active regions. This GNSS-based tide gauge has been operating continuously at the Onsala Space Observatory (OSO) on the west coast of Sweden since September 2010. We present results from several months of operations and compare them to sea-level measurements from two stilling well gauges about 18 km south and 33 km north of OSO. We find a high degree of agreement between the time series with correlation coefficients of larger than 0.95. The root-mean-square differences between the GNSS-derived sea level and the stilling well gauge measurements are 5.9 cm and 5.5 cm, which is lower than between the two stilling well (6.1 cm). Furthermore, we present a tidal analysis of the three independent sea level time series and compare the derived tidal constituents among each other and with respect to theoretical models.

  17. An assessment of the genotoxic impact of the Sea Empress oil spill by the measurement of DNA adduct levels in selected invertebrate and vertebrate species.

    PubMed

    Harvey, J S; Lyons, B P; Page, T S; Stewart, C; Parry, J M

    1999-04-26

    The grounding of the Sea Empress oil tanker resulted in the release of 72,000 tonnes of crude oil into Milford Haven, Wales, UK. Our initial studies indicated that this contamination resulted in elevated levels of DNA adducts in one of the area's native marine species Lipophrys pholis [B.P. Lyons, J.S. Harvey, J.M. Parry, An initial assessment of the genotoxic impact of the Sea Empress oil spill by the measurement of DNA adduct levels in the intertidal teleost Lipophrys pholis, Mutat. Res. 390 (1997) 263-268]. These original studies were extended and the genotoxic impact of the oil contamination was investigated in the invertebrates Halichondria panicea and Mytilus edulis, along with the vertebrate fish species L. pholis, Pleuronectes platessa and Limanda limanda. DNA adduct levels were assessed in these species over a period of 2-17 months after the incident. The studies indicate differences in the impact of acute oil contamination upon vertebrate and invertebrate species. The oil contamination did not induce any detectable elevations in adduct levels in the invertebrate species H. panicea and M. edulis. In contrast, the oil contamination did appear to induce adducts in the vertebrate teleost species L. pholis, P. platessa and Lim. limanda. Despite some difficulties in sampling, the data obtained 12-17 months after the spill suggested that the affected species recovered from the oil contamination. While the studies indicate that the genetic impact of the oil contamination was less severe than might have been expected, it remains possible that the DNA adducts detected in the teleosts could lead to genetic changes in these species in the future. PMID:10224327

  18. Present-day sea level rise: A synthesis

    NASA Astrophysics Data System (ADS)

    Cazenave, Anny; Lombard, Alix; Llovel, William

    2008-11-01

    Measuring sea level change and understanding its causes have improved considerably in the recent years, essentially because new in situ and remote sensing data sets have become available. Here we report on the current knowledge of present-day sea level change. We briefly present observational results on sea level change from satellite altimetry since 1993 and tide gauges for the past century. We next discuss recent progress made in quantifying the processes causing sea level change on time scales ranging from years to decades, i.e., thermal expansion, land ice mass loss and land water storage change. For the 1993-2003 decade, the sum of climate-related contributions agree well (within the error bars) with the altimetry-based sea level, half of the observed rate of rise being due to ocean thermal expansion, land ice plus land waters explaining the other half. Since about 2003, thermal expansion increase has stopped, whereas the sea level continues to rise, although at a reduced rate compared to the previous decade (2.5 mm/yr versus 3.1 mm/yr). Recent increases in glacier melting and ice mass loss from the ice sheets appear able to account alone for the rise in sea level reported over the last five years.

  19. On the relationship between sea level and Spartina alterniflora production

    USGS Publications Warehouse

    Kirwan, Matthew L.; Christian, Robert R.; Blum, Linda K.; Brinson, Mark M.

    2012-01-01

    A positive relationship between interannual sea level and plant growth is thought to stabilize many coastal landforms responding to accelerating rates of sea level rise. Numerical models of delta growth, tidal channel network evolution, and ecosystem resilience incorporate a hump-shaped relationship between inundation and plant primary production, where vegetation growth increases with sea level up to an optimum water depth or inundation frequency. In contrast, we use decade-long measurements of Spartina alterniflora biomass in seven coastal Virginia (USA) marshes to demonstrate that interannual sea level is rarely a primary determinant of vegetation growth. Although we find tepid support for a hump-shaped relationship between aboveground production and inundation when marshes of different elevation are considered, our results suggest that marshes high in the intertidal zone and low in relief are unresponsive to sea level fluctuations. We suggest existing models are unable to capture the behavior of wetlands in these portions of the landscape, and may underestimate their vulnerability to sea level rise because sea level rise will not be accompanied by enhanced plant growth and resultant sediment accumulation.

  20. Lower bounds to future sea-level rise

    NASA Astrophysics Data System (ADS)

    Zecca, Antonio; Chiari, Luca

    2012-12-01

    Sea-level rise is among the most important changes expected as a consequence of anthropogenic global warming. Climate model-based projections made until the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) yield a 21st century rise spanning nearly 20-60 cm. However, it is known that current climate models are likely to underestimate sea-level change in response to rapid climatic variations. Recent alternative semi-empirical approaches predict a much higher sea-level rise than the IPCC AR4 projections. Nevertheless, the underway depletion of conventional fossil fuels might, at least in principle, constrain future fossil CO2 emissions and, in turn, affect also the extent of sea-level rise. Here we project 2000-2200 sea-level rise with a semi-empirical method coupled to a simple climate model that is run under a range of fossil-fuel exhaustion scenarios. We find that, in spite of fossil-fuel depletion, sea level is predicted to rise by at least ~ 80 cm at the end of this century and is expected to continue rising for at least the next two hundred years. The present results support the need for prompt and substantial emission cuts in order to slow down future sea-level rise and implement adaptation measures.

  1. Measuring sediment deposition and accretion on anthropogenic marshland - Part II: The adaptation capacity of the North Frisian Halligen to sea level rise

    NASA Astrophysics Data System (ADS)

    Schindler, Malte; Karius, Volker; Arns, Arne; Deicke, Matthias; von Eynatten, Hilmar

    2014-12-01

    Low coastlands, marshlands and islands all over the world are challenged by rising water levels due to climatic changes. The adaptation capacity of such lowlands is based on frequent inundations and according sedimentation processes. Exemplarily, a system of small islands west of Northern Germany was investigated over three years. At three out of ten so-called Halligen located in the Wadden Sea, the adaptation capacity of the anthropogenic marshland was determined. The Halligen Hooge, Langeness and Nordstrandischmoor have surface elevations only a few decimetres above mean high water and have to cope with an inundation frequency of nowadays up to 22 times per year. By use of methods introduced in Schindler et al. (2014, this volume) in combination with a 137Cs and 210Pb dating campaign on 12 sediment cores, vertical accretion rates were measured and detailed sediment accretion patterns presented. A good agreement was found between the used methods to calculate long term and short term marshland accretion rates. Sediment deposition and vertical marshland accretion is mainly controlled by the high tide events (single storm surges). Coastal protection structures, established in the early 20th century, decrease the inundation frequency and hinder the efficiency of the sediment transport by the tidal channel system on the Halligen. Vertical marshland accretion based on 210Pb dating for the time span 1915-2011 (1.0 ± 0.3 mm/a, Hooge, 1.2 ± 0.3 mm/a, Langeness and 2.6 ± 0.9 mm/a, Nordstrandischmoor) is in disequilibrium with the fast increasing mean high water level (MHW, 5.0 ± 0.3 mm/a). Projections until 2100 revealed that the extreme values (highest high waters, HHW) tend to rise much faster than the MHW or relative mean sea level (RMSL). Therefore an increasing hazard potential for the Halligen has to be expected if vertical marshland accretion does not accelerate in the future.

  2. Developing a Coastal Risk Indicator for Sea Level Rise

    NASA Astrophysics Data System (ADS)

    Masters, D. S.; Nerem, R.

    2012-12-01

    Coastal sea level rise is one the most important potential environmental risks. Multiple satellite altimeters flying on the same repeat orbit track have allowed estimation of global mean sea level for the past 20 years, and the time series has yielded information about the average rate of sea level increase over that time. Due to the duration, consistency, and inter-calibration of the altimeter measurements, the time series is now considered a climate record. The time series has also shown the strong dependence of sea level on interannual signals such as the ENSO and the NAO. But the most important sea level effects of climate change will be felt on the regional and local scales. At these smaller scales, local effects due to topography, tides, earth deformation (glacial isostatic adjustment (GIA), subsidence, etc.), and storm surges must also be considered when estimating the risks of sea level change to coastal communities. Recently, work has begun to understand the methods applicable to estimating the risks of expected sea level change to coastal communities (Strauss et al., 2012; Tebaldi et al., 2012). Tebaldi et al (2012) merged the expected global mean sea level increase from the semi-empirical model of Vermeer and Rahmstorf (2009) with historical local tide gauges to predict increases in storm surge risk posed by increasing sea level. In this work, we will further explore the currently available data and tools that can potentially be used to provide a sea level climate change indicator and local risk assessment along US coasts. These include global and regional sea level trends from the satellite altimetry climate record, in situ tide gauge measurements and the historical extremes at each location, local tide and storm surge models, topographic surveys of vulnerable coastlines, GIA models, and measurements of local subsidence and crustal deformation rates. We will also evaluate methods to estimate the increased risk to communities from sea level change coupled with storm surges and tides. Since large-scale ocean modes such the ENSO and NAO can have large temporary effects on local sea levels, we will also investigate whether the timing of these modes can be used in this risk assessment. The goal is to produce a climate indicator for use by planners, policy makers, and the general public, such as the National Climate Assessment, and as an ongoing effort to assess changing risks from expected sea level rise. References Strauss, B., R. Ziemlinski, J. Weiss, and J. Overpeck. "Tidally adjusted estimates of topographic vulnerability to sea level rise and flooding for the contiguous United States." Environmental Research Letters 7, no. 1 (2012). Tebaldi, C., B. Strauss, and C. Zervas. "Modelling sea level rise impacts on storm surges along US coasts." Environmental Research Letters 7, no. 1 (2012). Vermeer, M., and S. Rahmstorf. "Global sea level linked to global temperature." Proceedings of the National Academy of Sciences 106, no. 51 (2009): 21527-21532.

  3. Future sea-level rise in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Galassi, Gaia; Spada, Giorgio

    2014-05-01

    Secular sea level variations in the Mediterranean Sea are the result of a number of processes characterized by distinct time scales and spatial patterns. Here we predict the future sea level variations in the Mediterranean Sea to year 2050 combining the contributions from terrestrial ice melt (TIM), glacial isostatic adjustment (GIA), and the ocean response (OR) that includes the thermal expansion and the ocean circulation contributions. The three contributions are characterized by comparable magnitudes but distinctly different sea-level fingerprints across the Mediterranean basin. The TIM component of future sea-level rise is taken from Spada et al. (2013) and it is mainly driven by the melt of small glaciers and ice caps and by the dynamic ice loss from Antarctica. The sea-level fingerprint associated with GIA is studied using two distinct models available from the literature: ICE-5G(VM2) (Peltier, 2004) and the ice model progressively developed at the Research School of Earth Sciences (RSES) of the National Australian University (KL05) (see Fleming and Lambeck, 2004 and references therein). Both the GIA and the TIM sea-level predictions have been obtained with the aid of the SELEN program (Spada and Stocchi, 2007). The spatially-averaged OR component, which includes thermosteric and halosteric sea-level variations, recently obtained using a regional coupled ocean-atmosphere model (Carillo et al., 2012), vary between 2 and 7 cm according to scenarios adopted (EA1B and EA1B2, see Meehl at al., 2007). Since the sea-level variations associated with TIM mainly result from the gravitational interactions between the cryosphere components, the oceans and the solid Earth, and long-wavelength rotational variations, they are characterized by a very smooth global pattern and by a marked zonal symmetry reflecting the dipole geometry of the ice sources. Since the Mediterranean Sea is located in the intermediate far-field of major ice sources, TIM sea-level changes have sub-eustatic values (i.e. they do not exceed the global average) and show little (but still significant) variations across the basin associated with the subsidence driven by the meltwater load. For year 2050, TIM calculations predict a sea-level rise of ~10 and ~30 cm for the mid range and the high end scenarios, respectively. Mainly because of the distinct mantle viscosity profiles adopted in ICE-5G(VM2) and KL05, the GIA patterns differ significantly and, in contrast with the TIM fingerprint, are both characterized by strong variations across the Mediterranean Sea, showing maximum values in the bulk of the basin. For the OR component, a significant geographical variation is observed across the Mediterranean sub-basins, corresponding to different Atlantic boundary conditionsAccording to this study, the total future sea-level rise for year 2050 will reach maximum values for the extreme scenario (hig-hend prediction for TIM, KL05 for GIA and EA1B2 for OR) of ˜ 27 cm in average with peak of ˜ 30 cm in the central sub-basins. Our results show that when these three components of future sea-level rise are simultaneously considered, the spatial variability is enhanced because of the neatly distinct geometry of the three fingerprints. References: Carillo, A., Sannino, G., Artale, V., Ruti, P., Calmanti, S., DellAquila, A., 2012, Clim. Dyn. 39 (9-10), 2167-2184; Fleming, K. and Lambeck, K., 2004, Quat. Sci. Rev. 23 (9-10), 1053-1077; Meehl, G.A., and 11 others, 2007, in Climate Change 2007: The Physical Science Basis, Cambridge University Press; Peltier W.R., 2004, Annu. Rev. Earth Pl. Sc., 32, 111-149; Spada, G. and Stocchi, P., 2007, Comput. and Geosci., 33(4), 538-562; Spada G., Bamber J. L., Hurkmans R. T. W. L., 2013, Geophys. Res. Lett., 1-5, 40.

  4. Overestimation of marsh vulnerability to sea level rise

    USGS Publications Warehouse

    Kirwan, Matthew L.; Temmerman, Stijn; Skeehan, Emily E.; Guntenspergen, Glenn R.; Fagherazzi, Sergio

    2016-01-01

    Coastal marshes are considered to be among the most valuable and vulnerable ecosystems on Earth, where the imminent loss of ecosystem services is a feared consequence of sea level rise. However, we show with a meta-analysis that global measurements of marsh elevation change indicate that marshes are generally building at rates similar to or exceeding historical sea level rise, and that process-based models predict survival under a wide range of future sea level scenarios. We argue that marsh vulnerability tends to be overstated because assessment methods often fail to consider biophysical feedback processes known to accelerate soil building with sea level rise, and the potential for marshes to migrate inland.

  5. Overestimation of marsh vulnerability to sea level rise

    NASA Astrophysics Data System (ADS)

    Kirwan, Matthew L.; Temmerman, Stijn; Skeehan, Emily E.; Guntenspergen, Glenn R.; Fagherazzi, Sergio

    2016-03-01

    Coastal marshes are considered to be among the most valuable and vulnerable ecosystems on Earth, where the imminent loss of ecosystem services is a feared consequence of sea level rise. However, we show with a meta-analysis that global measurements of marsh elevation change indicate that marshes are generally building at rates similar to or exceeding historical sea level rise, and that process-based models predict survival under a wide range of future sea level scenarios. We argue that marsh vulnerability tends to be overstated because assessment methods often fail to consider biophysical feedback processes known to accelerate soil building with sea level rise, and the potential for marshes to migrate inland.

  6. Obstacles to adaptation decisions in the developing world: A case study of coastal protection measures and sea-level rise in Kiribati

    NASA Astrophysics Data System (ADS)

    Donner, S. D.; Webber, S.

    2014-12-01

    International aid is increasingly focused on adaptation to climate change. At recent meetings of the parties to the United Nations Framework Convention on Climate Change, the developed world agreed to rapidly increase international assistance to help the developing world respond to the impacts of climate change. Here, we examine the decision-making challenges facing internationally supported climate change adaptation projects given the large uncertainty in future climate predictions, using the example of efforts to implement coastal protection measures (e.g. sea walls, mangrove planting) in Kiribati. The central equatorial Pacific country is home to the Kiribati Adaptation Project, the first national-level climate change adaptation project supported by the World Bank. Drawing on interview and document research conducted over an 8-year period, we trace the forces influencing decisions about coastal protection measures, starting from the variability and uncertainty in climate change projections, through the trade-offs between different measures, to the social, political, and economic context in which decisions are finally made. We then discuss how sub-optimal adaptation measures may be implemented despite years of planning, consultation, and technical studies. This qualitative analysis of the real-world process of climate change adaptation reveals that embracing a culturally appropriate and short-term (~20 years) planning horizon, while not ignoring the longer-term future, may reduce the influence of scientific uncertainty on decisions and provide opportunities to learn from mistakes, reassess the science, and adjust suboptimal investments.

  7. Understanding Sea Level Rise and Variability

    NASA Astrophysics Data System (ADS)

    Church, John; Wilson, Stan; Woodworth, Philip; Aarup, Thorkild

    2007-01-01

    The coastal zone changed considerably during the twentieth century due to growing populations and increasing urbanization. A recent study indicated that in 1990, 23% of the world's population (1.2 billion people) were living within both a 100-kilometer distance and a 100-meter elevation of the coast at densities 3 times higher than the global average. Society is becoming increasingly vulnerable to sea level extremes, as Hurricane Katrina demonstrated. Rising levels will result in more flooding, even if storm intensities do not increase. Improved understanding of the reasons for sea level rise and variability is required to reduce the uncertainties in sea level rise projections, and this improved understanding could contribute to more effective coastal planning and management.

  8. Analysis of the sea levels in Kiribati A Rising Sea of Misrepresentation Sinks Kiribati

    NASA Astrophysics Data System (ADS)

    Parker, Albert

    2016-03-01

    The sea levels of Kiribati have been stable over the last few decades, as elsewhere in the world. The Australian government funded Pacific Sea Level Monitoring (PSLM) project has adjusted sea level records to produce an unrealistic rising trend. Some information has been hidden or neglected, especially from sources of different management. The measured monthly average mean sea levels suffer from subsidence or manipulation resulting in a tilting from the about 0 (zero) mm/year of nearby tide gauges to 4 (four) mm/year over the same short time window. Real environmental problems are driven by the increasing local population leading to troubles including scarcity of water, localized sinking and localised erosion.

  9. Visualizing Sea Level Rise with Augmented Reality

    NASA Astrophysics Data System (ADS)

    Kintisch, E. S.

    2013-12-01

    Looking Glass is an application on the iPhone that visualizes in 3-D future scenarios of sea level rise, overlaid on live camera imagery in situ. Using a technology known as augmented reality, the app allows a layperson user to explore various scenarios of sea level rise using a visual interface. Then the user can see, in an immersive, dynamic way, how those scenarios would affect a real place. The first part of the experience activates users' cognitive, quantitative thinking process, teaching them how global sea level rise, tides and storm surge contribute to flooding; the second allows an emotional response to a striking visual depiction of possible future catastrophe. This project represents a partnership between a science journalist, MIT, and the Rhode Island School of Design, and the talk will touch on lessons this projects provides on structuring and executing such multidisciplinary efforts on future design projects.

  10. Sea Level Rise in Santa Clara County

    NASA Technical Reports Server (NTRS)

    Milesi, Cristina

    2005-01-01

    Presentation by Cristina Milesi, First Author, NASA Ames Research Center, Moffett Field, CA at the "Meeting the Challenge of Sea Level Rise in Santa Clara County" on June 19, 2005 Santa Clara County, bordering with the southern portion of the San Francisco Bay, is highly vulnerable to flooding and to sea level rise (SLR). In this presentation, the latest sea level rise projections for the San Francisco Bay will be discussed in the context of extreme water height frequency and extent of flooding vulnerability. I will also present preliminary estimations of levee requirements and possible mitigation through tidal restoration of existing salt ponds. The examples will draw mainly from the work done by the NASA Climate Adaptation Science Investigators at NASA Ames.

  11. Climate And Sea Level: It's In Our Hands Now

    NASA Astrophysics Data System (ADS)

    Turrin, M.; Bell, R. E.; Ryan, W. B. F.

    2014-12-01

    Changes in sea level are measurable on both a local and a global scale providing an accessible way to connect climate to education, yet engaging teachers and students with the complex science that is behind the change in sea level can be a challenge. Deciding how much should be included and just how it should be introduced in any single classroom subject area can be an obstacle for a teacher. The Sea Level Rise Polar Explorer App developed through the PoLAR CCEP grant offers a guided tour through the many layers of science that impact sea level rise. This map-based data-rich app is framed around a series of questions that move the user through map layers with just the level of complexity they chose to explore. For a quick look teachers and students can review a 3 or 4 sentence introduction on how the given map links to sea level and then launch straight into the interactive touchable map. For a little more in depth look they can listen to (or read) a one-minute recorded background on the data displayed in the map prior to launching in. For those who want more in depth understanding they can click to a one page background piece on the topic with links to further visualizations, videos and data. Regardless of the level of complexity selected each map is composed of clickable data allowing the user to fully explore the science. The different options for diving in allow teachers to differentiate the learning for either the subject being taught or the user level of the student group. The map layers also include a range of complexities. Basic questions like "What is sea level?" talk about shorelines, past sea levels and elevations beneath the sea. Questions like "Why does sea level change?" includes slightly more complex issues like the role of ocean temperature, and how that differs from ocean heat content. And what is the role of the warming atmosphere in sea level change? Questions about "What about sea level in the past?" can bring challenges for students who have difficulty with time scales, but sections on "Who is Vulnerable?" are very tangible to the students as they look at maps of population density, ocean island populations in danger of submersion, and what regions are most vulnerable to flooding. Teachers and students alike can explore a wealth of authentic science data in an engaging and accessible way.

  12. Antarctic mass balance and sea level change

    NASA Astrophysics Data System (ADS)

    Bentley, Charles R.

    The Antarctic ice, remote as it is, has the potential to affect coastal communities and habitats around the world, because any change in its mass will directly affect mean sea level. Despite all the study of the ice sheet in the last several decades, however, it is still uncertain whether the ice sheet is growing, shrinking, or unchanging in mass. The most recent studies are contradictory—glaciological evidence from the continent suggests that the ice sheet is slowly growing, oceanographic evidence around the continent suggests that it is shrinking, and indirect satellite evidence relating to changes in mass distribution over the surface of the globe suggests that changes of either sign must be small.The glaciological evidence has most recently been summarized by Bentley and Giovinetto [1991]. By analyzing all available measurements on the rate of snow accumulation on the ice sheet (the mass input) and the mass flux across the boundary between the land-based and floating margins of the ice sheet (the mass output), they came to the conclusion that there is a net gain of about 200 Gt yr-1, that is, a sea-level lowering of about 0.5 mm yr-1. The data cover the large drainage systems that encompass the vast interior plateaus where the mass input rates are small. Much less is known about more limited coastal systems characterized by higher specific mass input rates. Nevertheless, it seems unlikely that these smaller regions could be losing mass rapidly enough to make up for the mass gain over the majority of the continent.

  13. Twentieth century sea level: an enigma.

    PubMed

    Munk, Walter

    2002-05-14

    Changes in sea level (relative to the moving crust) are associated with changes in ocean volume (mostly thermal expansion) and in ocean mass (melting and continental storage): zeta(t) = zeta(steric)(t) + zeta(eustatic)(t). Recent compilations of global ocean temperatures by Levitus and coworkers are in accord with coupled ocean/atmosphere modeling of greenhouse warming; they yield an increase in 20th century ocean heat content by 2 x 10(23) J (compared to 0.1 x 10(23) J of atmospheric storage), which corresponds to zeta(greenhouse)(2000) = 3 cm. The greenhouse-related rate is accelerating, with a present value zeta(greenhouse)(2000) approximately 6 cm/century. Tide records going back to the 19th century show no measurable acceleration throughout the late 19th and first half of the 20th century; we take zeta(historic) = 18 cm/century. The Intergovernmental Panel on Climate Change attributes about 6 cm/century to melting and other eustatic processes, leaving a residual of 12 cm of 20th century rise to be accounted for. The Levitus compilation has virtually foreclosed the attribution of the residual rise to ocean warming (notwithstanding our ignorance of the abyssal and Southern Oceans): the historic rise started too early, has too linear a trend, and is too large. Melting of polar ice sheets at the upper limit of the Intergovernmental Panel on Climate Change estimates could close the gap, but severe limits are imposed by the observed perturbations in Earth rotation. Among possible resolutions of the enigma are: a substantial reduction from traditional estimates (including ours) of 1.5-2 mm/y global sea level rise; a substantial increase in the estimates of 20th century ocean heat storage; and a substantial change in the interpretation of the astronomic record. PMID:12011419

  14. Twentieth century sea level: An enigma

    PubMed Central

    Munk, Walter

    2002-01-01

    Changes in sea level (relative to the moving crust) are associated with changes in ocean volume (mostly thermal expansion) and in ocean mass (melting and continental storage): ζ(t) = ζsteric(t) + ζeustatic(t). Recent compilations of global ocean temperatures by Levitus and coworkers are in accord with coupled ocean/atmosphere modeling of greenhouse warming; they yield an increase in 20th century ocean heat content by 2 × 1023 J (compared to 0.1 × 1023 J of atmospheric storage), which corresponds to ζgreenhouse(2000) = 3 cm. The greenhouse-related rate is accelerating, with a present value ζ̇greenhouse(2000) ≈ 6 cm/century. Tide records going back to the 19th century show no measurable acceleration throughout the late 19th and first half of the 20th century; we take ζ̇historic = 18 cm/century. The Intergovernmental Panel on Climate Change attributes about 6 cm/century to melting and other eustatic processes, leaving a residual of 12 cm of 20th century rise to be accounted for. The Levitus compilation has virtually foreclosed the attribution of the residual rise to ocean warming (notwithstanding our ignorance of the abyssal and Southern Oceans): the historic rise started too early, has too linear a trend, and is too large. Melting of polar ice sheets at the upper limit of the Intergovernmental Panel on Climate Change estimates could close the gap, but severe limits are imposed by the observed perturbations in Earth rotation. Among possible resolutions of the enigma are: a substantial reduction from traditional estimates (including ours) of 1.5–2 mm/y global sea level rise; a substantial increase in the estimates of 20th century ocean heat storage; and a substantial change in the interpretation of the astronomic record. PMID:12011419

  15. Sea level change. Inherited landscapes and sea level change.

    PubMed

    Cloetingh, Sierd; Haq, Bilal U

    2015-01-23

    Enabled by recently gained understanding of deep-seated and surficial Earth processes, a convergence of views between geophysics and sedimentary geology has been quietly taking place over the past several decades. Surface topography resulting from lithospheric memory, retained at various temporal and spatial scales, has become the connective link between these two methodologically diverse geoscience disciplines. Ideas leading to the hypothesis of plate tectonics originated largely with an oceanic focus, where dynamic and mostly horizontal movements of the crust could be envisioned. But when these notions were applied to the landscapes of the supposedly rigid plate interiors, there was less success in explaining the observed anomalies in terrestrial topography. Solid-Earth geophysics has now reached a developmental stage where vertical movements can be measured and modeled at meaningful scales and the deep-seated structures can be imaged with increasing resolution. Concurrently, there have been advances in quantifying mechanical properties of the lithosphere (the solid outer skin of Earth, usually defined to include both the crust and the solid but elastic upper mantle above the asthenosphere). The lithosphere acts as the intermediary that transfers the effects of mantle dynamics to the surface. These developments have allowed us to better understand the previously puzzling topographic features of plate interiors and continental margins. On the sedimentary geology side, new quantitative modeling techniques and holistic approaches to integrating source-to-sink sedimentary systems have led to clearer understanding of basin evolution and sediment budgets that allow the reconstruction of missing sedimentary records and past geological landscapes. PMID:25613899

  16. The Sea Level Fingerprints of Global Change

    NASA Astrophysics Data System (ADS)

    Mitrovica, J. X.; Hay, C.; Kopp, R. E., III; Morrow, E.

    2014-12-01

    It may be difficult to persuade those living in northern Europe that the sea level changes that their coastal communities face depends less on the total melting of polar ice sheets and glaciers than on the individual contributions to this total. In particular, melting of a specific ice sheet or mountain glacier drives deformational, gravitational and rotational perturbations to the Earth system that are manifest in a unique geometry, or fingerprint, of global sea level change. For example, melting from the Greenland Ice Sheet equivalent to 1 mm/yr of global mean sea level (GMSL) rise will lead to sea level rise of ~0 mm/yr in Dublin, ~0.2 mm/yr in Amsterdam, ~0.4 mm/yr in Boston and ~1.2 mm/yr in Cape Town. In contrast, if the same volume of ice melted from the West Antarctic Ice Sheet, all of the above sites would experience a sea level rise in the range 1.1-1.2 mm/yr. These fingerprints of modern ice melting, together with ocean thermal expansion and dynamic effects, and the ongoing signal from glacial isostatic adjustment in response to the last ice age, combine to produce a sea level field with significant geographic variability. In this talk I will highlight an analysis of global tide gauge records that takes full advantage of this variability to estimate both GMSL and the sources of meltwater over the last century, and to project GMSL to the end of the current century.

  17. The Enigma of 20th century sea level change

    NASA Astrophysics Data System (ADS)

    Cathles, Larry

    2014-05-01

    Sea level has been constant at near-present levels from ~5500 calendar years BP to the end of the Little Ice Age at ~1860 AD. Since ~1900, tide gauge measurements indicate that it has risen steadily at ~2 mm/yr by about 18 cm. The comparative stability of sealevel from 5500 cal yr BP to 1860 AD is robust, being suggested by near-shore Mediterranean archeological sites, the few sea level records that extend back to 1700 AD, and the impossibility of projecting the current sea level rise of ~2 mm/y back 5000 years (it would produce a global 10 m inundation, which is not observed) (Douglas et al., 2001, Academic Press). The post 1870 sea level rise is not due to heating of the upper ocean (Liviticus et al., 2000, Science). Munk (2002, PNAS) characterized it as an "enigma", dismissing an upper ocean steric sea level explanation as "too little" (~3 cm), "too late" (the rise started in 1860), and "too linear" (not accelerating with the accelerating CO2 increase). GRACE gravity measurements show a near zero change in ocean mass. Cazenave et al. (2009, Global and Planetary Change) indicate a slight decrease in ocean mass between 2003 and 2008. The rate of meltwater mass being added to the oceans essentially equals the GIA correction (Chambers et al., 2010, JGR). Different GIA models give ocean mass increase ranging from 0.5 to 2 mm/y of equivalent sea level rise. Our GIA model suggests no ocean mass increases (~0 mm/y of equivalent sea level rise). In this talk I show that the heating of a two layer ocean model driven by the temperature changes that have occurred over the last 1000 years since the peak of the Medieval Warm Period produces a ~2mm/yr linear sea level rise over the last 100 years with much smaller preceding sea level changes. Ocean mass could be unchanging over the last century as well as the last ~5000 years. This result is compatible with GRACE measurements and eclipse data constraints, predictions of our GIA model, and it resolves the enigma the 20th Century sea level change noted by Munk.

  18. Measuring the sea quark polarization

    SciTech Connect

    Makdisi, Y.; RHIC Spin Collaboration

    1993-06-01

    Spin is a fundamental degree of freedom and measuring the spin structure functions of the nucleon should be a basic endeavor for hadron physics. Polarization experiments have been the domain of fixed target experiments. Over the years large transverse asymmetries have been observed where the prevailing QCD theories predicted little or no asymmetries, and conversely the latest deep inelastic scattering experiments of polarized leptons from polarized targets point to the possibility that little of the nucleon spin is carried by the valence quarks. The possibility of colliding high luminosity polarized proton beams in the Brookhaven Relativistic Heavy Ion Collider (RHIC) provides a great opportunity to extend these studies and systematically probe the spin dependent parton distributions specially to those reactions that are inaccessible to current experiments. This presentation focuses on the measurement of sea quark and possibly the strange quark polarization utilizing the approved RHIC detectors.

  19. Measuring the sea quark polarization

    SciTech Connect

    Makdisi, Y.

    1993-01-01

    Spin is a fundamental degree of freedom and measuring the spin structure functions of the nucleon should be a basic endeavor for hadron physics. Polarization experiments have been the domain of fixed target experiments. Over the years large transverse asymmetries have been observed where the prevailing QCD theories predicted little or no asymmetries, and conversely the latest deep inelastic scattering experiments of polarized leptons from polarized targets point to the possibility that little of the nucleon spin is carried by the valence quarks. The possibility of colliding high luminosity polarized proton beams in the Brookhaven Relativistic Heavy Ion Collider (RHIC) provides a great opportunity to extend these studies and systematically probe the spin dependent parton distributions specially to those reactions that are inaccessible to current experiments. This presentation focuses on the measurement of sea quark and possibly the strange quark polarization utilizing the approved RHIC detectors.

  20. North Atlantic sea-level variability during the last millennium

    NASA Astrophysics Data System (ADS)

    Gehrels, Roland; Long, Antony; Saher, Margot; Barlow, Natasha; Blaauw, Maarten; Haigh, Ivan; Woodworth, Philip

    2014-05-01

    Climate modelling studies have demonstrated that spatial and temporal sea-level variability observed in North Atlantic tide-gauge records is controlled by a complex array of processes, including ice-ocean mass exchange, freshwater forcing, steric changes, changes in wind fields, and variations in the speed of the Gulf Stream. Longer records of sea-level change, also covering the pre-industrial period, are important as a 'natural' and long-term baseline against which to test model performance and to place recent and future sea-level changes and ice-sheet change into a long-term context. Such records can only be reliably and continuously reconstructed from proxy methods. Salt marshes are capable of recording decimetre-scale sea-level variations with high precision and accuracy. In this paper we present four new high-resolution proxy records of (sub-) decadal sea-level variability reconstructed from salt-marsh sediments in Iceland, Nova Scotia, Maine and Connecticut that span the past 400 to 900 years. Our records, based on more than 100 new radiocarbon analyses, Pb-210 and Cs-137 measurements as well as other biological and geochemical age markers, together with hundreds of new microfossil observations from contemporary and fossil salt marshes, capture not only the rapid 20th century sea-level rise, but also small-scale (decimetre, multi-decadal) sea-level fluctuations during preceding centuries. We show that in Iceland three periods of rapid sea-level rise are synchronous with the three largest positive shifts of the reconstructed North Atlantic Oscillation (NAO) index. Along the North American east coast we compare our data with salt-marsh records from New Jersey, North Carolina and Florida and observe a trend of increased pre-industrial sea-level variability from south to north (Florida to Nova Scotia). Mass changes and freshwater forcing cannot explain this pattern. Based on comparisons with instrumental sea-level data and modelling studies we hypothesise that multi-decadal to centennial changes in wind and air pressure are more important than mass flux from land-based ice as drivers of North Atlantic sea-level variability during the last millennium.

  1. Two centuries of mean Baltic Sea level variability - an overview

    NASA Astrophysics Data System (ADS)

    Hünicke, Birgit; Zorita, Eduardo; Madsen, Kristine S.; Johannson, Milla

    2015-04-01

    The understanding of the processes which drive future climatic trends of sea-level on global to regional scales presumes the understanding of long-term variability in the observational period. This requires an accurate assessment of past and recent global and regional sea-level changes. Here, we review the observed changes (1800-2000) in mean sea-level variability in the Baltic region and the main (climate) drivers for these changes. We introduce the datasets available for studying sea-level and review the major published findings which can be derived from them. The Baltic is one of the most investigated sea-level sites in the world. It has a remarkable number of long and high quality densely spaced, tide gauge records with many stations in continuous operation since the late 19th century and some of the oldest sea-level records reporting since 200 years. More than 45 stations with at least 60 years of data have continued until recent times. Mean Baltic Sea level changes are dominated by crustal deformations due to the glacio-isostatic land movement effect. The basin-wide pattern of relative sea-level trends shows a clear north-south gradient with a negative rate of -8.2 mm/yr in the Gulf of Bothnia. Thus, RSL is falling in the northern Baltic (where the continental crust is uplifting at roughly 10 mm/yr) and rising in parts of the Southern Baltic. Baltic Sea level changes are affected by a sum of processes. These include thermo and halosteric effects, changes in wind, surface air-pressure and ocean currents, increasing freshwater input and gravitational effects. The decadal sea-level variability around the quasi-linear long-term trend is strongly influenced by westerly winds, closely related to the dominant large-scale sea-level pressure (SLP) pattern of the North Atlantic (NAO). The correlation between sea-level and SLP is highest in winter, but shows significant temporal and spatial heterogeneity with low values in southern Baltic parts. The decadal influence of other atmospheric forcing factors is found to vary geographically. The annual cycle in Baltic sea-level displays, in general, higher values during winter and lower values during spring with an increase in the amplitude (winter-spring sea-level trend) 1800-2000. The magnitude of these increasing trends is found to be basin-wide uniform (except for the Skagerrak area). The precise mechanisms responsible for this have not been completely ascertained, but are very likely not exclusively of regional to local origin (e.g. due to wind-driven changes). Baltic absolute sea-level estimated from recent combined analysis of geodetic information (measurements and models) and tide gauge observations, show positive trends in the range of 1.3 to 1.8 mm/yr, depending on the spatial and temporal coverage of the considered datasets (1800-2000). These values lie within the range of recent estimates of global trends. Recent changes in linear (30yr) gliding trends of Baltic tide-gauge records (1800-2000) show generally increasing trends, but similar or even slightly higher than recent 30-year rates were observed around 1900 and 1950. All sites show a slight acceleration of the sea-level rate, but the large decadal variability around these positive trends hampers to establish its local statistical significance.

  2. Improvements of sea level anomaly maps in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Cheng, Yongcun; Baltazar Andersen, Ole; Knudsen, Per

    2013-04-01

    Obtaining satellite data at high latitude regions is generally very problematic. In the Arctic Ocean (For this investigation defined as 65°N-82°N), the ERS and ENVISAT sun-synchronous satellite altimetry measurements are nearly always affected by the presence of sea ice. Consequently, it is difficult to get accurate altimetric data for oceanography and climatology and this affect i.e., determination of the linear sea level trend over the regions. The objective of our study is to develop a new 3 days sea level anomaly maps in the Arctic Ocean. Multi-satellite (i.e., ERS-1, ERS-2 and ENVISAT) along track sea level anomaly data is extracted by applying adjusted editing criteria. Initially, the removal of orbit errors in sun-synchronous satellite altimetry is performed. A joint crossover with simultaneous TOPEX/Jason satellite altimetry, are used to adjust the long wavelength bias and tilt of the ERS-1, ERS-2 and ENVISAT. Subsequently, the adjusted sea level anomalies are gridded to a normal 0.5°×0.5°grid using collocation with a second-order Markov covariance function using spatial temporal interpolation which takes into account data from nearby periods in case of missing data. The data is then combined with tide gauge data and model outputs, the new data is used to study the sea level variability in Arctic Ocean. The contributors (for example, thermosteric, ice sheets and water mass) to the sea level change in the region are investigated. Moreover, significant decadal signal in sea level variation is found from tide gauge data and its comparison with AO index. The presentation is a contribution to the EU 7th FW supported projects MONARCH-A.

  3. Experiments in Reconstructing Twentieth-Century Sea Levels

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Douglas, Bruce C.

    2011-01-01

    One approach to reconstructing historical sea level from the relatively sparse tide-gauge network is to employ Empirical Orthogonal Functions (EOFs) as interpolatory spatial basis functions. The EOFs are determined from independent global data, generally sea-surface heights from either satellite altimetry or a numerical ocean model. The problem is revisited here for sea level since 1900. A new approach to handling the tide-gauge datum problem by direct solution offers possible advantages over the method of integrating sea-level differences, with the potential of eventually adjusting datums into the global terrestrial reference frame. The resulting time series of global mean sea levels appears fairly insensitive to the adopted set of EOFs. In contrast, charts of regional sea level anomalies and trends are very sensitive to the adopted set of EOFs, especially for the sparser network of gauges in the early 20th century. The reconstructions appear especially suspect before 1950 in the tropical Pacific. While this limits some applications of the sea-level reconstructions, the sensitivity does appear adequately captured by formal uncertainties. All our solutions show regional trends over the past five decades to be fairly uniform throughout the global ocean, in contrast to trends observed over the shorter altimeter era. Consistent with several previous estimates, the global sea-level rise since 1900 is 1.70 +/- 0.26 mm/yr. The global trend since 1995 exceeds 3 mm/yr which is consistent with altimeter measurements, but this large trend was possibly also reached between 1935 and 1950.

  4. Sea-Level Anomalies Facilitate Beach Erosion and Increase Barrier Island Vulnerability to Storms and Sea-Level Rise

    NASA Astrophysics Data System (ADS)

    Theuerkauf, E. J.; Rodriguez, A. B.; Fegley, S. R.; Luettich, R. A., Jr.

    2014-12-01

    Sea-level anomalies are intra-seasonal (weeks to months) periods of high water level induced by oceanographic and meteorological processes, such as reduced Gulf Stream transport strength or persistent northeasterly winds. Although flooding associated with sea-level anomalies has been documented along continental coastlines (e.g. U.S. East Coast), these phenomena are not presently included in coastal models and management plans. We present the first measurements of beach erosion after a year with frequent sea-level anomalies. Erosion during this year, which was not impacted by large storms, was similar to a year with a hurricane, indicating that sea-level anomalies are important facilitators of coastal erosion. Beach erosion was measured at Onslow Beach, NC (OB) in a year with frequent sea-level anomalies (2009-2010) and compared to erosion during a year with no major events (2010-2011) and the year with Hurricane Irene (2011-2012). Sea-level anomalies were identified in water level data from a NOAA tide gauge in Wrightsville Beach, NC. From 2009-2010 anomalously high sea level occurred ~40% of the time, compared to ~8% from 2010-2011 and ~10% from 2011-2012. Significant wave heights, measured from an acoustic wave and current profiler and NOAA buoys offshore of OB, were not statistically different among these 3 years. The average backshore, high intertidal, and mid intertidal maximum depth of erosion for all sites along OB in the year with frequent sea-level anomalies were ~25, 50, and 55 cm, respectively. These values are greater than those measured after the year with no major events (~13, 29, and 32 cm) and similar to those measured after the year with Hurricane Irene (~27, 49, and 40 cm). OB has high along-strike variability in barrier island morphology, thus results apply to many beaches and barrier islands. Our results suggest that anomalies are important mechanisms of coastal change and likely amplify erosion in response to accelerated sea-level rise and changes in storm frequency and intensity.

  5. Detailed Tropical Sea Level Record Spanning the Younger Dryas Chronozone

    NASA Astrophysics Data System (ADS)

    Abdul, N. A.; Mortlock, R. A.; Wright, J. D.; Fairbanks, R. G.

    2010-12-01

    Variability in sea level is a fundamental measure of past changes in continental ice volume and provides an important benchmark to test climate change hypotheses. Records of the most recent deglaciation show two pulses of accelerated sea-level rise (Meltwater Pulses 1A and 1B) separated by an interval of slower sea level rise. The Younger Dryas chronozone falls within the interval between MWP 1A and 1B. It was first described over 100 years ago and remains one of the most studied periods in Earth’s history. The Younger Dryas was originally constrained with 14C dating to the interval between 11,000 and 10,000 14C years BP, which converts to 13,000 to 11,640 calendar years BP. The climatic expression of the Younger Dryas was most pronounced in the circum North Atlantic where climate proxies returned in some regions to near glacial values. Interpretations of the Younger Dryas’ significance range from a catastrophic global cooling event accompanied by Northern hemisphere ice sheet growth to simply regional changes in ocean and air mass mixing zones confined mainly to the North Atlantic. A detailed sea level record containing the interval from the end of MWP 1A to the beginning of MWP 1B (~14,000 to 11,300 years BP) was generated using 26 new U/Th dates from our 2007 Barbados offshore drilling expedition combined with our 1988 expedition measurements. 16 of these dates fall within the Younger Dryas Chronozone. Younger Dryas sea level positions were based on Acropora palmata samples from 3 overlapping and contemporaneous offshore drill cores (RGF 12 and BBDS 9 & 10) and corrected for minor tectonic uplift. From 14,000 to 11,300 years BP, sea level rose from ~81 to 56.5 m below present sea level with an initial rate of 10 m/kyr that decreased smoothly to <5 m/kyr at the base of MWP 1B. At the beginning of the Younger Dryas, sea level was at 69 m below present and rose 8 m by the end of this interval. In the context of the Barbados sea level record, the Younger Dryas interval recorded only a minor slowing of sea level rise and is a continuation of the trend that began at the top of MWP 1A and ended with MWP 1B.

  6. Sea Grant Education at the University Level.

    ERIC Educational Resources Information Center

    Fiske, Shirley J.

    1998-01-01

    Sea Grant's investment in university-level education shows a diversity of avenues for supporting students from experience-based internships, merit scholarships, and fellowships to team-based multidisciplinary undergraduate education. Describes such programs as Undergraduate Research Opportunities in ocean engineering, graduate research

  7. Sea Level Rise Coastal Property Model

    EPA Science Inventory

    The impact of sea level rise on coastal properties depends critically on the human response to the threat, which in turn depends on several factors, including the immediacy of the risk, the magnitude of property value at risk, options for adapting to the threat and the cost of th...

  8. Sea Level Rise National Coastal Property Model

    EPA Science Inventory

    The impact of sea level rise on coastal properties depends critically on the human response to the threat, which in turn depends on several factors, including the immediacy of the risk, the magnitude of property value at risk, options for adapting to the threat and the cost of th...

  9. Sea Grant Education at the University Level.

    ERIC Educational Resources Information Center

    Fiske, Shirley J.

    1998-01-01

    Sea Grant's investment in university-level education shows a diversity of avenues for supporting students from experience-based internships, merit scholarships, and fellowships to team-based multidisciplinary undergraduate education. Describes such programs as Undergraduate Research Opportunities in ocean engineering, graduate research…

  10. The Influence of Wind and Basin Eddies in Controlling Sea Level Variations in the Coastal Red Sea

    NASA Astrophysics Data System (ADS)

    Abualnaja, Yasser O.; Churchill, James H.; Nellayaputhenpeedika, Mohammedali; Limeburner, Richard

    2015-04-01

    Sea level variations in the central Red Sea coastal zone span a range of roughly 1.2 m. Though relatively small, these water level changes can significantly impact the environment over the shallow reef tops prevalent in the central Red Sea, altering the water depth by a factor or two or more. Roughly half of the coastal sea level variance in central Red Sea is due to elevation changes in an 'intermediate' frequency band, with periods between 2 days and 1 month. We examined the sea level signal in this band using the data from pressure sensors maintained for more than five years at a number of locations in Saudi Arabian coastal waters between 20.1 and 23.5 oN. We find that the intermediate-band sea level variations are strongly correlated with the local wind stress measured at a meteorological buoy. The maximum pressure-wind correlation occurs at wind direction closely aligned with the alongshore orientation and at a lag (wind leading) of 45 hr, which is consistent with the expected response of the coastal sea level to local wind forcing. However, less than half of the sea level variance in the intermediate band is related, through linear correlation, with local wind forcing. Our analysis indicates that the residual coastal sea level signal, not associated with wind forcing, is largely driven remotely by the passage of mesoscale eddies, revealed by satellite altimeter-derived sea level anomaly fields of the central Red Sea. These eddy-driven coastal sea level changes occur on time scales of 10-30 days. They span a range of 0.5 m, and thus constitute an import component of the sea level signal in the coastal Red Sea.

  11. Arctic Sea Level Change From a Reprocessed 2 Decade Altimetric Sea Level Record

    NASA Astrophysics Data System (ADS)

    Andersen, O. B.; Knudsen, P.; Cheng, Y.

    2014-12-01

    For ocean and climate research it is essential to get as accurate long-term altimetric sea level data as possible. However, the accuracy of the altimetric data is frequently degraded in the interior of the Arctic Ocean due to the presence of seasonal or permanent sea ice. We have reprocessed ERS-1/2/Envisat satellite altimetry to develop an improved 20-year sea level dataset for the Arctic Ocean adding in recent retracked Cryosat-2 to bring the record up to 2014 . We have developed both an along-track dataset and 3-day gridded sea level anomaly (SLA) maps from September 1992 to April 2014. A major improvement in data coverage was gained by tailoring the standard altimetric editing criteria to Arctic conditions. The new reprocessed data has significant increased data coverage with between 4 and 10 times the amount of data in regions like the Beaufort Gyre region compared with AVISO and RADS datasets. This allows for a more accurate estimation of sea level changes from satellite altimetry in the Arctic Ocean. The reprocessed dataset exhibit a mean sea level trend of 2.1±1.3 mm/year (without Glacial Isostatic Adjustment correction) covering the Arctic Ocean between 66°N and 82°N with significant higher trend in the Beaufort Gyre region showing an increase in sea level trend at the cm level up to 2011.

  12. Impact of Altimeter Data Processing on Sea Level Studies

    PubMed Central

    Fernandes, M. Joana; Barbosa, Susana; Lázaro, Clara

    2006-01-01

    This study addresses the impact of satellite altimetry data processing on sea level studies at regional scale, with emphasis on the influence of various geophysical corrections and satellite orbit on the structure of the derived interannual signal and sea level trend. The work focuses on the analysis of TOPEX data for a period of over twelve years, for three regions in the North Atlantic: Tropical (0°≤φ≤25°), Sub-Tropical (25°≤φ≤50°) and Sub-Arctic (50°≤φ≤65°). For this analysis corrected sea level anomalies with respect to a mean sea surface model have been derived from the GDR-Ms provided by AVISO by applying various state-of-the-art models for the geophysical corrections. Results show that sea level trend determined from TOPEX altimetry is dependent on the adopted models for the major geophysical corrections. The main effects come from the sea state bias (SSB), and from the application or not of the inverse barometer (IB) correction. After an appropriate modelling of the TOPEX A/B bias, the two analysed SSB models induce small variations in sea level trend, from 0.0 to 0.2 mm/yr, with a small latitude dependence. The difference in sea level trend determined by a non IB-corrected series and an IB-corrected one has a strong regional dependence with large differences in the shape of the interannual signals and in the derived linear trends. The use of two different drift models for the TOPEX Microwave Radiometer (TMR) has a small but non negligible effect on the North Atlantic sea level trend of about 0.1 mm/yr. The interannual signals of sea level time series derived with the NASA and the CNES orbits respectively, show a small departure in the middle of the series, which has no impact on the derived sea level trend. These results strike the need for a continuous improvement in the modelling of the various effects that influence the altimeter measurement.

  13. Simultaneous estimation of lithospheric uplift rates and absolute sea level change in southwest Scandinavia from inversion of sea level data

    NASA Astrophysics Data System (ADS)

    Nielsen, Lars; Hansen, Jens Morten; Hede, Mikkel Ulfeldt; Clemmensen, Lars B.; Pejrup, Morten; Noe-Nygaard, Nanna

    2014-11-01

    Relative sea level curves contain coupled information about absolute sea level change and vertical lithospheric movement. Such curves may be constructed based on, for example tide gauge data for the most recent times and different types of geological data for ancient times. Correct account for vertical lithospheric movement is essential for estimation of reliable values of absolute sea level change from relative sea level data and vise versa. For modern times, estimates of vertical lithospheric movement may be constrained by data (e.g. GPS-based measurements), which are independent from the relative sea level data. Similar independent data do not exist for ancient times. The purpose of this study is to test two simple inversion approaches for simultaneous estimation of lithospheric uplift rates and absolute sea level change rates for ancient times in areas where a dense coverage of relative sea level data exists and well-constrained average lithospheric movement values are known from, for example glacial isostatic adjustment (GIA) models. The inversion approaches are tested and used for simultaneous estimation of lithospheric uplift rates and absolute sea level change rates in southwest Scandinavia from modern relative sea level data series that cover the period from 1900 to 2000. In both approaches, a priori information is required to solve the inverse problem. A priori information about the average vertical lithospheric movement in the area of interest is critical for the quality of the obtained results. The two tested inversion schemes result in estimated absolute sea level rise of ˜1.2/1.3 mm yr-1 and vertical uplift rates ranging from approximately -1.4/-1.2 mm yr-1 (subsidence) to about 5.0/5.2 mm yr-1 if an a priori value of 1 mm yr-1 is used for the vertical lithospheric movement throughout the study area. In case the studied time interval is broken into two time intervals (before and after 1970), absolute sea level rise values of ˜0.8/1.2 mm yr-1 (before 1970) and ˜2.0 mm yr-1 (after 1970) are found. The uplift patterns resulting from the different inversions suggest that the lithospheric post-GIA response changes near the border between the Danish Basin and the Fennoscandian Shield. The obtained patterns of vertical lithospheric movement rates are comparable to results from other studies based on different and similar data types. Main differences between the inversion results and the results from other studies are caused by factors such as the simplifications included in the inversion approach, such as neglecting local sea level variation caused by the dominant wind patterns, and the a priori values chosen for the vertical uplift rates. The tests of the inversion schemes reveal that realistic values of absolute sea level rise and lithospheric uplift may be simultaneously estimated provided that reliable prior knowledge regarding the overall lithospheric uplift in the study area is available beforehand. In the presented parametrizations, only one absolute sea level change rate value is estimated for each studied time interval while several vertical movement rates are found, and the inverse estimate of absolute sea level change rate is practically insensitive with respect to the choice of a priori value of absolute sea level change, as long as the uncertainty assigned to this a priori value is kept sufficiently high.

  14. Sea-level and deep-sea-temperature variability over the past 5.3 million years.

    PubMed

    Rohling, E J; Foster, G L; Grant, K M; Marino, G; Roberts, A P; Tamisiea, M E; Williams, F

    2014-04-24

    Ice volume (and hence sea level) and deep-sea temperature are key measures of global climate change. Sea level has been documented using several independent methods over the past 0.5 million years (Myr). Older periods, however, lack such independent validation; all existing records are related to deep-sea oxygen isotope (δ(18)O) data that are influenced by processes unrelated to sea level. For deep-sea temperature, only one continuous high-resolution (Mg/Ca-based) record exists, with related sea-level estimates, spanning the past 1.5 Myr. Here we present a novel sea-level reconstruction, with associated estimates of deep-sea temperature, which independently validates the previous 0-1.5 Myr reconstruction and extends it back to 5.3 Myr ago. We find that deep-sea temperature and sea level generally decreased through time, but distinctly out of synchrony, which is remarkable given the importance of ice-albedo feedbacks on the radiative forcing of climate. In particular, we observe a large temporal offset during the onset of Plio-Pleistocene ice ages, between a marked cooling step at 2.73 Myr ago and the first major glaciation at 2.15 Myr ago. Last, we tentatively infer that ice sheets may have grown largest during glacials with more modest reductions in deep-sea temperature. PMID:24739960

  15. Changes in Sea Levels around the British Isles Revisited (Invited)

    NASA Astrophysics Data System (ADS)

    Teferle, F. N.; Hansen, D. N.; Bingley, R. M.; Williams, S. D.; Woodworth, P. L.; Gehrels, W. R.; Bradley, S. L.; Stocchi, P.

    2009-12-01

    Recently a number of new and/or updated sources for estimates of vertical land movements for the British Isles have become available allowing the relative and average changes in sea levels for this region to be revisited. The geodetic data set stems from a combination of re-processed continuous Global Positioning System (GPS) measurements from stations in the British Isles and from a global reference frame network, and absolute gravity (AG) measurements from two stations in the British Isles. The geologic data set of late Holocene sea level indicators has recently been updated, now applying corrections for the 20th century sea level rise, syphoning effect and late Holocene global ice melt, and expanded to Northern Ireland and Ireland. Several new model predictions of the glacial isostatic adjustment (GIA) process active in this region form the modelling data set of vertical land movements for the British Isles. Correcting the updated revised local reference (RLR) trends from the Permanent Service for Mean Sea Level (PSMSL) with these vertical land movement data sets, regional and averaged changes in sea levels around the British Isles have been investigated. Special focus is thereby also given to the coastal areas that have recently been identified within the UK Climate Projections 2009.

  16. How Much Are Floridians Willing to Pay for Protecting Sea Turtles from Sea Level Rise?

    NASA Astrophysics Data System (ADS)

    Hamed, Ahmed; Madani, Kaveh; Von Holle, Betsy; Wright, James; Milon, J. Walter; Bossick, Matthew

    2016-01-01

    Sea level rise (SLR) is posing a great inundation risk to coastal areas. Some coastal nesting species, including sea turtle species, have experienced diminished habitat from SLR. Contingent valuation method (CVM) was used in an effort to assess the economic loss impacts of SLR on sea turtle nesting habitats for Florida coasts; and to elicit values of willingness to pay (WTP) of Central Florida residents to implement certain mitigation strategies, which would protect Florida's east coast sea turtle nesting areas. Using the open-ended and dichotomous choice CVM, we sampled residents of two Florida communities: Cocoa Beach and Oviedo. We estimated the WTP of households from these two cities to protect sea turtle habitat to be between 42 and 57 per year for 5 years. Additionally, we attempted to assess the impact of the both the respondents' demographics and their perception toward various situations on their WTP value. Findings include a negative correlation between the age of a respondent and the probability of an individual willing to pay the hypothetical WTP amount. We found that WTP of an individual was not dependent on prior knowledge of the effects of SLR on sea turtle habitat. The greatest indicators of whether or not an individual was willing to pay to protect sea turtle habitat were the respondents' perception regarding the trustworthiness and efficiency of the party which will implement the conservation measures and their confidence in the conservation methods used. Respondents who perceive sea turtles having an effect on their life were also more likely to pay.

  17. Late Holocene land- and sea-level changes in the British Isles: implications for future sea-level predictions

    NASA Astrophysics Data System (ADS)

    Gehrels, W. Roland

    2010-07-01

    Four decades of palaeosea-level research in the British Isles have produced a large dataset of age-altitude curves of postglacial sea-level changes. Patterns of late Holocene relative sea-level change reveal the persistent influence of the British/Irish Ice Sheet and the larger Scandinavian Ice Sheet on contemporary rates of vertical land movements. The Shennan and Horton (2002) map of late Holocene relative land movements has been used in future sea-level rise predictions by the United Kingdom Climate Impact Programme in their 2002 assessment (UKCIP02), but has been mistaken for a map of absolute land movements. In this paper, land-motion data for Britain are extracted from the Shennan and Horton (2002) relative sea-level data, and a new map of crustal land movements is presented which also includes Ireland. This procedure takes into account the regional 20th century sea-level rise (˜0.14 m) and the process of ocean syphoning ( i.e. a global fall in sea level of ˜0.3 mm/yr due to GIA induced ocean-floor lowering and re-distribution of ocean mass). The calculated land-motion rates also depend on the global late Holocene ice-equivalent sea-level change, given by the Intergovernmental Panel on Climate Change as 0.0-0.2 mm/yr. Accounting for these processes reduces the misfit between geological observations of vertical land motion and those independently derived from gravity-aligned Global Positioning System (AG GPS) measurements and shows that UKCIP02 has underestimated land subsidence in southern Britain and over-estimated land uplift in Scotland, both by 0.1-0.2 mm/yr. A best fit between GPS and geological estimates of land movements in Britain is achieved for a global long-term eustatic sea-level fall of ca 0.2 mm/yr, suggesting some global ice expansion in the late Holocene, rather than melt. If this is correct, uplift rates in Scotland would be lower and subsidence rates in southern Britain would be faster (by 0.4-0.5 mm/yr) than estimated by UKCIP02. More high-quality late Holocene relative sea-level data are required to quantify vertical land motion as accurately as possible, especially near large coastal population centres, for input into regional scenarios of future sea-level rise.

  18. Understanding sea-level variations in the Bay of Bengal

    NASA Astrophysics Data System (ADS)

    de Juan, J.; Davis, J. L.; Hill, E. M.; Tamisiea, M. E.; Ponte, R. M.; Vinogradova, N. T.

    2012-12-01

    Sea level is affected by a wide range of processes, resulting in a response that varies on seasonal, interannual, and decadal time scales, and that has clear regional variations. Understanding such variability is important in order to quantify and interpret global trends in long-term sea level. One cause of this variability, of many, is the seasonal exchange of water between the continents and the ocean, which induces changes in the shape and gravity field of the Earth. This so-called 'self-attraction and loading' (SAL) causes a spatial and temporal variation of sea level, with an annual amplitude that ranges from ~2 mm to >18 mm. Previous studies show that the effect of SAL on the annual cycle of sea level is larger in the Bay of Bengal than anywhere else on Earth. In addition, tide-gauge measurements of the annual cycle in sea level show among the largest disagreements with ocean model predictions and near-coastal altimeter measurements in this region. The study of sea level in the Bay of Bengal is important, both socially and scientifically. Three rivers converge in Bangladesh, with one of the world's highest annual discharge, of ~1300 GT/yr. The large delta covers the highly populated regions of southern Bangladesh and West Bengal. River flow is highly seasonal, with almost all discharge taking place during the summer monsoon. These conditions result in widespread flooding over Bangladesh every summer, with ~100 GT of water stored within Bangladesh during these events, as observed with GRACE and in-situ measurements. This large hydrological load is the cause for the observed large annual SAL effect in this region, and may account for at least part of the discrepancy between tide-gauge measurements and ocean-model predictions. Furthermore, comparison with measurements suggests that the hydrology models used to estimate the global SAL effect on the annual sea-level cycle may be underestimating the water load over this region. The problem is compounded by the fact that this river system has also the largest rates of sediment discharge, of ~1 GT/yr, resulting in a highly dynamic delta. Additionally, due to the low elevation of the coastal areas, changes in shoreline location may be occurring. Careful inspection of tide-gauge RSL time series from this area reveals large temporal and regional variations in the annual cycle and at longer periods. These factors suggest that the variations in sea level may also be strongly impacted by local effects.

  19. Sea level changes in the Holocene

    SciTech Connect

    Tanner, W.F. )

    1993-03-01

    Beach ridge data provide much information on the history of sea level changes through all of Holocene time. Two data sets start at about 12,000 B.P., one of them essentially continuous to now with data every 40--50 yrs. Another starting at 7,600 B.P. is continuous to the present. Others span the last 3,200 years. These records agree reasonably closely, and show the Little Ice Age (since 1,200 A.D.). The sea level changes in these data include the following: (a) Early Holocene crisis, about 8,000 B.P. The Swedish (Baltic Sea) record ends about this time, the Hudson Bay record starts at roughly this time, and the Danish record has a 300--500-year gap at about this time. From the latter, it appears that sea level rose sharply, shortly before 8,000 B.P., and fell again shortly after 8,000 B.P. These were the largest changes in Holocene time. The vertical change may have been as much as 12--18 meters, and the rate of change as much as 5--8 cm/yr, perhaps the maximum possible. In stable areas, evidence for these changes are now 25--30 meters below sea level. (b) Early Holocene general rise, up to about 8,000 B.P. Evidence for this is now known only on uplifted coasts. (c) Middle Holocene high, 2 m above present MSL 7,000--5,500 B.P. (d) Middle Holocene low, 3--4 m below present MSL 5,000--3,500 B.P. (e) Several changes up to 2 meters, especially since 3,000 B.P. In general, rates of change have been close to 1 cm/yr (major exceptions noted above). The only persistent interval was that between beach ridges; each ridge and its associated swale seem to have been built by a sea-level rise-and-fall couplet, having dimensions so small (perhaps 5--30 cm) that they could be overlooked easily on tide-gauge records. The average apparent time interval was 35--50 years.

  20. Consequences of sea level variability and sea level rise for Cuban territory

    NASA Astrophysics Data System (ADS)

    Hernández, M.; Martínez, C. A.; Marzo, O.

    2015-03-01

    The objective of the present paper was to determine a first approximation of coastal zone flooding by 2100, taking into account the more persistent processes of sea level variability and non-accelerated linear sea level rise estimation to assess the main impacts. The annual linear rate of mean sea level rise in the Cuban archipelago, obtained from the longest tide gauge records, has fluctuated between 0.005 cm/year at Casilda and 0.214 cm/year at Siboney. The main sea level rise effects for the Cuban coastal zone due to climate change and global warming are shown. Monthly and annual mean sea level anomalies, some of which are similar to or higher than the mean sea level rise estimated for halfway through the present century, reinforce the inland seawater penetration due to the semi-daily high tide. The combination of these different events will result in the loss of goods and services, and require expensive investments for adaption.

  1. Pulse compression and sea level tracking in satellite altimetry

    NASA Technical Reports Server (NTRS)

    Chelton, Dudley B.; Walsh, Edward J.; Macarthur, John L.

    1989-01-01

    An account is given of the pulse-compression technique, in which a radar altimeter transmits a relatively long pulse and processes the returned signal in a way equivalent to transmitting a very short one and measuring the returned power in a sequence of range gates. The effective short pulse enhances the range resolution that would be obtained from the actual long pulse. Pulse compression and sea-level tracking are important to the overall error budget for altimetric estimates of sea level. Attention is presently given to the high degree of accuracy required for the NASA TOPEX altimeter scheduled for launch in mid-1992.

  2. Coastal subsidence and relative sea level rise

    USGS Publications Warehouse

    Ingebritsen, Steven E.; Galloway, Devin L.

    2014-01-01

    Subsurface fluid-pressure declines caused by pumping of groundwater or hydrocarbons can lead to aquifer-system compaction and consequent land subsidence. This subsidence can be rapid, as much as 30 cm per year in some instances, and large, totaling more than 13 m in extreme examples. Thus anthropogenic subsidence may be the dominant contributor to relative sea-level rise in coastal environments where subsurface fluids are heavily exploited. Maximum observed rates of human-induced subsidence greatly exceed the rates of natural subsidence of unconsolidated sediments (~0.1–1 cm yr−1) and the estimated rates of ongoing global sea-level rise (~0.3 cm yr−1).

  3. Hurricanes, sea level rise, and coastal change

    USGS Publications Warehouse

    Sallenger,, Asbury H., Jr.

    2011-01-01

    Sixteen hurricanes have made landfall along the U.S. east and Gulf coasts over the past decade. For most of these storms, the USGS with our partners in NASA and the U.S. Army Corps of Engineers have flown before and after lidar missions to detect changes in beaches and dunes. The most dramatic changes occurred when the coasts were completely submerged in an inundation regime. Where this occurred locally, a new breach was cut, like during Hurricane Isabel in North Carolina. Where surge inundated an entire island, the sand was stripped off leaving marshy outcrops behind, like during Hurricane Katrina in Louisiana. Sea level rise together with sand starvation and repeated hurricane impacts could increase the probabilities of inundation and degrade coasts more than sea level rise alone.

  4. Coastal subsidence and relative sea level rise

    NASA Astrophysics Data System (ADS)

    Ingebritsen, S. E.; Galloway, D. L.

    2014-09-01

    Subsurface fluid-pressure declines caused by pumping of groundwater or hydrocarbons can lead to aquifer-system compaction and consequent land subsidence. This subsidence can be rapid, as much as 30 cm per year in some instances, and large, totaling more than 13 m in extreme examples. Thus anthropogenic subsidence may be the dominant contributor to relative sea-level rise in coastal environments where subsurface fluids are heavily exploited. Maximum observed rates of human-induced subsidence greatly exceed the rates of natural subsidence of unconsolidated sediments (˜0.1-1 cm yr-1) and the estimated rates of ongoing global sea-level rise (˜0.3 cm yr-1).

  5. A sea-level recorder for tectonic studies

    NASA Technical Reports Server (NTRS)

    Bilham, R.

    1977-01-01

    In the past tide gauges have provided valuable information concerning the vertical ground deformation associated with major earthquakes. Although tide-gauge data contains numerous sources of noise, a spacing of less than 40 km between gauges is indicated for a useful study of dilatant behavior, and a spacing of less than 80 km may be adequate for the study of crustal downwarping in island arcs. An inexpensive tide gauge which is designed to provide a continuous record of sea level with a measurement precision of 1 mm is described. Hydraulic filtering is incorporated into the instrument to attenuate daily tides relative to longer period variations of sea level. The instrument is designed to operate from flashlight batteries for a year unattended and to withstand temporary submersion as might be caused by tsunamis. Several of these sea-level recorders have been installed in seismic gaps in the Aleutians and in the Caribbean.

  6. Rising Sea Levels: Truth or Scare?

    ERIC Educational Resources Information Center

    Peacock, Alan

    2007-01-01

    When "ITV News" ran an item that shocked the author, about rising sea levels that will have caused the entire evacuation of the islands by the end of this year, he began to wonder whether the Pacific Ocean is really rising as fast as this. The media reporting of such things can be a double-edged sword. On the one hand, it brought to the author's…

  7. Internal and external forcing of sea level variability in the Black Sea

    NASA Astrophysics Data System (ADS)

    Volkov, Denis L.; Landerer, Felix W.

    2015-11-01

    The variability of sea level in the Black Sea is forced by a combination of internal and external processes of atmospheric, oceanic, and terrestrial origin. We use a combination of satellite altimetry and gravity, tide gauge, river discharge, and atmospheric re-analysis data to provide a comprehensive up-to-date analysis of sea level variability in the Black Sea and to quantify the role of different environmental factors that force the variability. The Black Sea is part of a large-scale climatic system that includes the Mediterranean and the North Atlantic. The seasonal sea level budget shows similar contributions of fresh water fluxes (precipitation, evaporation, and river discharge) and the Black Sea outflow, while the impact of the net surface heat flux is smaller although not negligible. We find that the nonseasonal sea level time series in the Black and Aegean seas are significantly correlated, the latter leading by 1 month. This lag is attributed to the adjustment of sea level in the Black Sea to externally forced changes of sea level in the Aegean Sea and to the impact of river discharge. The nonseasonal sea level budget in the Black Sea is dominated by precipitation and evaporation over the sea itself, but external processes such as river discharge and changes in the outflow can also cause some large synoptic-scale sea level anomalies. Sea level is strongly coupled to terrestrial water storage over the Black Sea drainage basin, which is modulated by the North Atlantic Oscillation (NAO). We show that during the low/high NAO southwesterly/northeasterly winds near the Strait of Gibraltar and southerly/northerly winds over the Aegean Sea are able to dynamically increase/decrease sea level in the Mediterranean and Black seas, respectively.

  8. History of coral reefs and sea level

    SciTech Connect

    Fairbridge, R.W.

    1985-01-01

    Charles Darwin proposed crustal subsidence for atoll growth, on the Beagle, between England and Brazil, before even seeing a coral reef, on the basis of charts and discussions with Captain Fitzroy. Relative change of sea level due to crustal movements was then well-accepted from evidence of raised strandlines in Scandinavia and Scotland and sunken forests in England. Darwin added global change of sea level (tectonoeustasy) caused by remote tectonic activity, as explained by Robert Chambers (1848, p. 319). The glacioeustasy concept was mooted soon afterwards, though the term itself came later. When Suess in 1888 proposed eustatic change, he had in mind Archimedian displacement of water by sediment or lava accumulation on the sea floor. Integrated ideas of reef development also came in the 20th century. The powerful arguments against Darwin were led by Murray with his solution hypothesis, which can not be judged as good observation but from a narrow viewpoint. The Royal Society reef borings at Funafuti were heroic but at the same time misread. Subsequently came isotopic geochemistry, absolute dating, the Milankovitch insolation theory, and plate tectonics. And much more field work. The result is an integrated reef growth theory.

  9. On the effect of the sampling frequency of sea level measurements on return period estimate of extremes—Southern European examples

    NASA Astrophysics Data System (ADS)

    Tsimplis, M. N.; Marcos, M.; Pérez, B.; Challenor, P.; Garcia-Fernandez, M. J.; Raicich, F.

    2009-10-01

    Estimates of extreme sea levels and return periods have been based mainly on hourly sampling rates. Technological development has enabled the sampling rates to increase and sampling rates of 5-10 min are becoming increasingly common. In this paper we explore the relationship between extreme sea levels and estimated return periods based on hourly and shorter sampling periods in three tide-gauges one at the Atlantic coasts of Spain (Coruña), one in the western Mediterranean (Malaga) and one in the N. Adriatic (Trieste). Significant differences of several centimetres are found in the hourly and 5 min extremes. These reflect in significant underestimation of the 50-year return levels which in Trieste reach 38 cm. A theoretical relationship between the high and the low sampling rate of extremes is also tested. Thus updated 50-year return levels for the Mediterranean and the coasts of the Iberian peninsula are produced assuming that the differences identified in the various stations generalise to other tide-gauge (hourly) records for which hourly values have been analysed earlier.

  10. Tracking multidecadal trends in sea level using coral microatolls

    NASA Astrophysics Data System (ADS)

    Majewski, Jedrzej; Pham, Dat; Meltzner, Aron; Switzer, Adam; Horton, Benjamin; Heng, Shu Yun; Warrick, David

    2015-04-01

    Tracking multidecadal trends in sea level using coral microatolls Jędrzej M. Majewski 1, Dat T. Pham1, Aron J. Meltzner 1, Adam D. Switzer 1, Benjamin P. Horton2, Shu Yun Heng1, David Warrick3, 1 Earth Observatory of Singapore, Nanyang Technological University, Singapore 2 Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA 3 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA Coral microatolls can be used to study relative sea-level change at multidecadal timescales associated with vertical land movements, climate induced sea-level rise and other oceanographic phenomena such as the El Niño/Southern Oscillation (ENSO) or Indian Ocean Dipole (IOD) with the assumption that the highest level of survival (HLS) of coral microatolls track sea level over the course of their lifetimes. In this study we compare microatoll records covering from as early as 1883 through 2013, from two sites in Indonesia, with long records (>20 years) from proximal tide gauges, satellite altimetry, and other sea-level reconstructions. We compared the HLS time series derived from open-ocean and moated (or ponded) microatolls on tectonically stable Belitung Island and a potentially tectonically active setting in Mapur Island, with sea-level reconstructions for 1950-2011. The sea-level reconstructions are based on ground and satellite measurements, combining a tide model with the Estimating the Circulation and Climate of the Ocean (ECCO) model. Our results confirm that open-ocean microatolls do track low water levels at multi decadal time scales and can be used as a proxy for relative sea level (RSL) over time. However, microatolls that are even partially moated are unsuitable and do not track RSL; rather, their growth patterns likely reflect changes in the elevation of the sill of the local pond, as reported by earlier authors. Our ongoing efforts will include an attempt to recognize similarities in moated microatolls that may be helpful in identifying fossil microatolls that grew in moated settings. We will also attempt to build guidelines for recognizing and excluding living ponded microatolls in the field.

  11. Probabilistic assessment of sea level during the last interglacial stage.

    PubMed

    Kopp, Robert E; Simons, Frederik J; Mitrovica, Jerry X; Maloof, Adam C; Oppenheimer, Michael

    2009-12-17

    With polar temperatures approximately 3-5 degrees C warmer than today, the last interglacial stage (approximately 125 kyr ago) serves as a partial analogue for 1-2 degrees C global warming scenarios. Geological records from several sites indicate that local sea levels during the last interglacial were higher than today, but because local sea levels differ from global sea level, accurately reconstructing past global sea level requires an integrated analysis of globally distributed data sets. Here we present an extensive compilation of local sea level indicators and a statistical approach for estimating global sea level, local sea levels, ice sheet volumes and their associated uncertainties. We find a 95% probability that global sea level peaked at least 6.6 m higher than today during the last interglacial; it is likely (67% probability) to have exceeded 8.0 m but is unlikely (33% probability) to have exceeded 9.4 m. When global sea level was close to its current level (>or=-10 m), the millennial average rate of global sea level rise is very likely to have exceeded 5.6 m kyr(-1) but is unlikely to have exceeded 9.2 m kyr(-1). Our analysis extends previous last interglacial sea level studies by integrating literature observations within a probabilistic framework that accounts for the physics of sea level change. The results highlight the long-term vulnerability of ice sheets to even relatively low levels of sustained global warming. PMID:20016591

  12. The partition of regional sea level variability

    NASA Astrophysics Data System (ADS)

    Forget, Gaël; Ponte, Rui M.

    2015-09-01

    The existing altimetric record offers an unprecedented view of sea level (ζ) variability on a global scale for more than 2 decades. Optimal inference from the data involves appropriate partition of signal and noise, in terms of relevant scales, physical processes and forcing mechanisms. Such partition is achieved here through fitting a general circulation model to altimeter and other datasets to produce a "best" estimate of ζ variability directly forced by the atmosphere-the signal of primary interest here. In this context noise comes primarily from instrument errors and meso-scale eddies, as expected, but spatial smoothing effectively reduces this noise. A separate constraint is thus formulated to measure the fit to monthly, large-scale altimetric variability that unlike the daily, pointwise constraint shows a high signal-to-noise ratio. The estimate is explored to gain insight into dynamics, forcing, and other factors controlling ζ variability. Contributions from thermo-steric, halo-steric and bottom pressure terms are all important depending on region, but slopes of steric spectra (red) and bottom pressure spectra (white) are nearly invariant with latitude. Much ζ variability can be represented by a seasonal cycle and linear trend, plus a few EOFs that can be associated with known modes of climate variability and/or with topographic controls. Both wind and buoyancy forcing are important. The response is primarily basin-bound in nature, but uneven patterns of propagation across basin boundaries are clearly present, with the Pacific being able to affect large portions of the Indian and Atlantic basins, but the Atlantic affecting mostly the Arctic.

  13. The Puzzle of Global Sea Level Rise

    NASA Astrophysics Data System (ADS)

    Singer, S. F.

    2002-05-01

    Credible geologic evidence gives a total rise in global sea level of 120 meters since the Last Glacial Maximum (LGM) of 18,000 years ago. After rising rapidly, the rate of SL rise slowed considerably about 5000 BP -- after continental ice sheets covering North America and Europe had melted away. As measured by tide gauges and corrected for Glacial Isostatic Adjustment, the rate during the 20th century was only about 18 cm/century and showed no acceleration in spite of a rapid climate warming before 1940 [1]. Thermal expansion from ocean warming and melting of mountain glaciers can explain only half that value - unless one were to adopt a much lower rate of rise favored by the IPCC-TAR [2]. The discrepancy is actually worse than suggested by Douglas and Peltier -- since increased precipitation and consequent ice accumulation over the Antarctic Continent (leading to a drop in SL) offsets much of the rise caused by warming. Two conclusions follow: (1) With thermal expansion plus glacier melting nearly canceled by Antarctic Continent ice accumulation [3], SL rise should be reasonably insensitive to decadal-scale climate changes, including a possible greenhouse warming by human activities. In our view, the observed rise can best be explained by the slow, millennial-scale melting of Antarctic ice sheets that has been ongoing since the LGM. (2) Hence we predict that SL rise during the 21st century and beyond will continue to be 18 cm; and there is little anyone can do about this. 1. B. C. Douglas and W. R. Peltier. Physics Today, March 2002. pp.35-40 2. IPCC-TAR (Intergovernmental Panel on Climate Change, Third Assessment Report). The Science of Climate Change. Cambridge Univ. Press 2001 3. S. F. Singer. Hot Talk, Cold Science: Global Warming's Unfinished Debate. The Independent Institute (Oakland, CA). Second edition 1999.

  14. Monitoring Sea Level At L'Estartit, Spain

    NASA Astrophysics Data System (ADS)

    Martinez-Benjamin, J.; Ortiz Castellon, M.; Martinez-Garcia, M.; Talaya, J.; Rodriguez Velasco, G.; Perez, B.

    2007-12-01

    Sea level is an environmental variable which is widely recognised as being important in many scientific disciplines as a control parameter for coastal dynamical processes or climate processes in the coupled atmosphere-ocean systems, as well as engineering applications. A major source of sea-level data are the national networks of coastal tide gauges, in Spain belonging to different institutions as the Instituto Geográfico Nacional (IGN), Puertos del Estado (PE), Instituto Hidrográfico de la Marina (IHM), Ports de la Generalitat, etc. Three Begur Cape experiences on radar altimeter calibration and marine geoid mapping made on 1999, 2000 and 2002 are overviewed. The marine geoid has been used to relate the coastal tide gauge data from l'Estartit harbour to off-shore altimetric data. The necessity to validate and calibrate the satellite's altimeter due to increasing needs in accuracy and long term integrity implies establishing calibration sites with enhanced ground based methods for sea level monitoring. A technical Spanish contribution to the calibration experience has been the design of GPS buoys and GPS catamaran taking in account the University of Colorado at Boulder and Senetosa/Capraia designs. Altimeter calibration is essential to obtain an absolute measure of sea level, as are knowing the instrument's drifts and bias. Specially designed tidegauges are necessary to improve the quality of altimetric data, preferably near the satellite track. Further, due to systematic differences a month instruments onboard different satellites, several in-situ calibrations are essentials to tie their systematic differences. L'Estartit tide gauge is a classical floating tide gauge set up in l'Estartit harbour (NE Spain) in 1990. It provides good quality information about the changes in the sea heights at centimetre level, that is the magnitude of the common tides in theMediterranean. In the framework of a Spanish Space Project, ref:ESP2001- 4534-PE, the instrumentation of sea level measurements as been improved by providing this site with a radar tide gauge and with a continuous GPS station nearby. This will have a significant incidence in the satellite altimeter calibration activities. The radar tide gauge with data recorder and transmitter is a Datamar 3000C with 26 GHz frequency, 1mm resolution, 8º beam width incorporating a GPS receiver for automatic clock synchronization and a Thales Navigation Internet-Enabled GPS Continuous Geodetic Reference Station (iCGRS) with a choke ring antenna. It is intended that the overall system will constitute a CGPS Station of the ESEAS (European Sea Level) and TIGA (GPS Tide Gauge Benchmark Monitoring) networks. A Partenavia P-68 airborne LIDAR campaign carrying an Optech Lidar ALT-3025 has been made in June 2007 to test the potential of Lidar to connect sea level measurements from tide gauges at the coast with satellite (as Jason-1 or Envisat) altimetry measurements offshore. The calibrated airborne Lidar can then be used over ocean to detect the sea surface height. In consequence, the objective is to check that the coastal sea level can be observed with GPS buoys and may be Lidar campaigns for get detailed regional geoid and sea surface topography models for referencing satellite altimeter measurements.

  15. A global observing system for monitoring and prediction of sea level change

    NASA Astrophysics Data System (ADS)

    Fu, Lee-Lueng

    The rise of global sea level is a direct consequence of climate change. A one-meter rise by the end of the century is estimated to have global economic impacts by trillions of US dollars and displacement of 10% of the world’s population if no adaptation is applied. Before the advent of satellite observations of sea surface height with radar altimetry, it was not possible to make direct determination of the global mean sea level. The sparsely located tide gauges were not able to sample the uneven spatial distribution of sea level change, leading to biased measurement. The 20-year record from satellite altimetry is the first directly measured time series of the global mean sea level. The satellite’s uniform global sampling also reveals the complex geographic pattern of sea level change over the past 20 years, underscoring the uncertainty from sparse tide gauge measurement. The contributions to recent sea level rise have roughly equal partitions among the steric effect from ocean warming, the melting of mountain glaciers, and the melting of polar ice sheets. The measurement of the change of Earth’s gravity field from the GRACE Mission has for the first time provided direct observation of the mass added to the ocean from ice melting. The difference between altimetry and gravity measurements is attributed to the steric sea level change, which has been observed by an in-situ network of float measurement (Argo). The intercomparison of satellite and in-situ observations has provided cross-calibration and mutual validation of the measurement system, demonstrating a calibrated measurement system for global sea level. The ability to diagnose sea level change in terms of its various components represents a key step towards understanding the physical processes. In order to assess the societal impact of sea level rise, one must be able to predict its regional pattern, which involves a host of other factors. The prediction of sea level change thus requires an Earth system science approach. The system consists of the following elements: (1) the measurement of sea level relative to the land, (2) the measurement of the main components of the ice mass contribution to sea level (i.e. surface mass balance and ice dynamics), (3) the steric contribution to sea level, (4) the mechanisms determining the geographic distribution of sea level change; and (5) the integration of these observations in advanced numerical models for hindcast and projection of sea level change. This global observing system will be discussed in the presentation.

  16. Estimating sea-level allowances for Atlantic Canada under conditions of uncertain sea-level rise

    NASA Astrophysics Data System (ADS)

    Greenan, B.; Zhai, L.; Hunter, J.; James, T. S.; Han, G.

    2015-03-01

    This paper documents the methodology of computing sea-level rise allowances for Atlantic Canada in the 21st century under conditions of uncertain sea-level rise. The sea-level rise allowances are defined as the amount by which an asset needs to be raised in order to maintain the same likelihood of future flooding events as that site has experienced in the recent past. The allowances are determined by combination of the statistics of present tides and storm surges (storm tides) and the regional projections of sea-level rise and associated uncertainty. Tide-gauge data for nine sites from the Canadian Atlantic coast are used to derive the scale parameters of present sea-level extremes using the Gumbel distribution function. The allowances in the 21st century, with respect to the year 1990, were computed for the Intergovernmental Panel on Climate Change (IPCC) A1FI emission scenario. For Atlantic Canada, the allowances are regionally variable and, for the period 1990-2050, range between -13 and 38 cm while, for the period 1990-2100, they range between 7 and 108 cm. The negative allowances in the northern Gulf of St. Lawrence region are caused by land uplift due to glacial isostatic adjustment (GIA).

  17. Steric sea level change: An arctic perspective

    NASA Astrophysics Data System (ADS)

    Steele, M.; Ermold, W.

    2005-12-01

    Is the Arctic Ocean getting fresher in response to an accelerated hydrologic cycle? Is it warming like most of the rest of the World Ocean? And what is the combined effect of heat and freshwater changes on steric sea level? These are the questions that we address in this talk. We have analyzed hydrographic (temperature and salinity) data from the World Ocean Database (WOD'01, published by the National Oceanographic Data Center), from the Arctic Ocean Database (AOA, published by the Environmental Working Group), and from selected individual cruises over the North Pacific, North Atlantic, and Arctic Oceans. The period of analysis is 1950-2000. The data are integrated over 0-1000 m depth and presented as freshwater content (halosteric height), heat content (thermosteric height), and dynamic topography (total steric height). First, we present the long-term mean of these quantities from both polar stereographic and sector zonal average viewpoints. These clearly illustrate the steric height minimum in the Nordic Seas that drives 2 circulation branches: (i) the northern limb of the Atlantic Ocean Meridional Overturning Circulation and (ii) the "arctic backdoor" i.e., the flow of freshwater across the Arctic Ocean from the Pacific to the Atlantic Ocean. In terms of change, we analyze annual anomalies, and find in the North Atlantic subpolar gyre freshening, cooling, and steric height decrease in the late 1960s, presumably in response to Arctic Ocean sea ice export during the Great Salinity Anomaly. About five years later, steric height dropped precipitously in the Arctic Ocean, and the Nordic Seas responded with a freshening and steric height rise. These trends generally continued through the 1980s, but started to reverse during the 1990s. Meanwhile, the North Pacific Ocean warmed and steric height rose during 1975-1995, with weak freshwater trends, and a reversal after 1995. Comparing steric height trends over the 1960s-1990s, we see little change in the steric height gradient between the North Pacific Ocean and the Nordic Sea, but some evidence for an increase in this gradient between the North Pacific Ocean and the Labrador Sea. The implications for circulation will be discussed.

  18. Past Sea Level Reconstruction and Variability of Sea Level Trend Patterns over 1958-2005 in the Mediterranean Sea basin

    NASA Astrophysics Data System (ADS)

    Meyssignac, B.; Cazenave, A. A.; Morrow, R. A.; Llovel, W.; Maisongrande, P.; Fenoglio-Marc, L.

    2009-12-01

    For the past decades, there are no direct basin-scale observations informing on the spatial trend patterns in Mediterranean sea level. Yet it is important to know the dominant modes of regional variability on interannual/decadal/multidecadal time scale in the Mediterranean basin and their driving mechanisms. For that purpose, we have developed a reconstruction method of past Mediterranean sea level (since 1958) that combines long tide gauge records of limited coverage and 2-D sea level patterns based on runs from two different Ocean General Circulation Models (OGCMs). Instead of using 2-D spatial patterns from satellite altimetry (as done in previous studies; e.g., Calafat et al., 2009), here we prefer to use OGCM runs on the past few decades on the assumption that they better capture the decadal variability of the spatial trend patterns. The two OGCMs considered are the ORCA05 run (without data assimilation) over 1958-2005 available from the DRAKKAR project and the SODA reanalyse over 1958-2005 available from GODAE (Carton et al., 2008), assimilating all available in situ temperature, salinity and sea level data. The two sea level reconstructions are compared to each other as well as with previous studies (e.g., Calafat et al., 2009). The dominant modes of temporal variability are discussed and sea level hindcasts at tide gauge sites not used in the analysis are compared to actual observations. Comparisons with steric sea level patterns based on in situ hydrographic data are also presented and discussed with regard to the conclusions of past studies based on tide gauge records analysis.

  19. Sea level variability of the Arabian Sea and its gulfs from tide gauges and satellite altimetry

    NASA Astrophysics Data System (ADS)

    Al-Subhi, Abdullah Mohammed

    Monthly mean sea levels in the Arabian Sea have been investigated for seasonal-to-annual variation and interannual oscillations. Relative Sea level in the Port of Aden is rising either due to the widening sea floor and/or to volume changes caused by thermal expansion. However, a correction is needed for the rate of vertical land movement. Moreover, sea level in general is responding primarily to steric height change, and is low during the late summer to autumn and high during winter to the early summer. Wavelet analysis supports the hypothesis of this study in that the interannual variation present in sea level is due to ENSO oscillations. Relative sea level at Karachi is generally rising. However, since 1960 the RSL trend is falling. Furthermore, seasonal sea level variation at Karachi differs with that in the Gulf of Aden; it is low during winter and both transition periods and high during summer in the west, while in the east it is high in mid-spring. Steric height change is also the main factor affecting sea level in the eastern Gulf of Oman and Makran coast, whereas sea level change in the northwestern part of the Gulf is due to atmospheric pressure. Wavelet transform analysis of sea level data in this area shows an anti-phase between sea level and ENSO for some years and in-phase in others. Sea level trend at Bombay revealed a small response to thermal expansion or interdecadal variability of the Monsoon. At Kandla, the sea level trend is higher than global average values due to possible tectonic activity. Sea level variation due to steric change is high in the early spring to early summer and low during the rest of the year. In contrast to the strong sea level-ENSO in-phase relationship in the Gulf of Aden, wavelet analysis of sea level along the west Indian coast shows a strong in-phase relationship with the Indian Ocean Dipole. Seasonal sea level variability in the Arabian Sea is mainly consistent with steric sea level changes except in places where the atmospheric sea level pressure plays a significant role. Interseasonal sea level variability is in phase with the monsoon seasonal changes whereas the interannual signals show evidence of El Nino/Southern Oscillation on ENSO time-scales, and the Indian Ocean Dipole on decadal time-scales. Century-scale relative sea level trends more or less agree with global averages, but are very site specific and are undoubtedly affected by vertical land motion either from natural or anthropogenic causes.

  20. Sea level trends, interannual and decadal variability in the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Zhang, Xuebin; Church, John A.

    2012-11-01

    Linear trend analysis is commonly applied to quantify sea level change, often over short periods because of limited data availability. However, the linear trend computed over short periods is complicated by large-scale climate variability which can affect regional sea level on interannual to inter-decadal time scales. As a result, the meaning of a local linear sea level trend over the short altimeter era (since 1993; less than 20 years) is unclear, and it is not straightforward to distinguish the regional sea level changes associated with climate change from those associated with natural climate variability. In this study, we use continuous near-global altimeter measurements since 1993 to attempt to separate interannual and decadal sea level variability in the Pacific from the sea level trend. We conclude that the rapid rates of sea level rise in the western tropical Pacific found from a single variable linear regression analysis are partially due to basin-scale decadal climate variability. The negligible sea level rise, or even falling sea level, in the eastern tropical Pacific and US west coast is a result of the combination of decreasing of sea level associated with decadal climate variability and a positive sea level trend. The single variable linear regression analysis only accounts for slightly more than 20% of the observed variance, whereas a multiple variable linear regression including filtered indices of the El Nino-Southern Oscillation and the Pacific Decadal Oscillation accounts for almost 60% of the observed variance.

  1. The role of Argo steric sea level within the global sea level budget

    NASA Astrophysics Data System (ADS)

    von Schuckmann, K.; Sallée, J.-B.; Cabanes, C.; Le Traon, P.-Y.; Gaillard, F.; Speich, S.; Hamon, M.

    2012-04-01

    Precise estimations of global ocean indicators (GOIs) such as global ocean heat content (GOHC) and global steric sea level (GSSL) are necessary to observe the ocean's role in the Earth's climate system. To improve accuracy of these estimations, our knowledge of deep ocean and regional contributions to GOIs needs to be quantified. Data from the global Argo array are used here to analyze these contributionsduring the period 2005 to 2010. GOHC/GMSH rise increases by 25% /35% for the upper 2000m depth compared to the upper ocean 700m depth. A comparison of Argo steric sea level to total sea level from satellite altimetry (AVISO) and ocean mass (GRACE) is performed during this period. We could close the global and regional sea level budgets for 2005 to 2010 in terms of 6-year trends. Results show that largest correlation of global GSSL, ocean mass and global total sea level can be observed in the global tropical basin. Differences of the 6-year trend between global mean total sea level and GSSL in this basin are mostly explained by Argo sampling issues, especially in the - by Argo under sampled - Indonesian Archipelago. The differences of the 6-year trend in the Southern Ocean can be attributed to mass changes and deep ocean steric changes, whereas in the Northern Ocean mass changes clearly dominate decadal and longer-term variability. The results are only valid under the assumption that no systematic errors remain in either one of the global observing systems, although the comparison of all three observing systems indicates that these errors appear to be small during the years 2005 to 2010.

  2. Modelling sea-level data from China and Malay-Thai Peninsula to infer Holocene eustatic sea-level change

    NASA Astrophysics Data System (ADS)

    Bradley, S.; Milne, G.; Zong, Y.; Horton, B.

    2008-12-01

    Late Devensian relative sea-level observations record changes in global sea level driven by a complex interplay between tectonic, isostatic and climatic processes, and as such have been adopted in many previous modelling studies to provide information on spatial and temporal ice sheet history, rheological earth properties, and global meltwater signals. In regions distant from previously glaciated areas (so-called 'far- field sites'), sea-level observations have been used to constrain the rate and magnitude of the global eustatic sea level change, as these data are primarily sensitive to changes in the global meltwater flux (Clark et al. 1978) Constraining the eustatic component of sea level change is useful since it provides a direct measure of past continental ice volume that can be compared to results obtained from oxygen isotope methods. A second application, which is the primary focus of this study, is the inference of eustatic change during the mid-to-late Holocene. Constraining the eustaic signal provides information on both: (i) the rate and timing of major ice melting at the end of the last deglaciation and (ii) the magnitude of melting during the late Holocene. The latter is an important baseline that can be compared to estimates of global sea-level rise in the 20th century. The typical sea-level pattern at far-field locations is characterized by a steady rise to a mid- Holocene highstand, followed by a slow monotonic fall to present day levels. Previous studies have examined the spatial and temporal variations in the Holocene highstand to arrive at estimates of eustatic change in the mid-to-late Holocene (Nadaka and Lambeck 1989; Flemming et al. 1998; Lambeck 2002; Peltier 2002). While the results of these studies are broadly compatible, there remain significant discrepancies and so it is important to consider additional data to improve constraints on the eustatic signal. This study addresses this aim by considering previously un-modelled Holocene sea-level data from the coast of China - extending from Bohai Bay in the North to Hainan Province in the South, and the Malay-Thai Peninsula. We shall present our inferred eustatic history derived from these data and compare this to the results from the above-mentioned studies.

  3. Mechanisms of long-term mean sea level variability in the North Sea

    NASA Astrophysics Data System (ADS)

    Dangendorf, Sönke; Calafat, Francisco; Øie Nilsen, Jan Even; Richter, Kristin; Jensen, Jürgen

    2015-04-01

    We examine mean sea level (MSL) variations in the North Sea on timescales ranging from months to decades under the consideration of different forcing factors since the late 19th century. We use multiple linear regression models, which are validated for the second half of the 20th century against the output of a state-of-the-art tide+surge model (HAMSOM), to determine the barotropic response of the ocean to fluctuations in atmospheric forcing. We demonstrate that local atmospheric forcing mainly triggers MSL variability on timescales up to a few years, with the inverted barometric effect dominating the variability along the UK and Norwegian coastlines and wind (piling up the water along the coast) controlling the MSL variability in the south from Belgium up to Denmark. However, in addition to the large inter-annual sea level variability there is also a considerable fraction of decadal scale variability. We show that on decadal timescales MSL variability in the North Sea mainly reflects steric changes, which are mostly remotely forced. A spatial correlation analysis of altimetry observations and baroclinic ocean model outputs suggests evidence for a coherent signal extending from the Norwegian shelf down to the Canary Islands. This supports the theory of longshore wind forcing along the eastern boundary of the North Atlantic causing coastally trapped waves to propagate along the continental slope. With a combination of oceanographic and meteorological measurements we demonstrate that ~80% of the decadal sea level variability in the North Sea can be explained as response of the ocean to longshore wind forcing, including boundary wave propagation in the Northeast Atlantic. These findings have important implications for (i) detecting significant accelerations in North Sea MSL, (ii) the conceptual set up of regional ocean models in terms of resolution and boundary conditions, and (iii) the development of adequate and realistic regional climate change projections.

  4. Sea levels changing in response to natural variations

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-12-01

    Scientists have widely accepted that sea levels have been rising since the end of the 19th century due to human activities that warm the planet and melt land-locked ice. Models of future sea level rise suggest that sea levels will continue to increase at an accelerating rate if emissions of greenhouse gases continue at the current rate. This has motivated a number of scientists to search for already existing accelerations in global and regional sea level during the past 2 decades. However, Dangendorf et al. note that current attempts to detect a significant acceleration in sea level rise might have overestimated the role of anthropogenic forcing.

  5. Steric sea level change in the Bay of Bengal: investigating the most variable component of sea level change

    NASA Astrophysics Data System (ADS)

    Uebbing, Bernd; Kusche, Jürgen; Rietbroek, Roelof; Shum, Ck

    2015-04-01

    Regional sea level change is influenced by contributions from mass sources, like melting of glaciers and the ice-sheets in Greenland and Antarctica, as well as steric contributions from changes in temperature and salinity of the oceans. Radar altimetry indicates a sea level trend in the Bay of Bengal of about 6 mm- yr over the time period of 2002-2014, which is significantly larger than the global mean trend. Here, we explain 80% of this rise by steric contributions and 20% by mass-related contributions. The increased rise of sea level in the Bay of Bengal threatens the coastal vulnerability of the surrounding countries like Bangladesh, where this effect is exacerbated in combination with land subsidence of the very low lying coastal areas. The BanD-AID (Bangladesh Delta: Assessment of the Causes of Sea-level Rise Hazards and Integrated Development of Predictive Modeling Towards Mitigation and Adaptation) project tries to assess the current and future sea level rise and its impacts on the people living in the threatened coastal areas. As a part of this, it is necessary to analyze the different mass and steric contributors to the total sea level rise to aid in the prediction of future risks. We use data from radar altimetry and the GRACE mission to separate the total sea level rise into contributions from mass sources and steric changes. In our approach, temporal GRACE gravity data and Jason-1 and -2 along track altimetry data are fitted to time invariant spatial patterns (fingerprints) to avoid problems with GRACE resolution, filtering, geocenter and related issues. Our results show that in the Bay of Bengal the steric component is influenced by annual and interannual phenomena and, at the same time, it is significantly larger compared to the individual mass contributions, which show a linear and relatively stable behavior over time. We validate the steric component of our inversion by comparing it to independent steric estimates from 4-D gridded temperature and salinity products from different ARGO processing facilities. We also compare to the classical approach of subtracting the mass component, estimated by GRACE, from the total sea level change, measured by altimetry. Furthermore, we assess the sensitivity of our inversion to the normalized steric fingerprints, which are either based on ARGO fields or derived from ocean modeling. While most steric changes are taking place in the upper 700 m of the ocean, our inversion also allows us to (indirectly) assess the influence from the deep ocean, which is not negligible for the total steric trend.

  6. A possible connection of Caspian Sea level fluctuations with meteorological factors and seismicity

    NASA Astrophysics Data System (ADS)

    Ozyavas, Aziz; Khan, Shuhab D.; Casey, John F.

    2010-10-01

    The Caspian Sea has exhibited significant, wide-range fluctuations that have been traditionally attributed to variations in climatic agents. The objective of this research is to estimate the hydrologic budget and sea surface heights of the Caspian Sea from 1998 to 2005 to assess the contribution of meteorological and geological process to the Caspian Sea level variations. The water budget of the Caspian Sea from 1998 to 2005 was calculated using the state-of-the-art remote sensing techniques and ground-truth data. The Sea Surface heights of the Caspian Sea were constructed from the refined Topex/Poseidon altimetry data. The National Centers for Environmental Prediction/Department of Energy Reanalysis 2 meteorological data provided all the variables necessary for the Penman method to estimate evaporation over the Caspian Sea. The data of the Tropical Rainfall Measuring Mission were utilized to estimate precipitation onto the Caspian Sea. A strong agreement between the water budget residuals and Caspian Sea level variations signifies that Caspian Sea level oscillations for this time window are essentially controlled by climate-related factors. On the other hand, the relatively larger gaps between the water balance residuals and Caspian Sea level heights during 2000 and 2001 may indicate an impact of seismicity on Caspian Sea level oscillations as a result of two major earthquakes on November 25, 2000.

  7. Long-term sea level trends: Natural or anthropogenic?

    NASA Astrophysics Data System (ADS)

    Becker, M.; Karpytchev, M.; Lennartz-Sassinek, S.

    2014-08-01

    Detection and attribution of human influence on sea level rise are important topics that have not yet been explored in depth. We question whether the sea level changes (SLC) over the past century were natural in origin. SLC exhibit power law long-term correlations. By estimating Hurst exponent through Detrended Fluctuation Analysis and by applying statistics of Lennartz and Bunde, we search the lower bounds of statistically significant external sea level trends in longest tidal records worldwide. We provide statistical evidences that the observed SLC, at global and regional scales, is beyond its natural internal variability. The minimum anthropogenic sea level trend (MASLT) contributes to the observed sea level rise more than 50% in New York, Baltimore, San Diego, Marseille, and Mumbai. A MASLT is about 1 mm/yr in global sea level reconstructions that is more than half of the total observed sea level trend during the XXth century.

  8. Long-term variations in global sea level extremes

    NASA Astrophysics Data System (ADS)

    Marcos, Marta; Calafat, Francisco M.; Berihuete, Ángel; Dangendorf, Sönke

    2015-12-01

    Decadal to multidecadal variations in sea level extremes unrelated to mean sea level changes have been investigated using long tide gauge records distributed worldwide. A state space approach has been applied that provides robust solutions and uncertainties of the time evolving characteristics of extremes, allowing for data gaps and uneven sampling, both common features of historical sea level time series. Two different models have been formulated for the intensity and for the occurrence of extreme sea level events and have been applied independently to each tide gauge record. Our results reveal two key findings: first, the intensity and the frequency of occurrence of extreme sea levels unrelated to mean sea level vary coherently on decadal scales in most of the sites examined (63 out of 77) and, second, extreme sea level changes are regionally consistent, thus pointing toward a common large-scale forcing. This variability of extremes associated with climate drivers should be considered in the framework of climate change studies.

  9. How Much Are Floridians Willing to Pay for Protecting Sea Turtles from Sea Level Rise?

    PubMed

    Hamed, Ahmed; Madani, Kaveh; Von Holle, Betsy; Wright, James; Milon, J Walter; Bossick, Matthew

    2016-01-01

    Sea level rise (SLR) is posing a great inundation risk to coastal areas. Some coastal nesting species, including sea turtle species, have experienced diminished habitat from SLR. Contingent valuation method (CVM) was used in an effort to assess the economic loss impacts of SLR on sea turtle nesting habitats for Florida coasts; and to elicit values of willingness to pay (WTP) of Central Florida residents to implement certain mitigation strategies, which would protect Florida's east coast sea turtle nesting areas. Using the open-ended and dichotomous choice CVM, we sampled residents of two Florida communities: Cocoa Beach and Oviedo. We estimated the WTP of households from these two cities to protect sea turtle habitat to be between $42 and $57 per year for 5 years. Additionally, we attempted to assess the impact of the both the respondents' demographics and their perception toward various situations on their WTP value. Findings include a negative correlation between the age of a respondent and the probability of an individual willing to pay the hypothetical WTP amount. We found that WTP of an individual was not dependent on prior knowledge of the effects of SLR on sea turtle habitat. The greatest indicators of whether or not an individual was willing to pay to protect sea turtle habitat were the respondents' perception regarding the trustworthiness and efficiency of the party which will implement the conservation measures and their confidence in the conservation methods used. Respondents who perceive sea turtles having an effect on their life were also more likely to pay. PMID:26319030

  10. Updating Maryland's sea-level rise projections

    USGS Publications Warehouse

    Boesch, Donald F.; Atkinson, Larry P.; Boicourt, William C.; Boon, John D.; Cahoon, Donald R.; Dalrymple, Robert A.; Ezer, Tal; Horton, Benjamin P.; Johnson, Zoe P.; Kopp, Robert E.; Li, Ming; Moss, Richard H.; Parris, Adam; Sommerfield, Christopher K.

    2013-01-01

    With its 3,100 miles of tidal shoreline and low-lying rural and urban lands, “The Free State” is one of the most vulnerable to sea-level rise. Historically, Marylanders have long had to contend with rising water levels along its Chesapeake Bay and Atlantic Ocean and coastal bay shores. Shorelines eroded and low-relief lands and islands, some previously inhabited, were inundated. Prior to the 20th century, this was largely due to the slow sinking of the land since Earth’s crust is still adjusting to the melting of large masses of ice following the last glacial period. Over the 20th century, however, the rate of rise of the average level of tidal waters with respect to land, or relative sea-level rise, has increased, at least partially as a result of global warming. Moreover, the scientific evidence is compelling that Earth’s climate will continue to warm and its oceans will rise even more rapidly. Recognizing the scientific consensus around global climate change, the contribution of human activities to it, and the vulnerability of Maryland’s people, property, public investments, and natural resources, Governor Martin O’Malley established the Maryland Commission on Climate Change on April 20, 2007. The Commission produced a Plan of Action that included a comprehensive climate change impact assessment, a greenhouse gas reduction strategy, and strategies for reducing Maryland’s vulnerability to climate change. The Plan has led to landmark legislation to reduce the state’s greenhouse gas emissions and a variety of state policies designed to reduce energy consumption and promote adaptation to climate change.

  11. Mid-Pliocene (~3 Ma) relative sea level markers around the world: searching for eustasy.

    NASA Astrophysics Data System (ADS)

    Rovere, Alessio; Raymo, Maureen; Hearty, Paul; MItrovica, Jerry; Austermann, Jacqueline; O'Leary, Michael; Sandstrom, Michael

    2014-05-01

    PLIOMAX (PLIOcene MAXimum sea level) is a five-year research project that aims to increase the accuracy of global sea level estimates for the mid-Pliocene warm period. To achieve its goals, PLIOMAX has organized several field expeditions to identify, measure and date relative sea level markers of mid-Pliocene age from around the globe, and built a network of collaborators expert in different geographic areas and disciplines. In this work we present field data obtained from South Africa, Australia, Italy, Argentina and the US East Coast. In these areas we sampled, measured and dated geological facies related to mid-Pliocene sea level. Most areas yield information on 3 Ma sea levels with an accuracy of few decimeters. In presenting our dataset, we will show how we address the following questions, including: how can we obtain accurate measurements in the field? What is the accuracy of the markers we measure in indicating past relative sea levels? To which point can we trust older literature data? We then show how the elevations of relative sea level markers obtained in the field must be corrected to obtain an estimate of eustatic sea level. These corrections use models of glacial isostatic adjustment and dynamic topography. We discuss uncertainties linked to these models as well as the main issues that are still separating us from obtaining a robust estimate of maximum eustatic sea level during the mid-Pliocene warm period.

  12. Geodetic infrastructure at the Barcelona harbour for sea level monitoring

    NASA Astrophysics Data System (ADS)

    Martinez-Benjamin, Juan Jose; Gili, Josep; Lopez, Rogelio; Tapia, Ana; Pros, Francesc; Palau, Vicenc; Perez, Begona

    2015-04-01

    The presentation is directed to the description of the actual geodetic infrastructure of Barcelona harbour with three tide gauges of different technologies for sea level determination and contribution to regional sea level rise and understanding past and present sea level rise in the Barcelona harbour. It is intended that the overall system will constitute a CGPS Station of the ESEAS (European Sea Level) and TIGA (GPS Tide Gauge Benchmark Monitoring) networks. At Barcelona harbour there is a MIROS radar tide gauge belonging to Puertos del Estado (Spanish Harbours).The radar sensor is over the water surface, on a L-shaped structure which elevates it a few meters above the quay shelf. 1-min data are transmitted to the ENAGAS Control Center by cable and then sent each 1 min to Puertos del Estado by e-mail. The information includes wave forescast (mean period, significant wave height, sea level, etc.This sensor also measures agitation and sends wave parameters each 20 min. There is a GPS station Leica Geosystems GRX1200 GG Pro and antenna AX 1202 GG. The Control Tower of the Port of Barcelona is situated in the North dike of the so-called Energy Pier in the Barcelona harbor (Spain). This tower has different kind of antennas for navigation monitoring and a GNSS permanent station. As the tower is founded in reclaimed land, and because its metallic structure, the 50 m building is subjected to diverse movements, including periodic fluctuations due to temperature changes. In this contribution the 2009, 2011, 2012, 2013 and 2014 the necessary monitoring campaigns are described. In the framework of a Spanish Space Project, the instrumentation of sea level measurements has been improved by providing the Barcelona site with a radar tide gauge Datamar 2000C from Geonica S.L. in June 2014 near an acoustic tide gauge from the Barcelona Harbour installed in 2013. Precision levelling has been made several times in the last two years because the tower is founded in reclaimed land and a little far away from the geographic location of the pulse and acustic radar location on the Europa bridge. The measured settlement rate is about 1cm/year that may be could mask the values registered by the tide gauge. An intercomparison of the results of the three different tide gauges is presented and discussed. These activities has been received funding of the Ministerio de Ciencia e Innovacion under Spanish National Project CGL2009-13435/CLI.

  13. Influence of sea level rise on the dynamics of salt inflows in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Hordoir, Robinson; Axell, Lars; Löptien, Ulrike; Dietze, Heiner; Kuznetsov, Ivan

    2015-10-01

    The Baltic Sea is a marginal sea, located in a highly industrialized region in Central Northern Europe. Saltwater inflows from the North Sea and associated ventilation of the deep exert crucial control on the entire Baltic Sea ecosystem. This study explores the impact of anticipated sea level changes on the dynamics of those inflows. We use a numerical oceanic general circulation model covering both the Baltic and the North Sea. The model successfully retraces the essential ventilation dynamics throughout the period 1961-2007. A suite of idealized experiments suggests that rising sea level is associated with intensified ventilation as saltwater inflows become stronger, longer, and more frequent. Expressed quantitatively as a salinity increase in the deep central Baltic Sea, we find that a sea level rise of 1 m triggers a saltening of more than 1 PSU. This substantial increase in ventilation is the consequence of the increasing cross section in the Danish Straits amplified by a reduction of vertical mixing.

  14. Grain-size based sea-level reconstruction in the south Bohai Sea during the past 135 kyr

    NASA Astrophysics Data System (ADS)

    Yi, Liang; Chen, Yanping

    2013-04-01

    Future anthropogenic sea-level rise and its impact on coastal regions is an important issue facing human civilizations. Due to the short nature of the instrumental record of sea-level change, development of proxies for sea-level change prior to the advent of instrumental records is essential to reconstruct long-term background sea-level changes on local, regional and global scales. Two of the most widely used approaches for past sea-level changes are: (1) exploitation of dated geomorphologic features such as coastal sands (e.g. Mauz and Hassler, 2000), salt marsh (e.g. Madsen et al., 2007), terraces (e.g. Chappell et al., 1996), and other coastal sediments (e.g. Zong et al., 2003); and (2) sea-level transfer functions based on faunal assemblages such as testate amoebae (e.g. Charman et al., 2002), foraminifera (e.g. Chappell and Shackleton, 1986; Horton, 1997), and diatoms (e.g. Horton et al., 2006). While a variety of methods has been developed to reconstruct palaeo-changes in sea level, many regions, including the Bohai Sea, China, still lack detailed relative sea-level curves extending back to the Pleistocene (Yi et al., 2012). For example, coral terraces are absent in the Bohai Sea, and the poor preservation of faunal assemblages makes development of a transfer function for a relative sea-level reconstruction unfeasible. In contrast, frequent alternations between transgression and regression has presumably imprinted sea-level change on the grain size distribution of Bohai Sea sediments, which varies from medium silt to coarse sand during the late Quaternary (IOCAS, 1985). Advantages of grainsize-based relative sea-level transfer function approaches are that they require smaller sample sizes, allowing for replication, faster measurement and higher spatial or temporal resolution at a fraction of the cost of detail micro-palaeontological analysis (Yi et al., 2012). Here, we employ numerical methods to partition sediment grain size using a combined database of marine surface and core samples, and to quantitatively reconstruct sea-level variation since the late Pleistocene in the south Bohai Sea, China. New insights into regional relative sea-level changes since the late Pleistocene are obtained (Yi et al., 2012): (1) The grain size of surface and core samples can be mathematically partitioned using the Weibull distribution into four components. These four components with differing modal sizes and percentages could be interpreted as a long-term suspension component, which only settles under low turbulence conditions, sortable silt and very fine sand components transported by suspension during greater turbulence and bedload transport component, respectively. (2) Through regression and rigorous verification techniques, the reference water level could be reconstructed from sediment grain size. The reconstruction quantitatively extends the regional relative sea-level history to the late Pleistocene, providing a comparatively long dataset to evaluate regional sea-level variability. (3) We find no evidence of a sea-level high stand during MIS3 but rather a substantial regression during 70-30 cal kyr BP and potentially exposed land during 38-20 cal kyr BP. These results for the south Bohai Sea are in good agreement with published global sea-level records for the late Pleistocene, implying similarities between local and global sea-level patterns. Therefore, it is concluded that grain-size based sea-level reconstruction provide results that are comparable to other reconstruction methods and demonstrates great potential application for future works. (The data was shared on http://hurricane.ncdc.noaa.gov/) References Chappell, J., Omura, A., Esat, T., McCulloch, M., Pandolfi, J., Ota, Y., Pillans, B., 1996. Reconciliation of late Quaternary sea levels derived from coral terraces at Huon Peninsula with deep sea oxygen isotope records. Earth and Planetary Science Letters 141, 227-236. Chappell, J., Shackleton, N.J., 1986. Oxygen isotopes and sea level. Nature 324, 137-140. Charman, D.J., Roe, H.M., Roland Gehrels, W., 2002. Modern distribution of saltmarsh testate amoebae: regional variability of zonation and response to environmental variables. Journal of Quaternary Science 17, 387-409. Horton, B.P., 1997. Quantification of the indicative meaning of a range of Holocene sea-level index points from the western North Sea, Department of Geography. University of Durham, Durham City, UK, p. 509. Horton, B.P., Corbett, R., Culver, S.J., Edwards, R.J., Hillier, C., 2006. Modern saltmarsh diatom distributions of the Outer Banks, North Carolina, and the development of a transfer function for high resolution reconstructions of sea level. Estuarine, Coastal and Shelf Science 69, 381-394. IOCAS (Institute of Oceanology, Chinese Academy of Sciences), 1985. Bohai Sea Geology. Science Press, Beijing, China. Madsen, A.T., Murray, A.S., Andersen, T.J., Pejrup, M., 2007. Temporal changes of accretion rates on an estuarine salt marsh during the late Holocene -Reflection of local sea level changes? The Wadden Sea, Denmark. Marine Geology 242, 221-233. Mauz, B., Hassler, U., 2000. Luminescence chronology of Late Pleistocene raised beaches in southern Italy: new data of relative sea-level changes. Marine Geology 170, 187-203. Yi, L., Yu, H.J., Ortiz, J.D., Xu, X.Y., Qiang, X.K., Huang, H.J., Shi, X., Deng, C.L., 2012. A reconstruction of late Pleistocene relative sea level in the south Bohai Sea, China, based on sediment grain-size analysis. Sedimentary Geology 281, 88-100. Zong, Y., Shennan, I., Combellick, R.A., Hamilton, S.L., Rutherford, M.M., 2003. Microfossil evidence for land movements associated with the AD 1964 Alaska earthquake. The Holocene 13, 7-20.

  15. Measurement of light scattering in deep sea

    NASA Astrophysics Data System (ADS)

    Maragos, N.; Balasi, K.; Domvoglou, T.; Kiskiras, I.; Lenis, D.; Maniatis, M.; Stavropoulos, G.

    2016-04-01

    The deep-sea neutrino telescope in the Mediterranean Sea, being prepared by the KM3NET collaboration, will contain thousands of optical sensors to readout. The accurate knowledge of the optical properties of deep-sea water is of great importance for the neutrino event reconstruction process. In this study we describe our progress in designing an experimental setup and studying a method to measure the parameters describing the absorption and scattering characteristics of deep-sea water. Three PMTs will be used to measure in situ the scattered light emitted from six laser diodes in three different wavelengths covering the Cherenkov radiation spectrum. The technique for the evaluation of the parameters is based on Monte Carlo simulations and our results show that we are able to determine these parameters with satisfying precision.

  16. Sea-level rise and coastal wetlands.

    PubMed

    Blankespoor, Brian; Dasgupta, Susmita; Laplante, Benoit

    2014-12-01

    This paper seeks to quantify the impact of a1-m sea-level rise on coastal wetlands in 86 developing countries and territories. It is found that approximately 68 % of coastal wetlands in these countries are at risk. A large percentage of this estimated loss is found in Europe and Central Asia, East Asia, and the Pacific, as well as in the Middle East and North Africa. A small number of countries will be severely affected. China and Vietnam(in East Asia and the Pacific), Libya and Egypt (in the Middle East and North Africa), and Romania and Ukraine (in Europe and Central Asia) will bear most losses. In economic terms, the loss of coastal wetlands is likely to exceed $703 million per year in 2000 US dollars. PMID:24659473

  17. The impact of groundwater depletion on spatial variations in sea level change during the past century

    NASA Astrophysics Data System (ADS)

    Veit, Emeline; Conrad, Clinton P.

    2016-04-01

    Continental groundwater loss during the past century has elevated sea level by up to ~25 mm. The mass unloading associated with this depletion locally uplifts Earth's solid surface and depresses the geoid, leading to slower relative sea level rise near areas of significant groundwater loss. We computed spatial variations in sea level using a model of the solid Earth's response to estimates of groundwater depletion during the past century and find large negative deviations of ~0.4 mm/yr along the coastlines of western North America and southern Asia. This approximately corresponds to the difference between rates of sea level rise measured by tide gauges in these regions since 1930 and average rates inferred from global reconstructions. Groundwater-induced regional variations in sea level can be larger than those due to postglacial rebound and interseismic deformation and should become increasingly important in the future as both groundwater depletion and sea level rise accelerate.

  18. An initial assessment of the genotoxic impact of the Sea Empress oil spill by the measurement of DNA adduct levels in the intertidal teleost Lipophrys pholis.

    PubMed

    Lyons, B P; Harvey, J S; Parry, J M

    1997-05-23

    The Sea Empress oil spill resulted in the release of vast quantities of potentially genotoxic contaminants into the coastal environment of the county of Pembrokeshire (UK). We are at present attempting to determine the potential genotoxic impact of the incident upon the native marine species of the area. Here we describe the levels of DNA adducts in specimens of the intertidal teleost, Lipophrys pholis, exposed to extensive oil extensive oil contamination as an indication of exposure to potential genotoxins. We detected elevated levels of adducts in L. pholis specimens from an area that underwent heavy oil contamination as compared to specimens from a clean reference area devoid of oil contamination. These preliminary studies indicated that the oil contamination induced DNA adducts in the L. pholis specimens, which could potentially cause genetic damage in this native marine species. Further studies are now required to assess the full extent of the genotoxic impact of the oil spill upon the Pembrokeshire area's native marine life. PMID:9186576

  19. Modeling future high-resolution dynamic sea level change

    NASA Astrophysics Data System (ADS)

    Brunnabend, Sandra-Esther; Dijkstra, Henk A.; Kliphuis, Michael A.; van Werkhoven, Ben; Bal, Henri E.; van Meersbergen, Maarten; Seinstra, Frank; Maassen, Jason

    2015-04-01

    Different studies have shown that resolving ocean eddies and representing boundary currents are of major importance when simulating changes in dynamic sea level on regional scale. Therefore, we use the strongly eddying global model version of the Parallel Ocean Program to simulate high-resolution future (up to the year 2100) sea surface height variations (SSH) under the SRES-A1B atmospheric forcing scenario. Results show dynamic sea level changes in the Southern Ocean that are caused by the southward shift in the westerly winds. The warming ocean (global mean sea surface temperature rises by about 2°C over the period 2000-2100) leads to a strong reduction of the Atlantic Meridional Overturning Circulation (AMOC). The magnitude of this reduction is affected by a feedback involving the heat transport to the sub-polar gyre region and evaporation over the North Atlantic region. The ocean circulation changes cause regional deviations from global mean sea level change in the North Atlantic. At coastal regions of eastern North America, dynamic sea level change leads to a positive deviation from global mean sea level change in the order of several decimeters. In the sub-polar gyre region a negative deviation from global mean sea level occurs. In the western North Atlantic, not only mean regional sea level is changed but also its variability, caused by shifted eddy pathways. This leads to a change in the frequency distribution of SSH anomalies, which has important consequences for regional sea level extremes.

  20. Global sea-level changes during the past century

    NASA Technical Reports Server (NTRS)

    Gornitz, Vivien; Lebedeff, Sergej

    1987-01-01

    A novel technique, initially developed for climate studies, is used to reevaluate the estimate of relative sea-level change over the past century. The technique produces a composite regional average sea-level curve from the tide-gage data of individual stations. The effects of glacioisostasy and long-term tectonism are accounted for using late Holocene sea-level indicators. Along the east coast of North America, an apparent maximum sea-level rise is detected in both tide-gage and late Holocene sea-level indicators between Chesapeake Bay and New Jersey. Sea-level changes in western North America reveal greater spatial variations than for the east coast, which can be related to more active tectonism in California and British Columbia and to strong localized isostatic rebound in Alaska.

  1. Ice volume and sea level during the last interglacial.

    PubMed

    Dutton, A; Lambeck, K

    2012-07-13

    During the last interglacial period, ~125,000 years ago, sea level was at least several meters higher than at present, with substantial variability observed for peak sea level at geographically diverse sites. Speculation that the West Antarctic ice sheet collapsed during the last interglacial period has drawn particular interest to understanding climate and ice-sheet dynamics during this time interval. We provide an internally consistent database of coral U-Th ages to assess last interglacial sea-level observations in the context of isostatic modeling and stratigraphic evidence. These data indicate that global (eustatic) sea level peaked 5.5 to 9 meters above present sea level, requiring smaller ice sheets in both Greenland and Antarctica relative to today and indicating strong sea-level sensitivity to small changes in radiative forcing. PMID:22798610

  2. Timescales for detecting a significant acceleration in sea level rise.

    PubMed

    Haigh, Ivan D; Wahl, Thomas; Rohling, Eelco J; Price, René M; Pattiaratchi, Charitha B; Calafat, Francisco M; Dangendorf, Sönke

    2014-01-01

    There is observational evidence that global sea level is rising and there is concern that the rate of rise will increase, significantly threatening coastal communities. However, considerable debate remains as to whether the rate of sea level rise is currently increasing and, if so, by how much. Here we provide new insights into sea level accelerations by applying the main methods that have been used previously to search for accelerations in historical data, to identify the timings (with uncertainties) at which accelerations might first be recognized in a statistically significant manner (if not apparent already) in sea level records that we have artificially extended to 2100. We find that the most important approach to earliest possible detection of a significant sea level acceleration lies in improved understanding (and subsequent removal) of interannual to multidecadal variability in sea level records. PMID:24728012

  3. Timescales for detecting a significant acceleration in sea level rise

    PubMed Central

    Haigh, Ivan D.; Wahl, Thomas; Rohling, Eelco J.; Price, René M.; Pattiaratchi, Charitha B.; Calafat, Francisco M.; Dangendorf, Sönke

    2014-01-01

    There is observational evidence that global sea level is rising and there is concern that the rate of rise will increase, significantly threatening coastal communities. However, considerable debate remains as to whether the rate of sea level rise is currently increasing and, if so, by how much. Here we provide new insights into sea level accelerations by applying the main methods that have been used previously to search for accelerations in historical data, to identify the timings (with uncertainties) at which accelerations might first be recognized in a statistically significant manner (if not apparent already) in sea level records that we have artificially extended to 2100. We find that the most important approach to earliest possible detection of a significant sea level acceleration lies in improved understanding (and subsequent removal) of interannual to multidecadal variability in sea level records. PMID:24728012

  4. Greenland's Contribution to Early 20th Century Sea-Level Rise Determined by Sea-Level Fingerprinting

    NASA Astrophysics Data System (ADS)

    Gehrels, W. R.; Milne, G. A.; Callard, S. L.; Moss, P. T.; Marshall, W. A.; Morrison, B. V.; Woodworth, P. L.

    2010-12-01

    Instrumental observations indicate that sea-level rise has accelerated compared to average late Holocene trends reconstructed by geological methods. In proxy sea-level reconstructions from North Atlantic salt marshes this inflexion has been dated to the late 19th century or early 20th century. This paper documents inflexions in recent sea-level records from salt marshes in the Southwest Pacific. A new record from Tasmania was dated by high-precision AMS14C, ‘bomb-spike’ AMS14C, 137Cs, 210Pb, stable Pb isotopic ratios, trace metal and pollen analyses. Sea-level positions were determined by foraminiferal analyses. The change in the rate of sea-level rise around 1900, recorded in Tasmania and southern New Zealand, is 2.5 to 3 mm/yr and is significantly larger than in North Atlantic sea-level records (Fig. 1). This difference in the character of the onset of 20th century sea-level rise is potentially highly significant, because sea-level ‘fingerprint’ theory predicts that polar ice melt produces faster rates of sea-level rise in the opposite hemisphere. A more rapid sea-level rise in the Southwest Pacific compared to the North Atlantic therefore could point at the Greenland Ice Sheet as an important melt source for the global sea-level acceleration at the turn of the 20th century. Preliminary calculations, which include allowances for steric, small glacier and Antarctic contributions, indicate that Greenland may have contributed at least ~0.5 mm/yr to the acceleration. More robust considerations of steric changes and ocean dynamics are required to test this hypothesis. Fig. 1. Schematic compilation of proxy sea-level records from salt marshes (green) and long tide-gauge records (red) showing variability in the magnitude of the 19th-20th century sea-level acceleration.

  5. The Future of GLOSS Sea Level Data Archaeology

    NASA Astrophysics Data System (ADS)

    Jevrejeva, S.; Bradshaw, E.; Tamisiea, M. E.; Aarup, T.

    2014-12-01

    Long term climate records are rare, consisting of unique and unrepeatable measurements. However, data do exist in analogue form in archives, libraries and other repositories around the world. The Global Sea Level Observing System (GLOSS) Group of Experts aims to provide advice on locating hidden tide gauge data, scanning and digitising records and quality controlling the resulting data. Long sea level data time series are used in Intergovernmental Panel on Climate Change (IPCC) assessment reports and climate studies, in oceanography to study changes in ocean currents, tides and storm surges, in geodesy to establish national datum and in geography and geology to monitor coastal land movement. GLOSS has carried out a number of data archaeology activities over the past decade, which have mainly involved sending member organisations questionnaires on their repositories. The Group of Experts is now looking at future developments in sea level data archaeology and how new technologies coming on line could be used by member organisations to make data digitisation and transcription more efficient. Analogue tide data comes in two forms charts, which record the continuous measurements made by an instrument, usually via a pen trace on paper ledgers containing written values of observations The GLOSS data archaeology web pages will provide a list of software that member organisations have reported to be suitable for the automatic digitisation of tide gauge charts. Transcribing of ledgers has so far proved more labour intensive and is usually conducted by people entering numbers by hand. GLOSS is exploring using Citizen Science techniques, such as those employed by the Old Weather project, to improve the efficiency of transcribing ledgers. The Group of Experts is also looking at recent advances in Handwritten Text Recognition (HTR) technology, which mainly relies on patterns in the written word, but could be adapted to work with the patterns inherent in sea level data.

  6. Global sea level trend in the past century

    NASA Technical Reports Server (NTRS)

    Gornitz, V.; Lebedeff, S.; Hansen, J.

    1982-01-01

    Data derived from tide-gauge stations throughout the world indicate that the mean sea level rose by about 12 centimeters in the past century. The sea level change has a high correlation with the trend of global surface air temperature. A large part of the sea level rise can be accounted for in terms of the thermal expansion of the upper layers of the ocean. The results also represent weak indirect evidence for a net melting of the continental ice sheets.

  7. Measuring the sea ice floe size distribution

    NASA Technical Reports Server (NTRS)

    Rothrock, D. A.; Thorndike, A. S.

    1984-01-01

    The sea ice covering the Arctic Ocean is broken into distinct pieces,called floes. In the summer, these floes, which have diameters ranging up to 100 km, are separated from each other by a region of open water. In the winter, floes still exist, but they are less easily identified. An understanding of the geometry of the ice pack is of interest for a number of practical applications associated with transportation in ice-covered seas and with the design of offshore structures intended to survive in the presence of ice. The present investigation has the objective to clarify ideas about floe sizes and to propose techniques for measuring them. Measurements are presented with the primary aim to illustrate points of technique or approach. A preliminary discussion of the floe size distribution of sea ice is devoted to questions of definition and of measurement.

  8. Monitoring sea level fluctuation in South Aegean

    NASA Astrophysics Data System (ADS)

    Zacharis, Vangelis; Paradissis, Demitris; Drakatos, George; Marinou, Aggeliki; Melis, Nicolaos; Anastasiou, Demitris; Alatza, Stavroula; Papanikolaou, Xanthos

    2015-04-01

    The complexity of the geological setting of the South Aegean is well-known, among the scientific community. The subduction zone coupled with the latest unrest of the Santorini volcano, as well as the particular morphology of the earth's surface and seabed pose a poorly understood source of tsunami hazard. A sparse network of tide gauges that operate in the area for varying periods of time is strengthened by the establishment of new sensors at carefully selected locations, by the Institute of Geodynamics of the National Observatory of Athens, and the Dionyssos Satellite Observatory and the Laboratory of Higher Geodesy of the National Technical University of Athens. These new instruments, aided by a rather dense network of GNSS receivers, provide a more concrete basis for the development, testing and evaluation of a near real-time model of the sea level changes in the area. Moreover, integration with various other sensors allows to understand and assess the level of tsunami risk in the area.

  9. Coherent sea level variation in and around the Sea of Okhotsk

    NASA Astrophysics Data System (ADS)

    Nakanowatari, Takuya; Ohshima, Kay I.

    2014-08-01

    We investigated the seasonal and interannual variations of the sea level in and around the Sea of Okhotsk and their causes, based on tide gauge and satellite altimeter data. The sea level all along the coastal region of the Sea of Okhotsk is found to be dominated by the seasonal variation with a maximum in winter and a minimum in summer, which cannot be explained by the annual cycle of atmospheric heat flux and pressure. This sea level variation appears to reflect ocean current variations. Both the Arrested Topographic Waves (ATWs) caused by alongshore wind stress and the Sverdrup transport by wind stress curl show corresponding seasonal variations. Seasonal amplitude of the sea level is relatively large along Sakhalin Island with a tendency of a larger amplitude toward the south. This meridional dependence is consistent with the ATWs, but not with the Sverdrup transport in the Sea of Okhotsk. Seasonal variation of the geostrophic current velocity expected from the sea level variation is comparable to that of the observed nearshore current and is consistent with the theoretical ATW transport. It is also revealed that, on an interannual timescale, the wintertime sea level fluctuates quite coherently all around the Sea of Okhotsk and further along the East Kamchatka and Oyashio coasts in the North Pacific. The altimeter data clearly show that this coherent sea level variation is trapped over the coastal and continental shelf regions with depths shallower than 1000 m. The wintertime sea levels have a higher correlation with the ATW transport than with the Sverdrup transport in the Sea of Okhotsk and the upstream East Kamchatka coast. All these suggest that the interannual sea level variation along the coastal and shelf regions in winter, as well as the seasonal variation, is mainly caused by the ATWs (coastal trapped current forced by the alongshore wind stress). The wintertime Sverdrup transport, raised by the previous studies, is the secondary contributor to these variations.

  10. The Sensitivity of Coastal Cliffs to Changes in Sea Level

    NASA Astrophysics Data System (ADS)

    Rosser, N.; Lim, M.; Petley, D.

    2007-12-01

    The impact of waves upon coastal cliffs is a significant control on erosion and subsequent cliff retreat. It is widely anticipated that climatically-driven sea-level rise will result in an increase in the rate of erosion, and thus the retreat, of coastal cliffs. Quantifying the changes in the rate of coastal erosion remains problematic, primarily due to the difficulty of collecting high-precision and high-frequency monitoring data on both cliff change and the variations in environmental conditions at the coast. In the UK, local authorities now have to produce a "Shoreline Management Plan" (SMP), indicating how the coastline will be managed for the future. This requires the estimation of rates of coastal retreat over the next century, making the impact of sea-level change a critical consideration. This study presents the results from a three year monitoring survey of a section of near-vertical coastal cliffs in north-east England. Data have been collected using a high-resolution terrestrial laser scanner to obtain cliff surfaces. Analysis of successive 3D cliff models is used to derive sequential change, from which the precise nature, geometry and rate of retreat can be measured. In parallel, data has been collected on the micro-seismic impact of waves onto the cliff to gain a direct measure of the delivery of energy at any given sea-level, rather than using a function of wave and tide gauge records. The coastline studied has a significant tidal range, in excess of 6 m, in addition to a large seasonal variability in mean tide heights, allowing a range of sea-level conditions to be assessed. For comparison weather, tide and wave monitoring has been undertaken. The results suggest a close link between the magnitude and frequency of wave impact and the loss of material from the cliff face. Marked changes in wave impact are apparent as the tide level fluctuates on an inter-monthly and inter-annual basis. Thresholds are identified which appear to reflect discrete changes in wave energy delivery as tidal level rises, possibly reflecting critical inundation depths and wave propagation up onto the cliff face. The cliff monitoring data show a similar sensitivity with a marked increase in absolute volumes of material loss, the location of these losses on the cliff face and the resulting effective rate of cliff face retreat. The results demonstrate the sensitivity of the cliffs and the short term variability in response. The study provides significant insights into both the likely future retreat of cliffs in response to climate change and perhaps more importantly the nature with which cliffs accommodate and respond to sea-level changes.

  11. Evolution of a Coupled Marine Ice Sheet - Sea Level Model

    NASA Astrophysics Data System (ADS)

    Gomez, N.; Pollard, D.; Mitrovica, J. X.; Huybers, P.; Clark, P. U.

    2012-04-01

    An instability mechanism is widely predicted for marine ice sheets resting upon reversed bed slopes whereby ice-sheet thinning or rising sea level is thought to lead to irreversible retreat of the grounding line. Previous analyses of marine ice-sheet stability have considered the influence of a sea-level perturbation on ice-sheet stability by assuming a geographically uniform, or eustatic, change in sea level. However, gravitational, deformational and rotational effects associated with changes in the volume of grounded ice lead to markedly non-uniform spatial patterns of sea-level change. In particular, a gravitationally self-consistent sea-level theory predicts a sea-level fall in the vicinity of a shrinking ice sheet that is an order of magnitude greater amplitude than the sea-level rise that would be predicted assuming eustasy. We highlight the stabilizing influence of local sea-level changes on marine ice sheets by incorporating gravitationally self-consistent sea-level changes into a steady state model of ice sheet stability (Gomez et. al., Nature Geoscience, 2010). In addition, we develop a dynamic coupled ice sheet - sea level model to consider the impact of this stabilizing mechanism on the timescale of ice sheet retreat. The coupled system combines a sea-level model valid for a self-gravitating, viscoelastically deforming Earth to a 1D, dynamic marine ice sheet-shelf model. The evolution of the coupled model is explored for a suite of simulations in which we vary the bed slope and the forcing that initiates retreat. We find that the sea-level fall at the grounding line associated with a retreating ice sheet acts to slow the retreat; in simulations with shallow reversed bed slopes and/or small initial forcing, the drop in sea level can be sufficient to halt the retreat. The rate of sea-level change at the grounding line has an elastic component due to ongoing changes in ice-sheet geometry, and a viscous component due to past ice and ocean load changes. When the ice-sheet model is forced from steady state, then on short timescales (< ~500 years) viscous effects may be ignored and grounding-line migration at a given time will depend on the local bedrock topography and on contemporaneous sea-level changes driven by ongoing ice-sheet mass flux. On longer timescales, an accurate assessment of the present stability of a marine ice sheet requires knowledge of its past evolution. We end with a discussion of the first results of simulations in which post-glacial sea-level physics is coupled to a 3D, dynamic model of the Antarctic Ice Sheet.

  12. The Sea Level Conundrum: Insights From Paleo Studies

    NASA Astrophysics Data System (ADS)

    Siddall, Mark; Clark, Peter; Thompson, Bill; Waelbroeck, Claire; Gregory, Jonathan; Stocker, Thomas

    2009-03-01

    Empirical Constraints on Future Sea Level Rise; Bern, Switzerland, 25-29 August 2008; Eustatic sea level (ESL) rise during the 21st century is perhaps the greatest threat from climate change, but its magnitude is contested. Geological records identify examples of nonlinear ice sheet response to climate forcing, suggesting a strategy for refining estimates of 21st-century sea level change. In August 2008, Past Global Changes (PAGES), International Marine Past Global Change Study (IMAGES), and the University of Bern cosponsored a workshop to address this possibility. The workshop highlighted several ways that paleoceanography studies can place limits on future sea level rise, and these are enlarged upon here.

  13. Ice-sheet and sea-level changes.

    PubMed

    Alley, Richard B; Clark, Peter U; Huybrechts, Philippe; Joughin, Ian

    2005-10-21

    Future sea-level rise is an important issue related to the continuing buildup of atmospheric greenhouse gas concentrations. The Greenland and Antarctic ice sheets, with the potential to raise sea level approximately 70 meters if completely melted, dominate uncertainties in projected sea-level change. Freshwater fluxes from these ice sheets also may affect oceanic circulation, contributing to climate change. Observational and modeling advances have reduced many uncertainties related to ice-sheet behavior, but recently detected, rapid ice-marginal changes contributing to sea-level rise may indicate greater ice-sheet sensitivity to warming than previously considered. PMID:16239468

  14. Demographic responses to sea level rise in California

    SciTech Connect

    Constable, A.; Van Arsdol, M.D. Jr.; Sherman, D.J.; Wang, J.; McMullin-Messier, P.A.; Rollin, L.

    1996-12-31

    Human consequences of sea level rise in California coastal counties reflect increasing population densities. Populations of coastal counties potentially affected by sea level rise are projected to increase from 26.2 million persons in 1990 to 63.3 million persons in 2040. Urbanization dominates Los Angeles and the South Coast and San Francisco Bay and Delta regions. California shoreline populations subject to potential disruption impacts of sea level rise are increasing rapidly. Enhanced risk zones for sea level rise are specified for the Oxnard Plain of Ventura County on the south coast of California. Four separate sea level rise scenarios are considered: (1) low (sea level rise only); (2) moderate (adding erosion); (3) high (adding erosion and storm surges); and (4) a maximum case, a 3 m enhanced risk zone. Population impacts are outlined for the 3 m zone. More serious impacts from storm surges are expected than from sea level rise and erosion. Stakeholders who support or oppose policies which may expose populations to sea level rise include energy, commercial, financial, industrial, public agency, private interest and governmental organizations. These organizations respond to extreme events from differing positions. Vested interests determine the degree of mitigation employed by stakeholders to defer impacts of sea level rise.

  15. Mangrove Sedimentation and Response to Relative Sea-Level Rise.

    PubMed

    Woodroffe, C D; Rogers, K; McKee, K L; Lovelock, C E; Mendelssohn, I A; Saintilan, N

    2016-01-01

    Mangroves occur on upper intertidal shorelines in the tropics and subtropics. Complex hydrodynamic and salinity conditions, related primarily to elevation and hydroperiod, influence mangrove distributions; this review considers how these distributions change over time. Accumulation rates of allochthonous and autochthonous sediment, both inorganic and organic, vary between and within different settings. Abundant terrigenous sediment can form dynamic mudbanks, and tides redistribute sediment, contrasting with mangrove peat in sediment-starved carbonate settings. Sediments underlying mangroves sequester carbon but also contain paleoenvironmental records of adjustments to past sea-level changes. Radiometric dating indicates long-term sedimentation, whereas measurements made using surface elevation tables and marker horizons provide shorter perspectives, indicating shallow subsurface processes of root growth and substrate autocompaction. Many tropical deltas also experience deep subsidence, which augments relative sea-level rise. The persistence of mangroves implies an ability to cope with moderately high rates of relative sea-level rise. However, many human pressures threaten mangroves, resulting in a continuing decline in their extent throughout the tropics. PMID:26407146

  16. Mangrove Sedimentation and Response to Relative Sea-Level Rise

    NASA Astrophysics Data System (ADS)

    Woodroffe, C. D.; Rogers, K.; McKee, K. L.; Lovelock, C. E.; Mendelssohn, I. A.; Saintilan, N.

    2016-01-01

    Mangroves occur on upper intertidal shorelines in the tropics and subtropics. Complex hydrodynamic and salinity conditions, related primarily to elevation and hydroperiod, influence mangrove distributions; this review considers how these distributions change over time. Accumulation rates of allochthonous and autochthonous sediment, both inorganic and organic, vary between and within different settings. Abundant terrigenous sediment can form dynamic mudbanks, and tides redistribute sediment, contrasting with mangrove peat in sediment-starved carbonate settings. Sediments underlying mangroves sequester carbon but also contain paleoenvironmental records of adjustments to past sea-level changes. Radiometric dating indicates long-term sedimentation, whereas measurements made using surface elevation tables and marker horizons provide shorter perspectives, indicating shallow subsurface processes of root growth and substrate autocompaction. Many tropical deltas also experience deep subsidence, which augments relative sea-level rise. The persistence of mangroves implies an ability to cope with moderately high rates of relative sea-level rise. However, many human pressures threaten mangroves, resulting in a continuing decline in their extent throughout the tropics. *

  17. Mangrove sedimentation and response to relative sea-level rise

    USGS Publications Warehouse

    Woodroffe, CD; Rogers, K.; Mckee, Karen L.; Lovelock, CE; Mendelssohn, IA; Saintilan, N.

    2016-01-01

    Mangroves occur on upper intertidal shorelines in the tropics and subtropics. Complex hydrodynamic and salinity conditions influence mangrove distributions, primarily related to elevation and hydroperiod; this review considers how these adjust through time. Accumulation rates of allochthonous and autochthonous sediment, both inorganic and organic, vary between and within different settings. Abundant terrigenous sediment can form dynamic mudbanks; tides redistribute sediment, contrasting with mangrove peat in sediment-starved carbonate settings. Sediments underlying mangroves sequester carbon, but also contain paleoenvironmental records of adjustments to past sea-level changes. Radiometric dating indicates long-term sedimentation, whereas Surface Elevation Table-Marker Horizon measurements (SET-MH) provide shorter perspectives, indicating shallow subsurface processes of root growth and substrate autocompaction. Many tropical deltas also experience deep subsidence, which augments relative sea-level rise. The persistence of mangroves implies an ability to cope with moderately high rates of relative sea-level rise. However, many human pressures threaten mangroves, resulting in continuing decline in their extent throughout the tropics.

  18. Detecting anthropogenic footprints in sea level rise.

    PubMed

    Dangendorf, Sönke; Marcos, Marta; Müller, Alfred; Zorita, Eduardo; Riva, Riccardo; Berk, Kevin; Jensen, Jürgen

    2015-01-01

    While there is scientific consensus that global and local mean sea level (GMSL and LMSL) has risen since the late nineteenth century, the relative contribution of natural and anthropogenic forcing remains unclear. Here we provide a probabilistic upper range of long-term persistent natural GMSL/LMSL variability (P=0.99), which in turn, determines the minimum/maximum anthropogenic contribution since 1900. To account for different spectral characteristics of various contributing processes, we separate LMSL into two components: a slowly varying volumetric component and a more rapidly changing atmospheric component. We find that the persistence of slow natural volumetric changes is underestimated in records where transient atmospheric processes dominate the spectrum. This leads to a local underestimation of possible natural trends of up to ∼1 mm per year erroneously enhancing the significance of anthropogenic footprints. The GMSL, however, remains unaffected by such biases. On the basis of a model assessment of the separate components, we conclude that it is virtually certain (P=0.99) that at least 45% of the observed increase in GMSL is of anthropogenic origin. PMID:26220773

  19. Detecting anthropogenic footprints in sea level rise

    PubMed Central

    Dangendorf, Sönke; Marcos, Marta; Müller, Alfred; Zorita, Eduardo; Riva, Riccardo; Berk, Kevin; Jensen, Jürgen

    2015-01-01

    While there is scientific consensus that global and local mean sea level (GMSL and LMSL) has risen since the late nineteenth century, the relative contribution of natural and anthropogenic forcing remains unclear. Here we provide a probabilistic upper range of long-term persistent natural GMSL/LMSL variability (P=0.99), which in turn, determines the minimum/maximum anthropogenic contribution since 1900. To account for different spectral characteristics of various contributing processes, we separate LMSL into two components: a slowly varying volumetric component and a more rapidly changing atmospheric component. We find that the persistence of slow natural volumetric changes is underestimated in records where transient atmospheric processes dominate the spectrum. This leads to a local underestimation of possible natural trends of up to ∼1 mm per year erroneously enhancing the significance of anthropogenic footprints. The GMSL, however, remains unaffected by such biases. On the basis of a model assessment of the separate components, we conclude that it is virtually certain (P=0.99) that at least 45% of the observed increase in GMSL is of anthropogenic origin. PMID:26220773

  20. Stochastic secular trends in sea level rise

    NASA Astrophysics Data System (ADS)

    Ocaña, Victor; Zorita, Eduardo; Heimbach, Patrick

    2016-04-01

    Global mean sea level (GMSL) has been rising since (at least) the nineteenth century and the rate of rise may be increasing. Several studies that attempt to explain the long-term trend of GMSL during the instrumental record share the common assumption that this trend is deterministic in nature and different from natural variations. Here we show that the trend can alternatively be explained, at least in part, as being caused by random variations within the coupled ocean-atmosphere-cryosphere system, and hence not having a deterministic origin. These random trends, which add to externally forced changes (e.g., through anthropogenic climate change), are a consequence of the integrated character of GMSL, which is the cumulative addition of temporal contributions that exhibit random character, and whose integration results in GMSL variations with persistence on decadal-centennial time scales. The generation of trends by integration of random stationary noise (i.e., even in a constant climate) is a robust and fundamental feature of stochastically forced systems with memory. The integrated character of GMSL results in an intrinsic difficulty in distinguishing internal from externally forced trends.

  1. Dynamic response of the Black Sea elevation to intraseasonal fluctuations of the Mediterranean sea level

    NASA Astrophysics Data System (ADS)

    Volkov, Denis L.; Johns, William E.; Belonenko, Tatyana V.

    2016-01-01

    Response of the Black Sea elevation to intraseasonal sea level changes in the Mediterranean is studied using satellite altimetry data and a linear analytical model. Satellite observations show that the nonseasonal sea level in the Black Sea (η1) is coherent with that in the Aegean and Marmara Seas (η0) but lags behind them by 10-40 days at subannual periods. The observed time lag is mainly due to friction that constrains the exchange through the Bosphorus Strait. Using realistic friction and characteristic η0 forcing in the model, we find that the amplitude of η1 reaches the amplitude of η0 at about 1 year period, and the time lag increases from 10 to 22 days at periods 50-250 days. Freshwater fluxes, atmospheric pressure, and to a smaller extent the along-strait wind also influence the Black Sea elevation, but sea level fluctuations in the Mediterranean appear to be the dominant forcing mechanism.

  2. Numerical study of the Azov Sea level seiche oscillations

    NASA Astrophysics Data System (ADS)

    Matishov, G. G.; Inzhebeikin, Yu. I.

    2009-08-01

    Seiche oscillations of the Azov Sea level are studied on the basis of the developed two-dimensional numerical hydrodynamic model grounded on the shallow water theory and recent data on the morphometric characteristics of the Sea of Azov. Frequency and spatial characteristics of the first five modes corresponding to seiche oscillations of the Azov Sea level are computed. It is shown that the frequency and spatial characteristics of the first five modes obtained for the Sea of Azov level changes correspond to seiche oscillations. The calculated parameters are compared with the field observations, which show their realistic character.

  3. 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.

  4. A search for scale in sea-level studies

    USGS Publications Warehouse

    Larsen, C.E.; Clark, I.

    2006-01-01

    Many researchers assume a proportional relationship among the atmospheric CO2 concentration, temperature, and sea level. Thus, the rate of sea-level rise should increase in concert with the documented exponential increase in CO2. Although sea surface temperature has increased in places over the past century and short-term sea level rose abruptly during the 1990s, it is difficult to demonstrate a proportional relationship using existing geologic or historic records. Tide gauge records in the United States cover too short a time interval to verify acceleration in the rate of sea-level rise, although multicentury tide gauge and staff records from the Netherlands and Sweden suggest a mid-19th-century acceleration in sea-level rise. Reconstructions of sea-level changes for the past 1000 years derived using benthic foraminifer data from salt marshes along the East Coast of the United States suggest an increased rate of relative sea-level rise beginning in the 1600s. Geologic records of relative sea-level rise for the past 6000 years are available for several sites along the US East Coast from 14C-dated basal peat below salt marshes and estuarine sediments. When these three scales of sea-level variation are integrated, adjusted for postglacial isostatic movement, and replotted, the range of variation in sea level suggested by basal peat ages is within ??1 meter of the long-term trend. The reconstruction from Long Island Sound data shows a linear rise in sea level beginning in the mid-1600s at a rate consistent with the historic record of mean high water. Long-term tide gauge records from Europe and North America show similar trends since the mid-19th century. There is no clear proportional exponential increase in the rate of sea-level rise. If proportionality exists among sea level, atmospheric CO2, and temperature, there may be a significant time lag before an anthropogenic increase in the rate of sea-level rise occurs.

  5. Sea-level variability in the Mediterranean Sea from altimetry and tide gauges

    NASA Astrophysics Data System (ADS)

    Bonaduce, A.; Pinardi, N.; Oddo, P.; Spada, G.; Larnicol, G.

    2016-02-01

    Sea-level variability in the Mediterranean Sea was investigated by means of in-situ (tide-gauge) and satellite altimetry data over a period spanning two decades (from 1993 to 2012). The paper details the sea-level variations during this time period retrieved from the two data sets. Mean sea-level (MSL) estimates obtained from tide-gauge data showed root mean square differences (RMSDs) in the order of 40-50 % of the variance of the MSL signal estimated from satellite altimetry data, with a dependency on the number and quality of the in-situ data considered. Considering the individual time-series, the results showed that coastal tide-gauge and satellite sea-level signals are comparable, with RMSDs that range between 2.5 and 5 cm and correlation coefficients up to the order of 0.8. A coherence analysis and power spectra comparison showed that two signals have a very similar energetic content at semi-annual temporal scales and below, while a phase drift was observed at higher frequencies. Positive sea-level linear trends for the analysis period were estimated for both the mean sea-level and the coastal stations. From 1993 to 2012, the mean sea-level trend (2.44± 0.5 mm year^{-1} ) was found to be affected by the positive anomalies of 2010 and 2011, which were observed in all the cases analysed and were mainly distributed in the eastern part of the basin. Ensemble empirical mode decomposition showed that these events were related to the processes that have dominant periodicities of ˜ 10 years, and positive residual sea-level trend were generally observed in both data-sets. In terms of mean sea-level trends, a significant positive sea-level trend (> 95 %) in the Mediterranean Sea was found on the basis of at least 15 years of data.

  6. Does Sea Level Change when a Floating Iceberg Melts?

    ERIC Educational Resources Information Center

    Lan, Boon Leong

    2010-01-01

    On the answer page to a recent "Figuring Physics" question, the cute mouse asks another question: "Does the [sea] water level change if the iceberg melts?" The conventional answer is "no." However, in this paper I will show through a simple analysis involving Archimedes' principle that the sea level will rise. The analysis shows the wrong…

  7. Upper limit for sea level projections by 2100

    NASA Astrophysics Data System (ADS)

    Jevrejeva, S.; Grinsted, A.; Moore, J. C.

    2014-10-01

    We construct the probability density function of global sea level at 2100, estimating that sea level rises larger than 180 cm are less than 5% probable. An upper limit for global sea level rise of 190 cm is assembled by summing the highest estimates of individual sea level rise components simulated by process based models with the RCP8.5 scenario. The agreement between the methods may suggest more confidence than is warranted since large uncertainties remain due to the lack of scenario-dependent projections from ice sheet dynamical models, particularly for mass loss from marine-based fast flowing outlet glaciers in Antarctica. This leads to an intrinsically hard to quantify fat tail in the probability distribution for global mean sea level rise. Thus our low probability upper limit of sea level projections cannot be considered definitive. Nevertheless, our upper limit of 180 cm for sea level rise by 2100 is based on both expert opinion and process studies and hence indicates that other lines of evidence are needed to justify a larger sea level rise this century.

  8. Future extreme sea level seesaws in the tropical Pacific.

    PubMed

    Widlansky, Matthew J; Timmermann, Axel; Cai, Wenju

    2015-09-01

    Global mean sea levels are projected to gradually rise in response to greenhouse warming. However, on shorter time scales, modes of natural climate variability in the Pacific, such as the El Niño-Southern Oscillation (ENSO), can affect regional sea level variability and extremes, with considerable impacts on coastal ecosystems and island nations. How these shorter-term sea level fluctuations will change in association with a projected increase in extreme El Niño and its atmospheric variability remains unknown. Using present-generation coupled climate models forced with increasing greenhouse gas concentrations and subtracting the effect of global mean sea level rise, we find that climate change will enhance El Niño-related sea level extremes, especially in the tropical southwestern Pacific, where very low sea level events, locally known as Taimasa, are projected to double in occurrence. Additionally, and throughout the tropical Pacific, prolonged interannual sea level inundations are also found to become more likely with greenhouse warming and increased frequency of extreme La Niña events, thus exacerbating the coastal impacts of the projected global mean sea level rise. PMID:26601272

  9. Estuaries May Face Increased Parasitism as Sea Levels Rise

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-12-01

    Invertebrates in estuaries could be at a greater risk of parasitism as climate change causes sea levels to rise. A new paper published 8 December in Proceedings of the National Academy of Sciences of the United States of America (doi:10.1073/pnas.1416747111) describes how rapid sea level rise in the Holocene affected the population of parasitic flatworms called trematodes.

  10. Future Extreme Sea Level Variability in the Tropical Pacific

    NASA Astrophysics Data System (ADS)

    Widlansky, M. J.; Timmermann, A.; Stuecker, M. F.; McGregor, S.; Cai, W.; Chikamoto, Y.

    2014-12-01

    During strong El Niño events, sea level drops around tropical western Pacific islands by up to 20-30 cm. Such extreme events (referred to in Samoa as 'taimasa') expose shallow reefs, thereby damaging associated coastal ecosystems and contributing to the formation of 'flat topped coral heads' often referred to as microatolls. We show that during the termination of strong El Niño events, a southward movement of weak trade winds prolongs extreme low sea levels in the southwestern Pacific. Whereas future sea levels are projected to gradually rise, recent modeling evidence suggests that the frequency of strong El Niño events (which alter local trade winds and sea level) is very likely to increase with greenhouse warming. Such changes could exacerbate El Niño-related sea level drops, especially in the tropical southwestern Pacific. Using present-generation coupled climate models forced with increasing greenhouse-gas concentrations, we assess how the interplay between global mean sea level rise, on one hand, and more frequent interannual sea level drops, on the other, will affect future coastal sea levels in the tropical Pacific.

  11. Late Holocene sea-level change in Arctic Norway

    NASA Astrophysics Data System (ADS)

    Barnett, Robert L.; Gehrels, W. Roland; Charman, Dan J.; Saher, Margot H.; Marshall, William A.

    2015-01-01

    Relative sea-level data from the pre-industrial era are required for validating geophysical models of glacio-isostatic adjustment as well as for testing models used to make sea-level predictions based on future climate change scenarios. We present the first late Holocene (past ˜3300 years) relative sea-level reconstruction for northwestern Norway based on investigations in South Hinnøya in the Vesterålen - Lofoton archipelago. Sea-level changes are reconstructed from analyses of salt-marsh and estuarine sediments and the micro-organisms (foraminifera and testate amoebae) preserved within. The 'indicative meaning' of the microfauna is established from their modern distributions. Records are dated by radiocarbon, 201Pb, 137Cs and chemostratigraphical analyses. Our results show a continuous relative sea-level decline of 0.7-0.9 mm yr-1 for South Hinnøya during the late Holocene. The reconstruction extends the relative sea-level trend recorded by local tide gauge data which is only available for the past ˜25 years. Our reconstruction demonstrates that existing models of shoreline elevations and GIA overpredict sea-level positions during the late Holocene. We suggest that models might be adjusted in order to reconcile modelled and reconstructed sea-level changes and ultimately improve understanding of GIA in Fennoscandia.

  12. Future extreme sea level seesaws in the tropical Pacific

    PubMed Central

    Widlansky, Matthew J.; Timmermann, Axel; Cai, Wenju

    2015-01-01

    Global mean sea levels are projected to gradually rise in response to greenhouse warming. However, on shorter time scales, modes of natural climate variability in the Pacific, such as the El Niño–Southern Oscillation (ENSO), can affect regional sea level variability and extremes, with considerable impacts on coastal ecosystems and island nations. How these shorter-term sea level fluctuations will change in association with a projected increase in extreme El Niño and its atmospheric variability remains unknown. Using present-generation coupled climate models forced with increasing greenhouse gas concentrations and subtracting the effect of global mean sea level rise, we find that climate change will enhance El Niño–related sea level extremes, especially in the tropical southwestern Pacific, where very low sea level events, locally known as Taimasa, are projected to double in occurrence. Additionally, and throughout the tropical Pacific, prolonged interannual sea level inundations are also found to become more likely with greenhouse warming and increased frequency of extreme La Niña events, thus exacerbating the coastal impacts of the projected global mean sea level rise. PMID:26601272

  13. Does Sea Level Change when a Floating Iceberg Melts?

    ERIC Educational Resources Information Center

    Lan, Boon Leong

    2010-01-01

    On the answer page to a recent "Figuring Physics" question, the cute mouse asks another question: "Does the [sea] water level change if the iceberg melts?" The conventional answer is "no." However, in this paper I will show through a simple analysis involving Archimedes' principle that the sea level will rise. The analysis shows the wrong

  14. Evolution of a Coupled Marine Ice Sheet - Sea Level Model

    NASA Astrophysics Data System (ADS)

    Gomez, N.; Pollard, D.; Mitrovica, J. X.; Huybers, P.; Clark, P. U.

    2011-12-01

    An instability mechanism is widely predicted for marine ice sheets resting upon reversed bed slopes. In this case, ice-sheet thinning or rising sea level is thought to lead to irreversible retreat of the grounding line. Previous analyses of marine ice-sheet stability have considered the influence of a sea-level perturbation on ice-sheet stability by assuming a geographically uniform, or eustatic, change in sea level. However, gravitational and deformational effects associated with changes in the volume of grounded ice lead to markedly non-uniform spatial patterns of sea-level change. In particular, a gravitationally self-consistent sea-level theory predicts a near-field sea-level change of opposite sign, and an order of magnitude greater amplitude, than would be predicted assuming eustasy. In recent work (Gomez et. al., Nature Geoscience, 2010), we highlighted the potential importance of this stabilizing sea-level mechanism by incorporating gravitationally self-consistent sea-level changes into a steady state ice sheet model. We extend this earlier analysis to investigate the influence of this stabilization mechanism on the timescale of ice-sheet retreat by coupling a sea-level model valid for a self-gravitating, viscoelastically deforming Earth to a 1D, dynamic marine ice sheet-shelf model. The evolution of the coupled model is explored for a suite of simulations in which we vary the bed slope and the forcing that initiates retreat. We find that the sea-level fall at the grounding line associated with a retreating ice sheet acts to slow the retreat; in simulations with shallow reversed bed slopes and/or small initial forcing, the drop in sea level can be sufficient to halt the retreat. The rate of sea-level change at the grounding line has an elastic component due to ongoing changes in ice-sheet geometry, and a viscous component due to past ice and ocean load changes. When the ice-sheet model is forced from steady state, on short timescales (< ~500 years), viscous effects may be ignored and grounding-line migration at a given time will depend on the local bedrock topography and on contemporaneous sea-level changes driven by ongoing ice-sheet mass flux. On longer timescales, an accurate assessment of the present stability of a marine ice sheet requires knowledge of its past evolution. Finally, we end with a discussion of the first results of simulations in which post-glacial sea-level physics is coupled to a 3D, dynamic marine ice sheet-ice shelf model.

  15. Eustatic sea level fluctuations induced by polar wander

    NASA Technical Reports Server (NTRS)

    Sabadini, Roberto; Doglioni, Carlo; Yuen, David A.

    1990-01-01

    It is shown here that polar wander of a viscoelastic, stratified earth can induce global sea level fluctuations comparable to the short-term component in eustatic sea-level curves. The sign of these fluctuations, which are very sensitive to the rheological stratification, depends on the geographical location of the observation point; rises and falls in sea level can thus be coeval in different parts of the world. This finding is a distinct contrast to the main assumption underlying the reconstruction of eustatic curves, namely that global sea-level events produce the same depositional sequence everywhere. It is proposed that polar wander should be added to the list of geophysical mechanisms that can control the third-order cycles in sea level.

  16. A 6,700 years sea-level record based on French Polynesian coral reefs

    NASA Astrophysics Data System (ADS)

    Hallmann, Nadine; Camoin, Gilbert; Eisenhauer, Anton; Vella, Claude; Samankassou, Elias; Botella, Albéric; Milne, Glenn; Fietzke, Jan; Dussouillez, Philippe

    2015-04-01

    Sea-level change during the Mid- to Late Holocene has a similar amplitude to the sea-level rise that is likely to occur before the end of the 21st century providing a unique opportunity to study the coastal response to sea-level change and to reveal an important baseline of natural climate variability prior to the industrial revolution. Mid- to Late Holocene relative sea-level change in French Polynesia was reconstructed using coral reef records from ten islands, which represent ideal settings for accurate sea-level studies because: 1) they can be regarded as tectonically stable during the relevant period (slow subsidence), 2) they are located far from former ice sheets (far-field), 3) they are characterized by a low tidal amplitude, and 4) they cover a wide range of latitudes which produces significantly improved constraints on GIA (Glacial Isostatic Adjustment) model parameters. Absolute U/Th dating of in situ coral colonies and their accurate positioning via GPS RTK (Real Time Kinematic) measurements is crucial for an accurate reconstruction of sea-level change. We focus mainly on the analysis of coral microatolls, which are sensitive low-tide recorders, as their vertical accretion is limited by the mean low water springs level. Growth pattern analysis allows the reconstruction of low-amplitude, high-frequency sea-level changes on centennial to sub-decadal time scales. A sea-level rise of less than 1 m is recorded between 6 and 3-3.5 ka, and is followed by a gradual fall in sea level that started around 2.5 ka and persisted until the past few centuries. The reconstructed sea-level curve therefore extends the Tahiti sea-level curve [Deschamps et al., 2012, Nature, 483, 559-564], and is in good agreement with a geophysical model tuned to fit far-field deglacial records [Bassett et al., 2005, Science, 309, 925-928].

  17. Continuous assimilation of simulated Geosat altimetric sea level into an eddy-resolving numerical ocean model. I - Sea level differences. II - Referenced sea level differences

    NASA Technical Reports Server (NTRS)

    White, Warren B.; Tai, Chang-Kou; Holland, William R.

    1990-01-01

    The optimal interpolation method of Lorenc (1981) was used to conduct continuous assimilation of altimetric sea level differences from the simulated Geosat exact repeat mission (ERM) into a three-layer quasi-geostrophic eddy-resolving numerical ocean box model that simulates the statistics of mesoscale eddy activity in the western North Pacific. Assimilation was conducted continuously as the Geosat tracks appeared in simulated real time/space, with each track repeating every 17 days, but occurring at different times and locations within the 17-day period, as would have occurred in a realistic nowcast situation. This interpolation method was also used to conduct the assimilation of referenced altimetric sea level differences into the same model, performing the referencing of altimetric sea sevel differences by using the simulated sea level. The results of this dynamical interpolation procedure are compared with those of a statistical (i.e., optimum) interpolation procedure.

  18. Inter-annual sea level variability in the southern South China Sea

    NASA Astrophysics Data System (ADS)

    Soumya, M.; Vethamony, P.; Tkalich, P.

    2015-10-01

    The South China Sea (SCS) is the largest marginal sea in the western Pacific Basin. Sea level anomalies (SLAs) in the southern South China Sea (SSCS) are assumed to be governed by various phenomena associated with the adjacent parts of the Indian Ocean and the Pacific Ocean. We have used monthly sea level anomalies obtained from 12 tide gauge stations of PSMSL and UHSLC and merged and gridded AVISO products of SLAs (sea level anomalies) derived from satellite altimeter. We find that IOD-influenced inter-annual variations are found only in the southwestern and southeastern coastal regions of SSCS. Our analysis reveals that inter-annual regional sea level drops are associated with positive phase of the IOD, and the rises with negative phase of the IOD. SLA variations at decadal scale in the southeastern and northern Gulf of Thailand correlate with Pacific Decadal Oscillations (PDO). Multiple linear regression analysis of inter-annual SLAs and climate indices shows that IOD induced inter-annual variations dominate in the southwestern SCS and it contributes to about ~ 40% of inter-annual sea level variation. Meanwhile, ENSO contributes to around ~ 30% variation in sea level in the southwestern and ~ 40% variation in the southeastern SSCS. The present study also suggests that inter-annual SLA variations in the SSCS can occur by ENSO and IOD induced changes in wind stress curl and volume transport variations.

  19. Investigations at regional scales of reconstruct sea level variability over the past 50 years

    NASA Astrophysics Data System (ADS)

    Becker, M.; Meyssignac, B.; Llovel, W.; Cazenave, A. A.; Rogel, P.

    2010-12-01

    Sea level rise is a major consequence of global warming, which threatens many low-lying, highly populated coastal regions of the world. In such regions, sea level rise amplifies other stresses due to natural phenomena (e.g., sediment load-induced ground subsidence in deltaic areas, vertical ground motions due to tectonics, volcanism and post-glacial rebound, etc.) or human activities (e.g., ground subsidence due to ground water pumping and/or oil extraction, urbanisation, etc.). Observations for the recent decades from tide gauges and satellite altimetry show that sea level rise is far from being geographically uniform. Here we present an analysis of decadal / multi-decadal sea level variations in a number of selected regions: Tropical Pacific, Indian Ocean, Gulf of Mexico and Caribbean region. For that purpose, we use a reconstruction of past sea level -last 50 years- based on the joint statistical analysis of tide gauge records and gridded sea level from an ocean circulation model. We highlight the sea level trends over the past 50 years in each region. Comparison between reconstructed sea-level trends with tide gauge records at sites not included in the reconstruction shows general good agreement, suggesting that regional trend patterns infer from the reconstruction are realistic (in addition, reconstructed sea-level agrees well with altimeter measurements since 1993). We find above-global average sea level rise since 1950 at several islands in the Eastern Tropical Pacific (Funafuti, Samoa, Kiribati, Cook Islands). Empirical Orthogonal Function (EOF) analyses are performed for each region to describe accurately the spatio-temporal interannual variability. We also compute spatial trend patterns in thermal expansion to determine which part of the observed regional sea level variability can be attributed to change in ocean temperature.

  20. Holocene sea level variations on the basis of integration of independent data sets

    SciTech Connect

    Sahagian, D.; Berkman, P. . Dept. of Geological Sciences and Byrd Polar Research Center)

    1992-01-01

    Variations in sea level through earth history have occurred at a wide variety of time scales. Sea level researchers have attacked the problem of measuring these sea level changes through a variety of approaches, each relevant only to the time scale in question, and usually only relevant to the specific locality from which a specific type of data are derived. There is a plethora of different data types that can and have been used (locally) for the measurement of Holocene sea level variations. The problem of merging different data sets for the purpose of constructing a global eustatic sea level curve for the Holocene has not previously been adequately addressed. The authors direct the efforts to that end. Numerous studies have been published regarding Holocene sea level changes. These have involved exposed fossil reef elevations, elevation of tidal deltas, elevation of depth of intertidal peat deposits, caves, tree rings, ice cores, moraines, eolian dune ridges, marine-cut terrace elevations, marine carbonate species, tide gauges, and lake level variations. Each of these data sets is based on particular set of assumptions, and is valid for a specific set of environments. In order to obtain the most accurate possible sea level curve for the Holocene, these data sets must be merged so that local and other influences can be filtered out of each data set. Since each data set involves very different measurements, each is scaled in order to define the sensitivity of the proxy measurement parameter to sea level, including error bounds. This effectively determines the temporal and spatial resolution of each data set. The level of independence of data sets is also quantified, in order to rule out the possibility of a common non-eustatic factor affecting more than one variety of data. The Holocene sea level curve is considered to be independent of other factors affecting the proxy data, and is taken to represent the relation between global ocean water and basin volumes.

  1. Blending of satellite and tide gauge sea level observations and its assimilation in a storm surge model of the North Sea and Baltic Sea

    NASA Astrophysics Data System (ADS)

    Madsen, Kristine S.; Høyer, Jacob L.; Fu, Weiwei; Donlon, Craig

    2015-09-01

    Coastal storm surge forecasts are typically derived from dedicated hydrodynamic model systems, relying on Numerical Weather Prediction (NWP) inputs. Uncertainty in the NWP wind field affects both the preconditioning and the forecast of sea level. Traditionally, tide gauge data have been used to limit preconditioning errors, providing point information. Here we utilize coastal satellite altimetry sea level observations. Careful processing techniques allow data to be retrieved up to 3 km from the coast, combining 1 Hz and 20 Hz data. The use of satellite altimetry directly is limited to times when the satellite passes over the area of interest. Instead, we use a stationary blending method developed by Madsen et al. (2007) to relate the coastal satellite altimetry with corresponding tide gauge measurements, allowing generation of sea level maps whenever tide gauge data are available. We apply the method in the North Sea and Baltic Sea, including the coastal zone, and test it for operational nowcasting and hindcasting of the sea level. The feasibility to assimilate the blended product into a hydrodynamic model is assessed, using the ensemble optimal interpolation method. A 2 year test simulation shows decreased sea level root mean square error of 7-43% and improved correlation by 1-23% in all modeled areas, when validated against independent tide gauges, indicating the feasibility to limit preconditioning errors for storm surge forecasting, using a relatively cost effective assimilation scheme.

  2. Sea level rise and variability around Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Tkalich, Pavel; Luu, Quang-Hung; Tay, Tze-Wei

    2014-05-01

    Peninsular Malaysia is bounded from the west by Malacca Strait and the Andaman Sea, both connected to the Indian Ocean, and from the east by South China Sea being largest marginal sea in the Pacific Basin. As a result, sea level along Peninsular Malaysia coast is assumed to be governed by various regional phenomena associated with the adjacent parts of the Indian and Pacific Oceans. At annual scale, sea level anomalies (SLAs) are generated by the Asian monsoon; interannual sea level variability is determined by the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD); whilst long term sea level trend is coordinated by the global climate change. To quantify the relative impacts of these multi-scale phenomena on sea level trend and variability surrounding the Peninsular Malaysia, long-term tide gauge record and satellite altimetry are used. During 1984-2011, relative sea level rise (SLR) rates in waters of Malacca Strait and eastern Peninsular Malaysia are found to be 2.4 ± 0.8 mm/yr and 2.7 ± 0.6 mm/yr, respectively. Discounting for their vertical land movements (0.8 ± 2.6 mm/yr and 0.9 ± 2.2 mm/yr, respectively), their pure SLR rates are 1.6 ± 3.4 mm/yr and 1.8 ± 2.8 mm/yr, respectively, which are lower than the global tendency. At interannual scale, ENSO affects sea level over the Malaysian east coast in the range of ± 5 cm with very high correlation coefficient. Meanwhile, IOD modulates sea level anomalies in the Malacca Strait in the range of ± 2 cm with high correlation coefficient. Interannual regional sea level drops are associated with El Niño events and positive phases of the IOD index; while the rises are correlated with La Niña episodes and the negative periods of the IOD index. Seasonally, SLAs are mainly monsoon-driven, in the order of 10-25 cm. Geographically, sea level responds differently to the monsoon: two cycles per year are observed in the Malacca Strait, presumably due to South Asian - Indian Monsoon; while single annual cycle is noted in the remaining region, mostly due to East Asian - Western Pacific Monsoon. These results imply that a narrow topographic constriction off Singapore may separate different modes of annual and interannual sea level variability along coastline of Peninsular Malaysia.

  3. Sea Level Trend and Variability in the Straits of Singapore and Malacca

    NASA Astrophysics Data System (ADS)

    Luu, Q.; Tkalich, P.

    2013-12-01

    The Straits of Singapore and Malacca (SSM) connect the Andaman Sea located northeast of the Indian Ocean to the South China Sea, the largest marginal sea situated in the tropical Pacific Ocean. Consequently, sea level in the SSM is assumed to be governed by various regional phenomena associated with the adjacent parts of Indian and Pacific Oceans. At annual scale sea level variability is dominant by the Asian monsoon. Interannual sea level signals are modulated by the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). In the long term, regional sea level is driven by the global climate change. However, relative impacts of these multi-scale phenomena on regional sea level in the SSM are yet to be quantified. In present study, publicly available tide gauge records and satellite altimetry data are used to derive long-term sea level trend and variability in SSM. We used the data from research-quality stations, including four located in the Singapore Strait (Tanjong Pagar, Raffles Lighthouse, Sultan Shoal and Sembawang) and seven situated in the Malacca Strait (Kelang, Keling, Kukup, Langkawji, Lumut, Penang and Ko Taphao Noi), each one having 25-39 year data up to the year 2011. Harmonic analysis is performed to filter out astronomic tides from the tide gauge records when necessary; and missing data are reconstructed using identified relationships between sea level and the governing phenomena. The obtained sea level anomalies (SLAs) and reconstructed mean sea level are then validated against satellite altimetry data from AVISO. At multi-decadal scale, annual measured sea level in the SSM is varying with global mean sea level, rising for the period 1984-2009 at the rate 1.8-2.3 mm/year in the Singapore Strait and 1.1-2.8 mm/year in the Malacca Strait. Interannual regional sea level drops are associated with El Niño events, while the rises are correlated with La Niña episodes; both variations are in the range of ×5 cm with correlation coefficient of -0.7 (in correspondence with the Multivariate ENSO Index). The IOD modulates interannual sea level variability only in the Malacca Strait in the range of ×3 cm with a correlation coefficient of -0.6 (with respect to the Dipole Mode Index). At annual scale, SLAs in the SSM are mainly monsoon-driven; of the order of 20 cm. Mean sea level in the Singapore Strait reach the peak during northeast monsoon and trough during southwest monsoon; while these in the Malacca Strait are highest at middle of both monsoons and lowest during their transitional monsoonal seasons. Global and regional signals are quantitatively captured in the SSM. In comparison with the global sea level trends, SSM sea level rise are larger for recent decades 1984-2009. Taking into account the rough estimate of land subsidence rates in Singapore (2006-2011) and Peninsular Malaysia (1994-2004), the trend of absolute sea level rise in SSM follows regional tendency. At interannual scale, ENSO modulates sea level variabilities in the entire SSM region, while IOD affects the Malacca Strait only. At annual scale, sea level responds differently to the Asian monsoon: quasi-periodic cycles are observed twice a year in the Malacca Strait, but once a year in the Singapore Strait. Such behavior implies that the narrow channel constriction between the Singapore and Malacca Straits may be a reason of different variability of sea level in the domains.

  4. Holocene sea-level oscillations and environmental changes on the Eastern Black Sea shelf

    USGS Publications Warehouse

    Ivanova, E.V.; Murdmaa, I.O.; Chepalyga, A.L.; Cronin, T. M.; Pasechnik, I.V.; Levchenko, O.V.; Howe, S.S.; Manushkina, A.V.; Platonova, E.A.

    2007-01-01

    A multi-proxy study of four sediment cores from the Eastern (Caucasian) Black Sea shelf revealed five transgressive-regressive cycles overprinted on the general trend of glacioeustatic sea-level rise during the last 11,000??14C yr. These cycles are well represented in micro-and macrofossil assemblages, sedimentation rates, and grain size variations. The oldest recovered sediments were deposited in the Neoeuxinian semi-freshwater basin (??? 10,500-9000??14C yr BP) and contain a Caspian-type mollusk fauna dominated by Dreissena rostriformis. Low ??18O and ??13C values are measured on this species. The first appearance of marine mollusks and ostracodes from the Mediterranean is established in this part of the Black Sea at ??? 8200??14C yr BP, i.e., about 1000-2000??yr later than the appearance of marine microfossils in the deeper part of the sea. The Early Holocene (Bugazian to Vityazevian) condensed section of shell and shelly mud sediments with at least two hiatuses represent a high-energy shelf-edge facies. It contains a transitional assemblage representing a mixture of Caspian and Mediterranean fauna. This pattern suggests a dual-flow regime via the Bosphorus after 8200??14C yr BP. Caspian species disappear and oligohaline species decrease in abundance during the Vityazevian-Prekalamitian cycle. Later, during the Middle to Late Holocene, low sea-level stands are characterized by shell layers, whereas silty mud with various mollusk and ostracode assemblages rapidly accumulated during transgressions. Restricted mud accumulation, as well as benthic faunal composition and abundance, suggest high-energy and well-ventilated bottom water during low sea-level stands. A trend of 18O enrichment in mollusk shells points to an increase in bottom-water salinity during the Vityazevian to Kalamitian transgressions (??? 7000 to 5700??14C yr BP) due to a more open connection with the Mediterranean, while a pronounced increase in polyhaline species abundance is established during the Kalamitian to Djemetean transgressions (??? 6400 to 2700??14C yr BP). However, the composition of the faunal assemblage indicates that bottom-water salinity never exceeded modern values of 18-20??psu. ?? 2006 Elsevier B.V. All rights reserved.

  5. Recent and projected changes in Dead Sea level and effects on mineral production from the sea

    USGS Publications Warehouse

    Sauer, Stanley P.

    1978-01-01

    Hydrologic data for the Dead Sea area were reviewed to assess the probable magnitude and rate of change of the water level of the Sea. Historical average annual Dead Sea levels range from a minimum of 399.4 meters below sea level in about 1818 to a maximum of 388.6 meters below in 1896. Present levels are rapidly approaching the historical low. There is a close correlation between Dead Sea level and accumulated departure from the mean of long-term rainfall except for the most recent period since 1964. During that period rainfall has been near the long-term average but water levels have continued to decline, in part due to abstractions for irrigation in the Jordan River basin. The dissolved-solids concentration of Dead Sea water presently is approximately 322,000 milligrams per liter and is generally well mixed. The increase in dissolved solids to the present high concentration has resulted in an evaporation rate less than that estimated in previous reports. An average annual inflow to the Sea of 900 cubic hectometers from all sources is required to stabilize the Sea at the present level. (Woodard-USGS)

  6. Long-term variability and trends of sea level storminess and extremes in European Seas

    NASA Astrophysics Data System (ADS)

    Vilibić, Ivica; Šepić, Jadranka

    2010-03-01

    This paper documents the variability and trends of mean storminess and extreme sea level amplitudes at selected long-term operating tide gauge stations located in the European Seas over different frequency bands, seasons and months. Six stations have been chosen for the analyses-Antalya, Ceuta, Rovinj, Newlyn, Wladyslawowo and Lerwick-which possess at least a half-centurial record of hourly or higher frequency sea level data. The data have been carefully inspected for time shifts and drifts in the record. The analyses included the extraction of sea level amplitudes (envelopes) over four frequency bands: super-diurnal frequencies (0-1 days), small-scale synoptic disturbances (1-3 days), large-scale synoptic disturbances (3-10 days) and planetary-scale disturbances (10-100 days). Interannual variability in sea level amplitudes is occasionally found to coincide with some known variability in the atmosphere. For example, the northern European stations have overall positive sea level storminess and extreme trends, which is opposite from the southern stations, confirming a northward shift in atmosphere storm tracks. Redistribution of sea level amplitudes between different seasons and different frequency bands has been observed at some stations in both variability and trends. The latter may be important for the assessment of a region's total hazard risks and vulnerability, as maximum storminess and extremes may or may not coincide with maximum mean sea level.

  7. Sea level variations at tropical Pacific islands since 1950

    NASA Astrophysics Data System (ADS)

    Becker, M.; Meyssignac, B.; Letetrel, C.; Llovel, W.; Cazenave, A.; Delcroix, T.

    2012-01-01

    The western tropical Pacific is usually considered as one of the most vulnerable regions of the world under present-day and future global warming. It is often reported that some islands of the region already suffer significant sea level rise. To clarify the latter concern, in the present study we estimate sea level rise and variability since 1950 in the western tropical Pacific region (20°S-15°N; 120°E-135°W). We estimate the total rate of sea level change at selected individual islands, as a result of climate variability and change, plus vertical ground motion where available. For that purpose, we reconstruct a global sea level field from 1950 to 2009, combining long (over 1950-2009) good quality tide gauge records with 50-year-long (1958-2007) gridded sea surface heights from the Ocean General Circulation Model DRAKKAR. The results confirm that El Niño-Southern Oscillation (ENSO) events have a strong modulating effect on the interannual sea level variability of the western tropical Pacific, with lower/higher-than-average sea level during El Niño/La Niña events, of the order of ± 20-30 cm. Besides this sub-decadal ENSO signature, sea level of the studied region also shows low-frequency (multi decadal) variability which superimposes to, thus in some areas amplifies current global mean sea level rise due to ocean warming and land ice loss. We use GPS precise positioning records whenever possible to estimate the vertical ground motion component that is locally superimposed to the climate-related sea level components. Superposition of global mean sea level rise, low-frequency regional variability and vertical ground motion shows that some islands of the region suffered significant 'total' sea level rise (i.e., that felt by the population) during the past 60 years. This is especially the case for the Funafuti Island (Tuvalu) where the "total" rate of rise is found to be about 3 times larger than the global mean sea level rise over 1950-2009.

  8. Future sea level rise constrained by observations and long-term commitment

    PubMed Central

    Mengel, Matthias; Levermann, Anders; Frieler, Katja; Robinson, Alexander; Marzeion, Ben; Winkelmann, Ricarda

    2016-01-01

    Sea level has been steadily rising over the past century, predominantly due to anthropogenic climate change. The rate of sea level rise will keep increasing with continued global warming, and, even if temperatures are stabilized through the phasing out of greenhouse gas emissions, sea level is still expected to rise for centuries. This will affect coastal areas worldwide, and robust projections are needed to assess mitigation options and guide adaptation measures. Here we combine the equilibrium response of the main sea level rise contributions with their last century's observed contribution to constrain projections of future sea level rise. Our model is calibrated to a set of observations for each contribution, and the observational and climate uncertainties are combined to produce uncertainty ranges for 21st century sea level rise. We project anthropogenic sea level rise of 28–56 cm, 37–77 cm, and 57–131 cm in 2100 for the greenhouse gas concentration scenarios RCP26, RCP45, and RCP85, respectively. Our uncertainty ranges for total sea level rise overlap with the process-based estimates of the Intergovernmental Panel on Climate Change. The “constrained extrapolation” approach generalizes earlier global semiempirical models and may therefore lead to a better understanding of the discrepancies with process-based projections. PMID:26903648

  9. Future sea level rise constrained by observations and long-term commitment.

    PubMed

    Mengel, Matthias; Levermann, Anders; Frieler, Katja; Robinson, Alexander; Marzeion, Ben; Winkelmann, Ricarda

    2016-03-01

    Sea level has been steadily rising over the past century, predominantly due to anthropogenic climate change. The rate of sea level rise will keep increasing with continued global warming, and, even if temperatures are stabilized through the phasing out of greenhouse gas emissions, sea level is still expected to rise for centuries. This will affect coastal areas worldwide, and robust projections are needed to assess mitigation options and guide adaptation measures. Here we combine the equilibrium response of the main sea level rise contributions with their last century's observed contribution to constrain projections of future sea level rise. Our model is calibrated to a set of observations for each contribution, and the observational and climate uncertainties are combined to produce uncertainty ranges for 21st century sea level rise. We project anthropogenic sea level rise of 28-56 cm, 37-77 cm, and 57-131 cm in 2100 for the greenhouse gas concentration scenarios RCP26, RCP45, and RCP85, respectively. Our uncertainty ranges for total sea level rise overlap with the process-based estimates of the Intergovernmental Panel on Climate Change. The "constrained extrapolation" approach generalizes earlier global semiempirical models and may therefore lead to a better understanding of the discrepancies with process-based projections. PMID:26903648

  10. Sea Level Data Archaeology for the Global Sea Level Observing System (GLOSS)

    NASA Astrophysics Data System (ADS)

    Bradshaw, Elizabeth; Matthews, Andy; Rickards, Lesley; Jevrejeva, Svetlana

    2015-04-01

    The Global Sea Level Observing System (GLOSS) was set up in 1985 to collect long term tide gauge observations and has carried out a number of data archaeology activities over the past decade, including sending member organisations questionnaires to report on their repositories. The GLOSS Group of Experts (GLOSS GE) is looking to future developments in sea level data archaeology and will provide its user community with guidance on finding, digitising, quality controlling and distributing historic records. Many records may not be held in organisational archives and may instead by in national libraries, archives and other collections. GLOSS will promote a Citizen Science approach to discovering long term records by providing tools for volunteers to report data. Tide gauge data come in two different formats, charts and hand-written ledgers. Charts are paper analogue records generated by the mechanical instrument driving a pen trace. Several GLOSS members have developed software to automatically digitise these charts and the various methods were reported in a paper on automated techniques for the digitization of archived mareograms, delivered to the GLOSS GE 13th meeting. GLOSS is creating a repository of software for scanning analogue charts. NUNIEAU is the only publically available software for digitising tide gauge charts but other organisations have developed their own tide gauge digitising software that is available internally. There are several other freely available software packages that convert image data to numerical values. GLOSS could coordinate a comparison study of the various different digitising software programs by: Sending the same charts to each organisation and asking everyone to digitise them using their own procedures Comparing the digitised data Providing recommendations to the GLOSS community The other major form of analogue sea level data is handwritten ledgers, which are usually observations of high and low waters, but sometimes contain higher frequency data. The standard current method for digitising these data is to enter the values manually, which has been performed by GLOSS countries, including France and Spain. The GLOSS GE is exploring other methods for use in the future as this process is time consuming. Current projects to improve Handwritten Text Recognition (HTR) tend to be working with the written word and so require knowledge of sentence structures and word occurrence probabilities to reconstruct sentences e.g. tranScriptorium (European Union's Seventh Framework Programme funded project). This approach would not be applicable to sea level data, however tidal data by its very nature contains periodicity and predictability. HTR technology could be adapted to take this into account and improve the automatic digitisation of handwritten tide gauge ledgers. There are many challenges facing the sea level data archaeology community, but it is hoped that improvements in technology can overcome some of the obstacles: Faster automated digitisation of tide gauge charts Minimal user input Automatic transcribing of handwritten ledgers The GLOSS GE will provide a central location to share software, guidelines for quality controlling data and the GLOSS data archive centres will be the repository of the newly created datasets.

  11. Past sea level reconstruction and variability of sea level trend patterns over 1970-2001 in the Mediterranean Sea basin derived from Altimetry and 2 long OGCM runs.

    NASA Astrophysics Data System (ADS)

    Meyssignac, Benoit; Cazenave, Anny; Morrow, Rosemary; Marcos, Marta; Calafat, Francisco; Llovel, William

    2010-05-01

    For the past decades, there are no direct basin-scale sea level observations concerning the spatial sea level patterns and their evolution in the Mediterranean Sea. In order to understand physical processes driving sea level variability it is important to know the dominant modes of regional variability on interannual/decadal/multidecadal time scale in the Mediterranean basin. It is also of interest for assessing ocean circulation models dedicated to the Mediterranean Sea. For these purposes, we have developed a reconstruction method of past Mediterranean sea level (since 1970) that combines long tide gauge records of limited spatial coverage and 2-D sea level patterns based on the AVISO altimetry dataset and on runs from two different Ocean General Circulation Models (OGCMs). In the latter case, we use runs from the ORCA05 model (without data assimilation) over 1958-2005 available from the DRAKKAR project and the SODA reanalysis over 1958-2005 available from GODAE (Carton et al., 2008), assimilating all available in situ temperature, salinity and sea level data. We also perform the past sea level reconstruction over the Mediterranean Sea using 2-D spatial patterns from satellite altimetry. The three sea level reconstructions are inter-compared, together with results from a published study (Calafat and Gomis, 2009). The dominant modes of temporal variability are discussed and sea level hindcasts at tide gauge sites not used in the analysis are compared to actual observations. Comparisons with steric sea level patterns based on in situ hydrographic data are also presented and discussed with regard to the conclusions of past studies based on tide gauge records analysis. .

  12. Upper Limit for Sea Level Projections by 2100

    NASA Astrophysics Data System (ADS)

    Jevrejeva, Svetlana; Grinsted, Aslak; Moore, John

    2015-04-01

    With more than 150 million people living within 1 m of high tide future sea level rise is one of the most damaging aspects of warming climate. The latest Intergovernmental Panel on Climate Change report (AR5 IPCC) noted that a 0.5 m rise in mean sea level will result in a dramatic increase the frequency of high water extremes - by an order of magnitude, or more in some regions. Thus the flood threat to the rapidly growing urban populations and associated infrastructure in coastal areas are major concerns for society. Hence, impact assessment, risk management, adaptation strategy and long-term decision making in coastal areas depend on projections of mean sea level and crucially its low probability, high impact, upper range. We construct the probability density function of global sea level at 2100, estimating that sea level rises larger than 180 cm are less than 5% probable. An upper limit for global sea level rise of 190 cm is assembled by summing the highest estimates of individual sea level rise components simulated by process based models with the RCP8.5 scenario. The agreement between the methods may suggest more confidence than is warranted since large uncertainties remain due to the lack of scenario-dependent projections from ice sheet dynamical models, particularly for mass loss from marine-based fast flowing outlet glaciers in Antarctica.

  13. Upper Limit for Sea Level Projections by 2100

    NASA Astrophysics Data System (ADS)

    Jevrejeva, S.; Grinsted, A.; Moore, J. C.

    2014-12-01

    With more than 150 million people living within 1 m of high tide future sea level rise is one of the most damaging aspects of warming climate. The latest Intergovernmental Panel on Climate Change report (AR5 IPCC) noted that a 0.5 m rise in mean sea level will result in a dramatic increase the frequency of high water extremes - by an order of magnitude, or more in some regions. Thus the flood threat to the rapidly growing urban populations and associated infrastructure in coastal areas are major concerns for society. Hence, impact assessment, risk management, adaptation strategy and long-term decision making in coastal areas depend on projections of mean sea level and crucially its low probability, high impact, upper range. We construct the probability density function of global sea level at 2100, estimating that sea level rises larger than 180 cm are less than 5% probable. An upper limit for global sea level rise of 190 cm is assembled by summing the highest estimates of individual sea level rise components simulated by process based models with the RCP8.5 scenario. The agreement between the methods may suggest more confidence than is warranted since large uncertainties remain due to the lack of scenario-dependent projections from ice sheet dynamical models, particularly for mass loss from marine-based fast flowing outlet glaciers in Antarctica.

  14. Sea level change: lessons from the geologic record

    USGS Publications Warehouse

    U.S. Geological Survey

    1995-01-01

    Rising sea level is potentially one of the most serious impacts of climatic change. Even a small sea level rise would have serious economic consequences because it would cause extensive damage to the world's coastal regions. Sea level can rise in the future because the ocean surface can expand due to warming and because polar ice sheets and mountain glaciers can melt, increasing the ocean's volume of water. Today, ice caps on Antarctica and Greenland contain 91 and 8 percent of the world's ice, respectively. The world's mountain glaciers together contain only about 1 percent. Melting all this ice would raise sea level about 80 meters. Although this extreme scenario is not expected, geologists know that sea level can rise and fall rapidly due to changing volume of ice on continents. For example, during the last ice age, about 18,000 years ago, continental ice sheets contained more than double the modem volume of ice. As ice sheets melted, sea level rose 2 to 3 meters per century, and possibly faster during certain times. During periods in which global climate was very warm, polar ice was reduced and sea level was higher than today.

  15. Dynamic sea level changes following changes in the thermohaline circulation

    NASA Astrophysics Data System (ADS)

    Levermann, Anders; Griesel, Alexa; Hofmann, Matthias; Montoya, Marisa; Rahmstorf, Stefan

    2005-03-01

    Using the coupled climate model CLIMBER-3?, we investigate changes in sea surface elevation due to a weakening of the thermohaline circulation (THC). In addition to a global sea level rise due to a warming of the deep sea, this leads to a regional dynamic sea level change which follows quasi-instantaneously any change in the ocean circulation. We show that the magnitude of this dynamic effect can locally reach up to ~1 m, depending on the initial THC strength. In some regions the rate of change can be up to 20-25 mm/yr. The emerging patterns are discussed with respect to the oceanic circulation changes. Most prominent is a south-north gradient reflecting the changes in geostrophic surface currents. Our results suggest that an analysis of observed sea level change patterns could be useful for monitoring the THC strength.

  16. Subsidence and Relative Sea-level Rise in Threatened Deltas

    NASA Astrophysics Data System (ADS)

    Syvitski, J. P.; Higgins, S.

    2014-12-01

    In determining the risk lowland deltaic topography, as threatened by sea level rise and land subsidence, a number of important processes must be evaluated. Sea level rise is a global process but with local manifestations. Asian deltas have been experiencing higher rates of sea level rise due to the steric impact on dynamic (ocean) topography. Other large scale geophysical impacts on relative sea level at the local scale include the isostatic and flexural response to Holocene sea level history, Holocene sediment loads, and in former ice sheet zones --- glacial rebound. Tectonism does play a role on relative sea level rise, particularly in South America where the Eastern coastline, particularly Argentina, is rising relative to regional sea levels. Subsidence is impacted by both natural ground compaction, and accelerated compaction due to, for example, peat oxidation that often has a human driver (e.g. swamp reclammation). Subsidence is also impacted by the extraction of deeper deposits of petroleum and water. Rates of delta subsidence vary widely, depending on the magnitude of the anthropogenic driver, from a few mm/y to 100's of mm/y. Ground water withdrawal is the dominant reason behind much of the world's coastal subsidence, with important exceptions. On average subsidence rates (all causes) now contribute to local sea level innundations at rates four times faster then sea level is rising. New technologies, particularly InSAR and GPS methods, can often pin point the local cause (e.g. water withdrawl for agriculture versus for aquaculture). Subsurface soil or rock heterogeneity, and other very local geological patterns such as historical river pathways, also influence the temporal and spatial patterns associated with delta subsidence.

  17. Response of the wadden sea to a rising sea level: a Predictive empirical model

    NASA Astrophysics Data System (ADS)

    Flemming, Burghard W.; Bartholomä, Alexander

    1997-09-01

    A clue to the stratigraphic evolution in the case of a barrier island migrating up against a landward obstruction has recently been obtained from a detailed analysis of sediment patterns in the mesotidal backbarrier environment of the Wadden Sea (southern North Sea). Here the landward boundary is man-made and comprises a continuous dike line constructed in the wake of extensive land reclamation over the past 1000 years. Sea-level rise currently amounts to 25 cm/century. The system is further characterized by a lack of external sediment supply and a pronounced cross-shore energy gradient resulting in progressive landward fining of the backbarrier sediments. Adjacent to the dike the depositional system today is dominated by mixed flats with mud contents rarely exceeding 30%. Land reclamation has thus truncated the natural succession of sediment facies by eliminating mud flats and salt marshes. Contrary to expectations, the re-establishment of a complete but compressed facies sequence incorporating mud flats and salt marshes has not materialized. This would suggest that energy levels at the foot of the dike today are considerably higher than was previously the case along the undiked shoreline. A quantitative relative measure of backbarrier energy levels is the mean settling velocity of the sediment. In extreme cases the system has reached the stage where the finest sands with settling velocities below 0.3 cm s-1 (mean grain sizes < 0.1 mm) are being eliminated. It is postulated that, in the wake of continued sea-level rise and associated landward migration of the barrier island system, the sediment elimination process adjacent to the dike will continue and involve progressively coarser sediments. In the case of the Wadden Sea, the settling-lag and scour-lag mechanism by which fine-grained sediments are carried shoreward must be modified to incorporate an export loop for those particle sizes which have settling velocities below the local elimination threshold. The sediment elimination process outlined above is triggered by the rigid man-made boundary which prevents landward displacement of the depositional system onto the adjacent coastal plain. This model may be applicable to natural systems migrating towards a coastal cliff or a steeply rising hinterland in the course of transgression. It is postulated that in such cases an analogous loss of intertidal facies belts adjacent to the shoreline will occur and that this should be revealed in the stratigraphic record by upward coarsening, onlapping sequences.

  18. Constructing temperature-dependent regional sea level scenarios

    NASA Astrophysics Data System (ADS)

    de Vries, Hylke; Katsman, Caroline

    2014-05-01

    Scenarios for 21st century regional sea-level change are constructed using output from 42 coupled global climate models that contributed to the CMIP5 database. Global temperature change is used as a steering variable, rather than the more widely used stratification across different representative concentration pathways (RCPS), as in for example the latest IPCC-report. All major contributors to sea-level rise are included, except for glacial isostatic adjustment. The main target area is the Dutch coast for which the effects of sea-level rise become increasingly relevant.

  19. Millennial, centennial and decadal sea- level change in Florida, USA

    NASA Astrophysics Data System (ADS)

    Kemp, A.; Hawkes, A. D.; Donnelly, J. P.; Horton, B. P.

    2012-12-01

    Reconstructions of relative sea-level changes on millennial timescales provide data against which to test and calibrate Earth-Ice models. On the U.S. mid-Atlantic coast they constrain the geometry of the Laurentide Ice Sheet's collapsing forebulge. Sea -level data from southeastern Atlantic coast additionally constrain ice-equivalent meltwater input. Here we produce the first Holocene sea-level curve for Florida and Georgia from the St. Mary's River using agglutinated foraminifera preserved in radiocarbon-dated brackish and salt-marsh sediment. The use of foraminfera as sea-level indicators was underpinned by local and regional datasets describing the modern distribution of assemblages that are analogues for those preserved in buried sediment. This approach produced 25 index points that record 5.2 m of relative sea level rise over the last 8000 years with no evidence of a mid Holocene high stand. These reconstructions indicate that existing GIA models do not replicate proxy reconstructions and that northern Florida is subsiding in response to ongoing forebulge collapse at an estimated rate of approximately 0.3 mm/yr. Over multi decadal time scales, detailed sea level reconstructions provide an appropriate geological context for modern rates of sea-level rise. Reconstructions spanning the last 2000 years of known climate variability are important for developing models with predictive capacity that link climate and sea level changes. A reconstruction of sea-level changes since 2000 years BP was developed using a core of brackish marsh sediment from the Nassau River in Florida. Foraminifera estimated the elevation of former sea level with an uncertainty of 10 cm. Consistent downcore assemblages indicate that the marsh maintained its tidal elevation for 2000 years. An age depth model was developed for the core results from radiocarbon dating, 210Pb and 137Cs. The resulting relative sea level record was adjusted for the contribution made by glacio-isostatic subsidence to reveal climate-related sea level variability. The proxy dataset reproduces trends recorded by reliable nearby tide gauges at Fernandina Beach, FL and Fort Pulaski, GA and indicates that modern rates of rise were initiated in the latest part of the 19th century and are greater than any persistent trend in the last 2000 years.

  20. An alternative to reduction of surface pressure to sea level

    NASA Technical Reports Server (NTRS)

    Deardorff, J. W.

    1982-01-01

    The pitfalls of the present method of reducing surface pressure to sea level are reviewed, and an alternative, adjusted pressure, P, is proposed. P is obtained from solution of a Poisson equation over a continental region, using the simplest boundary condition along the perimeter or coastline where P equals the sea level pressure. The use of P would avoid the empiricisms and disadvantages of pressure reduction to sea level, and would produce surface pressure charts which depict the true geostrophic wind at the surface.

  1. Evidence for glacial control of rapid sea level changes in the early cretaceous

    SciTech Connect

    Stoll, H.M.; Schrag, D.P.

    1996-06-21

    Lower Cretaceous bulk carbonate from deep sea sediments records sudden inputs of strontium resulting from the exposure of continental shelves. Strontium data from an interval spanning 7 million years in the Berriasian-Valanginian imply that global sea level fluctuated about 50 meters over time scales of 200,000 to 500,000 years, which is in agreement with the Exxon sea level curve. Oxygen isotope measurements indicate that the growth of continental ice sheets caused these rapid sea level changes. If glaciation caused all the rapid sea level changes in the cretaceous that are indicated by the Exxon curve, then an Antarctic ice sheet may have existed despite overall climatic warmth. 30 refs., 1 fig.

  2. The multimillennial sea-level commitment of global warming

    PubMed Central

    Levermann, Anders; Clark, Peter U.; Marzeion, Ben; Milne, Glenn A.; Pollard, David; Radic, Valentina; Robinson, Alexander

    2013-01-01

    Global mean sea level has been steadily rising over the last century, is projected to increase by the end of this century, and will continue to rise beyond the year 2100 unless the current global mean temperature trend is reversed. Inertia in the climate and global carbon system, however, causes the global mean temperature to decline slowly even after greenhouse gas emissions have ceased, raising the question of how much sea-level commitment is expected for different levels of global mean temperature increase above preindustrial levels. Although sea-level rise over the last century has been dominated by ocean warming and loss of glaciers, the sensitivity suggested from records of past sea levels indicates important contributions should also be expected from the Greenland and Antarctic Ice Sheets. Uncertainties in the paleo-reconstructions, however, necessitate additional strategies to better constrain the sea-level commitment. Here we combine paleo-evidence with simulations from physical models to estimate the future sea-level commitment on a multimillennial time scale and compute associated regional sea-level patterns. Oceanic thermal expansion and the Antarctic Ice Sheet contribute quasi-linearly, with 0.4 m °C−1 and 1.2 m °C−1 of warming, respectively. The saturation of the contribution from glaciers is overcompensated by the nonlinear response of the Greenland Ice Sheet. As a consequence we are committed to a sea-level rise of approximately 2.3 m °C−1 within the next 2,000 y. Considering the lifetime of anthropogenic greenhouse gases, this imposes the need for fundamental adaptation strategies on multicentennial time scales. PMID:23858443

  3. The multimillennial sea-level commitment of global warming.

    PubMed

    Levermann, Anders; Clark, Peter U; Marzeion, Ben; Milne, Glenn A; Pollard, David; Radic, Valentina; Robinson, Alexander

    2013-08-20

    Global mean sea level has been steadily rising over the last century, is projected to increase by the end of this century, and will continue to rise beyond the year 2100 unless the current global mean temperature trend is reversed. Inertia in the climate and global carbon system, however, causes the global mean temperature to decline slowly even after greenhouse gas emissions have ceased, raising the question of how much sea-level commitment is expected for different levels of global mean temperature increase above preindustrial levels. Although sea-level rise over the last century has been dominated by ocean warming and loss of glaciers, the sensitivity suggested from records of past sea levels indicates important contributions should also be expected from the Greenland and Antarctic Ice Sheets. Uncertainties in the paleo-reconstructions, however, necessitate additional strategies to better constrain the sea-level commitment. Here we combine paleo-evidence with simulations from physical models to estimate the future sea-level commitment on a multimillennial time scale and compute associated regional sea-level patterns. Oceanic thermal expansion and the Antarctic Ice Sheet contribute quasi-linearly, with 0.4 m °C(-1) and 1.2 m °C(-1) of warming, respectively. The saturation of the contribution from glaciers is overcompensated by the nonlinear response of the Greenland Ice Sheet. As a consequence we are committed to a sea-level rise of approximately 2.3 m °C(-1) within the next 2,000 y. Considering the lifetime of anthropogenic greenhouse gases, this imposes the need for fundamental adaptation strategies on multicentennial time scales. PMID:23858443

  4. Observed mean sea level changes around the North Sea coastline from 1800 to present

    NASA Astrophysics Data System (ADS)

    Wahl, T.; Haigh, I. D.; Woodworth, P. L.; Albrecht, F.; Dillingh, D.; Jensen, J.; Nicholls, R. J.; Weisse, R.; Wöppelmann, G.

    2013-09-01

    This paper assesses historic changes in mean sea level around the coastline of the North Sea, one of the most densely populated coasts in the world. Typically, such analyses have been conducted at a national level, and detailed geographically wider analyses have not been undertaken for about 20 years. We analyse long records (up to 200 years) from 30 tide gauge sites, which are reasonably uniformly distributed along the coastline, and: (1) calculate relative sea level trends; (2) examine the inter-annual and decadal variations; (3) estimate regional geocentric (sometimes also referred to as 'absolute') sea level rise throughout the 20th century; and (4) assess the evidence for regional acceleration of sea-level rise. Relative sea level changes are broadly consistent with known vertical land movement patterns. The inter-annual and decadal variability is partly coherent across the region, but with some differences between the Inner North Sea and the English Channel. Data sets from various sources are used to provide estimates of the geocentric sea level changes. The long-term geocentric mean sea level trend for the 1900 to 2011 period is estimated to be 1.5 ± 0.1 mm/yr for the entire North Sea region. The trend is slightly higher for the Inner North Sea (i.e. 1.6 ± 0.1 mm/yr), and smaller but not significantly different on the 95% confidence level for the English Channel (i.e. 1.2 ± 0.1 mm/yr). The uncertainties in the estimates of vertical land movement rates are still large, and the results from a broad range of approaches for determining these rates are not consistent. Periods of sea level rise acceleration are detected at different times throughout the last 200 years and are to some extent related to air pressure variations. The recent rates of sea level rise (i.e. over the last two to three decades) are high compared to the long-term average, but are comparable to those which have been observed at other times in the late 19th and 20th century.

  5. Regional Sea Level Variation: California Coastal Subsidence (Invited)

    NASA Astrophysics Data System (ADS)

    Blewitt, G.; Hammond, W. C.; Nerem, R.

    2013-12-01

    Satellite altimetry over the last two decades has measured variations in geocentric sea level (GSL), relative to the Earth system center of mass, providing valuable data to test models of physical oceanography and the effects of global climate change. The societal impacts of sea level change however relate to variations in local sea level (LSL), relative to the land at the coast. Therefore, assessing the impacts of sea level change requires coastal measurements of vertical land motion (VLM). Indeed, ΔLSL = ΔGSL - ΔVLM, with subsidence mapping 1:1 into LSL. Measurements of secular coastal VLM also allow tide-gauge data to test models of GSL over the last century in some locations, which cannot be provided by satellite data. Here we use GPS geodetic data within 15 km of the US west coast to infer regional, secular VLM. A total of 89 GPS stations met the criteria that time series span >4.5 yr, and do not have obvious non-linear variation, as may be caused by local instability. VLM rates for the GPS stations are derived in the secular reference frame ITRF2008, which aligns with the Earth system center of mass to ×0.5 mm/yr. We find that regional VLM has different behavior north and south of the Mendocino Triple Junction (MTJ). The California coast has a coherent regional pattern of subsidence averaging 0.5 mm/yr, with an increasing trend to the north. This trend generally matches GIA model predictions. Around San Francisco Bay, the observed coastal subsidence of 1.0 mm/yr coherently decreases moving away from the Pacific Ocean to very small subsidence on the east shores of the bay. This gradient is likely caused by San Andreas-Hayward Fault tectonics, and possibly by differential surface loading across the bay and Sacramento-San Joachim River Delta. Thus in addition to the trend in subsidence from GIA going northward along the California coast, tectonics may also play a role where the plate boundary fault system approaches the coast. In contrast, we find that VLM of the coast north of the MTJ in Oregon and Washington has the opposite sign (uplift) and varies with distance between the coast and the trench, as may be expected from elastic strain accumulation at the locked subduction zone, coupled with a contrast in rheological structure affecting GIA. In terms of LSL and hence societal impact, our measured mean California subsidence of 0.5 mm/yr approximately cancels with GIA models of global GSL lowering at a similar rate. This GSL lowering is caused by the increasing volume of ocean basins as the mantle flows away from under the oceans in isostatic response to >100 m of sea level rise following Pleistocene deglaciation. So the net LSL in California caused by coastal VLM plus GSL lowering by GIA is ~0.5 mm/yr LSL rise to the north, and ~0.5 mm/yr lowering to the south. Since our VLM estimates do not account for large earthquakes, the trends in LSL over geological time could look quite different. Given that our GPS time series are selected from a globally consistent set from >11,000 stations, we note that similar studies could be applied using our dataset in a seamless way over coastlines across the globe, depending on available station coverage.

  6. Two Decades of Global and Regional Sea Level Observations from the ESA Climate Change Initiative Sea Level Project

    NASA Astrophysics Data System (ADS)

    Legeais, JeanFrancois; Larnicol, Gilles; Cazenave, Anny; Ablain, Michael; Benveniste, Jrme; Lucas, BrunoManuel; Timms, Gary; Johannessen, Johnny; Knudsen, Per; Cipollini, Paolo; Roca, Monica; Rudenko, Sergei; Fernandes, Joana; Balmaseda, Magdalena; Quartly, Graham; Fenoglio-Marc, Luciana; Scharfennberg, Martin; Meyssignac, Benoit; Guinle, Thierry; Andersen, Ole

    2015-04-01

    Sea level is a very sensitive index of climate change and variability. Sea level integrates the ocean warming, mountain glaciers and ice sheet melting. Understanding the sea level variability and changes implies an accurate monitoring of the sea level variable at climate scales, in addition to understanding the ocean variability and the exchanges between ocean, land, cryosphere, and atmosphere. That is why Sea Level is one of the Essential Climate Variables (ECV) selected in the frame of the ESA Climate Change Initiative (CCI) program. It aims at providing long-term monitoring of the sea level ECV with regular updates, as required for climate studies. After a first phase (2011-2013), the program has started in 2014 a second phase of 3 years. The objectives of this second phase are to involve the climate research community, to refine their needs and collect their feedbacks on product quality, to develop, test and select the best algorithms and standards to generate an updated climate time series and to produce and validate the Sea Level ECV product. This will better answer the climate user needs by improving the quality of the Sea Level products and maintain a sustain service for an up-to-date production. To this extent, the ECV time series has been extended and it now covers the period 1993-2013. We will firstly present the main achievements of the ESA CCI Sea Level Project. On the one hand, the major steps required to produce the 21 years climate time series are briefly described: collect and refine the user requirements, development of adapted algorithms for climate applications and specification of the production system. On the other hand, the product characteristics are described as well as the results from product validation, performed by several groups of the ocean and climate modeling community. At last, the work plan and key challenges of the second phase of the project are described.

  7. Characterization of extreme sea level at the European coast

    NASA Astrophysics Data System (ADS)

    Elizalde, Alberto; Jorda, Gabriel; Mathis, Moritz; Mikolajewicz, Uwe

    2015-04-01

    Extreme high sea levels arise as a combination of storm surges and particular high tides events. Future climate simulations not only project changes in the atmospheric circulation, which induces changes in the wind conditions, but also an increase in the global mean sea level by thermal expansion and ice melting. Such changes increase the risk of coastal flooding, which represents a possible hazard for human activities. Therefore, it is important to investigate the pattern of sea level variability and long-term trends at coastal areas. In order to analyze further extreme sea level events at the European coast in the future climate projections, a new setup for the global ocean model MPIOM coupled with the regional atmosphere model REMO is prepared. The MPIOM irregular grid has enhanced resolution in the European region to resolve the North and the Mediterranean Seas (up to 11 x 11 km at the North Sea). The ocean model includes as well the full luni-solar ephemeridic tidal potential for tides simulation. To simulate the air-sea interaction, the regional atmospheric model REMO is interactively coupled to the ocean model over Europe. Such region corresponds to the EuroCORDEX domain with a 50 x 50 km resolution. Besides the standard fluxes of heat, mass (freshwater), momentum and turbulent energy input, the ocean model is also forced with sea level pressure, in order to be able to capture the full variation of sea level. The hydrological budget within the study domain is closed using a hydrological discharge model. With this model, simulations for present climate and future climate scenarios are carried out to study transient changes on the sea level and extreme events. As a first step, two simulations (coupled and uncoupled ocean) driven by reanalysis data (ERA40) have been conducted. They are used as reference runs to evaluate the climate projection simulations. For selected locations at the coast side, time series of sea level are separated on its different components: tides, short time atmospheric process influence (1-30 days), seasonal cycle and interannual variability. Every sea level component is statistically compared with data from local tide gauges.

  8. Chronology of fluctuating sea levels since the triassic.

    PubMed

    Haq, B U; Hardenbol, J; Vail, P R

    1987-03-01

    Advances in sequence stratigraphy and the development of depositional models have helped explain the origin of genetically related sedimentary packages during sea level cycles. These concepts have provided the basis for the recognition of sea level events in subsurface data and in outcrops of marine sediments around the world. Knowledge of these events has led to a new generation of Mesozoic and Cenozoic global cycle charts that chronicle the history of sea level fluctuations during the past 250 million years in greater detail than was possible from seismic-stratigraphic data alone. An effort has been made to develop a realistic and accurate time scale and widely applicable chronostratigraphy and to integrate depositional sequences documented in public domain outcrop sections from various basins with this chronostratigraphic framework. A description of this approach and an account of the results, illustrated by sea level cycle charts of the Cenozoic, Cretaceous, Jurassic, and Triassic intervals, are presented. PMID:17818978

  9. [Book review] Sea level rise: history and consequences

    USGS Publications Warehouse

    Grossman, Eric E.

    2004-01-01

    Review of: Sea level Rise: history and consequences. Bruce Douglas, Michael S. Kearney and Stephen P. Leatherman (eds), Sand Diego: Academic Press, 2001, 232 pp. plus CD-RIM, US$64.95, hardback. ISBN 0-12-221345-9.

  10. Seasonal coastal sea level prediction using a dynamical model

    NASA Astrophysics Data System (ADS)

    McIntosh, Peter C.; Church, John A.; Miles, Elaine R.; Ridgway, Ken; Spillman, Claire M.

    2015-08-01

    Sea level varies on a range of time scales from tidal to decadal and centennial change. To date, little attention has been focussed on the prediction of interannual sea level anomalies. Here we demonstrate that forecasts of coastal sea level anomalies from the dynamical Predictive Ocean Atmosphere Model for Australia (POAMA) have significant skill throughout the equatorial Pacific and along the eastern boundaries of the Pacific and Indian Oceans at lead times out to 8 months. POAMA forecasts for the western Pacific generally have greater skill than persistence, particularly at longer lead times. POAMA also has comparable or greater skill than previously published statistical forecasts from both a Markov model and canonical correlation analysis. Our results indicate the capability of physically based models to address the challenge of providing skillful forecasts of seasonal sea level fluctuations for coastal communities over a broad area and at a range of lead times.

  11. Chronology of fluctuating sea levels since the triassic

    SciTech Connect

    Haq, B.U.; Hardenbol, J.; Vail, P.R.

    1987-03-06

    Advances in sequence stratigraphy and the development of depositional models have helped explain the origin of genetically related sedimentary packages during sea level cycles. These concepts have provided the basis for the recognition of sea level events in subsurface data and in outcrops of marine sediments around the world. Knowledge of these events has led to a new generation of Mesozoic and Cenozoic global cycle charts that chronicle the history of sea level fluctuations during the past 250 million years in greater detail than was possible from seismic-stratigraphic data alone. An effort has been made to develop a realistic and accurate time scale and widely applicable chronostratigraphy and to integrate depositional sequences documented in public domain outcrop sections from various basins with this chronostratigraphic framework. A description of this approach and an account of the results, illustrated by sea level cycle charts of the Cenozoic, Cretaceous, Jurassic, and Triassic intervals, are presented.

  12. Beachrock as an indicator of Holocene sea level change

    NASA Astrophysics Data System (ADS)

    Cooper, Andrew; Green, Andrew

    2014-05-01

    The abundance of beachrocks in the tropics and warm temperate zones renders them a potentially useful indicator of former sea level position. Some studies, however, have expressed doubt with regard to their vertical accuracy, arguing that they form at a range of vertical elevatiosn with respect to former sea level. These criticisms are not, however, coupled with nuanced sedimentological or diagenetic studies of beachrocks. Rather, few beachrock studies take account of such variability and therefore disregard potentially important signatures of the depositional environment. Using detailed case studies, we review the use of beachrocks as Holocene sea level indicators from sites on the continental shelf and contemporary shorelines in southern Africa. We conclude that utilization of detailed sedimentological analysis enhances the utility and vertical reolution of beachrocks as palaeo-sea-level indicators.

  13. Chronology of Fluctuating Sea Levels since the Triassic

    NASA Astrophysics Data System (ADS)

    Haq, Bilal U.; Hardenbol, Jan; Vail, Peter R.

    1987-03-01

    Advances in sequence stratigraphy and the development of depositional models have helped explain the origin of genetically related sedimentary packages during sea level cycles. These concepts have provided the basis for the recognition of sea level events in subsurface data and in outcrops of marine sediments around the world. Knowledge of these events has led to a new generation of Mesozoic and Cenozoic global cycle charts that chronicle the history of sea level fluctuations during the past 250 million years in greater detail than was possible from seismic-stratigraphic data alone. An effort has been made to develop a realistic and accurate time scale and widely applicable chronostratigraphy and to integrate depositional sequences documented in public domain outcrop sections from various basins with this chronostratigraphic frame-work. A description of this approach and an account of the results, illustrated by sea level cycle charts of the Cenozoic, Cretaceous, Jurassic, and Triassic intervals, are presented.

  14. Island biogeography: Shaped by sea-level shifts

    NASA Astrophysics Data System (ADS)

    Fernández-Palacios, José María

    2016-04-01

    An analysis of changes in island topography and climate that have occurred since the last glacial maximum 21,000 years ago shows how sea-level change has influenced the current biodiversity of oceanic islands. See Letter p.99

  15. Tectonic subsidence provides insight into possible coral reef futures under rapid sea-level rise

    NASA Astrophysics Data System (ADS)

    Saunders, Megan I.; Albert, Simon; Roelfsema, Chris M.; Leon, Javier X.; Woodroffe, Colin D.; Phinn, Stuart R.; Mumby, Peter J.

    2016-03-01

    Sea-level rise will change environmental conditions on coral reef flats, which comprise extensive habitats in shallow tropical seas and support a wealth of ecosystem services. Rapid relative sea-level rise of 0.6 m over a relatively pristine coral reef in Solomon Islands, caused by a subduction earthquake in April 2007, generated a unique opportunity to examine in situ coral reef response to relative sea-level rise of the magnitude (but not the rate) anticipated by 2100. Extent of live coral was measured from satellite imagery in 2003, 2006, 2009 and 2012. Ecological data were obtained from microatolls and ecological surveys in May 2013. The reef was sampled at 12 locations where dense live hard coral remained absent, remained present or changed from absent to present following subsidence. Ecological data (substratum depth, live coral canopy depth, coral canopy height, substratum suitability, recruitment, diversity and Acropora presence) were measured at each location to identify factors associated with coral response to relative sea-level rise. Vertical and horizontal proliferation of coral occurred following subsidence. Lateral expansion of live coral, accomplished primarily by branching Acropora spp., resulted in lower diversity in regions which changed composition from pavement to dense live coral following subsidence. Of the ecological factors measured, biotic factors were more influential than abiotic factors; species identity was the most important factor in determining which regions of the reef responded to rapid sea-level rise. On relatively pristine reef flats under present climatic conditions, rapid relative sea-level rise generated an opportunity for hard coral to proliferate. However, the species assemblage of the existing reef was important in determining response to sea-level change, by providing previously bare substrate with a source of new coral colonies. Degraded reefs with altered species composition and slower coral growth rates may be less able to respond to climate change-induced sea-level changes.

  16. Regional sea level change in the Thailand-Indonesia region

    NASA Astrophysics Data System (ADS)

    Fenoglio-Marc, L.; Becker, M. H.; Buchhaupt, C.

    2013-12-01

    It is expected that the regional sea level rise will strongly affect particular regions with direct impacts including submergence of coastal zones, rising water tables and salt intrusion into groundwaters. It can possibly also exacerbate other factors as floodings, associated to storms and hurricanes, as well as ground subsidence of anthropogenic nature. The Thailand-Vietnam-Indonesian region is one of those zones. On land, the Chao-Praya and Mekong Delta are fertile alluvial zones. The potential for sea level increases and extreme floodings due to global warming makes the Deltas a place where local, regional, and global environmental changes are converging. We investigate the relative roles of regional and global mechanisms resulting in multidecadal variations and inflections in the rate of sea level change. Altimetry and GRACE data are used to investigate the variation of land floodings. The land surface water extent is evaluated at 25 km sampling intervals over fifteen years (1993-2007) using a multisatellite methodology which captures the extent of episodic and seasonal inundations, wetlands, rivers, lakes, and irrigated agriculture, using passive and active (microwaves and visible observations. The regional sea level change is analysed during the period 1993-2012 using satellite altimetry, wind and ocean model data, tide gauge data and GPS. The rates of absolute eustatic sea level rise derived from satellite altimetry through 19-year long precise altimeter observations are in average higher than the global mean rate. Several tide gauge records indicate an even higher sea level rise relative to land. We show that the sea level change is closely linked to the ENSO mode of variability and strongly affected by changes in wind forcing and ocean circulation. We have determined the vertical crustal motion at a given tide gauge location by differencing the tide gauge sea level time-series with an equivalent time-series derived from satellite altimetry and by computing the trend of the differences. This method represents an interesting alternative to the use of collocated GPS at the tide gauge stations when GPS is not available. We find anthropogenic subsidence in Jakarta and in three other tide gauge stations. We conclude that the climate-related sea level trend is here reinforced by vertical land movements of a similar or even larger magnitude and that the impact on coastal areas need to be seriously considered. Sea Level Rise (SLR) from satellite altimetry in 1993-2011 and corresponding Relative Sea Level Rise (RSLR) from tide gauge stations (triangle) in the Indonesia-Thailand region.

  17. Sea-level change following the Marinoan Snowball Earth deglaciation

    NASA Astrophysics Data System (ADS)

    Creveling, J. R.; Mitrovica, J. X.

    2014-12-01

    Cap carbonates are broadly thought to represent marine deposition during the glacioeustatic sea-level rise following a 'Snowball Earth' deglaciation (Hoffman et al., 1998). However, a few syn-deglacial Marinoan stratigraphic successions suggest that regional regression punctuated the deglacial transgression (Hoffman and Macdonald, 2010; Rose and Maloof, 2013). A number of questions about the sign and magnitude of post-Snowball sea-level change arise from stratigraphic studies of Neoproterozoic glaciations. For instance, can a local geological inference of the magnitude of transgression provide a robust estimate of the eustatic (globally averaged) sea-level rise associated with the deglaciation? If not, what is the range of geographic variability in regional sea-level change driven by deglaciation? Is this variability a strong function of the duration of the deglaciation? What circumstances could lead to a regional regression interrupting a glacioeustatic transgression? In this talk, we explore the spatial and temporal variability of post-Marinoan Snowball sea-level change using a gravitationally self-consistent theory that accounts for the gravitational, deformational, and rotational perturbations to sea level on a viscoelastic Earth model. We apply the theory to model a Marinoan Snowball deglaciation across a generalized Ediacaran paleogeography with a synthetic ice sheet distribution. We demonstrate that the sea-level change following a synchronous and rapid (2 kyr) collapse of Snowball ice cover would exhibit significant geographic variability, producing local sea-level records characterized by syn-deglacial sea-level rise, fall and stillstand. Both asynchronous melting and longer-duration deglaciation scenarios (5 - 200 kyr) introduce additional complexity into the predicted timing and geometry of the computed post-glacial sea-level change; these complexities include zones of syn-deglacial regression followed by transgression and the possibility of major transgression (and, thus, deposition) that is not limited to the deglaciation phase. These results suggest that sea-level change recorded by strata capping Snowball glaciogenic units could record a far more complicated trajectory than simple transgression.

  18. Sea level differences across the Gulf Stream and Kuroshio extension

    NASA Technical Reports Server (NTRS)

    Zlotnicki, Victor

    1991-01-01

    The sea level differences between the Sargasso Sea and the slope waters across the Gulf Stream region, averaged between 73 and 61 deg W, and the comparable areas across the Kuroshio extension region, averaged between 143 and 156 deg E, were estimated using the Geosat altimeter data obtained between November 1986 and December 1988. The sea-level differences between the two regions showed a strong correlation between the northwest Atlantic and Pacific, dominated by annual cycles that peak in late-September to mid-October, with about 9 cm (the Gulf Stream region) and about 6.9 cm (Kuroshio region) amplitudes.

  19. A unified sea-level response function to global warming

    NASA Astrophysics Data System (ADS)

    Winkelmann, Ricarda; Mengel, Matthias; Reese, Ronja; Levermann, Anders

    2015-04-01

    Linear response functions provide an alternative to process-based models to project future sea-level rise. They are designed to capture the sea-level response to a certain forcing in a comprehensive manner without relying on the full understanding but comprising all processes involved. Here, we propose one unified sea-level response function to global warming as a synthesis of different response functions of the major contributors: oceanic thermal expansion, ice loss from mountain glaciers as well as ice loss from the two ice-sheets on Greenland and Antarctica both through changes in the surface mass balance and dynamic discharge. Except for surface mass balance changes of the ice sheets which occur instantaneously, each response function is inherently time-dependent and accounts for the fact that past climate change will continue to influence sea-level rise in the future. The proposed functions separately estimate the contributions from the main sea-level components on a centennial time scale. The validity of the approach is assessed by comparing the sea-level estimates obtained via the response functions to observations as well as projections from comprehensive models. Total sea level rise and the observed contributions in the past decades are reasonably well reproduced by our approach. Provided that the underlying dynamic mechanisms do not undergo a qualitative change within the 21st century, the response functions found for the individual components can therefore be merged into a single response function in order to project global sea-level rise for a given global mean temperature anomaly.

  20. Mangrove Retreat with Rising Sea-level, Bermuda

    NASA Astrophysics Data System (ADS)

    Ellison, Joanna C.

    1993-07-01

    Low island mangroves keep up with slow sea-level rise by peat accumulation. Holocene stratigraphic records show that they maintain the same pace as sea-level rise at rates up to 9 cm/100 years. Tide gauge records from Bermuda since 1932 show sea-level rise at a rate of 28 cm/100 years. The largest mangrove area (626 acres) at Hungry Bay has for the last 2000 years been building peat at a rate of 85 to 106 cm/100 years. Retreat of the seaward edge has caused loss of 224 acres of mangroves, commencing in the last few hundred years, with a second dieback between 1900 and 1947, and a third dieback in the last decade. The substrate elevation of the seaward margin of mangroves is below mean sea-level, the normal lower limit for mangroves. Present dieback shows problems of erosion indicating that the Bruun Rule of beach erosion with sea-level rise is also appropriate for mangrove swamps. Stratigraphy shows that before 4000 BP sea-level rose at a rate of 25 cm/100 years, from 4000 to 1000 years BP the rate of sea-level rise declined to 6 cm/100 years during which time mangroves established, and in the last 1000 years there was an increase to 143 cm/100 years, during which time the mangroves died back. This study indicates that low island mangroves will experience problems with the rates of sea-level rise predicted for the next 50 years.

  1. Adapting to Rising Sea Level: A Florida Perspective

    NASA Astrophysics Data System (ADS)

    Parkinson, Randall W.

    2009-07-01

    Global climate change and concomitant rising sea level will have a profound impact on Florida's coastal and marine systems. Sea-level rise will increase erosion of beaches, cause saltwater intrusion into water supplies, inundate coastal marshes and other important habitats, and make coastal property more vulnerable to erosion and flooding. Yet most coastal areas are currently managed under the premise that sea-level rise is not significant and the shorelines are static or can be fixed in place by engineering structures. The new reality of sea-level rise and extreme weather due to climate change requires a new style of planning and management to protect resources and reduce risk to humans. Scientists must: (1) assess existing coastal vulnerability to address short term management issues and (2) model future landscape change and develop sustainable plans to address long term planning and management issues. Furthermore, this information must be effectively transferred to planners, managers, and elected officials to ensure their decisions are based upon the best available information. While there is still some uncertainty regarding the details of rising sea level and climate change, development decisions are being made today which commit public and private investment in real estate and associated infrastructure. With a design life of 30 yrs to 75 yrs or more, many of these investments are on a collision course with rising sea level and the resulting impacts will be significant. In the near term, the utilization of engineering structures may be required, but these are not sustainable and must ultimately yield to "managed withdrawal" programs if higher sea-level elevations or rates of rise are forthcoming. As an initial step towards successful adaptation, coastal management and planning documents (i.e., comprehensive plans) must be revised to include reference to climate change and rising sea-level.

  2. Steric and Mass-Induced Sea Level Variations in the Mediterranean Sea, Revisited

    NASA Astrophysics Data System (ADS)

    Garcia-Garcia, D.; Chao, B. F.; Boy, J.-P.

    2009-04-01

    Observed by radar altimetry satellites such as TOPEX/Poseidon (T/P) and Jason-1/2, the total Sea Level Variations (SLV) are produced by a combination of the steric and mass-induced components. The steric SLV can be computed from in situ measurements of temperature and salinity profiles, or from Ocean General Circulation Models (OGCM) that can assimilate those measurements. Mass-induced SLV can be estimated, since 2002, from Time-Variable Gravity (TVG) measurements by the GRACE satellite mission. This methodology has been successfully applied in estimation of the global ocean mass-induced SLV. However, some difficulties arise when studying semi-enclosed basins due to land aliasing of the GRACE TVG signal. The problem is specially complicated in the Mediterranean Sea as reported in previous studies. We revisit this problem analyzing release 4 of the GRACE data set, which represents a time series 3 times longer than in previous studies, by means of new and more efficient filters to reduce the noise in the high degree and order spherical harmonics coefficients. The seasonal and non-seasonal signals are analyzed. From the comparison of GRACE with altimetry data a general underestimation of the steric term is observed in the OGCMs used.

  3. The effect of global climate change on sea level variations along the Bulgarian Black Sea shore

    SciTech Connect

    Mungov, G.; Vesselinov, V.

    1996-12-31

    Data of long-time sea level records along the Bulgarian Black Sea shore are analyzed from the point of view of the global climate change. The analysis of the extreme levels discovers an increase of their appearance during the last 15 years. Two different periods are studied and the recent increases imply the possibility of changes in the regime of the extreme marine events in the Western Black Sea. The cycles in the mean sea levels and the statistical characteristics of the interannual (seasonal) variations are determined. Trends in the sea level records are studied for three basic periods, according the periods in the annual temperature anomalies of the northern hemisphere: 1924--1943; 1944--1973; 1974--1991. The mean sea level rise has maximum value during the first period and minimum during the last third one. This is explained with the decrease of the water inflow into the sea and some initial disturbances in its water balance due to the global climate change. The influence of the global climate change is studied using multiple regression on global environmental data.

  4. Terrestrial Waters and Sea Level Variations on Interannual Time Scale

    NASA Technical Reports Server (NTRS)

    Llovel, W.; Becker, M.; Cazenave, A.; Jevrejeva, S.; Alkama, R.; Decharme, B.; Douville, H.; Ablain, M.; Beckley, B.

    2011-01-01

    On decadal to multi-decadal time scales, thermal expansion of sea waters and land ice loss are the main contributors to sea level variations. However, modification of the terrestrial water cycle due to climate variability and direct anthropogenic forcing may also affect sea level. For the past decades, variations in land water storage and corresponding effects on sea level cannot be directly estimated from observations because these are almost non-existent at global continental scale. However, global hydrological models developed for atmospheric and climatic studies can be used for estimating total water storage. For the recent years (since mid-2002), terrestrial water storage change can be directly estimated from observations of the GRACE space gravimetry mission. In this study, we analyse the interannual variability of total land water storage, and investigate its contribution to mean sea level variability at interannual time scale. We consider three different periods that, each, depend on data availability: (1) GRACE era (2003-2009), (2) 1993-2003 and (3) 1955-1995. For the GRACE era (period 1), change in land water storage is estimated using different GRACE products over the 33 largest river basins worldwide. For periods 2 and 3, we use outputs from the ISBA-TRIP (Interactions between Soil, Biosphere, and Atmosphere-Total Runoff Integrating Pathways) global hydrological model. For each time span, we compare change in land water storage (expressed in sea level equivalent) to observed mean sea level, either from satellite altimetry (periods 1 and 2) or tide gauge records (period 3). For each data set and each time span, a trend has been removed as we focus on the interannual variability. We show that whatever the period considered, interannual variability of the mean sea level is essentially explained by interannual fluctuations in land water storage, with the largest contributions arising from tropical river basins.

  5. Extending the Instrumental Record of Sea-Level Change: A 1300-Year Sea-Level Record From Eastern Connecticut

    NASA Astrophysics Data System (ADS)

    Donnelly, J. P.; Cleary, P.

    2002-12-01

    The instrumental record of sea-level change in the northeastern United States extends back to the early 20th century and at New York City (NYC) extends back to 1856. These tide gauge records indicate that sea level has risen at a rate of 2.5 to 4 mm/year over the last 100-150 years. Geologic evidence of sea-level change in the region over the last 2,000 years indicates rates of sea-level rise of about 1 mm/year or less. The discordance between the instrumental and geologic records is frequently cited as potentially providing evidence that anthropogenic warming of the climate system has resulted in an increase in the rate of sea-level rise. In order to begin to test the hypothesis that acceleration in the rate of sea-level rise has occurred in the last 150 years due to anthropogenic climate warming, accurate and precise information on the timing of the apparent acceleration in sea-level rise are needed. Here we construct a high-resolution relative sea-level record for the past 1350 years by dating basal salt marsh peat samples above a glacial erratic in a western Connecticut salt marsh. Preservation of marsh vegetation remains in the sediment record that has a narrow vertical habitat range at the upper end of the tidal range provides information on past sea levels. { \\it Spartina patens} (marsh hay) and { \\it Juncus gerardi} (black rush) dominate both the modern marsh and their remains are the major constituent of the marsh sediments and occur in the modern marsh between mean high water (MHW) and mean highest high water. We use the elevation distribution of modern plant communities to estimate the relationship of sediment samples to paleo-mean high water. The chronology is based on 15 radiocarbon ages, supplemented by age estimates derived from the horizons of industrial Pb pollution and pollen indicative of European land clearance. Thirteen of the radiocarbon ages and the Pb and pollen data come from samples taken along a contact between marsh peat and a glacial erratic located in the marsh. Two additional radiocarbon ages were obtained from the basal contacts of two cores taken 600m northwest of the erratic in the same marsh. Because we based our record entirely on basal samples, the samples were not displaced vertically by autocompaction of the peat column. The data show a sea-level rise rate of 1.0 +/- 0.3 mm/year from 700 to 1650 AD. From the middle of the 17th century to the middle of the 19th century the rate of sea-level rise was 0.4 \\pm 1 mm/year indicating that the rate of sea-level rise may have slowed during the Little Ice Age. The tide gauge record from New London, CT indicates a rate of 4.1 mm/year between 1939 and present. Data from the Battery tide gauge at NYC indicates a rate of sea-level rise of about 2.8 mm/year from 1856 to present. The NYC tide gauge record indicates that MHW was about 32 cm below modern MHW (as defined by the National Oceanic and Atmospheric Administration) and matches well with the proxy record of past MHW derived from the marsh sediments. The increase in the rate of sea-level rise to modern levels occurs in the 19th century and most likely in the later half of the 19th century. The timing of the observed sea-level rise rate increase is coincident with the onset of atmospheric warming in the late 19th century and indicates that a link between increases in the rate of sea-level rise and anthropogenic climate warming is possible and even likely.

  6. Orthogonal stack of global tide gauge sea level data

    NASA Technical Reports Server (NTRS)

    Trupin, A.; Wahr, J.

    1990-01-01

    Yearly and monthly tide gauge sea level data from around the globe are fitted to numerically generated equilibrium tidal data to search for the 18.6 year lunar tide and 14 month pole tide. Both tides are clearly evident in the results, and their amplitudes and phases are found to be consistent with a global equilibrium response. Global, monthly sea level data from outside the Baltic sea and Gulf of Bothnia are fitted to global atmospheric pressure data to study the response of the ocean to pressure fluctuations. The response is found to be inverted barometer at periods greater than two months. Global averages of tide gauge data, after correcting for the effects of post glacial rebound on individual station records, reveal an increase in sea level over the last 80 years of between 1.1 mm/yr and 1.9 mm/yr.

  7. Coastal vulnerability assessment of Gulf Islands National Seashore (GUIS) to sea-level rise

    USGS Publications Warehouse

    Pendleton, Elizabeth A.; Hammar-Klose, Erika S.; Thieler, E. Robert; Williams, S. Jeffress

    2004-01-01

    A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within Gulf Islands National Seashore (GUIS) in Mississippi and Florida. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, shoreline change rates, mean tidal range and mean wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The Gulf Islands in Mississippi and Florida consist of stable and washover dominated portions of barrier beach backed by wetland and marsh. The areas likely to be most vulnerable to sea-level rise are those with the highest occurrence of overwash, the highest rates of shoreline change, the gentlest regional coastal slope, and the highest rates of relative sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers.

  8. Sea level changes induced by local winds on the west coast of India

    NASA Astrophysics Data System (ADS)

    Mehra, Prakash; Tsimplis, Michael N.; Prabhudesai, R. G.; Joseph, Antony; Shaw, Andrew G. P.; Somayajulu, Y. K.; Cipollini, Paolo

    2010-08-01

    The contribution of atmospheric pressure and local wind to sea level variability at Goa (West coast of India) for the period 2007-2008 is investigated. Sea level data from a tide gauge are compared with measured local surface meteorological as well as oceanographic data. Multilinear regression analysis is used to resolve the dependence of sea level on various forcing parameters. The multilinear regression analysis performed over approx. 2-year data shows that the local surface meteorological data and water temperature account for the sea level variability only up to 6%. The accounted sea level variability increases to 25%, when the local wind and the surface currents obtained from satellite altimetry in the near vicinity of the study area are incorporated in the regression analysis. The contribution of local wind increases substantially when the regression is performed over a 2-month duration, and it is variable within the year. During the summer monsoon season (May-September), the sea level variability attributable to wind is up to 47% and 75%, respectively, for 2007 and 2008; however, it reduces to <20% during the winter monsoon (November-February) season. A significant part of the variability observed in sea level remains unaccounted for and is attributed to remote forcing.

  9. 50 CFR 665.812 - Sea turtle take mitigation measures.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Sea turtle take mitigation measures. 665... Pacific Pelagic Fisheries § 665.812 Sea turtle take mitigation measures. (a) Possession and use of... sea turtle handling requirements set forth in paragraph (b) of this section. (1) Hawaii...

  10. 50 CFR 665.812 - Sea turtle take mitigation measures.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Sea turtle take mitigation measures. 665... Pacific Pelagic Fisheries § 665.812 Sea turtle take mitigation measures. (a) Possession and use of... sea turtle handling requirements set forth in paragraph (b) of this section. (1) Hawaii...

  11. 50 CFR 665.812 - Sea turtle take mitigation measures.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Sea turtle take mitigation measures. 665... Pacific Pelagic Fisheries § 665.812 Sea turtle take mitigation measures. (a) Possession and use of... sea turtle handling requirements set forth in paragraph (b) of this section. (1) Hawaii...

  12. 50 CFR 665.812 - Sea turtle take mitigation measures.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Sea turtle take mitigation measures. 665... Pacific Pelagic Fisheries § 665.812 Sea turtle take mitigation measures. (a) Possession and use of... sea turtle handling requirements set forth in paragraph (b) of this section. (1) Hawaii...

  13. Satellite Remote Sensing: Passive-Microwave Measurements of Sea Ice

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Satellite passive-microwave measurements of sea ice have provided global or near-global sea ice data for most of the period since the launch of the Nimbus 5 satellite in December 1972, and have done so with horizontal resolutions on the order of 25-50 km and a frequency of every few days. These data have been used to calculate sea ice concentrations (percent areal coverages), sea ice extents, the length of the sea ice season, sea ice temperatures, and sea ice velocities, and to determine the timing of the seasonal onset of melt as well as aspects of the ice-type composition of the sea ice cover. In each case, the calculations are based on the microwave emission characteristics of sea ice and the important contrasts between the microwave emissions of sea ice and those of the surrounding liquid-water medium.

  14. Bivariate wavelet-based clustering of sea-level and atmospheric pressure time series

    NASA Astrophysics Data System (ADS)

    Barbosa, Susana; Gouveia, Sonia; Scotto, Manuel; Alonso, Andres

    2015-04-01

    The atmospheric pressure is responsible for a downward force acting on the sea surface which is compensated, to some extent, by corresponding sea-level variations. The static response of the sea surface can be linearly modelled, a decrease (increase) in atmospheric pressure of 1 mb raising (depressing) sea level by 1 cm. However, the dynamic sea surface response to atmospheric pressure loading, associated with ocean dynamics and wind effects, is scale-dependent and difficult to establish. The present study addresses the co-variability of sea-level and pressure time series in the Baltic Sea from the bivariate analysis of tide gauge and reanalysis records. The time series are normalised by the corresponding standard deviation and the wavelet covariance is computed as a measure of the association between sea-level and pressure across scales. A clustering procedure using a dissimilarity matrix based on the wavelet covariance is then implemented. Different classical clustering techniques, including average, single and complete linkage criteria are applied and the group linkage is selected in order to maximise the dendrogram's goodness-of-fit.

  15. Steric and mass-induced sea level variations in the Mediterranean Sea revisited

    NASA Astrophysics Data System (ADS)

    GarcíA-GarcíA, D.; Chao, B. F.; Boy, J.-P.

    2010-12-01

    The total sea level variation (SLV) is the combination of steric and mass-induced SLV, whose exact shares are key to understanding the oceanic response to climate system changes. Total SLV can be observed by radar altimetry satellites such as TOPEX/POSEIDON and Jason 1/2. The steric SLV can be computed through temperature and salinity profiles from in situ measurements or from ocean general circulation models (OGCM), which can assimilate the said observations. The mass-induced SLV can be estimated from its time-variable gravity (TVG) signals. We revisit this problem in the Mediterranean Sea estimating the observed, steric, and mass-induced SLV, for the latter we analyze the latest TVG data set from the GRACE (Gravity Recovery and Climate Experiment) satellite mission launched in 2002, which is 3.5 times longer than in previous studies, with the application of a two-stage anisotropic filter to reduce the noise in high-degree and -order spherical harmonic coefficients. We confirm that the intra-annual total SLV are only produced by water mass changes, a fact explained in the literature as a result of the wind field around the Gibraltar Strait. The steric SLV estimated from the residual of "altimetry minus GRACE" agrees in phase with that estimated from OGCMs and in situ measurements, although showing a higher amplitude. The net water fluxes through both the straits of Gibraltar and Sicily have also been estimated accordingly.

  16. SeaWIFS Postlaunch Technical Report Series. Volume 13; The SeaWiFS Photometer Revision for Incident Surface Measurement (SeaPRISM) Field Commissioning

    NASA Technical Reports Server (NTRS)

    Hooker, Stanford B. (Editor); Zibordi, Giuseppe; Berthon, Jean-Francois; Bailey, Sean W.; Pietras, Christophe M.; Firestone, Elaine R. (Editor)

    2000-01-01

    This report documents the scientific activities that took place at the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea off the coast of Italy from 2-6 August 1999. The ultimate objective of the field campaign was to evaluate the capabilities of a new instrument called the SeaWiFS Photometer Revision for Incident Surface Measurements (SeaPRISM). SeaPRISM is based on a CE-318 sun photometer made by CIMEL Electronique (Paris, France). The CE-318 is an automated, robotic system which measures the direct sun irradiance plus the sky radiance in the sun plane and in the almucantar plane. The data are transmitted over a satellite link, and this remote operation capability has made the device very useful for atmospheric measurements. The revision to the CE-318 that makes the instrument potentially useful for SeaWiFS calibration and validation activities is to include a capability for measuring the radiance leaving the sea surface in wavelengths suitable for the determination of chlorophyll a concentration. The initial evaluation of this new capability involved above- and in-water measurement protocols. An intercomparison of the water-leaving radiances derived from SeaPRISM and an in-water system showed the overall spectral agreement was approximately 8.6%, but the blue-green channels intercompared at the 5% level. A blue-green band ratio comparison was at the 4% level.

  17. Coastal sea level response to the tropical cyclonic forcing in the northern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Mehra, P.; Soumya, M.; Vethamony, P.; Vijaykumar, K.; Balakrishnan Nair, T. M.; Agarvadekar, Y.; Jyoti, K.; Sudheesh, K.; Luis, R.; Lobo, S.; Harmalkar, B.

    2015-02-01

    The study examines the observed storm-generated sea level variation due to deep depression (event 1: E1) in the Arabian Sea from 26 November to 1 December 2011 and a cyclonic storm "THANE" (event 2: E2) over the Bay of Bengal during 25-31 December 2011. The sea level and surface meteorological measurements collected during these extreme events exhibit strong synoptic disturbances leading to storm surges of up to 43 cm on the west coast and 29 cm on the east coast of India due to E1 and E2. E1 generated sea level oscillations at the measuring stations on the west coast (Ratnagiri, Verem and Karwar) and east coast (Mandapam and Tuticorin) of India with significant energy bands centred at periods of 92, 43 and 23 min. The storm surge is a well-defined peak with a half-amplitude width of 20, 28 and 26 h at Ratnagiri, Verem and Karwar, respectively. However, on the east coast, the sea level oscillations during Thane were similar to those during calm period except for more energy in bands centred at periods of ~ 100, 42 and 24 min at Gopalpur, Gangavaram and Kakinada, respectively. The residual sea levels from tide gauge stations in Arabian Sea have been identified as Kelvin-type surges propagating northwards at a speed of ~ 6.5 m s-1 with a surge peak of almost constant amplitude. Multi-linear regression analysis shows that the local surface meteorological data (daily mean wind and atmospheric pressure) is able to account for ~ 57 and ~ 69% of daily mean sea level variability along the east and west coasts of India. The remaining part of the variability observed in the sea level may be attributed to local coastal currents and remote forcing.

  18. Response of the Mediterranean and Dead Sea coastal aquifers to sea level variations

    NASA Astrophysics Data System (ADS)

    Yechieli, Y.; Shalev, E.; Wollman, S.; Kiro, Y.; Kafri, U.

    2010-12-01

    The present study examines the response of groundwater systems to expected changes in the Mediterranean Sea (rise of <1cm/yr) and Dead Sea levels (decline of ˜1 m/yr). A fast response is observed in the Dead Sea coastal aquifer, exhibited both in the drop of the water levels and in the location of the fresh-saline water interface. No such effect is yet observed in the Mediterranean coastal aquifer, as expected. Numerical simulations, using the FeFlow software, show that the effect of global sea level rise depends on the coastal topography next to the shoreline. A slope of 2.5‰ is expected to yield a shift of the interface by 400 m, after a rise of 1m (˜100 years), whereas a vertical slope will yield no shift. Reduced recharge due to climate change or overexploitation of groundwater also enhances the inland shift of the interface.

  19. Historical high-resolution dynamic sea level variations

    NASA Astrophysics Data System (ADS)

    Brunnabend, Sandra-Esther; Dijkstra, Henk A.; Kliphuis, Michael; van Werkhoven, Ben; Bal, Henri E.; Maassen, Jason; van Meersbergen, Maarten; Seinstra, Frank

    2014-05-01

    To investigate future changes in the dynamics of the ocean and therefore in dynamic sea level, ocean models need to be able to adequately represent oceanic dynamical processes. Therefore, resolving ocean eddies and representing boundary currents is of major importance. In this study, we investigate historical variations in dynamical sea surface height using the strongly eddying global version of the Parallel Ocean Program (POP). First, differences in high and low-resolution ocean model results (0.1 vs. 1.0 degree) were analyzed using a climatological atmospheric forcing dataset. Second, we forced the high-resolution model by atmospheric conditions over the period from 1950 to 2000 that are derived from a simulation using the ECHAM5-OM1 model (within the ESSENCE project, see www.knmi.nl/~sterl/Essence/). In general, the large-scale ocean fields of the POP model simulation agree well with those of the low-resolution ocean model (MPI-OM) results. Variations occur due to the different models used and, especially, due to the capability of the high-resolution POP model to resolve eddies. A comparison of high-resolution ocean model results with in-situ measurements, such as dynamic topography provided by altimetry, and salinity and temperature provided by the WOA2013, also show good agreement.

  20. Absolute sea level determination for the subtropical Atlantic Climate Study

    NASA Astrophysics Data System (ADS)

    Saxena, Narendra K.

    1984-03-01

    The Subtropical Atlantic Climate Study (STACS) is a subprogram in the NOAA climate program designed to access the feasibility of monitoring horizontal fluxes in the Gulf Stream system off Florida. Transport in the Florida Current fluctuates on time scales which are reflected in sea level records monitored at tide gauges. Geodetic leveling, connecting tide gauges along the east coast of the United States, allows intercomparison of sea level records alongstream, but the cross-stream and alongstream records in the Bahamas and Cuba are not connected. In this study, various methods to determine absolute sea level differences across the Straits of Florida between Miami, Florida and Cat Cay, Bahamas, a part of the STACS area, were investigated; the desired accuracy of the sea level difference is ± 1 cm. This study indicates that a combination of dense gravity data with satellite altimeter (TOPEX and GEOSAT) data in the STACS area could provide a ± 1 cm absolute sea level difference accuracy across the Straits of Florida. This paper also provides discussion of other conventional methods.

  1. Late Quaternary sea-level changes of the Persian Gulf

    NASA Astrophysics Data System (ADS)

    Lokier, Stephen W.; Bateman, Mark D.; Larkin, Nigel R.; Rye, Philip; Stewart, John R.

    2015-07-01

    Late Quaternary reflooding of the Persian Gulf climaxed with the mid-Holocene highstand previously variously dated between 6 and 3.4 ka. Examination of the stratigraphic and paleoenvironmental context of a mid-Holocene whale beaching allows us to accurately constrain the timing of the transgressive, highstand and regressive phases of the mid- to late Holocene sea-level highstand in the Persian Gulf. Mid-Holocene transgression of the Gulf surpassed today's sea level by 7100-6890 cal yr BP, attaining a highstand of > 1 m above current sea level shortly after 5290-4570 cal yr BP before falling back to current levels by 1440-1170 cal yr BP. The cetacean beached into an intertidal hardground pond during the transgressive phase (5300-4960 cal yr BP) with continued transgression interring the skeleton in shallow-subtidal sediments. Subsequent relative sea-level fall produced a forced regression with consequent progradation of the coastal system. These new ages refine previously reported timings for the mid- to late Holocene sea-level highstand published for other regions. By so doing, they allow us to constrain the timing of this correlatable global eustatic event more accurately.

  2. History of Aral Sea level variability and current scientific debates

    NASA Astrophysics Data System (ADS)

    Cretaux, Jean-François; Letolle, René; Bergé-Nguyen, Muriel

    2013-11-01

    The Aral Sea has shrunk drastically over the past 50 years, largely due to water abstraction from the Amu Darya and Syr Darya rivers for land irrigation. Over a longer timescale, Holocene palaeolimnological reconstruction of variability in water levels of the Aral Sea since 11,700 BP indicates a long history of alternating phases of regression and transgression, which have been attributed variously to climate, tectonic and anthropogenic forcing. The hydrological history of the Aral Sea has been investigated by application of a variety of scientific approaches, including archaeology, palaeolimnological palaeoclimate reconstruction, geophysics, sedimentology, and more recently, space science. Many issues concerning lake level variability over the Holocene and more recent timescales, and the processes that drive the changes, are still a matter for active debate. Our aim in this article is to review the current debates regarding key issues surrounding the causes and magnitude of Aral Sea level variability on a variety of timescales from months to thousands of years. Many researchers have shown that the main driving force of Aral Sea regressions and transgressions is climate change, while other authors have argued that anthropogenic forcing is the main cause of Aral Sea water level variations over the Holocene. Particular emphasis is made on contributions from satellite remote sensing data in order to improve our understanding of the influence of groundwater on the current hydrological water budget of the Aral Sea since 2005. Over this period of time, water balance computation has been performed and has shown that the underground water inflow to the Aral Sea is close to zero with an uncertainty of 3 km3/year.

  3. First order sea-level cycles and supercontinent break up

    SciTech Connect

    Heller, P.L.; Angevine, C.L.

    1985-01-01

    The authors have developed a model that successfully predicts the approximate magnitude and timing of long term sea-level change without relying on short term increases in global spreading rates. The model involves the following key assumptions. (1) Ocean basins have two types of area/age distributions; Pacific ocean basins are rimmed by subduction zones and have triangular distributions; and Atlantic ocean basins which open at constant rates, have no subduction, and so have rectangular distributions. (2) The total area of the global ocean is constant so that the Pacific basin must close as the Atlantic opens. These assumptions approximate modern global ocean basin conditions. The model begins with supercontinent break up. As the Atlantic begins to open, the mean age of the global ocean decreases, the mean depth of the sea floor shallows, and sea level, therefore, rises. Once the Atlantic occupies more than 8 to 10% of the global ocean area, the mean age and depth of the ocean floor increases resulting in a sea-level fall. The model can be applied to the mid-Cretaceous sea-level high stand which followed break up of Pangea by 80 to 100 Ma. Based on average Atlantic opening rates, sea level rises to a peak of 44 m at 80 Ma after opening began and then falls by 84 m to the present. Thus the model is capable of explaining approximately half of the total magnitude of the post-mid-Cretaceous eustatic fall without invoking short-term changes in global spreading rates. In addition, the model predicts the observed time lag between supercontinent break up and sea-level high stand for both Mesozoic as well as early Paleozoic time.

  4. Sea level trend and variability around the Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Luu, Q. H.; Tkalich, P.; Tay, T. W.

    2014-06-01

    Peninsular Malaysia is bounded from the west by Malacca Strait and the Andaman Sea both connected to the Indian Ocean, and from the east by South China Sea being largest marginal sea in the Pacific Basin. Resulting sea level along Peninsular Malaysia coast is assumed to be governed by various regional phenomena associated with the adjacent parts of the Indian and Pacific Oceans. At annual scale, sea level anomalies (SLAs) are generated by the Asian monsoon; interannual sea level variability is determined by the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD); while long-term sea level trend is related to global climate change. To quantify the relative impacts of these multi-scale phenomena on sea level trend and variability around the Peninsular Malaysia, long-term tide gauge record and satellite altimetry are used. During 1984-2011, relative sea level rise (SLR) rates in waters of Malacca Strait and eastern Peninsular Malaysia are found to be 2.4 ± 1.6 mm yr-1 and 2.7 ± 1.0 mm yr-1, respectively. Allowing for corresponding vertical land movements (VLM; 0.8 ± 2.6 mm yr-1 and 0.9 ± 2.2 mm yr-1), their absolute SLR rates are 3.2 ± 4.2 mm yr-1 and 3.6 ± 3.2 mm yr-1, respectively. For the common period 1993-2009, absolute SLR rates obtained from both tide gauge and satellite altimetry in Peninsular Malaysia are similar; and they are slightly higher than the global tendency. It further underlines that VLM should be taken into account to get better estimates of SLR observations. At interannual scale, ENSO affects sea level over the Malaysian coast in the range of ±5 cm with a very high correlation. Meanwhile, IOD modulates sea level anomalies mainly in the Malacca Strait in the range of ±2 cm with a high correlation coefficient. Interannual regional sea level drops are associated with El Niño events and positive phases of the IOD index; while the rises are correlated with La Niña episodes and the negative periods of the IOD index. Seasonally, SLAs are mainly monsoon-driven, in the order of 10-25 cm. Geographically, sea level responds differently to the monsoon: two cycles per year are observed in the Malacca Strait, presumably due to South Asian-Indian Monsoon; whereas single annual cycle is noted along east coast of Peninsular Malaysia, mostly due to East Asian-Western Pacific Monsoon. These results imply that a narrow topographic constriction in Singapore Strait may separate different modes of annual and interannual sea level variability along coastline of Peninsular Malaysia.

  5. A decade of sea level rise slowed by climate-driven hydrology

    NASA Astrophysics Data System (ADS)

    Reager, J. T.; Gardner, A. S.; Famiglietti, J. S.; Wiese, D. N.; Eicker, A.; Lo, M.-H.

    2016-02-01

    Climate-driven changes in land water storage and their contributions to sea level rise have been absent from Intergovernmental Panel on Climate Change sea level budgets owing to observational challenges. Recent advances in satellite measurement of time-variable gravity combined with reconciled global glacier loss estimates enable a disaggregation of continental land mass changes and a quantification of this term. We found that between 2002 and 2014, climate variability resulted in an additional 3200 ± 900 gigatons of water being stored on land. This gain partially offset water losses from ice sheets, glaciers, and groundwater pumping, slowing the rate of sea level rise by 0.71 ± 0.20 millimeters per year. These findings highlight the importance of climate-driven changes in hydrology when assigning attribution to decadal changes in sea level.

  6. A decade of sea level rise slowed by climate-driven hydrology.

    PubMed

    Reager, J T; Gardner, A S; Famiglietti, J S; Wiese, D N; Eicker, A; Lo, M-H

    2016-02-12

    Climate-driven changes in land water storage and their contributions to sea level rise have been absent from Intergovernmental Panel on Climate Change sea level budgets owing to observational challenges. Recent advances in satellite measurement of time-variable gravity combined with reconciled global glacier loss estimates enable a disaggregation of continental land mass changes and a quantification of this term. We found that between 2002 and 2014, climate variability resulted in an additional 3200 ± 900 gigatons of water being stored on land. This gain partially offset water losses from ice sheets, glaciers, and groundwater pumping, slowing the rate of sea level rise by 0.71 ± 0.20 millimeters per year. These findings highlight the importance of climate-driven changes in hydrology when assigning attribution to decadal changes in sea level. PMID:26912856

  7. Global mean sea level - Indicator of climate change

    NASA Technical Reports Server (NTRS)

    Robock, A.; Hansen, J.; Gornitz, V.; Lebedeff, S.; Moore, E.; Etkins, R.; Epstein, E.

    1983-01-01

    A critical discussion is presented on the use by Etkins and Epstein (1982) of combined surface air temperature and sea level time series to draw conclusions concerning the discharge of the polar ice sheets. It is objected by Robock that they used Northern Hemisphere land surface air temperature records which are unrepresentative of global sea surface temperature, and he suggests that externally imposed volcanic dust and CO2 forcings can adequately account for observed temperature changes over the last century, with global sea level changing in passive response to sea change as a result of thermal expansion. Hansen et al. adduce evidence for global cooling due to ice discharge that has not exceeded a few hundredths of a degree centigrade in the last century, precluding any importance of this phenomenon in the interpretation of global mean temperature trends for this period. Etkins and Epstein reply that since their 1982 report additional evidence has emerged for the hypothesis that the polar ice caps are diminishing. It is reasserted that each of the indices discussed, including global mean sea surface temperature and sea level, polar ice sheet mass balance, water mass characteristics, and the spin rate and axis of rotation displacement of the earth, are physically linked and can be systematically monitored, as is currently being planned under the auspices of the National Climate Program.

  8. Do we have to take an acceleration of sea level rise into account?

    NASA Astrophysics Data System (ADS)

    Dillingh, D.; Baart, F.; de Ronde, J.

    2012-04-01

    In view of preservation of safety against inundation and of the many values and functions of the coastal zone, coastal retreat is no longer acceptable. That is why it was decided to maintain the Dutch coastline on its position in 1990. Later the preservation concept was extended to the Dutch coastal foundation, which is the area that encompasses all dune area's and hard sea defences and reaches seawards until the 20m depth contour line. Present Dutch coastal policy is to grow with sea level by means of sand nourishments. A main issue for the planning of sand nourishments is the rate of sea level rise, because that is the main parameter for the volume of the sand needed. The question is than relevant if we already have to take into account an acceleration of sea level rise. Six stations with long water level records, well spread along the Dutch coast, were analysed. Correction of the measured data was considered necessary for an adaptation of the NAP in 2005 as a consequence of movements of the top of the pleistoceen, on which the NAP bench marks have been founded, and for the 18.6 year (nodal) cycle in the time series of yearly mean sea levels. It has been concluded that along the Dutch coast no significant acceleration of sea level rise could be detected yet. Over the last 120 years sea level rose with an average speed of 19 cm per century relative to NAP (the Dutch ordnance datum). Time series shorter than about 50 years showed less robust estimates of sea level rise. Future sea level rise also needs consideration in view of the estimate of future sand nourishment volumes. Scenario's for sea level rise have been derived for the years 2050 and 2100 relative to 1990 by the KNMI (Dutch Met Office) in 2006 for the Dutch situation. Plausible curves have been drawn from 1990 tangent to the linear regression line in 1990 and forced through the high and low scenario projections for 2050 and 2100. These curves show discrepancies with measurements of the last decade, particularly for the high scenario. Dutch design levels for coastal water defence structures (dikes and dunes) are based on extreme value statistics of long time series of high water levels. These design levels have typically return periods of 2000, 4000 and 10.000 years, depending on the importance of the protected dike ring. The last statistical analysis for the update of the design levels refers to the sea level situation of 1985. According to the Water Act Dutch design levels must be tested periodically (every 6 years). Due to sea level rise and tidal changes the design levels are corrected for the rise of the mean high waters from 1985 until the end of the testing period under consideration. This demands a tailoring approach for different regions or locations instead of a national average as for coastal preservation. Runs with climate models and coupled hydrodynamic models in the framework of the Essence project and the Delta Committee 2008 showed no indication for a change in the statistics of extreme storm surge levels. For the estimation of sea level rise over the last 120 years a linear regression gives the most robust estimate. Showing decadal variability needs more sophisticated models. For the last update of the design levels the elegant Whittaker smoother has been applied. Dutch policy prescribes to account for a future sea level rise of 60 cm per century for the design of new dikes or dike reinforcements and 85 cm per century for the long term (200 years) allocation of space for future reinforcements, in agreement with the KNMI'06 scenario's for sea level rise (central value and upper limit).

  9. A full coupled ice-sheet -- sea-level model: relative sea level simulations over the last glacial cycle

    NASA Astrophysics Data System (ADS)

    de Boer, B.; Stocchi, P.; Vandewal, R.

    2014-12-01

    Relative sea-level variations during the late Pleistocene can only be reconstructed with the knowledge of ice-sheet history. On the other hand, the knowledge of regional and global relative sea-level variations is necessary to learn about the changes in ice volume. Overcoming this problem of circularity demands a fully coupled system where ice sheets and sea level vary consistently in space and time and dynamically affect each other. Here we present results for the last glacial cycle from the coupling of a set of 3-D ice-sheet-shelf models to a global sea-level model based on the solution of the gravitationally self-consistent sea-level equation. The sea-level model incorporates all the glacial isostatic adjustment feedbacks for a Maxwell viscoelastic and rotating Earth model with variable coastlines. Ice volume is computed with four 3-D ice-sheet-shelf models for North America, Eurasia, Greenland and Antarctica. With an inverse approach, ice volume and temperature are derived from a benthic δ18O stacked record. The derived surface-air temperature anomaly is applied on the present-day climatology to simulate glacial-interglacial changes in temperature and hence ice volume. The ice-sheet thickness variations are forwarded to the sea-level model to compute the bedrock deformation, the change in sea-surface height and thus the relative sea-level change. The latter is coupled back to the ice-sheet models. Due to rotational effects, local isostatic depression and growth or collapse of the forebulge, RSL differences can reach up to 100 m between different locations over the globe. Additionally, ice-sheet model parameters have been varied such that we come up with a suite of different modelling results of ice volume and accompanying global RSL over the last glacial cycle. Subsequently, we will present a first-order comparison of our results with RSL reconstructions derived from geological and archaeological paleo sea-level indicators over the globe.

  10. Sea-level trends and physical consequences: applications to the U.S. shore

    NASA Astrophysics Data System (ADS)

    Fletcher, Charles H.

    1992-11-01

    As our knowledge of the potential for future global warming increases, our understanding of the imminent dangers associated with continued, possibly accelerated, sea-level rise increases. Several independent research groups have predicted future sea-level rise on the order of 15 to 50 cm by the middle of next century, and between 30 and 110 cm by 2100. Considering the concentration of coastal populations, and dollar value of industries and developments, these increases in mean sea level pose significant hazards. A linkage exists between sea-level history and climate history, but research has demonstrated that sea level is controlled by a complex interaction of geologic, hydrologic and climatologic factors. Because of insufficient data describing global-scale hydrological phenomena, we lack understanding of the components of sea-level change. Present estimates of the various contributions to trends in sea level do not agree with physical measurements of sea-level history. This hampers our ability to make accurate predictions of sea-level behavior. Sea-level rise implies the future threat of accelerated coastal erosion, increased frequency and severity of structural damage resulting from storms which make landfall, salinization of groundwater resources and estuarine and other aquatic ecosystems, destruction of coastal wetlands leading to severe impacts on coastal marine biologic communities, and significant damage to the infrastructure of coastal cities and other population centers. Federally sponsored study groups have completed a series of specific recommendations dealing with the threat of sea-level rise and appropriate responses by parties concerned with the coastal zone. These describe a policy of planned retreat from the coast on a schedule dictated by natural events and processes. The Federal Emergency Management Agency would delineate coastal hazard zones and provide appropriate planning policies governing future development. Compliance with hazard zone standards would determine landowner participation in the National Flood Insurance Program. Federal, state, local and private interests in coastal lands should respond to the threat of sea-level rise and coastal erosion with innovative land management policies and practices that encourage the establishment of coastal high-risk zones and conversion of these lands to low-risk usage.

  11. Low-level radioactivity measurements in an ocean shellfish matrix.

    PubMed

    Altzitzoglou, T

    2000-03-01

    Reference marine biological samples are necessary to test the performance of the analytical methods employed in surveying and monitoring radioactive materials in the sea. The measurement of artificial and natural radionuclide activity concentrations in ocean shellfish material by nondestructive ultra low-level gamma-ray spectrometry in an underground laboratory is reported. The material analysed, a composite material made of Irish Sea and White Sea mussel and Japan Sea oyster, was prepared by the National Institute of Standards and Technology (NIST). PMID:10724403

  12. Sea Level Rise and Subsidence in the Gulf of Thailand

    NASA Astrophysics Data System (ADS)

    Niemnil, Sommart

    In the Thailand -EC GEO2TECDI-SONG Project we investigate the sea level change and vertical land motion in Thailand. First, Bangkok is situated in river delta and average height is closed to sea level. Second, it is subsiding due to ground water extraction. Third, it is experiencing post-seismic motion due to nearby mega thrust earthquakes and fourth, it suffers from rising of sea levels due to global climate change. This poses a serious threat on Thai society and economy. Before mitigation methods can be devised we aim at charting, qualifying and quantifying all contributing effects by the use of satellite altimetry, GNSS, InSAR techniques and combining results with the in situ observations like tide gauge and with geophysical modeling. Adding GPS based vertical land motion to the tide gauge sea level registration reveals the absolute sea level change, which is nicely confirmed by altimetry. We find an average absolute rise of 3.5 mm/yr + 0.7, but nears mouth of Chao Praya River (Bangkok) and the Mekong delta (Ho Chi Min City), this mounts to 4 to 5 mm/yr, faster than global average. This is reinforced when accounting for the tectonic subsidence that resulted from 2004 9.1Mw Sumatra/Andaman earthquake; from 2005 onwards we find downfall in the order of 10 mm/yr. RADARSAT InSAR analyses show subsidence rates up to 25 mm/yr at many places along coastal Bangkok.

  13. Global sea level trend during 1993-2012

    NASA Astrophysics Data System (ADS)

    Chen, Xianyao; Feng, Ying; Huang, Norden E.

    2014-01-01

    Projection of future sea level change relies on the understanding of present sea-level trend and how it has varied in the past. Here we investigate the global-mean sea level (GMSL) change during 1993-2012 using Empirical Mode Decomposition, in an attempt to distinguish the trend over this period from the interannual variability. It is found that the GMSL rises with the rate of 3.2 ± 0.4 mm/yr during 1993-2003 and started decelerating since 2004 to a rate of 1.8 ± 0.9 mm/yr in 2012. This deceleration is mainly due to the slowdown of ocean thermal expansion in the Pacific during the last decade, as a part of the Pacific decadal-scale variability, while the land-ice melting is accelerating the rise of the global ocean mass-equivalent sea level. Recent rapid recovery of the rising GMSL from its dramatic drop during the 2011 La Niña introduced a large uncertainty in the estimation of the sea level trend, but the decelerated rise of the GMSL appears to be intact.

  14. Impact of sea level rise on tide gate function.

    PubMed

    Walsh, Sean; Miskewitz, Robert

    2013-01-01

    Sea level rise resulting from climate change and land subsidence is expected to severely impact the duration and associated damage resulting from flooding events in tidal communities. These communities must continuously invest resources for the maintenance of existing structures and installation of new flood prevention infrastructure. Tide gates are a common flood prevention structure for low-lying communities in the tidal zone. Tide gates close during incoming tides to prevent inundation from downstream water propagating inland and open during outgoing tides to drain upland areas. Higher downstream mean sea level elevations reduce the effectiveness of tide gates by impacting the hydraulics of the system. This project developed a HEC-RAS and HEC-HMS model of an existing tide gate structure and its upland drainage area in the New Jersey Meadowlands to simulate the impact of rising mean sea level elevations on the tide gate's ability to prevent upstream flooding. Model predictions indicate that sea level rise will reduce the tide gate effectiveness resulting in longer lasting and deeper flood events. The results indicate that there is a critical point in the sea level elevation for this local area, beyond which flooding scenarios become dramatically worse and would have a significantly negative impact on the standard of living and ability to do business in one of the most densely populated areas of America. PMID:23379951

  15. Ice2sea - tackling uncertainty in projections of sea-level rise

    NASA Astrophysics Data System (ADS)

    Vaughan, David

    2013-04-01

    The future security and prosperity of our growing coastal cities and survival of many unique coastal habitats requires scientists to deliver reliable sea-level projections, which will form the basis of protection and adaptation planning for vulnerable coastal regions. Most contributions to sea-level rise can now be predicted with some confidence; the greatest remaining uncertainty lies in the contribution of ice-loss from Antarctica and Greenland. An EU Framework-7 programme, ice2sea, is working to inform the IPCC Fifth Assessment, and provide policy-makers with reliable sea-level projections, taking account of the long response-times of ice sheets and the complex atmospheric and oceanic changes that impact them. The collective efforts of 24 partners in Europe and overseas to the ice2sea have produced projections of the contribution of global glaciers and ice sheets to sea-level rise, using process-based models tied to specific emissions scenarios. These projections are synthesised here, with identification of geographical areas and processes where uncertainty is significantly reduced, and others where potential for future reduction remain urgently required.

  16. New and improved data products from the Permanent Service for Mean Sea Level (PSMSL)

    NASA Astrophysics Data System (ADS)

    Matthews, Andrew; Bradshaw, Elizabeth; Gordon, Kathy; Hibbert, Angela; Jevrejeva, Svetlana; Rickards, Lesley; Tamisiea, Mark; Williams, Simon

    2015-04-01

    The Permanent Service for Mean Sea Level (PSMSL) is the internationally recognised global sea level data bank for long term sea level change information from tide gauges. Established in 1933, the PSMSL continues to be responsible for the collection, publication, analysis and interpretation of sea level data. The PSMSL operates under the auspices of the International Council for Science (ICSU) and is one of the main data centres for both the International Association for the Physical Sciences of the Oceans (IAPSO) and the International Association of Geodesy (IAG). The PSMSL continues to work closely with other members of the sea level community through the Intergovernmental Oceanographic Commission's Global Sea Level Observing System (GLOSS). Currently, the PSMSL data bank for monthly and annual sea level data holds over 65,000 station-years of data from over 2200 stations. Data from each site are carefully quality controlled and, wherever possible, reduced to a common datum, whose stability is monitored through a network of geodetic benchmarks. Last year, the PSMSL also made available a data bank of measurements taken from in-situ ocean bottom pressure recorders from over 60 locations across the globe. Here, we present an overview of the data available at the PSMSL, and describe some of the ongoing work that aims to provide more information to users of our data. In particular, we describe the ongoing work with the Système d'Observation du Niveau des Eaux Littorales (SONEL) to use measurements from continuous GNSS records located near tide gauges to provide PSMSL data within a geocentric reference frame. We also highlight changes to the method used to present estimated sea level trends to account for seasonal cycles and autocorrelation in the data, and provide an estimate of the error of the trend.

  17. How Regional Sea Level Variability Studies can Benefit from Sentinel-3

    NASA Astrophysics Data System (ADS)

    Passaro, Marcello; Cipollini, Paolo; Benveniste, Jerome

    2015-12-01

    Sentinel-3 will provide the research on sea level variability with two key features: 1) high density of repeated tracks and 2) Delay/Doppler processing. This study investigates the benefits from these two features considering previous missions, i.e. Envisat for 1) and Cryosat-2 for 2). The high density of repeated tracks increases the detection of spatial variation in the sea level variability at a sub-regional scale. This is evident in the North-Sea/Baltic Sea transition zone, where the ALES coastal reprocessing of Envisat data highlighted significant variations of the annual signal of the sea level in a 50-100 Km scale. The Delay/Doppler processing was already performed in the framework of Cryosat-2. The analysis of the sea level estimations in the Indonesian Seas demonstrates that Cryosat-2 is able to decrease by roughly 1 cm the high-rate noise of sea level estimation within 50 km of the coast, when compared to the ALES-reprocessed Envisat dataset. Despite the fact that the specific ground-tracks followed by Cryosat-2, which repeat every 369 days, do not follow the ground-tracks of previous altimetry missions, no significant change is seen in the variability if compared to Envisat measurement. The analysis of the sea surface height anomaly differences between Envisat and Cryosat-2 at the crossover points proves that in the region of study a sea state bias correction equal to 5% of the significant wave height is an acceptable approximation for this application.

  18. Mean sea level determination from satellite altimetry

    NASA Technical Reports Server (NTRS)

    Kahn, W. D.; Agrawal, B. B.; Brown, R. D.

    1977-01-01

    The primary experiment on the Geodynamics Experimental Ocean Satellite-3 (GEOS-3) is the radar altimeter. This experiment's major objective is to demonstrate the utility of measuring the geometry of the ocean surface, i.e. the geoid. Results obtained from this experiment so far indicate that the planned objectives of measuring the topography of the ocean surface with an absolute accuracy of + or - 5 meters can be met and perhaps exceeded. The GEOS-3 satellite altimeter measurements have an instrument precision in the range of + or - 25 cm to + or - 50 cm when the altimeter is operating in the short pulse mode.

  19. Concerns--High Sea Levels and Temperatures Seen Next Century.

    ERIC Educational Resources Information Center

    Ryan, Paul R.

    1984-01-01

    A National Research Council committee recently concluded that atmospheric carbon dioxide levels will "most likely" double by late in the next century, causing an increase in the earth's average temperature. Effects of the increase on sea levels, global climate, and other parameters are discussed. (JN)

  20. Regional Sea Level Changes Projected by the NASA/GISS Atmosphere-Ocean Model

    NASA Technical Reports Server (NTRS)

    Russell, Gary L.; Gornitz, Vivien; Miller, James R.

    1999-01-01

    Sea level has been rising for the past century, and inhabitants of the Earth's coastal regions will want to understand and predict future sea level changes. In this study we present results from new simulations of the Goddard Institute for Space Studies (GISS) global atmosphere-ocean model from 1950 to 2099. Model results are compared with observed sea level changes during the past 40 years at 17 coastal stations around the world. Using observed levels of greenhouse gases between 1950 and 1990 and a compounded 0.5% annual increase in Co2 after 1990, model projections show that global sea level measured from 1950 will rise by 61 mm in the year 2000, by 212 mm in 2050, and by 408 mm in 2089. By 2089, two thirds of the global sea level rise will be due to thermal expansion and one third will be due to ocean mass changes. The spatial distribution of sea level rise is different than that projected by rigid lid ocean models.

  1. Rising sea level may cause decline of fringing coral reefs

    USGS Publications Warehouse

    Field, Michael E.; Ogston, Andrea S.; Storlazzi, Curt D.

    2011-01-01

    Coral reefs are major marine ecosystems and critical resources for marine diversity and fisheries. These ecosystems are widely recognized to be at risk from a number of stressors, and added to those in the past several decades is climate change due to anthropogenically driven increases in atmospheric concentrations of greenhouse gases. Most threatening to most coral reefs are elevated sea surface temperatures and increased ocean acidity [e.g., Kleypas et al., 1999; Hoegh-Guldberg et al., 2007], but sea level rise, another consequence of climate change, is also likely to increase sedimentary processes that potentially interfere with photosynthesis, feeding, recruitment, and other key physiological processes (Figure 1). Anderson et al. [2010] argue compellingly that potential hazardous impacts to coastlines from 21st-century sea level rise are greatly underestimated, particularly because of the rapid rate of rise. The Intergovernmental Panel on Climate Change estimates that sea level will rise in the coming century (1990–2090) by 2.2–4.4 millimeters per year, when projected with little contribution from melting ice [Meehl et al., 2007]. New studies indicate that rapid melting of land ice could substantially increase the rate of sea level rise [Grinsted et al., 2009; Milne et al., 2009].

  2. Rising sea level may cause decline of fringing coral reefs

    USGS Publications Warehouse

    Field, M.E.; Ogston, A.S.; Storlazzi, C.D.

    2011-01-01

    Coral reefs are major marine ecosystems and critical resources for marine diversity and fisheries. These ecosystems are widely recognized to be at risk from a number of stressors, and added to those in the past several decades is climate change due to anthropogenically driven increases in atmospheric concentrations of greenhouse gases. Most threatening to most coral reefs are elevated sea surface temperatures and increased ocean acidity [e.g., Kleypas et al., 1999; Hoegh-Guldberg et al., 2007], but sea level rise, another consequence of climate change, is also likely to increase sedimentary processes that potentially interfere with photosynthesis, feeding, recruitment, and other key physiological processes (Figure 1). Anderson et al. [2010] argue compellingly that potential hazardous impacts to coastlines from 21st-century sea level rise are greatly underestimated, particularly because of the rapid rate of rise. The Intergovernmental Panel on Climate Change estimates that sea level will rise in the coming century (1990-2090) by 2.2-4.4 millimeters per year, when projected with little contribution from melting ice [Meehl et al., 2007]. New studies indicate that rapid melting of land ice could substantially increase the rate of sea level rise [Grinsted et al., 2009; Milne et al., 2009].

  3. Facilitating Progress on the Quaternary History of Sea Level Change

    NASA Astrophysics Data System (ADS)

    Thompson, W. G.; Andersen, M. B.

    2010-04-01

    Understanding Future Sea Level Rise: The Challenges of Dating Past Interglacials; Woods Hole, Massachusetts, 20-25 September 2009; Substantial uncertainty exists in projections of future sea level rise, due primarily to a lack of understanding about ice sheet dynamics. Paleo Constraints on Sea Level Rise (PALSEA) is a working group of the Past Global Changes (PAGES) project and the International Marine Global Change Studies (IMAGES) program that aims to extract information about ice sheet response to temperature change by examining the history of sea level over the Quaternary (spanning the past ˜2.5 million years). In particular, PALSEA focuses on the past 800,000 years, particularly interglacial periods, with a range of temperatures bracketing the modern. PALSEA recently held a workshop at Woods Hole Oceanographic Institution (WHOI). Funded by IMAGES, PAGES, and WHOI's Ocean and Climate Change Institute, the workshop focused on challenges in uranium-thorium (U-Th) coral dating. The meeting also included a public outreach event, “Where land and sea meet: Managing shoreline change over the next 100 years,” funded by WHOI's Morss Colloquium.

  4. Rising sea level may cause decline of fringing coral reefs

    NASA Astrophysics Data System (ADS)

    Field, Michael E.; Ogston, Andrea S.; Storlazzi, Curt D.

    2011-08-01

    Coral reefs are major marine ecosystems and critical resources for marine diversity and fisheries. These ecosystems are widely recognized to be at risk from a number of stressors, and added to those in the past several decades is climate change due to anthropogenically driven increases in atmospheric concentrations of greenhouse gases. Most threatening to most coral reefs are elevated sea surface temperatures and increased ocean acidity [e.g., Kleypas et al., 1999; Hoegh-Guldberg et al., 2007], but sea level rise, another consequence of climate change, is also likely to increase sedimentary processes that potentially interfere with photosynthesis, feeding, recruitment, and other key physiological processes (Figure 1). Anderson et al. [2010] argue compellingly that potential hazardous impacts to coastlines from 21st-century sea level rise are greatly underestimated, particularly because of the rapid rate of rise. The Intergovernmental Panel on Climate Change estimates that sea level will rise in the coming century (1990-2090) by 2.2-4.4 millimeters per year, when projected with little contribution from melting ice [Meehl et al., 2007]. New studies indicate that rapid melting of land ice could substantially increase the rate of sea level rise [Grinsted et al., 2009; Milne et al., 2009].

  5. The Significance of Rising Sea Levels.

    ERIC Educational Resources Information Center

    Conway, Gregory J.

    1989-01-01

    Describes an activity in which students graph changes in tides and ocean levels over a period in order to obtain a visual representation of the changes taking place and their effects upon the Earth. Provides questions for students to answer after construction of the graphs. (RT)

  6. The imprint of sea-level changes in the Southeastern Iberian continental shelf, Western Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Pinna, Andrea; Lastras, Galderic; Acosta, Juan; Muñoz, Araceli; Canals, Miquel

    2014-05-01

    A detailed morphologic analysis of the Southeastern Iberian continental shelf, Western Mediterranean Sea, between the Mar Menor and the Gulf of Almería, based on swath bathymetry data, has revealed a number of seafloor features that we attribute to the imprint of sea-level changes since the last glacial maximum. The continental shelf has been divided in four different domains with contrasting characteristics: the Mar Menor sector, the Mazarrón and Vera sector, the Gata Cape shelf and the Gulf of Almería shelf. The Mar Menor sector displays an up to 40 km wide shelf with a very low slope gradient, which contrasts with the Mazarrón and Vera shelf, with a width ranging between 0.4 and 5 km, severely incised by the different branches of the Garrucha submarine canyon. On each of these sectors, a variety of morphologies such as crests and escarpments have been identified. Most of these crests and escarpments can be followed for distances exceeding 15 km, and are located at constant, characteristic water depths. We interpret these structures as the result of relatively short-lived sea-level still-stands and thus as palaeo-coastlines. Taking into account subsidence, we have correlated their bathymetric position with published post-MIS-5 Mediterranean sea-level evolution curves, allowing the attribution of an approximate age for each interpreted palaeo-coastline. The last sea-level regression is partially registered in the smooth Mar Menor shelf, where different crests and escarpments are cut by a LGM palaeo-channel, whereas all the sectors display structures related to the last sea-level transgression. The continuity of these structures along all the sectors has allowed reconstructing the evolution of the coastline during the last sea-level transgression, and thus inferring the palaeo-landscape of this sector of the Southeastern Iberian coast at different stages since 18 ka BP until the present.

  7. Geosat observations of sea level response to barometric pressure forcing

    NASA Technical Reports Server (NTRS)

    Hoar, Timothy J.; Wilson, Clark R.

    1994-01-01

    Altimeter and sea level pressure data from the Geosat mission are analyzed for evidence of inverted barometer responses of sea level to atmospheric pressure forcing. Estimates of the inverted barometer coefficient are given for a variety of geographic regions and time scales using various orbit error removal strategies. There is some sensitivity to the orbit error removal method, but the estimated coefficients show a clear latitudinal dependence and are generally between -0.5 cm/mbar and -0.9 cm/mbar. The southern oceans respond slightly more like an inverted barometer than the northern oceans for similar latitudes. The regression exhibits significant geographic variability, particularly near major circulation features and in the northern hemisphere. The results suggest that the inverted barometer approximation is resonable over much of the oceans, but that some sea level variability may be correlated with barometric pressure by means other than the inverted barometer effect.

  8. Sea Levels during the Past 35,000 Years.

    PubMed

    Milliman, J D; Emery, K O

    1968-12-01

    A sea-level curve of the past 35,000 years for the Atlantic continental shelf of the United States is based on more than 80 radiocarbon dates, 15 of which are older than 15,000 years. Materials include shallow-water mollusks, oolites, coralline algae, beachrock, and salt-marsh peat. Sea level 30,000 to 35,000 years ago was near the present one. Subsequent glacier growth lowered sea level to about -130 meters 16,000 years ago. Holocene transgression probably began about 14,000 years ago, and continued rapidly to about 7000 years ago. Dates from most shelves of the world agree with this curve, suggesting that it is approximately the eustatic curve for the period. PMID:17746818

  9. Modal recovery of sea-level variability in the South China Sea using merged altimeter data

    NASA Astrophysics Data System (ADS)

    Jiang, Haoyu; Chen, Ge

    2015-09-01

    Using 20 years (1993-2012) of merged data recorded by contemporary multi-altimeter missions, a variety of sea-level variability modes are recovered in the South China Sea employing three-dimensional harmonic extraction. In terms of the long-term variation, the South China Sea is estimated to have a rising sea-level linear trend of 5.39 mm/a over these 20 years. Among the modes extracted, the seven most statistically significant periodic or quasi-periodic modes are identified as principal modes. The geographical distributions of the magnitudes and phases of the modes are displayed. In terms of intraannual and annual regimes, two principal modes with strict semiannual and annual periods are found, with the annual variability having the largest amplitudes among the seven modes. For interannual and decadal regimes, five principal modes at approximately 18, 21, 23, 28, and 112 months are found with the most mode-active region being to the east of Vietnam. For the phase distributions, a series of amphidromes are observed as twins, termed "amphidrome twins", comprising rotating dipole systems. The stability of periodic modes is investigated employing joint spatiotemporal analysis of latitude/longitude sections. Results show that all periodic modes are robust, revealing the richness and complexity of sea-level modes in the South China Sea.

  10. Twentieth century sea-level rise inferred from tide gauge, geologically derived and thermosteric sea-level changes

    NASA Astrophysics Data System (ADS)

    Nakada, Masao; Okuno, Jun'ichi; Ishii, Masayoshi

    2013-09-01

    Relative sea-level (RSL) changes at thirteen sites derived from tide gauge and/or salt-marsh sediment sequences, with information for RSL changes during at least the past ˜200 years, are used to infer the rates and causes of the global sea-level rise in the twentieth century (pre-satellite era) by incorporating spatially non-uniform thermosteric sea-level change and recent estimates for the melting of mountain glaciers and both polar ice sheets. The main advantage of the method adopted here is that we can avoid a model-dependence in the GIA (glacial isostatic adjustment) correction and any steady tectonic effect depending on each location can be corrected for. We first estimate the acceleration of sea-level rise in the twentieth century at each RSL observation site, and then evaluate the residuals between the sea-level acceleration and thermosteric sea-level rise. The spatially non-uniform residuals are examined to infer the rates of RSL rise due to the melting of mountain glaciers and polar ice sheets. The comparison between the residuals and the predicted rates for the melting wholly supports the estimates for the melting by the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC 2007 Report), and does not require a significant melting from the Greenland ice sheet. However, the possible equivalent sea-level rise for mountain glaciers and/or Antarctic ice sheet may be ˜0.3 mm yr-1 larger than the preferred estimate by IPCC 2007 Report (˜0.7 mm yr-1), and the total one is ˜1.0 mm yr-1. The additional melting for ˜0.3 mm yr-1 is due to the comparison mainly for Brest with long tide gauge records of ˜200 years. Also, the present study indicates that the global mean thermosteric sea-level rise before the rapid sea-level acceleration occurred at 1990 is ˜0.3 mm yr-1.

  11. Absolute magnitude of the second-order middle to late Miocene sea-level fall, Marion Plateau, northeast Australia

    SciTech Connect

    Pigram, C.J.; Davies, P.J.; Feary, D.A.; Symonds, P.A. )

    1992-09-01

    The Miocene carbonate platform of the Marion Plateau in northeast Australia preserves an excellent record of sea-level fluctuations. The warm-water platform consists of an early to middle Miocene second-order highstand complex, whereas the late Miocene platform is a second-order lowstand complex. Analysis of the sea-level fall that led to this relation shows that the amplitude of this event was at least 180 m. Furthermore, the authors suggest a methodology for determining the amplitude of sea-level fluctuations based on measurement of sea-level falls in structurally simple parts of passive margins or in distal parts of foreland basins.

  12. The sea level budget since 2003; Inference on the deep ocean heat content

    NASA Astrophysics Data System (ADS)

    Dieng, Habib B.; Palanisamy, Hindumathi; Cazenave, Anny; Meyssignac, Benoit; von Schuckmann, Karina

    2015-04-01

    This study provides an overview of the various components of the global mean sea level evolution over two time spans: (1) 2005-2012 (corresponding of full deployment of the Argo program) and (2) 2003-2012. Using a sea level budget approach, we compare altimetry-based global mean sea level, global ocean mass from GRACE space gravimetry and steric sea level from Argo and other in situ measurements. One goal of this study is to investigate whether it is possible to constrain any deep ocean contribution to the global mean sea level rise over the last decade. This question is particularly relevant, considering the current debate about the 'hiatus', i.e. the observed recent pause of the global mean air and sea surface temperature evolution while the planet is still in thermal imbalance. We consider a total of 16 different data sets. Differences are noticed between data sets related to each variable (sea level, ocean mass and steric sea level), mostly due to data processing issues. Therefore we perform the analysis using averages of available data sets. For each period, we find that when removing from the global mean sea level, the contributions of the global mean ocean mass and steric sea level (estimated for the 0-1500 m ocean layer), there remains a residual signal displaying a positive slope of 0.3 +/- 0.6 mm/yr and 0.55 +/- 0.6 mm/yr over 2005-2012 and 2003-2012 respectively. Comparing with an ocean reanalysis and according to direct (but sparse) ocean temperature measurements below 1500 m, it seems unlikely that the observed residual signal can be attributed to deep (below 1500m) ocean warming, in agreement with other recently published results. More likely, we estimate that it reflects, at least partly, the signature of missing upper ocean steric signal in regions uncovered by current observing systems. Our study also shows a steady warming increase since 2003 of the 700-1500 m ocean layers (amounting 0.2 mm/yr in steric sea level equivalent), confirming previous findings, but seen in our study in each of the eight different steric data sets considered.

  13. The Sea Level Budget Since 2003: Inference on the Deep Ocean Heat Content

    NASA Astrophysics Data System (ADS)

    Dieng, Habib B.; Palanisamy, Hindumathi; Cazenave, Anny; Meyssignac, Benoit; von Schuckmann, Karina

    2015-03-01

    This study provides an overview of the various components of the global mean sea level evolution over two time spans: (1) 2005-2012 (corresponding to the full deployment of the Argo program) and (2) 2003-2012. Using a sea level budget approach, we compare altimetry-based global mean sea level, global ocean mass from GRACE space gravimetry and steric sea level from Argo and other in situ measurements. One goal of this study is to investigate whether it is possible to constrain the deep ocean contribution to the global mean sea level rise over the last decade. This question is particularly relevant, considering the current debate about the `hiatus,' i.e., the observed recent pause of the global mean air and sea surface temperature evolution while the planet is still in thermal imbalance. We consider a total of 16 different data sets. Differences are noticed between data sets related to each variable (sea level, ocean mass and steric sea level), mostly due to data processing issues. Therefore, we perform the analysis using averages of the available data sets. For each period, we find that, when removing from the global mean sea level, the contributions of the global mean ocean mass and steric sea level (estimated for the 0-1,500 m ocean layer), there remains a residual signal displaying a positive slope of 0.3 ± 0.6 and 0.55 ± 0.6 mm/year over 2005-2012 and 2003-2012, respectively. Comparing with an ocean reanalysis and according to direct (but sparse) ocean temperature measurements below 1,500 m, it seems unlikely that the observed residual signal can be attributed to deep (below 1,500 m) ocean warming, in agreement with other recently published results. We estimate that it possibly reflects, at least partly, the signature of a missing upper ocean steric signal in regions uncovered by current observing systems. Our study also shows a steady warming increase since 2003 of the 700-1,500 m ocean layer (amounting ~0.2 mm/year in steric sea level equivalent), confirming previous findings, but seen in our study in each of the eight different steric data sets considered.

  14. A unique asymmetry in the pattern of recent sea level change

    NASA Astrophysics Data System (ADS)

    Thompson, Philip R.; Merrifield, Mark A.

    2014-11-01

    The spatial pattern of 20 year sea surface height trends from satellite altimetry is placed into the context of historical modes of wind-driven ocean volume redistribution identified in basin-scale, regional averages of tide gauge data. The difference between recent rates of sea level change in northern and southern regions is found to be twice as large and statistically greater than any other 20 year period during the twentieth century. This unique asymmetry in the pattern of sea level change coincides with a departure from a historical mode of volume redistribution between southern regions related to a measure of asymmetry in the Southern Annular Mode. The asymmetry also coincides with a maximum in the rate of global mean sea level rise during recent decades, but the asymmetry is not apparent during an early twentieth century maximum in the global rate of similar magnitude.

  15. Longitudinal development of muons in large air showers studies from the arrival time distributions measured at 900m above sea level

    NASA Technical Reports Server (NTRS)

    Kakimoto, F.; Tsuchimoto, I.; Enoki, T.; Suga, K.; Nishi, K.

    1985-01-01

    The arrival time distributions of muons with energies above 1.0GeV and 0.5GeV have been measured in the Akeno air-shower array to study the longitudinal development of muons in air showers with primary energies in the range 10 to the 17th power to 10 to the 18th power ev. The average rise times of muons with energies above 1.0GeV at large core distances are consistent with those expected from very high multiplicity models and, on the contrary, with those expected from the low multiplicity models at small core distances. This implies that the longitudinal development at atmospheric depth smaller than 500 cm square is very fast and that at larger atmospheric depths is rather slow.

  16. Revisiting the role of CH4 emissions from alpine wetlands on the Tibetan Plateau: Evidence from two in situ measurements at 4758 and 4320 m above sea level

    NASA Astrophysics Data System (ADS)

    Wei, Da; Xu-Ri; Tarchen, Tenzin; Dai, Dongxue; Wang, Yuesi; Wang, Yinghong

    2015-09-01

    The alpine wetlands on the Tibetan Plateau (TP) constitute 30% of China's wetlands, and previous studies have considered these wetlands to be important sources of CH4, based on several swamp measurements from the eastern edges of the plateau. However, the alpine wetlands consist of both swamps (9.5%) and swamp meadows (79.8%). In this study, the CH4 fluxes of a swamp meadow and a swamp were determined. The results showed that the swamp meadow emitted much less CH4 (130.8 ± 123.9 µg m-2 h-1) than the swamp (2795.2 ± 796.4 µg m-2 h-1). The CH4 fluxes within the swamp meadow showed distinct microscale spatial heterogeneity: the hollow terrain released CH4, while the hummocks absorbed CH4; this pattern was explained well by soil moisture. The CH4 emissions in the swamp meadow were highly sensitive to soil temperature variation (Q10 = 3.62), while they were more sensitive to soil moisture in the swamp. By summarizing existing measurements, and considering the differences in CH4 emissions from swamp meadows and swamps, the emissions of CH4 from alpine wetlands across the TP were recalculated to range from 0.215 to 0.412 Tg CH4 a-1, lower than previous studies. By comparison, the CH4 uptake by nonwetland ecosystems ranges from -0.68 to -0.53 Tg CH4 a-1. Therefore, this study conveys a notion that the alpine wetlands on the TP may not be significant CH4 sources. However, further studies are needed to reduce the uncertainty regarding CH4 emissions.

  17. Investigation of sea level trends and the effect of the north atlantic oscillation (NAO) on the black sea and the eastern mediterranean sea

    NASA Astrophysics Data System (ADS)

    Ozgenc Aksoy, Aysegul

    2016-03-01

    The North Atlantic Oscillation (NAO) has significant effects on sea levels, weather, and climate. In this study, the sea level trends and the effects of the North Atlantic Oscillation Indices (NAOI) on annual mean sea level data were assessed for the Black Sea and the Eastern Mediterranean Sea. The trends of sea level and NAOI were determined using Mann-Kendall dimensionless z statistics. Generally, upward sea level trends were detected for the Black Sea and the Eastern Mediterranean Sea. In the Black Sea, significant and continuous upward trends were detected after the year 1950. Weaker trends were detected for the Eastern part of the Mediterranean Sea. Sea level trends were correlated with trends in NAO indices; negative correlations were detected for the Black Sea, whereas positive correlations were found for the Eastern Mediterranean Sea. Paired t tests were performed to determine the turning points for all sea level data sets. The value of t was positive for all data sets, which means that the mean value of the data set before the turning point was smaller than the mean value of the data set after the turning point.

  18. Coastal flooding by tropical cyclones and sea-level rise.

    PubMed

    Woodruff, Jonathan D; Irish, Jennifer L; Camargo, Suzana J

    2013-12-01

    The future impacts of climate change on landfalling tropical cyclones are unclear. Regardless of this uncertainty, flooding by tropical cyclones will increase as a result of accelerated sea-level rise. Under similar rates of rapid sea-level rise during the early Holocene epoch most low-lying sedimentary coastlines were generally much less resilient to storm impacts. Society must learn to live with a rapidly evolving shoreline that is increasingly prone to flooding from tropical cyclones. These impacts can be mitigated partly with adaptive strategies, which include careful stewardship of sediments and reductions in human-induced land subsidence. PMID:24305147

  19. Coastal flooding by tropical cyclones and sea-level rise

    NASA Astrophysics Data System (ADS)

    Woodruff, Jonathan D.; Irish, Jennifer L.; Camargo, Suzana J.

    2013-12-01

    The future impacts of climate change on landfalling tropical cyclones are unclear. Regardless of this uncertainty, flooding by tropical cyclones will increase as a result of accelerated sea-level rise. Under similar rates of rapid sea-level rise during the early Holocene epoch most low-lying sedimentary coastlines were generally much less resilient to storm impacts. Society must learn to live with a rapidly evolving shoreline that is increasingly prone to flooding from tropical cyclones. These impacts can be mitigated partly with adaptive strategies, which include careful stewardship of sediments and reductions in human-induced land subsidence.

  20. The Impact of Sea Level Rise on Florida's Everglades

    NASA Astrophysics Data System (ADS)

    Senarath, S. U.

    2005-12-01

    Global warming and the resulting melting of polar ice sheets could increase global sea levels significantly. Some studies have predicted mean sea level increases in the order of six inches to one foot in the next 25 to 50 years. This could have severe irreversible impacts on low-lying areas of Florida's Everglades. The key objective of this study is to evaluate the effects of a one foot sea level rise on Cape Sable Seaside Sparrow (CSSS) nesting areas within the Everglades National Park (ENP). A regional-scale hydrologic model is used to assess the sensitivities of this sea-level rise scenario. Florida's Everglades supports a unique ecosystem. At present, about 50 percent of this unique ecosystem has been lost due to urbanization and farming. Today, the water flow in the remnant Everglades is also regulated to meet a variety of competing environmental, water-supply and flood-control needs. A 30-year, eight billion dollar (1999 estimate) project has been initiated to improve Everglades' water flows. The expected benefits of this restoration project will be short-lived if the predicted sea level rise causes severe impacts on the environmentally sensitive areas of the Everglades. Florida's Everglades is home to many threatened and endangered species of wildlife. The Cape Sable Seaside Sparrow population in the ENP is one such species that is currently listed as endangered. Since these birds build their nests close to the ground surface (the base of the nest is approximately six inches from the ground surface), they are directly affected by any sea level induced ponding depth, frequency or duration change. Therefore, the CSSS population serves as a good indicator species for evaluating the negative impacts of sea level rise on the Everglades' ecosystem. The impact of sea level rise on the CSSS habitat is evaluated using the Regional Simulation Model (RSM) developed by the South Florida Water Management District. The RSM is an implicit, finite-volume, continuous, distributed, and integrated surface-water and ground-water model. It can simulate one-dimensional canal/stream flow and two-dimensional overland and groundwater flow in arbitrarily shaped areas using a variable triangular mesh. The overland and groundwater flow components are fully coupled in the RSM for a more realistic representation of runoff generation.

  1. Improved sea level record over the satellite altimetry era (1993-2010) from the Climate Change Initiative project

    NASA Astrophysics Data System (ADS)

    Ablain, M.; Cazenave, A.; Larnicol, G.; Balmaseda, M.; Cipollini, P.; Faugère, Y.; Fernandes, M. J.; Henry, O.; Johannessen, J. A.; Knudsen, P.; Andersen, O.; Legeais, J.; Meyssignac, B.; Picot, N.; Roca, M.; Rudenko, S.; Scharffenberg, M. G.; Stammer, D.; Timms, G.; Benveniste, J.

    2015-01-01

    Sea level is one of the 50 Essential Climate Variables (ECVs) listed by the Global Climate Observing System (GCOS) in climate change monitoring. In the past two decades, sea level has been routinely measured from space using satellite altimetry techniques. In order to address a number of important scientific questions such as "Is sea level rise accelerating?", "Can we close the sea level budget?", "What are the causes of the regional and interannual variability?", "Can we already detect the anthropogenic forcing signature and separate it from the internal/natural climate variability?", and "What are the coastal impacts of sea level rise?", the accuracy of altimetry-based sea level records at global and regional scales needs to be significantly improved. For example, the global mean and regional sea level trend uncertainty should become better than 0.3 and 0.5 mm year-1, respectively (currently 0.6 and 1-2 mm year-1). Similarly, interannual global mean sea level variations (currently uncertain to 2-3 mm) need to be monitored with better accuracy. In this paper, we present various data improvements achieved within the European Space Agency (ESA) Climate Change Initiative (ESA CCI) project on "Sea Level" during its first phase (2010-2013), using multi-mission satellite altimetry data over the 1993-2010 time span. In a first step, using a new processing system with dedicated algorithms and adapted data processing strategies, an improved set of sea level products has been produced. The main improvements include: reduction of orbit errors and wet/dry atmospheric correction errors, reduction of instrumental drifts and bias, intercalibration biases, intercalibration between missions and combination of the different sea level data sets, and an improvement of the reference mean sea surface. We also present preliminary independent validations of the SL_cci products, based on tide gauges comparison and a sea level budget closure approach, as well as comparisons with ocean reanalyses and climate model outputs.

  2. Coastal vulnerability assessment of Dry Tortugas National Park (DRTO) to sea-level rise

    USGS Publications Warehouse

    Pendleton, Elizabeth A.; Thieler, E. Robert; Williams, S. Jeffress

    2005-01-01

    A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within Dry Tortugas National Park in Florida. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, historical shoreline change rates, mean tidal range and mean significant wave height. The rankings for each input variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Dry Tortugas National Park (DRTO) consists of relatively stable to washover-dominated portions of carbonate beach and man-made fortification. The areas within Dry Tortugas that are likely to be most vulnerable to sea-level rise are those with the highest rates of shoreline erosion and the highest wave energy.

  3. Coastal Vulnerability Assessment of Padre Island National Seashore (PAIS) to Sea-Level Rise

    USGS Publications Warehouse

    Pendleton, Elizabeth A.; Thieler, E. Robert; Williams, S. Jeffress; Beavers, Rebecca S.

    2004-01-01

    A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within Padre Island National Seashore in Texas. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, shoreline change rates, mean tidal range and mean significant wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Padre Island National Seashore consists of stable to washover dominated portions of barrier beach backed by wetland, marsh, tidal flat, or grassland. The areas within Padre that are likely to be most vulnerable to sea-level rise are those with the highest occurrence of overwash and the highest rates of shoreline change.

  4. Coastal vulnerability assessment of Assateague Island National Seashore (ASIS) to sea-level rise

    USGS Publications Warehouse

    Pendleton, Elizabeth A.; Williams, S. Jeffress; Thieler, E. Robert

    2004-01-01

    A coastal vulnerability index (CVI, http://pubs.usgs.gov/of/2004/1020/html/cvi.htm) was used to map relative vulnerability of the coast to future sea-level rise within Assateague Island National Seashore (ASIS) in Maryland and Virginia. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, shoreline change rates, mean tidal range and mean wave height. Rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Assateague Island consists of stable and washover dominated portions of barrier beach backed by wetland and marsh. The areas within Assateague that are likely to be most vulnerable to sea-level rise are those with the highest occurrence of overwash and the highest rates of shoreline change.

  5. Coastal vulnerability assessment of Cape Cod National Seashore to sea-level rise

    USGS Publications Warehouse

    Hammar-Klose, Erika S.; Pendleton, Elizabeth A.; Thieler, E. Robert; Williams, S. Jeffress

    2003-01-01

    A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within the Cape Cod National Seashore (CACO). The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, shoreline change rates, mean tidal range and mean wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. CACO consists of high glacial cliffs, beaches, sand spits, and salt marsh wetlands. The areas most vulnerable to sea-level rise are those with the lowest regional coastal slopes, geomorphologic types that are susceptible to inundation, and the highest rates of shoreline change. Most of CACO's infrastructure lies on high elevation uplands away from the shore; most high use areas are accessible by foot only. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers.

  6. Coastal vulnerability assessment of Olympic National Park to sea-level rise

    USGS Publications Warehouse

    Pendleton, Elizabeth A.; Hammar-Klose, Erika S.; Thieler, E. Robert; Williams, S. Jeffress

    2004-01-01

    A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within Olympic National Park (OLYM), Washington. The CVI scores the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, shoreline change rates, mean tidal range and mean wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. The Olympic National Park coast consists of rocky headlands, pocket beaches, glacial-fluvial features, and sand and gravel beaches. The Olympic coastline that is most vulnerable to sea-level rise are beaches in gently sloping areas.

  7. Coastal vulnerability assessment of Fire Island National Seashore to sea-level rise

    USGS Publications Warehouse

    Pendleton, Elizabeth A.; Williams, S. Jeffress; Thieler, E. Robert

    2004-01-01

    A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within Fire Island National Seashore (FIIS), New York. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, shoreline change rates, mean tidal range and mean wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. Fire Island consists of stable and washover dominated portions of barrier beach backed by lagoons, tidal wetlands and marsh. The areas most vulnerable to sea-level rise are those with the highest historic occurrence of overwash and the highest rates of shoreline change. Implementation of large-scale beach nourishment and other coastal engineering alternatives being considered for Fire Island could alter the CVI computed here. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers.

  8. Coastal vulnerability assessment of Cape Hatteras National Seashore (CAHA) to sea-level rise

    USGS Publications Warehouse

    Pendleton, Elizabeth A.; Theiler, E. Robert; Williams, S. Jeffress

    2005-01-01

    A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within Cape Hatteras National Seashore (CAHA) in North Carolina. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, historical shoreline change rates, mean tidal range, and mean significant wave height. The rankings for each variable were combined and an index value was calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Cape Hatteras National Seashore consists of stable and washover dominated segments of barrier beach backed by wetland and marsh. The areas within Cape Hatteras that are likely to be most vulnerable to sea-level rise are those with the highest occurrence of overwash and the highest rates of shoreline change.

  9. Coastal vulnerability assessment of Point Reyes National Seashore (PORE) to sea-level rise

    USGS Publications Warehouse

    Pendleton, Elizabeth A.; Thieler, E. Robert; Williams, S. Jeffress

    2006-01-01

    A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within Point Reyes National Seashore in Northern California. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, historical shoreline change rates, mean tidal range and mean significant wave height. The rankings for each input variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Point Reyes National Seashore consists of sand and gravel beaches, rock cliffs, sand dune cliffs, and pocket beaches. The areas within Point Reyes that are likely to be most vulnerable to sea-level rise are areas of unconsolidated sediment where the coastal slope is lowest and wave energy is high.

  10. Late mid-Holocene sea-level oscillation: A possible cause

    NASA Astrophysics Data System (ADS)

    Scott, D. B.; Collins, E. S.

    Sea level oscillated between 5500 and 3500 years ago at Murrells Inlet, South Carolina, Chezzetcook and Baie Verte, Nova Scotia and Montmagny, Quebec. The oscillation is well constrained by foraminiferal marsh zonations in three locations and by diatoms in the fourth one. The implications are: (1) there was a eustatic sea-level oscillation of about 2-10 m in the late mid-Holocene on the southeast coast of North America (South Carolina to Quebec) that is not predicted by present geophysical models of relative sea-level change; (2) this oscillation coincides with oceanographic cooling on the east coast of Canada that we associate with melting ice; and (3) this sea- level oscillation/climatic event coincides exactly with the end of pyramid building in Egypt which is suggested to have resulted from a climate change (i.e. drought, cooling). This sea-level/climatic change is a prime example of feedback where climatic warming in the mid-Holocene promoted ice melt in the Arctic which subsequently caused climatic cooling by opening up Arctic channels releasing cold water into the Inner Labrador Current that continued to intensify until 4000 years ago. This sea-level event may also be the best way of measuring when the final ice melted since most estimates of the ages of the last melting are based on end moraine dates in the Arctic which may not coincide with when the last ice actually melted out, since there is no way of dating the final ice positions.

  11. Challenges in Projecting Sea Level Rise impacts on the Coastal Environment of South Florida (Invited)

    NASA Astrophysics Data System (ADS)

    Obeysekera, J.; Park, J.; Irizarry-Ortiz, M. M.; Barnes, J. A.; Trimble, P.; Said, W.

    2010-12-01

    Due to flat topography, a highly transmissive groundwater aquifer, and a growing population with the associated infrastructure, South Floridas coastal environment is one of the most vulnerable areas to sea level rise. Current projections of sea level rise and the associated storm surges will have direct impacts on coastal beaches and infrastructure, flood protection, freshwater aquifers, and both the isolated and regional wetlands. Uncertainties in current projections have made it difficult for regional and local governments to develop adaptation strategies as such measures will depend heavily on the temporal and spatial patterns of sea level rise in the coming decades. We demonstrate the vulnerability of both the built and natural environments of the coastal region and present the current efforts to understand and predict the sea level rise estimate that management agencies could employ in planning of adaptation strategies. In particular, the potential vulnerabilities of the flood control system as well as the threat to the water supply wellfields in the coastal belt will be presented. In an effort to understand the historical variability of sea level rise, we present linkages to natural phenomena such as Atlantic Multi-Decadal Oscillation, and the analytical methods we have developed to provide probabilistic projections of both mean sea level rise and the extremes.

  12. Coastal vulnerability assessment of Cumberland Island National Seashore (CUIS) to sea-level rise

    USGS Publications Warehouse

    Pendleton, Elizabeth A.; Thieler, E. Robert; Jeffress Williams, S.

    2004-01-01

    A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within Cumberland Island National Seashore in Georgia. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, historical shoreline change rates, mean tidal range and mean significant wave height. The rankings for each input variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. Cumberland Island National Seashore consists of stable to washover-dominated portions of barrier beach backed by wetland, marsh, mudflat and tidal creek. The areas within Cumberland that are likely to be most vulnerable to sea-level rise are those with the lowest foredune ridge and highest rates of shoreline erosion.

  13. Spectroscopic analysis of global tide gauge sea level data

    NASA Technical Reports Server (NTRS)

    Trupin, A.; Wahr, J.

    1990-01-01

    Yearly and monthly global tide-gage sea-level data are fitted to numerically generated tidal data in order to search for the 18.6-yr lunar nodal tide and 14-month pole tide. Both of these tides are clearly evident, with amplitudes and phases that are consistent with a global equilibrium response. The ocean's response to atmospheric pressure is studied with the least-squares fit technique. Consideration is given to the global rise in sea level, the effects of postglacial rebound, and the possible causes of the enhanced pole tides in the North Sea, the Baltic Sea, and the Gulf of Bothnia. The results support O'Connor's (1986) suggestion that the enhanced pole tide in these regions is due to meteorological forcing rather than a basin-scale resonance. Also, the global average of the tide-gage data show an increase in sea level over tha last 80 yr of between 1.1 and 1.9 mm/yr.

  14. Oyster reefs can outpace sea-level rise

    NASA Astrophysics Data System (ADS)

    Rodriguez, Antonio B.; Fodrie, F. Joel; Ridge, Justin T.; Lindquist, Niels L.; Theuerkauf, Ethan J.; Coleman, Sara E.; Grabowski, Jonathan H.; Brodeur, Michelle C.; Gittman, Rachel K.; Keller, Danielle A.; Kenworthy, Matthew D.

    2014-06-01

    In the high-salinity seaward portions of estuaries, oysters seek refuge from predation, competition and disease in intertidal areas, but this sanctuary will be lost if vertical reef accretion cannot keep pace with sea-level rise (SLR). Oyster-reef abundance has already declined ~85% globally over the past 100 years, mainly from over harvesting, making any additional losses due to SLR cause for concern. Before any assessment of reef response to accelerated SLR can be made, direct measures of reef growth are necessary. Here, we present direct measurements of intertidal oyster-reef growth from cores and terrestrial lidar-derived digital elevation models. On the basis of our measurements collected within a mid-Atlantic estuary over a 15-year period, we developed a globally testable empirical model of intertidal oyster-reef accretion. We show that previous estimates of vertical reef growth, based on radiocarbon dates and bathymetric maps, may be greater than one order of magnitude too slow. The intertidal reefs we studied should be able to keep up with any future accelerated rate of SLR (ref. ) and may even benefit from the additional subaqueous space allowing extended vertical accretion.

  15. A New Method for Reconstructing Sea-Level and Deep-Sea-Temperature Variability over the Past 5.3 Million Years

    NASA Astrophysics Data System (ADS)

    Rohling, E. J.

    2014-12-01

    Ice volume (and hence sea level) and deep-sea temperature are key measures of global climate change. Sea level has been documented using several independent methods over the past 0.5 million years (Myr). Older periods, however, lack such independent validation; all existing records are related to deep-sea oxygen isotope (d18O) data that are influenced by processes unrelated to sea level. For deep-sea temperature, only one continuous high-resolution (Mg/Ca-based) record exists, with related sea-level estimates, spanning the past 1.5 Myr. We have recently presented a novel sea-level reconstruction, with associated estimates of deep-sea temperature, which independently validates the previous 0-1.5 Myr reconstruction and extends it back to 5.3 Myr ago. A serious of caveats applies to this new method, especially in older times of its application, as is always the case with new methods. Independent validation exercises are needed to elucidate where consistency exists, and where solutions drift away from each other. A key observation from our new method is that a large temporal offset existed during the onset of Plio-Pleistocene ice ages, between a marked cooling step at 2.73 Myr ago and the first major glaciation at 2.15 Myr ago. This observation relies on relative changes within the dataset, which are more robust than absolute values. I will discuss our method and its main caveats and avenues for improvement.

  16. Cosmic Rays with Portable Geiger Counters: From Sea Level to Airplane Cruise Altitudes

    ERIC Educational Resources Information Center

    Blanco, Francesco; La Rocca, Paola; Riggi, Francesco

    2009-01-01

    Cosmic ray count rates with a set of portable Geiger counters were measured at different altitudes on the way to a mountain top and aboard an aircraft, between sea level and cruise altitude. Basic measurements may constitute an educational activity even with high school teams. For the understanding of the results obtained, simulations of extensive

  17. Cosmic Rays with Portable Geiger Counters: From Sea Level to Airplane Cruise Altitudes

    ERIC Educational Resources Information Center

    Blanco, Francesco; La Rocca, Paola; Riggi, Francesco

    2009-01-01

    Cosmic ray count rates with a set of portable Geiger counters were measured at different altitudes on the way to a mountain top and aboard an aircraft, between sea level and cruise altitude. Basic measurements may constitute an educational activity even with high school teams. For the understanding of the results obtained, simulations of extensive…

  18. Accelerated sea level rise and Florida Current transport

    NASA Astrophysics Data System (ADS)

    Park, J.; Sweet, W.

    2015-07-01

    The Florida Current is the headwater of the Gulf Stream and is a component of the North Atlantic western boundary current from which a geostrophic balance between sea surface height and mass transport directly influence coastal sea levels along the Florida Straits. A linear regression of daily Florida Current transport estimates does not find a significant change in transport over the last decade; however, a nonlinear trend extracted from empirical mode decomposition (EMD) suggests a 3 Sv decline in mean transport. This decline is consistent with observed tide gauge records in Florida Bay and the straits exhibiting an acceleration of mean sea level (MSL) rise over the decade. It is not known whether this recent change represents natural variability or the onset of the anticipated secular decline in Atlantic meridional overturning circulation (AMOC); nonetheless, such changes have direct impacts on the sensitive ecological systems of the Everglades as well as the climate of western Europe and eastern North America.

  19. Accelerated sea level rise and Florida Current transport

    NASA Astrophysics Data System (ADS)

    Park, J.; Sweet, W.

    2015-04-01

    The Florida Current is the headwater of the Gulf Stream and is a component of the North Atlantic western boundary current from which a geostrophic balance between sea surface height and mass transport directly influence coastal sea levels along the Florida Straits. A linear regression of daily Florida Current transport estimates does not find a significant change in transport over the last decade, however, a nonlinear trend extracted from empirical mode decomposition suggests a 3 Sv decline in mean transport. This decline is consistent with observed tide gauge records in Florida Bay and the Straits, all exhibiting an acceleration of mean sea level rise over the decade. It is not known whether this recent change represents natural variability or the onset of the anticipated secular decline in Atlantic meridional overturning circulation, nonetheless, such changes have direct impacts on the sensitive ecological systems of the Everglades as well as the climate of western Europe and eastern North America.

  20. Sea-level rise: towards understanding local vulnerability

    NASA Astrophysics Data System (ADS)

    Rahmstorf, Stefan

    2012-06-01

    Projections of global sea-level rise into the future have become more pessimistic over the past five years or so. A global rise by more than one metre by the year 2100 is now widely accepted as a serious possibility if greenhouse gas emissions continue unabated. That is witnessed by the scientific assessments that were made since the last IPCC report was published in 2007. The Delta Commission of the Dutch government projected up to 1.10 m as a 'high-end' scenario (Vellinga et al 2009). The Scientific Committee on Antarctic Research (SCAR) projected up to 1.40 m (Scientific Committee on Antarctic Research 2009), and the Arctic Monitoring and Assessment Programme (AMAP) gives a range of 0.90-1.60 m in its 2011 report (Arctic Monitoring and Assessment Programme 2011). And recently the US Army Corps of Engineers recommends using a 'low', an 'intermediate' and a 'high' scenario for global sea-level rise when planning civil works programmes, with the high one corresponding to a 1.50 m rise by 2100 (US Army Corps of Engineers 2011). This more pessimistic view is based on a number of observations, most importantly perhaps the fact that sea level has been rising at least 50% faster in the past decades than projected by the IPCC (Rahmstorf et al 2007, IPCC 2007). Also, the rate of rise (averaged over two decades) has accelerated threefold, from around 1 mm yr-1 at the start of the 20th century to around 3 mm yr-1 over the past 20 years (Church and White 2006), and this rate increase closely correlates with global warming (Rahmstorf et al 2011). The IPCC projections, which assume almost no further acceleration in the 20th century, thus look less plausible. And finally the observed net mass loss of the two big continental ice sheets (Van den Broeke et al 2011) calls into question the assumption that ice accumulation in Antarctica would largely balance ice loss from Greenland in the course of further global warming (IPCC 2007). With such a serious sea-level rise on the horizon, experts are increasingly looking at its potential impacts on coasts to facilitate local adaptation planning. This is a more complex issue than one might think, because different stretches of coast can be affected in very different ways. First of all, the sea-level response to global warming will not be globally uniform, since factors like changes in ocean currents (Levermann et al 2005) and the changing gravitational pull of continental ice (Mitrovica et al 2001) affect the local rise. Secondly, superimposed on the climatic trend is natural variability in sea level, which regionally can be as large as the climatic signal on multi-decadal timescales. Over the past decades, sea level has dropped in sizable parts of the world ocean, although it has of course risen in global mean (IPCC 2007). Thirdly, local land uplift or subsidence affects the local sea-level change relative to the coast, both for natural reasons (post-glacial isostatic adjustment centred on regions that were covered by ice sheets during the last ice age) and artificial ones (e.g., extraction of water or oil as in the Gulf of Mexico). Finally, local vulnerability to sea-level rise depends on many factors. Two interesting new studies in this journal (Tebaldi et al 2012, Strauss et al 2012) make important steps towards understanding sea-level vulnerability along the coasts of the United States, with methods that could also be applied elsewhere. The first, by Strauss and colleagues, merges high-resolution topographic data and a newly available tidal model together with population and housing data in order to estimate what land area and population would be at risk given certain increments in sea level. The results are mapped and tabulated at county and city level. They reveal the 'hot spots' along the US coast where sea-level rise is of the highest concern because of large populations living near the high-tide line: New York City and Long Island; the New Jersey shore; the Norfolk, Virginia, area; near Charleston, South Carolina; coastal cities across Florida, especially its southeast and the Tampa area; New Orleans; the San Francisco Bay Area and San Joaquin Delta; and greater Los Angeles. Overall, 3.7 million people across the US are estimated to live within 1 m of the present high-tide line. The second paper, by Tebaldi et al, specifically looks at storm surges and how their frequency is expected to change along the US coastline in the coming four decades due to rising sea levels. They first estimate future local sea-level rise relative to the land by combining the observed local trend of the past fifty years with a future acceleration due to global warming as estimated by a semi-empirical model (Vermeer and Rahmstorf 2009). Then they use past storm surge statistics for many different locations and shift the return level curves according to the projected sea-level rise. The authors find that by mid-century, in some locations what is now a once-per-century flooding event could become an annual event. Those are exceptional places—but at about a third of the sites investigated, a century flood could become a once-per-decade flood. Of course, many of these events need not have dramatic impacts: in fact, locations where rare floods are quite small in amplitude (and hence presumably modest in their impacts) are precisely those where the return period decreases most dramatically. In a place where the once-per-century flood is only 50 cm higher than the annual flood, a typical 30 cm rise in sea level makes a bigger difference than one in a place where the century flood is 2 m higher than the annual flood. Nevertheless, the expected large changes in return periods and return levels of storm surges clearly demonstrate that accounting for accelerating sea-level rise is vital in the planning and design of coastal infrastructure. But most importantly, these studies highlight the fact that the modern world, with many millions of people living right by the coast, is highly vulnerable to even modest sea-level rise. Losing just 1% of the present continental ice would raise sea level globally by about 75 cm—a tiny amount in the perspective of palaeoclimate history, e.g. the 120 m rise at the end of the last ice age, but a large amount in terms of impacts on human society. We should do everything we can to limit global warming and thereby sea-level rise to a manageable level. References Arctic Monitoring and Assessment Programme 2011 Snow, Water, Ice and Permafrost in the Arctic (Oslo: AMAP) Church J A and White N J 2006 A 20th century acceleration in global sea-level rise Geophys. Res. Lett. 33 L01602 IPCC 2007 Climate Change 2007: The Physical Science Basis. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change ed S Solomon et al (Cambridge: Cambridge University Press) Levermann A, Griesel A, Hofmann M, Montoya M and Rahmstorf S 2005 Dynamic sea level changes following changes in the thermohaline circulation Clim. Dyn. 24 347-54 Mitrovica J X, Tamisiea M E, Davis J L and Milne G A 2001 Recent mass balance of polar ice sheets inferred from patterns of global sea-level change Nature 409 1026-9 Rahmstorf S, Cazenave A, Church J A, Hansen J E, Keeling R F, Parker D E and Somerville C J 2007 Recent climate observations compared to projections Science 316 709 Rahmstorf S, Perrette M and Vermeer M 2011 Testing the robustness of semi-empirical sea level projections Clim. Dyn. at press (doi:10.1007/s00382-011-1226-7) Scientific Committee on Antarctic Research 2009 Antarctic Climate Change and the Environment (Cambridge: Scott Polar Research Institute) Strauss B, Ziemlinski R, Weiss J and Overpeck J T 2012 Tidally-adjusted estimates of topographic vulnerability to sea level rise and flooding for the contiguous United States Environ. Res. Lett. 7 014033 Tebaldi C, Strauss B and Zervas C 2012 Modelling sea level rise impacts on storm surges along US coasts Environ. Res. Lett. 7 014032 US Army Corps of Engineers 2011 Sea-Level Change Considerations for Civil Works Programs (Washington, DC: Department of the Army) Van den Broeke M R, Bamber J, Lenaerts J and Rignot E 2011 Ice sheets and sea level: thinking outside the box Sur. Geophys. 32 495-505 Vellinga P, Katsman C A, Sterl A and Beersma J J 2009 Exploring high-end climate change scenarios for flood protection of the Netherlands International Scientific Assessment Carried out at the Request of the Delta Committee (De Bilt: KNMI) Vermeer M and Rahmstorf S 2009 Global sea level linked to global temperature Proc. Natl Acad. Sci. USA 106 21527-32

  1. Caspian Sea Level and Cosmo-Geophysical Processes: Satellite and Terrestrial Data Analysis

    NASA Astrophysics Data System (ADS)

    Kaftan, Vladimir; Lebedev, Sergey; Komitov, Boris

    The Caspian Sea basin appears to be a giant water collection of the largest European rivers and underground stream flows. That is exactly why Caspian Sea level changes are revealed as an indicator of regional climate changes. Instrumental tide gauge observations continue about two centuries at the Caspian Sea shore. At the last centuries the changes of the Sea level were going on unpredictably - from the fast shallow (- 5 cm/y.) to the catastrophic rise (12 cm/y.). The end of the last century was finished by unexpected sharp change of the fast rise to the equally fast lowering with the velocity of 1.5 cm/y. Caspian Sea researches about regularities of its level were carried out continuously by using of terrestrial observation techniques. The closed relationships between level changes, solar activity and Earth’s rotation variation were estimated over the period of the last centuries. The last decades are characterized by the intensive development of satellite and space observation techniques. Nowadays the accuracy and spatial-temporal resolution of sea level and cosmo-geophysical processes observation is considerably increased. Now the more informative means of the Caspian Sea level study are satellite altimetry of TOPEX/Poseidon, Jason-1 and Jason-2 missions. At the last decades the Earth’s rotation parameters are determining permanently using such recent measurement techniques as GNSS and VLBI. The last of them provides the 10.7 cm solar flux observation. Therefore the large current data amount ensuring the study of cause-and-effect relations between the Caspian Sea level and geophysical processes of global and space scales is collected today. The results of the resent precise observation data analysis with high resolution as well as the long Caspian Sea level time-series combining terrestrial and space observation are proposed to the research community. Spectral characteristics of the Caspian Sea level changes, Earth’s rotation parameters (LOD), solar activity and other processes are studying. High amplitude oscillation components having close periods are revealed in the spectra of all analyzed processes. Caspian Sea level oscillations are following in an antiphase the solar activity changes. The results of the analysis provide the new and important information facilitating to reveal the causes of the regional climate changes.

  2. Increased sea level promotes coral cover on shallow reef flats in the Andaman Sea, eastern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Brown, B. E.; Dunne, R. P.; Phongsuwan, N.; Somerfield, P. J.

    2011-12-01

    Sea level in the Indian Ocean is subject to considerable temporal and spatial variabilities. During the period 1960-2009 at Phuket, Thailand, in the NE Indian Ocean, mean sea level increased by 2.7 mm y-1. Regular monitoring of coral cover on fringing reef flats at Phuket since 1979 revealed a sensitive response of this habitat to both transient sea-level depressions and sea-level elevation. Since 1987 when more frequent sampling began, coral cover was positively correlated with the mean sea level experienced over the preceding months. Changing mean sea level explained a high proportion of the observed variation in cover, with overall increasing sea levels and a lack of negative sea-level anomalies promoting cover on the outer reef flats. Concomitantly, there have been no changes in reef community structure or any apparent shifts in zonation patterns across the reef. While future benefits of continued increases in mean sea level on reef flats in the region will be constrained by the frequency and intensity of sea-level depressions associated with the Indian Ocean Dipole, and bleaching events, the overall picture for these shallow reefs is a positive one as they respond to increasing sea level and show rapid recovery from environmental disturbances.

  3. The Offlap Break Position Vs Sea Level: A Discussion

    NASA Astrophysics Data System (ADS)

    Tropeano, M.; Pieri, P.; Pomar, L.; Sabato, L.

    Sedimentary lithosomes with subhorizontal topsets, basinward prograding foresets and subhorizontal bottomsets are common in the geologic record, and most of them display similar bedding architectures and/or seismic reflection patterns (i.e. Gylbert- type deltas and shelf wedges). Nevertheless, in shallow marine settings these bodies may form in distinct sedimentary environments and they result from different sed- imentary processes. The offlap break (topset edge) occurs in relation to the posi- tion of baselevel and two main groups of lithosomes can be differentiated with re- spect to the position of the offlap break within the shelf profile. The baselevel of the first group is the sea level (or lake level); the topsets are mainly composed by continental- or very-shallow-water sedimentary facies and the offlap break practi- cally corresponds to the shoreline. Exemples of these lithosomes are high-constructive deltas (river-dominated deltas) and prograding beaches. For the second group, base- level corresponds to the base of wave/tide traction, and their topsets are mostly composed by shoreface/nearshore deposits. Examples of these lithosomes are high- destructive deltas (wave/tide-dominated deltas) and infralittoral prograding wedges (i.e Hernandez-Molina et al., 2000). The offlap break corresponds to the shelf edge (shoreface edge), which is located at the transition between nearshore and offshore set- tings, where a terrace prodelta- or transition-slope may develop (Pomar &Tropeano, 2001). Two main problems derive from these alternative interpretations of shallow- marine seaward prograding lithosomes: 1) both in ancient sedimentary shallow-marine successios (showing seaward prograding foresets) and in high resolution seismic pro- files (showing shelf wedges), the offlap break is commonly considered to correspond to the sea-level (shoreline) and used to inferr paleo sea-level positions and to construct sea-level curves. Without a good facies control, this use of the offlap break might cause a misinterpretation of the ancient sea-level positions and the inferred relative sea-level changes. 2) both baselevels, the sea level and the wave/tide base, govern sedimentary accumulation in wave/tide dominated shelves and, consequently, two offlap breaks may coexist (beach edge and shoreface edge) in shallow-marine depositional profiles (Carter et al., 1991). In this setting, two seaward-clinobedded lithosomes, separated by an unconformity, may develop during relative still-stand or falls of the sea-level (Hill et al., 1998). In this case, the two stacked lithosomes could be misinterpreted as two different systems tracts, or sequences, and it could led to the construction of an 1 uncorrect curve of sea-level changes. Carter R.M., Abbott S.T., Fulthorpe C.S., Haywick D.W. and Henderson R.A. (1991): Application of global sea-level and sequence-stratigraphic models in Southern Hemi- sphere Neogene strata from New Zealand. Sp. Publ. IAS, 12, 41-65. Hernández- Molina F.J., Fernández-Salas L.M., Lobo F., Somoza L., Diaz-del-Rio V. and Alver- inho Dias J.M. (2000): The infralittoral prograding wedge: a new large-scale prograda- tional sedimentary body in shallow marine environments. Geo-Marine Letters, 20, 109-117. Hill P.R., Longuépée H. and Roberge M. (1998). Live from Canada: forced regression in action; deltaic shoreface sandbodies being formed. Abstracts, 15th Int. Cong. IAS, Alicante (Spain), 427-428. Pomar L. and Tropeano M. (2001). The Cal- carenite di Gravina Formation in Matera (southern Italy): new insights for coarse- grained, large-scale, cross-bedded bodies encased in offshore deposits. AAPG Bull., 85, 661-689. 2

  4. Long-Memory and the Sea Level-Temperature Relationship: A Fractional Cointegration Approach

    PubMed Central

    Ventosa-Santaulria, Daniel; Heres, David R.; Martnez-Hernndez, L. Catalina

    2014-01-01

    Through thermal expansion of oceans and melting of land-based ice, global warming is very likely contributing to the sea level rise observed during the 20th century. The amount by which further increases in global average temperature could affect sea level is only known with large uncertainties due to the limited capacity of physics-based models to predict sea levels from global surface temperatures. Semi-empirical approaches have been implemented to estimate the statistical relationship between these two variables providing an alternative measure on which to base potentially disrupting impacts on coastal communities and ecosystems. However, only a few of these semi-empirical applications had addressed the spurious inference that is likely to be drawn when one nonstationary process is regressed on another. Furthermore, it has been shown that spurious effects are not eliminated by stationary processes when these possess strong long memory. Our results indicate that both global temperature and sea level indeed present the characteristics of long memory processes. Nevertheless, we find that these variables are fractionally cointegrated when sea-ice extent is incorporated as an instrumental variable for temperature which in our estimations has a statistically significant positive impact on global sea level. PMID:25426638

  5. Long-memory and the sea level-temperature relationship: a fractional cointegration approach.

    PubMed

    Ventosa-Santaulària, Daniel; Heres, David R; Martínez-Hernández, L Catalina

    2014-01-01

    Through thermal expansion of oceans and melting of land-based ice, global warming is very likely contributing to the sea level rise observed during the 20th century. The amount by which further increases in global average temperature could affect sea level is only known with large uncertainties due to the limited capacity of physics-based models to predict sea levels from global surface temperatures. Semi-empirical approaches have been implemented to estimate the statistical relationship between these two variables providing an alternative measure on which to base potentially disrupting impacts on coastal communities and ecosystems. However, only a few of these semi-empirical applications had addressed the spurious inference that is likely to be drawn when one nonstationary process is regressed on another. Furthermore, it has been shown that spurious effects are not eliminated by stationary processes when these possess strong long memory. Our results indicate that both global temperature and sea level indeed present the characteristics of long memory processes. Nevertheless, we find that these variables are fractionally cointegrated when sea-ice extent is incorporated as an instrumental variable for temperature which in our estimations has a statistically significant positive impact on global sea level. PMID:25426638

  6. Tidal level response to sea-level rise in the yangtze estuary

    NASA Astrophysics Data System (ADS)

    Gong, Zheng; Zhang, Chang-kuan; Wan, Li-ming; Zuo, Jun-cheng

    2012-03-01

    The rise of tidal level in tidal reaches induced by sea-level rise has a large impact on flood control and water supply for the regions around the estuary. This paper focuses on the variations of tidal level response along the tidal reaches in the Yangtze Estuary, as well as the impacts of upstream discharge on tidal level response, due to the sea-level rise of the East China Sea. Based on the Topex/Poseidon altimeter data obtained during the period 1993˜2005, a stochastic dynamic analysis was performed and a forecast model was run to predict the sea-level rise of the East China Sea. Two-dimensional hydrodynamic numerical models downscaling from the East China Sea to estuarine areas were implemented to analyze the rise of tidal level along the tidal reaches. In response to the sea-level rise, the tidal wave characteristics change slightly in nearshore areas outside the estuaries, involving the tidal range and the duration of flood and ebb tide. The results show that the rise of tidal level in the tidal reaches due to the sea-level rise has upstream decreasing trends. The step between the stations of Zhangjiagang and Shiyiwei divides the tidal reaches into two parts, in which the tidal level response declines slightly. The rise of tidal level is 1˜2.5 mm/a in the upper part, and 4˜6 mm/a in the lower part. The stations of Jiangyin and Yanglin, as an example of the upper part and the lower part respectively, are extracted to analyze the impacts of upstream discharge on tidal level response to the sea-level rise. The relation between the rise of tidal level and the upstream discharge can be fitted well with a quadratic function in the upper part. However, the relation is too complicated to be fitted in the lower part because of the tide dominance. For comparison purposes, hourly tidal level observations at the stations of Xuliujing and Yanglin during the period 1993˜2009 are adopted. In order to uniform the influence of upstream discharge on tidal level for a certain day each year, the hourly tidal level observations are corrected by the correlation between the increment of tidal level and the increment of daily mean upstream discharge. The rise of annual mean tidal level is evaluated. The resulting rise of tidal level at the stations of Xuliujing and Yanglin is 3.0 mm/a and 6.6 mm/a respectively, close to the rise of 5 mm/a according to the proposed relation between the rise of tidal level and the upstream discharge.

  7. Mid-Cretaceous Eustatic sea level fall: magnitude and timing in Gulf of Mexico

    SciTech Connect

    Vierbuchen, R.C.; Oestmann, M.A.; Greenlee, S.M.

    1987-05-01

    The magnitude and timing of a mid-Cretaceous sea level fall have been documented on the margins of the Gulf of Mexico in east Texas. Analysis of seismic, log, and paleontologic data from east Texas demonstrates that a fall of 60 to 100 m occurred at the end of Washita (mid-Cenomanian) time. This sea level fall has been identified elsewhere on the shelves of the Gulf of Mexico and is proposed to have caused the mid-Cretaceous unconformity of the deep sea and the termination of Washita carbonate deposition. They conclude that this sea level fall is of regional significance and eustatic origin. The magnitude and timing of the fall agree with those postulated by Vail and others, and Haq and others, who recognized a major sea level fall in mid-Cenomanian time. The magnitude of sea level fall is estimated from the difference in elevation between carbonate buildups on the Buda margin, which accumulated at or near sea level, and fluvial deposits in the lower Woodbine, which immediately overlie Buda carbonates and have been drilled up to 20 km basinward of the shelf margin. After constructing a datum along the preexisting Buda shelf, they measure the thickness of sediment from this datum to the onlapping fluvial, lower Woodbine siliciclastics. This measurement is then corrected for compaction, isostatic subsidence due to sediment loading, and thermotectonic subsidence. The result, 60 m, is considered a minimum estimate. A similar measurement to the lowest seismically identified coastal onlap in the lower Woodbine yields an estimate of 100 m.

  8. Anomalous secular sea-level acceleration in the Baltic Sea caused by glacial isostatic adjustment

    NASA Astrophysics Data System (ADS)

    Spada, Giorgio; Galassi, Gaia; Olivieri, Marco

    2014-05-01

    Observations from the global array of tide gauges show that global sea-level has been rising at an average rate of 1.5-2 mm/yr during the last ˜ 150 years (Spada & Galassi, 2012). Although a global sea-level acceleration was initially ruled out, subsequent studies have coherently proposed values of ˜1 mm/year/century (Olivieri & Spada, 2012). More complex non-linear trends and abrupt sea-level variations have now also been recognized. Globally, they could manifest a regime shift between the late Holocene and the current rhythms of sea-level rise, while locally they result from ocean circulation anomalies, steric effects and wind stress (Bromirski et al. 2011). Although isostatic readjustment affects the local rates of secular sea-level change, a possible impact on regional acceleration have been so far discounted (Woodworth et al., 2009) since the process evolves on a millennium scale. Here we report a previously unnoticed anomaly in the long-term sea-level acceleration of the Baltic Sea tide gauge records, and we explain it by the classical post-glacial rebound theory and numerical modeling of glacial isostasy. Contrary to previous assumptions, our findings demonstrate that isostatic compensation plays a role in the regional secular sea-level acceleration. In response to glacial isostatic adjustment (GIA), tide gauge records located along the coasts of the Baltic Sea exhibit a small - but significant - long-term sea-level acceleration in excess to those in the far field of previously glaciated regions. The sign and the amplitude of the anomaly is consistent with the post-glacial rebound theory and with realistic numerical predictions of GIA models routinely employed to decontaminate the tide gauges observations from the GIA effects (Peltier, 2004). Model computations predict the existence of anomalies of similar amplitude in other regions of the globe where GIA is still particularly vigorous at present, but no long-term instrumental observations are available to support their existence. We confirm that a GIA correction for secular sea-level acceleration is not required in GSLA assessments because its average value is vanishingly small at the locations of the PSMSL tide gauges (Douglas, 1992). Nevertheless, GIA is contributing significantly on a regional scale, and therefore it should be recognized as one of the processes responsible for local, long-term sea-level acceleration. Reference: Bromirski, P.D., Miller, A.J., Flick, R.E. & Auad, G., 2011, J. Geoph. Res. 116, C07005; Douglas, B.C., 1992, J. Geoph. Res. 97, 12,699-12,706; Olivieri, M. & Spada, G., 2013, Global Planet. Change 109, 64-72; Peltier, W.R., 2004, Annu. Rev. Earth. Pl. Sc. 32, 111-149; Spada, G. & Galassi, G., 2012, Geophys. J. Int. 191, 1067-1094; Woodworth, P.L., White, N. J., Jevrejeva, S., Holgate, S. J., Church, J. A. & Gehrels, W. R., 2009, Int. J. Climatol. 29, 777-789.

  9. Global mean sea level variations from TOPEX/POSEIDON altimeter data

    SciTech Connect

    Nerem, R.S.

    1995-05-05

    The TOPEX/POSEIDON satellite altimeter mission has measured global mean sea level every 10 days over the last 2 years with a precision of 4 millimeters, which approaches the requirements for climate change research. The estimated rate of sea level change is +3.9 {+-} 0.8 millimeters per year. A substantial portion of this trend may represent a short-term variation unrelated to the long-term signal expected from global warming. For this reason, and because the long-term measurement accuracy requires additional monitoring, a longer time series is necessary before climate change signals can be unequivocally detected. 37 refs., 1 fig.

  10. Global Mean Sea Level Variations from TOPEX/POSEIDON Altimeter Data.

    PubMed

    Nerem, R S

    1995-05-01

    The TOPEX/POSEIDON satellite altimeter mission has measured global mean sea level every 10 days over the last 2 years with a precision of 4 millimeters, which approaches the requirements for climate change research. The estimated rate of sea level change is +3.9 +/- 0.8 millimeters per year. A substantial portion of this trend may represent a short-term variation unrelated to the long-term signal expected from global warming. For this reason, and because the long-term measurement accuracy requires additional monitoring, a longer time series is necessary before climate change signals can be unequivocally detected. PMID:17832385

  11. Low-frequency variability of sea level as related to the heat balance of global oceans

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Niiler, P.; Patzert, W.

    1991-01-01

    The TOPEX/POSEIDON mission will determine global changes of sea level with unprecedented accuracy. Our main objective is the use TOPEX/POSEIDON data, concurrent in situ ocean measurements, and other satellite observations to document and diagnose physical processes by which heat is exchanged with the atmosphere, stored in the ocean, or transported by ocean circulation. During the prelaunch period, our objectives are to advise the project on an improved method of retrieving sea level data and prepare for the application of TOPEX/POSEIDON data by developing a diagnostic model using in situ measurements and altimeter observations from Geosat and the European Remote Sensing satellite.

  12. Modeling Sea-Level Rise in San Francisco Bay Estuary

    San Francisco Bay — which has already lost the majority of its marsh habitat since the 19th Century — could lose even more marshes by the year 2100 due to sea level rise, according to a new USGS report. Animations, graphs and data from the USGS Open File Report 2013-1081 and th...

  13. Preparing Coastal Parks for Future Sea Level Rise

    NASA Astrophysics Data System (ADS)

    Young, R.; Peek, K.

    2012-04-01

    The United States National Park Service (NPS) manages significant stretches of shoreline along the U.S. Atlantic, Pacific, and Gulf Coasts that are vulnerable to long-term sea level rise, shoreline erosion, and storm impacts. These parks have a wide variety of missions— protecting some of the nation's most important natural and cultural resources. The parks must also provide visitor access and education requiring infrastructure such as roads, visitor centers, trails, and buildings for facilities management. Planning for the likely impacts from sea level rise to both resources and infrastructure is a complex balancing act. Using coastal engineering to protect cultural resources or infrastructure may harm natural resources. At the same time, there are clearly some cultural and historical resources that are so critical that they must be protected. In an attempt to begin to attack this dilemma, the NPS Climate Change Response Program has initiated a sea level rise adaptation study that will provide a first-order tally of the park assets at risk to sea level rise and to begin to develop a plan for prioritizing those assets that must be protected, those that can be moved or abandoned, and an examination of how best to approach this without harming critical natural resources. This presentation will discuss the preliminary results of this effort along with several relevant case studies.

  14. Fluctuating Mesozoic and Cenozoic sea levels and implications for stratigraphy

    SciTech Connect

    Haq, B.U. )

    1988-12-01

    Sequence stratigraphy encompasses depositional models of genetically related packages of sediments deposited during various phases of cycle of sea level change, i.e., from a lowstand to highstand to the subsequent lowstand. The application of these models to marine outcrops around the world and to subsurface data led to the construction of Mesozoic-Cenozoic sea level curves with greater event resolution than the earlier curves based on seismic data alone. Construction of these better resolution curves begins with an outline of the principles of sequence-stratigraphic analysis and the reconstruction of the history of sea level change from outcrop and subsurface data for the past 250 Ma. Examples of marine sections from North America, Europe, and Asia can be used to illustrate sequence analysis of outcrop data and the integration of chronostratigraphy with sea level history. Also important are the implications of sequence-stratigraphic methodology and the new cycle charts to various disciplines of stratigraphy, environmental reconstruction, and basin analysis. The relationship of unconformities along the continental margins to hiatuses and dissolution surfaces in the deep basins must also be explored, as well as the relevance of sequence-stratigraphic methodology to biofacies and source rock prediction.

  15. Interferometric System for Measuring Thickness of Sea Ice

    NASA Technical Reports Server (NTRS)

    Hussein, Ziad; Jordan, Rolando; McDonald, Kyle; Holt, Benjamin; Huang, John; Kugo, Yasuo; Ishimaru, Akira; Jaruwatanadilok, Semsak; Akins, Torry; Gogineni, Prasad

    2006-01-01

    The cryospheric advanced sensor (CAS) is a developmental airborne (and, potentially, spaceborne) radar-based instrumentation system for measuring and mapping the thickness of sea ice. A planned future version of the system would also provide data on the thickness of snow covering sea ice. Frequent measurements of the thickness of polar ocean sea ice and its snow cover on a synoptic scale are critical to understanding global climate change and ocean circulation.

  16. Milankovitch tuning of deep-sea records: Implications for maximum rates of change of sea level

    NASA Astrophysics Data System (ADS)

    Berger, Wolfgang H.

    2013-02-01

    The analysis of several stacked and tuned records from the deep-sea floor yields two rather different sets of values for rates of sea-level rise. One of these reflects "regular" growth and decay and the other represents rapid decay of polar ice. Typical rise rates during rapid decay are near 1.2 m per century; with higher values seemingly following an abundance distribution that may be described by a standard deviation of 0.4 m per century (one third of the typical value). Distributions are based on a millennium resolution, leaving room for higher values for selected centuries within any millennium. Nevertheless, rise values beyond 5 m per century seem highly unusual. The quality of the match between deep-sea record (taken as differential) and Milankovitch forcing is excellent for the last 400,000 years (that is, the time since the "mid-Brunhes Event," a period that may be referred to as the "Emiliani Chron") but is poor in certain time spans before that. Difficulties associated with precise dating and a changing level of instability of polar ice prevent identification of trigger events for deglaciation. What is observable is that during periods of rapid decay, once sea level started to rise, it kept doing so for millennia (presumably till suitable ice masses were used up). Thus, it seems that a rise of sea level is itself a positive feedback on rapid melting of ice. Negative feedback, if real (as assumed in certain hypotheses about the origin of the Younger Dryas) is an unexpected exception that presumably relies on a high threshold value of sea-level rise.

  17. Simulations of Sea Level Rise Effects on Complex Coastal Systems

    NASA Astrophysics Data System (ADS)

    Niedoroda, A. W.; Ye, M.; Saha, B.; Donoghue, J. F.; Reed, C. W.

    2009-12-01

    It is now established that complex coastal systems with elements such as beaches, inlets, bays, and rivers adjust their morphologies according to time-varying balances in between the processes that control the exchange of sediment. Accelerated sea level rise introduces a major perturbation into the sediment-sharing systems. A modeling framework based on a new SL-PR model which is an advanced version of the aggregate-scale CST Model and the event-scale CMS-2D and CMS-Wave combination have been used to simulate the recent evolution of a portion of the Florida panhandle coast. This combination of models provides a method to evaluate coefficients in the aggregate-scale model that were previously treated as fitted parameters. That is, by carrying out simulations of a complex coastal system with runs of the event-scale model representing more than a year it is now possible to directly relate the coefficients in the large-scale SL-PR model to measureable physical parameters in the current and wave fields. This cross-scale modeling procedure has been used to simulate the shoreline evolution at the Santa Rosa Island, a long barrier which houses significant military infrastructure at the north Gulf Coast. The model has been used to simulate 137 years of measured shoreline change and to extend these to predictions of future rates of shoreline migration.

  18. Keep up or drown: adjustment of western Pacific coral reefs to sea-level rise in the 21st century.

    PubMed

    van Woesik, R; Golbuu, Y; Roff, G

    2015-07-01

    Since the Mid-Holocene, some 5000 years ago, coral reefs in the Pacific Ocean have been vertically constrained by sea level. Contemporary sea-level rise is releasing these constraints, providing accommodation space for vertical reef expansion. Here, we show that Porites microatolls, from reef-flat environments in Palau (western Pacific Ocean), are 'keeping up' with contemporary sea-level rise. Measurements of 570 reef-flat Porites microatolls at 10 locations around Palau revealed recent vertical skeletal extension (78±13 mm) over the last 6-8 years, which is consistent with the timing of the recent increase in sea level. We modelled whether microatoll growth rates will potentially 'keep up' with predicted sea-level rise in the near future, based upon average growth, and assuming a decline in growth for every 1°C increase in temperature. We then compared these estimated extension rates with rates of sea-level rise under four Representative Concentration Pathways (RCPs). Our model suggests that under low-mid RCP scenarios, reef-coral growth will keep up with sea-level rise, but if greenhouse gas concentrations exceed 670 ppm atmospheric CO2 levels and with +2.2°C sea-surface temperature by 2100 (RCP 6.0 W m(-2)), our predictions indicate that Porites microatolls will be unable to keep up with projected rates of sea-level rise in the twenty-first century. PMID:26587277

  19. Cryogenic liquid level measuring probe

    NASA Technical Reports Server (NTRS)

    Dinkel, J. A.; Wegner, C. R.

    1968-01-01

    Universal probe, which contains a unique frequency discriminator, measures the static and dynamic levels of cryogenic liquids in a hydrogen bubble chamber. The probe allows boiling conditions or other turbulence to be observed throughout all the transition stages.

  20. Streamflow and Water Level Measurements

    USGS scientists Joel Galloway and Dan Thomas prepare to take streamflow and water level measurements of the flooded Red River in downtown Fargo, ND. The USGS Red River of the North at Fargo streamgage can be seen in the background....

  1. Sea surface temperature measurements with AIRS

    NASA Technical Reports Server (NTRS)

    Aumann, H.

    2003-01-01

    The comparison of global sea surface skin temperature derived from cloud-free AIRS super window channel at 2616 cm-1 (sst2616) with the Real-Time Global Sea Surface Temperature for September 2002 shows surprisingly small standard deviation of 0.44K.

  2. Low-frequency oscillations of the level of enclosed sea

    NASA Astrophysics Data System (ADS)

    Korotaev, G. K.

    2015-07-01

    This work studies the variable surface level of a small enclosed basin that is related to the problem of interpreting satellite altimetric data, which assist in observations only of a deviation of a marine basin from unknown average condition needed to be calculated for the reconstruction of the sea-level topography. The reconstruction of unknown average condition becomes especially uncertain for the enclosed basins with significant level oscillations due to a variable water balance and requires the attraction of a priori physical concepts. This work reveals the general principles of response of the sea level to the low-frequency changes of the water exchange through the boundary of the basin with a rather arbitrary morphology.

  3. Probabilistic reanalysis of twentieth-century sea-level rise

    NASA Astrophysics Data System (ADS)

    Hay, Carling C.; Morrow, Eric; Kopp, Robert E.; Mitrovica, Jerry X.

    2015-01-01

    Estimating and accounting for twentieth-century global mean sea-level (GMSL) rise is critical to characterizing current and future human-induced sea-level change. Several previous analyses of tide gauge records--employing different methods to accommodate the spatial sparsity and temporal incompleteness of the data and to constrain the geometry of long-term sea-level change--have concluded that GMSL rose over the twentieth century at a mean rate of 1.6 to 1.9 millimetres per year. Efforts to account for this rate by summing estimates of individual contributions from glacier and ice-sheet mass loss, ocean thermal expansion, and changes in land water storage fall significantly short in the period before 1990. The failure to close the budget of GMSL during this period has led to suggestions that several contributions may have been systematically underestimated. However, the extent to which the limitations of tide gauge analyses have affected estimates of the GMSL rate of change is unclear. Here we revisit estimates of twentieth-century GMSL rise using probabilistic techniques and find a rate of GMSL rise from 1901 to 1990 of 1.2 +/- 0.2 millimetres per year (90% confidence interval). Based on individual contributions tabulated in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, this estimate closes the twentieth-century sea-level budget. Our analysis, which combines tide gauge records with physics-based and model-derived geometries of the various contributing signals, also indicates that GMSL rose at a rate of 3.0 +/- 0.7 millimetres per year between 1993 and 2010, consistent with prior estimates from tide gauge records. The increase in rate relative to the 1901-90 trend is accordingly larger than previously thought; this revision may affect some projections of future sea-level rise.

  4. Evidence from the Seychelles of Last Interglacial Sea Level Oscillations

    NASA Astrophysics Data System (ADS)

    Vyverberg, K.; Dutton, A.; Dechnik, B.; Webster, J.; Zwartz, D.

    2014-12-01

    Several studies indicate that sea level oscillated during Marine Isotope Stage (MIS) 5e, but the details of these scenarios, including the number of sea level oscillations, are still debated. We lack a detailed understanding of the sensitivity of the large polar ice sheets to changes in temperature that could result in eustatic sea level oscillations. Because the Seychelles are located far from the margins of the Last Glacial Maximum northern hemisphere ice sheets, they have not been subjected to glacial isostatic adjustment, and have been tectonically stable since the Last Interglacial period; therefore, they provide a robust record of eustatic sea level during MIS 5e. All of the outcrops we examined contain unconformities and/or sharp transitions between facies, though the nature of these boundaries varies between sites. In some outcrops we observed a hardground comprising fine-grained, mollusc-rich sediment layer between distinct generations of in situ coralgal framework. In one outcrop, this succession was observed twice, where two generations of reef growth were each capped by a strongly indurated fine-grained, mollusc-rich sediment layer. At the site with the greatest vertical extent of outcrop, there is a marked difference in the taxonomic composition of the coral community above and below an unconformable surface, but the indurated fine-grained, sediment layer observed elsewhere was absent. Most of the other outcrops we studied contained a common succession of facies from in situ reef units overlain by cemented coral rubble. In two dated outcrops, the age of corals above and below the rubble layer are the same age. The hardgrounds and rubble layers may represent ephemeral exposure of the reef units during two drops in sea level. The inference of multiple meter-scale oscillations during the MIS 5e highstand indicates a more dynamic cryosphere than the present interglacial, although the climatic threshold for more volatile polar ice sheets is not yet clear.

  5. Probabilistic reanalysis of twentieth-century sea-level rise.

    PubMed

    Hay, Carling C; Morrow, Eric; Kopp, Robert E; Mitrovica, Jerry X

    2015-01-22

    Estimating and accounting for twentieth-century global mean sea level (GMSL) rise is critical to characterizing current and future human-induced sea-level change. Several previous analyses of tide gauge records--employing different methods to accommodate the spatial sparsity and temporal incompleteness of the data and to constrain the geometry of long-term sea-level change--have concluded that GMSL rose over the twentieth century at a mean rate of 1.6 to 1.9 millimetres per year. Efforts to account for this rate by summing estimates of individual contributions from glacier and ice-sheet mass loss, ocean thermal expansion, and changes in land water storage fall significantly short in the period before 1990. The failure to close the budget of GMSL during this period has led to suggestions that several contributions may have been systematically underestimated. However, the extent to which the limitations of tide gauge analyses have affected estimates of the GMSL rate of change is unclear. Here we revisit estimates of twentieth-century GMSL rise using probabilistic techniques and find a rate of GMSL rise from 1901 to 1990 of 1.2 ± 0.2 millimetres per year (90% confidence interval). Based on individual contributions tabulated in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, this estimate closes the twentieth-century sea-level budget. Our analysis, which combines tide gauge records with physics-based and model-derived geometries of the various contributing signals, also indicates that GMSL rose at a rate of 3.0 ± 0.7 millimetres per year between 1993 and 2010, consistent with prior estimates from tide gauge records.The increase in rate relative to the 1901-90 trend is accordingly larger than previously thought; this revision may affect some projections of future sea-level rise. PMID:25629092

  6. Bipolar seesaw control on last interglacial sea level.

    PubMed

    Marino, G; Rohling, E J; Rodríguez-Sanz, L; Grant, K M; Heslop, D; Roberts, A P; Stanford, J D; Yu, J

    2015-06-11

    Our current understanding of ocean-atmosphere-cryosphere interactions at ice-age terminations relies largely on assessments of the most recent (last) glacial-interglacial transition, Termination I (T-I). But the extent to which T-I is representative of previous terminations remains unclear. Testing the consistency of termination processes requires comparison of time series of critical climate parameters with detailed absolute and relative age control. However, such age control has been lacking for even the penultimate glacial termination (T-II), which culminated in a sea-level highstand during the last interglacial period that was several metres above present. Here we show that Heinrich Stadial 11 (HS11), a prominent North Atlantic cold episode, occurred between 135 ± 1 and 130 ± 2 thousand years ago and was linked with rapid sea-level rise during T-II. Our conclusions are based on new and existing data for T-II and the last interglacial that we collate onto a single, radiometrically constrained chronology. The HS11 cold episode punctuated T-II and coincided directly with a major deglacial meltwater pulse, which predominantly entered the North Atlantic Ocean and accounted for about 70 per cent of the glacial-interglacial sea-level rise. We conclude that, possibly in response to stronger insolation and CO2 forcing earlier in T-II, the relationship between climate and ice-volume changes differed fundamentally from that of T-I. In T-I, the major sea-level rise clearly post-dates Heinrich Stadial 1. We also find that HS11 coincided with sustained Antarctic warming, probably through a bipolar seesaw temperature response, and propose that this heat gain at high southern latitudes promoted Antarctic ice-sheet melting that fuelled the last interglacial sea-level peak. PMID:26062511

  7. Sea level during the Phanerozoic - what causes the fluctuations

    SciTech Connect

    Harrison, C.G.A.

    1985-01-01

    All possible causes of sea level change have been analyzed in order to explain the fall of sea level since the Cretaceous. The most important effect is the decrease in volume of the ridge crests due to an overall decrease in the rate of spreading since the Cretaceous. Other factors in order of decreasing importance are the reduction of the thermal bulge which accompanied the episode of Pacific volcanism between 110 and 70 my bp, the production of continental ice, the effect of the collision of India with Asia, and cooling of the ocean water. Sedimentation variation in the deep ocean has the effect of raising sea level a modest amount. The net variation in sea level during the past 80 million years has been a reduction by about 280 m after having allowed for isostatic adjustment of the ocean floor. This is considerably larger, than sea level calculated from the amount of continental flooding, and it is proposed that the discrepancy is due to a change in the continental hypsographic curve following the breakup of Pangea. This hypothesis is born out by studies of flooding during the Phanerozoic which reveal that flooding was very low at the beginning of the Mesozoic during a time of continental agglomeration, and high during much of the Paleozoic, which was a time of continental separation. In the Cambrian there is evidence for an increase in flooding with time, and at the beginning of the Cambrian flooding was not much greater than at the beginning of the Mesozoic, suggesting that it marked a time just subsequent to the break up of a super continent.

  8. Responses of coastal wetlands to rising sea level

    USGS Publications Warehouse

    Morris, J.T.; Sundareshwar, P.V.; Nietch, C.T.; Kjerfve, B.; Cahoon, D.R.

    2002-01-01

    Salt marsh ecosystems are maintained by the dominant macrophytes that regulate the elevation of their habitat within a narrow portion of the intertidal zone by accumulating organic matter and trapping inorganic sediment. The long-term stability of these ecosystems is explained by interactions among sea level, land elevation, primary production, and sediment accretion that regulate the elevation of the sediment surface toward an equilibrium with mean sea level. We show here in a salt marsh that this equilibrium is adjusted upward by increased production of the salt marsh macrophyte Spartina alterniflora and downward by an increasing rate of relative sea-level rise (RSLR). Adjustments in marsh surface elevation are slow in comparison to interannual anomalies and long-period cycles of sea level, and this lag in sediment elevation results in significant variation in annual primary productivity. We describe a theoretical model that predicts that the system will be stable against changes in relative mean sea level when surface elevation is greater than what is optimal for primary production. When surface elevation is less than optimal, the system will be unstable. The model predicts that there is an optimal rate of RSLR at which the equilibrium elevation and depth of tidal flooding will be optimal for plant growth. However, the optimal rate of RSLR also represents an upper limit because at higher rates of RSLR the plant community cannot sustain an elevation that is within its range of tolerance. For estuaries with high sediment loading, such as those on the southeast coast of the United States, the limiting rate of RSLR was predicted to be at most 1.2 cm/yr, which is 3.5 times greater than the current, long-term rate of RSLR.

  9. Bipolar seesaw control on last interglacial sea level

    NASA Astrophysics Data System (ADS)

    Marino, G.; Rohling, E. J.; Rodríguez-Sanz, L.; Grant, K. M.; Heslop, D.; Roberts, A. P.; Stanford, J. D.; Yu, J.

    2015-06-01

    Our current understanding of ocean-atmosphere-cryosphere interactions at ice-age terminations relies largely on assessments of the most recent (last) glacial-interglacial transition, Termination I (T-I). But the extent to which T-I is representative of previous terminations remains unclear. Testing the consistency of termination processes requires comparison of time series of critical climate parameters with detailed absolute and relative age control. However, such age control has been lacking for even the penultimate glacial termination (T-II), which culminated in a sea-level highstand during the last interglacial period that was several metres above present. Here we show that Heinrich Stadial 11 (HS11), a prominent North Atlantic cold episode, occurred between 135 +/- 1 and 130 +/- 2 thousand years ago and was linked with rapid sea-level rise during T-II. Our conclusions are based on new and existing data for T-II and the last interglacial that we collate onto a single, radiometrically constrained chronology. The HS11 cold episode punctuated T-II and coincided directly with a major deglacial meltwater pulse, which predominantly entered the North Atlantic Ocean and accounted for about 70 per cent of the glacial-interglacial sea-level rise. We conclude that, possibly in response to stronger insolation and CO2 forcing earlier in T-II, the relationship between climate and ice-volume changes differed fundamentally from that of T-I. In T-I, the major sea-level rise clearly post-dates Heinrich Stadial 1. We also find that HS11 coincided with sustained Antarctic warming, probably through a bipolar seesaw temperature response, and propose that this heat gain at high southern latitudes promoted Antarctic ice-sheet melting that fuelled the last interglacial sea-level peak.

  10. Mid- to Late Holocene Sea-Level Record in French Polynesia, South-Central Pacific

    NASA Astrophysics Data System (ADS)

    Hallmann, N.; Camoin, G.; Vella, C.; Eisenhauer, A.; Samankassou, E.; Botella, A.; Milne, G. A.; Fietzke, J.; Dussouillez, P.; Plaine, J.

    2014-12-01

    The Mid- to Late Holocene provides the opportunity to study the coastal response to sea-level change that has a similar amplitude (i.e., a few decimetres up to 1 m) to the sea-level rise that is likely to occur before the end of the current century. Furthermore, this time period provides an important baseline of natural climate variability prior to the industrial revolution. This study aims to reconstruct Mid- to Late Holocene relative sea-level change in French Polynesia by examining coral reef records from ten islands, which represent ideal settings for accurate sea-level change studies because: 1) they can be regarded as tectonically stable during the relevant period (slow subsidence), 2) they are located far from former ice sheets ('far-field'), 3) they are characterized by a low tidal amplitude, and 4) they cover a wide range of latitudes which produces significantly improved constraints on GIA (Glacial Isostatic Adjustment) model parameters. The accurate reconstruction of sea-level change relies on absolute U/Th dating of in situ coral colonies and their accurate positioning via GPS RTK (Real Time Kinematic) measurements with a vertical and horizontal precision of ± 2.5 cm and ~1 cm, respectively. We focus mainly on the analysis of coral microatolls, which are sensitive low-tide recorders, as their vertical accretion is limited by the water level. Their growth patterns allow the reconstruction of low-amplitude and high-frequency sea-level changes on centennial to sub-decadal time scales. A sea-level rise of less than ~1 m is documented between 6 and 3-3.5 ka, and is followed by a gradual fall in sea level that started around 2 ka and persisted until the past few centuries. The reconstructed sea-level curve therefore extends the Tahiti sea-level curve [Deschamps et al., 2012, Nature, 483, 559-564], and is in good agreement with a geophysical model tuned to fit far-field deglacial records [Bassett et al., 2005, Science, 309, 925-928].

  11. Coastal Vulnerability Due to Sea-level Rise Hazard in the Bangladesh Delta

    NASA Astrophysics Data System (ADS)

    Shum, Ck; Ballu, Valérie; Calmant, Stéphane; Duan, Jianbin; Guo, Junyi; Hossain, Fasial; Jenkins, Craig; Haque Khan, Zahirul; Kim, Jinwoo; Kuhn, Michael; Kusche, Jürgen; Papa, Fabrice; Tseng, Kuohsin; Wan, Junkun

    2014-05-01

    Approximately half of the world's population or 3.2 billion people lives within 200 km of coastlines and many of them in the world's deltaic plains. Sea-level rise, widely recognized as one of consequences resulting from anthropogenic climate change, has induced substantial coastal vulnerability globally and in particular, in the deltaic regions, such as coastal Bangladesh, and Yangtze Delta. Bangladesh, a low-lying, one of the most densely populated countries in the world located at the Bay of Bengal, is prone to transboundary monsoonal flooding, potentially aggravated by more frequent and intensified cyclones resulting from anthropogenic climate change. Sea-level rise, along with tectonic, sediment load and groundwater extraction induced land uplift/subsidence, have exacerbated Bangladesh's coastal vulnerability. Here we describe the physical science component of the integrated approach based on both physical and social sciences to address the adaption and potential mitigation of coastal Bangladesh vulnerability. The objective is to quantify the estimates of spatial varying sea-level trend separating the vertical motion of the coastal regions using geodetic and remote-sensing measurements (tide gauges, 1950-current; satellite altimetry, 1992-present, GRACE, 2003-present, Landsat/MODIS), reconstructed sea-level trends (1950-current), and GPS and InSAR observed land subsidence. Our goal is to conduct physically based robust projection of relative sea-level change at the end of the 21st century for the Bangladesh Delta to enable quantitative measures of social science based adaption and possible mitigation.

  12. The seasonal cycle and variability of sea level in the South China Sea

    NASA Astrophysics Data System (ADS)

    Amiruddin, A. M.; Haigh, I. D.; Tsimplis, M. N.; Calafat, F. M.; Dangendorf, S.

    2015-08-01

    The spatial and temporal characteristics of the seasonal sea level cycle in the South China Sea (SCS) and its forcing mechanisms are investigated using tide gauge records and satellite altimetry observations along with steric and meteorological data. The coastal mean annual amplitude of the seasonal cycle varies between zero and 24 cm, reaching a maximum between July and January. The maximum mean semiannual amplitude is 7 cm, peaking between March and June. Along the coast, the seasonal cycle accounts for up to 92% of the mean monthly sea level variability. Atmospheric pressure explains a significant portion of the seasonal cycle with dominant annual signals in the northern SCS, the Gulf of Thailand and the north-western Philippines Sea. The wind forcing is dominant on the shelf areas of the SCS and the Gulf of Thailand where a simple barotropic model forced by the local wind shows annual amplitudes of up to 27 cm. In the deep basin of the SCS, the Philippines Sea and the shallow Malacca Strait, the steric component is the major contributor with the maximum annual amplitudes reaching 15 cm. Significant variability in the seasonal cycle is found on a year-to-year basis. The annual and semiannual amplitudes vary by up to 63% and 45% of the maximum values, 15 cm and 11 cm, respectively. On average, stepwise regression analysis of contribution of different forcing factors accounts for 66% of the temporal variability of the annual cycle. The zonal wind was found to exert considerable influence in the Malacca Strait.

  13. Searching for Eustasy in Pliocene Sea-Level Records (Invited)

    NASA Astrophysics Data System (ADS)

    Raymo, M. E.; Hearty, P. J.; O'Leary, M.; Mitrovica, J.; Deconto, R.; Inglis, J. D.; Robinson, M. M.

    2010-12-01

    It is widely accepted that greenhouse gas-induced warming over the next few decades to centuries could lead to a rise in sea level due to melting ice caps. Yet despite the enormous social and economic consequences for society, our ability to predict the likelihood and location of future melting is hampered by an insufficient theoretical and historical understanding of ice sheet behavior in the past. Various lines of evidence suggest that CO2 levels in the mid-Pliocene were between 350-450 ppm, similar to today, and it is important that significant effort be made to confirm these estimates, especially in light of policy discussions that seek to determine a “safe” level of atmospheric CO2. Likewise, accurate estimates of mid-Pliocene sea levels are necessary if we are to better constrain Greenland and Antarctic ice sheet stability in a slightly warmer world. Current published estimates of mid-Pliocene sea level (during times of maximum insolation forcing) range from +5m to >+40m (relative to present) reflecting a huge range of uncertainty in the sensitivity of polar ice sheets, including the East Antarctic Ice Sheet, to a modest global warming. Accurate determination of the maximum mid-Pliocene sea level rise is needed if climate and ice sheet modelers are to better assess the robustness of models used to predict the effects of anthropogenic global warming. Pliocene ice volume/highstand estimates fall into two classes, those derived from geologic evidence of past high stands and those derived from geochemical proxies of ice-sensitive changes in ocean chemistry. Both methods have significant errors and uncertainties associated with them. Recent multidisciplinary work along the intra-plate continental margin of Roe Plain (~250 x 30 km) on the southern coastline of Western Australia provides additional constraints on sea level during the mid-Pliocene. Outcroppings of shore-proximal marine deposits are observed at two distinct elevations across the plain, +28 ± 2 m and +18 ± 2 m. Definitive sedimentary intertidal indications (e.g., concentrated concave down bivalves characteristic of a swash zone) and subtidal biofacies including articulated valves are found throughout the deposits and suggest the occurrence two distinct highstand events. Preliminary Sr-isotopes yield a broad range of mid to late Pliocene ages. These data will be discussed in light of possible ice volume, dynamic topography, and isostatic effects. Building on these data we present a strategy for improving the accuracy of mid Pliocene sea level estimates.

  14. A high resolution hindcast of the meteorological sea level component for Southern Europe: the GOS dataset

    NASA Astrophysics Data System (ADS)

    Cid, Alba; Castanedo, Sonia; Abascal, Ana J.; Menéndez, Melisa; Medina, Raúl

    2014-10-01

    Two sets of 62-year (1948-2009) and 21-year (1989-2009) high-resolution hindcasts of the meteorological sea level component have been developed for Southern Europe using the Regional Ocean Model System (ROMS) of Rutgers University. These new databases, named GOS 1.1 and GOS 2.1, are a valuable tool for a wide variety of studies, such as those related to a better understanding of sea level variability, flooding risk and coastal engineering studies. The model domain encloses Southern Europe, including the Mediterranean Sea and the Atlantic coast, with a horizontal resolution of 1/8° (~14 km). In order to study the effect of the atmospheric forcing resolution, ROMS is driven with two different regional atmospheric forcings: SeaWind I (30 km of horizontal resolution) and SeaWind II (15 km of horizontal resolution). Both are the result of a dynamical downscaling from global atmospheric reanalysis: NCEP global reanalysis and ERA-Interim global reanalysis, respectively. As a result, two surge data sets are obtained: GOS 1.1 (forced with SeaWind I) and GOS 2.1 (forced with SeaWind II). Surge elevations calculated by ROMS are compared with in situ measurements from tide gauges in coastal areas and with open ocean satellite observations. The validation procedure, testing outcomes from GOS 1.1 and GOS 2.1 against observations, shows the capability of the model to simulate accurately the sea level variation induced by the meteorological forcing. A description of the surge in terms of seasonality and long term trends is also made. The climate variability analysis reveals clear seasonal patterns in the Mediterranean Sea basins. A long-term negative trend for the period 1948-2009 is found, whilst positive trends are computed for the last 20 years (GOS 2.1).

  15. Sea level rise projections for Northern Europe under RCP8.5

    NASA Astrophysics Data System (ADS)

    Grinsted, Aslak; Jevrejeva, Svetlana; Riva, Riccardo; Dahl-Jensen, Dorthe

    2015-04-01

    We calculate regional projections of 21st century sea level rise in Northern Europe, focusing on the British Isles, the Baltic, and the North Sea. The input to the regional sea level projection is a probabilistic projection of the major components global sea level budget. Local sea level rise is partly compensated by vertical land movement from glacial isostatic adjustment. We explore the uncertainties beyond the likely range provided by IPCC, including the risk and potential rate of marine ice sheet collapse.

  16. A relative sea-level history for Arviat, Nunavut, and implications for Laurentide Ice Sheet thickness west of Hudson Bay

    NASA Astrophysics Data System (ADS)

    Simon, Karen M.; James, Thomas S.; Forbes, Donald L.; Telka, Alice M.; Dyke, Arthur S.; Henton, Joseph A.

    2014-07-01

    Thirty-six new and previously published radiocarbon dates constrain the relative sea-level history of Arviat on the west coast of Hudson Bay. As a result of glacial isostatic adjustment (GIA) following deglaciation, sea level fell rapidly from a high-stand of nearly 170 m elevation just after 8000 cal yr BP to 60 m elevation by the mid Holocene (~ 5200 cal yr BP). The rate of sea-level fall decreased in the mid and late Holocene, with sea level falling 30 m since 3000 cal yr BP. Several late Holocene sea-level measurements are interpreted to originate from the upper end of the tidal range and place tight constraints on sea level. A preliminary measurement of present-day vertical land motion obtained by repeat Global Positioning System (GPS) occupations indicates ongoing crustal uplift at Arviat of 9.3 ± 1.5 mm/yr, in close agreement with the crustal uplift rate inferred from the inferred sea-level curve. Predictions of numerical GIA models indicate that the new sea-level curve is best fit by a Laurentide Ice Sheet reconstruction with a last glacial maximum peak thickness of ~ 3.4 km. This is a 30-35% thickness reduction of the ICE-5G ice-sheet history west of Hudson Bay.

  17. Modelling sea level data from China and Malay-Thailand to estimate Holocene ice-volume equivalent sea level change

    NASA Astrophysics Data System (ADS)

    Bradley, Sarah L.; Milne, Glenn A.; Horton, Benjamin P.; Zong, Yongqiang

    2016-04-01

    This study presents a new model of Holocene ice-volume equivalent sea level (ESL), extending a previously published global ice sheet model (Bassett et al., 2005), which was unconstrained from 10 kyr BP to present. This new model was developed by comparing relative sea level (RSL) predictions from a glacial isostatic adjustment (GIA) model to a suite of Holocene sea level index points from China and Malay-Thailand. Three consistent data-model misfits were found using the Bassett et al. (2005) model: an over-prediction in the height of maximum sea level, the timing of this maximum, and the temporal variation of sea level from the time of the highstand to present. The data-model misfits were examined for a large suite of ESL scenarios and a range of earth model parameters to determine an optimum model of Holocene ESL. This model is characterised by a slowdown in melting at ∼7 kyr BP, associated with the final deglaciation of the Laurentide Ice Sheet, followed by a continued rise in ESL until ∼1 kyr BP of ∼5.8 m associated with melting from the Antarctic Ice Sheet. It was not possible to identify an earth viscosity model that provided good fits for both regions; with the China data preferring viscosity values in the upper mantle of less than 1.5 × 1020 Pa s and the Malay-Thailand data preferring greater values. We suggest that this inference of a very weak upper mantle for the China data originates from the nearby subduction zone and Hainan Plume. The low viscosity values may also account for the lack of a well-defined highstand at the China sites.

  18. Late Holocene sea- and land-level change on the U.S. southeastern Atlantic Coast

    USGS Publications Warehouse

    Kemp, Andrew C.; Bernhardt, Christopher E.; Horton, Benjamin P.; Kopp, Robert E.; Vane, Christopher H.; Peltier, W. Richard; Hawkes, Andrea D.; Donnelly, Jeffrey P.; Parnell, Andrew C.; Cahill, Niamh

    2015-01-01

    Late Holocene relative sea-level (RSL) reconstructions can be used to estimate rates of land-level (subsidence or uplift) change and therefore to modify global sea-level projections for regional conditions. These reconstructions also provide the long-term benchmark against which modern trends are compared and an opportunity to understand the response of sea level to past climate variability. To address a spatial absence of late Holocene data in Florida and Georgia, we reconstructed ~ 1.3 m of RSL rise in northeastern Florida (USA) during the past ~ 2600 years using plant remains and foraminifera in a dated core of high salt-marsh sediment. The reconstruction was fused with tide-gauge data from nearby Fernandina Beach, which measured 1.91 ± 0.26 mm/year of RSL rise since 1900 CE. The average rate of RSL rise prior to 1800 CE was 0.41 ± 0.08 mm/year. Assuming negligible change in global mean sea level from meltwater input/removal and thermal expansion/contraction, this sea-level history approximates net land-level (subsidence and geoid) change, principally from glacio-isostatic adjustment. Historic rates of rise commenced at 1850–1890 CE and it is virtually certain (P = 0.99) that the average rate of 20th century RSL rise in northeastern Florida was faster than during any of the preceding 26 centuries. The linearity of RSL rise in Florida is in contrast to the variability reconstructed at sites further north on the U.S. Atlantic coast and may suggest a role for ocean dynamic effects in explaining these more variable RSL reconstructions. Comparison of the difference between reconstructed rates of late Holocene RSL rise and historic trends measured by tide gauges indicates that 20th century sea-level trends along the U.S. Atlantic coast were not dominated by the characteristic spatial fingerprint of melting of the Greenland Ice Sheet.

  19. Seasonal variability in global sea level observed with Geosat altimetry

    NASA Technical Reports Server (NTRS)

    Zlotnicki, V.; Fu, L.-L.; Patzert, W.

    1989-01-01

    Time changes in global mesoscale sea level variances were observed with satellite altimetry between November 1986 and March 1988, showing significant, geographically coherent seasonal patterns. The NE Pacific and NE Atlantic variances show the most reliable patterns, higher than their yearly averages in both the fall and winter. The response to wind forcing appears as the major contributor to the NE Pacific and Atlantic signals; errors in the estimated inverse barometer response due to errors in atmospheric pressure, residual orbit errors, and errors in sea state bias are evaluated and found to be negligible contributors to this particular signal. The equatorial regions also show significant seasonal patterns, but the uncertainties in the wet tropospheric correction prevent definitive conclusions. The western boundary current changes are very large but not statistically significant. Estimates of the regression coefficient between sea level and significant wave height, an estimate of the sea state bias correction, range between 2.3 and 2.9 percent and vary with the type of orbit correction applied.

  20. Coherent sea level variability on the North Atlantic western boundary

    NASA Astrophysics Data System (ADS)

    Thompson, P. R.; Mitchum, G. T.

    2014-09-01

    Interannual to decadal sea level variability on the North Atlantic western boundary is surprisingly coherent over substantial distances stretching from the Caribbean to Nova Scotia. The physical mechanisms responsible for this basin-scale, low-frequency coherence are explored in a diagnosis of simulated ocean fields from GECCO, which reproduces the observations to good approximation. Coastal sea level variability on the western boundary is known to be influenced by meridional divergence in the boundary current resulting in a geostrophic tilting of the sea surface. This mechanism is found to be of leading order along some stretches of the boundary, but it does not account for the coherence spanning the western North Atlantic. Instead, the coherence along the entire boundary is accounted for by vertical divergence resulting in the uniform rise and fall of the sea surface west of the 295°E meridian. The vertical divergence is found to be due to net vertically integrated zonal transport across this meridian resulting from meridional variation in the Sverdrup transport over the basin interior.

  1. Late Holocene sea level variability and Atlantic Meridional Overturning Circulation

    NASA Astrophysics Data System (ADS)

    Cronin, T. M.; Farmer, J.; Marzen, R. E.; Thomas, E.; Varekamp, J. C.

    2014-08-01

    Pre-twentieth century sea level (SL) variability remains poorly understood due to limits of tide gauge records, low temporal resolution of tidal marsh records, and regional anomalies caused by dynamic ocean processes, notably multidecadal changes in Atlantic Meridional Overturning Circulation (AMOC). We examined SL and AMOC variability along the eastern United States over the last 2000 years, using a SL curve constructed from proxy sea surface temperature (SST) records from Chesapeake Bay, and twentieth century SL-sea surface temperature (SST) relations derived from tide gauges and instrumental SST. The SL curve shows multidecadal-scale variability (20-30 years) during the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA), as well as the twentieth century. During these SL oscillations, short-term rates ranged from 2 to 4 mm yr-1, roughly similar to those of the last few decades. These oscillations likely represent internal modes of climate variability related to AMOC variability and originating at high latitudes, although the exact mechanisms remain unclear. Results imply that dynamic ocean changes, in addition to thermosteric, glacio-eustatic, or glacio-isostatic processes are an inherent part of SL variability in coastal regions, even during millennial-scale climate oscillations such as the MCA and LIA and should be factored into efforts that use tide gauges and tidal marsh sediments to understand global sea level rise.

  2. Mean sea-level height variations in the Central Mediterranean

    NASA Astrophysics Data System (ADS)

    Zerbini, Susanna; Bruni, Sara; Errico, Maddalena; Petracca, Fernanda; Raicich, Fabio; Santi, Efisio

    2015-04-01

    The Italian tide gauge network has experienced difficulties during last century. However, historical time series, starting from the end of the ninetieth century, are available in the PSMSL data base (Permanent Service for Mean Sea Level, http://www.psmsl.org/data/). Data from the early 1980s can also be obtained from the data base of ISPRA (Istituto Superiore per la Protezione e la Ricerca Ambientale, http://www.mareografico.it). In 1998, the Italian national tide gauge network (Rete Mareografica Nazionale - RMN) was completely restructured; it consists of 36 homogeneously distributed stations providing measurements sampled every 10 minutes. We have analyzed both the historical and the recent time series of a sub set of stations located in the Tyrrhenian area by using the Empirical Orthogonal Functions (EOF) approach. The EOF analysis allows describing one data set as a linear combination of orthogonal components, or modes, that depend on position only, while the linear combination coefficients are functions of time only. Each mode is associated to a percentage of the total variance of the original data set, which accounts for the relative importance of the corresponding mode of variability. The aim of this work is to identify common modes which could possibly be related to wide area crustal deformation and/or to climatic fluctuations, such as the inverted barometer effect.

  3. Holocene Sea-Level Database For The Caribbean Region

    NASA Astrophysics Data System (ADS)

    Khan, N. S.; Horton, B.; Engelhart, S. E.; Peltier, W. R.; Scatena, F. N.; Vane, C. H.; Liu, S.

    2013-12-01

    Holocene relative sea-level (RSL) records from far-field locations are important for understanding the driving mechanisms controlling the nature and timing of the mid-late Holocene reduction in global meltwaters and providing background rates of late Holocene RSL change with which to compare the magnitude of 20th century RSL rise. The Caribbean region has traditionally been considered far-field (i.e., with negligible glacio-isostatic adjustment (GIA) influence), although recent investigations indicate otherwise. Here, we consider the spatial variability in glacio-isostatic, tectonic and local contributions on RSL records from the circum-Caribbean region to infer a Holocene eustatic sea-level signal. We have constructed a database of quality-controlled, spatially comprehensive, Holocene RSL observations for the circum-Caribbean region. The database contains over 500 index points, which locate the position of RSL in time and space. The database incorporates sea-level observations from a latitudinal range of 5N to 25N and longitudinal range of 55W to 90W. We include sea-level observations from 11 ka BP to present, although the majority of the index points in the database are younger than 8 ka BP. The database is sub-divided into 13 regions based on the distance from the former Laurentide Ice Sheet and regional tectonic setting. The index points were primarily derived from mangrove peat deposits, which in the Caribbean form in the upper half of the tidal range, and corals (predominantly Acropora palmata), the growth of which is constrained to the upper 5 m of water depth. The index points are classified on the basis of their susceptibility to compaction (e.g., intercalated, basal). The influence of temporal changes in tidal range on index points is also considered. The sea-level reconstructions demonstrate that RSL did not exceed the present height (0 m) during the Holocene in the majority of locations, except at sites in Suriname/Guayana and possibly Trinidad located furthest away from the former Laurentide Ice Sheet. Rates of RSL change were highest during the early Holocene and have decreased over time due primarily to the reduction of ice equivalent meltwater input. Sea-level observations are compared to predictions from glacio-isostatic adjustment (GIA) models, and the relative influence of tectonic vertical land movements on the RSL records in each region is assessed. Background rates of late Holocene RSL change are also compared to local tide gauge records to determine excess rates of 20th century RSL rise.

  4. Implications of Rising Sea Level on Everglades Restoration

    NASA Astrophysics Data System (ADS)

    Wanless, H. R.

    2008-05-01

    The strong likelihood of a significant rise in sea level during this century must be incorporated into the design of the Comprehensive Everglades Restoration Plan (CERP) and its execution. With a warming Arctic and increased wind shear in the waters adjacent to Antarctica, accelerated ice melt of both Greenland and Antarctica has begun. With positive feedbacks, this melt appears irreversible on the century scale. Scientists of the Miami-Dade County Climate Change Task Force project that a global rise of sea level of at least 0.9-1.5 meters (3-5 feet) will occur by the end of the century. This anticipated rise will diminish the value of CERP unless (a) the design thoroughly incorporates a realistic sea level rise scenario and (b) there is a refocus of CERP's design to optimize water flow for wetland-community peat growth with the purpose of retarding saline encroachment. The goals of Everglades restoration must become (1) to provide an increase in water flowing at a gradually increasing elevation to permit rapid accumulation of robust organic peat beneath the freshwater wetland and (2) to actively manage the coastal mangrove wetland (e.g., aid hurricane recovery) to help it maintain a robust upwards-building peat margin. If this is done, the central and northern Everglades may survive as a healthy wetland habitat and provide fresh groundwater resources well into the next century. Actively building freshwater and mangrove peat and a dependable supply of freshwater are both critical to retarding saline encroachment up the Everglades depression. Without these, a 1.5 meter rise in sea level could move saline water nearly to Lake Okeechobee. Critical research questions and changes in management need to be addressed for this to succeed. The communities and conditions for optimal freshwater peat buildup must be documented and demonstrated. New management strategies must be designed and maintained to encourage rapid recovery of mangrove forests destroyed by hurricanes, including within National Parks. Water used by south Florida communities (agriculture, industry and residential) should be cleaned and recycled back into the aquifer system. Hydrologic modeling needs to focus on those areas along the Everglades' eastern margin most prone to saline encroachment with rising sea levels so as to design barriers (limited use of levees and pumping to maintain freshwater head) that will retard intrusion. The reality of a significantly rising sea level must be incorporated into all aspects of research, design and monitoring of CERP. Adaptive management must be reactivated and maintained as a foundation of this critically important national restoration plan.

  5. Interannual to decadal variation of spring sea level anomaly in the western South China Sea

    NASA Astrophysics Data System (ADS)

    Qiu, Fuwen; Fang, Wendong; Pan, Aijun; Cha, Jing; Zhang, Shanwu; Huang, Jiang

    2016-04-01

    Satellite observations of sea level anomalies (SLA) from January 1993 to December 2012 are used to investigate the interannual to decadal changes of the boreal spring high SLA in the western South China Sea (SCS) using the Empirical Orthogonal Function (EOF) method. We find that the SLA variability has two dominant modes. The Sea Level Changing Mode (SLCM) occurs mainly during La Niña years, with high SLA extension from west of Luzon to the eastern coast of Vietnam along the central basin of the SCS, and is likely induced by the increment of the ocean heat content. The Anticyclonic Eddy Mode (AEM) occurs mainly during El Niño years and appears to be triggered by the negative wind curl anomalies within the central SCS. In addition, the spring high SLA in the western SCS experienced a quasi-decadal change during 1993-2012; in other words, the AEM predominated during 1993-1998 and 2002-2005, while the La Niña-related SLCM prevailed during 1999-2001 and 2006-2012. Moreover, we suggest that the accelerated sea level rise in the SCS during 2005-2012 makes the SLCM the leading mode over the past two decades.

  6. Temporal scaling behavior of sea-level change in Hong Kong - Multifractal temporally weighted detrended fluctuation analysis

    NASA Astrophysics Data System (ADS)

    Zhang, Yuanzhi; Ge, Erjia

    2013-01-01

    The rise in global sea levels has been recognized by many scientists as an important global research issue. The process of sea-level change has demonstrated a complex scaling behavior in space and time. Large numbers of tide gauge stations have been built to measure sea-level change in the North Pacific Ocean, Indian Ocean, North Atlantic Ocean, and Antarctic Ocean. Extensive studies have been devoted to exploring sea-level variation in Asia concerning the Bohai Gulf (China), the Yellow Sea (China), the Mekong Delta (Thailand), and Singapore. Hong Kong, however, a mega city with a population of over 7 million situated in the mouth of the Pear River Estuary in the west and the South China Sea in the east, has yet to be studied, particularly in terms of the temporal scaling behavior of sea-level change. This article presents an approach to studying the temporal scaling behavior of sea-level change over multiple time scales by analyzing the time series of sea-level change in Tai Po Kou, Tsim Bei Tsui, and Quarry Bay from the periods of 1964-2010, 1974-2010, and 1986-2010, respectively. The detection of long-range correlation and multi-fractality of sea-level change seeks answers to the following questions: (1) Is the current sea-level rise associated with and responsible for the next rise over time? (2) Does the sea-level rise have specific temporal patterns manifested by multi-scaling behaviors? and (3) Is the sea-level rise is temporally heterogeneous in the different parts of Hong Kong? Multi-fractal temporally weighted de-trended fluctuation analysis (MF-TWDFA), an extension of multi-fractal de-trended fluctuation analysis (MF-DFA), has been applied in this study to identify long-range correlation and multi-scaling behavior of the sea-level rise in Hong Kong. The experimental results show that the sea-level rise is long-range correlated and multi-fractal. The temporal patterns are heterogeneous over space. This finding implies that mechanisms associated with the local ecological environment, hydrodynamic and morphodynamic processes, and human activities might have driven a distinct sea-level rise in Hong Kong.

  7. Low sea-level stand emplacement of megaturbidites in the western and eastern Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Rothwell, R. G.; Reeder, M. S.; Anastasakis, G.; Stow, D. A. V.; Thomson, J.; Kähler, G.

    2000-09-01

    Piston cores from the Balearic and Herodotus Abyssal Plains in the Mediterranean Sea show that the Late Pleistocene to Holocene sedimentary sequence is dominated by turbidite muds. On each plain, one turbidite bed is conspicuous by its thickness, and this bed can be correlated basinwide on the basis of geochemical compositional analysis and its apparent correspondence with a distinct acoustically transparent layer on high-resolution seismic records. These megabeds on the two plains represent megaturbidites of very large volume (300-600 km 3 each) and are shown by AMS radiocarbon dating to have been emplaced during the last low stand of sea-level at the height of the last glacial maximum. The megabed on the Balearic Abyssal Plain is derived from the southern European margin and is the main sedimentation event over the last 120 ka. It emplaced as much material as was deposited by smaller flows during the previous 25 ka. Sedimentation rate curves for the Balearic Abyssal Plain show that falling sea-level correlates with increased terrigenous deposition, and that gross sedimentation rates in the basin increased as sea level fell from 120-18 ka due to more frequent emplacement of distal turbidites. The Herodotus Abyssal Plain megabed is derived from the Libyan-Egyptian continental shelf west of the Nile Delta and was the dominant sedimentation event in this basin during the past 60 kyr. High-resolution seismic profiles from the Ionian and Sirte Abyssal Plains in the central Mediterranean also suggest possible low sea-level emplacement of megabeds in these regions. Available evidence suggests widespread emplacement of megaturbidites throughout the Mediterranean at the last glacial maximum. Although the triggering mechanisms for these events remain speculative, catastrophic destabilisation of the margin after a long period of accumulation with an increased rate of sediment supply is suggested.

  8. Holocene changes in sea level: Evidence in Micronesia

    USGS Publications Warehouse

    Shepard, F.P.; Curray, Joseph R.; Newman, W.A.; Bloom, A.L.; Newell, N.D.; Tracey, J.I., Jr.; Veeh, H.H.

    1967-01-01

    Investigation of 33 islands, scattered widely across the Caroline and Marshall Island groups in the Central Pacific revealed no emerged reefs in which corals had unquestionably formed in situ, or other direct evidence of postglacial high stands of sea level. Low unconsolidated rock terraces and ridges of reef-flat islands, mostly lying between tide levels, were composed of rubble conglomerates; carbon-14 dating of 11 samples from the conglomerates so far may suggest a former slightly higher sea level (nine samples range between 1890 and 3450 and one approaches 4500 years ago). However, recent hurricanes have produced ridges of comparable height and material, and in the same areas relics from World War II have been found cemented in place. Thus these datings do not in themselves necessarily indicate formerly higher sea levels. Rubble tracts are produced by storms under present conditions without any change in datum, and there seems to be no compelling evidence that they were not so developed during various periods in the past.

  9. Coastal sea level variability in the eastern English Channel: Potentialities for future SWOT applicability

    NASA Astrophysics Data System (ADS)

    Turki, Imen; Laignel, Benoit; Chevalier, Laetitia; Costa, Stephane

    2014-05-01

    Scientists and engineers need to understand the sea level variability in order to provide better estimates of the sea level rise for coastal defense using tide gauges and radar altimetry missions. The natural limitation of the tide gauge records is their geographical sparsity and confinement to coastlines. The future Surface Water and Ocean Topography (SWOT) mission will be launched in 2015 over a period of 5 years and will be designated to address this issue. This research was carried out in the framework of the program Surface Water and Ocean Topography (SWOT) which is a partnership between NASA and CNES. Using a series of statistical analyses, we point to characterize the sea level variability in the eastern English Channel (western France) from four tide gauges in Dunkirk, Dieppe, Le Havre and Cherbourg for the period 1964-2012. To assess the extent to which tide gauge point observations represent tide gauge data, we compare tide gauge records to SWOT measurements in their vicinity. Results have shown that the bimodality of the sea level, provided by the distribution analysis, can be reproduced by SWOT measurements with an overestimation of both modes and also the extreme values. The rate of the linear regression was also overestimated from 1.7-4 mm/yr to 2.6-5.4 mm/yr. The continuous wavelet transform of sea level records has shown the large-scale variability of annual (1-year band) and interannual cycles (2-6- and 6-12-year bands) in sea level, which can be explained by oceanographic and hydrological factors. High frequency dynamics of the sea level variability at short time-scales were extracted from SWOT measurements. They provide a good survey of the surge events (band of 3-4 months) and the spring-neap tidal cycle (band of 28 days). Then, tide gauges should be used in conjunction with satellite data to infer the full time-scale variability. Further studies are needed to refine the SWOT applicability in coastal areas. Key words: coastal zone, sea level variability, tide gauges, virtual SWOT measurements

  10. The gyre-scale circulation of the North Atlantic and sea level at Brest

    NASA Astrophysics Data System (ADS)

    Woodworth, P. L.; Pouvreau, N.; Wöppelmann, G.

    2009-10-01

    The relationship between the gyre-scale circulation of the North Atlantic, represented by air pressure near to the centre of the sub-tropical gyre, and sea level measured at the eastern boundary of the ocean has been investigated using records commencing in the middle of the 18th century. These time series are twice as long as those employed in an earlier study of this relationship. Near-continuous values of annual mean sea level and mean high water from Brest, and air pressure fields for the eastern North Atlantic derived from terrestrial instrumental pressure records and ship logbook information, have been used to demonstrate that sea level on the eastern boundary does indeed appear to be related to air pressure at the centre of the gyre, confirming the earlier conclusions but on much longer timescales. This relationship can explain at least part of the century timescale accelerations in European sea level records obtained from tide gauge and saltmarsh data. This finding has important implications for interpretation of the observed sea level rise and acceleration on the European Atlantic coast, suggesting that redistribution of water could play an important role instead of (or as well as) change in ocean volume.

  11. The gyre-scale circulation of the North Atlantic and sea level at Brest

    NASA Astrophysics Data System (ADS)

    Woodworth, P. L.; Pouvreau, N.; Wöppelmann, G.

    2010-02-01

    The relationship between the gyre-scale circulation of the North Atlantic, represented by air pressure near to the centre of the sub-tropical gyre, and sea level measured at the eastern boundary of the ocean has been investigated using records commencing in the middle of the 18th century. These time series are twice as long as those employed in an earlier study of this relationship. Near-continuous values of annual mean sea level and mean high water from Brest, and air pressure fields for the eastern North Atlantic derived from terrestrial instrumental pressure records and ship logbook information, have been used to demonstrate that sea level on the eastern boundary does indeed appear to be related to air pressure at the centre of the gyre (subject to reservations concerning short sub-sections of data near to the ends of the records). These findings confirm the earlier conclusions but over much longer timescales. This relationship can explain at least part of the century timescale accelerations in European sea level records obtained from tide gauge and saltmarsh data. This finding has important implications for interpretation of the observed sea level rise and acceleration on the European Atlantic coast, suggesting that redistribution of water could play an important role instead of (or as well as) change in ocean volume.

  12. US power plant sites at risk of future sea-level rise

    NASA Astrophysics Data System (ADS)

    Bierkandt, R.; Auffhammer, M.; Levermann, A.

    2015-12-01

    Unmitigated greenhouse gas emissions may increase global mean sea-level by about 1 meter during this century. Such elevation of the mean sea-level enhances the risk of flooding of coastal areas. We compute the power capacity that is currently out-of-reach of a 100-year coastal flooding but will be exposed to such a flood by the end of the century for different US states, if no adaptation measures are taken. The additional exposed capacity varies strongly among states. For Delaware it is 80% of the mean generated power load. For New York this number is 63% and for Florida 43%. The capacity that needs additional protection compared to today increases by more than 250% for Texas, 90% for Florida and 70% for New York. Current development in power plant building points towards a reduced future exposure to sea-level rise: proposed and planned power plants are less exposed than those which are currently operating. However, power plants that have been retired or canceled were less exposed than those operating at present. If sea-level rise is properly accounted for in future planning, an adaptation to sea-level rise may be costly but possible.

  13. Geologic effects and coastal vulnerability to sea-level rise, erosion, and storms

    USGS Publications Warehouse

    Williams, S.J.; Gutierrez, B.T.; Thieler, E.R.; Pendleton, E.

    2008-01-01

    A combination of natural and human factors are driving coastal change and making coastal regions and populations increasingly vulnerable. Sea level, a major agent of coastal erosion, has varied greatly from -120 m below present during glacial period low-stands to + 4 to 6 m above present during interglacial warm periods. Geologic and tide gauge data show that global sea level has risen about 12 to 15 cm during the past century with satellite measurements indicating an acceleration since the early 1990s due to thermal expansion and ice-sheet melting. Land subsidence due to tectonic forces and sediment compaction in regions like the mid-Atlantic and Louisiana increase the rate of relative sea-level rise to 40 cm to 100 cm per century. Sea- level rise is predicted to accelerate significantly in the near future due to climate change, resulting in pervasive impacts to coastal regions and putting populations increasingly at risk. The full implications of climate change for coastal systems need to be understood better and long-term plans are needed to manage coasts in order to protect natural resources and mitigate the effects of sea-level rise and increased storms on human infrastructure. Copyright ASCE 2008.

  14. Tidal marsh stability in the face of human impacts and sea level rise

    NASA Astrophysics Data System (ADS)

    Kirwan, M. L.

    2014-12-01

    Coastal populations and marshes have been intertwined for centuries, where humans both influence and depend on the enormous ecosystem services that marshes provide. Although marshes have long been considered vulnerable to climate change, recent work identifies fascinating feedbacks between plant growth and geomorphology that enable them to actively resist sea level rise. Here, we will review existing literature and provide new data to examine how humans alter these feedbacks. Measurements of accretion and elevation change suggest that most marshes will survive present day sea level rise rates by building vertically. Numerical models predict that these marshes will survive moderate accelerations in the rate of sea level in places where dams do not limit sediment delivery to the coast. However, these results also suggest that marsh survival under faster accelerations in sea level will depend on their ability to migrate inland. Marsh transgression into uplands is influenced not only by topography, but also by human land use and decisions to harden shorelines. Preliminary numerical model experiments will be used to explore how basic biophysical and anthropogenic drivers determine whether sea level change will lead to marsh loss (erosion+drowning > transgression), marsh expansion (transgression > erosion), or dynamic equilibrium (transgression = erosion).

  15. Mass and volume contributions to twentieth-century global sea level rise.

    PubMed

    Miller, Laury; Douglas, Bruce C

    2004-03-25

    The rate of twentieth-century global sea level rise and its causes are the subjects of intense controversy. Most direct estimates from tide gauges give 1.5-2.0 mm yr(-1), whereas indirect estimates based on the two processes responsible for global sea level rise, namely mass and volume change, fall far below this range. Estimates of the volume increase due to ocean warming give a rate of about 0.5 mm yr(-1) (ref. 8) and the rate due to mass increase, primarily from the melting of continental ice, is thought to be even smaller. Therefore, either the tide gauge estimates are too high, as has been suggested recently, or one (or both) of the mass and volume estimates is too low. Here we present an analysis of sea level measurements at tide gauges combined with observations of temperature and salinity in the Pacific and Atlantic oceans close to the gauges. We find that gauge-determined rates of sea level rise, which encompass both mass and volume changes, are two to three times higher than the rates due to volume change derived from temperature and salinity data. Our analysis supports earlier studies that put the twentieth-century rate in the 1.5-2.0 mm yr(-1) range, but more importantly it suggests that mass increase plays a larger role than ocean warming in twentieth-century global sea level rise. PMID:15042085

  16. Local diagnostics to estimate density-induced sea level variations over topography and along coastlines

    NASA Astrophysics Data System (ADS)

    Bingham, R. J.; Hughes, C. W.

    2012-01-01

    In the open ocean, sea level variability is primarily steric in origin. Steric sea level is given by the depth integral of the density field, raising the question of how tide gauges, which are situated in very shallow water, feel deep ocean variability. Here this question is examined in a high-resolution global ocean model. By considering a series of assumptions we show that if we wish to reconstruct coastal sea level using only local density information, then the best assumption we can make is one of no horizontal pressure gradient, and therefore no geostrophic flow, at the seafloor. Coastal sea level can then be determined using density at the ocean's floor. When attempting to discriminate between mass and volume components of sea level measured by tide gauges, the conventional approach is to take steric height at deep-ocean sites close to the tide gauges as an estimate of the steric component. We find that with steric height computed at 3000 m this approach only works well in the equatorial band of the Atlantic and Pacific eastern boundaries. In most cases the steric correction can be improved by calculating steric height closer to shore, with the best results obtained in the depth range 500-1000 m. Yet, for western boundaries, large discrepancies remain. Our results therefore suggest that on time scales up to about 5 years, and perhaps longer, the presence of boundary currents means that the conventional steric correction to tide gauges may not be valid in many places.

  17. Vitamin A deficiency and hepatic retinol levels in sea otters, Enhydra lutris.

    PubMed

    St Leger, Judy A; Righton, Alison L; Nilson, Erika M; Fascetti, Andrea J; Miller, Melissa A; Tuomi, Pamela A; Goertz, Caroline E C; Puschner, Birgit

    2011-03-01

    Vitamin A deficiency has rarely been reported in captive or free-ranging wildlife species. Necropsy findings in two captively housed southern sea otters (Enhydra lutris nereis) included irregular thickening of the calvaria characterized by diffuse hyperostoses on the internal surface. One animal also had moderate squamous metaplasia of the seromucinous glands of the nose. There was no measurable retinol in the liver of either sea otter. For comparison, hepatic retinol concentration was determined for 23 deceased free-ranging southern and northern (Enhydra lutris kenyoni) sea otters from California and Alaska. Free-ranging otters were found to have similar hepatic retinol concentrations (316 +/- 245 mg/kg wet weight) regardless of their location and subspecies. All of these values were significantly higher than the levels in the affected animals. Consumption of a diet with very low vitamin A concentrations and noncompliance in daily supplementation are hypothesized as the causes of vitamin A deficiency in these two sea otters. PMID:22946376

  18. PERSPECTIVE: The tripping points of sea level rise

    NASA Astrophysics Data System (ADS)

    Hecht, Alan D.

    2009-12-01

    When President Nixon created the US Environmental Protection Agency (EPA) in 1970 he said the environment must be perceived as a single, interrelated system. We are nowhere close to achieving this vision. Jim Titus and his colleagues [1] highlight one example of where one set of regulations or permits may be in conflict with another and where regulations were crafted in the absence of understanding the cumulative impact of global warming. The issue here is how to deal with the impacts of climate change on sea level and the latter's impact on wetland polices, clean water regulations, and ecosystem services. The Titus paper could also be called `The tripping points of sea level rise'. Titus and his colleagues have looked at the impact of such sea level rise on the east coast of the United States. Adaptive responses include costly large- scale investment in shore protection (e.g. dikes, sand replenishment) and/or ecosystem migration (retreat), where coastal ecosystems move inland. Shore protection is limited by available funds, while ecosystem migrations are limited by available land use. The driving factor is the high probability of sea level rise due to climate change. Estimating sea level rise is difficult because of local land and coastal dynamics including rising or falling land areas. It is estimated that sea level could rise between 8 inches and 2 feet by the end of this century [2]. The extensive data analysis done by Titus et al of current land use is important because, as they observe, `property owners and land use agencies have generally not decided how they will respond to sea level rise, nor have they prepared maps delineating where shore protection and retreat are likely'. This is the first of two `tripping points', namely the need for adaptive planning for a pending environmental challenge that will create economic and environment conflict among land owners, federal and state agencies, and businesses. One way to address this gap in adaptive management, according to Titus et al, is for communities to develop a common vision about which lands will be protected and which lands will yield to the rising sea, similar to the way land use plans identify commercial, residential, agricultural, and conservation lands. The supplementary material in their paper (as well as a related web site suggested by the peer review process of this journal) provides maps that depict the likelihood of shore protection based on existing land use data and the assessment of the local governments. Such maps, they suggest, might be used as a starting point to promote dialogue within communities about which lands should be protected and which lands are allowed to become submerged. A second tripping point relates to conflict between existing environmental laws and their collective ability to respond to the impacts of global warming. For example, property owners are automatically issued permits for construction of hard shore-protection structures (e.g. bulkheads and revetments) without an assessment of their environmental impact. Normally, under the Clean Water Act, the impact of each permit is assessed separately, but there is a special expedited process for activities with no cumulative impact. The Corps of Engineers concluded that shore protection does not have a cumulative impact, and that might be true if shore erosion was rare and stable shores the general rule. But once we recognize that the sea level is rising, then shore erosion becomes the general rule and a cumulative impact is likely. Under the National Environmental Protection Act (NEPA), cumulative impacts have been defined as `the impacts of an activity ``added to other past present and reasonably future actions'' regardless of who takes the other actions'. If the NEPA were actually evoked, it would considerably delay permit approvals and substantially impact the Corps of Engineers' process for issuing permits. The potential impact of sea level rise clearly requires a holistic approach to coastal management in which options for shore protection or retreats are clearly identified and where economic, ecosystem and social impacts can be clearly evaluated. At stake are both the future of wetlands that provide important ecosystem services and the safety and sustainability of our coastal communities. This is a huge challenge requiring adequate data, long-term planning, federal-state cooperation, and integration of environmental laws. The time is at hand to assess a business-as-usual response to sea level rise or to explore a more holistic and integrated approach. President Obama has said: `The threat from climate change is serious, it is urgent, and it is growing. Our generation's response to this challenge will be judged by history, for if we fail to meet it—boldly, swiftly, and together—we risk consigning future generations to an irreversible catastrophe' [3]. Though the President was talking about action to reduce emissions of greenhouse gases, cooperation to address the consequences of rising sea level and changing climate is just as urgent. References [1] Titus J G et al 2009 State and local governments plan for development of most land vulnerable to rising sea level along the US Atlantic coast Environ. Res. Lett. 4 044008 [2] US Global Change Research Program 2009 Global Climate Change Impacts in the United States (June 2009) [3] www.whitehouse.gov/the_press_office/Remarks-by-the-President-at-UN-Secretary-General-Ban-Ki-moons-Climate-Change-Summit/

  19. Global increasing of mean sea level and erroneous treatment of a role of thermal factors

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.

    2009-04-01

    Satellite methods of studies of the ocean surface - methods of altimetry - have been obtained intensive development in the last decades (since 1993). However, altimetry studies with the help of special satellites such as TOPEX-Poseidon not only have not cleared up understanding of the phenomenon of increase of sea level (SLR), but have even more confused and without that a complex question on the reasons of increase of sea level. Appeared, that classical determinations of average velocity of increase of sea level on coastal observations (1.4-1.7 mm / yr) approximately for 0.8-1.0 mm / yr it is less, rather than by modern satellite determinations of satellites TOPEX - Poseidon etc. (2.5 - 2.8 mm / yr). On the basis of the data of altimetry observations of TOPEX-Poseidon and Jason for the period 1993-2003 for geocentric velocity of increase of sea level (of global ocean) the value 2.8+/-0.4 mm / yr [1] has been obtained. In the given report the full answer is actually is given to a question put by leading experts on research of the sea level: "The TOPEX/Poseidon and Jason satellite altimeter missions provided a 12 year record of sea level change, which show increase of global mean sea level of 2.8+/-0.4 mm/yr, with considerable geographic variation. An important question for climate studies is to determine the cause of this change - specifically how much of the change is due to steric (heating) versus eustatic (runoff, melting ice, etc.) contribution?" [1]. There is, a big value of average velocity of increase of the sea level on the satellite data, it is possible to explain only by kinematical effect in data of observations. The motion of the satellite "is concerned" to the centre of mass of our planet, and its position is determined by a geocentric radius - vector. Therefore northern drift of the centre of mass in the Earth body [2] as though results in reduction of distances from the satellite up to the sea surface in the southern hemisphere and to their reduction in the northern hemisphere. At averaging of measurements over all ocean surface (mainly located in a southern hemisphere where it occupies about 80 % of the areas) there will be an effect of apparent additional increase of the sea level. Therefore this ("apparent") velocity of increase of the sea level accepts the greater value (about 2.4 mm / year) in comparison with coastal determinations of this velocity that is rather close to the data of satellite observations. The additional effect in increase of the sea level is brought by deformation of the ocean bottom. The both mentioned phenomena: the secular drift of the center of mass of the Earth and the secular expansion of southern hemisphere of the Earth have been predicted by author [2], [3] and have obtained confirmations by space geodesy methods. The offered explanation has the extremely - important value for studying a possible role of thermal and climatic factors which can not apply any more for a big component attributed to it in change of the sea level. The account of fictitious component of this velocity results practically in real value of variation of the average sea level about 1.3-1.6 mm / yr, that completely coordinate positions of researchers of ocean by coastal and altimetry (satellite) methods. Moreover, the given work opens a direct opportunity for an explanation of increase of the sea level as result of deformation of the ocean bottom. This deformation is a major factor of change of the average sea level. Water superseded in a southern hemisphere gives the significant contribution to observably value of velocity of sea level rise up to 0.8-1.2 mm / yr [3, 4]. The work fulfilled at financial support of Russian projects of RFBR: N 07-05-00939 and N 06-02-16665. This abstract (without what or changes) has been accepted to EGU GA 2008 Session IS48 "75th Anniversary of the PSML"(Convener: Woodworth P.) but was not included in its program. References. [1] Nerem R.S., Leuliette E.W., Chambers D.P. (2005) An Integrated Study of Sea Level Change Using Altimetry, Gravity, and In Situ Measurements. Geophys. Res. Abstr., Vol. 7, 09831, Sref-ID: 1607-7962/gra/EGU05-A-09831. [2] Barkin, Yu.V. (1995) About Geocenter Motion Due to Global Changes of Its Dynamical Structure and Tidal Deformations. Vestn. Mosk. Un-ta. Fiz., Astron., Vol. 36, № 5, pp. 99-101 (in Russian). [3] Barkin Yu.V. (2007) Mechanisms of increase of mean sea level and solution of "attribution problem". "Geology of seas and oceans: Materials of XVII International scientific conference (scool) on mariner geology". V. IV. M.: GEOS. 2007. p. 21-23. [4] Barkin Yu.V. (2007) Global increase of mean sea level and erroneous treatment of a role of thermal factors. "Geology of seas and oceans: Materials of XVII International scientific conference (scool) on mariner geology". V. IV. M.: GEOS. 2007. p. 18-20.

  20. Reconstruction of Late Holocene sea-level change in French Polynesia, South Pacific, based on coral reef records

    NASA Astrophysics Data System (ADS)

    Hallmann, Nadine; Camoin, Gilbert; Eisenhauer, Anton; Vella, Claude

    2013-04-01

    Fossil reefs provide valuable sea-level indicators, which help to improve the understanding of past sea-level fluctuations and the prediction of future changes. Recent sea-level changes were reconstructed from emerged reef platforms of two high islands from the Society Islands (Bora Bora, Moorea) and two atolls from the Tuamotu Archipelago (Rangiroa, Tikehau), French Polynesia. These mid-ocean islands can be regarded as tectonically stable for the past few thousand years. Therefore, they are well suited for sea-level studies because they register Holocene eustatic changes, which are not overprinted by tectonic changes. Furthermore, the study sites are located distant from former ice sheets (far field location), which reduces the influence of the glacio-isostatic rebound. Several sea-level indicators, such as in situ coral colonies, including coral microatolls (Porites sp.), bivalves (mainly Tridacna sp.), conglomerates, beachrock, and sediments were analyzed in order to reconstruct Late Holocene relative sea-level changes. Microatolls are discoid corals that develop laterally when upward growth is limited by sea-level. Therefore, they are very accurate recorders of past sea-level. This study provides a detailed sea-level history for French Polynesia using high-precision U/Th (TIMS) dating and GPS measurements with a vertical and horizontal precision of 1-3 cm and a few millimetres, respectively. All samples were analyzed by X-ray diffraction and examined petrographically to exclude diagenetically altered material. The Holocene mean sea level in French Polynesia was thought to have been higher than present (+0.8/+1.0 m) between 5000 and 1250 yr BP, reached a highstand between 2000 and 1500 yr BP and then decreased to the present level (Pirazzoli and Montaggioni, 1988). The highstand has been reported until 1200 yr BP in the Tuamotu Archipelago (Pirazzoli and Montaggioni, 1986). However, sea-level indicators analyzed in this study reveal a highstand of at least 1.5 m above the present sea level. Such high resolution and high precision sea-level data are essential to refine last deglacial sea-level changes and to improve models for the prediction of future global and regional sea-level rise.

  1. Marsh accretion in Oregon estuaries using the marker horizon method and implications of sea level rise

    EPA Science Inventory

    Sea level rise and the ability of marshes to keep up with this rise have been extensively studied on the Atlantic and Gulf coasts of the US; however, there is limited information available for marshes in the Pacific Northwest. Our research focuses on measuring marsh sediment acc...

  2. Sea-Salt Aerosol Forecasts Compared with Wave and Sea-Salt Measurements in the Open Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Kishcha, P.; Starobinets, B.; Bozzano, R.; Pensieri, S.; Canepa, E.; Nickovie, S.; di Sarra, A.; Udisti, R.; Becagli, S.; Alpert, P.

    2012-03-01

    Sea-salt aerosol (SSA) could influence the Earth's climate acting as cloud condensation nuclei. However, there were no regular measurements of SSA in the open sea. At Tel-Aviv University, the DREAM-Salt prediction system has been producing daily forecasts of 3-D distribution of sea-salt aerosol concentrations over the Mediterranean Sea (http://wind.tau.ac.il/saltina/ salt.html). In order to evaluate the model performance in the open sea, daily modeled concentrations were compared directly with SSA measurements taken at the tiny island of Lampedusa, in the Central Mediterranean. In order to further test the robustness of the model, the model performance over the open sea was indirectly verified by comparing modeled SSA concentrations with wave height measurements collected by the ODAS Italia 1 buoy and the Llobregat buoy. Model-vs.-measurement comparisons show that the model is capable of producing realistic SSA concentrations and their day-today variations over the open sea, in accordance with observed wave height and wind speed.

  3. Flooded! An Investigation of Sea-Level Rise in a Changing Climate

    ERIC Educational Resources Information Center

    Gillette, Brandon; Hamilton, Cheri

    2011-01-01

    Explore how melting ice sheets affect global sea levels. Sea-level rise (SLR) is a rise in the water level of the Earth's oceans. There are two major kinds of ice in the polar regions: sea ice and land ice. Land ice contributes to SLR and sea ice does not. This article explores the characteristics of sea ice and land ice and provides some hands-on…

  4. On the level of the cosmic ray sea flux

    SciTech Connect

    Casanova, S.; Aharonian, F. A.; Gabici, S.; Torii, K.; Fukui, Y.; Onishi, T.; Yamamoto, H.; Kawamura, A.

    2009-04-08

    The study of Galactic diffuse {gamma} radiation combined with the knowledge of the distribution of the molecular hydrogen in the Galaxy offers a unique tool to probe the cosmic ray flux in the Galaxy. A methodology to study the level of the cosmic ray 'sea' and to unveil target-accelerator systems in the Galaxy, which makes use of the data from the high resolution survey of the Galactic molecular clouds performed with the NANTEN telescope and of the data from {gamma}-ray instruments, has been developed. Some predictions concerning the level of the cosmic ray 'sea' and the {gamma}-ray emission close to cosmic ray sources for instruments such as Fermi and Cherenkov Telescope Array are presented.

  5. Contribution of small glaciers to global sea level

    USGS Publications Warehouse

    Meier, M.F.

    1984-01-01

    Observed long-term changes in glacier volume and hydrometeorological mass balance models yield data on the transfer of water from glaciers, excluding those in Greenland and Antarctica, to the oceans, The average observed volume change for the period 1900 to 1961 is scaled to a global average by use of the seasonal amplitude of the mass balance. These data are used to calibrate the models to estimate the changing contribution of glaciers to sea level for the period 1884 to 1975. Although the error band is large, these glaciers appear to accountfor a third to half of observed rise in sea level, approximately that fraction not explained by thermal expansion of the ocean.

  6. Milankovitch forcing of the last interglacial sea level.

    PubMed

    Crowley, T J; Kim, K Y

    1994-09-01

    During the last interglacial, sea level was as high as present, 4000 to 6000 years before peak Northern Hemisphere insolation receipt 126,000 years ago. The sea-level results are shown to be consistent with climate models, which simulate a 3 degrees to 4 degrees C July temperature increase from 140,000 to 130,000 years ago in high latitudes, with all Northern Hemisphere land areas being warmer than present by 130,000 years ago. The early warming occurs because obliquity peaked earlier than precession and because precession values were greater than present before peak precessional forcing occurred. These results indicate that a fuller understanding of the Milankovitch-climate connection requires consideration of fields other than just insolation forcing at 65 degrees N. PMID:17801535

  7. Milankovitch forcing of the last interglacial sea level

    SciTech Connect

    Crowley, T.J.; Kim, K.Y.

    1994-09-09

    During the last interglacial, sea level was as high as present, 4000 to 6000 years before peak Northern Hemisphere insolation receipt 126,000 years ago. The sea-level results are shown to be consistent with climate models, which simulate a 3{degrees} to 4{degrees}C July temperature increase from 140,000 to 130,000 years ago in high latitudes, with all Northern Hemisphere land areas being warmer than present by 130,000 years ago. The early warming occurs because obliquity peaked earlier than precession and because precession values were greater than present before peak precessional forcing occurred. These results indicate that a fuller understanding of the Milankovitch-climate connection requires consideration of fields other than just insolation forcing at 65{degrees}N. 16 refs., 4 figs.

  8. Relative sea levels from tide-gauge records

    SciTech Connect

    Emery, K.O.

    1980-12-01

    Mean annual sea levels at 247 tide-gauge stations of the world exhibit a general rise of relative sea level of about 3 mm/year during the past 40 years. In contrast, general uplift of the land is typical of high northern latitudes, where unloading of the crust by melt of Pleistocene ice sheets is significant. Erratic movements are typical of belts having crustal overthrusting and active volcanism. Short-term (5- and 10-year) records reveal recent changes in rates, but such short time spans may be so influenced by climatic cycles that identification of new trends is difficult, especially with the existing poor distribution and reporting of tide-gauge data.

  9. Effects of sea level rise on rugged coasts

    SciTech Connect

    Belknap, D.F. )

    1990-05-01

    Rugged coasts are usually rock framed, with more or less discontinuous unconsolidated sediment supply. Evolution of rugged coasts with respect to rising sea level is locally variable, involving rapid changes in facies over short distances and times. Glaciated and tectonic coasts are common examples. Three aspects of coastal evolution dominate rugged coasts during rising sea level: (1) drowning of resistant rocky shores, (2) bluff erosion in sediments or cliff erosion in less resistant rocks, involving marine abrasion as well as terrestrial processes and control by rock structures, and (3) larger scale structural control creating indentations and salients. The third aspect results in embayed coasts that may evolve as estuarine, fjord, or barrier-backbarrier systems. Of overriding concern for stratigraphic interpretation are paleogeography and sediment sources. The Maine coast and nearshore are classic examples of drowned shoreline, and record the effects of glaciation and rapid relative sea level changes over the past 14,000 yr. Offshore at {minus}60 m is a lowstand shoreline (approximately 10,000 yr B.P.), which ranges from cliff to barrier split( ). The inner shelf has evolved through drowning of shelf valleys and peninsulas, bluff erosion and formation of local transgressive barrier-backbarrier systems. Often short-term steady state equilibrium is established until a threshold is reached followed by rapid reorganization at a new location. This occurs in barrier systems, by overtopping of sills in estuaries, and in variable bluff and cliff erosion sites. Preservation potential is high only in valley axes and at sea level stillstand positions.

  10. Global warming, sea-level rise, and coastal marsh survival

    USGS Publications Warehouse

    Cahoon, Donald R.

    1997-01-01

    Coastal wetlands are among the most productive ecosystems in the world. These wetlands at the land-ocean margin provide many direct benefits to humans, including habitat for commercially important fisheries and wildlife; storm protection; improved water quality through sediment, nutrient, and pollution removal; recreation; and aesthetic values. These valuable ecosystems will be highly vulnerable to the effects of the rapid rise in sea level predicted to occur during the next century as a result of global warming.

  11. Global ice-sheet system interlocked by sea level

    SciTech Connect

    Denton, G.H.; Hughes, T.J.; Karlen, W.

    1986-01-01

    Denton and Hughes postulated that sea level linked a global ice-sheet system with both terrestrial and grounded marine components during later Quaternary ice ages. Summer temperature changes near Northern Hemisphere melting margins initiated sea-level fluctuations that controlled marine components in both polar hemispheres. It was further proposed that variations of this ice-sheet system amplified and transmitted Milankovitch summer half-year insolation changes between 45 and 75/sup 0/N into global climatic changes. New tests of this hypothesis implicate sea level as a major control of the areal extent of grounded portions of the Antarctic Ice Sheet. But factors other than areal changes of the grounded Antarctic Ice Sheet may have strongly influenced Southern Hemisphere climate and terminated the last ice age simultaneously in both polar hemispheres. Atmospheric carbon dioxide linked to high-latitude oceans is the most likely candidate, but another potential influence was high-frequency climatic oscillations. It is postulated that variations in atmospheric carbon dioxide acted through an Antarctic ice shelf linked to the grounded ice sheet to produce and terminate Southern Hemisphere ice-age climate. It is further postulated that Milankovitch summer insolation combined with a warm-high frequency oscillation caused marked recession of Northern Hemisphere ice-sheet melting margins and the North Atlantic polar front about 14,000 /sup 14/C yr B.P. This permitted renewed formation of North Atlantic Deep Water, which could well have controlled atmospheric carbon dioxide. Combined melting and consequent sea-level rise from the three warming factors initiated irreversible collapse of the interlocked global ice-sheet system, which was at its largest but most vulnerable configuration.

  12. Investigaton of Sea Level Change Along the Black Sea Coast from Tide Gauge and Satellite Altimetry

    NASA Astrophysics Data System (ADS)

    Avsar, N. B.; Kutoglu, S. H.; Jin, S.; Erol, B.

    2015-12-01

    In this study, we focus on sea level changes along the Black Sea coast. For this purpose, at same observation period the linear trends and the components of seasonal variations of sea level change are estimated at 12 tide gauge sites (Amasra, Igneada, Trabzon-II, Sinop, Sile, Poti, Batumi, Sevastopol, Tuapse, Varna, Bourgas, and Constantza) located along the Black Sea coast and available altimetric grid points closest to the tide gauge locations. The consistency of the results derived from both observations are investigated and interpreted. Furthermore, in order to compare the trends at the same location, it is interpolated from the trends obtained at the altimetric grid points in the defined neighbouring area with a diameter of 0.125° using a weighted average interpolation algorithm at each tide gauge site. For some tide gauges such as Sevastopol, Varna, and Bourgas, it is very likely that the trend estimates are not reliable because the time-spans overlapping the altimeter period are too short. At Sile, the long-term change for the time series of both data types do not give statistically significant linear rates. However, when the sites have long-term records, a general agreement between the satellite altimetry and tide gauge time series is observed at Poti (~20 years) and Tuapse (~18 years). On the other hand, the difference of annual phase between satellite altimetry and tide gauge results is from 1.32° to 71.48°.

  13. Nest inundation from sea-level rise threatens sea turtle population viability

    PubMed Central

    Pike, David A.; Roznik, Elizabeth A.; Bell, Ian

    2015-01-01

    Contemporary sea-level rise will inundate coastal habitats with seawater more frequently, disrupting the life cycles of terrestrial fauna well before permanent habitat loss occurs. Sea turtles are reliant on low-lying coastal habitats worldwide for nesting, where eggs buried in the sand remain vulnerable to inundation until hatching. We show that saltwater inundation directly lowers the viability of green turtle eggs (Chelonia mydas) collected from the world's largest green turtle nesting rookery at Raine Island, Australia, which is undergoing enigmatic decline. Inundation for 1 or 3 h reduced egg viability by less than 10%, whereas inundation for 6 h reduced viability by approximately 30%. All embryonic developmental stages were vulnerable to mortality from saltwater inundation. Although the hatchlings that emerged from inundated eggs displayed normal physical and behavioural traits, hypoxia during incubation could influence other aspects of the physiology or behaviour of developing embryos, such as learning or spatial orientation. Saltwater inundation can directly lower hatching success, but it does not completely explain the consistently low rates of hatchling production observed on Raine Island. More frequent nest inundation associated with sea-level rise will increase variability in sea turtle hatching success spatially and temporally, due to direct and indirect impacts of saltwater inundation on developing embryos. PMID:26587269

  14. Nest inundation from sea-level rise threatens sea turtle population viability.

    PubMed

    Pike, David A; Roznik, Elizabeth A; Bell, Ian

    2015-07-01

    Contemporary sea-level rise will inundate coastal habitats with seawater more frequently, disrupting the life cycles of terrestrial fauna well before permanent habitat loss occurs. Sea turtles are reliant on low-lying coastal habitats worldwide for nesting, where eggs buried in the sand remain vulnerable to inundation until hatching. We show that saltwater inundation directly lowers the viability of green turtle eggs (Chelonia mydas) collected from the world's largest green turtle nesting rookery at Raine Island, Australia, which is undergoing enigmatic decline. Inundation for 1 or 3 h reduced egg viability by less than 10%, whereas inundation for 6 h reduced viability by approximately 30%. All embryonic developmental stages were vulnerable to mortality from saltwater inundation. Although the hatchlings that emerged from inundated eggs displayed normal physical and behavioural traits, hypoxia during incubation could influence other aspects of the physiology or behaviour of developing embryos, such as learning or spatial orientation. Saltwater inundation can directly lower hatching success, but it does not completely explain the consistently low rates of hatchling production observed on Raine Island. More frequent nest inundation associated with sea-level rise will increase variability in sea turtle hatching success spatially and temporally, due to direct and indirect impacts of saltwater inundation on developing embryos. PMID:26587269

  15. Estimating decadal variability in sea level from tide gauge records: An application to the North Sea

    NASA Astrophysics Data System (ADS)

    Frederikse, Thomas; Riva, Riccardo; Slobbe, Cornelis; Broerse, Taco; Verlaan, Martin

    2016-03-01

    One of the primary observational data sets of sea level is represented by the tide gauge record. We propose a new method to estimate variability on decadal time scales from tide gauge data by using a state space formulation, which couples the direct observations to a predefined state space model by using a Kalman filter. The model consists of a time-varying trend and seasonal cycle, and variability induced by several physical processes, such as wind, atmospheric pressure changes and teleconnection patterns. This model has two advantages over the classical least-squares method that uses regression to explain variations due to known processes: a seasonal cycle with time-varying phase and amplitude can be estimated, and the trend is allowed to vary over time. This time-varying trend consists of a secular trend and low-frequency variability that is not explained by any other term in the model. As a test case, we have used tide gauge data from stations around the North Sea over the period 1980-2013. We compare a model that only estimates a trend with two models that also remove intra-annual variability: one by means of time series of wind stress and sea level pressure, and one by using a two-dimensional hydrodynamic model. The last two models explain a large part of the variability, which significantly improves the accuracy of the estimated time-varying trend. The best results are obtained with the hydrodynamic model. We find a consistent low-frequency sea level signal in the North Sea, which can be linked to a steric signal over the northeastern part of the Atlantic.

  16. Precessional and Sea Level Induced Hydrological Changes in the Mediterranean Sea During the Messinian Salinity Crisis

    NASA Astrophysics Data System (ADS)

    Murphy, L. N.; Kirk-Davidoff, D.; Mahowald, N.; Otto-Bliesner, B.

    2007-12-01

    The Messinian Salinity Crisis (MSC) occurred nearly 6 million years ago when tectonic uplift closed the straits connecting the Mediterranean Sea (MS) with the Atlantic Ocean. High rates of evaporation and diminishing water input led to a 1500-2500 m drop in MS level and the deposition of a thick layer of evaporites (Hsu et al, 1973). Cyclic patterns in evaporite deposition during the MSC have been correlated with variations in precession. It is important to model both sea level induced climatic changes and precessional changes to see how they feedback on the hydrological cycle and therefore the desiccation process during this remarkable event. In this study, experiments were conducted using the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM 3.1) configured with a Slab Ocean Model (SOM). We attempted to break down the series of events that occurred during the MSC to isolate the effect of each separate component on the atmosphere. In all experiments the horizontal ocean heat transport is turned off to represent the isolation of the MS from the Atlantic Ocean. The first experiment simulated the beginning of the MSC when a substantial sea level lowering occurred and extremely dry conditions led to deposition of the "Lower Evaporite" layer. In this experiment the level of the MS is reduced by 1500 m and water is removed from the basin. Lowering the sea level of the MS results in anomalous cooling of more than 2 K in the North Pacific. This agrees with proxy data that indicates extensive glaciation just after the initiation of the MSC. Another experiment simulated the end of the MSC during the Lago-Mare event when water is believed to have existed at the bottom of the desiccated sea. In our Lago-Mare experiment, the sea level is reduced up to 1500 m but water remains in the basin. Our Lago-Mare simulation results in anomalous wintertime warming of more than 10 K over the MS. Anomalous heating drives local changes in the wind field that leads to convergence at the northern margin of the basin. This yields a topographically induced precipitation anomaly of more than 1500 mm yr-1 over the Alps when water remains at the bottom of the basin. This result supports geological evidence of wetter conditions in the peripheral mountains that are believed to have led to more humid conditions during the Lago-Mare event. New results simulating the influence of the precessional cycle on the climate of the desiccated basin in both scenarios will be presented. Precessional variations, which influence the hydrological cycle, may play a key role in the desiccation process.

  17. Sea level, paleogeography, and archeology on California's Northern Channel Islands

    USGS Publications Warehouse

    Reeder-Myers, Leslie; Erlandson, Jon M.; Muhs, Daniel R.; Rick, Torben C.

    2015-01-01

    Sea-level rise during the late Pleistocene and early Holocene inundated nearshore areas in many parts of the world, producing drastic changes in local ecosystems and obscuring significant portions of the archeological record. Although global forces are at play, the effects of sea-level rise are highly localized due to variability in glacial isostatic adjustment (GIA) effects. Interpretations of coastal paleoecology and archeology require reliable estimates of ancient shorelines that account for GIA effects. Here we build on previous models for California's Northern Channel Islands, producing more accurate late Pleistocene and Holocene paleogeographic reconstructions adjusted for regional GIA variability. This region has contributed significantly to our understanding of early New World coastal foragers. Sea level that was about 80–85 m lower than present at the time of the first known human occupation brought about a landscape and ecology substantially different than today. During the late Pleistocene, large tracts of coastal lowlands were exposed, while a colder, wetter climate and fluctuating marine conditions interacted with rapidly evolving littoral environments. At the close of the Pleistocene and start of the Holocene, people in coastal California faced shrinking land, intertidal, and subtidal zones, with important implications for resource availability and distribution.

  18. Hydrothermal iron flux variability following rapid sea level changes

    NASA Astrophysics Data System (ADS)

    Middleton, Jennifer L.; Langmuir, Charles H.; Mukhopadhyay, Sujoy; McManus, Jerry F.; Mitrovica, Jerry X.

    2016-04-01

    Sea level changes associated with Pleistocene glacial cycles have been hypothesized to modulate melt production and hydrothermal activity at ocean ridges, yet little is known about fluctuations in hydrothermal circulation on time scales longer than a few millennia. We present a high-resolution record of hydrothermal activity over the past 50 ka using elemental flux data from a new sediment core from the Mir zone of the TAG hydrothermal field at 26°N on the Mid-Atlantic Ridge. Mir sediments reveal sixfold to eightfold increases in hydrothermal iron and copper deposition during the Last Glacial Maximum, followed by a rapid decline during the sea level rise associated with deglaciation. Our results, along with previous observations from Pacific and Atlantic spreading centers, indicate that rapid sea level changes influence hydrothermal output on mid-ocean ridges. Thus, climate variability may discretize volcanic processing of the solid Earth on millennial time scales and subsequently stimulate variability in biogeochemical interactions with volcanic systems.

  19. The Paleozoic world: Continental flooding, hypsometry, and sea level

    SciTech Connect

    Algeo, T.J. . Dept. of Geology); Seslavinsky, K.B. ); Wilkinson, B.H. . Dept. of Geological Sciences)

    1992-01-01

    Absolute amplitudes of Paleozoic sea-level fluctuations are poorly known: two major curves show eustatic maxima of +300 m (Vail et al. 1977) and +600 m (Hallam 1984). Based on analysis of the flooding records of thirteen Paleozoic landmasses, the authors estimate that sea-level elevations were substantially lower than previously thought, ca. 50--220 m for most of the Paleozoic. The analysis also shows that: (1) small continents are inherently more floodable than large continents, (2) there is no difference in mean flooding of continents of a given size between the Early and Late Paleozoic, and (3) reduced global flooding during the Late Paleozoic is primarily attributable to the existence of a few large continents, rather than many small ones as during the Early Paleozoic. Global sea-level trends reflect the division of the Paleozoic into two geotectonic subcycles comprising the Cambro-Silurian (terminated by the Taconic/Caledonian Orogeny). Deviations of individual continents from the mean global curve are due to changes in hypsometry associated with tectonic/epeirogenic events. For example, a major Early Silurian regression on Laurentia resulted from the Taconic Orogeny, while large Early Ordovician and Middle-Late Devonian regressions on Gondwana are associated with rifting of the North China and South China/Indochina blocks.

  20. Objective sea level pressure analysis for sparse data areas

    NASA Technical Reports Server (NTRS)

    Druyan, L. M.

    1972-01-01

    A computer procedure was used to analyze the pressure distribution over the North Pacific Ocean for eleven synoptic times in February, 1967. Independent knowledge of the central pressures of lows is shown to reduce the analysis errors for very sparse data coverage. The application of planned remote sensing of sea-level wind speeds is shown to make a significant contribution to the quality of the analysis especially in the high gradient mid-latitudes and for sparse coverage of conventional observations (such as over Southern Hemisphere oceans). Uniform distribution of the available observations of sea-level pressure and wind velocity yields results far superior to those derived from a random distribution. A generalization of the results indicates that the average lower limit for analysis errors is between 2 and 2.5 mb based on the perfect specification of the magnitude of the sea-level pressure gradient from a known verification analysis. A less than perfect specification will derive from wind-pressure relationships applied to satellite observed wind speeds.

  1. A Mid-Holocene sea level fluctuation in South Carolina

    SciTech Connect

    Gayes, P.T.; Nelson, D.D. . Marine and Wetland Studies); Scott, D.B.; Collins, E. . Centre for Marine Geology)

    1993-03-01

    A high stand of relative sea level occurred at 4.2 ka in Murrells Inlet on the northern coast of South Carolina. The event was identified using benthic foraminiferal zonations, marsh stratigraphic relations and radiocarbon data. This highstand reached a maximum of approximately [minus]1 meter MSD and was followed by a fall of 2 meters until 3.6 ka. Subsequent to 3.6 ka submergence was slow averaging 10 cm/century to the present. A second smaller fluctuation may have occurred around 2.5 ka but remains poorly constrained. Although a Mid-Holocene highstand had been suggested by others, it has not been well constrained. New data from North Inlet, South Carolina also record a baselevel change in the Mid-Holocene. Strong differential submergence between Murrells Inlet and Santee Delta, South Carolina, has occurred over the last 4 ka, probably as a result of sediment loading by and subsidence of, the Santee Delta. The occurrence of the 4.2 ka highstand corresponds in the range (7 [minus] 4 ka) to that of the Holocene Hypsithermal. The rate and magnitude of the relative sea level fluctuation are similar to those projected for future flooding and suggest that the evaluation of the Hypsithermal highstand may provide an insight to continued sea-level rise.

  2. Relative sea level changes during the Cretaceous in Israel

    SciTech Connect

    Flexer, A.; Rosenfeld, A.; Lipson-Benitah, S.; Honigstein, A.

    1986-11-01

    Detailed lithologic, microfaunal, and biometric investigations, using relative abundances, diversity indexes, and duration charts of ostracods and foraminifera, allowed the recognition of sea level changes during the Cretaceous of Israel. Three major transgressive-regressive sedimentation cycles occur on the northwest margins of the Arabian craton. These cycles are the Neocomian-Aptian, which is mostly terrigenous sediments; the Albian-Turonian, which is basin marls and platform carbonates; and the Senonian, which is uniform marly chalks. The cycles are separated by two major regional unconformities, the Aptian-Albian and Turonian-Coniacian boundaries. The sedimentary cycles are related to regional tectonic and volcanic events and eustatic changes. The paleodepth curve illustrates the gradual sea level rise, reaching its maximum during the Late Cretaceous, with conspicuous advances during the late Aptian, late Albian-Cenomanian, early Turonian, early Santonian, and early Campanian. Major lowstands occur at the Aptian-Albian, Cenomanian-Turonian, Turonian-Coniacian, and Campanian-Maastrichtian boundaries. This model for Israel agrees well with other regional and global sea level fluctuations. Four anoxic events (black shales) accompanying transgressions correspond to the Cretaceous oceanic record. They hypothesize the presence of mature oil shales in the present-day eastern Mediterranean basin close to allochthonous reef blocks detached from the Cretaceous platform. 11 figures.

  3. Sea level, paleogeography, and archeology on California's Northern Channel Islands

    NASA Astrophysics Data System (ADS)

    Reeder-Myers, Leslie; Erlandson, Jon M.; Muhs, Daniel R.; Rick, Torben C.

    2015-03-01

    Sea-level rise during the late Pleistocene and early Holocene inundated nearshore areas in many parts of the world, producing drastic changes in local ecosystems and obscuring significant portions of the archeological record. Although global forces are at play, the effects of sea-level rise are highly localized due to variability in glacial isostatic adjustment (GIA) effects. Interpretations of coastal paleoecology and archeology require reliable estimates of ancient shorelines that account for GIA effects. Here we build on previous models for California's Northern Channel Islands, producing more accurate late Pleistocene and Holocene paleogeographic reconstructions adjusted for regional GIA variability. This region has contributed significantly to our understanding of early New World coastal foragers. Sea level that was about 80-85 m lower than present at the time of the first known human occupation brought about a landscape and ecology substantially different than today. During the late Pleistocene, large tracts of coastal lowlands were exposed, while a colder, wetter climate and fluctuating marine conditions interacted with rapidly evolving littoral environments. At the close of the Pleistocene and start of the Holocene, people in coastal California faced shrinking land, intertidal, and subtidal zones, with important implications for resource availability and distribution.

  4. How mangrove forests adjust to rising sea level

    USGS Publications Warehouse

    Krauss, Ken W.; McKee, Karen L.; Lovelock, Catherine E.; Cahoon, Donald R.; Saintilan, Neil; Reef, Ruth; Chen, Luzhen

    2014-01-01

    Mangroves are among the most well described and widely studied wetland communities in the world. The greatest threats to mangrove persistence are deforestation and other anthropogenic disturbances that can compromise habitat stability and resilience to sea-level rise. To persist, mangrove ecosystems must adjust to rising sea level by building vertically or become submerged. Mangroves may directly or indirectly influence soil accretion processes through the production and accumulation of organic matter, as well as the trapping and retention of mineral sediment. In this review, we provide a general overview of research on mangrove elevation dynamics, emphasizing the role of the vegetation in maintaining soil surface elevations (i.e. position of the soil surface in the vertical plane). We summarize the primary ways in which mangroves may influence sediment accretion and vertical land development, for example, through root contributions to soil volume and upward expansion of the soil surface. We also examine how hydrological, geomorphological and climatic processes may interact with plant processes to influence mangrove capacity to keep pace with rising sea level. We draw on a variety of studies to describe the important, and often under-appreciated, role that plants play in shaping the trajectory of an ecosystem undergoing change.

  5. Sea level rise in Louisiana and Gulf of Mexico

    SciTech Connect

    Ramsey, K.; Penland, S. )

    1989-09-01

    Data from two tide-gage networks in Louisiana and the northern Gulf of Mexico were analyzed to determine local and regional trends in relative sea level rise. The US Army Corps of Engineers (USACE) maintains a network of 83 tide-gage stations throughout coastal Louisiana. Of these, 20 have records for two lunar nodal cycles or more, and some date back to 1933. The authors used the USACE data set to determine the local and regional character of relative sea level rise in Louisiana. The National ocean Survey (NOS) maintains nine tide gage stations throughout the northern Gulf of Mexico in Texas, Louisiana, Mississippi, Alabama, and Florida. All of the records of these stations exceed two lunar nodal cycles, and some date back to 1908. The authors used the NOS data set to determine the character of relative sea level rise throughout the northern Gulf of Mexico. This investigation updates and extends the previous systematic regional tide gage analysis (which covered 1908-1983) to 1988.

  6. Glacier calving, dynamics, and sea-level rise. Final report

    SciTech Connect

    Meier, M.F.; Pfeffer, W.T.; Amadei, B.

    1998-08-01

    The present-day calving flux from Greenland and Antarctica is poorly known, and this accounts for a significant portion of the uncertainty in the current mass balance of these ice sheets. Similarly, the lack of knowledge about the role of calving in glacier dynamics constitutes a major uncertainty in predicting the response of glaciers and ice sheets to changes in climate and thus sea level. Another fundamental problem has to do with incomplete knowledge of glacier areas and volumes, needed for analyses of sea-level change due to changing climate. The authors proposed to develop an improved ability to predict the future contributions of glaciers to sea level by combining work from four research areas: remote sensing observations of calving activity and iceberg flux, numerical modeling of glacier dynamics, theoretical analysis of the calving process, and numerical techniques for modeling flow with large deformations and fracture. These four areas have never been combined into a single research effort on this subject; in particular, calving dynamics have never before been included explicitly in a model of glacier dynamics. A crucial issue that they proposed to address was the general question of how calving dynamics and glacier flow dynamics interact.

  7. Tidal marsh susceptibility to sea-level rise: importance of local-scale models

    USGS Publications Warehouse

    Thorne, Karen M.; Buffington, Kevin J.; Elliott-Fisk, Deborah L.; Takekawa, John

    2015-01-01

    Increasing concern over sea-level rise impacts to coastal tidal marsh ecosystems has led to modeling efforts to anticipate outcomes for resource management decision making. Few studies on the Pacific coast of North America have modeled sea-level rise marsh susceptibility at a scale relevant to local wildlife populations and plant communities. Here, we use a novel approach in developing an empirical sea-level rise ecological response model that can be applied to key management questions. Calculated elevation change over 13 y for a 324-ha portion of San Pablo Bay National Wildlife Refuge, California, USA, was used to represent local accretion and subsidence processes. Next, we coupled detailed plant community and elevation surveys with measured rates of inundation frequency to model marsh state changes to 2100. By grouping plant communities into low, mid, and high marsh habitats, we were able to assess wildlife species vulnerability and to better understand outcomes for habitat resiliency. Starting study-site conditions were comprised of 78% (253-ha) high marsh, 7% (30-ha) mid marsh, and 4% (18-ha) low marsh habitats, dominated by pickleweed Sarcocornia pacifica and cordgrass Spartina spp. Only under the low sea-level rise scenario (44 cm by 2100) did our models show persistence of some marsh habitats to 2100, with the area dominated by low marsh habitats. Under mid (93 cm by 2100) and high sea-level rise scenarios (166 cm by 2100), most mid and high marsh habitat was lost by 2070, with only 15% (65 ha) remaining, and a complete loss of these habitats by 2080. Low marsh habitat increased temporarily under all three sea-level rise scenarios, with the peak (286 ha) in 2070, adding habitat for the endemic endangered California Ridgway’s rail Rallus obsoletus obsoletus. Under mid and high sea-level rise scenarios, an almost complete conversion to mudflat occurred, with most of the area below mean sea level. Our modeling assumed no marsh migration upslope due to human levee and infrastructure preventing these types of processes. Other modeling efforts done for this area have projected marsh persistence to 2100, but our modeling effort with site-specific datasets allowed us to model at a finer resolution with much higher local confidence, resulting in different results for management. Our results suggest that projected sea-level rise will have significant impacts on marsh plant communities and obligate wildlife, including those already under federal and state protection. Comprehensive modeling as done here improves the potential to implement adaptive management strategies and prevent marsh habitat and wildlife loss in the future.

  8. GPS and Tide Gauge Constraints on Subsidence and Relative sea Level Rise Along the US East Coast

    NASA Astrophysics Data System (ADS)

    Jiang, Y.; Wdowinski, S.; Dixon, T. H.; Harrison, C. G.

    2007-12-01

    Relative sea level change has two distinct components, absolute sea level variation and movement of Earth's crust. The movement of the crust can sometimes bias estimation of absolute sea level change as inferred by tide gauge data. We employ high accuracy GPS measurements (Sella et al., 2007) to detect movement of the crust in eastern North America, primarily reflecting areas that are affected by Glacial Isostatic Adjustment (GIA). In particular, these data define the collapse of the "peripheral bulge". We compare the GPS data to relative sea level change as recorded by tide gauges. We use all tide gauge stations along the east coast of North America that have more than 60 years of data, and estimate the rate of relative sea level rise using a model that accounts for annual, semi-annual and decadal signals in the time series. The GPS data show regions with subsidence rate > 2mm/year between Virginia and South Carolina, ~1900--2500km away from the uplift center in Hudson Bay. Tide gauge data in these areas show about 4mm/year relative sea level rise. The inferred global sea level rise rate is about 2mm/year. Thus, land subsidence in these regions effectively doubles the relative sea level rise rate and the corresponding natural hazard.

  9. Historical sea level data rescue to assess long-term sea level evolution: Saint-Nazaire observatory (Loire estuary, France) since 1863.

    NASA Astrophysics Data System (ADS)

    Ferret, Yann; Voineson, Guillaume; Pouvreau, Nicolas

    2014-05-01

    Nowadays, the study of the global sea level rise is a strong societal concern. The analysis of historical records of water level proves to be an ideal way to provide relevant arguments regarding the observed trends. In France, many systematic sea level observations have taken place since the mid-1800s. Despite this rich history, long sea level data sets digitally available are still scarce. Currently, only the time series of Brest, Marseille and recently the composite one of the Pertuis d'Antioche span periods longer than a century and are available to be taken into account in studies dealing with long term sea-level evolution. In this context, an important work of "data archaeology" is undertaken to rescue the numerous existing analog historical data that is part of the French scientific and cultural heritage. The present study is focused on the measurements carried out at the sea level observatory of Saint-Nazaire, located on the French Atlantic coast in the Loire estuary mouth area. Measurements were automatically performed with the use of float tide gauges from 1863 to 2007, but include some important gaps between 1920 and 1950. Since 2007, the Saint-Nazaire observatory is part of the French RONIM network operated by SHOM, and the old mechanical tide gauge has been superseded by a radar tide gauge (operated by "Grand Port Maritime" of Nantes-Saint-Nazaire). In total, the covered period is up to 150-year-long, including at least 125 years of continuous sea level measurements. With the reconstruction of this new data set, we aim at improving our knowledge on trends in sea level components on the Atlantic coast on large scale and on the coast vulnerability at more local scale. Moreover, because of the location of the station, it should be possible as well to study the influence of the Loire River on water level since the 19th century. It has been shown that the tidal range was strongly modified during the last century because of the anthropogenic influence along the river (dredging, coastal structures, etc.). This is particularly remarkable in upstream areas such as Nantes, but the impact in downstream locations such as Saint-Nazaire is still not completely quantified. As a first and primordial step, this study implies the inventory and the digitalization of existing ledgers and tidal charts. This time-demanding work induces to check the data quality and to make these data consistent over time in terms of vertical reference and time systems, which both evolved during the studied period. Preliminary analyses assess the high quality of the measurements. Once the final time-serie has been checked and rendered coherent, it will be made available in existing national databanks and websites: REFMAR for high-frequency data (hourly) and SONEL for the corresponding mean sea levels (daily, monthly and yearly).

  10. Wireless Fluid Level Measuring System

    NASA Technical Reports Server (NTRS)

    Taylor, Bryant D. (Inventor); Woodard, Stanley E. (Inventor)

    2007-01-01

    A level-sensing probe positioned in a tank is divided into sections with each section including (i) a fluid-level capacitive sensor disposed along the length thereof, (ii) an inductor electrically coupled to the capacitive sensor, (iii) a sensor antenna positioned for inductive coupling to the inductor, and (iv) an electrical conductor coupled to the sensor antenna. An electrically non-conductive housing accessible from a position outside of the tank houses antennas arrayed in a pattern. Each antenna is electrically coupled to the electrical conductor from a corresponding one of the sections. A magnetic field response recorder has a measurement head with transceiving antennas arrayed therein to correspond to the pattern of the housing's antennas. When a measurement is to be taken, the measurement head is mechanically coupled to the housing so that each housing antenna is substantially aligned with a specific one of the transceiving antennas.

  11. Risk of Sea Level Rise from Antarctic Ice Sheet Instability

    NASA Astrophysics Data System (ADS)

    Edwards, T.; Ritz, C.; Durand, G.; Payne, A. J.; Peyaud, V.; Hindmarsh, R. C. A.

    2014-12-01

    Large parts of the Antarctic ice sheet lie below sea level and may be vulnerable to Marine Ice Sheet Instability (MISI), a positive feedback in which ice shelf collapse or exposure to warmer water triggers self-sustaining ice loss. But uncertainty quantification with perturbed parameter ensembles - for probabilistic projections of the risk of sea level rise under MISI - is currently precluded for models that can explicitly simulate migration of the grounding line (that divides ice resting on bedrock from floating ice shelves), due to their computational expense. We present a new approach implemented in the ice sheet model GRISLI that does not require high resolution and therefore allows uncertainty quantification: we parameterise grounding line retreat rate as a function of an effective basal drag coefficient. We vary the parameters of this scheme along with 13 other inputs (basal drag law exponent, instability onset by sector, and bedrock topography) to generate a 3000 member ensemble. We calibrate the ensemble in a Bayesian statistical framework using observations of present day mass loss in the Amundsen Sea, where the grounding line is currently retreating. We obtain calibrated numerical model projections of the probability of sea level rise over the next 200 years in the event of Antarctic ice sheet instability. We find the projections are sensitive to model inputs, such as the basal drag law exponent. Nevertheless, our assessment is consistent with the lower end of previous estimates, indicating that the highest of "upper end" estimates are unlikely. This result is due to both ice dynamical theory, which constrains the regions over which MISI can occur and the maximum tensile stresses at the grounding line, and calibration, which constrains the maximum grounding line retreat rate and the values of effective basal drag coefficient over which this can occur. Our results highlight the importance of formal quantification of the effect of model uncertainties, and of constraining projections to plausible values using ice dynamical theory and observational calibration.

  12. Bayesian Statistical Analysis of Historical and Late Holocene Rates of Sea-Level Change

    NASA Astrophysics Data System (ADS)

    Cahill, Niamh; Parnell, Andrew; Kemp, Andrew; Horton, Benjamin

    2014-05-01

    A fundamental concern associated with climate change is the rate at which sea levels are rising. Studies of past sea level (particularly beyond the instrumental data range) allow modern sea-level rise to be placed in a more complete context. Considering this, we perform a Bayesian statistical analysis on historical and late Holocene rates of sea-level change. The data that form the input to the statistical model are tide-gauge measurements and proxy reconstructions from cores of coastal sediment. The aims are to estimate rates of sea-level rise, to determine when modern rates of sea-level rise began and to observe how these rates have been changing over time. Many of the current methods for doing this use simple linear regression to estimate rates. This is often inappropriate as it is too rigid and it can ignore uncertainties that arise as part of the data collection exercise. This can lead to over confidence in the sea-level trends being characterized. The proposed Bayesian model places a Gaussian process prior on the rate process (i.e. the process that determines how rates of sea-level are changing over time). The likelihood of the observed data is the integral of this process. When dealing with proxy reconstructions, this is set in an errors-in-variables framework so as to take account of age uncertainty. It is also necessary, in this case, for the model to account for glacio-isostatic adjustment, which introduces a covariance between individual age and sea-level observations. This method provides a flexible fit and it allows for the direct estimation of the rate process with full consideration of all sources of uncertainty. Analysis of tide-gauge datasets and proxy reconstructions in this way means that changing rates of sea level can be estimated more comprehensively and accurately than previously possible. The model captures the continuous and dynamic evolution of sea-level change and results show that not only are modern sea levels rising but that the rates of rise are continuously increasing. Analysis of the a global tide-gauge record (Church and White, 2011) indicated that the rate of sea-level rise increased continuously since 1880AD and is currently 2.57mm/yr (95% credible interval of 1.71 to 4.35mm/yr). Application of the model a proxy reconstruction from North Carolina (Kemp et al., 2011) indicated that the mean rate of rise in this locality since the middle of the 19th century (current rate of 2.66 mm/yr with a 95% credible interval of 1.29 to 4.59mm/yr) is in agreement with results from the tide gauge analysis and is unprecedented in at least the last 2000 years.

  13. Assessment on the Vulnerability of Mangrove Ecosystems in the Guangxi Coastal Zone under Sea Level Rise

    NASA Astrophysics Data System (ADS)

    Li, S.; Ge, Z.; Zhang, L.

    2013-12-01

    Sea level rise caused by global climate change will have significant impacts on coastal zone. The mangrove ecosystems occur at the intertidal zone in tropical and subtropical coasts and are particularly sensitive to sea level rise. To study the responses of mangrove ecosystems to sea level rise, assess the impacts of sea level rise on mangrove ecosystem and formulate the feasible and practical mitigation strategies are the important prerequisites for securing the coastal ecosystems. In this research, taking the mangrove ecosystems in the coastal zone of Guangxi province, China as a case study, the potential impacts of sea level rise on the mangrove ecosystems were analyzed by adopting the SPRC (Source-Pathway- Receptor- Consequence) model. An index system for vulnerability assessment on coastal mangrove ecosystems under sea level rise was worked out, in which rate of sea level rise, subsidence/uplift rate, habitat elevation, daily inundation duration, intertidal slope and sedimentation rate were selected as the key indicators according to the IPCC definition of vulnerability, i.e. the aspects of exposure, sensitivity and adaptation. A quantitatively spatial assessment method based on the GIS platform was established by quantifying each indicator, calculating the vulnerability index and grading the vulnerability. The vulnerability assessment based on the sea-level rise rates of the present trend and IPCC A1F1 scenario were performed for three sets of projections of short-term (2030s), mid-term (2050s) and long-term (2100s). The results showed at the present trend of sea level rise rate of 0.27 cm/a, the mangrove ecosystems in the coastal zone of Guangxi was within the EVI score of 0 in the projections of 2030s, 2050s and 2100s, respectively. As the sedimentation and land uplift could offset the rate of sea level rise and the impact of sea level rise on habitats/species of mangrove ecosystems was negligible. While at the A1F1 scenario with a sea level rise rate of 0.59 cm/a, 5.4 % of mangrove ecosystems was within the EVI score of 1 (low vulnerability) in 2030s. The percentage of low vulnerability of mangrove ecosystems increased to 18.7% in 2050s and 27.8% in 2100s at the A1F1 scenario. The spatiotemporal occurrences of low vulnerability were mainly distributed in the coast of Beihai and Maoweihai. The SPRC model adopted, the methodology of vulnerability assessment developed and the results presented in this study could objectively and quantitatively assess the vulnerability of mangrove ecosystems in Guangxi under the impacts of sea level rise. Based on the results from this study, some mitigation measures should be considered in the future for securing the coastal mangrove ecosystems, which include management of sedimentation, rehabilitating and recreating mangrove habitat, and controlling reclamation.

  14. Effects of sea maturity on satellite altimeter measurements

    NASA Technical Reports Server (NTRS)

    Glazman, Roman E.; Pilorz, Stuart H.

    1990-01-01

    For equilibrium and near-equilibrium sea states, the wave slope variance is a function of wind speed U and of the sea maturity. The influence of both factors on the altimeter measurements of wind speed, wave height, and radar cross section is studied experimentally on the basis of 1 year's worth of Geosat altimeter observations colocated with in situ wind and wave measurements by 20 NOAA buoys. Errors and biases in altimeter wind speed and wave height measurements are investigted. A geophysically significant error trend correlated with the sea maturity is found in wind-speed measurements. This trend is explained by examining the effect of the generalized wind fetch on the curves of the observed dependence. It is concluded that unambiguous measurements of wind speed by altimeter, in a wide range of <