Science.gov

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

  2. Sea Level Rise and Decadal Variations in the Ligurian Sea Inferred from the Medimaremetre Measurements.

    NASA Astrophysics Data System (ADS)

    Karpytchev, M.; Coulomb, A.; Vallee, M.

    2015-12-01

    Estimations of sea level rise over the last centuries are mostly based on the rare historical sea level records from tide gauge stations usually designed for navigational purposes. In this study, we examine the quality of sea level measurements performed by a mean sea level gauge operated in Nice from 1887 to 1909 and transferred to the nearby town of Villefranche-sur-Mer in 1913 where it stayed in operation untill 1974. The mean sea level gauges, called medimaremetres, were invented for geodetic studies and installed in many French ports since the end of the XIX century. By construction, the medimaremetre was connected to the sea through a porous porcelain crucible in order to filter out the tides and higher frequency sea level oscillations. Ucontrolled properties of the crucible and some systematic errors made the medimaremetre data to be ignored in the current sea level researches. We demonstrate that the Nice-Villefranche medimaremetre measurements are coherent with two available historical tide gauge records from Marseille and Genova and a new century-scale sea level series can be build up by combining the medimaremetre data with the those recorded by a tide gauge operating in Nice since the 1980s. We analyse the low frequency variabilities in Marseille, Nice-Villefranche and Genova and get new insights on the decadal sea level variations in the Ligurian Sea since the end of the XIX century.

  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.

  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. 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

  7. Measuring Sea Level Change (Vening Meinesz Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Woodworth, Philip L.

    2010-05-01

    For over 75 years, the Permanent Service for Mean Sea Level (PSMSL) at the Proudman Oceanographic Laboratory has maintained the global data bank for long term sea level change information from tide gauges. This data set has in recent years received most attention in studies of sea level rise related to climate change. However, it is also valuable in research into ocean circulation variability (oceanography), vertical land movements (geology) and geodetic datums (geodesy). This presentation will review some of the main applications of mean sea level information so far. In addition, it will point to the role of tide gauges within what is becoming a powerful combination of gauges, GPS, absolute gravity, satellite altimetry and space gravity for the study of sea and land level variations on a global basis. However, changes in mean levels are only one part of sea level research. Other topics include changes in extreme sea levels which are of practical importance as well as being interesting scientifically. Recent studies have begun to investigate changes in extremes worldwide, identifying those areas where secular changes in extremes tend to be determined by those in mean values, and areas where they are not. In addition, intriguing recent work has identified regional changes in ocean tides which are larger than expected from secular change in the tidal potential. Such tidal changes are also important within studies of extremes. This presentation will attempt to show the wide range of studies possible with a copious globally-distributed tide gauge data set, many of which are very relevant to the understanding of a changing world.

  8. Measuring progress of the global sea level observing system

    NASA Astrophysics Data System (ADS)

    Woodworth, Philip L.; Aarup, Thorkild; Merrifield, Mark; Mitchum, Gary T.; Le Provost, Christian

    Sea level is such a fundamental parameter in the sciences of oceanography geophysics, and climate change, that in the mid-1980s, the Intergovernmental Oceanographic Commission (IOC) established the Global Sea Level Observing System (GLOSS). GLOSS was to improve the quantity and quality of data provided to the Permanent Service for Mean Sea Level (PSMSL), and thereby, data for input to studies of long-term sea level change by the Intergovernmental Panel on Climate Change (IPCC). It would also provide the key data needed for international programs, such as the World Ocean Circulation Experiment (WOCE) and later, the Climate Variability and Predictability Programme (CLIVAR).GLOSS is now one of the main observation components of the Joint Technical Commission for Oceanography and Marine Meteorology (JCOMM) of IOC and the World Meteorological Organization (WMO). Progress and deficiencies in GLOSS were presented in July to the 22nd IOC Assembly at UNESCO in Paris and are contained in the GLOSS Assessment Report (GAR) [IOC, 2003a].

  9. Coastal sea level measurements using a single geodetic GPS receiver

    NASA Astrophysics Data System (ADS)

    Larson, Kristine M.; Löfgren, Johan S.; Haas, Rüdiger

    2013-04-01

    This paper presents a method to derive local sea level variations using data from a single geodetic-quality Global Navigation Satellite System (GNSS) receiver using GPS (Global Positioning System) signals. This method is based on multipath theory for specular reflections and the use of Signal-to-Noise Ratio (SNR) data. The technique could be valuable for altimeter calibration and validation. Data from two test sites, a dedicated GPS tide gauge at the Onsala Space Observatory (OSO) in Sweden and the Friday Harbor GPS site of the EarthScope Plate Boundary Observatory (PBO) in USA, are analyzed. The sea level results are compared to independently observed sea level data from nearby and in situ tide gauges. For OSO, the Root-Mean-Square (RMS) agreement is better than 5 cm, while it is in the order of 10 cm for Friday Harbor. The correlation coefficients are better than 0.97 for both sites. For OSO, the SNR-based results are also compared with results from a geodetic analysis of GPS data of a two receivers/antennae tide gauge installation. The SNR-based analysis results in a slightly worse RMS agreement with respect to the independent tide gauge data than the geodetic analysis (4.8 cm and 4.0 cm, respectively). However, it provides results even for rough sea surface conditions when the two receivers/antennae installation no longer records the necessary data for a geodetic analysis.

  10. 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.

  11. Sea level rise within the west of Arabian Gulf using tide gauge and continuous GPS measurements

    NASA Astrophysics Data System (ADS)

    Ayhan, M. E.; Alothman, A.

    2009-04-01

    Arabian Gulf is connected to Indian Ocean and located in the south-west of the Zagros Trust Belt. To investigate sea level variations within the west of Arabian Gulf, monthly means of sea level at 13 tide gauges along the coast of Saudi Arabia and Bahrain, available in the database of the Permanent Service for Mean Sea Level (PSMSL), are studied. We analyzed individually the monthly means at each station, and estimated secular sea level rate by a robust linear trend fitting. We computed the average relative sea level rise rate of 1.96 ± 0.21 mm/yr within the west of Arabian Gulf based on 4 stations spanning longer than 19 years. Vertical land motions are included into the relative sea level measurements at the tide gauges. Therefore sea level rates at the stations are corrected for vertical land motions using the ICE-5G v1.2 VM4 Glacial Isostatic Adjustment (GIA) model then we found the average sea level rise rate of 2.27 mm/yr. Bahrain International GPS Service (IGS) GPS station, which is close to the Mina Sulman tide gauge station in Bahrain, is the only continuous GPS station accessible in the region. The weekly GPS time series of vertical component at Bahrain IGS-GPS station referring to the ITRF97 from 1999.2 to 2008.6 are downloaded from http://www-gps.mit.edu/~tah/. We fitted a linear trend with an annual signal and one break to the GPS vertical time series and found a vertical land motion rate of 0.48 ± 0.11 mm/yr. Assuming the vertical rate at Bahrain IGS-GPS station represents the vertical rate at each of the other tide gauge stations studied here in the region, we computed average sea level rise rate of 2.44 ± 0.21 mm/yr within the west of Arabian Gulf.

  12. 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.

  13. Tectonic tilt rates derived from lake-level measurements, Salton Sea, California

    SciTech Connect

    Wilson, M.E.; Wood, S.H.

    1980-01-11

    Tectonic tilt at the Salton Sea was calculated by differencing lake-level measurements from two points on the sea. During the past 26 years, tilting was down toward the southeast. By 1970 differential vertical movement amounted to 110 millimeters between two gages situated 38 kilometers apart on the southwest shore. A reversal in tilt direction in late 1972 has diminished the net differential vertical movement to 60 millimeters.

  14. Tectonic tilt rates derived from lake-level measurements, salton sea, california.

    PubMed

    Wilson, M E; Wood, S H

    1980-01-11

    Tectonic tilt at the Salton Sea was calculated by differencing lake-level measurements from two points on the sea. During the past 26 years, tilting was down toward the southeast. By 1970 differential vertical movement amounted to 110 millimeters between two gages situated 38 kilometers apart on the southwest shore. A reversal in tilt direction in late 1972 has diminished the net differential vertical movement to 60 millimeters. PMID:17809103

  15. 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.

  16. 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.

  17. Electromagnetic bias of 36-GHz radar altimeter measurements of MSL. [Mean Sea Level

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Hancock, D. W., III; Hines, D. E.; Kenney, J. E.

    1984-01-01

    The data reduction techniques used to determine the magnitude of electromagnetic (EM) bias in radar altimeter measurements of mean sea level (MSL) area described. Particular attention is given to the bias reduction scheme developed specifically for the Surface Contour Radar (SCR) instrument of the Ocean Topography Experiment (TOPEX). The SCR makes it possible to determine the amount of the backscattered power due to EM reflectance per unit area by measuring both the return power and elevation. Variations of backscattered power for different sea states are determined as a function of displacement of the MSL. On the basis of the recent SCR observations from aircraft, a standard error due to EM bias is predicted for MSL measurements performed with a satellite altimeter radar operating at a frequency of 36 GHz. The obtained standard error was 1 percent for regions with waves 1.9-5.5 meters in height.

  18. 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

  19. 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.

  20. Radiation exposure at sea level measurement between Rio de Janeiro and the Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    De Freitas, A. C.; Alencar, A. S.; Coutinho, C. R.; Paschoa, A. S.

    2007-09-01

    A sea trip was made aboard the vessel NApOc Ary Rongel of the Brazilian Navy from Rio de Janeiro (Lat. 22°S) to Admiralty Bay (Lat. 62°S) in the King George Island in the Antarctic Peninsula. This trip was part of the Brazilian Antarctic Programme. Radiation measurements were carried out with a proportional counter along the ship round-trip route, which sailed partially under the South Atlantic Anomaly. Only those measurements, which were taken after the vessel was farther than one nautical mile offshore were used. This procedure minimizes radiation contributions from land. External radiation measurements made offshore give an indication of the secondary cosmic ray intensity at sea level. Barometric pressure measurements were registered along the round-trip route as well. Negative correlations between the measured external radiation and the barometric pressure on the vessel were observed in both ways of the round-trip. In latitudes above 42°S, the negative correlation became more prominent. In 1935 the variation of the secondary cosmic radiation with atmospheric pressure was known as the barometric paradox. Recently, an attempt was made to associate long-term variations of the surface pressure with solar activity and galactic cosmic rays. The results are discussed taking into account that as the barometric pressure increases the particle density in the atmosphere also increases. In such case, there are an increasing number of interactions with the particles produced in the hadronic showers, because of decreasing mean free path. Thus, the number of particles reaching a detector at the sea level decreases.

  1. 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

  2. Accuracy Assessment of GPS Buoy Sea Level Measurements for Coastal Applications

    NASA Astrophysics Data System (ADS)

    Chiu, S.; Cheng, K.

    2008-12-01

    The GPS buoy in this study contains a geodetic antenna and a compact floater with the GPS receiver and power supply tethered to a boat. The coastal applications using GPS include monitoring of sea level and its change, calibration of satellite altimeters, hydrological or geophysical parameters modeling, seafloor geodesy, and others. Among these applications, in order to understand the overall data or model quality, it is required to gain the knowledge of position accuracy of GPS buoys or GPS-equipped vessels. Despite different new GPS data processing techniques, e.g., Precise Point Positioning (PPP) and virtual reference station (VRS), that require a prioir information obtained from the a regional GPS network. While the required a prioir information can be implemented on land, it may not be available on the sea. Hence, in this study, the GPS buoy was positioned with respect to a onshore GPS reference station using the traditional double- difference technique. Since the atmosphere starts to decorrelate as the baseline, the distance between the buoy and the reference station, increases, the positioning accuracy consequently decreases. Therefore, this study aims to assess the buoy position accuracy as the baseline increases and in order to quantify the upper limit of sea level measured by the GPS buoy. A GPS buoy campaign was conducted by National Chung Cheng University in An Ping, Taiwan with a 8- hour GPS buoy data collection. In addition, a GPS network contains 4 Continuous GPS (CGPS) stations in Taiwan was established with the goal to enable baselines in different range for buoy data processing. A vector relation from the network was utilized in order to find the correct ambiguities, which were applied to the long-baseline solution to eliminate the position error caused by incorrect ambiguities. After this procedure, a 3.6-cm discrepancy was found in the mean sea level solution between the long (~80 km) and the short (~1.5 km) baselines. The discrepancy between a

  3. Improved sea level monitors for measuring vertical crustal deformation in the Shumagin seismic gap, Alaska

    NASA Technical Reports Server (NTRS)

    Hurst, Ken; Beavan, John

    1987-01-01

    The relative vertical deformation detection capability of a network of sea level gauges in the Shumagin seismic gap, Alaska has been improved. An examination of the present noise levels suggests that the network is now capable of providing relative deformation data that is quieter than data from leveling, GPS, VLBI, or satellite laser ranging.

  4. 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

  5. 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.

  6. Dtection of Sea Level Rise within the Arabian Gulf Using Space Based GNSS Measurements and Insitu Tide Gauge data

    NASA Astrophysics Data System (ADS)

    Alothman, Abdulaziz; Ayhan, Mehmet

    In the 21st century, sea level rise is expected to be about 30 cm or even more (up to 60 cm). Saudi Arabia has very long coasts of about 3400 km and hundreds of islands. Therefore, sea level monitoring may be important in particular along coastal low lands on Red Sea and Arabian Gulf coasts. Arabian Gulf is connected to Indian Ocean and lying along a parallel course in the south-west of the Zagros Trust Belt. We expect vertical land motion within the area due to both tectonic structures of the Arabian Peninsula and oil production activities. Global Navigation Satellite System (GNSS) Continues observations were used to estimate the vertical crustal motion. Bahrain International GPS Service (IGS-GPS) station is the only continuous GPS station accessible in the region, and it is close to the Mina Sulman tide gauge station in Bahrain. The weekly GPS time series of vertical component at Bahrain IGS-GPS station referring to the ITRF97 from 1999.2 to 2008.6 are used in the computation. We fitted a linear trend with an annual signal and a break to the GPS vertical time series and found a vertical land motion rate of 0.46 0.11 mm/yr. To investigate sea level variation within the west of Arabian Gulf, monthly means of sea level at 13 tide gauges along the coast of Saudi Arabia and Bahrain, available in the database of the Permanent Service for Mean Sea Level (PSMSL), are studied. We analyzed separately the monthly mean sea level measurements at each station, and estimated secular sea level rate by a robust linear trend fitting. We computed the average relative sea level rise rate of 1.96 0.21 mm/yr within the west of Arabian Gulf based on 4 stations spanning longer than 19 years. Sea level rates at the stations are first corrected for vertical land motion contamination using the ICE-5G v1.2 VM4 Glacial Isostatic Adjustment (GIA) model, and the average sea level rate is found 2.27 0.21 mm/yr. Assuming the vertical rate at Bahrain IGS-GPS station represents the vertical rate

  7. Projecting future sea level

    USGS Publications Warehouse

    Cayan, Daniel R.; Bromirski, Peter; Hayhoe, Katharine; Tyree, Mary; Dettinger, Mike; Flick, Reinhard

    2006-01-01

    California’s coastal observations and global model projections indicate that California’s open coast and estuaries will experience increasing sea levels over the next century. Sea level rise has affected much of the coast of California, including the Southern California coast, the Central California open coast, and the San Francisco Bay and upper estuary. These trends, quantified from a small set of California tide gages, have ranged from 10–20 centimeters (cm) (3.9–7.9 inches) per century, quite similar to that estimated for global mean sea level. So far, there is little evidence that the rate of rise has accelerated, and the rate of rise at California tide gages has actually flattened since 1980, but projections suggest substantial sea level rise may occur over the next century. Climate change simulations project a substantial rate of global sea level rise over the next century due to thermal expansion as the oceans warm and runoff from melting land-based snow and ice accelerates. Sea level rise projected from the models increases with the amount of warming. Relative to sea levels in 2000, by the 2070–2099 period, sea level rise projections range from 11–54 cm (4.3–21 in) for simulations following the lower (B1) greenhouse gas (GHG) emissions scenario, from 14–61 cm (5.5–24 in) for the middle-upper (A2) emission scenario, and from 17–72 cm (6.7–28 in) for the highest (A1fi) scenario. In addition to relatively steady secular trends, sea levels along the California coast undergo shorter period variability above or below predicted tide levels and changes associated with long-term trends. These variations are caused by weather events and by seasonal to decadal climate fluctuations over the Pacific Ocean that in turn affect the Pacific coast. Highest coastal sea levels have occurred when winter storms and Pacific climate disturbances, such as El Niño, have coincided with high astronomical tides. This study considers a range of projected future

  8. Rising Seas: Threat to Coastal Areas, A General Study about the Sea Level Rises on Coastal Areas of Earth, its Consequences and Preventive Measures.

    NASA Astrophysics Data System (ADS)

    Kataria, A.

    2015-12-01

    Scientific research indicates that sea levels worldwide have been rising at a rate of 3 millimeters per year since the early 1990s (IPCC), which is much higher than the previous century. The recent measurements (march 2015; NASA) tells us that the present rise of sea level is 64.4 mm. Most recent satellite measurements and tide gauge readings (NASA) tell us that present rate sea level rise is 3.20 mm per year. A recent study says we can expect the oceans to rise between 2.5 and 6.5 feet (0.8 and 2 meters) by 2100. The two main causes of rising seas are thermal expansion and glacier melting which further corresponds to the root cause of sea level rise: Green House effect. For every degree Celsius that global average temperature rises, we can expect 2.3 meters of sea-level rise sometime over the ensuing 2,000 years. The main consequence of Sea level rise is increase in oceanic acidity as it releases the entrapped carbon dioxide in between the glaciers. The problem goes from bad to worse when we take into consideration that one third of the world population lives in a 60 km range from the coast. In the event of a flood, this massive population would have to move away from the coasts. The main objective of research is to find all the most vulnerable areas, to make people aware about the consequences and to take proper measurements to fight with such natural calamities. The rise in sea level would inevitably cause massive migration like never seen before. Over 25% of the world population could disappear if sea levels continues to rise with same or faster rate as present. The oceans, sea life and life of people at coastal areas will get extremely effected unless there are considerable cuts in the carbon dioxide emissions. What we need to do is just to apply all the methods and measurements in our daily life that can help reduce the green house gases emissions. Also we need to plan that how to prevent all these cities in case of such natural hazards.

  9. 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.

  10. 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 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.

  11. 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

  12. 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.

  13. Sea level measurements using multi-frequency GPS and GLONASS observations

    NASA Astrophysics Data System (ADS)

    Löfgren, Johan S.; Haas, Rüdiger

    2014-12-01

    Global Positioning System (GPS) tide gauges have been realized in different configurations, e.g., with one zenith-looking antenna, using the multipath interference pattern for signal-to-noise ratio (SNR) analysis, or with one zenith- and one nadir-looking antenna, analyzing the difference in phase delay, to estimate the sea level height. In this study, for the first time, we use a true Global Navigation Satellite System (GNSS) tide gauge, installed at the Onsala Space Observatory. This GNSS tide gauge is recording both GPS and Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) signals and makes it possible to use both the one- and two-antenna analysis approach. Both the SNR analysis and the phase delay analysis were evaluated using dual-frequency GPS and GLONASS signals, i.e., frequencies in the L-band, during a 1-month-long campaign. The GNSS-derived sea level results were compared to independent sea level observations from a co-located pressure tide gauge and show a high correlation for both systems and frequency bands, with correlation coefficients of 0.86 to 0.97. The phase delay results show a better agreement with the tide gauge sea level than the SNR results, with root-mean-square differences of 3.5 cm (GPS L1 and L2) and 3.3/3.2 cm (GLONASS L1/L2 bands) compared to 4.0/9.0 cm (GPS L1/L2) and 4.7/8.9 cm (GLONASS L1/L2 bands). GPS and GLONASS show similar performance in the comparison, and the results prove that for the phase delay analysis, it is possible to use both frequencies, whereas for the SNR analysis, the L2 band should be avoided if other signals are available. Note that standard geodetic receivers using code-based tracking, i.e., tracking the un-encrypted C/A-code on L1 and using the manufacturers' proprietary tracking method for L2, were used. Signals with the new C/A-code on L2, the so-called L2 C , were not tracked. Using wind speed as an indicator for sea surface roughness, we find that the SNR analysis performs better in rough sea

  14. Dynamics of sea level variations in the coastal Red Sea

    NASA Astrophysics Data System (ADS)

    Churchill, James; Abulnaja, Yasser; Nellayaputhenpeedika, Mohammedali; Limeburner, Richard; Lentz, Steven

    2016-04-01

    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. While considerable scientific work has been directed at tidal and seasonal variations of Red Sea water level, very little attention has been given to elevation changes in an 'intermediate' frequency band, with periods of 2-30 d, even though motions in this band account for roughly half of the sea level variance in central Red Sea. We examined the sea level signal in this band using AVISO sea level anomaly (SLA) data, COARDAS wind data and measurements from pressure sensors maintained for more than five years at a number of locations in Saudi Arabian coastal waters. Empirical orthogonal function analysis of the SLA data indicates that longer-period (10-30 d) sea level variations in the intermediate band are dominated by coherent motions in a single mode that extends over most of the Red Sea axis. Idealized model results indicate that this large-scale mode of sea level motion is principally due to variations in the large-scale gradient of the along-axis wind. Our analysis indicates that coastal sea level motions at shorter periods (2-10 d) are principally generated by a combination of direct forcing by the local wind stress and forcing associated with large-scale wind stress gradients. However, also contributing to coastal sea level variations in the intermediate frequency band are mesoscale eddies, which are prevalent throughout the Red Sea basin, have a sea level signal of 10's of cm and produce relatively small-scale (order 50 km) changes in coastal sea level.

  15. 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.

  16. 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

  17. Analysis of sea level and sea surface temperature changes in the Black Sea

    NASA Astrophysics Data System (ADS)

    Betul Avsar, Nevin; Jin, Shuanggen; Kutoglu, Hakan; Erol, Bihter

    2016-07-01

    The Black Sea is a nearly closed sea with limited interaction with the Mediterranean Sea through the Turkish Straits. Measurement of sea level change will provide constraints on the water mass balance and thermal expansion of seawaters in response to climate change. In this paper, sea level changes in the Black Sea are investigated between January 1993 and December 2014 using multi-mission satellite altimetry data and sea surface temperature (SST) data. Here, the daily Maps of Sea Level Anomaly (MSLA) gridded with a 1/8°x1/8° spatial resolution from AVISO and the NOAA 1/4° daily Optimum Interpolation Sea Surface Temperature (OISST) Anomaly data set are used. The annual cycles of sea level and sea surface temperature changes reach the maximum values in November and January, respectively. The trend is 3.16±0.77 mm/yr for sea level change and -0.06±0.01°C/yr for sea surface temperature during the same 22-year period. The observed sea level rise is highly correlated with sea surface warming for the same time periods. In addition, the geographical distribution of the rates of the Black Sea level and SST changes between January 1993 and December 2014 are further analyzed, showing a good agreement in the eastern Black Sea. The rates of sea level rise and sea surface warming are larger in the eastern part than in the western part except in the northwestern Black Sea. Finally, the temporal correlation between sea level and SST time series are presented based on the Empirical Orthogonal Function (EOF) analysis.

  18. 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.

  19. A Study on Sea Level Variations of the Korean Peninsula and Surrounding Areas Based on Tide Gauge, GPS and Satellite Altimeter Measurements

    NASA Astrophysics Data System (ADS)

    Kim, K.; Park, K.; Won, J.

    2010-12-01

    Sea level variations of the Korean peninsula and surrounding areas in the ranges of 20-40 °N and 110-145 °E were investigated for the purpose of understanding the regional characteristics of the abnormal sea level rise near the Jeju island located in the southern edge of the Korean peninsula. For this study, we used tide gauge (TG) data, Global Positioning System (GPS) observations, and satellite altimeter measurements taken in the study area. We used the data at 194 TG stations. We obtained the TG data from 38 stations operated by Korea Hydrographic and Oceanographic Administration (KHOA) in Korea. We also collected monthly mean sea level observations from 139 and 17 TG stations of Japan and China, respectively. The data of Japan and China are from Global Sea Level Observing System (GLOSS) and Permanent Service for Mean Sea Level (PSMSL) services. We computed sea level rates using monthly mean sea level measurements, and analyzed spatial-temporal correlation through the Empirical Orthogonal Function (EOF) and Fast Fourier Transform (FFT) analysis. As the second part of our study, we derived absolute sea level rise rates by correcting the TG data for crustal deformation rates. To obtain the uplift rates in the area, we used continuous measurements at permanent GPS stations located at the TG site. For GPS data processing high-precision GPS data processing program GIPSY-OASIS II was used. To analyze local signatures of crustal deformation, we subtracted the primary EOF mode signal from the GPS height time series. Furthermore, we compared the obtained absolute sea level rates with satellite altimeter measurements. We obtained and analyzed TOPEX/Poseidon, Jason-1, and Jason-2 satellite altimeter data provided by AVISO from 1993 to 2010. We found that the absolute sea level rates from geodetic measurements are generally in good agreement with radar altimeter rates.

  20. 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

  1. 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.

  2. 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

  3. Contribution of vertical land motions to coastal sea level variations: a global synthesis of multisatellite altimetry, tide gauge and GPS measurements

    NASA Astrophysics Data System (ADS)

    Pfeffer, Julia; Allemand, Pascal

    2016-04-01

    Coastal sea level variations result from a complex mix of climatic, oceanic and geodynamical processes driven by natural and anthropogenic constraints. Combining data from multiple sources is one solution to identify particular processes and progress towards a better understanding of the sea level variations and the assessment of their impacts at coast. Here, we present a global database merging multisatellite altimetry with tide gauges and Global Positioning System (GPS) measurements. Vertical land motions and sea level variations are estimated simultaneously for a network of 886 ground stations with median errors lower than 1 mm/yr. The contribution of vertical land motions to relative sea level variations is explored to better understand the natural hazards associated with sea level rise in coastal areas. Worldwide, vertical land motions dominate 30 % of observed coastal trends. The role of the crust is highly heterogeneous: it can amplify, restrict or counter the effects of climate-induced sea level change. A set of 182 potential vulnerable localities are identified by large coastal subsidence which increases by several times the effects of sea level rise. Though regional behaviours exist, principally caused by GIA (Glacial Isostatic Adjustment), the local variability in vertical land motion prevails. An accurate determination of the vertical motions observed at the coast is fundamental to understand the local processes which contribute to sea level rise, to appraise its impacts on coastal populations and make future predictions.

  4. 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.)

  5. Accurately measuring sea level change from space: an ESA climate change initiative for MSL closure budget studies

    NASA Astrophysics Data System (ADS)

    Legeais, JeanFrancois; Benveniste, Jérôme

    2016-07-01

    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. The program is now in its second phase of 3 year (following phase I during 2011-2013). The objectives are firstly to involve the climate research community, to refine their needs and collect their feedbacks on product quality. And secondly 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. This has led to the production of a first version of the Sea Level ECV which has benefited from yearly extensions and now covers the period 1993-2014. Within phase II, new altimeter standards have been developed and tested in order to reprocess the dataset with the best standards for climate studies. The reprocessed ECV will be released in summer 2016. We will present the main achievements of the ESA CCI Sea Level Project. On the one hand, the major steps required to produce the 22 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

  6. A First Comparison of Simultaneous Sea Level Measurements from Envisat, GFO, Jason-1, and TOPEX/Poseidon

    PubMed Central

    Zhang, Caiyun; Chen, Ge

    2006-01-01

    The multiple altimeter missions have not only advanced our knowledge of ocean circulation, ice sheet topography, and global climate, but also improved the accuracy of altimetric measurements by cross-calibration and validation. In this paper, one year's simultaneous maps of sea level anomaly (MSLA) data obtained from four altimeters, Envisat, Geosat Follow-On (GFO), Jason-1, and TOPEX/Poseidon (T/P), have been compiled for a preliminary comparison. First, the discrepancy in global geographical distribution of each product relative to the merged MSLA field is analyzed and its signal retrieval capability is discussed. Second, the space/time variability of each discrepancy in the Atlantic Ocean, Indian Ocean, Pacific Ocean, Northern Hemisphere, Southern Hemisphere, and global ocean is studied. Third, each discrepancy as a function of latitude, longitude, and merged MSLA is presented. The results show that Jason-1 is the best single-mission for mapping large scale sea level variation, while T/P in its new orbit presents the poorest estimation of SLA due to the short period (from cycle 369 to 403) used to determine the mean profile. A clear understanding of each product discrepancy is necessary for a meaningful combination or merging of multi-altimeter data, optimal product selection, as well as for their assimilation into numerical models.

  7. 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.

  8. Long term statistical measurements of environmental acoustics parameters in the Arctic: Ambient noise levels in the West Greenland Sea

    NASA Astrophysics Data System (ADS)

    Buck, B. M.; Jaecks, D. W.

    1984-12-01

    Propagation loss data were taken using manned ice camps and aircraft, and ambient noise levels were measured using arctic data buoys that operated through the NIMBUS 6 and NOAA series satellites. The present report addresses one of a total of six arctic geographic areas - the West Greenland Sea, and presents ambient noise levels taken evvery three hours at the synoptic weather times from nine data buoys that drifted through the area. These data buoys collect a very large amount of independent measurements that are impractical to present in raw form. Therefore, a first-level statistical analysis was performed to allow reporting and distribution. These data, along with other regularly available meteorological, oceanographic and ice data, should enable higher order analyses and modeling for both prediction and understanding the mechanisms of arctic background noise. The data buoys, while limited in some respects, offer the only present means of long-term, wide-area investigations of arctic ambient noise on a true statistical basis.

  9. Intermittent sea-level acceleration

    NASA Astrophysics Data System (ADS)

    Olivieri, M.; Spada, G.

    2013-10-01

    Using instrumental observations from the Permanent Service for Mean Sea Level (PSMSL), we provide a new assessment of the global sea-level acceleration for the last ~ 2 centuries (1820-2010). Our results, obtained by a stack of tide gauge time series, confirm the existence of a global sea-level acceleration (GSLA) and, coherently with independent assessments so far, they point to a value close to 0.01 mm/yr2. However, differently from previous studies, we discuss how change points or abrupt inflections in individual sea-level time series have contributed to the GSLA. Our analysis, based on methods borrowed from econometrics, suggests the existence of two distinct driving mechanisms for the GSLA, both involving a minority of tide gauges globally. The first effectively implies a gradual increase in the rate of sea-level rise at individual tide gauges, while the second is manifest through a sequence of catastrophic variations of the sea-level trend. These occurred intermittently since the end of the 19th century and became more frequent during the last four decades.

  10. 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.

  11. Development of the Bulgarian Sea Level Service

    NASA Astrophysics Data System (ADS)

    Palazov, Atanas

    2013-04-01

    Systematic sea level measurements have been started in Bulgaria in the beginning of 20th century and nowadays there are 16 coastal sea level stations in operation. Operators of sea level stations are: National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences (NIMH) - 6 stations, Cadastre Agency, Ministry of Regional Development and Public Works (CA) - 4 stations, Port Infrastructure (PI) - 5 stations and Institute of Oceanology, Bulgarian Academy of Sciences (IO-BAS) - 1 station. Six of them are able to provide real time data. The sea level observations in the network of NIMH, performed at six main Bulgarian ports using standard poles, started in 1910. The program, implemented on the NIMH stations, includes daily measurements of the sea level with water gauges (poles). The position of a zero mark of the water gauge is checked once per year. The sea level network of the CA consists of 4 stations: Varna and Burgas (operational since 1928), Irakly and Ahtopol (since 1971). These stations are equipped with stilling-well tide gauges and with mechanical writing devices which draws sea level changes on paper. A mechanical paper writing instruments were installed in Varna and Burgas during 1928 and in 1971, a new paper writing instruments of type SUM (Russian) were installed in the stations of Irakly and Ahtopol. A set of five sea level stations in the ports of Balchik, Varna west, Pomorie, Burgas and Oil port Burgas was build during 2009 in the frame of Port Operational Marine Observing System (POMOS), equipped with high accuracy microwave instruments and operated by PI. In 2010 a new sea level station was set up in the IO-BAS coastal research base Shkorpolovtci. The station is equipped with high accuracy microwave instrument. These six stations are providing real time data. According to the decision of the Council of Ministers in 2012 sea level stations in Varna, Irakly, Burgas and Ahtopol will be operated jointly by Bulgarian Academy of Sciences and

  12. Tritium level along Romanian Black Sea Coast

    SciTech Connect

    Varlam, C.; Stefanescu, I.; Popescu, I.; Faurescu, I.

    2008-07-15

    Establishing the tritium level along the Romanian Black Sea Coast, after 10 years of exploitation of the nuclear power plant from Cernavoda, is a first step in evaluating its impact on the Black Sea ecosystem. The monitoring program consists of tritium activity concentration measurement in sea water and precipitation from Black Sea Coast between April 2005 and April 2006. The sampling points were spread over the Danube-Black Sea Canal - before the locks Agigea and Navodari, and Black Sea along the coast to the Bulgarian border. The average tritium concentration in sea water collected from the sampling locations had the value of 11.1 {+-} 2.1 TU, close to tritium concentration in precipitation. Although an operating nuclear power plant exists in the monitored area, the values of tritium concentration in two locations are slightly higher than those recorded elsewhere. To conclude, it could be emphasized that until now, Cernavoda NPP did not had any influence on the tritium concentration of the Black Sea Shore. (authors)

  13. Changes in extreme sea levels in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Dieterich, Christian; Gröger, Matthias; Andersson, Helén; Nerheim, Signild; Jönsson, Anette

    2016-04-01

    A newly developed shallow water model for the Baltic Sea and North Sea is presented. The model is validated by means of a comparison with hindcast simulations with observational data sets. The aim of the development is to provide and apply a modelling tool to model extreme sea levels in the Baltic Sea, Kattegat and Skagerrak. The model approach will support the direct analysis of extreme sea level observations in the past and provide the possibility to extend the statistical data base by producing very long time series or very large ensembles of coastal sea levels. This effort is intended to contribute to an assessment of risks due to storm surges and coastal flooding in the 21st century along the coast of Sweden. By using different RCP climate scenarios downscaled with a regional, coupled climate model atmospheric forcing is available to project possible changes in extreme sea levels into the future. Projected sea level rise, changes in dynamical sea level in the North East Atlantic and tidal forcing in the northern North Sea are applied as boundary condition which allows to investigate their impact on the dynamics of regional sea level variability. Initial experiments focus on the impact of model resolution, resolution in the atmospheric forcing and the amount of details necessary in the bathymetry to faithfully model coastal sea level in the Baltic Sea and North Sea.

  14. 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.

  15. 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

  16. 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.

  17. Sea Level Records from Geodetic GPS Receivers: a New Coastal Sea Level Dataset

    NASA Astrophysics Data System (ADS)

    Löfgren, J. S.; Haas, R.; Larson, K. M.; Scherneck, H.

    2012-12-01

    Global sea level rise and local sea level variations due to climate change has the potential for a significant impact on coastal societies. Thus, it is of great importance to monitor and understand how the sea level is changing. Existing techniques to measure sea level have provided important insights in this field during the last decades. However, further observations are necessary in order to fully understand the underlying processes. We present the possibility of a new coastal sea level dataset based on analysis of Signal-to-Noise Ratio (SNR) data from existing permanent GPS stations at the coast. For a GPS antenna close enough to the ocean, the multipath signals, reflected off the sea surface, interfere with the direct satellite signals. This becomes especially visible as oscillations in the recorded SNR data. The analysis of the SNR oscillations provides the distance between the sea surface and the GPS antenna phase center. Thus, such an installation can be called a GPS tide gauge and can be used to monitor sea level. The advantage of a GPS tide gauge is that it allows both determination of the sea level and determination of the position with respect to the International Terrestrial Reference Frame, using a single geodetic instrument. This is particularly valuable in areas with land surface motion where the usefulness of traditional tide gauges is restricted. The technique has been verified through comparison to traditional tide gauges at two sites. The comparison of more than three months long time series resulted in correlation coefficients of better than 0.97 for both sites. For the station with low and high tidal range, the root-mean-square agreement between the GPS results and the tide gauge records were better than 5 and 10 cm, respectively. In this presentation we show preliminary results for sea level records world wide by applying this technique to several existing permanent GPS stations.

  18. Sea Level Variability in the Mediterranean

    NASA Astrophysics Data System (ADS)

    Zerbini, S.; Bruni, S.; del Conte, S.; Errico, M.; Petracca, F.; Prati, C.; Raicich, F.; Santi, E.

    2015-12-01

    Tide gauges measure local sea-level relative to a benchmark on land, therefore the interpretation of these measurements can be limited by the lack of appropriate knowledge of vertical crustal motions. The oldest sea-level records date back to the 18th century; these observations are the only centuries-old data source enabling the estimate of historical sea-level trends/variations. In general, tide gauge benchmarks were not frequently levelled, except in those stations where natural and/or anthropogenic subsidence was a major concern. However, in most cases, it is difficult to retrieve the historical geodetic levelling data. Space geodetic techniques, such as GNSS, Doris and InSAR are now providing measurements on a time and space-continuous basis, giving rise to a large amount of different data sets. The vertical motions resulting from the various analyses need to be compared and best exploited for achieving reliable estimates of sea level variations. In the Mediterranean area, there are a few centennial tide gauge records; our study focuses, in particular, on the Italian time series of Genoa, Marina di Ravenna, Venice and Trieste. Two of these stations, Marina di Ravenna and Venice, are affected by both natural and anthropogenic subsidence, the latter was particularly intense during a few decades of the 20th century because of ground fluids withdrawal. We have retrieved levelling data of benchmarks at and/or close to the tide gauges from the end of 1800 and, for the last couple of decades, also GPS and InSAR height time series in close proximity of the stations. By using an ensemble of these data, modelling of the long-period non-linear behavior of subsidence was successfully accomplished. After removal of the land vertical motions, the linear long period sea-level rates of all stations are in excellent agreement. Over the last two decades, the tide gauge rates were also compared with those obtained by satellite radar altimetry data.

  19. 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.

  20. 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.

  1. The future for the Global Sea Level Observing System (GLOSS) Sea Level Data Rescue

    NASA Astrophysics Data System (ADS)

    Bradshaw, Elizabeth; Matthews, Andrew; Rickards, Lesley; Aarup, Thorkild

    2016-04-01

    Historical sea level data are rare and unrepeatable measurements with a number of applications in climate studies (sea level rise), oceanography (ocean currents, tides, surges), geodesy (national datum), geophysics and geology (coastal land movements) and other disciplines. However, long-term time series are concentrated in the northern hemisphere and there are no records at the Permanent Service for Mean Sea Level (PSMSL) global data bank longer than 100 years in the Arctic, Africa, South America or Antarctica. Data archaeology activities will help fill in the gaps in the global dataset and improve global sea level reconstruction. The Global Sea Level Observing System (GLOSS) is an international programme conducted under the auspices of the WMO-IOC Joint Technical Commission for Oceanography and Marine Meteorology. It was set up in 1985 to collect long-term tide gauge observations and to develop systems and standards "for ocean monitoring and flood warning purposes". At the GLOSS-GE-XIV Meeting in 2015, GLOSS agreed on a number of action items to be developed in the next two years. These were: 1. To explore mareogram digitisation applications, including NUNIEAU (more information available at: http://www.mediterranee.cerema.fr/logiciel-de-numerisation-des-enregistrements-r57.html) and other recent developments in scanning/digitisation software, such as IEDRO's Weather Wizards program, to see if they could be used via a browser. 2. To publicise sea level data archaeology and rescue by: • maintaining and regularly updating the Sea Level Data Archaeology page on the GLOSS website • strengthening links to the GLOSS data centres and data rescue organisations e.g. linking to IEDRO, ACRE, RDA • restarting the sea level data rescue blog with monthly posts. 3. Investigate sources of funding for data archaeology and rescue projects. 4. Propose "Guidelines" for rescuing sea level data. These action items will aid the discovery, scanning, digitising and quality control

  2. Sea Level Change, A Fundamental Process When Interpreting Coastal Geology and Geography.

    ERIC Educational Resources Information Center

    Zeigler, John M.

    1985-01-01

    Discusses the meaning of sea level change and identifies the major factors responsible for this occurrence. Elaborates on the theory and processes involved in indirect measurement of changes in sea volume. Also explains how crustal movement affects sea level. (ML)

  3. A NOAA/NOS Sea Level Advisory

    NASA Astrophysics Data System (ADS)

    Sweet, W.

    2011-12-01

    In order for coastal communities to realize current impacts and become resilient to future changes, sea level advisories/bulletins are necessary that systematically monitor and document non-tidal anomalies (residuals) and flood-watch (elevation) conditions. The need became apparent after an exceptional sea level anomaly along the U.S. East Coast in June - July of 2009 when higher than normal sea levels coincided with a perigean-spring tide and flooded many coastal regions. The event spurred numerous public inquiries to the National Oceanic and Atmospheric Administration's (NOAA) Center for Operational Oceanographic Products and Services (CO-OPS) from coastal communities concerned because of the lack of any coastal storm signatures normally associated with such an anomaly. A subsequent NOAA report provided insight into some of the mechanisms involved in the event and methods for tracking their reoccurrences. NOAA/CO-OPS is the U.S. authority responsible for defining sea level datums and tracking their relative changes in support of marine navigation and national and state land-use boundaries. These efforts are supported by the National Water Level Observation Network (NWLON), whose long-term and widespread observations largely define a total water level measurement impacting a coastal community. NWLON time series provide estimates of local relative sea level trends, a product increasingly utilized by various stakeholders planning for the future. NWLON data also capture significant short-term changes and conveyance of high-water variations (from surge to seasonal scale) provides invaluable insight into inundation patterns ultimately needed for a more comprehensive planning guide. A NOAA/CO-OPS Sea Level Advisory Project will enhance high-water monitoring capabilities by: - Automatically detecting sea level anomalies and flood-watch occurrences - Seasonally calibrating the anomaly thresholds to a locality in terms of flood potential - Alerting for near

  4. Identifying the sea level signal: Surf's up

    NASA Astrophysics Data System (ADS)

    Maggs, William Ward

    Of all the dire consequences of the greenhouse effect, global sea level rise is potentially the most destructive to human life and property. But the processes that increase the volume of the oceans are so poorly understood that theoreticians are taking their lead from scientists trying to actually measure current changes in sea level that might be caused by the greenhouse effect. As with surface temperature, precipitation, and other measures of climate change, identifying the greenhouse signal is a daunting problem.Climate models that predict mean temperature increases around the world of up to several degrees C in the next 50-100 years in response to human-induced global warming have given rise to a scientific consensus that mountain glaciers and ice sheets will begin to melt and the water in oceans will slightly expand, raising sea level. Such increases would inundate some of the most densely populated and highly cultivated areas on the planet, displacing and endangering many millions of people at a devastating economic and social cost.

  5. Sea-level changes before large earthquakes

    USGS Publications Warehouse

    Wyss, M.

    1978-01-01

    Changes in sea level have long been used as a measure of local uplift and subsidence associated with large earthquakes. For instance, in 1835, the British naturalist Charles Darwin observed that sea level dropped by 2.7 meters during the large earthquake in Concepcion, CHile. From this piece of evidence and the terraces along the beach that he saw, Darwin concluded that the Andes had grown to their present height through earthquakes. Much more recently, George Plafker and James C. Savage of the U.S Geological Survey have shown, from barnacle lines, that the great 1960 Chile and the 1964 Alaska earthquakes caused several meters of vertical displacement of the shoreline. 

  6. 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.

  7. On sea level - ice sheet interactions

    NASA Astrophysics Data System (ADS)

    Gomez, Natalya Alissa

    This thesis focuses on the physics of static sea-level changes following variations in the distribution of grounded ice and the influence of these changes on the stability and dynamics of marine ice sheets. Gravitational, deformational and rotational effects associated with changes in grounded ice mass lead to markedly non-uniform spatial patterns of sea-level change. I outline a revised theory for computing post-glacial sea-level predictions and discuss the dominant physical effects that contribute to the patterns of sea-level change associated with surface loading on different timescales. I show, in particular, that a large sea-level fall (rise) occurs in the vicinity of a retreating (advancing) ice sheet on both short and long timescales. I also present an application of the sea-level theory in which I predict the sea-level changes associated with a new model of North American ice sheet evolution and consider the implications of the results for efforts to establish the sources of Meltwater Pulse 1A. These results demonstrate that viscous deformational effects can influence the amplitude of sea-level changes observed at far-field sea-level sites, even when the time window being considered is relatively short (≤ 500 years). Subsequently, I investigate the feedback of sea-level changes on marine ice-sheet stability and dynamics by coupling a global sea-level model to ice-sheet models of increasing complexity. To begin, I incorporate gravitationally self-consistent sea-level changes into an equilibrium marine ice-sheet stability theory to show that the sea-level changes have a stabilizing influence on ice-sheet retreat. Next, I consider the impact of the stabilizing mechanism on the timescale of ice-sheet retreat using a 1D dynamic coupled ice sheet - sea level model. Simulations with the coupled model, which incorporate viscoelastic deformation of the solid Earth, show that local sea-level changes at the grounding line act to slow, and in some cases, halt

  8. 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.

  9. 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.

  10. 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).

  11. Causes for contemporary regional sea level changes.

    PubMed

    Stammer, Detlef; Cazenave, Anny; Ponte, Rui M; Tamisiea, Mark E

    2013-01-01

    Regional sea level changes can deviate substantially from those of the global mean, can vary on a broad range of timescales, and in some regions can even lead to a reversal of long-term global mean sea level trends. The underlying causes are associated with dynamic variations in the ocean circulation as part of climate modes of variability and with an isostatic adjustment of Earth's crust to past and ongoing changes in polar ice masses and continental water storage. Relative to the coastline, sea level is also affected by processes such as earthquakes and anthropogenically induced subsidence. Present-day regional sea level changes appear to be caused primarily by natural climate variability. However, the imprint of anthropogenic effects on regional sea level-whether due to changes in the atmospheric forcing or to mass variations in the system-will grow with time as climate change progresses, and toward the end of the twenty-first century, regional sea level patterns will be a superposition of climate variability modes and natural and anthropogenically induced static sea level patterns. Attribution and predictions of ongoing and future sea level changes require an expanded and sustained climate observing system.

  12. Ancient sea-level swings confirmed

    SciTech Connect

    Kerr, R.A.

    1996-05-24

    Geologic benchmarks long touted and documented by Exxon scientists along the edges of continents record changes in global sea levels. However the driving force behind the holdest sea-level shifts remains mysterious, including ice sheet melting and forming and climatic change. This article discussed both the findings and the speculation about why the fluctuations took place.

  13. Monitoring coastal sea level using reflected GNSS signals

    NASA Astrophysics Data System (ADS)

    Löfgren, Johan S.; Haas, Rüdiger; Johansson, Jan M.

    2011-01-01

    A continuous monitoring of coastal sea level changes is important for human society since it is predicted that up to 332 million people in coastal and low-lying areas will be directly affected by flooding from sea level rise by the end of the 21st century. The traditional way to observe sea level is using tide gauges that give measurements relative to the Earth’s crust. However, in order to improve the understanding of the sea level change processes it is necessary to separate the measurements into land surface height changes and sea surface height changes. These measurements should then be relative to a global reference frame. This can be done with satellite techniques, and thus a GNSS-based tide gauge is proposed. The GNSS-based tide gauge makes use of both GNSS signals that are directly received and GNSS signals that are reflected from the sea surface. An experimental installation at the Onsala Space Observatory (OSO) shows that the reflected GNSS signals have only about 3 dB less signal-to-noise-ratio than the directly received GNSS signals. Furthermore, a comparison of local sea level observations from the GNSS-based tide gauge with two stilling well gauges, located approximately 18 and 33 km away from OSO, gives a pairwise root-mean-square agreement on the order of 4 cm. This indicates that the GNSS-based tide gauge gives valuable results for sea level monitoring.

  14. 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

  15. The Caribbean conundrum of Holocene sea level.

    NASA Astrophysics Data System (ADS)

    Jackson, Luke; Mound, Jon

    2014-05-01

    In the tropics, pre-historic sea-level curve reconstruction is often problematic because it relies upon sea-level indicators whose vertical relationship to the sea surface is poorly constrained. In the Caribbean, fossil corals, mangrove peats and shell material dominate the pre-historic indicator record. The common approach to reconstruction involves the use of modern analogues to these indicators to establish a fixed vertical habitable range. The aim of these reconstructions is to find spatial variability in the Holocene sea level in an area gradually subsiding (< 1.2 mm yr-1) due the water loading following the deglaciation of the Laurentide ice sheet. We construct two catalogues: one of published Holocene sea-level indicators and the other of published, modern growth rates, abundance and coverage of mangrove and coral species for different depths. We use the first catalogue to calibrate 14C ages to give a probabilistic age range for each indicator. We use the second catalogue to define a depth probability distribution function (pdf) for mangroves and each coral species. The Holocene indicators are grouped into 12 sub-regions around the Caribbean. For each sub-region we apply our sea-level reconstruction, which involves stepping a fixed-length time window through time and calculating the position (and rate) of sea-level (change) using a thousand realisations of the time/depth pdfs to define an envelope of probable solutions. We find that the sub-regional relative sea-level curves display spatio-temporal variability including a south-east to north-west 1500 year lag in the arrival of Holocene sea level to that of the present day. We demonstrate that these variations are primarily due to glacial-isostatic-adjustment induced sea-level change and that sub-regional variations (where sufficient data exists) are due to local uplift variability.

  16. 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

  17. Acceleration of Sea Level Rise Over Malaysian Seas from Satellite Altimeter

    NASA Astrophysics Data System (ADS)

    Hamid, A. I. A.; Din, A. H. M.; Khalid, N. F.; Omar, K. M.

    2016-09-01

    Sea level rise becomes our concern nowadays as a result of variously contribution of climate change that cause by the anthropogenic effects. Global sea levels have been rising through the past century and are projected to rise at an accelerated rate throughout the 21st century. Due to this change, sea level is now constantly rising and eventually will threaten many low-lying and unprotected coastal areas in many ways. This paper is proposing a significant effort to quantify the sea level trend over Malaysian seas based on the combination of multi-mission satellite altimeters over a period of 23 years. Eight altimeter missions are used to derive the absolute sea level from Radar Altimeter Database System (RADS). Data verification is then carried out to verify the satellite derived sea level rise data with tidal data. Eight selected tide gauge stations from Peninsular Malaysia, Sabah and Sarawak are chosen for this data verification. The pattern and correlation of both measurements of sea level anomalies (SLA) are evaluated over the same period in each area in order to produce comparable results. Afterwards, the time series of the sea level trend is quantified using robust fit regression analysis. The findings clearly show that the absolute sea level trend is rising and varying over the Malaysian seas with the rate of sea level varies and gradually increase from east to west of Malaysia. Highly confident and correlation level of the 23 years measurement data with an astonishing root mean square difference permits the absolute sea level trend of the Malaysian seas has raised at the rate 3.14 ± 0.12 mm yr-1 to 4.81 ± 0.15 mm yr-1 for the chosen sub-areas, with an overall mean of 4.09 ± 0.12 mm yr-1. This study hopefully offers a beneficial sea level information to be applied in a wide range of related environmental and climatology issue such as flood and global warming.

  18. 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.

  19. 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.

    2016-06-01

    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-5G 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 per cent decrease and an average ˜20-25 per cent increase to the load thickness relative to the ICE-5G 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-5G 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-5G 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-6G model. The volume history of the Laur16 reconstruction corresponds to an up to 8 m reduction in global sea level equivalent compared to ICE-5G at LGM.

  20. Satellite Altimeter Observations of Black Sea Level Variations

    NASA Technical Reports Server (NTRS)

    Korotaev, G. K.; Saenko, O. A.; Koblinsky, C. J.

    1998-01-01

    Satellite altimeter data from TOPEX/POSEIDON and ERS-1 are used to examine seasonal and mesoscale variability of the Black Sea level. Consistent processing procedures of the altimeter measurements make it possible to determine the dynamical Black Sea level with an rms accuracy about 3 cm. It is shown that the Black Sea circulation intensifies in the winter-spring seasons and attenuates in summer-autumn. The seasonal variability of sea level is accompanied by a radiation of Rossby waves from the eastern coast of the basin. Mesoscale oscillations of the dynamical sea level are found to vary spatially and temporarily. Usually, strong eddy intensity is associated with instabilities of the Rim Current. Away from this circulation feature, in the deep basin, mesoscale variability is much smaller. Mesoscale variability has a strong seasonal signal, which is out of phase with the strength of the Rim Current.

  1. Differences between mean tide level and mean sea level

    NASA Astrophysics Data System (ADS)

    Woodworth, P. L.

    2016-07-01

    This paper discusses the differences between mean tide level (MTL) and mean sea level (MSL) as demonstrated using information from a global tide gauge data set. The roles of the two main contributors to differences between MTL and MSL (the M4 harmonic of the M2 semidiurnal tide, and the combination of the diurnal tides K1 and O1) are described, with a particular focus on the spatial scales of variation in MTL-MSL due to each contributor. Findings from the tide gauge data set are contrasted with those from a state-of-the-art global tide model. The study is of interest within tidal science, but also has practical importance regarding the type of mean level used to define land survey datums. In addition, an appreciation of MTL-MSL difference is important in the use of the historical sea level data used in climate change research, with implications for some of the data stored in international databanks. Particular studies are made of how MTL and MSL might differ through the year, and if MTL is measured in daylight hours only, as has been the practice of some national geodetic agencies on occasions in the past.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. Variability In The Solomon Sea From Altimetric Sea Level Data

    NASA Astrophysics Data System (ADS)

    Melet, A.; Gourdeau, L.; Kessler, W.; Verron, J.

    2007-12-01

    In the southwest tropical Pacific, subtropical waters from the SEC flow in the Solomon Sea, mainly through the western boundary New Guinea Coastal Undercurrent, and join the equatorial western Pacific by three narrow straits. The NGCU transports part of the spiciness anomalies generated in the South East Pacific and subducted in the thermocline. Because the NGCU is a primary source of the EUC, variations of its characteristics are expected to play a role in the equatorial thermocline features and more generally on decadal climate variability. Therefore, the study of the Solomon Sea is a key issue of the SPICE program. In this study, we focus on the variability of the Solomon Sea in term of sea level. The Solomon Sea is semi closed with a complex topography and numerous islands. Thus, the use of classical gridded altimetric products is inadequate. Consequently, this work is based on original along track Topex/Poseidon data. New data processing (CTOH/LEGOS) has been applied to recover proper data and to gain more information on the altimetric signal in this region. A track-by-track specific and customized post processing has been used to finalize the dataset. These new altimetric data have been assessed against tide gauge data. The analysis of the resulting sea level anomalies exhibits the highest variability observed in the tropical Pacific in an area centred near 8°S and expanding from each side of the Solomon Islands, outside of the WBC. Sea level variability presents a wide temporal spectrum, from intraseasonal to interannual ranges with the notable influence of the monsoon and of ENSO. In the Solomon Sea, three frequencies emerge : 60, 365 and 2000 days. The 60-days frequency seems particularly important in the Solomon Sea compared with the surrounding waters and an EOF analysis is used to understand its features. We also depict the signature of the New Guinea Coastal Current (NGCC), the western boundary current flowing north along the eastern coast of Papua

  7. Nonlinear trends and multiyear cycles in sea level records

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

    We analyze the Permanent Service for Mean Sea Level (PSMSL) database of sea level time series using a method based on Monte Carlo Singular Spectrum Analysis (MC-SSA). We remove 2-30 year quasi-periodic oscillations and determine the nonlinear long-term trends for 12 large ocean regions. Our global sea level trend estimate of 2.4 ± 1.0 mm/yr for the period from 1993 to 2000 is comparable with the 2.6 ± 0.7 mm/yr sea level rise calculated from TOPEX/Poseidon altimeter measurements. However, we show that over the last 100 years the rate of 2.5 ± 1.0 mm/yr occurred between 1920 and 1945, is likely to be as large as the 1990s, and resulted in a mean sea level rise of 48 mm. We evaluate errors in sea level using two independent approaches, the robust bi-weight mean and variance, and a novel "virtual station" approach that utilizes geographic locations of stations. Results suggest that a region cannot be adequately represented by a simple mean curve with standard error, assuming all stations are independent, as multiyear cycles within regions are very significant. Additionally, much of the between-region mismatch errors are due to multiyear cycles in the global sea level that limit the ability of simple means to capture sea level accurately. We demonstrate that variability in sea level records over periods 2-30 years has increased during the past 50 years in most ocean basins.

  8. Sea Level Rise Impacts On Infrastructure Vulnerability

    NASA Astrophysics Data System (ADS)

    Pasqualini, D.; Mccown, A. W.; Backhaus, S.; Urban, N. M.

    2015-12-01

    Increase of global sea level is one of the potential consequences of climate change and represents a threat for the U.S.A coastal regions, which are highly populated and home of critical infrastructures. The potential danger caused by sea level rise may escalate if sea level rise is coupled with an increase in frequency and intensity of storms that may strike these regions. These coupled threats present a clear risk to population and critical infrastructure and are concerns for Federal, State, and particularly local response and recovery planners. Understanding the effect of sea level rise on the risk to critical infrastructure is crucial for long planning and for mitigating potential damages. In this work we quantify how infrastructure vulnerability to a range of storms changes due to an increase of sea level. Our study focuses on the Norfolk area of the U.S.A. We assess the direct damage of drinking water and wastewater facilities and the power sector caused by a distribution of synthetic hurricanes. In addition, our analysis estimates indirect consequences of these damages on population and economic activities accounting also for interdependencies across infrastructures. While projections unanimously indicate an increase in the rate of sea level rise, the scientific community does not agree on the size of this rate. Our risk assessment accounts for this uncertainty simulating a distribution of sea level rise for a specific climate scenario. Using our impact assessment results and assuming an increase of future hurricanes frequencies and intensities, we also estimate the expected benefits for critical infrastructure.

  9. Post-Cromerian rise in sea level

    SciTech Connect

    Olausson, E.

    1992-03-01

    The intensified cooling in the northern hemisphere during the Elsterian-Saalian ice ages (isotopic stages 22-6) resulted in a reduction of the Antarctic ice sheet by 10-15 x 106 km3, equal to a rise in sea level by about 40 m. This rise in sea level changed the hydrography of the Black Sea during the late Pleistocene warmer times, caused anoxic conditions in the eastern Mediterranean during the corresponding warming-up phases, and enhanced water transport of less saline water from the Pacific into the Arctic Ocean (the present sill depth of the Bering Strait is about 50 m). The increased supply of less saline water strengthened the halocline in the Arctic Ocean, increasing the sea ice there and, by higher albedo, its cooling effect on the adjacent continents.

  10. 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.

  11. 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.

  12. 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

  13. Sea level trend and variability around Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    are estimated at 4.4±3.1 and 4.6±2.5 mm yr-1. The geocentric rates are about 25 % faster than those measured at tide gauges around the peninsula; however, the level of uncertainty associated with VLM data is relatively high. For the common period between 1993 and 2009, geocentric sea level rise values along the Malaysian coast are similar from tide gauge records and satellite altimetry (3.1 and 2.7 mm yr-1, respectively), and arguably correspond to the global trend.

  14. Upper Limit for Regional Sea Level Projections

    NASA Astrophysics Data System (ADS)

    Jevrejeva, Svetlana; Jackson, Luke; Riva, Riccardo; Grinsted, Aslak; Moore, John

    2016-04-01

    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. With probabilistic approach we produce regional sea level projections taking into account large uncertainties associated with Greenland and Antarctica ice sheets contribution. We calculate the upper limit (as 95%) for regional sea level projections by 2100 with RCP8.5 scenario, suggesting that for the most coastlines upper limit will exceed the global upper limit of 1.8 m.

  15. A new perspective on global mean sea level (GMSL) acceleration

    NASA Astrophysics Data System (ADS)

    Watson, Phil J.

    2016-06-01

    The vast body of contemporary climate change science is largely underpinned by the premise of a measured acceleration from anthropogenic forcings evident in key climate change proxies -- greenhouse gas emissions, temperature, and mean sea level. By virtue, over recent years, the issue of whether or not there is a measurable acceleration in global mean sea level has resulted in fierce, widespread professional, social, and political debate. Attempts to measure acceleration in global mean sea level (GMSL) have often used comparatively crude analysis techniques providing little temporal instruction on these key questions. This work proposes improved techniques to measure real-time velocity and acceleration based on five GMSL reconstructions spanning the time frame from 1807 to 2014 with substantially improved temporal resolution. While this analysis highlights key differences between the respective reconstructions, there is now more robust, convincing evidence of recent acceleration in the trend of GMSL.

  16. Mean sea level determination from satellite altimetry

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    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 m 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. After one year's operations of the altimeter, data from over 5000 altimeter passes have been collected. With the mathematical models developed and the altimeter data presently available, mapping of local areas of ocean topography has been realized to the planned accuracy levels and better. This paper presents the basic data processing methods employed and some interesting results achieved with the early data. Plots of mean sea surface heights as inferred by the altimeter measurements are compared with a detailed 1 by 1 deg gravimetric geoid.

  17. Regional patterns of low-frequency sea level variability: case of the Japan/East Sea

    NASA Astrophysics Data System (ADS)

    Trusenkova, Olga

    An increasing trend is detected in globally averaged sea level derived from satellite altimetry measurements for the last two decades. Sea level trends in the North Pacific can be attributed to steric expansion, mostly due to the temperature increase, while the spatial distribution resembles the negative phase of Pacific Decadal Oscillation (PDO). The latter is attributed to water redistribution caused by circulation (Fukumore, Wang, 2013). As for the East Asia marginal seas, there are strong positive sea level trends in the subtropical areas but only weak positive or even negative trends in the subarctic areas (Marcos et al., 2012). Strong seasonal sea level oscillations, with amplitude of 15-25 cm, occur simultaneously in the entire Japan/East Sea, with maxima and minima in October and March, respectively (Choi et al., 2004; Trusenkova et al., 2010). The timing of the extremes can be explained by maximum inflow of warm water through the Korea Strait in October and strong winter cooling. This study is focused on low-frequency sea level variability in the Japan/East Sea, beyond the steric effects. To this purpose, AVISO 0.25 dergee gridded weekly sea level anomalies (SLA) for the period from October 1992 onwards are low-pass filtered, with the cut-off period of 1.3 years. Decomposition to Empirical Orthogonal Functions (EOF) yields the leading mode of synchronous, weak but statistically significant, quasi-biennial oscillations in the entire Sea. They also manifest interannual and decadal variability but no linear trend. This mode should be attributed to variation of water volume in the sea, i.e. transport imbalance through the straits. The strong SLA are timed with the strong anomalies of the inflow transport in the Korea Strait. An out-of-phase relationship of sea level with PDO was found and explained by transport variations in the Korea Strait (Gordon and Giulivi, 2004). However, the alternating out-of-phase and in-phase regimes are detected when the altimetry

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Low frequency Sea Level Variability: correlation between altimetry and tide gauges in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Bonaduce, A.; Pinardi, N.

    2012-04-01

    Sea level variability in the Mediterranean Sea over the decadal time scale is studied using a combination of sea level and in-situ observations. A method to decompose the different sea level signals for tide gauges and altimetry is proposed, so that a coherent comparison between the two measurements is possible. The steric component and the atmospheric pressure contribution (inverse barometer) are filtered in order to look at sea level changes over decadal time scales. Low frequency sea level from tide gauges data is found to be representative of a large scale signal and results to be comparable, along all the basin, with satellite altimetry data. In particular the two signals are better correlated in the areas where the continental shelf is extended, such as the northern Adriatic. The same occurs in the case where the tide gauge station is located on an island, such as Malta, where the station is representative of the open ocean sea level signal. Moving towards the Levantin basin, the shelves extension generally decrease and the two data sets tend to be less correlated even if still correlated positively with a root mean square error lower than 5 cm (Hadera, Israel). Looking at the sea level trend, a positive trend of 2.15 ± 0.7 mm yr -1 is observed in the Mediterranean basin considering satellite altimetry during the period from 1993 to 2010 . Glacial Isostatic Adjustment (GIA) has been considered correcting sea level data with ICE-5G model data. This value represent just and index of the sea level changes occurring at basin scale. The basin presents a marked trend spatial variability, mainly characterized by strong positive trends in the shelves areas and negative trends in the Ionian sea, due to a strong change in the circulation in this basin. The variability of the trend values as a function of the number of years considered is such that at least 15 years of data are needed in order to obtain a significant and stable positive trend. The total lack of in

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. Quantitative constraints on the sea-level fall that terminated the Littorina Sea Stage, southern Scandinavia

    NASA Astrophysics Data System (ADS)

    Clemmensen, Lars B.; Murray, Andrew S.; Nielsen, Lars

    2012-04-01

    The island of Anholt in the Kattegat sea (southern Scandinavia) is made up largely of an extensive beach-ridge plain. As a result of post-glacial uplift, the earliest beach-ridge and swale deposits are now raised 8-9 m above present mean sea level. It appears that growth of the plain has been almost uninterrupted over the past 7500 years; here we constrain the evolution of this plain between 6300 and 1300 years ago using optically stimulated luminescence dates. The topography and internal architecture of the fossil shoreline deposits were measured on high-resolution maps and in ground-penetrating radar (GPR) reflection data with a vertical resolution of ˜0.25 m. Shoreline topography shows significant changes with time, and it appears that one of the most striking changes took place between 4300 and 3600 years ago; in the shoreline deposits corresponding to this time interval the surface drops by around 3.5 m suggesting a marked fall in relative sea-level. Assuming a constant uplift rate of 1.2 mm/yr, the corresponding drop in absolute sea-level is estimated to be around 2.6 m. This marked sea-level fall in 700 years took place at the transition from the Middle Holocene Thermal Maximum to the Late Holocene Thermal Decline or at the end of the Littorina Sea stage in the Baltic Sea region.

  9. 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.

  10. Sea-Level Changes during the Tertiary.

    ERIC Educational Resources Information Center

    Vail, Peter R.; Hardenbol, Jan

    1979-01-01

    Discussed are research procedures undertaken to determine the magnitude and timing of eustatic sea-level changes during the Tertiary Period. Data now becoming available give scientists a knowledge of conditions that may have been conducive to the formation of petroleum. (BT)

  11. Trends in UK mean sea level revisited

    NASA Astrophysics Data System (ADS)

    Woodworth, P. L.; Teferle, F. N.; Bingley, R. M.; Shennan, I.; Williams, S. D. P.

    2009-01-01

    This paper presents estimates of rates of mean sea level (MSL) change around the UK, based on a larger tide gauge data set and more accurate analysis methods than have been employed so far. The spatial variation of the trend in MSL is found to be similar to that inferred from geological information and from advanced geodetic techniques, which is a similar conclusion to that arrived at in the previous studies. The tide gauge MSL trends for 1901 onwards are estimated to be 1.4 +/- 0.2 mm yr-1 larger than those inferred from geology or geodetic methods, suggesting a regional sea level rise of climate change origin several one-tenths of mm per year lower than global estimates for the 20th century. However, UK MSL change cannot be described in terms of a simple linear increase alone but includes variations on interannual and decadal timescales. The possible sources of variation in a `UK sea level index' are explored. Air pressure is clearly one such possible source but its direct local forcing through the `inverse barometer' accounts for only one-third of the observed variability. A number of larger scale atmospheric and ocean processes must also play important roles, but modelling them satisfactorily and separating the individual contributions present a major challenge. As regards future regional UK sea level changes, we conclude that there is no basis for major modification to existing projections for the 2080s included in the 2002 UK Climate Impacts Programme studies.

  12. 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…

  13. 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...

  14. 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.

  15. 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.

  16. Shoreline retreat and sediment release in response to accelerating sea level rise: Measuring and modelling cliffline dynamics on the Suffolk Coast, UK

    NASA Astrophysics Data System (ADS)

    Brooks, S. M.; Spencer, T.

    2012-01-01

    Contemporary and historic data for shoreline retreat are used to evaluate and test a range of models that predict shoreline response to accelerating sea level rise. Models are tested against the known record of sea level rise acceleration over the twentieth century on the cliffline position of a series of soft rock cliffs located along the Suffolk Coast, UK. These cliffs have experienced high retreat rates throughout the twentieth century (between 2 and 4.5 m a - 1 ). The shoreline response model most suited to such an assessment is the SCAPE model, with a close fit between actual and modelled shoreline positions. Retreating shorelines also have associated changes in alongshore elevation, an aspect of shoreline retreat that has attracted little attention. Recently acquired IfSar data now permit detailed and accurate assessment of ground elevation from which the elevation of future clifflines can be derived. Combining elevation data with future shoreline retreat, also predicted using the SCAPE model, enables future sediment release from the cliffs to be evaluated. The methodology has the ability to take into account alongshore variability in retreat rates, where previously most studies focus upon a single rate for a given shoreline. This paper thereby identifies behaviour based around "switching on", "no change" and "switching off" in cliff systems. Volumes of sediment released in the twenty first century in response to accelerating sea level rise are likely to be considerable (up to 300 000 m 3 a - 1 ) for the Suffolk study area, and around an order of magnitude above the sediment release estimates for the early twentieth century under lower rates of sea level rise. The implications for shoreline protection offered from additional sediment in the nearshore zone are discussed.

  17. 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.

  18. 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.

  19. Inconsistencies in sea level pressure trends between different atmospheric products. Impact on sea level trend estimation

    NASA Astrophysics Data System (ADS)

    Gomis, D.; Jordà, G.

    2012-04-01

    Long term climate datasets are of great importance to understand the processes behind climate variability, to evaluate the performance of climate models and to identify signals of climate change. Among the different atmospheric variables, sea level pressure (SLP) is the basic dynamical variable and is the most widely analyzed quantity. From the ocean perspective, SLP is of crucial importance for a dynamical interpretation of sea level records. In order to isolate the contribution to sea level variability of circulation and heat and freshwater contents, a common practice is to remove the sea level fluctuations induced by SLP. At seasonal and longer time scales, sea level is expected to react as an inverted barometer (IB) to changes in SLP. Therefore, provided that accuracy of available SLP data is high enough, the atmospheric contribution to sea level variability can be isolated and removed from sea level records. This is routinely done for tide gauge records, altimetry or sea level reconstructions. Different atmospheric gridded products spanning the last decades are nowadays available. On the one hand, there are historical SLP datasets where observations from land stations and ocean observations have been interpolated into a regular grid. On the other hand, there are reanalyses where an atmospheric model is run assimilating the historical data. Both kind of products have been extensively used in recent years either directly (i.e. to analyse the SLP evolution) or indirectly (i.e. through the removal of IB effect on sea level records). However, it is well known that the quality of those products may not be homogeneous on time. In this contribution, we compare long term SLP trends from different atmospheric products (reanalysis and gridded historical datasets), and evaluate the uncertainties introduced by them in the sea level trend estimations. The results show that discrepancies between datasets can induce an uncertainty up to 0.5 mm/yr for the period 1958-2001 on

  20. Ice sheet systems and sea level change.

    NASA Astrophysics Data System (ADS)

    Rignot, E. J.

    2015-12-01

    Modern views of ice sheets provided by satellites, airborne surveys, in situ data and paleoclimate records while transformative of glaciology have not fundamentally changed concerns about ice sheet stability and collapse that emerged in the 1970's. Motivated by the desire to learn more about ice sheets using new technologies, we stumbled on an unexplored field of science and witnessed surprising changes before realizing that most were coming too fast, soon and large. Ice sheets are integrant part of the Earth system; they interact vigorously with the atmosphere and the oceans, yet most of this interaction is not part of current global climate models. Since we have never witnessed the collapse of a marine ice sheet, observations and exploration remain critical sentinels. At present, these observations suggest that Antarctica and Greenland have been launched into a path of multi-meter sea level rise caused by rapid climate warming. While the current loss of ice sheet mass to the ocean remains a trickle, every mm of sea level change will take centuries of climate reversal to get back, several major marine-terminating sectors have been pushed out of equilibrium, and ice shelves are irremediably being lost. As glaciers retreat from their salty, warm, oceanic margins, they will melt away and retreat slower, but concerns remain about sea level change from vastly marine-based sectors: 2-m sea level equivalent in Greenland and 23-m in Antarctica. Significant changes affect 2/4 marine-based sectors in Greenland - Jakobshavn Isb. and the northeast stream - with Petermann Gl. not far behind. Major changes have affected the Amundsen Sea sector of West Antarctica since the 1980s. Smaller yet significant changes affect the marine-based Wilkes Land sector of East Antarctica, a reminder that not all marine-based ice is in West Antarctica. Major advances in reducing uncertainties in sea level projections will require massive, interdisciplinary efforts that are not currently in place

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Comparisons of various sea level reconstructions and sea level from data synthesis products: 1960-2012

    NASA Astrophysics Data System (ADS)

    Carson, Mark; Stammer, Detlef; Köhl, Armin; Meyssignac, Benoit; Church, John; Schröter, Jens; Wenzel, Manfred

    2016-04-01

    We investigate sea level trends and variability as reconstructed from tide gauge data and ocean data assimilations (ODA) over the last 60 years. Tide gauge reconstructions (TGR) are mostly based on statistical approaches using selected EOFs, or trained from variability patterns, from altimetric sea level and tide gauge data to extrapolate regional sea level evolution backward in time. Reconstructions also exist from dynamical ocean modeling approaches with and without data assimilation. We intercompare all results and provide ensemble mean and ensemble spreads to describe estimates of past regional sea level changes and their uncertainties. While tide gauge reconstructions match tide gauge data better than ODA, they exhibit less variability in the open ocean. TGRs match the trends and variability better during the satellite-altimetry era than for the entire period from 1960-2012, whereas the ODAs mostly do not. An average of all products produces the best statistics for comparing to the set of tide gauges. The results are mixed. The TGRs and ODAs can be useful in some respects, such as calculating a global sea-level signal, and matching altimetric data, and each other, well in the Pacific. But the regional open-ocean sea-level change and variability found from altimetric data are not well reproduced over substantial portions of the ocean. Over periods earlier than the satellite era, these reconstructed regional patterns may not be trustworthy, nor can they be verified.

  7. 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.

  8. 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).

  9. Hurricanes, sea level rise, and coastal change

    USGS Publications Warehouse

    Sallenger,, Asbury H.; Wang, Ping; Rosati, Julie D.; Roberts, Tiffany M.

    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.

  10. 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…

  11. 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.

  12. 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.

  13. 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

  14. 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.

  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

  16. 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

  17. 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.

  18. Attribution of Annual Maximum Sea Levels to Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Khouakhi, A.; Villarini, G.

    2015-12-01

    Tropical cyclones (TCs) can cause catastrophic storm surges with major social, economic, and ecological impacts in coastal areas. Understanding the contribution of TCs to extreme sea levels is therefore essential. In this work we examine the contribution of TCs to annual maximum sea levels at the global scale, including potential climate controls and temporal changes. Complete global coverage (1842-2014) of historical 6-hour best track TC records are obtained from the International Best Track Archive for Climate Stewardship (IBTrACS) data set. Hourly tide gauge data are obtained from the Joint Archive for Sea Level Research Quality Data Set. There are 177 tide gauge stations with at least 25 complete years of data between 1970 and 2014 (a complete year is defined as having more than 90% of all the hourly measurements in a year). We associate an annual maximum sea level at a given station with a TC if the center of circulation of the storm passed within a certain distance from the station within a given time window. Spatial and temporal sensitivity analyses are performed with varying time windows (6h, 12h) and buffer zones (200km and 500km) around the tide gauge stations. Results highlight large regional differences, with some locations experiencing almost ¾ of their annual maxima during the passage of a TC. The attribution of annual maximum sea level to TCs is particularly high along the coastal areas of the eastern United States, the Gulf of Mexico, China, Japan, Taiwan and Western Australia. Further analyses will examine the role played by El Niño - Southern Oscillation and the potential temporal changes in TC contributions to annual maximum sea levels.

  19. Uncertainty estimates of altimetric Global Mean Sea Level timeseries

    NASA Astrophysics Data System (ADS)

    Scharffenberg, Martin; Hemming, Michael; Stammer, Detlef

    2016-04-01

    An attempt is being presented concerned with providing uncertainty measures for global mean sea level time series. For this purpose sea surface height (SSH) fields, simulated by the high resolution STORM/NCEP model for the period 1993 - 2010, were subsampled along altimeter tracks and processed similar to techniques used by five working groups to estimate GMSL. Results suggest that the spatial and temporal resolution have a substantial impact on GMSL estimates. Major impacts can especially result from the interpolation technique or the treatment of SSH outliers and easily lead to artificial temporal variability in the resulting time series.

  20. Occurence of Extreme Sea Level Events In The Coastal Waters of West Estonia, The Baltic Sea

    NASA Astrophysics Data System (ADS)

    Suursaar, Ü.; Kullas, T.; Otsmann, M.; Kõuts, T.

    Extreme low and high sea level events are analysed on the basis of available historical data and mechanisms of surges studied appplying the 1 km grid step 2D hydrodynamic model in the two nearly tideless semienclosed sub-basins of the Baltic Sea, the Gulf of Riga and the Väinameri. Based on the input and verification data from 1999, the water level is modelled with realistic and idealistic forcing schemes. The low level events are associated with the local wind pattern of easterly winds, determined by the corresponding regional air pressure fields above the Central Baltic. The high levels (up to 253 cm above the long-term average as measured in Pärnu) are associated with SW and W storms. They first appear due to the water volume change in the Baltic Sea, then due to an additional volume increase in the Gulf of Riga, and finally due to the local level slope in the narrow and shallow bays. An amplification due to resonance with seiche or Helmholtz oscillation periods is also possible. Simulations showed that the extreme high and low sea levels in some small bays of West Estonia without tide- gauges could exceed the corresponding values in the Pärnu Bay.

  1. Interannual and Interdecadal Variability in Sea Level.

    NASA Astrophysics Data System (ADS)

    Unal, Yurdanur Sezginer

    The observational data set archived by the Permanent Service for Mean Sea Level (PSMSL) consists of monthly means of sea-level heights at 846 stations. 213 of them are suitable for our purposes. We identified two dominant time scales of El Nino-Southern Oscillation (ENSO) signal, as quasi-biennial and low-frequency (LF) at almost all stations, with the highest amplitudes in the equatorial Pacific and along the west coast of North America. Global sea-level rise, after post-glacial rebound corrections, are 1.620.38 mm/yr. Propagation features of the interannual variability are studied along the coastal sea level stations in five regions: eastern, western, and equatorial Pacific; eastern and western Atlantic. Throughout the Pacific, three dominant spatio-temporal oscillatory patterns are found in the time scales of ENSO variability. In the eastern Pacific, the biennial mode and the 6-yr low-frequency mode propagate poleward. In the western Pacific, interannual oscillation propagates southward in the northern hemisphere but no clear propagation is observed in the southern hemisphere. Equatorward propagation of the biennial signal is very clear in each hemisphere. In the equatorial Pacific, both the quasi -quadrannial and quasi-biennial modes at 10^ circN propagate westward. Strong and weak El Nino years are evident in RSLH reconstructed from the biennial and low-frequency modes. Interannual variability with periods of 3 and 4-8 years is detected in the Atlantic RSLH data. In the eastern Atlantic region, we have found slow propagation of both modes northward and southward, away from 40-45^circN. Sufficiently long and continuous RSLH at 81 stations show interdecadal oscillations with the periods of 9-13 and 18 years. 11.6 and 12.8 years of oscillations are found in the eastern and western Atlantic ocean at latitudes 40^circN-70^ circN and 10^circN -50^circN, respectively. The aforementioned features are simulated with a wind driven ocean model for the periods of 1950 and

  2. Saharan dust aerosol over the central Mediterranean Sea: optical columnar measurements vs. aerosol load, chemical composition and marker solubility at ground level

    NASA Astrophysics Data System (ADS)

    Marconi, M.; Sferlazzo, D. M.; Becagli, S.; Bommarito, C.; Calzolai, G.; Chiari, M.; di Sarra, A.; Ghedini, C.; Gómez-Amo, J. L.; Lucarelli, F.; Meloni, D.; Monteleone, F.; Nava, S.; Pace, G.; Piacentino, S.; Rugi, F.; Severi, M.; Traversi, R.; Udisti, R.

    2013-08-01

    This study aims at the determination of the mineral contribution to PM10 in the central Mediterranean Sea on the basis of 7 yr of PM10 chemical composition daily measurements made on the island of Lampedusa (35.5° N, 12.6° E). Aerosol optical depth measurements are carried out in parallel while sampling with a multi-stage impactor, and observations with an optical particle counter were performed in selected periods. Based on daily samples, the total content and soluble fraction of selected metals are used to identify and characterize the dust events. The total contribution is determined by PIXE (particle-induced X-ray emission) while the composition of the soluble fraction by ICP-AES (inductively coupled plasma atomic emission spectroscopy) after extraction with HNO3 at pH 1.5. The average PM10 concentration at Lampedusa calculated over the period June 2004-December 2010 is 31.5 μg m-3, with low interannual variability. The annual means are below the EU annual standard for PM10, but 9.9% of the total number of daily data exceed the daily threshold value established by the European Commission for PM (50 μg m-3, European Community, EC/30/1999). The Saharan dust contribution to PM10 was derived by calculating the contribution of Al, Si, Fe, Ti, non-sea-salt (nss) Ca, nssNa, and nssK oxides in samples in which PIXE data were available. Cases with crustal content exceeding the 75th percentile of the crustal oxide content distribution were identified as dust events. Using this threshold we identify 175 events; 31.6% of them (55 events) present PM10 higher than 50 μg m-3, with dust contributing by 33% on average. The annual average crustal contribution to PM10 is 5.42 μg m-3, reaching a value as high as 67.9 μg m-3, 49% of PM10, during an intense Saharan dust event. The crustal aerosol amount and contribution to PM10 shows a very small seasonal dependence; conversely, the dust columnar burden displays an evident annual cycle, with a strong summer maximum (monthly

  3. 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

  4. Storminess helps coastal marshes withstand sea level rise

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-03-01

    Rising sea levels are predicted to threaten many coastal sea marshes around the world in the coming decades as the Earth's climate warms. In addition to accelerating sea level rise, global climate change is predicted to increase the frequency and severity of storms in many places around the world. However, few studies have taken into account how an increased storminess might affect the ability of coastal marshes to withstand sea level rise.

  5. Investigating the influence of sea level oscillations in the Danish Straits on the Baltic Sea dynamics

    NASA Astrophysics Data System (ADS)

    Tikhonova, Natalia; Gusev, Anatoly; Diansky, Nikolay; Zakharchuk, Evgeny

    2016-04-01

    related to the distance between the measurement point and open boundary. For example, in the Gulfs of Finland and Riga, the 36hr harmonic has an amplitude substantially higher than in the open sea, and in the Stockholm area, this harmonic is at the noise level. The 40dy and 121dy harmonics have slightly lower amplitudes than the original prescribed signal, but they are almost unchanged while propagating further into the sea, and in all the investigated locations have almost identical peaks of spectral density. The 3dy and 6dy harmonics significantly lost their amplitude in all parts of the sea, and spectral density peaks are at the noise level. The simulation results showed us that the Danish straits do not filter 121dy and 40dy oscillations, and their amplitude does not decrease much. The 13dy, 6dy and 3dy oscillations significantly lose in amplitude and have no significant peaks of the spectral density. The 1.5dy harmonic propagates to the Gulfs of Finland and Riga, and increases in amplitude due to resonance at the natural frequency of the basin. It is suggested that, while Danish straits do not filter or transform frequency characteristics of oscillations propagated from the North Sea, but the Baltic Sea configuration may affect the magnitude and propagation extent of these oscillations. Thus, the fluctuations in the North Sea and the Danish Straits can significantly contribute to the Baltic Sea dynamics in the low-frequency range of the spectrum, and the periods of natural oscillations of the basin. The research was supported by the Russian Foundation for Basic Research (grant № 16-05-00534) and Saint-Petersburg State University (grant №18.37.140.2014)

  6. 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

    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.

  7. 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.

  8. 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.

  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. 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

  12. Mean Tide Level Data in the PSMSL Mean Sea Level Dataset

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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), is a regular member of the ICSU World Data System and is associated with 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 holds over 67,000 station-years of monthly and annual mean sea level data from over 2250 tide gauge stations. Data from each site are quality controlled and, wherever possible, reduced to a common datum, whose stability is monitored through a network of geodetic benchmarks. PSMSL also distributes a data bank of measurements taken from in-situ ocean bottom pressure recorders. Most of the records in the main PSMSL dataset indicate mean sea level (MSL), derived from high-frequency tide gauge data, with sampling typically once per hour or higher. However, some of the older data is based on mean tide level (MTL), which is obtained from measurements taken at high and low tide only. While usually very close, MSL and MTL can occasionally differ by many centimetres, particularly in shallow water locations. As a result, care must be taken when using long sea level records that contain periods of MTL data. Previously, periods during which the values indicated MTL rather than MSL were noted in the documentation, and sometimes suggested corrections were supplied. However, these comments were easy to miss, particularly in large scale studies that used multiple stations from across

  13. Salt marsh stability modelled in relation to sea level rise

    NASA Astrophysics Data System (ADS)

    Bartholdy, Jesper; Bartholdy, Anders T.; Kroon, Aart

    2010-05-01

    Accretion on a natural backbarrier salt marsh was modeled as a function of high tide level, initial salt marsh level and distance to the source. Calibration of the model was based on up to ca 80 year old marker horizons, supplemented by 210Pb/137Cs datings and subsequent measurements of clay thickness. Autocompaction was incorporated in the model, and shown to play a major role for the translation of accretion rates measured as length per unit time to accumulation rates measured as mass per area per unit time. This is important, even for shallow salt marsh deposits for which it is demonstrated that mass depth down core can be directly related to the bulk dry density of the surface layer by means of a logarithmic function. The results allow for an evaluation of the use of marker horizons in the topmost layers and show that it is important to know the level of the marker in relation to the salt marsh base. In general, deeper located markers will indicate successively smaller accretion rates with the same sediment input. Thus, stability analysis made on the basis of newly established marker horizons will be biased and indicate salt marsh stabilities far above the correct level. Running the model with a constant sea level revealed that balance between the inner and the outer salt marsh deposition can not be achieved within a reasonable time scale. Likewise it is shown that only one specific sea level rise provides equilibrium for a given location on the salt marsh. With a higher sea level rise, the marsh at the specific location will eventually drown, whereas - with a sea level rise below this level - it will grow towards the top of the rising tidal frame. The short term variation of salt marsh accretion was found to correlate well with variations in the North Atlantic Oscillation - the NAO winter index. Comparisons between the geomorphological development of wind tide affected salt marshes, like those present on the Danish North Sea coasts, and primary astronomically

  14. On how climate variability influences regional sea level change

    NASA Astrophysics Data System (ADS)

    Brunnabend, Sandra-Esther; Kusche, Jürgen; Rietbroek, Roelof; Forootan, Ehsan

    2016-04-01

    Regional trends in sea level change are strongly influenced by climate variations, such as ENSO (El-Nino Southern Oscillation), the IOD (Indian Ocean Dipole), or the PDO (Pacific Decadal Oscillation). Hence, before computing long term regional sea level change, these sea level variations need to be taken into account as they lead to strong dependencies of computed regional sea level trends on the time period of the investigation. In this study, sea level change during the years 1993 to 2013 is analysed to identify the dominant modes of sea level change caused by climate variations. Here, two different gridded altimetry products are analysed, namely ESA's combined CCI SeaLevel v1.1 ECV product (doi: 10.5270/esa-sea_level_cci-1993_2013-v_1.1-201412), and absolute dynamic topography produced by Ssalto/Duacs and distributed by Aviso, with support from Cnes (http://www.aviso.altimetry.fr/duacs/). Reconstructions using the different decomposition techniques including the standard principle component analysis (PCA), rotated empirical orthogonal functions (REOF) and independent component analysis (ICA) method are analysed. They are compared with sea level change modelled with the global finite-element sea-ice ocean model (FESOM). The results indicate that from the applied methods, ICA is most suitable to separate the individual climate variability signals in independent modes of sea level change. This especially holds for extracting the ENSO contribution in sea level changes, which was better separated by applying ICA, from both altimetry and modelled sea level products. In addition, it is presented how modelled sea level change reflects climate variations compared to that identified in the altimetry products.

  15. 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

  16. Closing the Global Sea Level Rise Budget with GRACE, Argo, and Altimetry Observations

    NASA Astrophysics Data System (ADS)

    Leuliette, E. W.; Miller, L.

    2008-12-01

    An important goal of climate studies is to determine the relative contribution of steric (heating and salinty) and eustatic (melting ice, runoff) sea level rise and to understand how and why these contributions vary. Concurrent measurements from the Argo array of profiling floats and the GRACE gravity mission, which respectively measure steric and eustatic changes, provide an independent measure of total sea level change. An analysis of the steric and ocean mass components of sea level shows that the sea level rise budget for the period January 2004 to December 2007 can be closed. Using corrected and verified Jason-1 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, we find that the sum of steric sea level and the ocean mass component has a trend of 1.5 ± 1.5 mm/year over the period, in agreement with the total sea level rise observed by either Jason-1 (2.2 ± 1.6 mm/year) or Envisat (1.7 ± 1.8 mm/year). This provides verification that the altimeters, Argo buoys, and GRACE are providing consistent results and opens the way to routine monitoring of the major components of sea level rise.

  17. Sea level trends for all sections of the Baltic Sea coastline

    NASA Astrophysics Data System (ADS)

    Madsen, Kristine S.; Høyer, Jacob L.; Suursaar, Ülo; Knudsen, Per; She, Jun

    2016-04-01

    To better understand influence of sea level rise on societal vulnerability and coastal erosion processes, it is important to know the sea level trend. The coastline of the Baltic Sea is not uniformly exposed, and therefore we will determine the sea level trend of the last 10, 50 and 100 years for all sections of the coastline. The observational record of sea level in the Baltic Sea is quite unique with several records of more than 100 years of data. However, the information is confined to the tide gauge locations. Here, we utilize a statistical method based on least squares regression and originally developed for short term sea level variability (Madsen et al. 2015, JGR, doi:10.1002/2015JC011070) to spread out the sea level information from selected tide gauges to all sections of the Baltic Sea coast. Monthly mean tide gauge observations are retrieved from PSMSL and supplemented with Estonian observations. The spatial distribution of the sea level is obtained from model reanalysis from the Copernicus Marine Service and satellite altimetry observations and land rise information is taken into account. Results are validated against independent tide gauges, providing a consistent record of 20th century sea level trends and variability, including uncertainties, for the entire Baltic Sea coastline. This work is sponsored by the EMODnet project Baltic Checkpoint.

  18. Anthropometric Measures of 9- to 10-Year-Old Native Tibetan Children Living at 3700 and 4300 m Above Sea Level and Han Chinese Living at 3700 m.

    PubMed

    Bianba, Bianba; Yangzong, Yangzong; Gonggalanzi, Gonggalanzi; Berntsen, Sveinung; Andersen, Lars Bo; Stigum, Hein; Nafstad, Per; Bjertness, Espen

    2015-10-01

    A high residential altitude impacts on the growth of children, and it has been suggested that linear growth (height) is more affected than body mass. The aim of the present study was to estimate the prevalence of obesity, overweight, underweight, and stunting in groups of native Tibetan children living at different residential altitudes (3700 vs 4300 m above sea level) and across ancestry (native Tibetan vs Han Chinese children living at the same altitude of 3700 m), as well as to examine the total effect of residential altitude and ancestry with stunting.Two cross-sectional studies of 1207 school children aged 9 to 10 years were conducted in Lhasa in 2005 and Tingri in 2007. Conventional age- and sex-specific cutoff values were used for defining underweight, normal weight, overweight, or obesity, whereas stunting was defined from sex-specific height-for-age z-scores (≤-2.0).The prevalence of underweight was high at 36.7% among Tingri Tibetan girls and 31.1% in Tingri Tibetan boys. The prevalence was statistically significant lower in Lhasa Tibetan girls (20.2%) than in both Tingri Tibetan girls and Han Chinese girls (33.7%), with a similar trend seen among boys. Severe and moderate stunting were found in 14.6% and 35.7%, respectively, of Tingri children, and near null among Han Chinese and native Tibetans in Lhasa. In logistic regression analyses, socioeconomic status and diet did not substantially change the observed crude association (total effect) (odds ratio [OR] = 3.3; 95% confidence interval [CI] 1.1-10.3) between ancestry and stunting. Similarly, adjustment for diet did not alter the crude association (direct effect) (OR = 101.3; 95% CI 37.1-276.4) between residential altitude and stunting.The prevalence estimates of stunting and underweight were high, and clearly higher among native Tibetan children living at a higher residential altitude (Tingri) than the lower residential altitude (Lhasa), in addition to being higher among Han Chinese children than

  19. 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

  20. 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.

  1. NASA Now: Climate Change: Sea Level Rise

    NASA Video Gallery

    Dr. Josh Willis discusses the connection between oceans and global climate change. Learn why NASA measures greenhouse gases and how we detect ocean levels from space. These are crucial vital signs ...

  2. Geodetic observation of sea-level change and crustal deformation in the Baltic Sea region

    NASA Astrophysics Data System (ADS)

    Richter, A.; Groh, A.; Dietrich, R.

    Based on tide gauge observations spanning almost 200 years, homogeneous time series of the mean relative sea level were derived for nine sites at the southern coast of the Baltic Sea. Our regionally concentrated data were complemented by long-term relative sea-level records retrieved from the data base of the Permanent Service for Mean Sea Level (PSMSL). From these records relative sea-level change rates were derived at 51 tide gauge stations for the period between 1908 and 2007. A minimum observation time of 60 years is required for the determination of reliable sea-level rates. At present, no anthropogenic acceleration in sea-level rise is detected in the tide gauge observations in the southern Baltic. The spatial variation of the relative sea-level rates reflects the fingerprint of GIA-induced crustal uplift. Time series of extreme sea levels were also inferred from the tide gauge records. They were complemented by water level information from historic storm surge marks preserved along the German Baltic coast. Based on this combined dataset the incidence and spatial variation of extreme sea levels induced by storm surges were analysed yielding important information for hazard assessments. Permanent GPS observations were used to determine recent crustal deformation rates for 44 stations in the Baltic Sea region. The GPS derived height change rates were applied to reduce the relative sea-level changes observed by tide gauges yielding an estimate for the eustatic sea-level change. For 13 tide gauge-GPS colocation sites a mean eustatic sea-level trend of 1.3 mm/a was derived for the last 100 years.

  3. 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.

  4. Sea-level line extraction based on piecewise line detection

    NASA Astrophysics Data System (ADS)

    Lei, Bo; Ren, Tingting; Liu, Yingbin; Yu, Jianwei

    2014-11-01

    In infrared image, sea-level line could be hard to distinguish because of noises caused by wave clutters and sunlight conditions.This paper proposed a fast sea-level line extraction method which could localize the sea-level line in complex infrared sea-sky scenes. First, a down sample operation was performed to obtain a low resolution image which could reduce the time consumption without blurring the sea-level line, and then the Canny edge detection was carried out to extract edges in the scene. Second, the intersecting edges were separated by removing the joints of edges according to a certain rule, and the bounding rectangle of every short edge was obtained which helped to select straight lines, and then a long edge segmentation operation was used to count in possible sea-level line. Third, a line concatenation method was performed by their slopes and intercepts comparison. Finally, for sea-level line verification, the second-order vertical grads are calculated in the two sides of possible sea-level line. Experiments show that the proposed method is fast and effective for various kinds of infrared sea-sky scenes, and it is feasible even for the scenes where the sea-level line is blurring and hard to distinguish.

  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. 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.

  7. 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

    2014-04-14

    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.

  8. 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

  9. 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

  10. Recent Global Sea Level Acceleration Started Over 200 Years Ago?

    NASA Astrophysics Data System (ADS)

    Jevrejeva, S.; Moore, J.; Grinsted, A.; Woodworth, P.

    2008-12-01

    We present a reconstruction of global sea level (GSL) since 1700 calculated from tide gauge records and analyse the evolution of global sea level acceleration during the past 300 years. We provide observational evidence that sea level acceleration up to the present has been about 0.01 mm/yr2 and appears to have started at the end of the 18th century. Sea level rose by 6 cm during the 19th century and 19 cm in the 20th century. Superimposed on the long-term acceleration are quasi-periodic fluctuations with a period of about 60 years. If the conditions that established the acceleration continue, then sea level will rise 34 cm over the 21st century. Long time constants in oceanic heat content and increased ice sheet melting imply that the latest Intergovernmental Panel on Climate Change (IPCC) estimates of sea level are probably too low.

  11. 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.

  12. Probabilistic surface reconstruction of relative sea-level rise

    NASA Astrophysics Data System (ADS)

    Choblet, Gael; Husson, Laurent; Bodin, Thomas; Capdeville, Yann

    2013-04-01

    Relative sea level is shaped by multiple processes (mantle dynamic topography, plate tectonics, glacio-isostatic adjustment, present day melting of continental ice, anthropogenic causes…), most of which induce spatial gradients in relative sea level fluctuations. The evaluation of the global mean sea level rise is a also a key variable to decipher sea level evolution. Tide gauges represent the only mean to monitor sea-level rise on the scale of the 20th century, while the high quality satellite altimetry era is too short to be immune from short-term fluctuations. Tide gauge data compiled by the Permanent Service for the Mean Sea Level (PSMSL) converts into local estimates of sea level rise. Classically, these in situ observations are averaged spatially in order to infer the global mean sea level trend. However, the strongly heterogeneous distribution of tide gauges (e.g. very sparse in the Southern hemisphere) makes this approach relatively prone to uncertainties, given that sea level rise strongly varies geographically. Last, the societal consequences for coastal communities raise the prominent need for local (rather than global) sea level estimates. An alternative is therefore to provide a global surface reconstruction of relative sea level leading to both local variations and a better constrained global average. Here, we propose such a model from tide gauge records using a probabilistic scheme based on the reversible jump Markov chain Monte Carlo algorithm (as described by Bodin et al., JGR, 2012 for the example of the Australian Moho). This method allows to infer both model and parameter space so that not only the functions within the model but also the number of functions itself are free to vary. This is particulalry relevant to the case of tide gauges that are unevenly distributed on the surface of the Earth and whose record lengths are strongly variable. In addition, Bayesian statistics leads to a probabilistic representation (rather than a best fitting

  13. Background neutron spectrum at 2420 m above sea level

    NASA Astrophysics Data System (ADS)

    Vega-Carrillo, Hector Rene; Manzanares-Acuña, Eduardo

    2004-05-01

    The ambient neutron spectrum was measured in-doors at ground level in Zacatecas Mexico at 2420 m above sea level. A Bonner sphere spectrometer with a 6LiI(Eu) scintillator was used to obtain the neutron spectrum. With the spectrum the ambient dose equivalent was calculated using the ICRP 74 neutron fluence-to-dose conversion factors. The neutron fluence rate was 65±3 cm -2 h -1, producing 13.7±0.6 nSv h -1 due to ambient dose equivalent.

  14. 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.

  15. 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

  16. Sea-level rise and its impact on coastal zones.

    PubMed

    Nicholls, Robert J; Cazenave, Anny

    2010-06-18

    Global sea levels have risen through the 20th century. These rises will almost certainly accelerate through the 21st century and beyond because of global warming, but their magnitude remains uncertain. Key uncertainties include the possible role of the Greenland and West Antarctic ice sheets and the amplitude of regional changes in sea level. In many areas, nonclimatic components of relative sea-level change (mainly subsidence) can also be locally appreciable. Although the impacts of sea-level rise are potentially large, the application and success of adaptation are large uncertainties that require more assessment and consideration.

  17. 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.

  18. 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.

  19. 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.

  20. Pacific Sea Level Rise Pattern and Global Warming Hiatus

    NASA Astrophysics Data System (ADS)

    Peyser, C.; Yin, J.; Landerer, F. W.

    2015-12-01

    We investigate the linkage between two notable features of climate change and sea level rise during the past decades: a slowdown in global warming (hiatus) and an east-west seesaw pattern of SLR in the Pacific. During the hiatus, the subsurface layer of the Pacific shows significant increase in ocean heat content along with a strong east-west gradient that is reflected in the seesaw pattern of Pacific SLR through the thermosteric effect. Control simulations from 38 climate models indicate that during periods of negative trend in global mean surface temperature (analogous to hiatus decades in a warming world), dynamic sea level increases in the western Pacific and decreases in the eastern Pacific. The opposite occurs during periods of positive temperature trends. Using a regression analysis of the model simulations along with sea-level measurements from satellite altimetry, we find that the recent change in the Pacific Ocean heat storage has suppressed potential surface warming since 1998. Our results suggest that a flip of the Pacific SLR seesaw would imply a resumption of surface warming and SLR acceleration along the U.S. West Coast.

  1. 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. *

  2. 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

  3. Detecting anthropogenic footprints in sea level rise

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  4. 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.

  5. 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

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

    NASA Technical Reports Server (NTRS)

    2008-01-01

    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.

  7. 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.

  8. Impact of sea-level rise on sea water intrusion in coastal aquifers.

    PubMed

    Werner, Adrian D; Simmons, Craig T

    2009-01-01

    Despite its purported importance, previous studies of the influence of sea-level rise on coastal aquifers have focused on specific sites, and a generalized systematic analysis of the general case of the sea water intrusion response to sea-level rise has not been reported. In this study, a simple conceptual framework is used to provide a first-order assessment of sea water intrusion changes in coastal unconfined aquifers in response to sea-level rise. Two conceptual models are tested: (1) flux-controlled systems, in which ground water discharge to the sea is persistent despite changes in sea level, and (2) head-controlled systems, whereby ground water abstractions or surface features maintain the head condition in the aquifer despite sea-level changes. The conceptualization assumes steady-state conditions, a sharp interface sea water-fresh water transition zone, homogeneous and isotropic aquifer properties, and constant recharge. In the case of constant flux conditions, the upper limit for sea water intrusion due to sea-level rise (up to 1.5 m is tested) is no greater than 50 m for typical values of recharge, hydraulic conductivity, and aquifer depth. This is in striking contrast to the constant head cases, in which the magnitude of salt water toe migration is on the order of hundreds of meters to several kilometers for the same sea-level rise. This study has highlighted the importance of inland boundary conditions on the sea-level rise impact. It identifies combinations of hydrogeologic parameters that control whether large or small salt water toe migration will occur for any given change in a hydrogeologic variable.

  9. Impact of sea-level rise on sea water intrusion in coastal aquifers.

    PubMed

    Werner, Adrian D; Simmons, Craig T

    2009-01-01

    Despite its purported importance, previous studies of the influence of sea-level rise on coastal aquifers have focused on specific sites, and a generalized systematic analysis of the general case of the sea water intrusion response to sea-level rise has not been reported. In this study, a simple conceptual framework is used to provide a first-order assessment of sea water intrusion changes in coastal unconfined aquifers in response to sea-level rise. Two conceptual models are tested: (1) flux-controlled systems, in which ground water discharge to the sea is persistent despite changes in sea level, and (2) head-controlled systems, whereby ground water abstractions or surface features maintain the head condition in the aquifer despite sea-level changes. The conceptualization assumes steady-state conditions, a sharp interface sea water-fresh water transition zone, homogeneous and isotropic aquifer properties, and constant recharge. In the case of constant flux conditions, the upper limit for sea water intrusion due to sea-level rise (up to 1.5 m is tested) is no greater than 50 m for typical values of recharge, hydraulic conductivity, and aquifer depth. This is in striking contrast to the constant head cases, in which the magnitude of salt water toe migration is on the order of hundreds of meters to several kilometers for the same sea-level rise. This study has highlighted the importance of inland boundary conditions on the sea-level rise impact. It identifies combinations of hydrogeologic parameters that control whether large or small salt water toe migration will occur for any given change in a hydrogeologic variable. PMID:19191886

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

    NASA Astrophysics Data System (ADS)

    Bonaduce, Antonio; Pinardi, Nadia; Oddo, Paolo; Spada, Giorgio; Larnicol, Gilles

    2016-04-01

    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 yr-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 (EEMD) 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.

  11. Deglacial sea-level history of the Sunda Shelf region, South China Sea

    NASA Astrophysics Data System (ADS)

    Stattegger, K.; Tjallingii, R. H.

    2011-12-01

    A unique relative sea-level record of intertidal deposits from incised valley infill was retrieved from the paleo-Mekong and the paleo-North Sunda rivers in the southwestern South China Sea. This flooding history from the Sunda-Shelf system is presently the only sea-level record recovered from siliciclastic coastal deposits that covers the complete deglacial sea-level history of the last 20000 years. Three meltwater pulses (MWP) mark periods of highly accelerated sea-level rise in comparison to the average rate of 0.93 cm/yr. Initial MWP 0 (19400 - 18700 cal yr BP) was the first step of deglacial sea-level rise with a rate of 1.57 cm/yr. MWP 1A (14800 - 14200 cal yr BP), and MWP 1C (8800 - 8200 cal yr BP) have highly accelerated rates up to 5 cm/yr, whereas there is no evidence of MWP 1B around 11300 cal yr BP. Sea-level rise decreased sharply after 8200 cal yr BP when sea level stood at -7 m and modern shorelines evolved. Mid-Holocene highstand above +1.4 m was reached between 6400 and 5200 cal yr BP with a peak value of +1.5 m. These results improve the present perception of eustatic deglacial sea-level rise. The relative contributions of ice melt from the northern hemisphere and Antarctic ice sheets providing the huge water-volumes of MWPs need to be clarified.

  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. 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.

  15. 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

  16. 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.

  17. Sea-level Variation Along the Suez Canal

    NASA Astrophysics Data System (ADS)

    Eid, F. M.; Sharaf El-Din, S. H.; Alam El-Din, K. A.

    1997-05-01

    The variation of sea level at 11 stations distributed along the Suez Canal was studied during the period from 1980 to 1986. The ranges of variation in daily mean sea level at Port Said and Port Tawfik are about 60 and 120 cm, respectively. The minimum range of daily variation is at Kantara (47 cm). The fluctuations of the monthly mean sea level between the two ends of the Suez Canal vary from one season to another. From July to December, the sea level at Port Said is higher than that at Port Tawfik, with the maximum difference (10·5 cm) in September. During the rest of the year, the mean sea level at Port Tawfik is higher than that at Port Said, with the maximum difference (31·5 cm) in March. The long-term variations of the annual mean sea level at both Port Said and Port Tawfik for the period from 1923 to 1986 showed a positive trend. The sea level at Port Said increased by about 27·8 cm century -1while it increased by only 9·1 cm century -1at Port Tawfik. This indicates that the difference between sea level at Port Said and Port Tawfik has decreased with time.

  18. 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.

  19. Glacial Isostatic Adjustment and Contemporary Sea Level Rise: An Overview

    NASA Astrophysics Data System (ADS)

    Spada, Giorgio

    2016-08-01

    Glacial isostatic adjustment (GIA) encompasses a suite of geophysical phenomena accompanying the waxing and waning of continental-scale ice sheets. These involve the solid Earth, the oceans and the cryosphere both on short (decade to century) and on long (millennia) timescales. In the framework of contemporary sea-level change, the role of GIA is particular. In fact, among the processes significantly contributing to contemporary sea-level change, GIA is the only one for which deformational, gravitational and rotational effects are simultaneously operating, and for which the rheology of the solid Earth is essential. Here, I review the basic elements of the GIA theory, emphasizing the connections with current sea-level changes observed by tide gauges and altimetry. This purpose is met discussing the nature of the "sea-level equation" (SLE), which represents the basis for modeling the sea-level variations of glacial isostatic origin, also giving access to a full set of geodetic variations associated with GIA. Here, the SLE is employed to characterize the remarkable geographical variability of the GIA-induced sea-level variations, which are often expressed in terms of "fingerprints". Using harmonic analysis, the spatial variability of the GIA fingerprints is compared to that of other components of contemporary sea-level change. In closing, some attention is devoted to the importance of the "GIA corrections" in the context of modern sea-level observations, based on tide gauges or satellite altimeters.

  20. 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.

  1. Regional Long-Term Sea Level and Sea Surface Temperature Characteristics from Satellite Observations

    NASA Astrophysics Data System (ADS)

    Andersen, O. B.; Knudsen, P.; Beckley, B.

    2006-07-01

    For a the large portion of the world's population liv ing in coastal zones forecasts of long- term sea lev el change is importan t for a var iety of environmen tal and socio- economic r easons. Satellite altimetry offers a unique opportunity for improving our knowledge about glob al and r egional sea level change on bo th global and reg ional scale. Joint TOPEX/PO SEIDON(T/P) +JASON-1 sea level observations and Reyno lds AVH RR sea surface temperature observ ations over th e most recen t 12 years hav e qualitativ ely been used to study regional correlations between long-term changes in sea level and sea surface temper ature. Long-term is here tak en to be lin ear signals in the 12-year time per iod Consistent in creases in both sea level and sea surface temp eratures ar e found in large parts of the world's oceans over this per iod. In the Indian Ocean and particularly th e Pacif ic Ocean , the trends in both sea level and temper ature are domin ated by the larg e changes associated w ith th e El N iño Southern Oscillation (ENSO) . Co mparison with similar trend estimates u sing only 8 years of satellite data shows the incr eased decoupling with ENSO and th e imp act of inter-annual variability on sea lev el tr end estimates.

  2. 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].

  3. Comprehensive Measurements of Wind Systems at the Dead Sea

    NASA Astrophysics Data System (ADS)

    Metzger, Jutta; Corsmeier, Ulrich; Kalthoff, Norbert; Wieser, Andreas; Alpert, Pinhas; Lati, Joseph

    2016-04-01

    The Dead Sea is a unique place on earth. It is located at the lowest point of the Jordan Rift valley and its water level is currently at -429 m above mean sea level (amsl). To the West the Judean Mountains (up to 1000 m amsl) and to the East the Moab mountains (up to 1300 m amsl) confine the north-south oriented valley. The whole region is located in a transition zone of semi-arid to arid climate conditions and together with the steep orography, this forms a quite complex and unique environment. The Virtual Institute DEad SEa Research Venue (DESERVE) is an international project funded by the German Helmholtz Association and was established to study coupled atmospheric, hydrological, and lithospheric processes in the changing environment of the Dead Sea. Previous studies showed that the valley's atmosphere is often governed by periodic wind systems (Bitan, 1974), but most of the studies were limited to ground measurements and could therefore not resolve the three dimensional development and evolution of these wind systems. Performed airborne measurements found three distinct layers above the Dead Sea (Levin, 2005). Two layers are directly affected by the Dead Sea and the third is the commonly observed marine boundary layer over Israel. In the framework of DESERVE a field campaign with the mobile observatory KITcube was conducted to study the three dimensional structure of atmospheric processes at the Dead Sea in 2014. The combination of several in-situ and remote sensing instruments allows temporally and spatially high-resolution measurements in an atmospheric volume of about 10x10x10 km3. With this data set, the development and evolution of typical local wind systems, as well as the impact of regional scale wind conditions on the valley's atmosphere could be analyzed. The frequent development of a nocturnal drainage flow with wind velocities of over 10 m s-1, the typical lake breeze during the day, its onset and vertical extension as well as strong downslope winds

  4. Comprehensive Measurements of Wind Systems at the Dead Sea

    NASA Astrophysics Data System (ADS)

    Metzger, Jutta; Corsmeier, Ulrich; Kalthoff, Norbert; Wieser, Andreas; Alpert, Pinhas; Lati, Joseph

    2016-04-01

    The Dead Sea is a unique place on earth. It is located at the lowest point of the Jordan Rift valley and its water level is currently at -429 m above mean sea level (amsl). To the West the Judean Mountains (up to 1000 m amsl) and to the East the Moab mountains (up to 1300 m amsl) confine the north-south oriented valley. The whole region is located in a transition zone of semi-arid to arid climate conditions and together with the steep orography, this forms a quite complex and unique environment. The Virtual Institute DEad SEa Research Venue (DESERVE) is an international project funded by the German Helmholtz Association and was established to study coupled atmospheric, hydrological, and lithospheric processes in the changing environment of the Dead Sea. Previous studies showed that the valley's atmosphere is often governed by periodic wind systems (Bitan, 1974), but most of the studies were limited to ground measurements and could therefore not resolve the three dimensional development and evolution of these wind systems. Performed airborne measurements found three distinct layers above the Dead Sea (Levin, 2005). Two layers are directly affected by the Dead Sea and the third is the commonly observed marine boundary layer over Israel. In the framework of DESERVE a field campaign with the mobile observatory KITcube was conducted to study the three dimensional structure of atmospheric processes at the Dead Sea in 2014. The combination of several in-situ and remote sensing instruments allows temporally and spatially high-resolution measurements in an atmospheric volume of about 10x10x10 km3. With this data set, the development and evolution of typical local wind systems, as well as the impact of regional scale wind conditions on the valley's atmosphere could be analyzed. The frequent development of a nocturnal drainage flow with wind velocities of over 10 m s‑1, the typical lake breeze during the day, its onset and vertical extension as well as strong downslope

  5. 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.

  6. Time Scale Dependent SGD due to the Sea Level Change

    NASA Astrophysics Data System (ADS)

    Lee, K.; Lee, E.; Hyun, Y.

    2009-12-01

    Submarine groundwater discharge (SGD) is defined as the groundwater outflux across the ocean-land interface. In this study, the variation of amount of SGD due to the sea level change is investigated by means of numerical simulation. Numerical code FEFLOW (Diersh et al., 2005) is used to conduct the simulation and the effect of sea level change on the variation of SGD with different time scales from diurnal cycle to glacial cycle is evaluated. The simulation results indicate that generally, the increase of amplitude of sea level leads to the increase of SGD while the increase of period of sea level change cause more complicated pattern of the variation of SGD. These variations are changed with the aquifer properties, especially, hydraulic conductivity. The simulation results show that the sea level change with different period and amplitude leads to the variation of total SGD and it may explain the unknown source of the unexpectedly high amount of SGD.

  7. Sea level data and techniques for detecting vertical crustal movements

    NASA Technical Reports Server (NTRS)

    Lennon, G. W.

    1978-01-01

    An attempt is made to survey problems, requirements, and the outlook for the future in the study of sea level time series so as to determine the relative movement of land and sea levels. The basic aim is to eliminate from the record the contributions from whatever marine dynamic phenomena respond to treatment, allowing the secular element to be identified with optimum clarity. Nevertheless the concept of sea level perturbation varies according to regional experience. The recent work of the Permanent Service for Mean Sea Level helps to eliminate geodetic noise from the series and makes it possible, perhaps, to treat the global mean sea level data bank so as to define eustatic changes in ocean volume which, in the present context, may be regarded as the final goal, allowing the identification of vertical crustal motion itself.

  8. 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.

  9. The Impact of Groundwater Depletion on Spatial Variations in Sea Level Change During the Past Century

    NASA Astrophysics Data System (ADS)

    Conrad, C. P.; Veit, E.; Natarov, S.

    2015-12-01

    The loss of continental groundwater to the oceans during the past century has elevated sea level by ~25(±5) mm, and has caused ~0.7mm/yr of sea level rise since 2005. The mass unloading associated with this groundwater depletion induces elastic uplift of Earth's solid surface and depresses the gravitational equipotential surface that defines sea level. Together, these deflections should cause slower relative sea level rise near areas of continental groundwater loss. We estimated these variations in sea level change using a model of the solid Earth's response to estimates of groundwater depletion during the past century. We find large negative deviations in relative sea level near California, Western India, the western Yellow Sea and the eastern Mediterranean Sea. Relative sea level measured by tide gauges in these areas show slower sea level rise rates compared to global averages. For example, on the western coast of India (e.g., Karachi), groundwater-induced deviations from global average sea level rise can exceed -40 mm, and our model predicts ~1 mm/yr of sea level drop since 2005. Correcting tide gauge records for groundwater depletion using our model improves their fit to the global trend estimated by Church & White (2011), and further reduces the variation of rise rates observed among regional groups of stations. We reconstructed Global Mean Sea Level (GMSL) between 1930 and 2009 taking in account groundwater depletion corrections determined from our model. We found that including groundwater depletion increases our estimate of the global rate of change of GMSL from 1.81 to 1.88 mm/yr during this time period because the observed rise at some key stations is slowed by nearby groundwater depletion. For the past 20 years, including groundwater depletion increases GMSL from 3.32mm/yr to 3.46mm/yr. Quantifying the spatial variability of sea level associated with groundwater depletion is important for understanding the variety of factors that affect sea level, and

  10. 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.

  11. Regional and Global Mean Sea Level Variability Over the Modern Instrumental Record

    NASA Astrophysics Data System (ADS)

    Ponte, R. M.; Wunsch, C.; Heimbach, P.

    2008-12-01

    The possibility of sea level rise in the context of global climate change has received much attention in recent years. Determination of sea level rise and its causes, either globally or regionally, must however cope with other signals in the sea level record. A comprehensive look at sea level variability over the modern instrumental period (1992-present) is made possible by the 3-dimensional, time-dependent ocean state estimates produced under ECCO-GODAE. Such estimates involve a least-squares optimization that produces a "best" fit of the MITgcm to most available ocean data, including several altimetric missions and all in-situ hydrography. The estimated regional sea level patterns exhibit interannual and longer period variability that can easily mask expected long-term trends in mean sea level. Both steric and mass changes contribute to sea level change at regional and global levels, and thermal and haline effects are evident over the full water column, stressing the need for surface-to-bottom measurements. Spatial patterns of variability are not simply related to a passive ocean response to heating and cooling but involve changes in its 3-dimensional circulation. Uncertainties in mean sea level estimates remain large given the possibility of systematic errors in all datasets, including the atmospheric surface fluxes. Various ways of improving model formulation and implementation of data constraints relevant for determining global mean quantities are examined.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. Links between Sea Level in the northern Adriatic sea and large scale patterns

    NASA Astrophysics Data System (ADS)

    Scarascia, L.; Lionello, P.

    2012-04-01

    The study analyzes the link between Northern Adriatic sea level (SL) and three variables: sea level pressure over European and North-Atlantic area (SLP), Mediterranean sea surface temperature (SST) and Mediterranean sea surface salinity (SSS). Sea level data are provided by monthly values recorded at 7 tide gauges stations distributed along the north-Italian and Croatian coasts (available at the PSMSL Permanent Service of Mean Sea Level). SLP data are provided by the EMULATE data set. Mediterranean SST and SSS data are extracted from the MEDATLAS/2002 database. The study shows that annual sea level variations at Northern Adriatic stations are very coherent so that the northern Adriatic sea level can be reconstructed since 1905 on the basis of only two stations: Venice and Trieste, whose data cover almost the entire 20th century (whereas Croatian data cover only the second half of the century). The inverse barometric, thermosteric and halosteric effects provide the physical basis for a local relation of SL with SLP, SST, SSS implying, if other effects are absent, a sea level increase for increasing temperature and decreasing atmospheric pressure and salinity. However, the statistical model used to quantify the link between SL and these three forcings shows that they have produced no important trend and they cannot explain the observed trend of Northern Adriatic Sea level during the second half of the 20th century. The observed trend can therefore be interpreted as the superposition of land movement and a remote cause. Using SLP, SST and SSS from climate model simulations, no trend is obtained during the 20th century, as well. The same model simulations, considering their continuations for the 21st century show that local effects (mainly warming of water masses) are likely to produce an increase of about 10cm (with a large uncertainty) at the end of the century. The global signal and the regional land movements have to be added to this result to obtain the actual

  17. 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

  18. Sea-Level Rise Impacts on Hudson River Marshes

    NASA Astrophysics Data System (ADS)

    Hooks, A.; Nitsche, F. O.

    2015-12-01

    The response of tidal marshes to increasing sea-level rise is uncertain. Tidal marshes can adapt to rising sea levels through vertical accretion and inland migration. Yet tidal marshes are vulnerable to submergence if the rate of sea-level rise exceeds the rate of accretion and if inland migration is limited by natural features or development. We studied how Piermont and Iona Island Marsh, two tidal marshes on the Hudson River, New York, would be affected by sea-level rise of 0.5m, 1m, and 1.5m by 2100. This study was based on the 2011-2012 Coastal New York LiDAR survey. Using GIS we mapped sea-level rise projections accounting for accretion rates and calculated the submerged area of the marsh. Based on the Hudson River National Estuarine Research Reserve Vegetation 2005 dataset, we studied how elevation zones based on vegetation distributions would change. To evaluate the potential for inland migration, we assessed land cover around each marsh using the National Land Cover Database 2011 Land Cover dataset and examined the slope beyond the marsh boundaries. With an accretion rate of 0.29cm/year and 0.5m of sea-level rise by 2100, Piermont Marsh would be mostly unchanged. With 1.5m of sea-level rise, 86% of Piermont Marsh would be flooded. For Iona Island Marsh with an accretion rate of 0.78cm/year, sea-level rise of 0.5m by 2100 would result in a 4% expansion while 1.5m sea-level rise would cause inundation of 17% of the marsh. The results indicate that Piermont and Iona Island Marsh may be able to survive rates of sea-level rise such as 0.5m by 2100 through vertical accretion. At rates of sea-level rise like 1.5m by 2100, vertical accretion cannot match sea-level rise, submerging parts of the marshes. High elevations and steep slopes limit Piermont and Iona Island Marsh's ability to migrate inland. Understanding the impacts of sea-level rise on Piermont and Iona Island Marsh allows for long-term planning and could motivate marsh conservation programs.

  19. 50 CFR 648.143 - Black sea bass Accountability Measures.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false Black sea bass Accountability Measures... Management Measures for the Black Sea Bass Fishery § 648.143 Black sea bass Accountability Measures. (a..., from a subsequent single fishing year recreational sector ACT. (c) Non-landing accountability...

  20. 50 CFR 648.143 - Black sea bass Accountability Measures.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Black sea bass Accountability Measures... Management Measures for the Black Sea Bass Fishery § 648.143 Black sea bass Accountability Measures. (a..., from a subsequent single fishing year recreational sector ACT. (c) Non-landing accountability...

  1. 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

  2. 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

  3. 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.

  4. Assessing impacts of sea level rise on river salinity in the Gorai river network, Bangladesh

    NASA Astrophysics Data System (ADS)

    Bhuiyan, Md. Jabed Abdul Naser; Dutta, Dushmanta

    2012-01-01

    Coastal zones are particularly vulnerable to climate change effects. Over the last century, sea level rose on average by 10-12 cm per decade and did so at much higher rates in some coastal areas due to land subsidence. The 4th IPCC report highlights the increased vulnerability of the coastal zones around the world due to sea level rises in 21st Century. Key concerns due to sea level rise include flooding and salinisation and its implications for water resources. Rising sea level increases the salinity of both surface water and ground water through salt water intrusion. It is important to determine the impacts of sea level rise on salinity to devise suitable adaptation and mitigation measures and reduce impacts of salinity intrusion in coastal cities. The paper presents the outcomes of a study conducted in the coastal area of Gorai river network in the South West region of Bangladesh for developing a comprehensive understanding of the possible effects of sea level rise with the aid of a hydrodynamic model. A newly developed salinity flux model has been integrated with an existing hydrodynamic model in order to simulate flood and salinity in the complex waterways in the coastal zone of Gorai river basin. The integrated model has been calibrated and validated by numerous comparisons with measurements (tide, salinity). The model has been applied for future scenarios with sea level rise and the results obtained indicate the risk and changes in salinity. Due to sea level rise, the salinity has increased in the river and salinity intrusion length has also increased. Sea level rise of 59 cm produced a change of 0.9 ppt at a distance of 80 km upstream of river mouth, corresponding to a climatic effect of 1.5 ppt per meter sea level rise.

  5. 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

  6. Sea level change: lessons from the geologic record

    USGS Publications Warehouse

    ,

    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.

  7. Determination and characterization of 20th century global sea level rise

    NASA Astrophysics Data System (ADS)

    Kuo, Chung-Yen

    In this study, we provide a determination of the 20th Century (1900--2002) global sea level rise, the associated error budgets, and the quantifications of the various geophysical sources of the observed sea level rise, using data and geophysical models. We analyzed significant geographical variations of the global sea level including those caused by the steric component (heat and salinity) in the ocean, and the self-gravitational signal as a result of ice sheets melting, including the effects of glacial isostatic adjustment (GIA) since the Pleistocene. In particular, relative sea level data from long-term (longest is 150 year records) and over 600 tide gauge sites globally from PSMSL and other sources, and geocentric sea level data from multiple satellite altimetry (1985--2005) have been used to determine and characterize 20th century global sea level rise. Altimeter and selected tide gauge sea level data have been used for the 20th century sea level determination, accounting for relative biases between the altimeters, effects of sea level corresponding to oceanic thermal expansion, vertical motions affecting tide gauge measurements, self gravitations, and barotropic ocean response. This study is also characterized by the roles of the polar ocean in the global sea level study and addressing the question whether there is a detectable sea level rise acceleration during the last decade. Vertical motions have been estimated by combining geocentric sea level measurements from satellite altimetry (TOPEX/POSEIDON) and long-term relative (crust-fixed) sea level records from global tide gauges using the Gauss-Markov (GM) model with stochastic constraints. The study provided a demonstration of improved vertical motion solutions in semi-enclosed seas and lakes, including Fennoscandia and the Great Lakes region, showing excellent agreement with independent GPS observed radial velocities, or with predictions from GIA models. In general, the estimated uncertainty of the observed

  8. Modelling the variations and extremes of the sea level on the Finnish coast in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Kämäräinen, Matti; Kahma, Kimmo K.; Jokinen, Olli; Johansson, Milla M.; Särkkä, Jani

    2014-05-01

    A computationally highly effective model was developed to study the variations and extremes of the sea level in the Baltic Sea. The sea level model consists of two main components: 1) The spatial variability as well as the predominantly short-term variability was modelled by a simple barotropic dynamic model (Hansen), which was implemented by modelling the Baltic Sea as an enclosed basin. 2) The spatially uniform, predominantly long-term variability, was modelled by a water balance model of the Baltic Sea, which is based on the regression coefficients of the cross correlation function of the sea level and the zonal wind near the Danish Straits. Both sea level model components are forced by the air pressure gradient -based geostrophic wind, and component 1) in addition directly by the sea level air pressure distribution. For geostrophic wind calculations the 2-meter temperature field is used in addition, and for the transformation to the surface winds a location-based downscaling is applied. Atmospheric reanalysis ERA-40 (1961-2000) and the sea level observations from the Finnish tide gauge network were used to optimize the model system, both the atmospheric and the sea components. The model performance was then evaluated using independet ERA-Interim data from the years 1979-2013. The best correlation and RMS performance, measured between model results and observed sea levels, were 0.93 and 10 cm respectively. The optimised model setup was then used to study the performance of high resolution regional climate models from the ENSEMBLES project above the open Baltic Sea where almost no meteorological observations exist. The hindcast climate model runs forced by ERA-40 were used to evaluate the ability of the climate models to recreate the past low pressure situations in 1961-2000, and the A1B scenario forced runs were used for climate change studies in 1951-2100. Hindcast results with different climate models varied in the range 0.84-0.89 (correlation) and 13-17 cm

  9. 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.

  10. Steric Sea Level Trends in the Northeast Pacific Ocean: Possible Evidence of Global Sea Level Rise.

    NASA Astrophysics Data System (ADS)

    Thomson, Richard E.; Tabata, Susumu

    1989-06-01

    Thirty-year time series of hydrographic observations from Ocean Station PAPA and Line P' are used to estimate secular trends in monthly mean steric sea level heights relative to depths of 100 and 1000 decibars in the northeast Pacific Ocean. Linear trends at station P' (50°N, 145°W) indicate that steric heights relative to the 1000 db (approx. 1000 m) level are rising at a rate of 1.1 mm yr1, comparable with the Order 1 mm yr1 global trends suggested by analysis of selected long-term coastal tide gauge records. Approximately 67% of the increase in steric levels is due to thermosteric change at depths below 100 m, the smaller 33% contribution from the halosteric component apeasrs to be confined to the upper 100 m. Steric height trends at fine P' locations are also of order 1 mm yr1 but, in contrast to station P' trends, arise mainly through the halosteric component.Confidence levels for the linear trends an calculated in two ways. (i) using the Student-t test assuming that cub monthly observation is a statistically independent sample; and (ii) using the Student-t test in conjunction with the effective number of degrees of freedom derived from integral time scales. For station P', trends based on (i) are reliable to the 99% confidence level while for line P' only stations on the eastern portion of the fine have significant trends relative to the 1000 db level. Confidence levels obtained from (i) fail to take into consideration the long-term fluctuations in steric level records. To obtain more reliable estimates of the confidence intervals, we use integral time scales to determine the effective number of degrees of freedom for each monthly time series. Subsequent recalculation of trend-line confidence intervals indicates that the total steric height trends at Station P' remain significant at the 90% confidence level. The halosteric trend relative to 100 db is significant at 90% while the thermosteric trend relative to 1000 db is marginally significant at 70 to 80

  11. 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.

  12. Integrating space geodesy and coastal sea level observations

    NASA Astrophysics Data System (ADS)

    Löfgren, J. S.; Haas, R.; Larson, K.; Scherneck, H.-G.

    2012-04-01

    The goal of the Global Geodetic Observing System (GGOS) is to monitor the Earth system, in particular with observations of the three fundamental geodetic observables: the Earth's shape, the Earth's gravity field and the Earth's rotational motion. A central part of GGOS is the network of globally distributed fundamental geodetic stations that allow the combination and integration of the different space geodetic techniques. One of these stations is the Onsala Space Observatory (OSO), on the west coast of Sweden, which operates equipment for geodetic Very Long Baseline Interferometry, Global Navigation Satellite System (GNSS), and superconducting gravimetry measurements, and additionally water vapour radiometers. The newest addition to the OSO fundamental geodetic station is a GNSS-based tide gauge (GNSS-TG). This installation integrates space geodesy with remote sensing of the local sea level. The GNSS-TG uses both direct GNSS-signals and GNSS-signals that are reflected off the sea surface. This is done using a zenith-looking Right Hand Circular Polarized (RHCP) and a nadir-looking Left Hand Circular Polarized (LHCP) antenna, respectively. Each of the two antennas is connected to a standard geodetic-type GNSS-receiver. The analysis of the data received with the RHCP-antenna allows one to determine land motion, while the analysis of the data received with the LHCP-antenna allows one to determine the sea surface height. Analysing both data sets together results in local sea level that is automatically corrected for land motion, meaning that the GNSS-TG can provide reliable sea-level estimates even in tectonically active regions. Previous results from the GNSS-TG, using carrier phase data, show a Root-Mean-Square (RMS) agreement of less than 5.9 cm with stilling well gauges located 18 km and 33 km away from OSO (Löfgren et al., 2011). This is lower than the RMS agreement between the two stilling well gauges (6.1 cm). Furthermore, significant ocean tidal signals have

  13. The rising tide: Global warming and world sea levels

    SciTech Connect

    Edgerton, L.T.

    1991-01-01

    The author presents a broad-based and well-written approach to the impacts of sea level rise. Besides chapters on global warming, sources of sea level variability and the future, the effects on coastal nations, the book contains an important action-oriented discussion of proposed legislation and guidelines for planning and management aimed at reducing loss and damage produced by sea-level rise. The list of acknowledgements includes all the leading practitioners in the field. The references and information are current; reports and information from 1989 and 1990 meetings are included.

  14. 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.

  15. Sea-level variability over five glacial cycles.

    PubMed

    Grant, K M; Rohling, E J; Ramsey, C Bronk; Cheng, H; Edwards, R L; Florindo, F; Heslop, D; Marra, F; Roberts, A P; Tamisiea, M E; Williams, F

    2014-09-25

    Research on global ice-volume changes during Pleistocene glacial cycles is hindered by a lack of detailed sea-level records for time intervals older than the last interglacial. Here we present the first robustly dated, continuous and highly resolved records of Red Sea sea level and rates of sea-level change over the last 500,000 years, based on tight synchronization to an Asian monsoon record. We observe maximum 'natural' (pre-anthropogenic forcing) sea-level rise rates below 2 m per century following periods with up to twice present-day ice volumes, and substantially higher rise rates for greater ice volumes. We also find that maximum sea-level rise rates were attained within 2 kyr of the onset of deglaciations, for 85% of such events. Finally, multivariate regressions of orbital parameters, sea-level and monsoon records suggest that major meltwater pulses account for millennial-scale variability and insolation-lagged responses in Asian monsoon records.

  16. Sea-level variability over five glacial cycles.

    PubMed

    Grant, K M; Rohling, E J; Ramsey, C Bronk; Cheng, H; Edwards, R L; Florindo, F; Heslop, D; Marra, F; Roberts, A P; Tamisiea, M E; Williams, F

    2014-01-01

    Research on global ice-volume changes during Pleistocene glacial cycles is hindered by a lack of detailed sea-level records for time intervals older than the last interglacial. Here we present the first robustly dated, continuous and highly resolved records of Red Sea sea level and rates of sea-level change over the last 500,000 years, based on tight synchronization to an Asian monsoon record. We observe maximum 'natural' (pre-anthropogenic forcing) sea-level rise rates below 2 m per century following periods with up to twice present-day ice volumes, and substantially higher rise rates for greater ice volumes. We also find that maximum sea-level rise rates were attained within 2 kyr of the onset of deglaciations, for 85% of such events. Finally, multivariate regressions of orbital parameters, sea-level and monsoon records suggest that major meltwater pulses account for millennial-scale variability and insolation-lagged responses in Asian monsoon records. PMID:25254503

  17. Sea water intrusion by sea-level rise: scenarios for the 21st century.

    PubMed

    Loáiciga, Hugo A; Pingel, Thomas J; Garcia, Elizabeth S

    2012-01-01

    This study presents a method to assess the contributions of 21st-century sea-level rise and groundwater extraction to sea water intrusion in coastal aquifers. Sea water intrusion is represented by the landward advance of the 10,000 mg/L iso-salinity line, a concentration of dissolved salts that renders groundwater unsuitable for human use. A mathematical formulation of the resolution of sea water intrusion among its causes was quantified via numerical simulation under scenarios of change in groundwater extraction and sea-level rise in the 21st century. The developed method is illustrated with simulations of sea water intrusion in the Seaside Area sub-basin near the City of Monterey, California (USA), where predictions of mean sea-level rise through the early 21st century range from 0.10 to 0.90 m due to increasing global mean surface temperature. The modeling simulation was carried out with a state-of-the-art numerical model that accounts for the effects of salinity on groundwater density and can approximate hydrostratigraphic geometry closely. Simulations of sea water intrusion corresponding to various combinations of groundwater extraction and sea-level rise established that groundwater extraction is the predominant driver of sea water intrusion in the study aquifer. The method presented in this work is applicable to coastal aquifers under a variety of other scenarios of change not considered in this work. For example, one could resolve what changes in groundwater extraction and/or sea level would cause specified levels of groundwater salinization at strategic locations and times.

  18. Sea level trends in the Southern Ocean over the last century from historical data

    NASA Astrophysics Data System (ADS)

    Testut, Laurent; Martin-Miguez, Belén.; Watson, Christopher; Wöppelmann, Guy; Coleman, Richard; Creach, Ronan; Brolsma, Henk; Handsworth, Roger; Pouvreau, Nicolas; Legrésy, Benoit

    2010-05-01

    It is well known that the spatial distribution of sea level measurements throughout the Southern Ocean is sparse and mostly consists of datasets with short records. The PSMSL (Permanent Service for Mean Sea Level) has only a few sea level time series below 45° South and most of them are shorter than twenty years. The lack of observations constrains the ability to determine or reconstruct global estimates of mean sea level change over the past century. For this reason, any available historical information becomes invaluable for deriving long-term estimates of sea level change in this part of the world. The aim of this presentation is to describe the way we have recovered and analysed the available historic sea level observations made in few sites of the Southern Ocean and to propose new reliable long term sea level trend estimates in this region. The first site is Saint-Paul, a small island of the Southern Indian Ocean where historical measurements were done in 1874 and connected to the permanent GLOSS tide gauge. The two other historical observations were recorded by the Australasian Antarctic Expedition lead by Sir Douglas Mawson in 1912 at Maquarie Island and Cap Denison (Antarctica). The last site concerned by this presentation is the Dumont d'Urville (Antarctica) where historical information from the beginning of the 1950's were found and analysed.

  19. Observing Sea Level Change and its Causes with Satellite Remote Sensing

    NASA Astrophysics Data System (ADS)

    Boening, Carmen; Fu, Lee-Lueng; Landerer, Felix; Willis, Josh

    2016-07-01

    Sea level rise as a response to a changing climate is an imminent threat for coastal communities in the near future. Coastal zone management relies on most accurate predictions of sea level change over the coming decades for planning potential mitigation efforts. Hence, it is of high importance to accurately measure changes and understand physical processes behind them in great detail on a variety of time scales. Satellite observations of sea level height from altimetry have provided an unprecedented understanding of global changes and regional patterns for over two decades. With more and more missions providing now also observations of causes such as water mass changes due to ice melt and land hydrology as well as the ocean heat and salinity budget and local and regional wind patterns, we can now get a comprehensive understanding of the physical processes causing the short to long term changes in sea level. Here, we present an overview of sea level observations in combination with a suite of measurements looking at sea level contributions to provide insight into current and future challenges to understand the sea level budget and its impact on the accuracy of future projections.

  20. 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.

  1. 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

  2. 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

  3. Regional patterns of sea level change in the German North Sea in a worldwide context

    NASA Astrophysics Data System (ADS)

    Wahl, Thomas; Frank, Torsten; Jensen, Jürgen

    2010-05-01

    Sea Level Rise (SLR) is one of the major consequences we are facing in times of a warming climate and it is obvious that a higher sea level influences the heights of occurring storm surges and thus results in a higher risk of inundation for the affected coastal areas. Therefore, regional and global sea level rise are subjects to many recent scientific publications. In contrast, the mean sea level (MSL) and its variability over the last centuries in the German North Sea area have not been analysed in detail up to now. A methodology to analyse observed sea level rise (SLR) in the German Bight, the shallow south-eastern part of the North Sea, is presented. The contribution focuses on the description of the methods used to generate and analyse high quality mean sea level (MSL) time series. Parametric fitting approaches as well as non-parametric data adaptive filters, such as Singular System Analysis (SSA) are applied. For padding non-stationary sea level time series, an advanced approach named Monte-Carlo autoregressive padding (MCAP) is introduced. This approach allows the specification of uncertainties of the behaviour of smoothed time series near the boundaries. The results for the North Sea point to a weak negative acceleration of SLR since 1844 with a strong positive acceleration at the end of the 19th century, to a period of almost no SLR around the 1970s with subsequent positive acceleration and to high recent rates. The comparison between the German North Sea and a global sea level reconstruction clearly reveals the existence of different patterns of SLR. A stronger SLR in the German North Sea area is detected for a period covering some decades starting at the end of the 19th century and for another period covering the last ten to fifteen years. These findings and the indications for the natural variability of this complex system and further research topics will be discussed. This is a German Coastal Engineering Research Council (KFKI) project, funded by the

  4. 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

  5. 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...

  6. 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...

  7. 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...

  8. 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...

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

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 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. Eemian sea-level highstand in the eastern Baltic Sea linked to long-duration White Sea connection

    NASA Astrophysics Data System (ADS)

    Miettinen, Arto; Head, Martin J.; Knudsen, Karen Luise

    2014-02-01

    Revised diatom and new dinoflagellate cyst and benthic foraminiferal data from the eastern Baltic Sea have refined our understanding of Eemian (Last Interglacial; 131-119.5 ka) sea-level change on the Russian Karelia, a former seaway linking the Baltic to the White Sea. Results from Peski, eastern Baltic show the initiation of marine conditions just before 131 ka in the latest Saalian, after the opening of a connection to the North Sea. Following the onset of the Eemian marine highstand and the opening of the White Sea connection at around 130.25 ka, near-fully marine conditions persisted in the eastern Baltic area for ca 6 kyr, until ca 124 ka. For most of the Eemian, a strong thermal stratification in the eastern Baltic resulted from an Arctic and possible North Atlantic water component from the White Sea merging with warmer waters from the North Sea. From ca 124 ka, decreasing salinity indicates the end of the marine highstand and a simultaneous closure of the Baltic Sea-White Sea connection, i.e. a duration of ca 6 kyr for this seaway. The main influence of White Sea inflow appears to be restricted to the eastern Baltic area, although a large submerged area in the Russian Karelia associated with temperate Atlantic waters could have assisted in creating a more oceanic climate for Central Europe.

  11. 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.

  12. The importance of sea-level research (Plinius Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Horton, Benjamin

    2016-04-01

    200 million people worldwide live in coastal regions less than 5 meters above sea level. By the end of the 21st century, this figure is estimated to increase to 500 million. These low-lying coastal regions are vulnerable to changes in sea level brought about by climate change, storms or earthquakes. But the historic and instrumental record is too short to fully understand the climate relationships and capture the occurrence of the rare, but most destructive events. The coastal sedimentary record provides a long-term and robust paleo perspective on the rates, magnitudes and spatial variability of sea-level rise and the frequency (recurrence interval) and magnitude of destructive events. Reconstructions of paleo sea level are important for identifying the meltwater contributions, constraining parameters in Earth-Ice models, and estimating past and present rates of spatially variable sea-level change associated glacial isostatic adjustment, sediment compaction and tidal range variability. Sea-level reconstructions capture multiple phases of climate and sea-level behavior for model calibration and provide a pre-anthropogenic background against which to compare recent trends. Pre-historic earthquakes (Mw>8.0) are often associated with abrupt and cyclical patterns of vertical land-motion that are manifest in coastal sedimentary archives as abrupt changes in relative sea level. Geologic evidence of paleoearthquakes elucidates characteristic and repeated pattern of land-level movements associated with the earthquake-deformation cycle. Tsunamis and storms leave behind anomalous and characteristic sediment that is incorporated into the coastal sedimentary record often as evidence of a high-energy event affecting a low-energy, depositional environment. Records of tsunamis developed from the sedimentary deposits they leave behind improve understanding of tsunami processes and frequency by expanding the age range of events available for study. Reconstructions of paleo storms

  13. 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

  14. 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

  15. 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.

  16. [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.

  17. 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.

  18. A global reanalysis of storm surges and extreme sea levels.

    PubMed

    Muis, Sanne; Verlaan, Martin; Winsemius, Hessel C; Aerts, Jeroen C J H; Ward, Philip J

    2016-06-27

    Extreme sea levels, caused by storm surges and high tides, can have devastating societal impacts. To effectively protect our coasts, global information on coastal flooding is needed. Here we present the first global reanalysis of storm surges and extreme sea levels (GTSR data set) based on hydrodynamic modelling. GTSR covers the entire world's coastline and consists of time series of tides and surges, and estimates of extreme sea levels. Validation shows that there is good agreement between modelled and observed sea levels, and that the performance of GTSR is similar to that of many regional hydrodynamic models. Due to the limited resolution of the meteorological forcing, extremes are slightly underestimated. This particularly affects tropical cyclones, which requires further research. We foresee applications in assessing flood risk and impacts of climate change. As a first application of GTSR, we estimate that 1.3% of the global population is exposed to a 1 in 100-year flood.

  19. A global reanalysis of storm surges and extreme sea levels

    PubMed Central

    Muis, Sanne; Verlaan, Martin; Winsemius, Hessel C.; Aerts, Jeroen C. J. H.; Ward, Philip J.

    2016-01-01

    Extreme sea levels, caused by storm surges and high tides, can have devastating societal impacts. To effectively protect our coasts, global information on coastal flooding is needed. Here we present the first global reanalysis of storm surges and extreme sea levels (GTSR data set) based on hydrodynamic modelling. GTSR covers the entire world's coastline and consists of time series of tides and surges, and estimates of extreme sea levels. Validation shows that there is good agreement between modelled and observed sea levels, and that the performance of GTSR is similar to that of many regional hydrodynamic models. Due to the limited resolution of the meteorological forcing, extremes are slightly underestimated. This particularly affects tropical cyclones, which requires further research. We foresee applications in assessing flood risk and impacts of climate change. As a first application of GTSR, we estimate that 1.3% of the global population is exposed to a 1 in 100-year flood. PMID:27346549

  20. Twenty-two Years of Sea Level Rise

    NASA Video Gallery

    This visualization shows total sea level change between the beginning of 1993 and the end of 2014, based on data collected from the TOPEX/Poisedon, Jason-1, and Jason-2 satellites. Blue regions are...

  1. A global reanalysis of storm surges and extreme sea levels

    NASA Astrophysics Data System (ADS)

    Muis, Sanne; Verlaan, Martin; Winsemius, Hessel C.; Aerts, Jeroen C. J. H.; Ward, Philip J.

    2016-06-01

    Extreme sea levels, caused by storm surges and high tides, can have devastating societal impacts. To effectively protect our coasts, global information on coastal flooding is needed. Here we present the first global reanalysis of storm surges and extreme sea levels (GTSR data set) based on hydrodynamic modelling. GTSR covers the entire world's coastline and consists of time series of tides and surges, and estimates of extreme sea levels. Validation shows that there is good agreement between modelled and observed sea levels, and that the performance of GTSR is similar to that of many regional hydrodynamic models. Due to the limited resolution of the meteorological forcing, extremes are slightly underestimated. This particularly affects tropical cyclones, which requires further research. We foresee applications in assessing flood risk and impacts of climate change. As a first application of GTSR, we estimate that 1.3% of the global population is exposed to a 1 in 100-year flood.

  2. Does Sea Level Change When a Floating Iceberg Melts?

    NASA Astrophysics Data System (ADS)

    Lan, Boon Leong

    2010-05-01

    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 answer2-4 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 conventional answer is due to the wrong assumption that water from a melted iceberg has the same density as seawater. An iceberg is freshwater ice.5 The sea level rise is essentially due to the difference in the density of seawater (1024 kg/m3) and freshwater (1000 kg/m3). A simple experiment, suitable as an introductory laboratory exercise, that validates the predicted sea level rise is presented at the end of the paper.

  3. A global reanalysis of storm surges and extreme sea levels.

    PubMed

    Muis, Sanne; Verlaan, Martin; Winsemius, Hessel C; Aerts, Jeroen C J H; Ward, Philip J

    2016-01-01

    Extreme sea levels, caused by storm surges and high tides, can have devastating societal impacts. To effectively protect our coasts, global information on coastal flooding is needed. Here we present the first global reanalysis of storm surges and extreme sea levels (GTSR data set) based on hydrodynamic modelling. GTSR covers the entire world's coastline and consists of time series of tides and surges, and estimates of extreme sea levels. Validation shows that there is good agreement between modelled and observed sea levels, and that the performance of GTSR is similar to that of many regional hydrodynamic models. Due to the limited resolution of the meteorological forcing, extremes are slightly underestimated. This particularly affects tropical cyclones, which requires further research. We foresee applications in assessing flood risk and impacts of climate change. As a first application of GTSR, we estimate that 1.3% of the global population is exposed to a 1 in 100-year flood. PMID:27346549

  4. 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

  5. Contribution of Iceland's Ice Caps to Sea Level Change

    NASA Astrophysics Data System (ADS)

    Bjornsson, H.; Gudmundsson, S.; Pálsson, F.; Magnusson, E.; Sigurdsson, O.; Johannesson, T.; Thorsteinsson, T.; Berthier, E.

    2011-12-01

    We report on the volume change of Icelandic ice caps during several time intervals from the 1980s until present. Changes in ice volume have been monitored by both annual mass balance measurements on the glaciers and by comparison of multi-temporal digital surface elevation models derived from various satellite and airborne remote observations. The glaciers' mass budgets have declined significantly, from being close to zero in the 1980s and early 1990s, to becoming on average negative by -0.7 to -1.8 m w.e. per year since the mid 1990s. This reduction in mass balance is related to rapid climate warming in Iceland, approx. 1.5 °C since the early 1980s. High mass balance sensitivities of -1 to -2 m w. e. per °C are identified. The current contribution of Icelandic ice caps to sea level change is estimated to be ~0.03 mm SLE per year. Icelandic ice caps contain in total approx. 3,600 cubic km of ice, which if melted would raise sea level by approx. 1 cm.

  6. SEA-LEVEL RISE. Sea-level rise due to polar ice-sheet mass loss during past warm periods.

    PubMed

    Dutton, A; Carlson, A E; Long, A J; Milne, G A; Clark, P U; DeConto, R; Horton, B P; Rahmstorf, S; Raymo, M E

    2015-07-10

    Interdisciplinary studies of geologic archives have ushered in a new era of deciphering magnitudes, rates, and sources of sea-level rise from polar ice-sheet loss during past warm periods. Accounting for glacial isostatic processes helps to reconcile spatial variability in peak sea level during marine isotope stages 5e and 11, when the global mean reached 6 to 9 meters and 6 to 13 meters higher than present, respectively. Dynamic topography introduces large uncertainties on longer time scales, precluding robust sea-level estimates for intervals such as the Pliocene. Present climate is warming to a level associated with significant polar ice-sheet loss in the past. Here, we outline advances and challenges involved in constraining ice-sheet sensitivity to climate change with use of paleo-sea level records. PMID:26160951

  7. SEA-LEVEL RISE. Sea-level rise due to polar ice-sheet mass loss during past warm periods.

    PubMed

    Dutton, A; Carlson, A E; Long, A J; Milne, G A; Clark, P U; DeConto, R; Horton, B P; Rahmstorf, S; Raymo, M E

    2015-07-10

    Interdisciplinary studies of geologic archives have ushered in a new era of deciphering magnitudes, rates, and sources of sea-level rise from polar ice-sheet loss during past warm periods. Accounting for glacial isostatic processes helps to reconcile spatial variability in peak sea level during marine isotope stages 5e and 11, when the global mean reached 6 to 9 meters and 6 to 13 meters higher than present, respectively. Dynamic topography introduces large uncertainties on longer time scales, precluding robust sea-level estimates for intervals such as the Pliocene. Present climate is warming to a level associated with significant polar ice-sheet loss in the past. Here, we outline advances and challenges involved in constraining ice-sheet sensitivity to climate change with use of paleo-sea level records.

  8. 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.

  9. Mean annual variation of sea level in the Pacific Ocean

    SciTech Connect

    Wyrtki, K.; Leslie, W.G.

    1980-08-01

    The mean annual variation of sea level in the Pacific Ocean is documented on the basis of sea level records from 169 stations along the continental margins and on islands. The results are displayed in numerical and graphical form. The data were also subjected to a harmonic analysis to determine the amplitudes and phases of the annual and semi-annual variations. The distribution of the harmonic parameters and of some derived quantities are charted and discussed.

  10. Climate change. How fast are sea levels rising?

    PubMed

    Church, J A

    2001-10-26

    Sea levels are rising as a result of global warming, but assessing the rate of the rise is proving difficult. In his Perspective, Church highlights the report by Cabanes et al., who have reassessed observational data and find that it is closer to model estimates than previously found. However, observational data are still limited and models disagree in their regional projections. With present data and models, regional sea-level changes cannot be predicted with confidence.

  11. Sea-level trends and interannual variability in the Caribbean Sea

    NASA Astrophysics Data System (ADS)

    Torres, R. Ricardo; Tsimplis, Michael N.

    2013-06-01

    Sea-level trends and their forcing have been investigated in the Caribbean Sea using altimetry and tide gauge time series from 19 stations. The basin average sea-level rise is 1.7 ± 1.3 mm yr-1 for the period 1993-2010. Significant spatial variability of the trends is found. The steric variability above 800 m combined with the global isostatic adjustment explains the observed trends for the altimetry period in most of the basin. Wind forcing changes causes the trends in the southern part of the basin, modulating the sea level through changes in the ocean circulation. The longest time series (102 years) of Cristobal shows a trend of 1.9 ± 0.1 mm yr-1 insignificantly different from the global mean sea-level rise for the twentieth century. By contrast Cartagena, a world heritage site, has a large trend (5.3 ± 0.3 mm yr-1) significantly affected by local vertical land movements. Stations dominated by the steric contribution have smaller trends (˜1.3 ± 0.2 mm yr-1). Sea-level trends at tide gauges are not affected by atmospheric pressure changes or by the open ocean steric contribution at most stations. Decadal variability in the sea-level trends can partly be explained by steric and wind variability. The decadal variability in the trends is not spatially coherent. Interannual sea-level variability accounts for one third of the total sea-level variability and can be partly explained by the influence of El Niño-Southern Oscillation at different time and spatial scales. No correlation with the North Atlantic Oscillation is found.

  12. Adrenocortical suppression in highland chick embryos is restored during incubation at sea level.

    PubMed

    Salinas, Carlos E; Villena, Mercedes; Blanco, Carlos E; Giussani, Dino A

    2011-01-01

    By combining the chick embryo model with incubation at high altitude, this study tested the hypothesis that development at high altitude is related to a fetal origin of adrenocortical but not adrenomedullary suppression and that hypoxia is the mechanism underlying the relationship. Fertilized eggs from sea-level or high altitude hens were incubated at sea level or high altitude. Fertilized eggs from sea-level hens were also incubated at altitude with oxygen supplementation. At day 20 of incubation, embryonic blood was taken for measurement of plasma corticotropin, corticosterone, and Po(2). Following biometry, the adrenal glands were collected and frozen for measurement of catecholamine content. Development of chick embryos at high altitude led to pronounced adrenocortical blunting, but an increase in adrenal catecholamine content. These effects were similar whether the fertilized eggs were laid by sea-level or high altitude hens. The effects of high altitude on the stress axes were completely prevented by incubation at high altitude with oxygen supplementation. When chick embryos from high altitude hens were incubated at sea level, plasma hormones and adrenal catecholamine content were partially restored toward levels measured in sea-level chick embryos. There was a significant correlation between adrenocortical blunting and elevated adrenal catecholamine content with both asymmetric growth restriction and fetal hypoxia. The data support the hypothesis tested and provide evidence to isolate the direct contribution of developmental hypoxia to alterations in the stress system.

  13. Extreme Sea Levels and Approaches to Adaptation in Germany

    NASA Astrophysics Data System (ADS)

    Weisse, R.; Kappenberg, J.; Sothmann, J.

    2014-12-01

    Germany's coastal areas are exposed to extra-tropical storms and related marine hazards such as wind waves and storm surges. About 50% of the coast is below 5 m NN and considerable parts are protected by an almost continuous dike line. Rising mean and extreme sea levels provide substantial threat. In this presentation we briefly review the present situation. Storm related sea level changes are characterized by pronounced inter-annual and decadal variability but do not show a long-term trend over the last century. Mean sea level has increased over the past about 100-150 years at a rate roughly comparable to global mean sea level rise. As a consequence extreme sea levels have increased in the area as increasing mean sea level shifts the baseline for storm surges and wind waves towards higher values. Different approaches for adaptation are investigated in a number ongoing research projects. Some case studies for potential adaptation and challenges are presented. Examples range from detailed analyses of retreat and accommodation strategies to multi-purpose strategies such as concepts for sustainable development of tidal estuaries.

  14. 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.

  15. Sea level Variability and Juan de Fuca Bathymetry

    NASA Astrophysics Data System (ADS)

    Huybers, P. J.; Boulahanis, B.; Proistosescu, C.; Langmuir, C. H.; Carbotte, S. M.; Katz, R. F.

    2015-12-01

    That deglaciation influences mid-ocean ridge volcanism is well established for Iceland, where depressurization associated with melting a ~2 km ice cap led to order of magnitude increases in volcanism during the last deglaciation. The case was also made that the more subtle ~100 m changes in sea level that accompany glacial cycles have identifiable implications for undersea mid-ocean ridge systems using both models and data from the Australian-Antarctic Ridge (Crowley et al., 2015). Sea level rising at ~1 cm/year during deglaciation leads to an expectation of ~10% decreases in melt production at ridges, given mantle upwelling rates of ˜3 cm/yr at intermediate spreading ridges and mantle density being ~3 times that of seawater. The implications of variations in melt production for bathymetry, however, involve numerous considerations, including whether melt signals are cancelled within the melt column, appreciably alter accretionary or fault processes, and have identifiable surface expressions. Further empirical assessment of bathymetry is thus useful for purposes of confirming patterns and constraining processes. Here we report on spectral analyses of bathymetry recently acquired from the Juan de Fuca ridge between 44°30'N and 45°15'N during the SeaVOICE expedition. Multibeam swath sonar data were acquired with an EM122 sonar insonfiying seafloor to crustal ages of ˜2 ma with 35 m spatial resolution. We examine (1.) the statistical significance of concentrations of bathymetric variability at the 100 ky, 41 ky, and 23 ky periods characteristic of late-Pleistocene sea level variability; (2.) whether sea level responses are primarily at 41 ky periods in crust accreted during the early Pleistocene, when global sea level variations were primarily at this period; and (3.) if sea level responses are superimposed on bathymetry variations or, instead, align with fault features. We also note that Juan de Fuca's proximity to the Cordilleran Ice Sheet implies that regional

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Method for Assessing Impacts of Global Sea Level Rise on Navigation Gate Operations

    NASA Astrophysics Data System (ADS)

    Obrien, P. S.; White, K. D.; Friedman, D.

    2015-12-01

    Coastal navigation infrastructure may be highly vulnerable to changing climate, including increasing sea levels and altered frequency and intensity of coastal storms. Future gate operations impacted by global sea level rise will pose unique challenges, especially for structures 50 years and older. Our approach is to estimate future changes in gate operational frequency based on a bootstrapping method to forecast future water levels. A case study will be presented to determine future changes in frequency of operations over the next 100 years. A statistical model in the R programming language was developed to apply future sea level rise projections using the three sea level rise scenarios prescribed by USACE Engineer Regulation ER 1100-2-8162. Information derived from the case study will help forecast changes in operational costs caused by increased gate operations and inform timing of decisions on adaptation measures.

  1. The effects of aggressive mitigation on steric sea level rise and sea ice changes

    NASA Astrophysics Data System (ADS)

    Körper, J.; Höschel, I.; Lowe, J. A.; Hewitt, C. D.; Salas y Melia, D.; Roeckner, E.; Huebener, H.; Royer, J.-F.; Dufresne, J.-L.; Pardaens, A.; Giorgetta, M. A.; Sanderson, M. G.; Otterå, O. H.; Tjiputra, J.; Denvil, S.

    2013-02-01

    With an increasing political focus on limiting global warming to less than 2 °C above pre-industrial levels it is vital to understand the consequences of these targets on key parts of the climate system. Here, we focus on changes in sea level and sea ice, comparing twenty-first century projections with increased greenhouse gas concentrations (using the mid-range IPCC A1B emissions scenario) with those under a mitigation scenario with large reductions in emissions (the E1 scenario). At the end of the twenty-first century, the global mean steric sea level rise is reduced by about a third in the mitigation scenario compared with the A1B scenario. Changes in surface air temperature are found to be poorly correlated with steric sea level changes. While the projected decreases in sea ice extent during the first half of the twenty-first century are independent of the season or scenario, especially in the Arctic, the seasonal cycle of sea ice extent is amplified. By the end of the century the Arctic becomes sea ice free in September in the A1B scenario in most models. In the mitigation scenario the ice does not disappear in the majority of models, but is reduced by 42 % of the present September extent. Results for Antarctic sea ice changes reveal large initial biases in the models and a significant correlation between projected changes and the initial extent. This latter result highlights the necessity for further refinements in Antarctic sea ice modelling for more reliable projections of future sea ice.

  2. Ice2sea - the future glacial contribution to sea-level rise

    NASA Astrophysics Data System (ADS)

    Vaughan, D. G.; Ice2sea Consortium

    2009-04-01

    The melting of continental ice (glaciers, ice caps and ice sheets) is a substantial source of current sea-level rise, and one that is accelerating more rapidly than was predicted even a few years ago. Indeed, the most recent report from Intergovernmental Panel on Climate Change highlighted that the uncertainty in projections of future sea-level rise is dominated by uncertainty concerning continental ice, and that understanding of the key processes that will lead to loss of continental ice must be improved before reliable projections of sea-level rise can be produced. Such projections are urgently required for effective sea-defence management and coastal adaptation planning. Ice2sea is a consortium of European institutes and international partners seeking European funding to support an integrated scientific programme to improve understanding concerning the future glacial contribution to sea-level rise. This includes improving understanding of the processes that control, past, current and future sea-level rise, and generation of improved estimates of the contribution of glacial components to sea-level rise over the next 200 years. The programme will include targeted studies of key processes in mountain glacier systems and ice caps (e.g. Svalbard), and in ice sheets in both polar regions (Greenland and Antarctica) to improve understanding of how these systems will respond to future climate change. It will include fieldwork and remote sensing studies, and develop a suite of new, cross-validated glacier and ice-sheet model. Ice2sea will deliver these results in forms accessible to scientists, policy-makers and the general public, which will include clear presentations of the sources of uncertainty. Our aim is both, to provide improved projections of the glacial contribution to sea-level rise, and to leave a legacy of improved tools and techniques that will form the basis of ongoing refinements in sea-level projection. Ice2sea will provide exciting opportunities for many

  3. Sea-level and the `Stage 11 Problem`

    NASA Astrophysics Data System (ADS)

    Bowen, D. Q.

    2003-12-01

    Estimating an approximate relative sea level for oxygen isotope stage 11 may have a critical bearing on a solution to the `stage 11 problem` that identifies the mismatch between low eccentricity forcing and the disproportionate ice volume response - that also includes a relative sea level response. The perennial problem of separating ice volume from temperature effects has hampered attempts to estimate sea level from delta 18O data sets, even for younger odd numbered stages when comparisons with U-series ages on corals are available. Stage 11 sea levels on `stable` and uplifting coasts are recognised from geomorphic features such as terraces and shoreline angles, sediments and corals, and yield a range of estimates from over 20 m to just below present sea level. Given that the 413 ka Milankovitch pacing provides similar orbital configurations for stage 11 and the Holocene some interest attaches to the potential sea-level similarity between them, especially for the future Holocene. Attempts to derive a stage 11 sea level from coasts uplifting at different rates have used `uplift correction graphs` or uplift correction equations, but a major handicap is the dearth of appropriate geochronologic ages both for stage 11 and substage 5e (5.5) - the base line for estimating average uplift rates. Different estimates for the age of stage 11 and 5e (5.5), and the duration of 5e, have yielded a range of estimates. Earlier estimates relied on single locations or regional evidence, but it is probably misleading to rely on these. To combat this several world-wide locations are assembled and, using locality-specific data, provide a mean estimate for the stage 11 sea level of 11 m, plus-minus 10 m. But by applying a set of standardised parameters (including the peak sea level at 402 ka - event 11.3 of the Bassinott time scale) the mean sea level for stage 11 emerges as 2 m plus-minus 7 m. This closes the gap between inferences from delta 18O variability, the latest of which point

  4. The response of tropical Australian estuaries to a sea level rise

    NASA Astrophysics Data System (ADS)

    Wolanski, E.; Chappell, J.

    1996-02-01

    Estuaries in tropical Australia have a low sediment yield (about 5-20 tonnes km -2 yr -1). The estuaries formed when rising post-glacial sea level invaded coastal valleys 7 to 9000 years ago. Geomorphological and stratigraphic data show that mangrove swamps developed on the flooded plains and in some cases their substrate kept pace with the rising sea level. The bulk of the sediment originated from the sea. When sea level stabilised, 6000 years ago, the flood plains prograded seaward. The channels now are generally stable and in some cases are inherited from the progradation phase. The response of these estuaries to a sea level rise may be inferred both from their evolution during post glacial sea level rise and from hydrodynamics-sedimentological models calibrated against measurements of tidal processes. This was undertaken for Coral Creek, the South Alligator River and the Norman River in north Australia. Modelling indicates that a future sea level rise will generate changes in the dynamics and channel dimensions which mimic post glacial changes. In the macrotidal South Alligator the floodplain will revert to mangrove, the mouth region will widen and sediment will move upstream and onto the floodplain. In the mesotidal, diurnal Norman the channel will widen throughout and sediment will be transported seawards. In Coral Creek the mangrove will retreat landwards.

  5. Nonlinear trends and multi-year cycles in regional and global sea level records

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    We analyze the Permanent Service for Mean Sea Level (PSMSL) database of sea level time series using a method based on Monte Carlo Singular Spectrum Analysis (MC-SSA). We remove 2-30 year quasi- periodic oscillations and determine the nonlinear long-term trends for 12 large ocean regions. Our global sea level trend estimate of 2.4 ± 1.0 mm/yr for the period from 1993 to 2000 is comparable with the 2.6 ± 0.7 mm/yr sea level rise calculated from TOPEX/Poseidon altimeter measurements. However, we show that over the last 100 years the rate of 2.5 ± 1.0 mm/yr occurred between 1920 and 1945, is likely to be as large as the 1990s, and resulted in a mean sea level rise of 48 mm. We evaluate errors in sea level using two independent approaches, the robust bi-weight mean and variance, and a novel "virtual station" approach that utilizes geographic locations of stations. Results suggest that a region cannot be adequately represented by a simple mean curve with standard error, assuming all stations are independent, as multi-year cycles within regions are very significant. Additionally, much of the between-region mismatch errors are due to multi-year cycles in the global sea level that limit the ability of simple means to capture sea level accurately. We demonstrate that variability in sea level records over periods 2-30 years has increased during the past 50 years in most ocean basins.

  6. Sea-level-induced seismicity and submarine landslide occurrence

    USGS Publications Warehouse

    Brothers, Daniel S.; Luttrell, Karen M.; Chaytor, Jason D.

    2013-01-01

    The temporal coincidence between rapid late Pleistocene sea-level rise and large-scale slope failures is widely documented. Nevertheless, the physical mechanisms that link these phenomena are poorly understood, particularly along nonglaciated margins. Here we investigate the causal relationships between rapid sea-level rise, flexural stress loading, and increased seismicity rates along passive margins. We find that Coulomb failure stress across fault systems of passive continental margins may have increased more than 1 MPa during rapid late Pleistocene–early Holocene sea-level rise, an amount sufficient to trigger fault reactivation and rupture. These results suggest that sea-level–modulated seismicity may have contributed to a number of poorly understood but widely observed phenomena, including (1) increased frequency of large-scale submarine landslides during rapid, late Pleistocene sea-level rise; (2) emplacement of coarse-grained mass transport deposits on deep-sea fans during the early stages of marine transgression; and (3) the unroofing and release of methane gas sequestered in continental slope sediments.

  7. Nordic Sea Level - Analysis of PSMSL RLR Tide Gauge data

    NASA Astrophysics Data System (ADS)

    Knudsen, Per; Andersen, Ole

    2015-04-01

    Tide gauge data from the Nordic region covering a period of time from 1920 to 2000 are evaluated. 63 stations having RLR data for at least 40 years have been used. Each tide gauge data record was averaged to annual averages after the monthly average seasonal anomalies were removed. Some stations lack data, especially before around 1950. Hence, to compute representative sea level trends for the 1920-2000 period a procedure for filling in estimated sea level values in the voids, is needed. To fill in voids in the tide gauge data records a reconstruction method was applied that utilizes EOF.s in an iterative manner. Subsequently the trends were computed. The estimated trends range from about -8 mm/year to 2 mm/year reflecting both post-glacial uplift and sea level rise. An evaluation of the first EOFs show that the first EOF clearly describes the trends in the time series. EOF #2 and #3 describe differences in the inter-annual sea level variability with-in the Baltic Sea and differences between the Baltic and the North Atlantic / Norwegian seas, respectively.

  8. Global coastal hazards from future sea level rise

    NASA Astrophysics Data System (ADS)

    Gornitz, Vivien

    1991-03-01

    A rise of sea level between 0.3 and 0.9 m by the end of the next century, caused by predicted greenhouse climate warming, would endanger human populations, cities, ports, and wetlands in low-lying coastal areas, through inundation, erosion and salinization. The consequences of a global sea level rise would be spatially non-uniform because of local or regional vertical crustal movements, differential resistance to erosion, varying wave climates, and changeable longshore currents. Although many factors can influence sea level, leading to a noisy record, various studies utilizing tide-gauge data find an average global rate of sea level rise of 1-2 mm/yr, over the last 100 years. This trend is part of a general rise over the last 300 years, since the low point of the Little Ice Age. Sea level rise may accelerate 3-8 times over present rates, within the next century. The permanently inundated coastal zone would extend to a depth equivalent to the vertical rise in sea level. Major river deltas, coastal wetlands and coral islands would be most affected. Episodic flooding by storm waves and surges would penetrate even farther inland. Beach and cliff erosion will be accentuated. Saltwater penetration into coastal aquifers and estuaries could contaminate urban water supplies and affect agricultural production. Research on relative risks and impacts of sea level rise on specific localities is still at an early stage. Development of a global coastal hazards data base, intended to provide an overview of the relative vulnerabilities of the world's coastlines, is described in this paper. To date, information on seven variables, associated with inundation and erosion hazards, has been compiled for the U.S., and parts of Canada and Mexico. A coastal vulnerability index (CVI) has been designed to flag high risk coastal segments. Preliminary results are presented for the eastern United States, as a test case.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Local sea level change and future of Louisiana coast

    SciTech Connect

    Nummedal, D.

    1983-09-01

    The relative elevation of sea and land has been changing through time in response to two fundamentally different groups of factors. Global factors include changes in the volume of the ocean basins owing to tectonic processes and changes in the total amount of ocean water due to glaciation. Local factors include subsidence of continental margins and compaction of recent sediments. Over this century, global sea level (eustatic) appears to have been rising at a rate of 1.2 mm per year. Along the south-central Louisiana coast the land surface appears to be sinking at a rate of about 8 mm per year. Recent global climatic modeling suggests strongly that we are about to enter a period of rapidly accelerating warming due to increased amount of carbon dioxide in the atmosphere. As a consequence, eustatic sea level rise is predicted to accelerate because of both steric expansion of the ocean water and continued melting of polar ice caps. For the next 40 years the eustatic sea level rise may average 10 mm per year. The local relative sea level in coastal Louisiana would therefore rise at about twice its present rate over this time period. The numbers presented above are average value for the Louisiana coastal plain. Local variability in subsidence rate appear to be related to the thickness of Holocene sediments. The highest rates of subsidence are found in the modern Mississippi (birdfoot) delta and in coastal Terrebonne Parish above the late Pleistocene Mississippi trench; in both areas the Holocene section is in excess of 200 m (650 ft) thick. The high rate of local sea level rise along the Louisiana coast makes it imperative that plans for coastal development and protection consider the long-term consequences of sea level change.

  16. 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.

  17. 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

  18. Processes contributing to resilience of coastal wetlands to sea-level rise

    USGS Publications Warehouse

    Stagg, Camille L.; Krauss, Ken W.; Cahoon, Donald R.; Cormier, Nicole; Conner, William H.; Swarzenski, Christopher M.

    2016-01-01

    The objectives of this study were to identify processes that contribute to resilience of coastal wetlands subject to rising sea levels and to determine whether the relative contribution of these processes varies across different wetland community types. We assessed the resilience of wetlands to sea-level rise along a transitional gradient from tidal freshwater forested wetland (TFFW) to marsh by measuring processes controlling wetland elevation. We found that, over 5 years of measurement, TFFWs were resilient, although some marginally, and oligohaline marshes exhibited robust resilience to sea-level rise. We identified fundamental differences in how resilience is maintained across wetland community types, which have important implications for management activities that aim to restore or conserve resilient systems. We showed that the relative importance of surface and subsurface processes in controlling wetland surface elevation change differed between TFFWs and oligohaline marshes. The marshes had significantly higher rates of surface accretion than the TFFWs, and in the marshes, surface accretion was the primary contributor to elevation change. In contrast, elevation change in TFFWs was more heavily influenced by subsurface processes, such as root zone expansion or compaction, which played an important role in determining resilience of TFFWs to rising sea level. When root zone contributions were removed statistically from comparisons between relative sea-level rise and surface elevation change, sites that previously had elevation rate deficits showed a surplus. Therefore, assessments of wetland resilience that do not include subsurface processes will likely misjudge vulnerability to sea-level rise.

  19. 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.

  20. 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

  1. Long-period sea-level variations in the Mediterranean

    NASA Astrophysics Data System (ADS)

    Zerbini, Susanna; Raicich, Fabio; Bruni, Sara; del Conte, Sara; Errico, Maddalena; Prati, Claudio; Santi, Efisio

    2016-04-01

    Since the beginning of its long-lasting lifetime, the Wegener initiative has devoted careful consideration to studying sea-level variations/changes across the Mediterranean Sea. Our study focuses on several long-period sea-level time series (from end of 1800 to 2012) acquired in the Mediterranean by tide gauge stations. In general, the analysis and interpretation of these data sets can provide an important contribution to research on climate change and its impacts. We have analyzed the centennial sea-level time series of six fairly well documented tide gauges. They are: Marseille, in France, Alicante in Spain, Genoa, Trieste, Venice and Marina di Ravenna (formerly Porto Corsini), in Italy. The data of the Italian stations of Marina di Ravenna and Venice clearly indicate that land subsidence is responsible for most of the observed rate of relative sea level rise. It is well known that, in the two areas, subsidence is caused by both natural processes and human activities. For these two stations, using levelling data of benchmarks at, and/or close to, the tide gauges, and for the recent years, also GPS and InSAR height time series, modelling of the long-period non-linear behavior of subsidence was successfully accomplished. After removing the land vertical motions, the estimate of the linear long-period sea-level rise at all six stations yielded remarkably consistent values, between +1,2 and +1,3 mm/yr, with associated errors ranging from ±0,2 to ±0,3 mm/yr (95% confidence interval), which also account for the statistical autocorrelation of the time series. These trends in the Mediterranean area are lower than the global mean rate of 1,7±0,2 mm/yr (1901-2010) presented by the IPCC in its 5th Assessment Report; however, they are in full agreement with a global mean sea-level rise estimate, over the period 1901-1990, recently published by Hay et al. (2015, doi:10.1038/nature14093) and obtained using probabilistic techniques that combine sea-level records with physics

  2. Revisiting Tectonic Corrections Applied to Pleistocene Sea-Level Highstands

    NASA Astrophysics Data System (ADS)

    Creveling, J. R.; Mitrovica, J. X.; Hay, C.; Austermann, J.; Kopp, R. E.

    2015-12-01

    The robustness of stratigraphic- and geomorphic-based inferences of Quaternary peak interglacial sea levels — and equivalent minimum continental ice volumes — depends on the accuracy with which highstand markers can be corrected for vertical tectonic displacement. For sites that preserve a Marine Isotope Stage (MIS) 5e sea-level highstand marker, the customary method for estimating tectonic uplift/subsidence rate computes the difference between the local elevation of the highstand marker and a reference eustatic (i.e., global mean) MIS 5e sea-level height, typically assumed to be +6 m, and then divides this height difference by the age of the highstand marker. This rate is then applied to correct the elevation of other observed sea-level markers at that site for tectonic displacement. Subtracting a reference eustatic value from a local MIS 5e highstand marker elevation introduces two potentially significant errors. First, the commonly adopted peak eustatic MIS 5e sea-level value (i.e., +6 m) is likely too low; recent studies concluded that MIS 5e peak eustatic sea level was ~6-9 m. Second, local peak MIS 5e sea level was not globally uniform, but instead characterized by significant departures from eustasy due to glacial isostatic adjustment (GIA) in response to successive glacial-interglacial cycles and excess polar ice-sheet melt relative to present day. We present numerical models of GIA that incorporate both of these effects in order to quantify the plausible range in error of previous tectonic corrections. We demonstrate that, even far from melting ice sheets, local peak MIS 5e sea level may have departed from eustasy by 2-4 m, or more. Thus, adopting an assumed reference eustatic value to estimate tectonic displacement, rather than a site-specific GIA signal, can introduce significant error in estimates of peak eustatic sea level (and minimum ice volumes) during Quaternary highstands (e.g., MIS 11, MIS 5c and MIS 5a).

  3. Decadal-scale variations of trophic levels at high trophic levels in the Yellow Sea and the Bohai Sea ecosystem

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Tang, Q.; Jin, X.

    2007-09-01

    A total of 2759 stomachs collected from a bottom trawl survey carried out by R/V "Bei Dou" in the Yellow Sea between 32°00 and 36°30N in autumn 2000 and spring 2001 were examined. The trophic levels (TL) of eight dominant fish species were calculated based on stomach contents, and trophic levels of 17 dominant species in the Yellow Sea and the Bohai Sea reported in later 1950s and mid-1980s were estimated so as to be comparable. The results indicated that the mean trophic level at high trophic levels declined from 4.06 in 1959-1960 to 3.41 in 1998-1999, or 0.16-0.19·decade - 1 (mean 0.17·decade - 1 ) in the Bohai Sea, and from 3.61 in 1985-1986 to 3.40 in 2000-2001, or 0.14·decade - 1 in the Yellow Sea; all higher than global trend. The dominant species composition in the Yellow Sea and the Bohai Sea changed, with the percentage of planktivorous species increases and piscivorous or omnivorous species decreases, and this was one of the main reasons for the decline in mean trophic level at high tropic levels. Another main reason was intraspecific changes in TL. Similarly, many factors caused decline of trophic levels in the dominant fish species in the Yellow Sea and the Bohai Sea. Firstly, TL of the same prey got lower, and anchovy ( Engraulis japonicus) as prey was most representative. Secondly, TLs of diet composition getting lower resulted in not only decline of trophic levels but also changed feeding habits of some species, such as spotted velvetfish ( Erisphex pottii) and Trichiurus muticus in the Yellow Sea. Thirdly, species size getting smaller also resulted in not only decline of trophic levels but also changed feeding habits of some species, such as Bambay duck ( Harpodon nehereus) and largehead hairtail ( Trichiurus haumela). Furthermore, fishing pressure and climate change may be interfering to cause fishing down the food web in the China coastal ocean.

  4. Multiple Geodetic Observations for Identifying Glacial Isostatic Adjustment and the Causes of Sea-Level Change

    NASA Astrophysics Data System (ADS)

    Tamisiea, M. E.; Williams, S. D. P.; Hughes, C. W.; Bingley, R.; Blewitt, G.; Hammond, W. C.; Kreemer, C.

    2015-12-01

    Understanding the Earth's and ocean's response to past changes in global ice extent and ocean volume, collectively termed glacial isostatic adjustment (GIA), is necessary for interpreting observations of present-day sea level change. GIA has the largest effect on sea-level observations nearest the locations of the former ice sheets. Under the former loading centers, crustal uplift contributes to a local relative sea-level fall while the collapsing forebulge surrounding these centers accentuates a local sea-level rise. Some of the longest tide gauge records are in these regions. However, GIA also causes global deformation and geoid changes that introduce systematic differences between global averages of tide gauge and altimetry observations. Clearly accounting for the GIA contribution to sea-level change while identifying other present-day contributors is greatly assisted by additional geodetic measurements. Time-variable satellite gravity observations highlight the regional GIA signal, on length scales of hundreds of kilometers, while also locating water mass changes on the continents and the oceans. As the spatial density of GNSS observations has increased, it has become easier to discern the regional characteristics of crustal deformation (e.g. Blewitt et al. abstract in U009). Combined, these two observations allow for greater separation of GIA and water mass changes. More importantly for society, though, the regional crustal estimates could be combined with coastal altimetry products to create regional estimates of relative sea-level change, the observation most relevant for coastal planning. In this presentation we discuss how the various geodetic measurements complement each other and allow us to identify various components of sea level change, including GIA. We illustrate how the weakness of any individual observation component can be overcome by comparison with the other components. A sustained and global geodetic observing system is essential for

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. The sea-level fingerprint of a Snowball Earth deglaciation

    NASA Astrophysics Data System (ADS)

    Creveling, Jessica R.; Mitrovica, Jerry X.

    2014-08-01

    Cap dolostones are thought to represent deposition from seas transgressing over formerly glaciated continental margins during Marinoan Snowball deglaciation. Nevertheless, facies associations within some cap dolostones indicate that an episode of regional regression punctuated these transgressive sequence tracts. To date, inferences of sea-level change during and after the Marinoan Snowball deglaciation have been interpreted using simple, qualitative arguments. In the present study, we explore the full spatio-temporal variability of sea-level change during Snowball deglaciation and its aftermath using a gravitationally self-consistent theory that accounts for the deformational, gravitational and rotational perturbations to sea level on a viscoelastic Earth model. The theory is applied to model Marinoan Snowball deglaciation on a generalized Ediacaran paleogeography with a synthetic continental ice-sheet distribution. We find that sea-level change following a synchronous, rapid (2 kyr) collapse of Snowball ice cover will exhibit significant geographic variability, including site-specific histories that are characterized by syn-deglacial sea-level fall or stillstand. Moreover, some sites that experience syn-deglacial transgression will continue to experience transgression in the post-deglacial phase. Taken together, these results suggest that sea-level change recorded by strata capping Snowball glaciogenic units may reflect a more complicated trajectory than previously thought, including deposition that was not limited to the deglaciation phase. These simulations, as well as others that explore the response to asynchronous melting and deglaciation phases of longer duration, demonstrate that an episode of regional regression interrupting a cap dolostone transgressive sequence tract may reflect one of several processes (or their combination): (1) near field adjustment associated with rapid local melting during an otherwise global hiatus in deglaciation; (2) post

  10. Holocene sea-level changes in the Falkland Islands

    NASA Astrophysics Data System (ADS)

    Newton, Tom; Gehrels, Roland; Daley, Tim; Long, Antony; Bentley, Mike

    2014-05-01

    In many locations in the southern hemisphere, relative sea level (RSL) reached its maximum position during the middle Holocene. This highstand is used by models of glacial isostatic adjustment (GIA) to constrain the melt histories of the large ice sheets, particularly Antarctica. In this paper we present the first Holocene sea-level record from the Falkland Islands (Islas Malvinas), an archipelago located on the Patagonian continental shelf about 500 km east of mainland South America at a latitude of ca. 52 degrees. Unlike coastal locations in southernmost South America, Holocene sea-level data from the Falklands are not influenced by tectonics, local ice loading effects and large tidal ranges such that GIA and ice-ocean mass flux are the dominant drivers of RSL change. Our study site is a salt marsh located in Swan Inlet in East Falkland, around 50 km southwest of Stanley. This is the largest and best developed salt marsh in the Falkland Islands. Cores were collected in 2005 and 2013. Lithostratigraphic analyses were complemented by analyses of foraminifera, testate amoebae and diatoms to infer palaeoenvironments. The bedrock, a Permian black shale, is overlain by grey-brown organic salt-marsh clay, up to 90 cm thick, which, in a landward direction, is replaced by freshwater organic sediments. Overlying these units are medium-coarse sands with occasional pebbles, up to 115 cm thick, containing tidal flat foraminifera. The sandy unit is erosively overlain by a grey-brown organic salt-marsh peat which extends up to the present surface. Further away from the sea this unit is predominantly of freshwater origin. Based on 13 radiocarbon dates we infer that prior to ~9.5 ka sea level was several metres below present. Under rising sea levels a salt marsh developed which was suddenly drowned around 8.4 ka, synchronous with a sea-level jump known from northern hemisphere locations. Following the drowning, RSL rose to its maximum position around 7 ka, less than 0.5 m above

  11. 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)

  12. On the measure of sea ice area from sea ice concentration data sets

    NASA Astrophysics Data System (ADS)

    Boccolari, Mauro; Parmiggiani, Flavio

    2015-10-01

    The measure of sea ice surface variability provides a fundamental information on the climatology of the Arctic region. Sea ice extension is conventionally measured by two parameters, i.e. Sea Ice Extent (SIE) and Sea Ice Area (SIA), both parameters being derived from Sea Ice Concentration (SIC) data sets. In this work a new parameter (CSIA) is introduced, which takes into account only the compact sea-ice, which is defined as the sea-ice having concentration at least equal the 70%. Aim of this study is to compare the performances of the two parameters, SIA and CSIA, in analyzing the trends of three monthly time-series of the whole Arctic region. The SIC data set used in this study was produced by the Institute of Environmental Physics of the University of Bremen and covers the period January 2003 - December 2014, i.e. the period in which the data set is built using the new AMSR passive microwave sensor.

  13. Extreme sea level events in the coastal waters of western Estonia

    NASA Astrophysics Data System (ADS)

    Suursaar, Ülo; Kullas, Tiit; Otsmann, Mikk; Kõuts, Tarmo

    2003-06-01

    Extraordinarily low and high sea level events are analysed on the basis of historical data and their mechanisms of occurrence are studied with the 1 km grid size 2D hydrodynamic model in the two almost tideless semi-enclosed sub-basins of the Baltic Sea, the Gulf of Riga and the Väinameri. The sea level is modelled with realistic meteorological forcing and comparison data from 1999 and 2001. Resonance properties of the sub-basins are studied and their possible role in the formation of extraordinary sea level events is discussed. While the extremely low levels (-1.23 m below the mean sea level) in the Estonian coastal waters do not generally originate locally, the high levels (up to 2.53 m above the mean as measured in the Pärnu Bay) are short-term and local. They occur in combination with several forcing and morphometrical factors and are localised in the shallow and narrow bays exposed to the direction of the strongest possible storm winds, SW and W. Model simulations show that extremely high and low sea levels in some small bays of western Estonia can exceed the corresponding values in the Pärnu Bay.

  14. 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.

  15. Freshening of the South Indian Ocean during the Argo period: observations, causes, and impact on regional sea level change

    NASA Astrophysics Data System (ADS)

    Llovel, William; Lee, Tong

    2015-04-01

    Steric sea level change has been identified as one of the major contributors to the regional sea level changes. This contribution varies in space and time. Temperature (thermosteric) contribution to sea level has been found to be generally more important than salinity (halosteric) effect. Based on temperature and salinity data from Argo floats during 2005-2013 and coincident sea level measurements from satellite altimetry, we found that the central-eastern part of the South Indian Ocean stood out in the entire world ocean as a region that had a more dominant halosteric contribution to sea level change. The conspicuously large halosteric contribution was associated with a freshening in the upper few hundred meters. Neither local atmospheric forcing nor halosteric signal transmitted from the Pacific can explain this freshening. An observed strengthening of the Indonesian throughflow since early 2007 and the enhanced precipitation in the Indonesian Seas inferred from various precipitation estimates compounded by strong tidal mixing are the likely causes of the freshening of the South Indian Ocean. The findings also have implications to the potential influence of regional water cycle and ocean currents in the maritime Continent region to sea level changes in the South Indian Ocean prior to the Argo era and sea level projection in the future in response to climate change. Sustained measurements of sea surface salinity from satellites will significantly enhance our capability to study the impact of regional water cycle in the Maritime Continent region to related changes in the marginal seas and the Indian Ocean.

  16. 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.

  17. 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].

  18. 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].

  19. 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].

  20. 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)

  1. 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.

  2. Coastal Impacts Due to Sea-Level Rise

    NASA Astrophysics Data System (ADS)

    Fitzgerald, Duncan M.; Fenster, Michael S.; Argow, Britt A.; Buynevich, Ilya V.

    2008-05-01

    The Intergovernmental Panel on Climate Change (2007) recently estimated that global sea level will rise from 0.18 to 0.59 m by the end of this century. Rising sea level not only inundates low-lying coastal regions but also contributes to the redistribution of sediment along sandy coasts. Over the long term, sea-level rise (SLR) causes barrier islands to migrate landward while conserving mass through offshore and onshore sediment transport. Under these conditions, coastal systems adjust to SLR dynamically while maintaining a characteristic geometry that is unique to a particular coast. Coastal marshes are susceptible to accelerated SLR because their vertical accretion rates are limited and they may drown. As marshes convert to open water, tidal exchange through inlets increases, which leads to sand sequestration in tidal deltas and erosion of adjacent barrier shorelines.

  3. Quaternary stratigraphy and sea-level history of the U.S. Middle Atlantic Coastal Plain

    NASA Astrophysics Data System (ADS)

    Toscano, Marguerite A.; York, Linda L.

    Middle-Atlantic, inner continental shelf stratigraphic studies document a regional, Late Pleistocene, fossiliferous mud deposit, from northern New Jersey to Cape Lookout, North Carolina. Seismic reconnaissance and detailed stratigraphic analyses reveal the nature of the mud, termed unit Q2, on the Maryland inner continental shelf. Extensive amino acid relative age determinations (from the single genus Mulinia), combined with additional amino acid analyses from onshore deposits having radiometric dates for calibration, indicate an age range for unit Q2 corresponding to Oxygen Isotope Stage 5. Ostracode assemblages delineate four distinct climatic episodes in unit Q2, enabling correlation of the zones in Q2 to the deep sea isotopic record of climatic fluctuations (substages) in Stage 5. Late Stage 5 is represented, on the Maryland shelf, by the 6 meter-thick mud of unit Q2, deposited in an open-shelf environment at slightly depressed sea levels relative to Substage 5e. Late Stage 5 sea levels (including sea-level minima) can be estimated for the mid-Atlantic Coastal Plain by direct measurement of the altitudes of ostracode zone boundaries offshore, and from peak transgressive facies in correlative deposits onshore. Late Stage 5 sea levels determined from the inner shelf and adjacent nearshore facies on the Atlantic coast comprise the most complete sea-level history for Stage 5 yet proposed. Some recent revisions of glacioeustatic sea-level models advocate slightly higher sea levels during late Stage 5 (Substage 5c in particular) than originally estimated from uplifting reef tracts, and support sea levels higher than estimates from deep-sea isotopic records. The sea-level record from the Maryland inner continental shelf confirms these recent estimates in an area of minimal tectonism, and adds sea-level minima estimates for Substages 5d and 5b. Offshore, a more complete record of Stage 5 is preserved than in onshore deposits, which are limited to peak transgressive

  4. Estimations of a global sea level trend: limitations from the structure of the PSMSL global sea level data set

    NASA Astrophysics Data System (ADS)

    Gröger, M.; Plag, H.-P.

    1993-08-01

    Among the possible impacts on environmental conditions of a global warming expected as a consequence of the increasing release of CO 2 and various other greenhouse gases into the atmosphere, a predicted rise in global sea level is considered to be of high importance. Thus, quite a number of recent studies have focused on detecting the "global sea level rise" or even an acceleration of this trend. A brief review of these studies is presented, showing, however, that the results are not conclusive, though most of the studies have been based on a single global data set of coastal tide gauge data provided by the Permanent Service for Mean Sea Level (PSMSL). A detailed discussion of a thoroughly revised subset reveals that the PSMSL data set suffers from three severe limitations: (1) the geographical distribution of reliable tide gauge stations is rather uneven with pronounced concentrations in some areas of the northern hemisphere (Europe, North America, Japan), and much fewer stations on the southern hemisphere where particularly few stations are located in Africa and in Antarctica; (2) the number of stations recording simultaneously at any time is far less than the total number of stations with the maximum within the interval between 1958 and 1988; (3) the number of long records is extremely small and almost all of them originate from a few regions of the northern hemisphere. The sensitivity of the median of the local trends to these temporal and spatial limitations is discussed by restricting the data set in both the spatial and temporal distribution. It is shown that the data base is insufficient for determining an integral value of the global rise in relative sea level. The effect of polar motion on sea level is modelled and it turns out to be locally of the order of 0.5 mm/yr, affecting regional trends to an order of 0.1 mm/yr. Thus, this effect can be neglected on time scale of decades to a hundred years. Though the data set is insufficient for determining an

  5. Evaluating future flooding risks by using a probabilistic approach to include wave height distributions in sea level variations

    NASA Astrophysics Data System (ADS)

    Leijala, Ulpu; Björkqvist, Jan-Victor; Kahma, Kimmo K.; Johansson, Milla M.; Pellikka, Hilkka; Särkkä, Jani

    2016-04-01

    , local land uplift, and changes in the Baltic Sea water balance. Wave statistics in turn are based on individual wave buoy measurements conducted at several sites on the coast off Helsinki during 2012-2014. The method developed in this study is a new tool for evaluating extreme sea level events including the effect of high sea level jointly with high wave height. The method can be applied to any coastal areas where sufficient sea level and wave data are available. The probabilistic approach used here gives a possibility to evaluate the risk levels of different infrastructures on the coast for the present and for the future.

  6. 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.

  7. 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.

  8. 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

  9. Uncertainties in sea level projections on twenty-year timescales

    NASA Astrophysics Data System (ADS)

    Vinogradova, Nadya; Davis, James; Landerer, Felix; Little, Chris

    2016-04-01

    Regional decadal changes in sea level are governed by various processes, including ocean dynamics, gravitational and solid earth responses, mass loss of continental ice, and other local coastal processes. In order to improve predictions and physical attribution in decadal sea level trends, the uncertainties of each processes must be reflected in the sea level calculations. Here we explore uncertainties in predictions of the decadal and bi-decadal changes in regional sea level induced by the changes in ocean dynamics and associated redistribution of heat and freshwater (often referred to as dynamic sea level). Such predictions are typically based on the solutions from coupled atmospheric and oceanic general circulation models, including a suite of climate models participating in phase 5 of the Coupled Model Intercompasion Project (CMIP5). Designed to simulate long-term ocean variability in response to warming climate due to increasing green-house gas concentration ("forced" response), CMIP5 are deficient in simulating variability at shorter time scales. In contrast, global observations of sea level are available during a relatively short time span (e.g., twenty-year altimetry records), and are dominated by an "unforced" variability that occurs freely (internally) within the climate system. This makes it challenging to examine how well observations compare with model simulations. Therefore, here we focus on patterns and spatial characteristics of projected twenty-year trends in dynamic sea level. Based on the ensemble of CMIP5 models, each comprising a 240-year run, we compute an envelope of twenty-year rates, and analyze the spread and spatial relationship among predicted rates. An ensemble root-mean-square average exhibits large-scale spatial patterns, with the largest uncertainties found over mid and high latitudes that could be attributed to the changes in wind patterns and buoyancy forcing. To understand and parameterize spatial characteristics of the

  10. 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.

  11. 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.

  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. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Comparison of TOPEX sea surface heights and tide gauge sea levels

    NASA Technical Reports Server (NTRS)

    Mitchum, Gary T.

    1994-01-01

    TOPEX sea surface height data from the first 300 days of the mission are compared to sea level data from 71 tide gauges. The initial comparison uses sea surface height data processed according to standard procedures as defined in the users handbook. It is found that the median correlations for island and for coastal tide gauges are 0.53 and 0.42, respectively. The analogous root mean square (RMS) differences between the two data sets are 7.9 and 10.4 cm. The comparisons improve significantly when a 60-day harmonic is fit to the differences and removed. This period captures aliased M(sub 2) and S(sub 2) tidal energy that is not removed by the tide model. Making this correction and smoothing the sea surface height data over 25-km along-track segments results in median correlations of 0.58 and 0.46 for the islands and coastal stations, and median RMS differences of 5.8 and 7.7 cm, respectively. Removing once per revolution signals from the sea surface heights results in degraded comparisons with the sea levels. It is also found that a number of stations have poor comparisons due to propagating signals that introduce temporal lags between the altimeter and tide gauge time series. A final comparison is made by eliminating stations where this propagation effect is large, discarding two stations that are suspected to have problems with the sea level data, smoothing over 10-day intervals, and restricting attention to islands gauges. This results in a set of 552 data pairs that have a correlation of 0.66 and a RMS difference of 4.3 cm. The conclusion is that on timescales longer than about 10 days the RMS sea surface height errors are less than or of the order of several centimeters.

  1. Mean and extreme sea level changes in the southwestern Baltic Sea

    NASA Astrophysics Data System (ADS)

    Schmidt, Jessica; Patzke, Justus; Dangendorf, Sönke; Arns, Arne; Jensen, Jürgen; Fröhle, Peter

    2016-04-01

    In this contribution an overview over the BMBF project AMSeL_Ostsee (2015-2018) for the assessment of mean and extreme sea level changes over the past 150 years in the southwestern Baltic Sea is presented. We compile several high resolution tide gauge records provided by the Water and Shipping Administration (WSV) along the German Baltic Sea coastline and merge them in internationally available data bases (UHSLC, PSMSL, and data officially available at national authorities). In addition, we make efforts in digitizing historical records to expand the number of available data sets in this complex and vulnerable coastal region. To separate absolute from relative long-term changes in sea level the vertical land motion (VLM) at specific sites is assessed. Possible sources of VLM are independently assessed by using different state-of-the-art approaches, that is: Glacial Isostatic Adjustment (GIA) modelled by viscoelastic Earth models, GPS derived VLM, and the difference between tide gauge and nearby satellite altimetry. The VLM corrected tide gauge records are further assessed for linear and non-linear trends as well as possible acceleration/deceleration patterns by applying advanced time series models such as Singular System Analysis (SSA) combined with a Monte-Carlo-Autoregressive-Padding approach (Wahl et al., 2010). These trend assessments are applied to mean and extreme sea levels independently to prove whether observed changes in extremes are either due to an underlying trend on mean sea levels or changes in storminess. References: Wahl, T., Jensen, J., Frank, T. (2011): On analysing sea level rise in the German Bight since 1844, NHESS, 10, 171-179.

  2. 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…

  3. 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.

  4. Low-frequency variability in coastal sea level from tide gauges and altimetry

    NASA Astrophysics Data System (ADS)

    Vinogradov, Sergey V.; Ponte, Rui M.

    2011-07-01

    Long sea level observations are fundamental for studies of the low-frequency changes in ocean circulation and climate. Tide gauges provide records several decades long, but their locations are geographically sparse and confined to the coastline. To assess the extent to which tide gauge point measurements represent broader-scale conditions in the adjacent ocean, we compare tide gauge records to altimeter data in their vicinity for the period 1993-2008. The analysis is based on detrended annual mean series and focuses on interannual variability. The best agreement between tide gauge and altimeter series is found for mid-ocean islands in the tropical Pacific and Indian oceans and along the coast of western Australia. Elsewhere, along most continental coasts, root-mean-square differences between the two sea level estimates can be substantial when compared to the observed variability or the expected measurement noise, with the worst correspondence found in western South America, Japan, and eastern Australia. Differences in magnitude as well as poor correlations between the tide gauge and altimeter estimates are involved. Although land motions and measurement errors can be a factor, results point to the presence of considerable short spatial structure in coastal sea level at interannual time scales, which can be related to the low-frequency dynamics of coastally trapped circulations, western boundary currents and associated eddy regimes, or response to river runoff. Knowing whether coastal sea level variability becomes more spatially homogeneous at longer time scales must await longer sea level records.

  5. 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

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

    PubMed Central

    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

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Sea Level Station Metadata for Tsunami Detection, Warning and Research

    NASA Astrophysics Data System (ADS)

    Stroker, K. J.; Marra, J.; Kari, U. S.; Weinstein, S. A.; Kong, L.

    2007-12-01

    The devastating earthquake and tsunami of December 26, 2004 has greatly increased recognition of the need for water level data both from the coasts and the deep-ocean. In 2006, the National Oceanic and Atmospheric Administration (NOAA) completed a Tsunami Data Management Report describing the management of data required to minimize the impact of tsunamis in the United States. One of the major gaps defined in this report is the access to global coastal water level data. NOAA's National Geophysical Data Center (NGDC) and National Climatic Data Center (NCDC) are working cooperatively to bridge this gap. NOAA relies on a network of global data, acquired and processed in real-time to support tsunami detection and warning, as well as high-quality global databases of archived data to support research and advanced scientific modeling. In 2005, parties interested in enhancing the access and use of sea level station data united under the NOAA NCDC's Integrated Data and Environmental Applications (IDEA) Center's Pacific Region Integrated Data Enterprise (PRIDE) program to develop a distributed metadata system describing sea level stations (Kari et. al., 2006; Marra et.al., in press). This effort started with pilot activities in a regional framework and is targeted at tsunami detection and warning systems being developed by various agencies. It includes development of the components of a prototype sea level station metadata web service and accompanying Google Earth-based client application, which use an XML-based schema to expose, at a minimum, information in the NOAA National Weather Service (NWS) Pacific Tsunami Warning Center (PTWC) station database needed to use the PTWC's Tide Tool application. As identified in the Tsunami Data Management Report, the need also exists for long-term retention of the sea level station data. NOAA envisions that the retrospective water level data and metadata will also be available through web services, using an XML-based schema. Five high

  14. 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

  15. 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.

  16. The body weight loss during acute exposure to high-altitude hypoxia in sea level residents.

    PubMed

    Ge, Ri-Li; Wood, Helen; Yang, Hui-Huang; Liu, Yi-Ning; Wang, Xiu-Juan; Babb, Tony

    2010-12-25

    Weight loss is frequently observed after acute exposure to high altitude. However, the magnitude and rate of weight loss during acute exposure to high altitude has not been clarified in a controlled prospective study. The present study was performed to evaluate weight loss at high altitude. A group of 120 male subjects [aged (32±6) years] who worked on the construction of the Golmud-Lhasa Railway at Kunlun Mountain (altitude of 4 678 m) served as volunteer subjects for this study. Eighty-five workers normally resided at sea level (sea level group) and 35 normally resided at an altitude of 2 200 m (moderate altitude group). Body weight, body mass index (BMI), and waist circumference were measured in all subjects after a 7-day stay at Golmud (altitude of 2 800 m, baseline measurements). Measurements were repeated after 33-day working on Kunlun Mountain. In order to examine the daily rate of weight loss at high altitude, body weight was measured in 20 subjects from the sea level group (sea level subset group) each morning before breakfast for 33 d at Kunlun Mountain. According to guidelines established by the Lake Louise acute mountain sickness (AMS) consensus report, each subject completed an AMS self-report questionnaire two days after arriving at Kunlun Mountain. After 33-day stay at an altitude of 4 678 m, the average weight loss for the sea level group was 10.4% (range 6.5% to 29%), while the average for the moderate altitude group was 2.2% (-2% to 9.1%). The degree of weight loss (Δ weight loss) after a 33-day stay at an altitude of 4 678 m was significantly correlated with baseline body weight in the sea level group (r=0.677, P<0.01), while the correlation was absent in the moderate altitude group (r=0.296, P>0.05). In the sea level subset group, a significant weight loss was observed within 20 d, but the weight remained stable thereafter. AMS-score at high altitude was significantly higher in the sea level group (4.69±2.48) than that in the moderate

  17. Revisiting sea level changes in the North Sea during the Anthropocene

    NASA Astrophysics Data System (ADS)

    Jensen, Jürgen; Dangendorf, Sönke; Wahl, Thomas; Niehüser, Sebastian

    2016-04-01

    The North Sea is one of the best instrumented ocean basins in the world. Here we revisit sea level changes in the North Sea region from tide gauges, satellite altimetry, hydrographic profiles and ocean reanalysis data from the beginning of the 19th century to present. This includes an overview of the sea level chapter of the North Sea Climate Change Assessment (NOSCCA) complemented by results from more recent investigations. The estimates of long-term changes from tide gauge records are significantly affected by vertical land motion (VLM), which is related to both the large-scale viscoelastic response of the solid earth to ice melting since the last deglaciation and local effects. Removing VLM (estimated from various data sources such as GPS, tide gauge minus altimetry and GIA) significantly reduces the spatial variability of long-term trends in the basin. VLM corrected tide gauge records suggest a transition from relatively moderate changes in the 19th century towards modern trends of roughly 1.5 mm/yr during the 20th century. Superimposed on the long-term changes there is a considerable inter-annual to multi-decadal variability. On inter-annual timescales this variability mainly reflects the barotropic response of the ocean to atmospheric forcing with the inverted barometer effect dominating along the UK and Norwegian coastlines and wind forcing controlling the southeastern part of the basin. The decadal variability is mostly remotely forced and dynamically linked to the North Atlantic via boundary waves in response to long-shore winds along the continental slope. These findings give valuable information about the required horizontal resolution of ocean models and the necessary boundary conditions and are therefore important for the dynamical downscaling of sea level projections for the North Sea coastlines.

  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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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].

  7. 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.

  8. Plutonium measurements near background levels

    SciTech Connect

    Not Available

    1992-01-01

    The Rocky Flats Plant (RFP) is part of a nationwide nuclear weapons research, development, and production complex administered by the United States Department of Energy (DOE). Low-levels of environmental Plutonium occurs in and about RFP as a result of plant operations. Plutonium is a key element in remediation investigations and surface water discharge limits. Most of the plutonium analyses at RFP measure concentrations at or near background levels. Measurements often show little, if any, plutonium in the media being sampled, except at known contamination sites. Many plutonium results are less than the calculated minimum detectable-level (MDL). (MDL is an a priori estimate of the activity concentration that can be practically achieved under a specified set of typical measurement conditions.) This paper investigates the relationship between plutonium concentrations and the counting uncertainty when measurements are near background, and suggests why the MDL should not be used as a criteria for limiting data. Issues with defining site background and determining attainment of standards are presented.

  9. Plutonium measurements near background levels

    SciTech Connect

    Not Available

    1992-08-01

    The Rocky Flats Plant (RFP) is part of a nationwide nuclear weapons research, development, and production complex administered by the United States Department of Energy (DOE). Low-levels of environmental Plutonium occurs in and about RFP as a result of plant operations. Plutonium is a key element in remediation investigations and surface water discharge limits. Most of the plutonium analyses at RFP measure concentrations at or near background levels. Measurements often show little, if any, plutonium in the media being sampled, except at known contamination sites. Many plutonium results are less than the calculated minimum detectable-level (MDL). (MDL is an a priori estimate of the activity concentration that can be practically achieved under a specified set of typical measurement conditions.) This paper investigates the relationship between plutonium concentrations and the counting uncertainty when measurements are near background, and suggests why the MDL should not be used as a criteria for limiting data. Issues with defining site background and determining attainment of standards are presented.

  10. The Impact of Sea Level Rise on Geodetic Vertical Datum of Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Din, A. H. M.; Abazu, I. C.; Pa'suya, M. F.; Omar, K. M.; Hamid, A. I. A.

    2016-09-01

    Sea level rise is rapidly turning into major issues among our community and all levels of the government are working to develop responses to ensure these matters are given the uttermost attention in all facets of planning. It is more interesting to understand and investigate the present day sea level variation due its potential impact, particularly on our national geodetic vertical datum. To determine present day sea level variation, it is vital to consider both in-situ tide gauge and remote sensing measurements. This study presents an effort to quantify the sea level rise rate and magnitude over Peninsular Malaysia using tide gauge and multi-mission satellite altimeter. The time periods taken for both techniques are 32 years (from 1984 to 2015) for tidal data and 23 years (from 1993 to 2015) for altimetry data. Subsequently, the impact of sea level rise on Peninsular Malaysia Geodetic Vertical Datum (PMGVD) is evaluated in this study. the difference between MSL computed from 10 years (1984 - 1993) and 32 years (1984 - 2015) tidal data at Port Kelang showed that the increment of sea level is about 27mm. The computed magnitude showed an estimate of the long-term effect a change in MSL has on the geodetic vertical datum of Port Kelang tide gauge station. This will help give a new insight on the establishment of national geodetic vertical datum based on mean sea level data. Besides, this information can be used for a wide variety of climatic applications to study environmental issues related to flood and global warming in Malaysia.

  11. Impact of accelerated future global mean sea level rise on hypoxia in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Meier, H. E. M.; Höglund, A.; Eilola, K.; Almroth-Rosell, E.

    2016-08-01

    Expanding hypoxia is today a major threat for many coastal seas around the world and disentangling its drivers is a large challenge for interdisciplinary research. Using a coupled physical-biogeochemical model we estimate the impact of past and accelerated future global mean sea level rise (GSLR) upon water exchange and oxygen conditions in a semi-enclosed, shallow sea. As a study site, the Baltic Sea was chosen that suffers today from eutrophication and from dead bottom zones due to (1) excessive nutrient loads from land, (2) limited water exchange with the world ocean and (3) perhaps other drivers like global warming. We show from model simulations for the period 1850-2008 that the impacts of past GSLR on the marine ecosystem were relatively small. If we assume for the end of the twenty-first century a GSLR of +0.5 m relative to today's mean sea level, the impact on the marine ecosystem may still be small. Such a GSLR corresponds approximately to the projected ensemble-mean value reported by the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. However, we conclude that GSLR should be considered in future high-end projections (>+1 m) for the Baltic Sea and other coastal seas with similar hydrographical conditions as in the Baltic because GSLR may lead to reinforced saltwater inflows causing higher salinity and increased vertical stratification compared to present-day conditions. Contrary to intuition, reinforced ventilation of the deep water does not lead to overall improved oxygen conditions but causes instead expanded dead bottom areas accompanied with increased internal phosphorus loads from the sediments and increased risk for cyanobacteria blooms.

  12. 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

  13. 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.

  14. Cosmic rays with portable Geiger counters: from sea level to airplane cruise altitudes

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

    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 air showers induced by high-energy primary protons in the atmosphere were also carried out, involving undergraduate and graduate teaching levels.

  15. 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.

  16. Sea level rise Contribution from High Mountain Asia by 20150

    NASA Astrophysics Data System (ADS)

    Zhao, Liyun; Moore, John; Ding, Ran

    2015-04-01

    We estimate individual area and volume change by 2050 of all 83,460 glaciers of high mountain Asia (HMA), with a total area of 118,263 km2, delineated in the Randolph Glacier Inventory version 4.0 which separates glacier complexes in its previous version into individual glaciers. We used the 25 km resolution regional climate model RegCM 3.0 temperature and precipitation change projections forced by the IPCC A1B scenario. Glacier simulations were based on a novel surface mass balance-altitude parameterization fitted to observational data, and various volume-area scaling approaches using Shuttle Radar Topography Mission surface topography of each individual glacier. We generate mass balance-altitude relations for all the glaciers by region using nearest available glacier measurements. Two method are used to model the Equilibrium line altitude (ELA) variation. One is to use ELA sensitivities to temperature and precipitation change vary by region based on the relative importance of sublimation and melting processes. The other is solved ELA implicitly for every year using the temperature at ELA and Degree Day model. We project total glacier area loss in high mountain Asia in 2050 to be 22% of their extent in 2000, and they will contribute 5-8 mm to global sea level rise.

  17. Cerebral vasoreactivity in Andeans and headache at sea level.

    PubMed

    Appenzeller, O; Passino, C; Roach, R; Gamboa, J; Gamboa, A; Bernardi, L; Bonfichi, M; Malcovati, L

    2004-04-15

    Headache is common in Cerro de Pasco (CP), Peru (altitude 4338 m) and was present in all patients with chronic mountain sickness (CMS) in CP reported here. Forty-seven percent of inhabitants report headache. Twenty-four percent of men have migraine with aura, with an average of 65 attacks a year. We assessed vasoreactivity of the cerebral vessels to CO2 by rebreathing and to NO by the administration of isosorbite dinitrate (IDN), a nitric oxide (NO) donor, using transcranial Doppler ultrasound in the middle cerebral artery (MCA) in natives of CP, some of whom suffered from CMS. We repeated the measurements in Lima (altitude 150 m) in the same subjects within 24 h of arrival. Vasodilatation in the middle cerebral artery supply territory in response to CO2 and NO, both physiologic vasodilators, is defective in Andean natives at altitude and in the same subjects at sea level. Incapacitating migraine can occur with impaired cerebral vasoreactivity to physiologic vasodilators. We propose that susceptibility to migraine might depend in part on gene expression with consequent alterations of endothelial function.

  18. 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.

  19. Implications of Sea Level Rise on Coastal Flood Hazards

    NASA Astrophysics Data System (ADS)

    Roeber, V.; Li, N.; Cheung, K.; Lane, P.; Evans, R. L.; Donnelly, J. P.; Ashton, A. D.

    2012-12-01

    Recent global and local projections suggest the sea level will be on the order of 1 m or higher than the current level by the end of the century. Coastal communities and ecosystems in low-lying areas are vulnerable to impacts resulting from hurricane or large swell events in combination with sea-level rise. This study presents the implementation and results of an integrated numerical modeling package to delineate coastal inundation due to storm landfalls at future sea levels. The modeling package utilizes a suite of numerical models to capture both large-scale phenomena in the open ocean and small-scale processes in coastal areas. It contains four components to simulate (1) meteorological conditions, (2) astronomical tides and surge, (3) wave generation, propagation, and nearshore transformation, and (4) surf-zone processes and inundation onto dry land associated with a storm event. Important aspects of this package are the two-way coupling of a spectral wave model and a storm surge model as well as a detailed representation of surf and swash zone dynamics by a higher-order Boussinesq-type wave model. The package was validated with field data from Hurricane Ivan of 2005 on the US Gulf coast and applied to tropical and extratropical storm scenarios respectively at Eglin, Florida and Camp Lejeune, North Carolina. The results show a nonlinear increase of storm surge level and nearshore wave energy with a rising sea level. The exacerbated flood hazard can have major consequences for coastal communities with respect to erosion and damage to infrastructure.

  20. 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.

  1. Late Holocene sea level variability and Atlantic Meridional Overturning Circulation

    USGS Publications Warehouse

    Cronin, Thomas M.; Farmer, Jesse R.; Marzen, R. E.; Thomas, E.; Varekamp, J.C.

    2014-01-01

    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. 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

  3. 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.

  4. 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

  5. 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.

  6. Holocene changes in sea level: evidence in micronesia.

    PubMed

    Shepard, F P; Curray, J R; Newman, W A; Bloom, A L; Newell, N D; Tracey, J I; Veeh, H H

    1967-08-01

    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 reefflat 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.

  7. The Impacts of Sea Level Rise on California's Coast

    NASA Astrophysics Data System (ADS)

    Gleick, P.; Heberger, M.; Cooley, H.

    2008-12-01

    Climate change will have a wide range of impacts on California, but among the most severe will be the implications of sea level rise for coastal ecosystems, developments, and human populations. As part of a comprehensive set of studies done for the State of California, we present here the results of a detailed analysis of the risks of climate-induced sea-level rise for economic structures, populations, and natural ecosystems. Using a combination of high-resolution digital mapping and data sets of the value and type of property and land uses, we develop quantitative estimates of the value of property at risk of inundation over the next century under different sea-level rise scenarios. We also evaluate the number of people at risk of flooding, among other indices of vulnerability. The final phase of the project also looks at the costs of building different levels of coastal protection. The approaches developed here can be applied in any coastal region, but our assessment also points out the need for improvements in data collection and mapping.

  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.; 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. 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.

  10. 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.

  11. 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.

  12. Time series analysis of Cenozoic era sea level and paleotemperature data

    USGS Publications Warehouse

    Rosenfield, George H.; Huffman, Tod E.

    1983-01-01

    A statistical analysis of Cenozoic era sea level and paleotemperature data was performed to determine the cycles of each data set and the correspondence between them. Accordingly, each of the four time series were first analyzed independently in the univariate mode of a spectral analysis. The two basic data sets were then analyzed in a paired cross-spectral analysis. The prominent periodic cycles remaining in the data sets after linear trend removal, were: sea level surface from seismic stratigraphy--9.6 million years, updated version of sea level surface from seismic stratigraphy--9.5 million years, continental paleotemperatures from paleobotanical interpretations--9.6 million years, and marine paleotemperatures from foraminiferal isotopic data--12.7 million years. The cross-correlation properties between the data sets of continental paleotemperatures from paleobotanical interpretations and sea level surface from seismic stratigraphy at the common prominent period of 9.6 million years were: (1) The squared coherency value which measures cross correlation between the two data sets has the value 0.30, and (2) the amount by which the continental paleotemperatures from paleobotanical interpretations data lags the sea level surface from seismic stratigraphy data is 2.70 million years.

  13. 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

    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

  14. Late- and Postglacial Sea-Level Change and Paleoenvironments in the Oder Estuary, Southern Baltic Sea

    NASA Astrophysics Data System (ADS)

    Müller, Anne

    2001-01-01

    Knowledge of sea-level change in the southern Baltic Sea region is important for understanding the variations in late Pleistocene and Holocene sea-level change across northern Europe. These variations are a consequence of the response of the Earth's crust to the deglaciation of Fennoscandia and of the water added to the oceans from the melting of all Pleistocene ice sheets. The sedimentological and geochemical composition of five sediment cores from the lagoonal Oder Estuary offers new observational evidence for sea-level change and coastal development in the southern Baltic Sea region. The combined use of several geochemical proxies (organic carbon, nitrogen, calcium carbonate and biogenic opal contents, Corg/S and Corg/N ratios, δ13C values of organic matter, and δ15N values) is a new approach for the study area. The chemical evidence of this multiproxy approach allows clear identification of several stages in the development of the lagoonal environment: postglacial lake stages with sandy sedimentation during the Older Dryas and the Allerød stades, lacustrine phases with high autochthonous productivity during the Atlantic stade, terrestrial stages with peat formation at the beginning of the Subboreal stade, sedimentation as a result of marine transgression, and brackish sedimentation after the formation of sand spits and barrier islands during the Subatlantic stade. The stages are the result of regional sea-level change owing to complex shoreline development. They support the tentative sea-level curve proposed nearly 20 years ago for the region. In addition, changes in Oder River input in response to climate conditions is monitored. Whereas high terrigenous input of organic matter from the Oder River occurred during periods of humid climate during the Allerød, Atlantic, and Subatlantic stades, Oder River discharge decreased with drier and cooler climate conditions during the Subboreal stade. Furthermore, the geochemical evidence points to local anomalies such

  15. 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

  16. Meteotsunami-tide interactions and high-frequency sea level oscillations in the eastern Yellow Sea

    NASA Astrophysics Data System (ADS)

    Choi, Byoung-Ju; Hwang, Chorong; Lee, Sang-Ho

    2014-10-01

    While an air pressure jump was moving southeastward over the shallow water region of the eastern Yellow Sea in March 2007, a long ocean wave (meteotsunami) was generated and amplified due to the Proudman resonance. The long wave arrived at the coast during high tide with wave amplitude of 1.4 m and seawater overflew seawalls and inundated the land. High-frequency sea level oscillations continued for 8-9 h after the long wave hit a local coast. The Moon's age was 12 days, and the tidal range was about 4 m between neap and spring tides. Two-dimensional numerical simulations were performed, to reproduce amplification of the long ocean wave in offshore and oscillations of sea level at the coast. Both tidal elevation and tidal currents were found to affect the growth of the long wave amplitude by the interactions between tides and the long wave. Long wave-tides interactions are important processes for the accurate prediction of long wave arrival time and maximum height and for the reduction of coastal hazards in the macrotidal region. After the long wave hit the coast of remote regions, reflected waves propagated radially from remote regions to a local coast. The high-frequency sea level oscillations at a local observation station continued, until all of the reflected waves from remote regions had passed by. It was concluded that high-frequency oscillations of sea level are generated not only by local reflection of the long wave, but also by propagation of the reflected waves from remote regions.

  17. 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

  18. 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…

  19. Is the detection of accelerated sea level rise imminent?

    PubMed Central

    Fasullo, J. T.; Nerem, R. S.; Hamlington, B.

    2016-01-01

    Global mean sea level rise estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time. In stark contrast to this expectation however, current altimeter products show the rate of sea level rise to have decreased from the first to second decades of the altimeter era. Here, a combined analysis of altimeter data and specially designed climate model simulations shows the 1991 eruption of Mt Pinatubo to likely have masked the acceleration that would have otherwise occurred. This masking arose largely from a recovery in ocean heat content through the mid to late 1990 s subsequent to major heat content reductions in the years following the eruption. A consequence of this finding is that barring another major volcanic eruption, a detectable acceleration is likely to emerge from the noise of internal climate variability in the coming decade. PMID:27506974

  20. 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.

  1. Control of Quaternary sea-level changes on gas seeps

    NASA Astrophysics Data System (ADS)

    Riboulot, Vincent; Thomas, Yannick; Berné, Serge; Jouet, Gwénaël.; Cattaneo, Antonio

    2014-07-01

    Gas seeping to the seafloor through structures such as pockmarks may contribute significantly to the enrichment of atmospheric greenhouse gases and global warming. Gas seeps in the Gulf of Lions, Western Mediterranean, are cyclical, and pockmark "life" is governed both by sediment accumulation on the continental margin and Quaternary climate changes. Three-dimensional seismic data, correlated to multi-proxy analysis of a deep borehole, have shown that these pockmarks are associated with oblique chimneys. The prograding chimney geometry demonstrates the syn-sedimentary and long-lasting functioning of the gas seeps. Gas chimneys have reworked chronologically constrained stratigraphic units and have functioned episodically, with maximum activity around sea level lowstands. Therefore, we argue that one of the main driving mechanisms responsible for their formation is the variation in hydrostatic pressure driven by relative sea level changes.

  2. 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.

  3. 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.

  4. Is the detection of accelerated sea level rise imminent?

    NASA Astrophysics Data System (ADS)

    Fasullo, J. T.; Nerem, R. S.; Hamlington, B.

    2016-08-01

    Global mean sea level rise estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time. In stark contrast to this expectation however, current altimeter products show the rate of sea level rise to have decreased from the first to second decades of the altimeter era. Here, a combined analysis of altimeter data and specially designed climate model simulations shows the 1991 eruption of Mt Pinatubo to likely have masked the acceleration that would have otherwise occurred. This masking arose largely from a recovery in ocean heat content through the mid to late 1990 s subsequent to major heat content reductions in the years following the eruption. A consequence of this finding is that barring another major volcanic eruption, a detectable acceleration is likely to emerge from the noise of internal climate variability in the coming decade.

  5. Is the detection of accelerated sea level rise imminent?

    PubMed

    Fasullo, J T; Nerem, R S; Hamlington, B

    2016-08-10

    Global mean sea level rise estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time. In stark contrast to this expectation however, current altimeter products show the rate of sea level rise to have decreased from the first to second decades of the altimeter era. Here, a combined analysis of altimeter data and specially designed climate model simulations shows the 1991 eruption of Mt Pinatubo to likely have masked the acceleration that would have otherwise occurred. This masking arose largely from a recovery in ocean heat content through the mid to late 1990 s subsequent to major heat content reductions in the years following the eruption. A consequence of this finding is that barring another major volcanic eruption, a detectable acceleration is likely to emerge from the noise of internal climate variability in the coming decade.

  6. Relative sea levels from tide-gauge records

    PubMed Central

    Emery, K. O.

    1980-01-01

    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. Images PMID:16592929

  7. Topex-Poseidon analysis of sea level variability over the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Catalan P-U, M.; Villares, P.; Catalan, M.; Gomez-Enri, J.

    2003-04-01

    The variability of sea level and surface geostrophic currents in Atlantic Ocean is investigated using 333 cycles of altimeter information obtained by TOPEX-POSEIDON satellite. After the improvements of orbit accuracy, the most important concern to studies of sea level variability from altimeter height data are related with the formalism used for modelling the altimetric measurement corrections. Presently, one of the main sources of potential error is the correction for atmospheric pressure loading, the so-called ‘inverse barometer effect’. As is well known, this correction is intended to adjust the sea surface elevation for the static effects of the downward force of the mass of the atmosphere on the sea surface, adjusted, in this oversimplified model in 1cm/mbar. The exact response of the sea surface to atmospheric pressure loading depends on the space and time scales of the pressure field and must be specially a concern at high latitudes where atmospheric pressure fluctuations are large due to the intensity of low pressure fields at these latitudes and the additional uncertainty in the model estimates of the local sea level pressure. To study these effects over the whole Atlantic Ocean we compute a linear regression adjustment and an Empirical Orthogonal Functions Decomposition (EOFD), between sea level variation without inverse barometer correction and the atmospheric pressure, in all the Topex-Poseidon cross points over the whole Atlantic, including both the Artic and Antarctic Oceans. We use the barometric factor computed from the linear regression to correct the satellite mean sea level variation, comparing the correlation with the pressure. Our results show an important improvement in the decorrelation between sea level and atmospheric pressure time series, compared with the use of Inverse Barometer model, at most of the satellite cross points. The complicated nature of sea level variability at high latitudes justify that EOFD analysis conclusions

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  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. 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.

  15. 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.

  16. 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.

  17. 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.

  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. 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.

  20. Detection of human influence on sea-level pressure.

    PubMed

    Gillett, Nathan P; Zwiers, Francis W; Weaver, Andrew J; Stott, Peter A

    2003-03-20

    Greenhouse gases and tropospheric sulphate aerosols--the main human influences on climate--have been shown to have had a detectable effect on surface air temperature, the temperature of the free troposphere and stratosphere and ocean temperature. Nevertheless, the question remains as to whether human influence is detectable in any variable other than temperature. Here we detect an influence of anthropogenic greenhouse gases and sulphate aerosols in observations of winter sea-level pressure (December to February), using combined simulations from four climate models. We find increases in sea-level pressure over the subtropical North Atlantic Ocean, southern Europe and North Africa, and decreases in the polar regions and the North Pacific Ocean, in response to human influence. Our analysis also indicates that the climate models substantially underestimate the magnitude of the sea-level pressure response. This discrepancy suggests that the upward trend in the North Atlantic Oscillation index (corresponding to strengthened westerlies in the North Atlantic region), as simulated in a number of global warming scenarios, may be too small, leading to an underestimation of the impacts of anthropogenic climate change on European climate.

  1. How mangrove forests adjust to rising sea level.

    PubMed

    Krauss, Ken W; McKee, Karen L; Lovelock, Catherine E; Cahoon, Donald R; Saintilan, Neil; Reef, Ruth; Chen, Luzhen

    2014-04-01

    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.

  2. 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.

  3. 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 Y.

    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

  4. Holocene Relative Sea-Level Changes from the us Atlantic Coast

    NASA Astrophysics Data System (ADS)

    Horton, B.; Engelhart, S. E.; Kemp, A.; Hill, D. F.; Kopp, R. E.

    2013-12-01

    Reconstructions of Holocene relative sea level (RSL) are important for identifying the ice equivalent meltwater contribution to sea-level change during deglaciation and constraining Earth-Ice models of Glacial Isostatic Adjustment. RSL reconstructions provide data for estimating rates of spatially variable and ongoing vertical land motion; a requirement for understanding the variation in modern and late Holocene sea level as recorded by instrumental and proxy records. We explain the methodology employed to reconstruct former sea levels (as laid out by the International Geoscience Programme) and produce sea level index points from the U.S. Atlantic coast. Sea-level index points consist of an estimate of X (age) and Y (the position of former RSL). Where a suite of index points are developed for a locality or region, they describe changes in RSL through time and estimate rates of change. A valid index point must meet the following four criteria: (1) location of the sample is known to within 1 km; (2) the altitude of the sample (and the error associated with measuring that altitude) is known; (3) the indicative meaning and range is estimated; and (4) the age of the sample is calibrated to sidereal years using the latest calibration curves. By applying this standardized approach to existing literature and new samples, a database of 500 sea-level index points was generated for the U.S. Atlantic coast. The data include discrete RSL reconstructions from individual core samples and continuous records of recent (approximately last 3000 years) RSL using ordered samples from a single core of salt-marsh sediment. We corrected the index points for the influence of compaction and paleotidal range changes. The database is sub-divided into 16 regions based on the distance from the Laurentide Ice Sheet and availability of data. We used a spatio-temporal Gaussian process model to identify and characterize persistent phases of sea-level behavior and to estimate rates and sources of

  5. 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.

  6. Estimating decadal variability in sea level from tide gauge records: an application to the North Sea.

    NASA Astrophysics Data System (ADS)

    Riva, R.; Frederikse, T.; Slobbe, C.; Broerse, T.; Verlaan, M.

    2015-12-01

    One of the primary observational datasets of sea level is represented by the tide gauge record. We propose a new method to estimate trends and 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 variance 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. Explaining variability significantly improves the accuracy of the found decadal variability signal, where the best results are obtained with the hydrodynamic model. We find a consistent decadal sea level signal in the North Sea, which significantly influences estimates of a linear trend over the 34-year period.

  7. The Influence of the Terrestrial Reference Frame on Studies of Sea Level Change

    NASA Astrophysics Data System (ADS)

    Nerem, R. S.; Bar-Sever, Y. E.; Haines, B. J.; Desai, S.; Heflin, M. B.

    2015-12-01

    The terrestrial reference frame (TRF) provides the foundation for the accurate monitoring of sea level using both ground-based (tide gauges) and space-based (satellite altimetry) techniques. For the latter, tide gauges are also used to monitor drifts in the satellite instruments over time. The accuracy of the terrestrial reference frame (TRF) is thus a critical component for both types of sea level measurements. The TRF is central to the formation of geocentric sea-surface height (SSH) measurements from satellite altimeter data. The computed satellite orbits are linked to a particular TRF via the assumed locations of the ground-based tracking systems. The manner in which TRF errors are expressed in the orbit solution (and thus SSH) is not straightforward, and depends on the models of the forces underlying the satellite's motion. We discuss this relationship, and provide examples of the systematic TRF-induced errors in the altimeter derived sea-level record. The TRF is also crucial to the interpretation of tide-gauge measurements, as it enables the separation of vertical land motion from volumetric changes in the water level. TRF errors affect tide gauge measurements through GNSS estimates of the vertical land motion at each tide gauge. This talk will discuss the current accuracy of the TRF and how errors in the TRF impact both satellite altimeter and tide gauge sea level measurements. We will also discuss simulations of how the proposed Geodetic Reference Antenna in SPace (GRASP) satellite mission could reduce these errors and revolutionize how reference frames are computed in general.

  8. Controls on Precambrian sea level change and sedimentary cyclicity

    NASA Astrophysics Data System (ADS)

    Eriksson, P. G.; Catuneanu, O.; Nelson, D. R.; Popa, M.

    2005-04-01

    Although uniformitarianism applies in a general sense to the controls on relative and global sea level change, some influences thereon were more prominent in the Precambrian. Short-term base level change due to waves and tides may have been enhanced due to possibly more uniform circulation systems on wide, low gradient Precambrian shelves. The lack of evidence for global glacial events in the Precambrian record implies that intraplate stresses and cyclic changes to Earth's geoid were more likely explanations for third-order sea level change than glacio-eustasy. Higher heat flow in the earlier Precambrian may have led to more rapid tectonic plate formation, transport and destruction, along with an increased role for hot spots, aseismic ridges and mantle plumes (superplumes), all of which may have influenced cyclic sedimentation within the ocean basins. A weak cyclicity in the occurrence of plume events has an approximate duration comparable to that of first-order (supercontinental cycle) sea level change. Second-order cyclicity in the Precambrian largely reflects the influences of thermal epeirogeny, changes to mid-ocean ridge volume as well as to ridge growth and decay rates, and cratonic marginal downwarping concomitant with either sediment loading or extensional tectonism. Third-order cycles of sea level change in the Precambrian also reflected cyclic loading/unloading within flexural foreland basin settings, and filling/deflation of magma chambers associated with island arc evolution. The relatively limited number of studies of Precambrian sequence stratigraphy allows some preliminary conclusions to be drawn on duration of the first three orders of cyclicity. Archaean greenstone basins appear to have had first- and second-order cycle durations analogous to Phanerozoic equivalents, supporting steady state tectonics throughout Earth history. In direct contrast, however, preserved basin-fills from Neoarchaean-Palaeoproterozoic cratonic terranes have first- and

  9. Air-Sea Interaction Measurements from the Controlled Towed Vehicle

    NASA Astrophysics Data System (ADS)

    Khelif, D.; Bluth, R. T.; Jonsson, H.; Barge, J.

    2014-12-01

    The Controlled Towed Vehicle (CTV) uses improved towed drone technology to actively maintain via a radar altimeter and controllable wing a user-set height that can be as low as the canonical reference height of 10 m above the sea surface. After take-off, the drone is released from the tow aircraft on a ~700-m stainless steel cable. We have instrumented the 0.23 m diameter and 2.13 m long drone with high fidelity instruments to measure the means and turbulent fluctuations of 3-D wind vector, temperature, humidity, pressure, CO2 and IR sea surface temperature. Data are recorded internally at 40 Hz and simultaneously transmitted to the tow aircraft via dedicated wireless Ethernet link. The CTV accommodates 40 kg of instrument payload and provides it with 250 W of continuous power through a ram air propeller-driven generator. Therefore its endurance is only limited by that of the tow aircraft.We will discuss the CTV development, the engineering challenges and solutions that have been successfully implemented to overcome them. We present results from recent flights as low as 9 m over the coastal ocean and comparisons of profiles and turbulent fluxes from the CTV and the tow aircraft. Manned aircraft operation at low-level boundary-layer flights is very limited. Dropsondes and UAS (Unmanned Aerial Systems) and UAS are alternates for measurements near the ocean surface. However, dropsondes have limited sensor capability and do not measure fluxes, and most present UAS vehicles do not have the payload and power capacity nor the low-flying ability in high winds over the oceans. The CTV therefore, fills a needed gap between the dropsondes, in situ aircraft, and UAS. The payload, capacity and power of the CTV makes it suitable for a variety of atmospheric research measurements. Other sensors to measure aerosol, chemistry, radiation, etc., could be readily accommodated in the CTV.

  10. 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

  11. 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

    .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.

  12. Simultaneous measurements of skin sea surface temperature and sea surface emissivity from a single thermal imagery.

    PubMed

    Yoshimori, Kyu; Tamba, Sumio; Yokoyama, Ryuzo

    2002-08-20

    A novel method, to our knowledge, to measure simultaneously the thermal emissivity and skin temperature of a sea surface has been developed. The proposed method uses an infrared image that includes a sea surface and a reference object located near the surface. By combining this image with sky radiation temperature, we retrieve both skin sea surface temperature and sea surface emissivity from the single infrared image. Because the method requires no knowledge of thermal radiative properties of actual sea surfaces, it can be used even for a contaminated sea surface whose emissivity is hard to determine theoretically, e.g., oil slicks or slicks produced by biological wastes. Experimental results demonstrate that the estimated emissivity agrees with the theoretical prediction and, also, the recovered temperature distribution of skin sea surface has no appreciable high-temperature area that is due to reflection of the reference object. The method allows the acquisition of match-up data of radiometric sea surface temperatures that precisely correspond to the satellite observable data.

  13. The sea state bias in altimeter estimates of sea level from collinear analysis of TOPEX data

    NASA Technical Reports Server (NTRS)

    Chelton, Dudley B.

    1994-01-01

    The wind speed and significant wave height (H(sub 1/3)) dependencies of the sea state bias in altimeter estimates of sea level, expressed in the form (Delta)h(sub SSB) = bH(sub 1/3), are examined from least squares analysis of 21 cycles of collinear TOPEX data. The bias coefficient b is found to increase in magnitude with increasing wind speed up to about 12 m/s and decrease monotonically in magnitude with increasing H(sub 1/3). A parameterization of b as a quadratic function of wind speed only, as in the formation used to produce the TOPEX geophysical data records (GDRs), is significantly better than a parameterization purely in terms of H(sub 1/3). However, a four-parameter combined wind speed and wave height formulation for b (quadratic in wind speed plus linear in H(sub 1/3)) significantly improves the accuracy of the sea state bias correction. The GDR formulation in terms of wind speed only should therefore be expanded to account for a wave height dependence of b. An attempt to quantify the accuracy of the sea state bias correction (Delta)h(sub SSB) concludes that the uncertainty is a disconcertingly large 1% of H(sub 1/3).

  14. Tidal marshes as disequilibrium landscapes? Lags between morphology and Holocene sea level change

    USGS Publications Warehouse

    Kirwan, M.L.; Murray, A.B.

    2008-01-01

    Historical acceleration in the rate of global sea level rise and recent observations of marsh degradation highlight the importance of understanding how marshes respond to sea level change. Here, we use an existing numerical model to demonstrate that marsh morphology, and its effect on biological productivity and vertical accretion, could lag century-scale sea level rise rate oscillations by several decades. This suggests that marshes, and perhaps other intertidal environments, have not been in equilibrium with Holocene sea level. Additional results suggest that marshes have not yet fully responded to historical sea level acceleration. Consequently, marshes today may be out of equilibrium with modern rates of sea level rise, and further adjustment in the form of platform deepening and channel erosion could be expected. Under an accelerating sea level rise rate, the morphology and productivity of marshland will reflect environmental conditions of the past, and studies of marshes today will underestimate their response to sea level rise.

  15. Atmospheric oxygen 18 and sea-level changes

    NASA Astrophysics Data System (ADS)

    Jouzel, Jean; Hoffmann, Georg; Parrenin, Frédéric; Waelbroeck, Claire

    2002-01-01

    Past isotopic composition of atmospheric oxygen (δ 18O atm) can be inferred from the analysis of air bubbles trapped in ice caps. The longest record covers the last 420 ka (thousand of years) at the Vostok site in East Antarctica. It shows a strong modulation by the precession and striking similarities, but also noticeable differences, with the deep-sea core oxygen 18 record from which changes in the oxygen content of sea-water (δ 18O sw) and in sea-level can be derived. Indeed, δ 18O atm is driven by complex fractionation processes occuring during respiration and photosynthesis. Both δ 18O atm and its difference with respect to δ 18O sw (the Dole effect) are influenced by factors such as the ratio of oceanic and terrestrial productivities which may have significantly changed between different climates. Also, the response time of δ 18O atm to oceanic changes should be taken in consideration but this parameter itself depends on biospheric activity. We review the various aspects of the link between the δ 18O atm and the δ 18O sw signals. We also examine the approach followed by Shackleton (Science (2000)) for deriving sea-level change from the δ 18O atm Vostok record, assuming that the phase between this record and insolation changes is constant and that the Dole effect is a fraction of the precessional component of the δ 18O atm signal. Glaciological constraints on the Vostok chronology and the complexity of the Dole effect show that those two assumptions are quite probably too simplistic.

  16. Risk factor analysis for sea lice, Caligus rogercresseyi, levels in farmed salmonids in southern Chile.

    PubMed

    Yatabe, T; Arriagada, G; Hamilton-West, C; Urcelay, S

    2011-05-01

    Sea lice, Caligus rogercresseyi, are ectoparasitic copepods, which severely affect the salmon farming industry in southern Chile, reducing the health status of fish and producing both direct and indirect economic losses. Local farmers have reported increasing infestation levels since 2004, reaching a peak in 2007. In response to this situation, the Chilean Fisheries Service (Sernapesca) developed a surveillance programme; the first step of which consisted of a general survey of salmon farms. This survey included documenting counts of parasite burdens on fish and measurements of several husbandry and environmental factors providing an evaluation of risk factors for the observed infestation levels. The information collected was analysed using a linear mixed model technique, which takes into account the clustered structure of data, decomposing the unexplained variation and assigning it to different aggregation levels of the productive system. Geographical zones, fish species, treatment against sea lice performed 1 month before sampling, stocking density, fish weight and water salinity were the variables significantly associated with sea lice burdens. In contrast, treatments performed 2-3 months before sampling, use of photoperiod in sea cages and water temperature, were not significant. There was significant unexplained variation at all aggregation levels, i.e. sub-zone, fish farm and cage level, with the fish farm level showing the greatest variation. PMID:21488904

  17. Land subsidence and relative sea-level rise in the southern Chesapeake Bay region

    USGS Publications Warehouse

    Eggleston, Jack; Pope, Jason

    2013-01-01

    The southern Chesapeake Bay region is experiencing land subsidence and rising water levels due to global sea-level rise; land subsidence and rising water levels combine to cause relative sea-level rise. Land subsidence has been observed since the 1940s in the southern Chesapeake Bay region at rates of 1.1 to 4.8 millimeters per year (mm/yr), and subsidence continues today. This land subsidence helps explain why the region has the highest rates of sea-level rise on the Atlantic Coast of the United States. Data indicate that land subsidence has been responsible for more than half the relative sea-level rise measured in the region. Land subsidence increases the risk of flooding in low-lying areas, which in turn has important economic, environmental, and human health consequences for the heavily populated and ecologically important southern Chesapeake Bay region. The aquifer system in the region has been compacted by extensive groundwater pumping in the region at rates of 1.5- to 3.7-mm/yr; this compaction accounts for more than half of observed land subsidence in the region. Glacial isostatic adjustment, or the flexing of the Earth’s crust in response to glacier formation and melting, also likely contributes to land subsidence in the region.

  18. Recent contributions of glaciers and ice caps to sea level rise.

    PubMed

    Jacob, Thomas; Wahr, John; Pfeffer, W Tad; Swenson, Sean

    2012-02-08

    Glaciers and ice caps (GICs) are important contributors to present-day global mean sea level rise. Most previous global mass balance estimates for GICs rely on extrapolation of sparse mass balance measurements representing only a small fraction of the GIC area, leaving their overall contribution to sea level rise unclear. Here we show that GICs, excluding the Greenland and Antarctic peripheral GICs, lost mass at a rate of 148 ± 30 Gt yr(-1) from January 2003 to December 2010, contributing 0.41 ± 0.08 mm yr(-1) to sea level rise. Our results are based on a global, simultaneous inversion of monthly GRACE-derived satellite gravity fields, from which we calculate the mass change over all ice-covered regions greater in area than 100 km(2). The GIC rate for 2003-2010 is about 30 per cent smaller than the previous mass balance estimate that most closely matches our study period. The high mountains of Asia, in particular, show a mass loss of only 4 ± 20 Gt yr(-1) for 2003-2010, compared with 47-55 Gt yr(-1) in previously published estimates. For completeness, we also estimate that the Greenland and Antarctic ice sheets, including their peripheral GICs, contributed 1.06 ± 0.19 mm yr(-1) to sea level rise over the same time period. The total contribution to sea level rise from all ice-covered regions is thus 1.48 ± 0.26 mm (-1), which agrees well with independent estimates of sea level rise originating from land ice loss and other terrestrial sources.

  19. Sea level, dinosaur diversity and sampling biases: investigating the 'common cause' hypothesis in the terrestrial realm.

    PubMed

    Butler, Richard J; Benson, Roger B J; Carrano, Matthew T; Mannion, Philip D; Upchurch, Paul

    2011-04-22

    The fossil record is our primary window onto the diversification of ancient life, but there are widespread concerns that sampling biases may distort observed palaeodiversity counts. Such concerns have been reinforced by numerous studies that found correlations between measures of sampling intensity and observed diversity. However, correlation does not necessarily mean that sampling controls observed diversity: an alternative view is that both sampling and diversity may be driven by some common factor (e.g. variation in continental flooding driven by sea level). The latter is known as the 'common cause' hypothesis. Here, we present quantitative analyses of the relationships between dinosaur diversity, sampling of the dinosaur fossil record, and changes in continental flooding and sea level, providing new insights into terrestrial common cause. Although raw data show significant correlations between continental flooding/sea level and both observed diversity and sampling, these correlations do not survive detrending or removal of short-term autocorrelation. By contrast, the strong correlation between diversity and sampling is robust to various data transformations. Correlations between continental flooding/sea level and taxic diversity/sampling result from a shared upward trend in all data series, and short-term changes in continental flooding/sea level and diversity/sampling do not correlate. The hypothesis that global dinosaur diversity is tied to sea-level fluctuations is poorly supported, and terrestrial common cause is unsubstantiated as currently conceived. Instead, we consider variation in sampling to be the preferred null hypothesis for short-term diversity variation in the Mesozoic terrestrial realm.

  20. Modeling Sea-Level Change using Errors-in-Variables Integrated Gaussian Processes

    NASA Astrophysics Data System (ADS)

    Cahill, Niamh; Parnell, Andrew; Kemp, Andrew; Horton, Benjamin

    2014-05-01

    We perform Bayesian inference on historical and late Holocene (last 2000 years) rates of sea-level change. The data that form the input to our model are tide-gauge measurements and proxy reconstructions from cores of coastal sediment. To accurately estimate rates of sea-level change and reliably compare tide-gauge compilations with proxy reconstructions it is necessary to account for the uncertainties that characterize each dataset. Many previous studies used simple linear regression models (most commonly polynomial regression) resulting in overly precise rate estimates. The model we propose uses an integrated Gaussian process approach, where a Gaussian process prior is placed on the rate of sea-level change and the data itself is modeled as the integral of this rate process. The non-parametric Gaussian process model is known to be well suited to modeling time series data. The advantage of using an integrated Gaussian process is that it allows for the direct estimation of the derivative of a one dimensional curve. The derivative at a particular time point will be representative of the rate of sea level change at that time point. The tide gauge and proxy data are complicated by multiple sources of uncertainty, some of which arise as part of the data collection exercise. Most notably, the proxy reconstructions include temporal uncertainty from dating of the sediment core using techniques such as radiocarbon. As a result of this, the integrated Gaussian process model is set in an errors-in-variables (EIV) framework so as to take account of this temporal uncertainty. The data must be corrected for land-level change known as glacio-isostatic adjustment (GIA) as it is important to isolate the climate-related sea-level signal. The correction for GIA introduces covariance between individual age and sea level observations into the model. The proposed integrated Gaussian process model allows for the estimation of instantaneous rates of sea-level change and accounts for all

  1. X-33 XRS-2200 Linear Aerospike Engine Sea Level Plume Radiation

    NASA Technical Reports Server (NTRS)

    DAgostino, Mark G.; Lee, Young C.; Wang, Ten-See; Turner, Jim (Technical Monitor)

    2001-01-01

    Wide band plume radiation data were collected during ten sea level tests of a single XRS-2200 engine at the NASA Stennis Space Center in 1999 and 2000. The XRS-2200 is a liquid hydrogen/liquid oxygen fueled, gas generator cycle linear aerospike engine which develops 204,420 lbf thrust at sea level. Instrumentation consisted of six hemispherical radiometers and one narrow view radiometer. Test conditions varied from 100% to 57% power level (PL) and 6.0 to 4.5 oxidizer to fuel (O/F) ratio. Measured radiation rates generally increased with engine chamber pressure and mixture ratio. One hundred percent power level radiation data were compared to predictions made with the FDNS and GASRAD codes. Predicted levels ranged from 42% over to 7% under average test values.

  2. 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

  3. Correlation of sea level falls interpreted from atoll stratigraphy with turbidites in adjacent basins

    SciTech Connect

    Lincoln, J.M. )

    1990-05-01

    Past sea levels can be derived from any atoll subsurface sediments deposited at or near sea level by determining the ages of deposition and correcting the present depths to the sediments for subsidence of the underlying edifice since the times of deposition. A sea level curve constructed by this method consists of discontinuous segments, each corresponding to a period of rising relative sea level and deposition of a discrete sedimentary package. Discontinuities in the sea level curve derived by this method correspond to relative sea level falls and stratigraphic hiatuses in the atoll subsurface. During intervals of relative sea level fall an atoll emerges to become a high limestone island. Sea level may fluctuate several times during a period of atoll emergence to become a high limestone island. Sea level may fluctuate several times during a period of atoll emergence without depositing sediments on top of the atoll. Furthermore, subaerial erosion may remove a substantial part of the depositional record of previous sea level fluctuations. For these reasons the authors must look to the adjacent basins to complement the incomplete record of sea level change recorded beneath atolls. During lowstands of sea level, faunas originally deposited near sea