Science.gov

Sample records for alkenone sea surface

  1. Sea surface temperature proxies (alkenones, foraminiferal Mg/Ca, and planktonic foraminiferal assemblage) and their implications in the Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Kim, Ryoung Ah; Lee, Kyung Eun; Bae, Si Woong

    2015-12-01

    We reviewed three sea surface temperature (SST) proxies in the Okinawa Trough (OT): alkenones, planktonic foraminiferal Mg/Ca, and planktonic foraminiferal assemblages. The seasonal and vertical distribution patterns of each proxy-related organism in the water column were reviewed to confirm the applicability of each proxy. In addition, current SSTs (Japan Oceanographic Data Center dataset from 1906 to 2003) were compared with core-top sediment temperatures reconstructed using the proxies. Temperatures calculated using the alkenone unsaturation index represent annual mean SSTs, and temperatures calculated using Mg/Ca of Globigerinoides ruber capture summer to autumn (June-November) SSTs. Core-top August SSTs calculated from planktonic foraminiferal assemblages corresponded well with the observed SSTs, but core-top February temperatures were ~3.6 °C warmer than the observed SSTs. SST proxy estimates from marine sediments dating back to the late Holocene (0-3 cal ky BP) and the last glacial maximum (18-21 cal ky BP) were compared. Comparisons between proxy SST estimates show that foraminiferal assemblage-based August SSTs were the warmest. Alkenone-based temperature estimates were lower than Mg/Ca-based temperature estimates, probably because the alkenone-based temperature represents the annual mean temperature, whereas the Mg/Ca-based temperature represents the summer-autumn mean temperature. February assemblage SSTs seem to be greatly affected by the statistical technique and/or database used. These results suggest that seasonality should be considered in past SST reconstruction using alkenone and Mg/Ca in the OT. The planktonic foraminiferal assemblage technique does not appear to be promising with respect to accurately reconstructing past SSTs (especially winter) in the OT. Habitat depth may not be an issue because both alkenone producers and G. ruber live at the upper surface mixed layer in the area.

  2. Late Pliocene Sea Surface Temperature contrast in the Benguela upwelling as recorded by foraminiferal Mg/Ca and alkenones

    NASA Astrophysics Data System (ADS)

    Leduc, G.; Garbe-Schoenberg, C.; Regenberg, M.; Schneider, R. R.

    2011-12-01

    Alkenone-based sea surface temperature (SST) in the Benguela region reveal quite warm and stable conditions between ~3.0 and 2.0 Ma, coinciding with a period of very high diatom production as revealed by mass accumulation rates (MAR) of biogenic opal (Marlow et al., 2000, Science; Etourneau et al., 2009, Geology). Such a pattern is difficult to believe with the general perception that high diatom productivity results from strong coastal upwelling associated with pronounced Surface Ocean cooling. Therefore we assessed whether different paleothermometers from the same sedimentary archive (i.e. ODP site 1082) provide different results for the Namibian upwelling system by performing a comparison between alkenone-derived temperatures and those from the planktonic foraminifera Globigerinoides bulloides, a species known to proliferate in upwelling regions. We used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for multiple in situ determination of Mg/Ca in single tests of G. bulloides. These measurements allow monitoring of contaminant phases linked to Mg-rich clays (monitored by Al/Ca) and Mn-rich foraminiferal tests, which contain substantial high Mg (monitored by Mn/Ca) (Pena et al., 2005, G-cubed). Moreover, using LA-ICP-MS measurements for Mg/Ca ratios on single specimens allows estimating the range of seasonal or vertical temperature variability by considering the intra-sample variance in the SST estimated from different specimens and/or different chambers within the same specimen. When compared to the Pliocene alkenone SST record, the Mg/Ca-ratios imply SSTs colder by ~10°C. A similar contrast in SST estimates between these two proxies was reported for the last 20 ka in the same region (Farmer et al., 2005, Paleoceanography). Such discrepancy can be reconciled by assuming that the two SST proxies are either strongly skewed towards warm (non-upwelling) and cold (upwelling) conditions for alkenones and Mg/Ca SST, respectively, or by the

  3. A closer look at the hydrogen isotopic composition of alkenones as proxy for paleo sea surface salinity.

    NASA Astrophysics Data System (ADS)

    van der Meer, Marcel; Benthien, Albert; Bijma, Jelle; Sinninghe Damste, Jaap; Schouten, Stefan

    2010-05-01

    Culture studies of Emiliania huxleyi and Gephyrocapsa oceanica grown at different salinities and different temperatures and, as a consequence, different growth rates showed that there is a strong correlation between the fractionation factor Alphaalkenones-growthwater and salinity for both E. huxleyi and G. oceanica (Schouten et al., 2006). The hydrogen isotope fractionation by these haptophyte algae predominantly depends on salinity, with less fractionation at higher salinities. Based on the results of Schouten et al., paleosalinities of the Black Sea and the Eastern Mediterranean have been reconstructed using the DeltaD of alkenones (van der Meer et al., 2007, 2008). Recently, however, there has been some debate about whether analyzing the C37 alkenones together is appropriate for reconstructing paleosalinity since there is a relatively large difference in the DeltaD of the C37:2 and C37:3 alkenones, respectively (D'Andrea et al., 2007; Schwab and Sachs 2009; Molhowe et al., 2009). To examine this potential problem we analyzed the C37:2 and C37:3 alkenones of the original Schouten et al. E. huxleyi samples separately and found an increasing difference in DeltaD between the C37:2 and C37:3 alkenone with decreasing temperature and, therefore, decreasing relative abundance of the C37:2 alkenone. This is likely caused by a process similar to Raleigh distillation as the C37:3 is formed from the initially synthesized C37:2 alkenone. These results suggested that for the purpose of reconstructing paleo SSS it might be better to analyze the C37 alkenones together rather than the separate isomers. Schouten et al 2006 showed that besides salinity, growth rate also had an effect on the hydrogen isotopic composition of C37 alkenones. To get better handle on growth rate as a controlling factor E. huxleyi was grown under different light intensities to vary growth rate but not salinity. This experiment showed that light intensity itself has a large effect on hydrogen isotope

  4. The Gephyrocapsa Sea Surface Paleothermometer Put To The Test: Comparison With Alkenone and Foraminifera Proxies Off NW Africa

    NASA Astrophysics Data System (ADS)

    Henderiks, J.; Bollmann, J.

    In Holocene deep-sea sediments, the relative abundance of different morphotypes within the coccolithophore genus Gephyrocapsa is closely correlated with sea sur- face temperature (Bollmann, 1997). Based on this relationship, a regional temperature transfer function was established using a set of 35 Holocene sediments from the NE Atlantic, covering a temperature range from 14C to 24C. Using this approach, ab- solute annual mean sea surface temperatures for a given location can be calculated from the relative abundance of two Gephyrocapsa morphotypes, Gephyrocapsa Cold and Gephyrocapsa Equatorial, with a standard deviation of +/-1.06C. A global regres- sion model (N=110) was applied as well, which calculates absolute mean sea surface temperatures from the relative abundance of three Gephyrocapsa morphotypes, with a standard deviation of +/-1.78C. Using both calibration models, we have estimated sea surface temperatures during the Last Glacial Maximum in a dispersed set of eigh- teen well-dated gravity cores off NW Africa (16-35N; 20-8W). The regional model revealed that annual mean temperatures during the LGM were 4 to 6C colder than today in the Canary Islands region, with lowest temperatures (14-15.5C) off-shore Morocco and south of the volcanic islands, likely due to intensified upwelling related to stronger trade winds. These values are consistent with estimates from the CLIMAP Project (1981) and other paleotemperature reconstructions for the same region. In con- trast, offshore Cape Blanc, our temperature estimates for the LGM are significantly warmer (Ttoday -LGM <4C) than proposed by CLIMAP (Ttoday -LGM 6-10C). Nevertheless, our results support temperature reconstructions based on alkenones that also indicate rather small temperature changes (Ttoday -LGM <3C) in this area (e.g. Zhao et al., 2000). Glacial sea surface temperature estimates derived from the global calibration are on average 1C warmer than those derived from the regional model. However, the

  5. Alkenone paleothermometry in the North Atlantic: A review and synthesis of surface sediment data and calibrations

    NASA Astrophysics Data System (ADS)

    Filippova, A.; Kienast, M.; Frank, M.; Schneider, R. R.

    2016-04-01

    Despite a clear correlation of alkenone unsaturation and sea surface temperatures (SST) throughout most parts of the ocean, scatter of the regression for various calibration equations has been shown to increase significantly at low SSTs. In this study, we combine previously published (n = 101) and new (n = 51) surface sediment data from the northern North Atlantic to constrain uncertainties of alkenone paleothermometry at low SSTs and to discuss possible sources of the increased scatter in the regression. The correlation between alkenone unsaturation and SSTs is strongest, in particular at the cold end (SSTs < 10°C), when the tetra-unsaturated alkenones (C37:4) are included in the unsaturation index (expressed as U37K) and regressed against spring-summer temperature. Surface ocean salinity and sea ice cover are not correlated with U37K per se. However, samples located in regions of permanent winter sea ice cover exhibit a significant warm bias. Deviation from the linear regression is posited to be related to a number of additional non-exclusive factors, such as advection of allochthonous material, local temperature stratification, and uncertainty in the absolute age of surface sediment samples assumed to be equivalent to modern conditions. We conclude that alkenone unsaturation allows accurate reconstruction of SST records from many regions of the North Atlantic if the factors confounding alkenone paleothermometry detailed here can be excluded.

  6. Understanding Abrupt, Natural Climate Variability Post-Industrial Revolution from the Subtropical Eastern Pacific: A Novel High Resolution Alkenone-derived Sea Surface Temperature Record

    NASA Astrophysics Data System (ADS)

    Kelly, C. S.; O'Mara, N. A.; Herbert, T.; Abella-Gutiérrez, J. L.; Herguera, J. C.

    2015-12-01

    Despite the ocean's importance in global biogeochemical feedbacks and heat storage, there is still a paucity of decadally-resolved sea surface temperature (SST) records to complement lacustrine and dendrological records of recent paleoclimate. Natural climate variability on multidecadal timescales is dominated by internal ocean circulation dynamics and feedbacks, and it is therefore imperative to employ marine proxies to reconstruct high resolution climate change. The timescales of this ocean-induced natural climate variability can be broken down into a few characteristic climate modes. Pressing questions about these modes include their stationarity in frequency and amplitude over time, in addition to the hypothesis that anthropogenic climate change has altered their behavior in comparison to natural variability. To pursue these questions, we must discern and analyze suitable climate archives in regions where modes of interest dominate modern climate variability. The region of Baja California, Mexico exhibits exceptional teleconnection to the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). Local, dramatic effects of ENSO and PDO on the marine biology and economy underline the importance of regional paleoclimate records from the Baja peninsula. Here, we present a high-resolution alkenone-derived SST reconstruction from the Industrial Revolution through the year 2000 by analysis of laminated box and Kasten sediment cores at Site PCM 00-78 (25.18°N, 112.66°W) in the subtropical eastern Pacific at a depth of 540 meters. Our SST record corresponds with NOAA extended reconstructed sea surface temperature, providing a robust basis for organic geochemical marine climatic reconstructions on timescales usually accessible only through speleothems, coral density bands, tree rings, and the like. Accordingly, based on this comparison to the historical data we expect our SST record may provide a more robust record of inter and multidecadal

  7. Fossil DNA Stratigraphy revealed Multiple Sources of Alkenones in the Holocene Black Sea at the Strain Level: Implications for UK37 Paleothermometry

    NASA Astrophysics Data System (ADS)

    Coolen, M. J.; Saenz, J. P.; Trowbridge, N.; Eglinton, T.

    2007-12-01

    The fossil distribution of long-chain alkenones is now a widely accepted tool to reconstruct past sea surface temperatures (SST) (i.e. UK37-index). In most studies, the UK37 index is calibrated for the main source of alkenones, the coccolithophorid haptophyte Emiliania huxleyi. Besides temperature, additional factors such as salinity, growth conditions, or different or multiple biological sources seem to influence the level of unsaturation of alkenones and the reliability of the UK37-inferred SST. The Black Sea is an interesting setting to study such factors since unreliable SST were reconstructed from the Holocene sapropel with high concentrations of an unusual "Black Sea" alkenone (C36:2 ethyl ketone) whereas calcium-bearing microfossils (coccoliths) of haptophytes are lacking. To identify Holocene sources for alkenones in the Black Sea at the unprecedented strain-level and to refine paleoenvironmental conditions, we searched for multiple fossil genetic signatures of haptophytes. This revealed that the slow increase in salinity as a result of post-glacial introduction of Mediterranean waters in the paleo lacustrine Black Sea, caused a succession between alkenone-biosynthesizing haptophytes from Isochrysis spp. (which do not produce coccoliths), to a mixture of Isochrysis and E huxleyi strains, then only E. huxleyi strains, and when the salinity reached a threshold of 18 per mille at 3000 years BP, the fossilized calcium-bearing E. huxleyi strain was introduced. At least 11 E. huxleyi strains were identified and the first non-fossilizing strains already colonized the Black Sea 4000 years before the fossilized calcium-bearing strain appeared. Most E. huxleyi strains were likely sources of C36:2 eK but the presence of one fossil "phylotype" coincided with the highest levels of this unusual alkenone ( more than 80 percent of the total alkenone content) and unreliable past SST (varying between 5 and 30 degrees C; 7500-5500 years BP). C36:2 eK was not biosynthesized by

  8. How Consistent are Sea Surface Temperature Estimates from Different Proxies? An Assessment of the Alkenone, Mg/Ca, and Faunal Paleothermometers Using Records from the Plio-Pleistocene

    NASA Astrophysics Data System (ADS)

    Lawrence, K. T.; Peterson, L.; deMenocal, P. B.; Bochner, L.; Gorbey, D. B.

    2014-12-01

    A variety of different paleothermometers have been used to estimate past sea surface temperature (SST). However, a limited number of studies have explored the consistency of the temperature estimates produced by these proxies or assessed the cross proxy reproducibility of the major results gleaned from these records. Here, incorporating novel and previously published records from a variety of different sites (ODP Site 662 in the Eastern Equatorial Atlantic, DSDP Site 607 and Site 609 in the North Atlantic, and ODP Site 1125 in the Southwest Pacific), we assess the consistency of the long-term trends and orbital signatures of Uk'37 SST records, relative to faunal and Mg/Ca estimates from the same sites. Exploring the similarity of companion SST datasets generated for different time windows within the Plio-Pleistocene at several different sites, we find that while there are structural differences between records, they produce very similar long-term trends and produce absolute temperature estimates that are generally within error of each other. Furthermore, companion records successfully capture the same dominant milankovtich period and produce phase estimates relative to benthic oxygen isotope estimates that are within error of each other. While there are some differences in the strength, temporal persistence, and presence/absence of the non-dominant milankovitch periodicies and some intervals in which one proxy record is coherent with δ18O while another is not, our results suggest that the primary results gleaned from SST proxy records remain intact regardless of which SST proxy is used.

  9. Alkenone Paleotemperature Determinations

    NASA Astrophysics Data System (ADS)

    Herbert, T. D.

    2003-12-01

    The organic biomarker proxy for past sea surface temperatures ("U37k") came to paleoceanography from an unexpected direction. Nearly all paleoceanographic tools rely on some aspect of the fossilized hard parts of marine organisms. Thus, assemblages of calcareous microplankton such as foraminifera and coccoliths, or of siliceous plankton such as radiolaria and diatoms, provided the basis for the CLIMAP reconstruction of the Ice Age ocean (CLIMAP, 1976, 1981). Additionally, a host of chemical methods relies on the same hard parts to furnish isotopic and trace element signatures, and generally requires that skeletal material be well preserved. The alkenone method differs in several important ways. Individual molecules, extracted and separated from a matrix of hundreds to thousands of other organic compounds, are the targets. In most cases, the remnant alkenones and alkenoates that are the subject of this review constitute no more, and often considerably less, than a few percent of their initial flux that left the surface layer of the ocean and fell toward the sediments. Good preservation is thus not a major issue for use of the proxy. In addition, while many geochemical techniques assume that skeletal material is a passive recorder of isotopic and trace element composition of seawater, and that incorporation of paleo-environmental signals follows thermodynamic laws that can be modeled using nonbiogenic phases in the laboratory, the alkenone method assumes that the ratios of biomarkers measured were actively regulated by the producing organisms in life according to the temperature of the water in which they grew.Alkenone paleothermometry promises a direct estimate of near-surface ocean temperatures. Alkenones and the related alkenoates come exclusively from a few species of haptophyte algae. These organisms require sunlight, and they generally prefer the upper photic zone. The environmental information contained in their molecular fossils therefore is quite specific

  10. New alkenones and derivatives in haptophytes

    NASA Astrophysics Data System (ADS)

    Rontani, J.-F.; Volkman, J. K.

    2003-04-01

    The alkenones comprise an unusual class of long-chain unsaturated methyl and ethyl ketones that are synthesized by a limited number of haptophyte microalgae. The relative abundance of the two main C37:2 and C37:3 alkenones expressed as the index [C37:2]/([C37:2] + [C37:3]) is now widely used for reconstructing sea surface paleotemperatures. A new technique involving NaBH4 reduction of alkenones to the corresponding alkenols and subsequent silylation was recently proposed for the characterisation and quantification of alkenones in natural samples (1). This reduction-silylation technique has proven to be very useful for the characterisation of previously unreported alkenones in microalgae, sediments and seawater. A re-examination of extracts of several haptophytes after this treatment allowed us to detect small amounts of C35-C38 monounsaturated alkenones. We could show that the double bonds of these compounds are present at w18 position instead of the expected w15 position. We have found large amounts of alkenols in extracts of some non-reduced sediments from Camargue (France); these compounds may result from a natural contribution of haptophytes or a non-selective bacterial reduction of alkenones under anoxic conditions. The possibility of a natural contribution of alkenols from haptophytes was tested and we were able to detect traces of alkenols in non-reduced extracts of Emiliania huxleyi, Gephyrocapsa oceanica and Isochrysis galbana. We examined also a benthic haptophyte Chrysotila lamellosa. The amounts of alkenols appeared to increase significantly during the senescence of C. lamellosa to reach 7% of the corresponding alkenones. In this species, we have also found non-negligible amounts of alkendiones and epoxyalkenones. LiAlD4 reduction of these compounds allowed us to characterise the positions of their additional keto and epoxy groups. Bacterial incubations under denitrifying conditions were also carried out in order to test the possibility of a bacterial

  11. Temperature calibration and phylogenetically distinct distributions for freshwater alkenones: Evidence from northern Alaskan lakes

    NASA Astrophysics Data System (ADS)

    Longo, William M.; Theroux, Susanna; Giblin, Anne E.; Zheng, Yinsui; Dillon, James T.; Huang, Yongsong

    2016-05-01

    Alkenones are a class of unsaturated long-chain ketone biomarkers that have been used to reconstruct sea surface temperature and, more recently, continental temperature, by way of alkenone unsaturation indices (e.g. U37K and U37K‧). Alkenones are frequently found in brackish and saline lakes, however species effects confound temperature reconstructions when multiple alkenone-producing species with different temperature responses are present. Interestingly, available genetic data indicate that numerous freshwater lakes host a distinct phylotype of alkenone-producing haptophyte algae (the Group I or Greenland phylotype), providing evidence that species effects may be diminished in freshwater lakes. These findings encourage further investigation of alkenone paleotemperature proxies in freshwater systems. Here, we investigated lakes from northern Alaska (n = 35) and show that alkenones commonly occurred in freshwater lakes, where they featured distinct distributions, characterized by dominant C37:4 alkenones and a series of tri-unsaturated alkenone isomers. The distributions were characteristic of Group I-type alkenone distributions previously identified in Greenland and North America. Our analysis of suspended particulate matter from Toolik Lake (68° 38‧N, 149° 36‧W) yielded the first in situ freshwater U37K calibration (U37K = 0.021 * T - 0.68; r2 = 0.85; n = 52; RMSE = ±1.37 °C). We explored the environmental significance of the tri-unsaturated isomers using our northern Alaskan lakes dataset in conjunction with new data from haptophyte cultures and Canadian surface sediments. Our results show that these temperature-sensitive isomers are biomarkers for the Group I phylotype and indicators of multiple-species effects. Together, these findings highlight freshwater lakes as valuable targets for continental alkenone-based paleotemperature reconstructions and demonstrate the significance of the recently discovered tri-unsaturated isomers.

  12. 18S rDNA analysis of alkenone-producing haptophyte(s) preserved in surface sediments of Lake Toyoni, Japan

    NASA Astrophysics Data System (ADS)

    McColl, J. L.; Couto, J.; Bendle, J. A.; Henderson, A. C.; Seki, O.; Phoenix, V. R.; Toney, J. L.

    2013-12-01

    Alkenones (long chain ketones) are readily preserved in sedimentary archives and have the potential to provide quantitative reconstructions of past water temperature. Alkenones are produced by a limited number of haptophyte algae in the marine and also some lacustrine systems. However, lakes are heterogeneous: an individual lake will have a unique combination of ecological conditions, haptophyte species and seasonal alkenone production that contributes to the sedimentary record. Haptophyte algae species have different sensitivities to temperature; therefore identifying the alkenone producer(s) prior to down-core temperature reconstructions is critical before selecting the most appropriate temperature calibration. We present a study from Lake Toyoni, a freshwater lake in Hokkaido, Japan that has alkenones preserved in surface sediments. The aim of this study is to identify the alkenone producer(s) within the lake using 18S rDNA analyses. Preserved rDNA of planktonic phototrophic algae was extracted from surface sediments of Lake Toyoni and phylogenetic analyses of the rDNA sequences suggest alkenones are produced by a single haptophyte within the class Prymnesiophyceae (order Isochrysidales). The Lake Toyoni alkenone-producer shares a distinct phylotype with a haptophyte reported from water filter samples collected in Lake BrayaSø, Greenland (D'Andrea et al., 2006). Similarity between the 18S rDNA sequences from Lake Toyoni and Lake BrayaSø provides a basis for applying (and updating) the Greenland lake temperature calibration. Applying this temperature calibration (T°C = 40.8 [UK37] + 31.8, R2=0.96; n=34) to the surface sediment alkenone unsaturation index from Lake Toyoni gives an estimated lake surface temperature (LST) of 8°C. This is in line with observed LST at Lake Toyoni, which ranges between 7 - 22°C (Apr 2011 to Nov 2011). The occurrence and identification of a single alkenone producer in Lake Toyoni means problems posed by a mixture of haptophytes in

  13. Salinity control on long-chain alkenone distributions in lake surface waters and sediments of the northern Qinghai-Tibetan Plateau, China

    NASA Astrophysics Data System (ADS)

    Liu, Weiguo; Liu, Zhonghui; Wang, Huanye; He, Yuxin; Wang, Zheng; Xu, Liming

    2011-04-01

    Long-chain alkenones in lacustrine settings are potentially excellent biomarkers for the reconstruction of past terrestrial environmental conditions, and have been found in many different types of lakes around the globe. A wider range of factors influence the occurrence and distribution of alkenones in lake sediments and waters when compared to marine systems. Lake environmental conditions, such as temperature (in particular) and salinity, are among the key factors controlling alkenone distributions in lacustrine settings. Here we investigated alkenone distribution patterns in lakes of the northern Qinghai-Tibetan Plateau, China, and their possible relationship with environmental conditions, by analyzing paired samples of suspended particulate matter in surface waters and surface sediments. Salinity of investigated lake waters ranges from almost 0 to ˜100 g/L, while temperature variation among the lakes is minimal, effectively eliminating temperature effects on the alkenone distribution patterns observed here. We show that (1) alkenone concentrations vary substantially between the lakes, yet controlling mechanisms remain elusive; (2) C 37/C 38 ratios are substantially lower in the lakes of the Qaidam Basin than in the Lake Qinghai region, probably indicating different alkenone producers in the two regions; and (3) large variations in %C 37:4 (the percentage of the C 37:4 alkenone), determined from both surface waters and sediments, are negatively correlated with salinity. We suggest that the %C 37:4 index could be used as a salinity indicator at least on a regional scale, with careful considerations of other potentially complicating factors. However, potential reasons for why salinity could significantly affect %C 37:4 values need further investigation.

  14. Relating Phylogeny to Alkenone Distributions in Lacustrine Alkenone-Producing Haptophytes: Implications for Continental Paleotemperature Reconstructions

    NASA Astrophysics Data System (ADS)

    Theroux, S.; D'Andrea, W. J.; Toney, J. L.; Zettler, L. A.; Huang, Y.

    2008-12-01

    The alkenone unsaturation index (Uk'37) is a widely used surface water paleotemperature proxy in marine settings, but has seen limited use in lacustrine environments. On-going discovery of alkenone- containing lake sediments worldwide expand our ability to reconstruct continental paleotemperatures. However, disparate alkenone profiles among these lakes suggest a diversity of alkenone-producing organisms. The utility of the paleotemperature proxy is constrained by the accurate calibration of the Uk'37 against temperature for individual lakes. In this study, we report the findings from an 18S rRNA gene-based phylogenetic survey of globally distributed lakes containing alkenone-producing haptophyte algae to infer which haptophyte lineages likely possess common alkenone production pathways. Our phylogenetic analyses reveal that monophyletic groups of haptophytes possess similar lipid profiles. This correlation indicates the potential for applying a minimal number of calibrations to a multitude of diverse geographic settings. Furthermore, the expanded dataset of alkenone-containing lake sediments and robust phylogenetic analyses reflect the evolution of alkenone-producing haptophytes, and provide insights into the last common ancestor that was capable of alkenone production in the Cretaceous. The physiology, behavior, and culture conditions of a newly-isolated alkenone-producing haptophyte from polar waters possessing anomalous alkenone-concentrations, will also be discussed.

  15. Post-depositional stability of long-chain alkenones under contrasting redox conditions

    NASA Astrophysics Data System (ADS)

    Prahl, F. G.; de Lange, G. J.; Lyle, M.; Sparrow, M. A.

    1989-10-01

    PRYMNESIOPHYTE algae, which include the coccolithophorid species Emiliania huxleyi1, are the recognized biological source of a series of long-chain (C37, c38, 39, unsaturated methyl and ethyl ketones2 widely observed in marine sediments3. Studies of E. huxleyi in culture have demonstrated that these biomarkers are attractive geochemical tools for palaeoceanographic study. No-tably, unsaturation patterns within the alkenone series change regularly with growth temperature 3-5 and the total alkenone abundance in the living plant cell is relatively constant, accounting for 5-10% of the total cellular organic carbon5. If these com-pounds are relatively well-preserved in sediments, profiles of alkenone unsaturation patterns and total alkenone concentration with depth in dated deep-sea cores6-8 provide a temporal record of sea surface temperatures and the productivity of an important group of marine phytoplankton3-5. Here we analyse the long-chain alkenone composition of sediment samples from above and below an oxidation front in an ungraded turbidite layer9 deposited 140 +/-12 kyr BP in the Madeira Abyssal Plain10, to evaluate the post-depositional stability of these biomarkers under contrasting redox conditions. The results demonstrate that >85% of the total amount of these compounds is degraded over ~8 kyr as a consequence of diffusion-controlled oxidation10. Remarkably, such extensive degradative loss has little effect on the unsaturation pattern of the residual biomarker series. Thus, we find that long-chain alkenones provide reliable indicators of sea surface temperature in the ocean. The total abundance of these biomarkers in sediments, however, is controlled not only by prymnesiophyte productivity, but also by their degree of exposure to oxidative degradation in the sedimentary process.

  16. New culturing studies of various haptophyte algae: The role of phylogeny on the alkenone paleothermometer

    NASA Astrophysics Data System (ADS)

    Walker Karega, I. I.; D'Andrea, W. J.; Juhl, A. R.

    2015-12-01

    Alkenone paleothermometry (via the Uk37and UK'37 indices) is widely used to reconstruct sea surface temperature and, more recently, lake water temperature. Genetic analyses indicate that there is a diversity of different alkenone-producing lacustrine haptophytes, and differences among UK37-temperature calibrations suggest that unique calibrations might be required to quantify past temperature variation from individual lakes. The only term needed to quantify UK37-inferred temperature relative to a reference period (e.g., modern temperature, or 20th Century mean temperature) is the slope of the calibration regression: UK37-temperature sensitivity (i.e., the change in UK37 per °C temperature change). Here, we present new data developed by culturing four different species of alkenone-producing haptophyte algae across a range of temperatures (6-30 °C) and light levels (20-200 mE). The simultaneous culture of four distinct species allows direct comparison of the absolute quantities of alkenones and alkenoates, as well as other lipids, produced by different species of haptophytes under identical environmental conditions. Our results indicate that algal growth rate, when controlled by light intensity, has no impact on values. As expected, we find that growth temperature controls both the degree of alkenone unsaturation and the relative production of alkenones vs. alkenoates in all four species. Importantly, comparison of the four UK37-temperature calibrations resulting from our experiments with preexisting calibrations supports the hypothesis that UK37-temperature sensitivity is controlled by phylogeny. Therefore, even in the absence of a site-specific calibration, this term can be used to quantify past temperature variation from lake sediments if the genetic identity of the lake's alkenone-producer is known.

  17. Large effect of irradiance on hydrogen isotope fractionation of alkenones in Emiliania huxleyi

    NASA Astrophysics Data System (ADS)

    van der Meer, Marcel T. J.; Benthien, Albert; French, Katherine L.; Epping, Eric; Zondervan, Ingrid; Reichart, Gert-Jan; Bijma, Jelle; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2015-07-01

    The hydrogen isotopic (δD) composition of long-chain alkenones produced by certain haptophyte algae has been suggested as a potential proxy for reconstructing paleo sea surface salinity. However, environmental parameters other than salinity may also affect the δD of alkenones. We investigated the impact of the level of irradiance on hydrogen isotopic fractionation of alkenones versus growth water by cultivating two strains of the cosmopolitan haptophyte Emiliania huxleyi at different light intensities. The hydrogen isotope fractionation decreased by approximately 40‰ when irradiance was increased from 15 to 200 μmol photons m-2 s-1 above which it was relatively constant. The response is likely a direct effect of photosystem I and II activity as the relationship of the fractionation factor α versus light intensity can be described by an Eilers-Peeters photosynthesis model. This irradiance effect is in agreement with published δD data of alkenones derived from suspended particulate matter collected from different depths in the photic zone of the Gulf of California and the eastern tropical North Pacific. However, haptophyte algae tend to bloom at relatively high light intensities (>500 μmol photons m-2 s-1) occurring at the sea surface, at which hydrogen isotope fractionation is relatively constant and not affected by changes in light intensity. Alkenones accumulating in the sediment are likely mostly derived from these surface water haptophyte blooms, when the largest amount of biomass is produced. Therefore, the observed irradiance effect is unlikely to affect the applicability of the hydrogen isotopic composition of sedimentary long chain alkenones as a proxy for paleosalinity.

  18. Possible Climatic Signal Recorded by Alkenone Distributions in Sediments from Freshwater and Saline Lakes on the Skarvsnes and Skallen Areas, Antarctica

    NASA Astrophysics Data System (ADS)

    Sawada, K.; Takeda, M.; Takano, Y.

    2014-12-01

    The distribution of long-chain (C37 - C39) alkenones in marine sediment has been well documented to record paleo-sea surface temperatures. The alkenones were also found in sediments of terrestrial saline lakes, and recently the calibrations of alkenone unsaturation indices - temperature have been established in continental areas. Furthermore, these biomarkers have been identified in lacustrine sediments on high-latitudinal terrestrial areas such as Greenland and Antarctica. In the present study, the alkenones were identified in the lacustrine sediment cores in freshwater (Lake Naga-ike) and saline lakes (Lake Suribati and Lake Funazoko) on the Skarvsnes, and a saline lake (Lake Skallen Oh-ike) on the Skallen, Antarctica. Here, we report that the alkenone distribution in the Antarctic lakes was examined as paleotemperature proxy. C37-C38 Tetra- and tri-unsaturated alkenones and C37 tetra- and tri-unsaturated alkenoates are identified in all sediment samples. The C37 di-unsaturated (C37:2) alkenones can be identified in sediments of surface layers (0-15 cm) of Lake Naga-ike and layers of 160-190 cm depth, in which age is ca. 3000 years BP by 14C dating, in Lake Skallen Ohike, and alkenone unsaturation index (UK37) is analyzed from these sediments. By using a calibration obtained from a culture strain Chrysotila lamellosa as reported by Nakamura et al. (2014), paleotemperatures are calculated to be 9.2-15ºC in surface sediments of Lake Naga-ike and 6.8-8.6ºC in Lake Skallen Oh-ike, respectively. The estimated temperatures are concordant with summer temperature of lake waters observed in Lake Naga-ike. Also, the highest concentrations of the alkenones and alkenoates are observed in deeper (older) sediment layers from Lake Naga-ikes, which has not been connected the ocean and intruded sea water. This implies that the alkenones are originated from indigenous biological organism(s) in Antarctic lake water. The class distributions (unsaturation ratios) of alkenones

  19. Factors influencing 14C concentrations of algal and archaeal lipids and their associated sea surface temperature proxies in the Black Sea

    NASA Astrophysics Data System (ADS)

    Kusch, Stephanie; Rethemeyer, Janet; Hopmans, Ellen C.; Wacker, Lukas; Mollenhauer, Gesine

    2016-09-01

    Understanding the preservation and deposition history of organic molecules is crucial for the understanding of paleoenvironmental information contained in their abundance ratios such as Uk‧37 and TEX86 used as proxies for sea surface temperature (SST). Based on their relatively high refractivity, alkenones and glycerol dialkyl glycerol tetraethers (GDGTs) can survive postdepositional processes like lateral transport, potentially causing inferred SSTs to be misleading. Likewise, selective preservation of alkenones and GDGTs may cause biases of the SST proxies themselves and can lead to decoupling of both proxy records. Here we report compound-specific radiocarbon data of marine biomarkers including alkenones, GDGTs, and low molecular weight (LMW) n-fatty acids from Black Sea sediments deposited under different redox regimes to evaluate the potentially differential preservation of both biomarker classes and its effect on the SST indices Uk‧37 and TEX86. The decadal Δ14C values of alkenones, GDGTs, and LMW n-fatty acids indicate similar preservation under oxic, suboxic, and anoxic redox regimes and no contribution of pre-aged compounds, e.g., by lateral supply. Moreover, similar 14C concentrations of crenarchaeol, alkenones, and LMW n-fatty acids imply that the thaumarchaeotal GDGTs preserved in these sediments are produced in the euphotic zone rather than in subsurface/thermocline waters. However, we observe biomarker-based SSTs that strongly deviate (ΔSST up to 8.4 °C) from in situ measured mean annual SSTs in the Black Sea. This is not due to redox-dependent differential biomarker preservation as implied by their Δ14C values and spatial SST pattern. Since contributions from different sources can largely be excluded, the deviation of the Uk‧37 and TEX86 proxy-derived SSTs from in situ SSTs requires further study of phylogenetic and other yet unknown environmental controls on alkenone and GDGT lipid distributions in the Black Sea.

  20. Alkenone temperature and salinity: An evaluation of long chain C37 alkenone in Lake Qinghai, China

    NASA Astrophysics Data System (ADS)

    Liu, W.; Liu, Z.; Fu, M.; An, Z.

    2007-12-01

    In recently years, the alkenone unsaturation index (Uk'37=C37:.2/(C37:2+ C37:3)) has been used to reconstructed paleo-temperature for lacustrine sediments. However, few studies have addressed whether the relative abundance of the C37:4 alkenone to the total C37 production (C37:4 percent) can reflect surface salinity changes in lake systems. Here we present the distribution of C37 long chain alkenone of modern lake sediments in Qinghai Lake, Qing-Tibet Plateau, to evaluate significance of abundance change of long chain C37 alkenone as an indicator of lake paleo-enviromental evolution. A group of surface sediments from different locations in the lake have been analyzed in this study. The results of long chain C37 alkenone from 28 surface sediments analyses shown relative abundance of C37:4 alkenone to total C37 production (C37:4 percent) change from 14.5 to 48.6 percent and the abundance of C37:4 alkenone is increasing with decreasing salinity of lake water. For the salinity lake in land, we suggested the relative abundance of C37:4 alkenone in lake sediments may be a indicator of paleo-silinity; We have also found that Uk'37 values are weakly correlated with salinity and C37:4 percent changes, implying that potential minor contributions of temperature and salinity effects to C37:4 percent and Uk'37 respectively cannot be excluded in this study. However, since these contributions are weak, we suggest that the C37:4 percent proxy can be used to reconstruct paleo-salinity changes at a regional scale, especially in lake systems, while Uk'37 remains as a powerful tool for reconstructions of paleo-temperature changes in the lake systems.

  1. Hydrogen isotopes in individual alkenones from the Chesapeake Bay estuary

    NASA Astrophysics Data System (ADS)

    Schwab, Valérie F.; Sachs, Julian P.

    2011-12-01

    Hydrogen isotope ratios of individual alkenones from haptophyte algae were measured in suspended particles and surface sediment from the Chesapeake Bay (CB) estuary, eastern USA, in order to determine their relationship to water δD values and salinity. δD values of four alkenones (MeC 37:2, MeC 37:3, EtC 38:2, EtC 38:3) from particles and sediments were between -165‰ and -221‰ and increased linearly ( R2 = 0.7-0.9) with water δD values from the head to the mouth of the Bay. Individual alkenones were depleted in deuterium by 156-188‰ relative to water. The MeC 37 alkenones were consistently enriched by ˜12‰ relative to the EtC 38 alkenones, and the di-unsaturated alkenones of both varieties were consistently enriched by ˜20‰ relative to the tri-unsaturated alkenones. All of the increase in alkenone δD values could be accounted for by the water δD increase. Consequently, no net change in alkenone-water D/ H fractionation occurred as a result of the salinity increase from 10 to 29. This observation is at odds with results from culture studies with alkenone-producing marine coccolithophorids, and from two field studies, one with a dinoflagellate sterol in the CB, and one with a wide variety of lipids in saline ponds on Christmas Island, that indicate a decline in D/ H fractionation with increasing salinity. Why D/ H fractionation in alkenones in the CB showed no dependence on salinity, while D/ H fractionation in CB dinsoterol decreased by 1‰ per unit increase in salinity remains to be determined. Two hypotheses we consider to be valid are that (i) the assemblage of alkenone-producing haptophytes changes along the Bay and each species has a different sensitivity to salinity, such that no apparent trend in αalkenone-water occurs along the salinity gradient, and (ii) greater osmoregulation capacity in coastal haptophytes may result in a diminished sensitivity of alkenone-water D/ H fractionation to salinity changes.

  2. Towards an organic palaeosalinity proxy: the effect of salinity, growth rate and growth phase on the hydrogen isotopic composition of alkenones produced by haptophyte algae

    NASA Astrophysics Data System (ADS)

    Chivall, David; M'Boule, Daniela; Schouten, Stefan; Sinninghe Damsté, Jaap S.; van der Meer, Marcel T. J.

    2013-04-01

    Palaeosalinity is one of the most important oceanographic parameters which currently cannot be quantified with reasonable accuracy from sedimentary records. Schouten et al.1 established that the fractionation of hydrogen isotopes between growth water and alkenones produced by the haptophyte algae Emiliania huxleyi and Gephyrocapsa oceanica is salinity dependent. As such, the δD values of alkenones recovered from sediment cores can be used to reconstruct variations in palaeo- sea surface salinity.2 However, to accurately determine absolute palaeosalinity requires a better constraining of the relationship between this hydrogen fractionation, salinity and other parameters such as growth rate and growth phase. Here, we present results from our ongoing work to constrain the relationship between the fractionation factor αalkenone-water, salinity, growth rate and growth phase for the major alkenone-producing haptophytes. In batch cultures of different strains of the open-ocean haptophyte E. huxleyi sampled during the exponential growth phase, αC37alkenone-growthwater increases by between 0.0022 and 0.0033 per unit increase in salinity. A similar relationship is observed in batch cultures of the coastal haptophyte Isochrysis galbana, where α increases with each unit of salinity by 0.0019 - slightly less than for E. huxleyi. However, absolute αC37alkenone-growthwater values vary strongly between species suggesting that species composition has a strong impact on the δD value of alkenones. The fractionation factor for alkenones produced by batch cultures of I. galbana is affected by growth phase: the rate of change of αC37alkenone-growthwater with each unit of salinity decreases from 0.0019 in the exponential phase to 0.0010 during the stationary phase. We also show the effect of varying growth rate over the range 0.2-0.8 day-1 on the fractionation factor for alkenones produced by E. huxleyi grown in continuous culture. These data show that alkenone δD can be used to

  3. Does phylogeny control U37K -temperature sensitivity? Implications for lacustrine alkenone paleothermometry

    NASA Astrophysics Data System (ADS)

    D'Andrea, William J.; Theroux, Susanna; Bradley, Raymond S.; Huang, Xiaohui

    2016-02-01

    Alkenone paleothermometry (via the U37K and U37K‧ indices) has long been used to reconstruct sea surface temperature and has more recently been proven effective in lacustrine settings. Genetic analyses indicate that there is a diversity of different alkenone-producing lacustrine haptophytes, and differences among U37K -temperature calibrations suggest that unique calibrations might be required to quantify past temperature variation from individual lakes. The only term necessary to quantify U37K -inferred temperature relative to a reference period (e.g., modern temperature 20th Century mean) is the slope of the calibration regression, the U37K -temperature sensitivity (i.e., the change in U37K per °C temperature change). Here, we bring together all of the existing U37K -temperature calibrations in order to compare the variability among U37K -temperature sensitivities. We also report a new in situ U37K -temperature calibration along with environmental genomic analysis based on the 18S rRNA gene of an alkenone producing haptophyte from lake Vikvatnet in Norway. We propose and test the hypothesis that U37K -temperature sensitivity is controlled by phylogeny and that this term can be used to quantify past temperature variation from lake sediments if the genetic identity of the lake's alkenone-producer is known. Using the existing calibration data sets, we determine four phylotype-specific U37K -temperature sensitivities for use in cases where in situ calibration is unavailable but the phylogeny of the alkenone producers is known.

  4. DNA and lipid molecular stratigraphic records of haptophyte succession in the Black Sea during the Holocene

    NASA Astrophysics Data System (ADS)

    Coolen, Marco J. L.; Saenz, James P.; Giosan, Liviu; Trowbridge, Nan Y.; Dimitrov, Petko; Dimitrov, Dimitar; Eglinton, Timothy I.

    2009-07-01

    Previous studies suggest that the coccolithophorid haptophyte Emiliania huxleyi entered the Black Sea ~ 3400 yrs ago and since then a coccolith ooze defined as Unit I has developed. Unit I sediments contain long-chain alkenones derived from E. huxleyi whereas the alkenone distribution of the deeper coccolith-free sapropel (Unit II) is rather unusual. Alkenone-derived past sea surface temperature (SST) estimates suggest a large difference between Unit II and Unit I, which is likely a result of unusual biological precursors of the alkenones in Unit II. Here, we report a high-resolution stratigraphic analysis of ancient haptophyte DNA to establish the Holocene succession of haptophytes as sources of the alkenones in the Black Sea. Haptophytes related to brackish Isochrysis spp. were the initial sources of alkenones, and appeared immediately after the onset of sapropel deposition (~ 7550 yrs before present [a BP]). As salinity increased, Isochrysis-related haptophytes were slowly replaced by a complex suite of E. huxleyi strains as sources of alkenones. Our paleogenetic data showed that E. huxleyi colonized the Black Sea shortly after the onset of sapropel deposition, ~ 4000 yrs earlier than previously recognized based on their preserved coccoliths. E. huxleyi strains were the most likely source of the previously reported abundant and unusual C 36 di-unsaturated "Black Sea alkenone". Strong haptophyte species and strain-specific effects were observed on the level of unsaturation of alkenones which resulted in spurious alkenone-derived SST estimates before 5250 a BP. In contrast, from ~ 5250 a BP onwards a relatively stable haptophyte assemblage dominated by a different suite of E. huxleyi strains yielded robust alkenone-SST values and indicated a gradual cooling from 19 °C to ~ 15 °C at the top of the record (~ 450 a BP).

  5. Excluding the di-unsaturated alkenone in the UK37 index strengthens temperature correlation for the common lacustrine and brackish-water haptophytes

    NASA Astrophysics Data System (ADS)

    Zheng, Yinsui; Huang, Yongsong; Andersen, Robert A.; Amaral-Zettler, Linda A.

    2016-02-01

    Alkenone unsaturation indices, represented by either UK37 or UK‧37, are important tools for paleoclimate studies. The UK37 index is a reflection of the average number of double bonds from di-, tri-, tetra-unsaturated alkenones, but UK‧37 excludes the C37:4 in the calculation. Extensive studies indicate UK‧37 provides better regressions against in situ Sea Surface Temperatures (SST) than UK37 and is the most widely used SST proxy. However, recent studies have shown that including C37:4 alkenones for lacustrine or brackish water haptophytes such as Ruttnera (Chrysotila) lamellosa and Isochrysis galbana improves temperature correlations although there are still significant deviations at the extreme high and low temperatures. In this study, we use new culture-based calibration experiments alongside published culture data and in situ water column or surface sediment data, to demonstrate that a further improved temperature calibration for alkenones is, in fact, achieved when the di-unsaturated alkenone is excluded from the computation of the unsaturation index. We propose new indices, termed UK″ [UK″37 = C37:3/(C37:3 + C37:4) or UK″38 = C38:3/(C38:3 + C38:4)], for lacustrine, brackish and estuarine waters. Our observation suggests that di-unsaturated alkenones play a less important role than tri- and tetra-unsaturated alkenones in regulating cell functions to temperature variations in lacustrine and brackish waters. We suggest using UK″ indices for paleotemperature reconstructions in the lacustrine and estuarine settings.

  6. Concentrations and abundance ratios of long-chain alkenones and glycerol dialkyl glycerol tetraethers in sinking particles south of Java

    NASA Astrophysics Data System (ADS)

    Chen, Wenwen; Mohtadi, Mahyar; Schefuß, Enno; Mollenhauer, Gesine

    2016-06-01

    In this study, we obtained concentrations and abundance ratios of long-chain alkenones and glycerol dialkyl glycerol tetraethers (GDGTs) in a one-year time-series of sinking particles collected with a sediment trap moored from December 2001 to November 2002 at 2200 m water depth south of Java in the eastern Indian Ocean. We investigate the seasonality of alkenone and GDGT fluxes as well as the potential habitat depth of the Thaumarchaeota producing the GDGTs entrained in sinking particles. The alkenone flux shows a pronounced seasonality and ranges from 1 μg m-2 d-1 to 35 μg m-2 d-1. The highest alkenone flux is observed in late September during the Southeast monsoon, coincident with high total organic carbon fluxes as well as high net primary productivity. Flux-weighted mean temperature for the high flux period using the alkenone-based sea-surface temperature (SST) index U37K‧ is 26.7 °C, which is similar to satellite-derived Southeast (SE) monsoon SST (26.4 °C). The GDGT flux displays a weaker seasonality than that of the alkenones. It is elevated during the SE monsoon period compared to the Northwest (NW) monsoon and intermonsoon periods (approximately 2.5 times), which is probably related to seasonal variation of the abundance of Thaumarchaeota, or to enhanced export of GDGTs by aggregation with sinking phytoplankton detritus. Flux-weighted mean temperature inferred from the GDGT-based TEX86H index is 26.2 °C, which is 1.8 °C lower than mean annual (ma) SST but similar to SE monsoon SST. As the time series of TEX86H temperature estimates, however, does not record a strong seasonal amplitude, we infer that TEX86H reflects ma upper thermocline temperature at approximately 50 m water depth.

  7. Reevaluation of mid-Pliocene North Atlantic sea surface temperatures

    USGS Publications Warehouse

    Robinson, Marci M.; Dowsett, Harry J.; Dwyer, Gary S.; Lawrence, Kira T.

    2008-01-01

    Multiproxy temperature estimation requires careful attention to biological, chemical, physical, temporal, and calibration differences of each proxy and paleothermometry method. We evaluated mid-Pliocene sea surface temperature (SST) estimates from multiple proxies at Deep Sea Drilling Project Holes 552A, 609B, 607, and 606, transecting the North Atlantic Drift. SST estimates derived from faunal assemblages, foraminifer Mg/Ca, and alkenone unsaturation indices showed strong agreement at Holes 552A, 607, and 606 once differences in calibration, depth, and seasonality were addressed. Abundant extinct species and/or an unrecognized productivity signal in the faunal assemblage at Hole 609B resulted in exaggerated faunal-based SST estimates but did not affect alkenone-derived or Mg/Ca–derived estimates. Multiproxy mid-Pliocene North Atlantic SST estimates corroborate previous studies documenting high-latitude mid-Pliocene warmth and refine previous faunal-based estimates affected by environmental factors other than temperature. Multiproxy investigations will aid SST estimation in high-latitude areas sensitive to climate change and currently underrepresented in SST reconstructions.

  8. Mid-Piacenzian sea surface temperature record from ODP Site 1115 in the western equatorial Pacific

    USGS Publications Warehouse

    Stoll, Danielle

    2010-01-01

    Planktic foraminifer assemblages and alkenone unsaturation ratios have been analyzed for the mid-Piacen-zian (3.3 to 2.9 Ma) section of Ocean Drilling Program (ODP) Site 1115B, located in the western equatorial Pacific off the coast of New Guinea. Cold and warm season sea surface temperature (SST) estimates were determined using a modern analog technique. ODP Site 1115 is located just south of the transition between the planktic foraminifer tropical and subtropical faunal provinces and approximates the southern boundary of the western equatorial Pacific (WEP) warm pool. Comparison of the faunal and alkenone SST estimates (presented here) with an existing nannofossil climate proxy shows similar trends. Results of this analysis show increased seasonal variability during the middle of the sampled section (3.22 to 3.10 Ma), suggesting a possible northward migration of both the subtropical faunal province and the southern boundary of the WEP warm pool.

  9. Glacial-to-Holocene evolution of sea surface temperature and surface circulation in the subarctic northwest Pacific and the Western Bering Sea

    NASA Astrophysics Data System (ADS)

    Meyer, Vera D.; Max, Lars; Hefter, Jens; Tiedemann, Ralf; Mollenhauer, Gesine

    2016-07-01

    It has been proposed that North Pacific sea surface temperature (SST) evolution was intimately linked to North Atlantic climate oscillations during the last glacial-interglacial transition. However, during the early deglaciation and the Last Glacial Maximum, the SST development in the subarctic northwest Pacific and the Bering Sea is poorly constrained as most existing deglacial SST records are based on alkenone paleothermometry, which is limited prior to 15 ka B.P. in the subarctic North Pacific realm. By applying the TEXL86 temperature proxy we obtain glacial-Holocene-SST records for the marginal northwest Pacific and the Western Bering Sea. Our TEXL86-based records and existing alkenone data suggest that during the past 15.5 ka, SSTs in the northwest Pacific and the Western Bering Sea closely followed millennial-scale climate fluctuations known from Greenland ice cores, indicating rapid atmospheric teleconnections with abrupt climate changes in the North Atlantic. Our SST reconstructions indicate that in the Western Bering Sea SSTs drop significantly during Heinrich Stadial 1 (HS1), similar to the known North Atlantic climate history. In contrast, progressively rising SST in the northwest Pacific is different to the North Atlantic climate development during HS1. Similarities between the northwest Pacific SST and climate records from the Gulf of Alaska point to a stronger influence of Alaskan Stream waters connecting the eastern and western basin of the North Pacific during this time. During the Holocene, dissimilar climate trends point to reduced influence of the Alaskan Stream in the northwest Pacific.

  10. Environmental and Climatic Control on the Occurrence and Abundance of Long Chain Alkenones in Lakes of the Interior United States

    NASA Astrophysics Data System (ADS)

    Toney, J. L.; Fritz, S.; Baker, P. A.; Grimm, E. C.; Nyren, P.; Theroux, S.; Huang, Y.

    2008-12-01

    Long chain alkenones are a class of temperature sensitive lipids with great potential for quantitative paleoclimatic reconstructions from continental locations. We have surveyed 57 lacustrine core-top sediments in the in the interior US for alkenones in order to constrain the environmental conditions that control the occurrence of alkenone-producing haptophytes in lakes and determine the possibility of using lacustrine alkenones to reconstruct temperature. Thirteen out of the 57 sites surveyed contain alkenones in surface sediments. Three of the 13 lakes contain abundant C37:4 alkenones as commonly found in lake sediments, whereas the rest of the lakes show a surprising absence of C37:4 alkenone. 18S Ribosomal DNA sequences amplified from the C37:4 containing lakes suggests the alkenone-producing haptophyte falls amongst the Isochrysis spp. and showcases a strong similarity to a haptophyte derived from Ace Lake, Antarctica, whereas the other lakes probably contain a different species. We also find cold, oligosaline conditions with high concentrations of sodium and sulfate promote high concentrations of alkenones. Salinity serves as a threshold control on the C37:4 alkenone such that C37:4 is only found in lakes with salinity above 2.74 g / L. Sites with the C37:4 alkenone plot along a previously published calibration. We also create a new alkenone temperature calibration using water column filters from Lake George spanning a temperature range of 8 to 24 degrees C. In addition, we obtain an alkenone- inferred temperature record from Lake George, ND for the instrumental period and a high-resolution (~20 year resolution) Holocene length record from Brush Lake, MT, in order to further assess the applicability of lacustrine alkenones for continental paleo-temperature reconstructions.

  11. Unusual ∆7,12,19 C35:3 Alkenone Produced by the Mutant Emiliania huxleyi strain CCMP2758 in Culture

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Huang, Y.; Zhang, Y.; Dillon, J. T.

    2015-12-01

    Alkenones with chain length ranging from C37 to C40 are highly specific biomarkers for certain haptophyte algae in ocean and lake sediments and have been widely used for paleoclimate studies. Short chain alkenones (e.g., C35 and C36) have been found in environmental and culture samples but the origin and structures of these compounds are not fully understood. The benchmark marine alkenone producer, Emiliania huxleyi CCMP2758 strain (the mutant of strain CCMP1742, NEPCC55a) was reported to make 35:2 alkenone when cultured at 15 °C (Prahl et al., 2006). Here we show, when this strain is cultured at lower temperatures (e.g., 4°C), CCMP2758 produces large amount of 35:3 alkenone with unusual double bond positions of ∆7,12,19. We determined the double bond positions of the C35:3 methyl ketonee based on GC-MS analysis of cyclobutylimine derivatives and dimethyl disulfide derivatives respectively, and provide the first temperature calibrations based on the unsaturation ratios of C35 alkenones. Previous studies have found 35:2 alkenone with three methylene interruption in the Black Sea sediment, but it is the first time that an alkenone with a mixed three and five methylene interruption is found. The discovery of short chain alkenones with unusual double bond positions may shed new light to alkenone biosynthesis.

  12. Time-series of water column alkenones and 18S rRNA confirm that Uk'37 is a viable SST proxy in Narragansett Bay, RI

    NASA Astrophysics Data System (ADS)

    Salacup, J.; Theroux, S.; Herbert, T.; Prell, W. L.

    2011-12-01

    Alkenones, produced in the sunlit mixed layer by specific Haptophyte algae, are a well-established and widely-applied proxy for sea surface temperature (SST) in the world's open-oceans. However, the proxy's utility in estuarine environments remains largely untested. A reliable SST proxy is needed to identify the estuary's sensitivity and response to past and present global change because SST can exert strong control on stratification and circulation patterns, and thus oxygenation and ecosystem health, in these shallow basins. Knowing the estuaries response should help local managers and policy-makers plan mitigation and adaptation strategies. Additionally, the rapid deposition of both marine and terrestrial organic and inorganic material in estuarine systems makes them potential archives of high-resolution paleo-environmental information. A previous investigation of estuarine alkenones suggested that the Uk'37 proxy may be sensitive to the composition of the alkenone-producing Haptophyte population, which may be affected by local nutrient and fresh water fluxes. In particular, low-salinity coastal Haptophytes such as Isochrysis galbana may have a different relationship to SST than higher-salinity open-ocean Haptophytes and their presence may complicate interpretations of the Uk'37 proxy in estuaries. To better understand how the alkenone-based Uk'37 SST proxy is produced in estuarine systems, we present a two-year time-series (monthly-to-thrice-weekly resolution) of alkenone concentrations in particulate organic matter from Narragansett Bay. Alkenone concentrations are coupled with 18S ribosomal RNA (rRNA) measurements to identify the alkenone-producing population. Highest concentrations of alkenones are detected at different times in the upper and lower Bay such that the highest alkenone concentrations occur in the winter-spring (upper Bay) and summer/fall (lower Bay). This result is consistent with the established seasonal blooms and seasonal changes in nutrient

  13. Subpolar gyre and radiative forcings moderate sea surface temperatures of the Norwegian Sea during the mid-Piacenzian

    NASA Astrophysics Data System (ADS)

    Bachem, Paul; Risebrobakken, Bjørg; McClymont, Erin

    2016-04-01

    The mid-Piacenzian age (ca. 3.3-3.0 Ma) of the Pliocene epoch has been proposed as a possible reference for future warm climate states. We have developed a new set of orbital-resolution alkenone-based sea surface temperature (SST) and ice rafted debris (IRD) records from the Norwegian Sea. SSTs in the Norwegian Sea were 2-3°C warmer in the mid-Piacenzian compared to the Holocene average. There is notable orbital-scale SST variability with a range of 4°C. The most likely cause of the average long-term warmth is a higher atmospheric CO2 concentration. A correlation of SST variability with the presence of Greenland-sourced IRD suggests a common climate forcing acting across the Nordic Seas region. The orbital-scale variability was in part caused by interplay of obliquity and precession, as low SSTs coincide with times of low northern summer insolation. Changes of the SST gradient between the Norwegian Sea and North Atlantic sites suggest that the subpolar gyre was at least of comparable strength as during the Holocene. The North Atlantic Current (NAC) influence on the Norwegian Sea SSTs does not appear to have been stronger than during the Holocene.

  14. Alkenone molecular stratigraphy in an oceanic environment affected by glacial freshwater events

    NASA Astrophysics Data System (ADS)

    Jasper, John P.; Gagosian, Robert B.

    1989-12-01

    The sedimentary record of a ratio (UK37) of long chain (C37) unsaturated alkenones is a useful indicator of glacial-interglacial climatic change in the Late Quaternary northern Gulf of Mexico where a planktonic foraminiferal δ18O-CaCO3 record is complicated by meltwater and/or fluvial events (Williams and Kohl, 1986). Application of a laboratory temperature calibration of the UK37 ratio (Prahl and Wakeham, 1987) to a Pigmy Basin hydraulic piston core record (Deep Sea Drilling Project core 619) suggested that the minimum glacial surface mixed layer (SML) temperature was 8°±1°C colder than the Holocene high SML temperature of 25.6°±0.5°C. This predicted glacial-interglacial temperature difference was significantly larger than the differences predicted by either the foraminiferal δ18O or foraminiferal assemblage temperature methods (0.8°-2.0°C). This large difference may be caused by local Prymnesiophyte assemblage changes in response to climatically induced hydrographic changes. Interglacial periods may be dominated by pelagic Prymnesiophyte assemblages, while glacial periods may be dominated by neritic assemblages. A combined mechanism of both climatically varying Prymnesiophyte species assemblage and depth of alkenone biosynthesis may account for the large difference between the temperature methods.

  15. Sea surface temperature and salinity patterns in the northern North Atlantic and the Arctic during interglacial MIS 11c: Implications for oceanic circulation reconstruction

    NASA Astrophysics Data System (ADS)

    Kandiano, E.; van der Meer, M.; Schouten, S.; Fahl, K.; Polyak, L. V.; Cronin, T. M.; Bauch, H. A.; Sinninghe Damste, J. S.

    2013-12-01

    Sea surface temperature (SST) patterns in the northern North Atlantic, the Nordic seas, and the western Arctic Ocean (AO) were reconstructed across the MIS 11c interglacial, a potential future climate analogue, using planktic foraminiferal abundances, alkenone-based Uk'37 and glycerol dialkyl glycerol tetraether (GDGT)-based TEX86 analyses. Foraminiferal SST reconstructions were supported by foraminiferal counts of small-sized fractions and rare foraminiferal species, stable oxygen isotope measurements on benthic and planktic foraminifers, and ice rafted debris records. Additionally, the hydrogen isotopic (δD) compositions of long chain alkenones were determined to assess variations in paleo sea surface salinity in the North Atlantic. In the North Atlantic our newly produced TEX86 -based SSTs range between 14 and 19 °C in agreement with summer foraminiferal SST (13 and 18 °C) and alkenone SSTs (13 and 16 °C). However, the former showed higher fluctuations than SSTs based on foraminiferal abundances. In concordance with δ18O records TEX86 SSTs demonstrate notable variability in the middle of MIS 11c, between 400 and 410 ka, which is consistent with the intra-MIS 11c cold event in the Arctic indicated by planktic foraminifers. This pattern implies that the interglacial MIC 11c climate was probably not as stable as it widely believed. The preliminary alkenone δD data show that during MIS 11c salinity values in the North Atlantic were similar to Holocene values. Foraminiferal SST records imply that during MIS 11c at least parts of the AO experienced unusually warm and probably ice free conditions, whereas the Nordic seas remained rather cold, especially during the early phase of this period, as it is inferred from foraminiferal and alkenone SSTs. At the same time all our SST records show that the North Atlantic was 1-2°C warmer than present during MIS 11c. This pattern suggests that during MIS 11c the North Atlantic Current was deflected to the west, which

  16. Phylogenetic diversity and evolutionary relatedness of alkenone-producing haptophyte algae in lakes: Implications for continental paleotemperature reconstructions

    NASA Astrophysics Data System (ADS)

    Theroux, Susanna; D'Andrea, William J.; Toney, Jaime; Amaral-Zettler, Linda; Huang, Yongsong

    2010-12-01

    Alkenones have been found in an increasing number of lakes around the world, making them a promising new tool for continental paleoclimate reconstruction. However, individual lakes may harbor different species of haptophyte algae with different sensitivities to temperature variations, thus presenting a significant challenge to the use of lacustrine alkenones for paleotemperature reconstructions. To explore the extent of lacustrine haptophyte diversity, we conducted the first comprehensive phylogenetic and geochemical survey of lacustrine alkenone producers. We sampled 15 alkenone-containing lake surface sediments from a variety of geographic locales and inferred identities of environmental sequences using 18S ribosomal RNA (rRNA) gene-based phylogenies. For two lakes, BrayaSø in southwest Greenland and Tso Ur on the Tibetan Plateau, we also analyzed both surface and downcore sediments to characterize haptophyte populations through time. In parallel with phylogenetic analyses, we determined the alkenone distributions (including C 37/C 38 ratios, and the presence/absence of C 38 methyl ketones and C 40 compounds) in all the samples. The resulting alkenone profiles from this study do not all align with traditional "marine" versus "coastal/lacustrine" alkenone profiles. Additionally, our genetic data indicate the presence of multiple haptophyte species from a single lake sediment sample; these distinct haptophyte populations could not be discerned from the alkenone profiles alone. These results show that alkenone profiles are not a reliable way to assess the haptophyte algae in lakes and that DNA fingerprinting is a preferred approach for species identification. Although closely related haptophyte species or subspecies may not warrant different temperature calibrations, our results emphasize the importance of genetic data for inferring haptophyte identities and eventually selecting alkenone-temperature calibrations for paleoclimate reconstructions.

  17. Sea surface temperature variability in the Norwegian Sea during the late Pliocene linked to subpolar gyre strength and radiative forcing

    NASA Astrophysics Data System (ADS)

    Bachem, Paul E.; Risebrobakken, Bjørg; McClymont, Erin L.

    2016-07-01

    The mid-Piacenzian warm period (3.264-3.025 Ma) of the Pliocene epoch has been proposed as a possible reference for future warm climate states. However, there is significant disagreement over the magnitude of high latitude warming between data and models for this period of time, raising questions about the driving mechanisms and responsible feedbacks. We have developed a new set of orbital-resolution alkenone-based sea surface temperature (SST) and ice rafted debris (IRD) records from the Norwegian Sea spanning 3.264-3.14 Ma. The SSTs in the Norwegian Sea were 2-3 °C warmer than the Holocene average, likely caused by the radiative effect of higher atmospheric CO2 concentrations. There is notable obliquity-driven SST variability with a range of 4 °C, shown by evolutive spectra. The correlation of SST variability with the presence of IRD suggests a common climate forcing acting across the Nordic Seas region. Changes of the SST gradient between the Norwegian Sea and North Atlantic sites suggest that the subpolar gyre was at least as strong as during the Holocene, and that the northward heat transport by the North Atlantic Current was comparable.

  18. Sea Surface Salinity

    NASA Video Gallery

    The heat of the sun also forces evaporation at the ocean's surface, which puts water vapor into the atmosphere but leaves minerals and salts behind, keeping the ocean salty. The salinity of the oce...

  19. Tightly linked zonal and meridional sea surface temperature gradients over the past five million years

    NASA Astrophysics Data System (ADS)

    Fedorov, Alexey V.; Burls, Natalie J.; Lawrence, Kira T.; Peterson, Laura C.

    2015-12-01

    The climate of the tropics and surrounding regions is defined by pronounced zonal (east-west) and meridional (equator to mid-latitudes) gradients in sea surface temperature. These gradients control zonal and meridional atmospheric circulations, and thus the Earth’s climate. Global cooling over the past five million years, since the early Pliocene epoch, was accompanied by the gradual strengthening of these temperature gradients. Here we use records from the Atlantic and Pacific oceans, including a new alkenone palaeotemperature record from the South Pacific, to reconstruct changes in zonal and meridional sea surface temperature gradients since the Pliocene, and assess their connection using a comprehensive climate model. We find that the reconstructed zonal and meridional temperature gradients vary coherently over this time frame, showing a one-to-one relationship between their changes. In our model simulations, we systematically reduce the meridional sea surface temperature gradient by modifying the latitudinal distribution of cloud albedo or atmospheric CO2 concentration. The simulated zonal temperature gradient in the equatorial Pacific adjusts proportionally. These experiments and idealized modelling indicate that the meridional temperature gradient controls upper-ocean stratification in the tropics, which in turn controls the zonal gradient along the equator, as well as heat export from the tropical oceans. We conclude that this tight linkage between the two sea surface temperature gradients posits a fundamental constraint on both past and future climates.

  20. Long chain diol index (LDI) as an organic-based sea surface temperature proxy in the Korean East Sea (NW Pacific)

    NASA Astrophysics Data System (ADS)

    Gal, Jong-Ku; Kim, Jung-Hyun; Kang, Su-Jin; Lee, Dong-Hun; Shin, Kyung-Hoon

    2016-04-01

    Long chain diol index (LDI) was introduced as an organic-based sea surface temperature (SST) proxy. LDI is expressed as the C30 1,15-diol abundance relative to those of C28 1,13-, C30 1,13- and C30 1,15-diols. There were a few studies which accessed the potential of LDI based on the culture, core top sediments, suspended particulate organic matters, and down-core sediments. However it is still unknown about the source of the diols and robustness as the SST proxy in the various marine environments. In the current study, we examined the applicability of the LDI in the East Sea of Korea where productivity and thus sedimentation rates are high. We will compare the LDI data with those of alkenone-based UK'37 by analyzing two multicores covering the last 100 year.

  1. Sea surface temperature variability in the central-western Mediterranean Sea during the last 2700 years: a multi-proxy and multi-record approach

    NASA Astrophysics Data System (ADS)

    Cisneros, Mercè; Cacho, Isabel; Frigola, Jaime; Canals, Miquel; Masqué, Pere; Martrat, Belen; Casado, Marta; Grimalt, Joan O.; Pena, Leopoldo D.; Margaritelli, Giulia; Lirer, Fabrizio

    2016-04-01

    This study presents the reconstructed evolution of sea surface conditions in the central-western Mediterranean Sea during the late Holocene (2700 years) from a set of multi-proxy records as measured on five short sediment cores from two sites north of Minorca (cores MINMC06 and HER-MC-MR3). Sea surface temperatures (SSTs) from alkenones and Globigerina bulloides Mg / Ca ratios are combined with δ18O measurements in order to reconstruct changes in the regional evaporation-precipitation (E-P) balance. We also revisit the G. bulloides Mg / Ca-SST calibration and re-adjusted it based on a set of core-top measurements from the western Mediterranean Sea. Modern regional oceanographic data indicate that Globigerina bulloides Mg / Ca is mainly controlled by seasonal spring SST conditions, related to the April-May primary productivity bloom in the region. In contrast, the alkenone-SST signal represents an integration of the annual signal. The construction of a robust chronological framework in the region allows for the synchronization of the different core sites and the construction of "stacked" proxy records in order to identify the most significant climatic variability patterns. The warmest sustained period occurred during the Roman Period (RP), which was immediately followed by a general cooling trend interrupted by several centennial-scale oscillations. We propose that this general cooling trend could be controlled by changes in the annual mean insolation. Even though some particularly warm SST intervals took place during the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA) was markedly unstable, with some very cold SST events mostly during its second half. Finally, proxy records for the last centuries suggest that relatively low E-P ratios and cold SSTs dominated during negative North Atlantic Oscillation (NAO) phases, although SSTs seem to present a positive connection with the Atlantic Multidecadal Oscillation (AMO) index.

  2. Sea Surface Height 1993 - 2011

    NASA Video Gallery

    This animation depicts year-to-year variability in sea surface height, and chronicles two decades of El Niño and La Niña events. It was created using NASA ocean altimetry data from 1993 to 2011, ...

  3. MODIS Global Sea Surface Temperature

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  4. Changes in sea-surface conditions in the Equatorial Pacific during the middle Miocene-Pliocene (IODP Site 1338)

    NASA Astrophysics Data System (ADS)

    Rousselle, Gabrielle; Beltran, Catherine; Sicre, Marie-Alexandrine; Raffi, Isabella; De Rafélis, Marc

    2013-04-01

    The modern Equatorial Pacific setting is progressively developed during the Miocene and the Pliocene, with a gradual closure of the Central American Seaway (CAS) and the gradual constriction of the Indonesian seaway. In parallel, the Earth experienced a climatic transition from the mid-Miocene warm period to the modern "ice-house" climate with the growth of the Antarctic Ice-sheet (~ 13.9 Ma) and the appearance of large Northern Hemisphere Glaciations (NHG) (~ 3 Ma). In order to study the evolution of the Eastern equatorial Pacific (EEP) during the last 14 Myrs, we present here the Mio-Pliocene alkenone-derived curve, combined with the oxygen stable isotopes record of bulk carbonate (δ18Obulk) and calcareous nannofossils dominated fractions (δ18ONoelaerhabdaceae), from IODP Site 1338. The originality of this work lies in that the calcareous nannofossils species that are concentrated in the fine fractions belong to the same family to the alkenone producers. We are then able to compare an organic and an inorganic record from the same producer. Our data and those available from other sites of the same area show the extension of a cold tongue during the Early Pliocene (4.4-3.6 Ma). Indeed, our data suggest a shallowing of the thermocline in the EEP, between 6.8 and 6 Ma, and its shoaling between 4.8 and 4.0 Ma accompanying a sea surface cooling. Then, the timing of the thermocline shoaling does not agree with the idea that NHG initiated the Pliocene climate transition. SST and δ18ONoelaerhabdaceae time-series indicate periods of significant salinity variations. Then, comparison with the δ18OBenthic curve from sediment cores of the Equatorial Pacific Ocean allow us to distinguish between global changes and local salinity variations in the EEP, with a freshening between 11.5 and 10 Ma, and between 6.8 and 6 Ma. A pCO2 reconstruction based on δ13C of alkenone at site 1338 is currently measured and will eventually be presented, as well as TEX86 measurements in order

  5. Abrupt Sea Surface Temperature changes during The Last Glacial-Interglacial Transition in the Iberian margin: Sea Level implications

    NASA Astrophysics Data System (ADS)

    Rodrigues, Teresa; Grimalt, Joan; Abrantes, Fatima; Naughton, Filipa; Flores, José-Abel

    2010-05-01

    Uk'37-SST and organic terrestrial biomarkers were used to reconstruct Sea surface temperature (SST) and continental input in a shallow core (D13882) from the Tagus mud patch (Iberian margin) during last glacial and interglacial transition (LGIT). In the western Iberian margin the Heinrich 1 (H1) and the Younger Dryas (YD) represent two extreme episodes of cold sea surface temperature conditions mediated by a marine warm phase that coincides with the Bolling-Allerod event (B-A) in the neighbor continent. Following the YD event, an abrupt sea surface warming marks the beginning of the Holocene in this region. However, SST values and amplitude of variation recorded in core D13882 differ from deep sea core MD03- 2699 and other available palaeoclimate sequences from this region. While the SST values from most deep sea cores reflect the latitudinal gradient detected on the Iberian Peninsula during H1 and B-A, the shallow core (D13882) SSTs are colder than the ones recorded in the deep sea. This suggests that a supplementary input of cold freshwater coming from the continent reached shallow areas. This hypothesis is supported by the high terrigenous biomarkers and total organic carbon content as well as by the dominance of tetra alkenone in the Tagus mud patch. Furthermore, the comparison of all western Iberia SST records suggest that the SST increase during the B-A event started 1,000 yr before the meltwater pulse 1A (mwp-1A) and attained maximum values during or slightly after this sea level rise episode. Conversely, the sharp SST increase in the Iberian margin during the YD/Holocene transition, is synchronous with the meltwater pulse 1B (mwp-1B). The decrease of continental input in the Tagus mud patch confirms a sea level rise in the region. Thus, the synchronism between the maximum warming in the mid-latitudes of the western Iberian margin, in the adjacent landmasses and temperature in Greenland suggest that the mwp-1B, could have been initiated in the Northern

  6. Seasonal variations of alkenones and UK37 in the Chesapeake Bay water column

    USGS Publications Warehouse

    Mercer, J.L.; Zhao, M.; Colman, Steven M.

    2005-01-01

    Alkenone unsaturation indices (UK37 and U K???37) have long been used as proxies for surface water temperature in the open ocean. Recent studies have suggested that in other marine environments, variables other than temperature may affect both the production of alkenones and the values of the indices. Here, we present the results of a reconnaissance field study in which alkenones were extracted from particulate matter filtered from the water column in Chesapeake Bay during 2000 and 2001. A multivariate analysis shows a strong positive correlation between UK37 (and UK???37) values and temperature, and a significant negative correlation between UK37 (and UK???37) values and nitrate concentrations. However, temperature and nitrate concentrations also co-vary significantly. The temperature vs. UK37 relationships (UK37=0.018 (T)-0.162, R2=0.84, UK???37=0.013 (T)-0.04, R2=0.80) have lower slopes than the open-ocean equations of Prahl et al. [1988. Further evaluation of long-chain alkenones as indicators of paleoceanographic conditions. Geochimica et Cosmochimica Acta 52, 2303-2310] and Mu??ller et al. [1998. Calibration of the alkenone paleotemperature index UK???37 based on core-tops from the eastern South Atlantic and the global ocean (60??N-60??S). Geochimica et Cosmochimica Acta 62, 1757-1772], but are similar to the relationships found in controlled studies with elevated nutrient levels and higher nitrate:phosphate (N:P) ratios. This implies that high nutrient levels in Chesapeake Bay have either lowered the UK37 vs. temperature slope, or nutrient levels are the main controller of the U K37 index. In addition, particularly high abundances (>5% of total C37 alkenones) of the tetra-unsaturated ketone, C37:4, were found when water temperatures reached 25??C or higher, thus posing further questions about the controls on alkenone production as well as the biochemical roles of alkenones. ?? 2005 Elsevier Ltd. All rights reserved.

  7. Late Holocene primary productivity and sea surface temperature variations in the northeastern Arabian Sea: Implications for winter monsoon variability

    NASA Astrophysics Data System (ADS)

    Böll, Anna; Lückge, Andreas; Munz, Philipp; Forke, Sven; Schulz, Hartmut; Ramaswamy, V.; Rixen, Tim; Gaye, Birgit; Emeis, Kay-Christian

    2014-08-01

    Variability in the oceanic environment of the Arabian Sea region is strongly influenced by the seasonal monsoon cycle of alternating wind directions. Prominent and well studied is the summer monsoon, but much less is known about late Holocene changes in winter monsoon strength with winds from the northeast that drive convective mixing and high surface ocean productivity in the northeastern Arabian Sea. To establish a high-resolution record of winter monsoon variability for the late Holocene, we analyzed alkenone-derived sea surface temperature (SST) variations and proxies of primary productivity (organic carbon and δ15N) in a well-laminated sediment core from the Pakistan continental margin. Weak winter monsoon intensities off Pakistan are indicated from 400 B.C. to 250 A.D. by reduced productivity and relatively high SST. At about 250 A.D., the intensity of the winter monsoon increased off Pakistan as indicated by a trend to lower SST. We infer that monsoon conditions were relatively unstable from ~500 to 1300 A.D., because primary production and SST were highly variable. Declining SST and elevated biological production from 1400 to 1900 A.D. suggest invigorated convective winter mixing by strengthening winter monsoon circulation, most likely a regional expression of colder climate conditions during the Little Ice Age on the Northern Hemisphere. The comparison of winter monsoon intensity with records of summer monsoon intensity suggests that an inverse relationship between summer and winter monsoon strength exists in the Asian monsoon system during the late Holocene, effected by shifts in the Intertropical Convergence Zone.

  8. 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.

  9. Sea Surface Salinity : Research Challenges and Opportunities

    NASA Technical Reports Server (NTRS)

    Halpern, David; Lagerloef, Gary; Font, Jordi

    2012-01-01

    Sea surface salinity (SSS) can be important in regulating sea surface temperature (SST). Two technological breakthrough satellite SSS missions, Aquarius and Soil Moisture and Ocean Salinity (SMOS), are currently producing high-quality SSS data. This paper provides an overview of the importance of SSS for weather and climate applications and describes the Aquarius and SMOS missions. The newness of adequately sampled SSS data prompted a first-time at-sea field campaign devoted to improved understanding of SSS variations.

  10. Evidence For Inputs of Allochthonous Alkenones During The Last Glacial To The North Atlantic: Shortcomings In The Use of Alkenone Proxies In High Latitudes

    NASA Astrophysics Data System (ADS)

    Rosell-Melé, A.; Kornilova, O.; Russell, M.

    The reliability of UK37 to reconstruct SST in the Northern North Atlantic during the last glacial period has been already challenged in the literature. Thus, estimates of SST in cores located in latitudes higher than 50 degrees North appear to be unexpectedly warm if the conventional approach to use UK37 is followed (i.e. the relative abun- dance of the di and tri unsaturated alkenone converted to temperature using the equa- tion proposed by Prahl et al 1988, or Müller et al 1998). One of the feasible processes postulated to explain the unexpected warm estimates is to advocate the advection to the deep sea of allochthonous alkenones reflecting SSTs much warmer than those of the last glacial in high latitudes. However, no conclusive proof to date has been of- fered to demonstrate this hypothesis. To investigate this further we have examined the biomarker content of debris flows surrounding the northern North Atlantic. The last glacial ice sheets drained through specific outlet glaciers, giving rise to a number of large submarine fans in the continental margins. Large amounts of debris which had been entrained in the ice sheets were deposited at the shelf break. These sediments were inherently unstable, failed and were deposited on the slope through gravimet- ric mass flows (i.e. debris flows). We have found that some of the major debris flows contain alkenones in significant amounts. The composition of individual deposits is also homogenous both within a lobe and between lobes from the same area. More- over, those deposits in the Eastern Atlantic contain a SST-UK37 warm signal, devoid of tetraunsaturated C37 ketone, higher than those UK37 values found in modern sur- face sediments in the Northern North Atlantic. We argue that our findings prove that the estimates of SST derived from UK37 in glacial sediments of the northern north Atlantic are biased by an input of allochthonous alkenones transported by ice rafted debris.

  11. Late Eocene sea surface cooling of the western North Atlantic (ODP Site 647A)

    NASA Astrophysics Data System (ADS)

    Sliwinska, Kasia K.; Coxall, Helen K.; Schouten, Stefan

    2016-04-01

    The initial shift out of the early Cenozoic greenhouse and into a glacial icehouse climate occurred during the middle to late Eocene and culminated in the abrupt growth of a continental-scale ice cap on Antarctica, during an episode known as the Oligocene Isotope Event 1 (Oi-1) ˜33.7 Ma. Documenting the patterns of global and regional cooling prior to Oi-1 is crucial for understanding the driving force and feedback behind the switch in climate mode. Well-dated high-resolution temperature records, however, remain sparse and the climatic response in some of the most climatically sensitive regions of the Earth, including the high latitude North Atlantic (NA), where today large amounts of ocean heat are exchanged, are poorly known. Here we present a sea surface palaeotemperature record from the late Eocene to the early Oligocene (32.5 Ma to 35 Ma) of ODP Hole 647A based on archaeal tetraether lipids (TEX86H). The site is located in the western North Atlantic (Southern Labrador Sea) and is the most northerly located (53° N) open ocean site with a complete Eocene-Oligocene sequence which yields both calcareous and organic microfossils suitable for detailed proxy reconstructions. Our record agrees with the magnitude of temperature decrease (˜3 ° C sea surface cooling) recorded by alkenones and pollen data from the Greenland Sea, but our higher resolution study reveals that the high latitude NA cooling step occurred about 500 kyrs prior to the Oi-1 Antarctic glaciation, at around ˜34.4 Ma. This cooling can be explained by regional effects related to local NA tectonics including ocean gateways, known to have changed at the time, with potential to effect NA overturning circulation due to adjustments in the thermohaline density balance. Alternatively, the cooling itself may be due to changes in NA circulation, suggesting that global ocean circulation played a role in pre-conditioning the Earth for Antarctic glaciation.

  12. Mid-Piacensian mean annual sea surface temperature: an analysis for data-model comparisons

    USGS Publications Warehouse

    Dowsett, Harry J.; Robinson, Marci M.; Foley, Kevin M.; Stoll, Danielle K.

    2010-01-01

    Numerical models of the global climate system are the primary tools used to understand and project climate disruptions in the form of future global warming. The Pliocene has been identified as the closest, albeit imperfect, analog to climate conditions expected for the end of this century, making an independent data set of Pliocene conditions necessary for ground truthing model results. Because most climate model output is produced in the form ofmean annual conditions, we present a derivative of the USGS PRISM3 Global Climate Reconstruction which integrates multiple proxies of sea surface temperature (SST) into single surface temperature anomalies. We analyze temperature estimates from faunal and floral assemblage data,Mg/Ca values and alkenone unsaturation indices to arrive at a single mean annual SST anomaly (Pliocene minus modern) best describing each PRISM site, understanding that multiple proxies should not necessarily show concordance. The power of themultiple proxy approach lies within its diversity, as no two proxies measure the same environmental variable. This data set can be used to verify climate model output, to serve as a starting point for model inter-comparisons, and for quantifying uncertainty in Pliocene model prediction in perturbed physics ensembles.

  13. Mid-Pliocene equatorial Pacific sea surface temperature reconstruction: A multi-proxy perspective

    USGS Publications Warehouse

    Dowsett, H.J.; Robinson, M.M.

    2009-01-01

    The Mid-Pliocene is the most recent interval of sustained global warmth, which can be used to examine conditions predicted for the near future. An accurate spatial representation of the low-latitude Mid-Pliocene Pacific surface ocean is necessary to understand past climate change in the light of forecasts of future change. Mid-Pliocene sea surface temperature (SST) anomalies show a strong contrast between the western equatorial Pacific (WEP) and eastern equatorial Pacific (EEP) regardless of proxy (faunal, alkenone and Mg/Ca). All WEP sites show small differences from modern mean annual temperature, but all EEP sites show significant positive deviation from present-day temperatures by as much as 4.4??C. Our reconstruction reflects SSTs similar to modern in the WEP, warmer than modern in the EEP and eastward extension of the WEP warm pool. The east-west equatorial Pacific SST gradient is decreased, but the pole to equator gradient does not change appreciably. We find it improbable that increased greenhouse gases (GHG) alone would cause such a heterogeneous warming and more likely that the cause of Mid-Pliocene warmth is a combination of several forcings including both increased meridional heat transport and increased GHG. ?? 2008 The Royal Society.

  14. Mid-Pliocene equatorial Pacific sea surface temperature reconstruction: a multi-proxy perspective

    USGS Publications Warehouse

    Dowsett, Harry J.; Robinson, Marci M.

    2009-01-01

    The Mid-Pliocene is the most recent interval of sustained global warmth, which can be used to examine conditions predicted for the near future. An accurate spatial representation of the low-latitude Mid-Pliocene Pacific surface ocean is necessary to understand past climate change in the light of forecasts of future change. Mid-Pliocene sea surface temperature (SST) anomalies show a strong contrast between the western equatorial Pacific (WEP) and eastern equatorial Pacific (EEP) regardless of proxy (faunal, alkenone and Mg/Ca). All WEP sites show small differences from modern mean annual temperature, but all EEP sites show significant positive deviation from present-day temperatures by as much as 4.4°C. Our reconstruction reflects SSTs similar to modern in the WEP, warmer than modern in the EEP and eastward extension of the WEP warm pool. The east-west equatorial Pacific SST gradient is decreased, but the pole to equator gradient does not change appreciably. We find it improbable that increased greenhouse gases (GHG) alone would cause such a heterogeneous warming and more likely that the cause of Mid-Pliocene warmth is a combination of several forcings including both increased meridional heat transport and increased GHG.

  15. Aquarius Observations of Sea Surface Salinity

    NASA Video Gallery

    This visualization shows changes in global sea surface salinity, as measured by NASA’s Aquarius instrument aboard the Aquarius/SAC-D spacecraft, from December 2011 through December 2012. Red repr...

  16. Problems in determining sea surface topography

    NASA Technical Reports Server (NTRS)

    Whitehead, J. A., Jr.

    1978-01-01

    Anticipated problems for determining ocean dynamics signals from sea surface topography are discussed. The needs for repeated tracks are listed if oceanic tides or ocean turbulence are to be determined.

  17. Testing the D / H ratio of alkenones and palmitic acid as salinity proxies in the Amazon Plume

    NASA Astrophysics Data System (ADS)

    Häggi, C.; Chiessi, C. M.; Schefuß, E.

    2015-12-01

    The stable hydrogen isotope composition of lipid biomarkers, such as alkenones, is a promising new tool for the improvement of palaeosalinity reconstructions. Laboratory studies confirmed the correlation between lipid biomarker δD composition (δDLipid), water δD composition (δDH2O) and salinity; yet there is limited insight into the applicability of this proxy in oceanic environments. To fill this gap, we test the use of the δD composition of alkenones (δDC37) and palmitic acid (δDPA) as salinity proxies using samples of surface suspended material along the distinct salinity gradient induced by the Amazon Plume. Our results indicate a positive correlation between salinity and δDH2O, while the relationship between δDH2O and δDLipid is more complex: δDPAM correlates strongly with δDH2O (r2 = 0.81) and shows a salinity-dependent isotopic fractionation factor. δDC37 only correlates with δDH2O in a small number (n = 8) of samples with alkenone concentrations > 10 ng L-1, while there is no correlation if all samples are taken into account. These findings are mirrored by alkenone-based temperature reconstructions, which are inaccurate for samples with low alkenone concentrations. Deviations in δDC37 and temperature are likely to be caused by limited haptophyte algae growth due to low salinity and light limitation imposed by the Amazon Plume. Our study confirms the applicability of δDLipid as a salinity proxy in oceanic environments. But it raises a note of caution concerning regions where low alkenone production can be expected due to low salinity and light limitation, for instance, under strong riverine discharge.

  18. Implication of methodological uncertainties for mid-Holocene sea surface temperature reconstructions

    NASA Astrophysics Data System (ADS)

    Hessler, I.; Harrison, S. P.; Kucera, M.; Waelbroeck, C.; Chen, M.-T.; Anderson, C.; de Vernal, A.; Fréchette, B.; Cloke-Hayes, A.; Leduc, G.; Londeix, L.

    2014-12-01

    We present and examine a multi-sensor global compilation of mid-Holocene (MH) sea surface temperatures (SST), based on Mg/Ca and alkenone palaeothermometry and reconstructions obtained using planktonic foraminifera and organic-walled dinoflagellate cyst census counts. We assess the uncertainties originating from using different methodologies and evaluate the potential of MH SST reconstructions as a benchmark for climate-model simulations. The comparison between different analytical approaches (time frame, baseline climate) shows the choice of time window for the MH has a negligible effect on the reconstructed SST pattern, but the choice of baseline climate affects both the magnitude and spatial pattern of the reconstructed SSTs. Comparison of the SST reconstructions made using different sensors shows significant discrepancies at a regional scale, with uncertainties often exceeding the reconstructed SST anomaly. Apparent patterns in SST may largely be a reflection of the use of different sensors in different regions. Overall, the uncertainties associated with the SST reconstructions are generally larger than the MH anomalies. Thus, the SST data currently available cannot serve as a target for benchmarking model simulations. Further evaluations of potential subsurface and/or seasonal artifacts that may contribute to obscure the MH SST reconstructions are urgently needed to provide reliable benchmarks for model evaluations.

  19. Implication of methodological uncertainties for Mid-Holocene sea surface temperature reconstructions

    NASA Astrophysics Data System (ADS)

    Hessler, I.; Harrison, S. P.; Kucera, M.; Waelbroeck, C.; Chen, M.-T.; Andersson, C.; de Vernal, A.; Fréchette, B.; Cloke-Hayes, A.; Leduc, G.; Londeix, L.

    2014-04-01

    We present and examine a~multi-sensor global compilation of Mid-Holocene (MH) sea surface temperatures (SSTs), based on Mg/Ca and alkenone palaeothermometry and reconstructions obtained using planktonic foraminifera and organic-walled dinoflagellate cyst census counts. We assess the uncertainties originating from using different methodologies and evaluate the potential of MH SST reconstructions as a benchmark for climate-model simulations. The comparison between different analytical approaches (time frame, baseline climate) shows the choice of time window for the MH has a negligible effect on the reconstructed SST pattern, but the choice of baseline climate affects both the magnitude and spatial pattern of the reconstructed SSTs. Comparison of the SST reconstructions made using different sensors shows significant discrepancies at a regional scale, with uncertainties often exceeding the reconstructed SST anomaly. Apparent patterns in SST may largely be a reflection of the use of different sensors in different regions. Overall, the uncertainties associated with the SST reconstructions are generally larger than the MH anomalies. Thus, the SST data currently available cannot serve as a target for benchmarking model simulations.

  20. Anomalous sea surface reverberation scale model experiments.

    PubMed

    Neighbors, T H; Bjørnø, L

    2006-12-22

    Low frequency sea surface sound backscattering from approximately 100 Hz to a few kHz observed from the 1960s broadband measurements using explosive charges to the Critical Sea Test measurements conducted in the 1990 s is substantially higher than explained by rough sea surface scattering theory. Alternative theories for explaining this difference range from scattering by bubble plumes/clouds formed by breaking waves to stochastic scattering from fluctuating bubble layers near the sea surface. In each case, theories focus on reverberation in the absence of the large-scale surface wave height fluctuations that are characteristic of a sea that produces bubble clouds and plumes. At shallow grazing angles, shadowing of bubble plumes and clouds caused by surface wave height fluctuations may induce first order changes in the backscattered signal strength. To understand the magnitude of shadowing effects under controlled and repeatable conditions, scale model experiments were performed in a 3 m x 1.5 m x 1.5 m tank at the Technical University of Denmark. The experiments used a 1 MHz transducer as the source and receiver, a computer controlled data acquisition system, a scale model target, and a surface wave generator. The scattered signal strength fluctuations observed at shallow angles are characteristic of the predicted ocean environment. These experiments demonstrate that shadowing has a first order impact on bubble plume and cloud scattering strength and emphasize the usefulness of model scale experiments for studying underwater acoustic events under controlled conditions.

  1. 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.

  2. Holocene interdependences of changes in sea surface temperature, productivity, and fluvial inputs in the Iberian continental shelf (Tagus mud patch)

    NASA Astrophysics Data System (ADS)

    Rodrigues, Teresa; Grimalt, Joan O.; Abrantes, FáTima G.; Flores, Jose A.; Lebreiro, Susana M.

    2009-07-01

    Sea surface temperature (SST), marine productivity, and fluvial input have been reconstructed for the last 11.5 calendar (cal) ka B.P. using a high-resolution study of C37 alkenones, coccolithophores, iron content, and higher plant n-alkanes and n-alkan-1-ols in sedimentary sequences from the inner shelf off the Tagus River Estuary in the Portuguese Margin. The SST record is marked by a continuous decrease from 19°C, at 10.5 and 7 ka, to 15°C at present. This trend is interrupted by a fall from 18°C during the Roman and Medieval Warm Periods to 16°C in the Little Ice Age. River input was very low in the early Holocene but increased in the last 3 cal ka B.P. in association with an intensification of agriculture and deforestation and possibly the onset of the North Atlantic Oscillation/Atlantic Multidecadal Oscillation modes of variability. River influence must have reinforced the marine cooling trend relative to the lower amplitude in similar latitude sites of the eastern Atlantic. The total concentration of alkenones reflects river-induced productivity, being low in the early Holocene but increasing as river input became more important. Rapid cooling, of 1-2°C occurring in 250 years, is observed at 11.1, 10.6, 8.2, 6.9, and 5.4 cal ka B.P. The estimated age of these events matches the ages of equivalent episodes common in the NE Atlantic-Mediterranean region. This synchronicity reveals a common widespread climate feature, which considering the twentieth century analog between colder SSTs and negative North Atlantic Oscillation (NAO), is likely to reflect periods of strong negative NAO.

  3. The last glacial-interglacial transition (LGIT) in the western mid-latitudes of the North Atlantic: Abrupt sea surface temperature change and sea level implications

    NASA Astrophysics Data System (ADS)

    Rodrigues, Teresa; Grimalt, Joan O.; Abrantes, Fátima; Naughton, Filipa; Flores, José-Abel

    2010-07-01

    High resolution reconstructions of sea surface temperature (U k'37-SST), coccolithophore associations and continental input (total organic carbon, higher plant n-alkanes, n-alkan-1-ols) in core D13882 from the shallow Tagus mud patch are compared to SST records from deep-sea core MD03-2699 and other western Iberian Margin cores. Results reveal millennial-scale climate variability over the last deglaciation, in particular during the LGIT. In the Iberian margin, Heinrich event 1 (H1) and the Younger Dryas (YD) represent two extreme episodes of cold sea surface condition separated by a marine warm phase that coincides with the Bølling-Allerød interval (B-A) on the neighboring continent. Following the YD event, an abrupt sea surface warming marks the beginning of the Holocene in this region. SSTs recorded in core D13882 changed, however, faster than those at deep-sea site MD03-2699 and at the other available palaeoclimate sequences from the region. While the SST values from most deep-sea cores reflect the latitudinal gradient detected in the Iberian Peninsula atmospheric temperature proxies during H1 and the B-A, the Tagus mud patch (core D13882) experienced colder SSTs during both events. This is most certainly related to a supplementary input of cold freshwater from the continent to the Tagus mud patch, a hypothesis supported by the high contents of terrigenous biomarkers and total organic carbon as well as by the dominance of tetra-unsaturated alkenone (C 37:4) observed at this site. The comparison of all western Iberia SST records suggests that the SST increase that characterizes the B-A event in this region started 1000 yr before meltwater pulse 1A (mwp-1A) and reached its maximum values during or slightly after this episode of substantial sea-level rise. In contrast, during the YD/Holocene transition, the sharp SST rise in the Tagus mud patch is synchronous with meltwater pulse 1B. The decrease of continental input to the mud patch confirms a sea level rise in

  4. Tropical sea surface temperature variability near the Oligocene - Miocene boundary

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Pagani, M.

    2010-12-01

    The Oligocene/Miocene (O-M) boundary is characterized by a period of rapid and intense glaciation labeled Mi-1 at ~ 23.1 Ma. An abrupt 1.5‰ increase in the benthic foraminifera oxygen isotope composition that characterizes Mi-1 may indicate a (1) significant deep-water temperature decrease; (2) major ice-sheet expansion, or the combination of both. Current coarse Mg/Ca-based temperature estimations for the early Miocene suggests that deep-ocean temperatures were ~2°C warmer than Today [1, 2]. However, Mg/Ca based temperatures can also be influenced by changes in the carbonate ion concentration, vital effects, and diagenesis. In particular, recent evidence from mid-ocean ridge flank carbonate veins shows dramatic seawater Mg/Ca ratio changes during the Neogene (Mg/Ca from ~2.2 to 5.3, [3]), which further challenges the application of Mg/Ca thermometry. Owing to poor temperature constraints, current ice volume estimations for the late Oligocene/early Miocene range from 125% of the present-day East Antarctic Ice Sheet (EAIS) to a nearly complete collapse of the Antarctic glaciers [4]. Here we present tropical sea surface temperatures (SSTs) records based on TEX86 and alkenone UK37 near the O-M boundary. Sediment samples from Ocean Drilling Program (ODP) Site 926 in the Ceara Rise (tropical Atlantic) and Site 1148 in the South China Sea (tropical Pacific) were subject to lipid extraction, separation, gas chromatography, and liquid chromatography-mass spectrometry analysis. TEX86-based SST indicates that the tropics were ~3-4°C warmer than today and relatively stable during Mi-1. This suggests that ice-sheet dynamics, rather than temperature, might be responsible for the observed oxygen isotope changes during the O-M boundary. Further, O-M boundary averaged temperatures recorded at site 926 is ~ 0.5°C higher relative to the late Eocene from site 925 (a nearby site [5]). Given late Oligocene benthic δ18O that suggests at least 1‰ enrichment relative to the late

  5. Refining the alkenone-pCO2 method: The role of algal growth conditions

    NASA Astrophysics Data System (ADS)

    Pearson, A.; Zhang, Y.; Huybers, P. J.; Pagani, M.

    2015-12-01

    The alkenone-pCO2 method based on carbon isotope fractionation during growth of haptophyte algae is one of the most widely used approaches to reconstruct atmospheric CO2 level in the Cenozoic. Based on the fractionation of stable carbon isotopes between dissolved CO2 and phytoplankton biomass, as represented by alkenone lipid biomarkers, this relationship (known as ɛp37:2) scales inversely with growth rate and cell volume to surface area ratio, and positively with CO2. Recently-published estimates for late Pleistocene CO2 levels, however, are poorly correlated with ice core CO2 records, suggesting that alkenone paleobarometry needs to be refined. Here we compiled published records over recent glacial-interglcial (G-IG) cycles and revised the relationship between algal growth rate, as expressed by the physiological parameter 'b', and dissolved phosphate concentration. We further show that the magnitude of change in ɛp37:2 over glacial-interglacial cycles at different sites is dependent on local nutrient conditions, highlighting the importance of constraining b for accurate CO2 estimates. The correlation between GDGT-2/3 ratio and back-calculated b at Ceara Rise (ODP Site 925) suggests that archaeal lipids could be used as proxies to calibrate b. Application of our variable-b method to reported data yields pCO2 estimates that are similar in both trends and magnitude to ice core-derived records.

  6. Precise orbit computation and sea surface modeling

    NASA Technical Reports Server (NTRS)

    Wakker, Karel F.; Ambrosius, B. A. C.; Rummel, R.; Vermaat, E.; Deruijter, W. P. M.; Vandermade, J. W.; Zimmerman, J. T. F.

    1991-01-01

    The research project described below is part of a long-term program at Delft University of Technology aiming at the application of European Remote Sensing satellite (ERS-1) and TOPEX/POSEIDON altimeter measurements for geophysical purposes. This program started in 1980 with the processing of Seasat laser range and altimeter height measurements and concentrates today on the analysis of Geosat altimeter data. The objectives of the TOPEX/POSEIDON research project are the tracking of the satellite by the Dutch mobile laser tracking system MTLRS-2, the computation of precise TOPEX/POSEIDON orbits, the analysis of the spatial and temporal distribution of the orbit errors, the improvement of ERS-1 orbits through the information obtained from the altimeter crossover difference residuals for crossing ERS-1 and TOPEX/POSEIDON tracks, the combination of ERS-1 and TOPEX/POSEIDON altimeter data into a single high-precision data set, and the application of this data set to model the sea surface. The latter application will focus on the determination of detailed regional mean sea surfaces, sea surface variability, ocean topography, and ocean currents in the North Atlantic, the North Sea, the seas around Indonesia, the West Pacific, and the oceans around South Africa.

  7. Characteristics of networks in sea surface temperatures

    NASA Astrophysics Data System (ADS)

    Jung, W.; Lee, D.; Kim, K.

    2012-04-01

    The climate of each nation is affected by meteorological factors such as rainfall, temperature, humidity, and wind. The sea surface temperature has played a crucial role in the climate change of continents. In IPCC report, when the temperature is increased by the climate change, it has influence on the earth's warming. The variation of sea surface temperatures is known to cause the atmospheric circulation, El Niño, and La Niña because the ocean comprises a large portion of the global surface. It is hence important for our research to simulate and analyze the change of sea surface temperatures on the Atlantic, Indian and Pacific oceans. In this paper, we firstly investigate the dynamical behavior of sea surface temperatures via the rescaled range analysis according to the season. Secondly, we analyze in detail the topological property of sea surface temperatures connecting to the network theory. We use the merged satellite and in-situ data global daily sea surface temperature data provided from the Japan meteorological agency and the data of sea surface temperatures are collected during five years from January 2005 to December 2009. In our method, we segment one region (a case of a restricted area among three oceans) into cells, each of which has the same area, viz. one cell area is 0.25 degree latitude × 0.25 degree longitude. The center of each cell is regarded as a node on the network, and the network is basically constructed as the values appertaining to the same ranges for the Hurst exponent values. By reconsidering a 4-by-4 cell (1 degree latitude × 1 degree longitude) as a new node, the number of links is counted as one node if the two (or more) links overlap between cells. We also can make up the topological property of the complex network in one region. Then we can extend it to the three oceans. Consequently, we find the hub points of the SST on the Atlantic, Indian and Pacific oceans, but it is necessary to analyze rigorously the network of the SST. In

  8. Climate modulation on sea surface height in China seas

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoshuang; Wang, Xidong; Cao, Yingzhi; Zhang, Lianxin; Shao, Caixia; Sun, Chunjian; Wu, Xinrong; Fu, Hongli; Xuan, Lili

    2015-09-01

    The climate modulation on the sea surface height (SSH) in China seas is investigated using a China Ocean Reanalysis (CORA) dataset from 1958-2008. The dataset is constructed by assimilating the temperature/salinity profiles derived from the satellite altimetry data and historical observational temperature/salinity profiles. Based on the Empirical Orthogonal Function (EOF), the CORA sea surface height anomaly (SSHa) is decomposed, and the interannual and decadal variability of the first three leading modes are analyzed. On the interannual timescale, the first principal component (PC1) is significant positively correlated with the El Niño/Southern Oscillation (ENSO). On the decadal timescale, North Pacific Gyre Oscillation (NPGO) has significant negative correlation with PC1 whereas Pacific Decadal Oscillation (PDO) is in phase with PC3. Analysis shows that the decadal variability of SSH is mainly modulated by the wind stress curl variability related to the NPGO and PDO. In addition, the effect of net heat flux associated to the NPGO and PDO on SSH is also investigated, with net heat flux variability in the Luzon strait and tropic Pacific found to influence the decadal variability of SSH.

  9. Climatic influences on the Paleogene evolution of alkenones

    NASA Astrophysics Data System (ADS)

    Brassell, Simon C.

    2014-03-01

    Application of the alkenone paleotemperature proxy (UK'37) for marine sediments is typically constrained by three factors: (i) an absence of alkatrienones in sediments deposited where ocean temperatures exceed ~28°C, (ii) loss of alkenones in thermally altered sediments, and (iii) poor preservation of alkenone signals due to oxidative degradation. In addition, there appears to be a temporal limit on the occurrence of alkatrienones, which are conspicuously absent in all alkenone-containing sediments from the early Aptian to the immediate aftermath of the Early Eocene Climatic Optimum (EECO) when they first appeared in Arctic Ocean sediments. Compilation of reported and previously unpublished alkenone distributions for the Paleogene coupled with assessment of co-occurring calcareous nannoplankton genera within the Noelaerhabdaceae provide evidence that evolutionary developments in alkenone occurrences include biosynthetic responses likely triggered by climate change. The timing of emergence of alkatrienones post-EECO and their subsequent appearance at all latitudes during the middle Eocene accompanies expansion of the calcareous nannoplankton genus Reticulofenestra coincident with significant climate-driven changes in oceanic conditions, including (i) modification of trophic structure associated with weakened thermal stratification, (ii) higher productivity facilitated by enhanced nutrient influx, and (iii) changes in seasonality, initially at high latitudes, related to greater latitudinal temperature gradients. Collectively, these changes would serve to favor eurythermal/eurytrophic algae, like Reticulofenestra, with a biomechanism to store energy through production of lipid bodies rich in alkenones during episodes of higher nutrient availability. This ability likely enhanced the viability of this marine haptophyte when nutrients were limiting, ultimately ensuring its evolutionary success.

  10. Long-chain alkenones and U 37k' variability along a south-north transect in the Western Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Bentaleb, Ilhem; Fontugne, Michel; Beaufort, Luc

    2002-11-01

    In this paper, we present 50 surface water samples collected during the IMAGES III cruise (June-July 1997) along a transect from New Zealand to the China Sea (42°S-178°E, 21°N-120°E) covering a temperature range from 13.3 to 30.4 °C. A very worthwhile aspect of this study is a coupling of both biomarker (alkenone) and coccolithophorid counting. We show that the U 37k'-temperature relationship is very similar to the Prahl et al. [Geochim. Cosmochim. Acta 52 (1988) 2203] culture calibration and to the global core top calibration of Müller et al. [Geochim. Cosmochim. Acta 62 (1998) 1757]. However, in the warmest surface waters of the Western Pacific ocean (>26.4 °C) where Gephyrocapsa oceanica is likely the most widespread species, the associated U 37k' has a constant value of 1.0. The consequence is that above this temperature threshold, U 37k' cannot be used as an accurate paleothermometer.

  11. Three modes of interdecadal trends in sea surface temperature and sea surface height

    NASA Astrophysics Data System (ADS)

    Gnanadesikan, A.; Pradal, M.

    2013-12-01

    It might be thought that sea surface height and sea surface temperature would be tightly related. We show that this is not necessarily the case on a global scale. We analysed this relationship in a suite of coupled climate models run under 1860 forcing conditions. The models are low-resolution variants of the GFDL Earth System Model, reported in Galbraith et al. (J. Clim. 2011). 1. Correlated changes in global sea surface height and global sea surface temperature. This mode corresponds to opening and closing of convective chimneys in the Southern Ocean. As the Southern Ocean destratifies, sea ice formation is suppressed during the winter and more heat is taken up during the summer. This mode of variability is highly correlated with changes in the top of the atmosphere radiative budget and weakly correlated with changes in the deep ocean circulation. 2. Uncorrelated changes in global sea surface height and global sea surface temperature. This mode of variability is associated with interdecadal variabliity in tropical winds. Changes in the advective flux of heat to the surface ocean play a critical role in driving these changes, which also result in significant local changes in sea level. Changes sea ice over the Southern Ocean still result in changes in solar absorption, but these are now largely cancelled by changes in outgoing longwave radiation. 3. Anticorrelated changes in global sea surface height and global sea surface temperatures. By varying the lateral diffusion coefficient in the ocean model, we are able to enhance and suppress convection in the Southern and Northern Pacific Oceans. Increasing the lateral diffusion coefficients shifts the balance sources of deep water away from the warm salty deep water of the North Atlantic and towards cold fresh deep water from the other two regions. As a result, even though the planet as a whole warms, the deep ocean cools and sea level falls, with changes of order 30 cm over 500 years. The increase in solar absorption

  12. Satellite monitoring of sea surface pollution

    NASA Technical Reports Server (NTRS)

    Fielder, G.; Telfer, D. J. (Principal Investigator)

    1979-01-01

    The author has identified the following significant results. Image processing techniques developed are well adapted to the exploration and isolation of local areas which exhibit small temperature differences between themselves and their surroundings. In the worst case of imagery of small areal extent of sea surface having no coastal boundary in the area, there is yet no method of distinguishing unambiguously an oil spill from fog, cloud, the effect produced by shallow sediments, or the effects of naturally occuring thermal fronts. In the case of uniform slicks of liquid North Sea oil in still air, laboratory simulation experiments show that, for oil thicknesses in excess of 1 or 2 mm, there is, under equilibrium conditions, little dependence of oil surface temperature on the thickness of the oil layer. The surface temperature of oil is consistently higher than that of water, the difference being about 1 K at low values of relative humidity, but tending to increase as the relative humidity increases.

  13. Enhanced stratification and seasonality in the Subarctic Pacific upon Northern Hemisphere Glaciation-New evidence from diatom-bound nitrogen isotopes, alkenones and archaeal tetraethers

    NASA Astrophysics Data System (ADS)

    Studer, Anja S.; Martínez-Garcia, Alfredo; Jaccard, Samuel L.; Girault, France E.; Sigman, Daniel M.; Haug, Gerald H.

    2012-10-01

    Coincident with the intensification of Northern Hemisphere Glaciation (NHG) around 2.73 million years (Ma) ago, sediment cores from both the open subarctic North Pacific and the Antarctic indicate a rapid decline in diatom opal accumulation flux to the seabed, representing one of the most abrupt and dramatic changes in the marine sediment record associated with the development of Pleistocene glacial cycles. In the North Pacific, bulk sediment nitrogen isotope data and alkenone-derived sea surface temperature (SST) estimates suggest that the productivity decline was driven by reduced exchange between surface and deep water, due to weaker wind-driven upwelling and/or a strengthening of the halocline (i.e. "stratification"). In this study of the 2.73 Ma transition at Ocean Drilling Program (ODP) Site 882 in the western subarctic North Pacific, diatom-bound nitrogen isotopes (δ15Ndb), alkenone mass accumulation rate, and alkenone- and archaeal tetraether-based SST reconstructions support the stratification hypothesis, indicating perennially lower export production, generally higher nitrate consumption, and greater inter-seasonal variation in SST after the 2.73 Ma transition. In addition, the δ15Ndb of large and small size fractions of Coscinodiscus spp. suggest that these diatoms grew mostly during the spring bloom during the late Pliocene, switching to their current fall-to-winter growth period at the 2.73 Ma transition; this view is consistent with their decline in dominance and provides further evidence for increased stratification (reduced vertical exchange) in the North Pacific after 2.73 Ma. The δ15Ndb data indicate that, over the ˜100 kyr period after the 2.73 Ma transition studied here, nitrate consumption did not reach late Pleistocene ice age levels and that nitrate consumption in post-2.73 Ma warm stages was similar to that before the transition, even though productivity was greatly reduced. We tentatively attribute this to relatively weak dust

  14. Global mean sea surface based upon SEASAT altimeter data

    NASA Technical Reports Server (NTRS)

    Marsh, J. G.

    1984-01-01

    A global mean sea surface based upon the SEASAT altimeter data was derived. A combination of crossing arc techniques, accurate SEASAT reference orbits, and a previously computed GOES-3/SEASAT mean sea surface were used in the computation process. This mean sea surface provides a basis for the determination of global ocean circulation patterns and for detailed analysis of the Earth's internal structure. A contour map of the global mean sea surface is presented.

  15. Is the lycopane/n-C31 ratio an effective proxy of palaeoxicity of bottom water for the Japan Sea? - Unusual distribution of lycopane in the surface sediment from the Japan Sea collected by the MD179 cruise

    NASA Astrophysics Data System (ADS)

    Ogihara, Shigenori

    2014-08-01

    The lycopane/n-C31 ratio has been proposed as a proxy of palaeoxicity of bottom water. To assess its applicability in the Japan Sea, the piston core samples of MD179-3312, which contains several dark layers that are known to deposited when the bottom water had low oxygen contents, were geochemically analyzed. The TL2 and TL3 layers, deposited during the last glacial maximum when the Japan Sea was stratified, did not show a high lycopane/n-C31 ratio. In contrast, the TL1 layer, which was deposited when the Japan Sea stagnated temporarily but the surface ocean became increasingly productive, had a high lycopane/n-C31 ratio. Furthermore, the depth profile of lycopane/n-C31 ratio is similar to that of n-C37 alkadiene, a compound potentially related to alkenones. Accordingly, we concluded that the lycopane/n-C31 ratio is not a useful proxy to assess palaeoxicity of the bottom water, but reflects the productivity of some phytoplankton in the Japan Sea. This study was supported by MH21, Research Consortium for Methane Hydrate Resources in Japan.

  16. Twentieth-Century Sea Surface Temperature Trends

    PubMed

    Cane; Clement; Kaplan; Kushnir; Pozdnyakov; Seager; Zebiak; Murtugudde

    1997-02-14

    An analysis of historical sea surface temperatures provides evidence for global warming since 1900, in line with land-based analyses of global temperature trends, and also shows that over the same period, the eastern equatorial Pacific cooled and the zonal sea surface temperature gradient strengthened. Recent theoretical studies have predicted such a pattern as a response of the coupled ocean-atmosphere system to an exogenous heating of the tropical atmosphere. This pattern, however, is not reproduced by the complex ocean-atmosphere circulation models currently used to simulate the climatic response to increased greenhouse gases. Its presence is likely to lessen the mean 20th-century global temperature change in model simulations. PMID:9020074

  17. [Multiple scattering of visible and infrared light by sea fog over wind driving rough sea surface].

    PubMed

    Sun, Xian-Ming; Wang, Hai-Hua; Lei, Cheng-Xin; Shen, Jin

    2013-08-01

    The present paper is concerned with computing the multiple scattering characteristics of a sea fog-sea surface couple system within this context. The single scattering characteristics of sea fog were studied by Mie theory, and the multiple scattering of sunlight by single sea fog layer was studied by radiative transfer theory. The reflection function of a statistically rough ocean surface was obtained using the standard Kirchhoff formulation, with shadowing effects taken into account. The reflection properties of the combined sea fog and ocean surface were obtained employing the adding method, and the results indicated that the reflected light intensity of sea fog increased with the sea background.

  18. Droughts in the Miocene of the Black Sea region

    NASA Astrophysics Data System (ADS)

    Vasiliev, Iuliana; Reichart, Gert-Jan; Grothe, Arjen; Krijgsman, Wout

    2016-04-01

    Since Miocene the Black Sea has been highly sensitive to fluctuations in the hydrological cycle. These fluctuations were principally determined by Black Sea's recurrently restricted connections to the Open Ocean and by its specific paleogeographic location between the dry Mediterranean domain and more humid higher northern latitudes. To determine the nature of changes in the hydrological budget of the Black Sea occurring during the late Miocene we use compound-specific hydrogen isotope ratios on terrestrial and aquatic biomarkers extracted from two different locations: 1) the sedimentary succession of Zhelezniy Rog land based section of Taman in Russia and 2) the deep sea sedimentary succession recovered in 1975 from the Black Sea (DSDP 42B, Hole 380A). The carbon and hydrogen isotopic composition of n-alkanes as well as alkenones and palynology indicate large environmental changes in the Black Sea and/or in the sources of the water entering the Black Sea during the late Miocene. The hydrogen isotopes of alkenones, showing an enrichment of more than 80 ‰ at the end of the Miocene, imply a major shift in basin hydrology, possibly resulting in severely increased salinity. These changes in hydrogen isotopic composition of the alkenones concur both with sharp shifts in reconstructed sea surface temperature and palynological assemblages. Two intervals with negative water budget were identified, most likely caused by enhanced evaporation. The older and longer dry/evaporative phase predates the Maeotian/Pontian boundary (regional stages) at ~6.1 Ma. The younger negative water budget phase is partly coeval to the Messinian salinity crisis of Mediterranean. Both shifts to highly evaporative conditions are recorded in both Taman Peninsula (Russia) and DSDP 42B 380A locations. These recurrent dryer phases were, most likely, the result of important hydrological changes over a significantly larger area around the Black Sea area during the upper Miocene.

  19. Mid-Pliocene Planktic Foraminifer Census Data and Alkenone Unsaturation Indices from Ocean Drilling Program Hole 677A

    USGS Publications Warehouse

    Robinson, Marci; Caballero, Rocio; Pohlman, Emily; Herbert, Timothy; Peck, Victoria; Dowsett, Harry

    2008-01-01

    The U.S. Geological Survey is conducting a long-term study of mid-Pliocene climatic and oceanographic conditions. One of the key elements of the study involves the use of quantitative composition of planktic foraminifer assemblages in conjunction with other proxies to constrain estimates of sea-surface temperature (SST) and to identify major oceanographic boundaries and water masses. Raw census data are made available as soon as possible after analysis through a series of reports that provide the basic data for future work. In this report we present raw census data (table 1) for planktic foraminifer assemblages in 14 samples from Ocean Drilling Program (ODP) Hole 677A. We also present alkenone unsaturation index (UK'37) analyses for 89 samples from ODP Hole 677A (table 2). ODP Hole 677A is located in the Panama basin, due west of Ecuador at 1?12.138'N., 83?44.220'W., in 3461.2 meters of water (fig. 1). A variety of statistical methods have been developed to transform foraminiferal census data in Pliocene sequences into quantitative estimates of Pliocene SST. Details of statistical techniques, taxonomic groupings, and oceanographic interpretations are presented in more formal publications (Dowsett and Poore, 1990, 1991; Dowsett, 1991, 2007a,b; Dowsett and Robinson, 1998, 2007; Dowsett and others, 1996, 1999).

  20. Atlantic core-top calibration of the U{sup K}{sub 37} index as a sea-surface palaeotemperature indicator

    SciTech Connect

    Rosell-Mele, A.; Eglinton, G.; Pflaumann, U.

    1995-08-01

    A field calibration of the U{sup K}{sub 37} index with sea surface temperature is discussed, through analysis of an extensive suite of surface sediments (n = 109) from the northeastern Atlantic (2{degrees}S-75{degrees}N). Values of U{sup K}{sub 37} are compared with sea surface temperatures for overlying waters measured at different depths and seasons, to obtain a correlation suitable for paleotemperature reconstructions. The best fit is obtained using surface (0 m) temperatures corresponding to caloric winter and autumn months. However, the annual average, spring and summer surface temperature equations also have high correlation coefficients, and are also appropriate for climatic studies. The results further validate the general applicability of the U{sup K}{sub 37} as a climatic proxy, because the climatic proxy, because the calibration equations are valid over a wide range of surface water temperatures (0-28{degrees}C) for different algal populations and are representative of the average contribution of alkenones to sediments, as found in sediment cores.

  1. Temperature calibration of lacustrine alkenones using in-situ sampling and growth cultures

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Toney, J. L.; Andersen, R.; Fritz, S. C.; Baker, P. A.; Grimm, E. C.; Theroux, S.; Amaral Zettler, L.; Nyren, P. E.

    2010-12-01

    Sedimentary alkenones have been found in an increasing number of lakes around the globe. Studies using molecular biological tools, however, indicate that haptophyte species that produce lacustrine alkenones differ from the oceanic species. In order to convert alkenone unsaturation ratios measured in sediments into temperature, it is necessary to obtain an accurate calibration for individual lakes. Using Lake George, North Dakota, U.S. as an example, we have carried out temperature calibrations by both in-situ water column sampling and culture growth experiments. In-situ measured lake water temperatures in the lake show a strong correlation with the alkenone unsaturation indices (r-squared = 0.82), indicating a rapid equilibrium of alkenone distributions with the lake water temperature in the water column. We applied the in-situ calibration to down-core measurements for Lake George and generated realistic temperature estimates for the past 8 kyr. Algal isolation and culture growth, on the other hand, reveal the presence of two different types of alkenone producing haptophytes. The species making a predominant C37:4 alkenone (species A) produced much greater concentrations of alkenones per unit volume than the species that produced a predominant C37:3 alkenone (species B). It is the first time that a haptophyte species (species A) making a predominant C37:4 alkenone is cultured successfully and now replicated at four different growth temperatures. The distribution of alkeones in Lake George sediments matches extremely well with the alkenones produced by species A, indicating species A is likely the producer for the alkenones in the sediments. The alkenone unsaturation ratio of alkenones produced by species A haptophyte shows a primary dependence on growth temperature as expected, but the slope of change appears to vary depending on the growth stages. The implications of our findings for paleoclimate reconstructions using lacustrine alkenones will be discussed.

  2. Climate and sea ice variability in the SW Labrador Sea during the late Holocene

    NASA Astrophysics Data System (ADS)

    Weckström, Kaarina; Massé, Guillaume; Collins, Lewis; Sicre, Marie-Alexandrine; Bouloubassi, Ioanna; Seidenkrantz, Marit-Solveig; Olsen, Jesper; Kuijpers, Antoon

    2014-05-01

    The recent rapid decline in Arctic sea ice cover has increased the need to improve the accuracy of the sea ice components in climate models and to provide detailed long-term sea ice records based on proxy data. Recently, the highly branched isoprenoid IP25 has emerged as a potential sea ice specific proxy for past sea ice cover, found in marine sediments underlying seasonal sea ice. We tested the reliability of this biomarker against observational sea ice data off Newfoundland (SW Labrador Sea), where box cores covering the last ca. 100-150 years were collected. Based on the results, IP25 proved to be a robust and reliable proxy for reconstructing variability in past sea ice concentrations in the area. After having successfully validated the proxy in the SW Labrador Sea, we further analysed IP25 from a sediment core NE of Newfoundland covering the last ca. 5000 years, providing the southernmost multi-millennial record of this proxy to date. Based on this record and on diatom and dinoflagellate cyst data and alkenone-based sea surface temperatures (SSTs) from the same core, we reconstructed climatic conditions in and Arctic sea ice export to the SW Labrador Sea area: Alkenone-based SSTs show a clear albeit variable decline after the Holocene Climate Optimum, while at the same time diatom and dinoflagellate cyst data suggest decreased melt water export from the Arctic. The IP25 record reveals increased sea ice export from the Baffin and Hudson Bays starting ca 1500 yr cal. BP, accelerating ca. 800 yr cal. BP and culminating at the height of the Little Ice Age. Sea ice export during the last century is comparable to the export during the Medieval Climate Anomaly.

  3. Spatial and temporal characteristics of the phytoplankton biomarkers in the surface water in South China Sea

    NASA Astrophysics Data System (ADS)

    Li, L.; Liu, J.; Wang, H.; Dong, L.; He, J.

    2011-12-01

    Organic biomarkers were used to investigate the modern distribution of the phytoplanktons in the South China Sea: Brassicasterol, Dinosterol, C37-Alkenone, and 1,15-C30 alkyl-Diol, which correspond to diatoms, dinoflagellates, coccolithophores, and yellow green algae, respectively. The distribution for the phytoplankton biomarks exhibit typical spatial and temporal characteristic: in summer, high biomass was found in the Pearl River Estuary and east of Hainan Island, while in spring, besides Pearl River Estuary, higher biomass was found also in Luzon strait and western Luzon Island. The decreasing tendency for the offshore sites and deep basin sites was exhibited in both seasons. The results indicated that the distribution of phytoplankton biomarkers in surface water of SCS is impacted and constrained by the hydrology condition and nutrients supply. Seasonal upwelling caused by the seasonal reversal eastern Asian monsoon in the SCS and continental riverine supply is the dominant reason for the nutrient supply, which resulted the typical features of regional distribution and seasonal variation. The community structure revealed by the lipids biomarkers indicated that diatom is the dominant species of phytoplankton in the studied area, and exhibit a decreasing trend form the near shore to the deep basin, while coccoliphore show a reverse feature with high value in the deep basin and Luzon strait, illustrating the different nutrient requirement by different marine organisms. The similar distribution of the alga and the corresponding biomarkers enhanced the feasibility of biomarker lipids in reconstructing the phytoplanktons community structure, which can be used in both the modern and past ecology study to improve our knowledge in the relationship between the marine ecology with the climate and environment change.

  4. Air-sea fluxes and surface layer turbulence around a sea surface temperature front

    NASA Technical Reports Server (NTRS)

    Friehe, C. A.; Shaw, W. J.; Davidson, K. L.; Rogers, D. P.; Large, W. G.; Stage, S. A.; Crescenti, G. H.; Khalsa, S. J. S.; Greenhut, G. K.; Li, F.

    1991-01-01

    The observed effects of sharp changes in sea surface temperature (SST) on the air-sea fluxes, surface roughness, and the turbulence structure in the surface layer and the marine atmospheric boundary layer are discussed. In situ flux and turbulence observations were carried out from three aircraft and two ships within the FASINEX framework. Three other aircraft used remote sensors to measure waves, microwave backscatter, and lidar signatures of cloud tops. Descriptions of the techniques, intercomparison of aircraft and ship flux data, and use of different methods for analyzing the fluxes from the aircraft data are described. Changing synoptic weather on three successive days yielded cases of wind direction both approximately parallel and perpendicular to a surface temperature front. For the wind perpendicular to the front, wind over both cold-to-warm and warm-to-cold surface temperatures occurred. Model results consistent with the observations suggest that an internal boundary layer forms at the SST.

  5. Plastics on the Sargasso sea surface.

    PubMed

    Carpenter, E J; Smith, K L

    1972-03-17

    Plastic particles, in concentrations averaging 3500 pieces and 290 grams per square kilometer, are widespread in the western Sargasso Sea. Pieces are brittle, apparently due to the weathering of the plasticizers, and many are in a pellet shape about 0.25 to 0.5 centimeters in diameter. The particles are surfaces for the attachment of diatoms and hydroids. Increasing production of plastics, combined with present waste-disposal practices, will undoubtedly lead to increases in the concentration of these particles. Plastics could be a source of some of the polychlorinated biphenyls recently observed in oceanic organisms.

  6. A global monthly sea surface temperature climatology

    SciTech Connect

    Shea, D.J.; Trenberth, K.E.; Reynolds, R.W. NOAA, Climate Analysis Center, Washington, DC )

    1992-09-01

    The paper presents a new global 2 deg x 2 deg monthly sea surface temperature (SST) climatology, referred here to as the Shea-Trenberth-Reynolds (STR) climatology, which was derived by modifying a 1950-1979-based SST climatology from the Climate Analysis Center (CAC), by using data from the Comprehensive Ocean-Atmosphere Data Set to improve the SST estimates in the regions of the Kuroshio and the Gulf Stream. A comparison of the STR climatology with the Alexander and Mobley SST climatology showed that the STR climatology is warmer in the Northern Hemisphere, and colder poleward of 45 deg S. 22 refs.

  7. Sea Surface Temperature and Vegetation Index

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is a composite MODIS image showing the 'green wave' of spring in North America and sea surface temperature in the ocean, collected over an 8-day period during the first week in April 2000. On land, the darker green pixels show where the most green foliage is being produced due to photosynthetic activity. Yellows on land show where there is little or no productivity and red is a boundary zone. In the ocean, orange and yellows show warmer waters and blues show colder values.

  8. Sea Surface Temperature from EUMETSAT Including Sentinel-3 SLSTR

    NASA Astrophysics Data System (ADS)

    O'Carroll, Anne; Bonekamp, Hans; Montagner, Francois; Santacesaria, Vincenzo; Tomazic, Igor

    2015-12-01

    The paper gives an overview of sea surface temperature (SST) activities at EUMETSAT including information on SST planned from the Sea and Land Surface Temperature Radiometer (SLSTR). Operational oceanography activities within the Marine Applications group at EUMETSAT continue with a focus on SST, sea surface winds, sea-ice products, radiative fluxes, significant wave height and sea surface topography. These are achieved through the mandatory, optional and third-party programmes, and for some products with the EUMETSAT Ocean and Sea-Ice Satellite Application Facility (OSI SAF). Progress towards products from sea-ice surface temperature, ocean colour products, turbidity and aerosol optical depth over water continue. Information on oceanography products from EUMETSAT can be found through the product navigator (http://navigator.eumetsat.int). EUMETSAT have been collaborating with ESA for a number of years on the development of SST for SLSTR.

  9. Sea surface temperature variability in the Colombian Basin, Caribbean Sea

    NASA Astrophysics Data System (ADS)

    Ruiz-Ochoa, Mauricio; Beier, Emilio; Bernal, Gladys; Barton, Eric Desmond

    2012-06-01

    Daily sea surface temperature (SST) data from the Advanced Very High Resolution Radiometer (AVHRR) database with ∼4 km of spatial resolution were analyzed for the period 1985-2009 in the Colombian Basin using harmonic and empirical orthogonal function (EOF) analysis. The data were compared with observational records in the Rosario Island National Park at 10 m depth (T10) from March 2003 to August 2005. SST values were higher than T10 from June to October (rainy season), but similar from December to February (dry season); both data sets have similar coefficient of variation. The mean SST distribution varies spatially, with minimum SST values in the coastal zone of La Guajira Peninsula and maximum values in the Darien and Mosquitos Gulfs. The seasonal variability explains up to 75% of the total variability in La Guajira, a high value compared with 40% in the Mosquitos Gulf. The most important feature of the splitting of SST variation into annual and semiannual harmonics in La Guajira is the relationship between their amplitudes. These are of the same order, which is not common in other ocean zones, where the semiannual component is only a small fraction of the annual dominated by the solar warming. The river water discharge, highest from August to November, produces low density surface water, reduces vertical mixing and limits the absorption of solar radiation to a thin surface layer, explaining the discrepancy between SST and T10 in the rainy season. The decomposition of the SST in EOFs indicated that the dominant mode of the basin is a uniform interannual variation in phase with the North Tropical Atlantic Index. The second mode, representing the variability of the Guajira upwelling, covaried strongly with the second mode of wind stress curl. The third mode reflected the role of the vertical atmospheric circulation cell associated with the Caribbean Low Level Jet off Central America.

  10. Modern average global sea-surface temperature

    USGS Publications Warehouse

    Schweitzer, Peter N.

    1993-01-01

    The data contained in this data set are derived from the NOAA Advanced Very High Resolution Radiometer Multichannel Sea Surface Temperature data (AVHRR MCSST), which are obtainable from the Distributed Active Archive Center at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. The JPL tapes contain weekly images of SST from October 1981 through December 1990 in nine regions of the world ocean: North Atlantic, Eastern North Atlantic, South Atlantic, Agulhas, Indian, Southeast Pacific, Southwest Pacific, Northeast Pacific, and Northwest Pacific. This data set represents the results of calculations carried out on the NOAA data and also contains the source code of the programs that made the calculations. The objective was to derive the average sea-surface temperature of each month and week throughout the whole 10-year series, meaning, for example, that data from January of each year would be averaged together. The result is 12 monthly and 52 weekly images for each of the oceanic regions. Averaging the images in this way tends to reduce the number of grid cells that lack valid data and to suppress interannual variability.

  11. Sea surface wind stress in stratified atmospheric flow

    SciTech Connect

    Myrhaug, D.; Slaattelid, O.H.

    1996-12-31

    The paper presents the wind shear stress on the sea surface as well as the velocity profile in stably stratified atmospheric boundary layer flow over wind waves by using similarity theory. For a given geostrophic velocity, Coriolis parameter, spectral peak period and stratification parameter the sea surface shear stress is determined. Further, the direction of the sea surface shear stress and the velocity profile are given. Parameterizations of the results are also presented. Finally, the engineering relevance of the results is discussed.

  12. Estimating the Ocean Flow Field From Combined Sea Surface Temperature and Sea Surface Height Data

    NASA Technical Reports Server (NTRS)

    Stammer, Detlef

    2000-01-01

    The primary focus of this project was on the estimation of the three-dimensional, absolute and time-evolving general circulation of the global ocean from a combined analysis of remotely sensed fields of sea surface temperature (SST) and sea surface height (SSH). The synthesis of those two fields was performed with other relevant physical data, and appropriate dynamical ocean models with emphasis on constraining ocean general circulation models by a combination of both SST and SSH data. This effort is directly related to an attempt to describe the mechanisms which give rise to observed SST and its variability on seasonal and inter-annual timescales, its relation to ocean-atmosphere interaction, and the dynamical coupling between the ocean mixed layer and the deep interior ocean. This is one of the fundamental climate related questions being pursued currently under the CLIVAR Program. Because of the strong turbulent mixing associated with atmospheric fluxes of momentum, heat and freshwater through the sea surface, the ocean forms a shallow surface boundary layer, the mixed layer which is largely homogeneous in its constituents. The relation between the temperature of the remotely sensed "skin" and the bulk of the mixed layer is largely understood (Reynolds and Smith 1994; Emery et al., 1995). However, because the surface mixed layer is effectively decoupled from the underlying ocean dynamics, an interpretation of satellite SST observations in isolation and in direct use for dynamical studies is very difficult. As a result, the impact of SST data on the understanding of ocean variability.

  13. Satellite Sensed Skin Sea Surface Temperature

    NASA Technical Reports Server (NTRS)

    Donlon, Craig

    1997-01-01

    Quantitative predictions of spatial and temporal changes the global climate rely heavily on the use of computer models. Unfortunately, such models cannot provide the basis for climate prediction because key physical processes are inadequately treated. Consequently, fine tuning procedures are often used to optimize the fit between model output and observational data and the validation of climate models using observations is essential if model based predictions of climate change are to be treated with any degree of confidence. Satellite Sea Surface Temperature (SST) observations provide high spatial and temporal resolution data which is extremely well suited to the initialization, definition of boundary conditions and, validation of climate models. In the case of coupled ocean-atmosphere models, the SST (or more correctly the 'Skin' SST (SSST)) is a fundamental diagnostic variable to consider in the validation process. Daily global SST maps derived from satellite sensors also provide adequate data for the detection of global patterns of change which, unlike any other SST data set, repeatedly extend into the southern hemisphere extra-tropical regions. Such data are essential to the success of the spatial 'fingerprint' technique, which seeks to establish a north-south asymmetry where warming is suppressed in the high latitude Southern Ocean. Some estimates suggest that there is a greater than 80% chance of directly detecting significant change (97.5 % confidence level) after 10-12 years of consistent global observations of mean sea surface temperature. However, these latter statements should be qualified with the assumption that a negligible drift in the observing system exists and that biases between individual instruments required to derive a long term data set are small. Given that current estimates for the magnitude of global warming of 0.015 K yr(sup -1) - 0.025 K yr(sup -1), satellite SST data sets need to be both accurate and stable if such a warming trend is to

  14. Sea surface temperatures from VAS MSI data

    NASA Technical Reports Server (NTRS)

    Bates, J. J.

    1984-01-01

    A procedure is developed for estimating sea surface temperatures from multispectral image data acquired from the VISSR atmospheric sounder on the geostationary GOES satellites. Theoretical regression equations for two and three infrared window channels are empirically tuned using clear field of view satellite radiances matched with reports of SST from NOAA fixed environmental buoys. The empirical regression equations are then used to produce daily regional analyses of SST. Monthly mean SST's for the western North Atlantic and the eastern equatorial Pacific during March and July 1982 were produced for use in the SST Intercomparison Workshop Series. Workshop results showed VAS SST's have a scatter of 0.8-1.0 C and a slight warm bias with respect to the other measurements of SST. The VAS SST's show no discernible bias in the region of El Chichon volcanic aerosol cloud.

  15. Middle Pliocene sea surface temperature variability

    USGS Publications Warehouse

    Dowsett, H.J.; Chandler, M.A.; Cronin, T. M.; Dwyer, G.S.

    2005-01-01

    Estimates of sea surface temperature (SST) based upon foraminifer, diatom, and ostracod assemblages from ocean cores reveal a warm phase of the Pliocene between about 3.3 and 3.0 Ma. Pollen records and plant megafossils, although not as well dated, show evidence for a warmer climate at about the same time. Increased greenhouse forcing and altered ocean heat transport are the leading candidates for the underlying cause of Pliocene global warmth. Despite being a period of global warmth, this interval encompasses considerable variability. Two new SST reconstructions are presented that are designed to provide a climatological error bar for warm peak phases of the Pliocene and to document the spatial distribution and magnitude of SST variability within the mid-Pliocene warm period. These data suggest long-term stability of low-latitude SST and document greater variability in regions of maximum warming. Copyright 2005 by the American Geophysical Union.

  16. Surface current observatons--Beaufort Sea, 1972

    USGS Publications Warehouse

    Barnes, Peter; Garlow, Richard

    1975-01-01

    Sediment transport via water and ice in the Beaufort Sea off northern Alaska is related to the movement of the surficial waters. As development proceeds along the north slope of alaska, a knowledge of the potential drift trajectories of water, ice, sediment and pollutants will be needed. In an attempt to better define the probable paths and rates of transport, 4200 surface drift cards were dropped during the U.S. Coast Guard WEBSEC cruise of August and September, 1972. The results of this release are the subject of this report. Because the data presented here will be used primarily by those interested in solving problems of transport, the emphasis has been placed on data presentation rather than a detailed analysis of the circulation. (Sinha-OEIS)

  17. Sea surface temperature: Observations from geostationary satellites

    NASA Astrophysics Data System (ADS)

    Bates, John J.; Smith, William L.

    1985-11-01

    A procedure is developed for estimating sea surface temperatures (SST) from multispectral image data acquired from the VISSR atmospheric sounder (VAS) on the geostationary GOES satellites. Theoretical regression equations for two and three infrared window channels are empirically tuned by using clear field of view satellite radiances matched with reports of SST from NOAA fixed environmental buoys from 1982. The empirical regression equations are then used to produce daily regional analyses of SST. The daily analyses are used to study the response of SST's to the passage of Hurricane Alicia (1983) and Hurricane Debbie (1982) and are also used as a first guess surface temperature in the retrieval of atmospheric temperature and moisture profiles over the oceanic regions. Monthly mean SST's for the western North Atlantic and the eastern equatorial Pacific during March and July 1982 were produced for use in the NASA/JPL SST intercomparison workshop series. Workshop results showed VAS SST's have a scatter of 0.8°-1.0°C and a slight warm bias with respect to the other measurements of SST. Subsequently, a second set of VAS/ buoy matches collected during 1983 and 1984 was used to produce a set of bias corrected regression relations for VAS.

  18. A multispectral method of determining sea surface temperatures

    NASA Technical Reports Server (NTRS)

    Shenk, W. E.

    1972-01-01

    A multispectral method for determining sea surface temperatures is discussed. The specifications of the equipment and the atmospheric conditions required for successful multispectral data acquisition are described. Examples of data obtained in the North Atlantic Ocean are presented. The differences between the actual sea surface temperatures and the equivalent blackbody temperatures as determined by a radiometer are plotted.

  19. Correlations between altimetric sea surface height and radiometric sea surface temperature in the South Atlantic

    NASA Astrophysics Data System (ADS)

    Jones, Matthew S.; Allen, Myles; Guymer, Trevor; Saunders, Mark

    1998-04-01

    In the last decade, satellite altimetric measurements of sea surface height (SSH) and infrared radiometric measurements of sea surface temperature (SST) have provided a wealth of information about ocean circulation and atmosphere-ocean interactions. SSH is a depth-integrated quantity dependent upon the temperature and salinity structure of the water column and on the depth independent barotropic contribution. SST from infrared radiometers is a surface parameter representing the temperature of the top few microns of the ocean surface. Hence any relationship between SST and SSH provides dynamical information about the coupling between the ocean surface and subsurface. It also offers a promise of new techniques such as interpolating SSH data using SST and of improved calculations of eddy kinetic energy. We use SST data from the along-track scanning radiometer on ERS-I and SSH data from the TOPEX/POSEIDON instrument to examine the relationship between SST and SSH anomalies within the South Atlantic region for 1993 and 1994. We find that positive (≈0.2-0.6) spatial cross correlations between SST and SSH anomalies at zero lag are present throughout the region at large scales (wavelengths >1000 km). Small-scale correlations, however, are high (≈0.7) only in areas associated with fronts and mesoscale variability. These small-scale correlations are seasonal, being strongest in winter and weakest in summer. We discuss the application of these correlations to various techniques requiring the synergistic use of SSH and SST data.

  20. Estimating the Ocean Flow Field from Combined Sea Surface Temperature and Sea Surface Height Data

    NASA Technical Reports Server (NTRS)

    Stammer, Detlef; Lindstrom, Eric (Technical Monitor)

    2002-01-01

    This project was part of a previous grant at MIT that was moved over to the Scripps Institution of Oceanography (SIO) together with the principal investigator. The final report provided here is concerned only with the work performed at SIO since January 2000. The primary focus of this project was the study of the three-dimensional, absolute and time-evolving general circulation of the global ocean from a combined analysis of remotely sensed fields of sea surface temperature (SST) and sea surface height (SSH). The synthesis of those two fields was performed with other relevant physical data, and appropriate dynamical ocean models with emphasis on constraining ocean general circulation models by a combination of both SST and SSH data. The central goal of the project was to improve our understanding and modeling of the relationship between the SST and its variability to internal ocean dynamics, and the overlying atmosphere, and to explore the relative roles of air-sea fluxes and internal ocean dynamics in establishing anomalies in SST on annual and longer time scales. An understanding of those problems will feed into the general discussion on how SST anomalies vary with time and the extend to which they interact with the atmosphere.

  1. Synchronous tropical South China Sea SST change and Greenland warming during deglaciation.

    PubMed

    Kienast, M; Steinke, S; Stattegger, K; Calvert, S E

    2001-03-16

    The tropical ocean plays a major role in global climate. It is therefore crucial to establish the precise phase between tropical and high-latitude climate variability during past abrupt climate events in order to gain insight into the mechanisms of global climate change. Here we present alkenone sea surface temperature (SST) records from the tropical South China Sea that show an abrupt temperature increase of at least 1 degrees C at the end of the last glacial period. Within the recognized dating uncertainties, this SST increase is synchronous with the Bølling warming observed at 14.6 thousand years ago in the Greenland Ice Sheet Project 2 ice core.

  2. Regional and global significance of Pliocene sea surface temperatures from the Gulf of Cadiz (Site U1387) and the Mediterranean

    NASA Astrophysics Data System (ADS)

    Tzanova, Alexandrina; Herbert, Timothy D.

    2015-10-01

    The Atlantic-Mediterranean water exchange is a component of global ocean circulation capable of influencing deep water formation in the North Atlantic, yet it is poorly constrained for the time period preceding the intensification of Northern Hemisphere Glaciation (NHG). The sea surface temperature (SST) gradient between the Atlantic and Mediterranean sides of the Strait of Gibraltar can shed light on the communication between the two basins. IODP Site U1387 in the Gulf of Cadiz provides the first alkenone based reconstruction of SST for the Atlantic waters that flowed into the Mediterranean Sea during the Pliocene. This site reflects open ocean North Atlantic subtropical temperature trends while the published SST records from the Rossello composite section (Sicily) in the Mediterranean reflect the addition of regional, continentally-influenced signals from Europe and Northern Africa. The Mediterranean, in particular, may be influenced by high latitude Northern hemisphere climatic evolution. In the modern regime the sites discussed in this work have comparable SST and uninhibited surface connection; however, change in local heat loss/gain over the Mediterranean due to variability in latent heat loss and obstructed connection can result in a gradient between the sites in the Pliocene. The Pliocene surface waters of the Gulf of Cadiz and the Mediterranean Sea were as much as 7 °C warmer than the modern average of ~ 19-20 °C. The reconstructed temperatures show a ~ 1 °C cooling for the Atlantic side of the Strait of Gibraltar from ~ 6 Ma to ~ 2.7 Ma and increasingly cooler glacials. The long-term SST record from Site U1387 provides a basis for future studies into the hydrological balance of the Mediterranean and the temperature component of Mediterranean Outflow Water (MOW) density. We compared SST on either side of Gibraltar between ~ 3.4-2.7 Ma and found that between ~ 2.7 and ~ 3.1 Ma the Mediterranean and Atlantic surface waters show comparable average

  3. 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.

  4. Zanclean/Piacenzian transition on Cyprus (SE Mediterranean): calcareous nannofossil and Sea Surface Temperatures evidence of sapropel formation

    NASA Astrophysics Data System (ADS)

    Athanasiou, Maria; Triantaphyllou, Maria; Bouloubassi, Ioanna; Dimiza, Margarita; Gogou, Alexandra; Klein, Vincent; Parinos, Constantine; Theodoroyu, George

    2016-04-01

    Quantitative analyses of calcareous nannofossils in the sediments of Pissouri South section on the island of Cyprus have produced a paleoceanographic record reflecting the paleoclimatic conditions during Zanclean/Piacenzian transition. According to the performed calcareous nannofossil biostratigraphy the studied section is correlated with MNN14/15 and MNN16 calcareous nannofossil biozones and is astronomically dated between 4.065 and 3.217 Ma. Intervals of increased organic carbon content along with the positive values of Florisphaera profunda, Helicosphaera sellii, Discoaster spp. and the subsequent increase of stratification S-index correspond to the sapropel deposition during periods of wetter climate and intense continental runoff especially from the river Nile. These layers are alternating with grey marly intervals, featured by the increased values of small placoliths of Reticulofenestra and Gephyrocapsa species, which are indicative of eutrophic conditions during intense surface waters mixing. Pissouri South section comprises a SSTs sequence using alkenone unsaturation index (Uk 37) providing with the first continuous record from SE Mediterranean covering the Zanclean/Piacenzian (Pliocene) transition (~ 4.1-3.2 Ma). Correlation of the total alkenone concentration to the calcareous nannofossil assemblage and especially representatives among Noelaerhabdaceae family revealed that Pseudoemiliania lacunosa probably had similar temperature sensitivity to that of Emiliania huxleyi, currently producing alkenones in present day oceans.Our data support the prevalence of a generally warm phase characterized by the absence of high-frequency climate variations in the southeastern Mediterranean during the Zanclean/Piacenzian (Early/Late Pliocene) transition.

  5. Sea-ice and surface water circulation, Alaskan continental shelf

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    The author has identified the following significant results. Over 1500 water samples from surface and from standard hydrographic depths were collected during June and July 1973 from Bering Sea and Gulf of Alaska. The measurement of temperature, salinity, and productivity indicated that various distinct water masses cover the Bering Sea Shelf. The suspended load in surface waters will be correlated with the ERTS-1 imagery as it becomes available to delineate the surface water circulation. The movement of ice floes in the Bering Strait and Bering Sea indicated that movement of ice varies considerably and may depend on wind stress as well as ocean currents.

  6. 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.

  7. The use of alkenone δ 13C as a paleo-growth rate proxy

    NASA Astrophysics Data System (ADS)

    Pagani, M.; Hall, J.

    2003-12-01

    The carbon isotopic fractionation that occurs during marine photosynthetic carbon fixation (ɛ p) is primarily a function of the concentration of CO2aq, cellular growth rate, and cell geometry. Field data from natural haptophyte populations provide evidence for a robust relationship between the ɛ p values derived from diunsaturated alkenones (ɛ p37:2) and the concentration of reactive soluble phosphate. Given our understanding of the factors controlling ɛ p37:2, it is likely that differences in algal growth rates are responsible for this relationship. Records of ɛ p reconstructed from the stable carbon isotopic of diunsaturated alkenones and coeval planktonic foraminifera have been used to reconstruct the long-term evolution of atmospheric carbon dioxide during the Neogene by restricting analysis to relatively stable oceanographic environments and thus minimizing the effects of variable nutrient availability and cellular growth rates. However, ɛ p37:2 trends from different ocean sites do not only reflect global pCO2 levels, because there are significant differences in isotopic trends between basins. These differences likely reflect regional differences in haptophyte growth rates. For example, records of ɛ p37:2 from site 516 in the southwest Atlantic records a large, and permanent decrease in ɛ p37:2 between 20.3 to 19.5 Ma, coincident with a ~4 degree decline in surface water temperature inferred from the δ 18O of planktonic foraminifera. This decrease in ɛ p37:2 is interpreted as reflecting both higher growth rates and nutrient concentrations in the upper-water column, caused by a reduction in upper water column stratification. Disappearance of measurable alkenones by ~17 Ma occurs prior to a reduction in surface-to-thermocline Δ δ 18O and Δ δ 13C gradients, and is attributed to low nutrient concentrations and reduced influence of proto-Antarctic Intermediate Water. We continue to investigate a potential nutrient control on the character of ɛ p37

  8. Further evaluation of long-chain alkenones as indicators of paleoceanographic conditions

    NASA Astrophysics Data System (ADS)

    Prahl, Fredrick G.; Muehlhausen, Laurel A.; Zahnle, Debra L.

    1988-09-01

    Cultures of the marine coccolithophorid, Emiliania huxleyi, were grown in the laboratory at five temperatures (8°, 10°, 15°, 20°, 25°C) and monitored by capillary gas chromatography for their long-chain, unsaturated lipid compositions. The long-chain lipids of this plant comprise a series of C 37, C 38 and C 39 di-, tri- and, in cells grown below 15°C, tetra-unsaturated methyl and ethyl ketones and a methyl and ethyl ester of a di-unsaturated C 36 fatty acid. Systematic changes in the degree of unsaturation and in the overall carbon chain length distribution of the alkenones and in the proportion of fatty acid esters relative to alkenones are noted as a function of growth temperature. We present temperature calibrations for these changes in the lipid composition of laboratory cultures and compare these results with the compositions of this biomarker series measured in a variety of sediments accumulating beneath warm (⩾25°C) and cold (⩽12°C) surface waters in the tropical and temperate North Pacific Ocean, respectively. The comparisons demonstrate 1) this series of biomarkers is deposited in these oceanic sediments with minimal evidence of alteration to its original composition and 2) the strain of E. huxleyi used in this laboratory calibration is representative of the "average" marine phytoplankton supplying this novel series of biomarkers to contemporary sediments in these two environments and a wide variety of other oceanic environments. The long-chain alkenones constitute a major component (8.0 ± 2.9%) of the total organic carbon content of living cells of E. huxleyi. The high cellular abundance of these compounds appears to be relatively constant and independent of the growth temperature of the plant. These biomarkers provide a well-designed and useful geochemical tool for assessing variations not only in surface water temperatures but potentially also in the productivity of an important group of marine phytoplankton in oceans of the recent and

  9. Fouling-resistant surfaces of tropical sea stars.

    PubMed

    Guenther, Jana; Walker-Smith, Genefor; Warén, Anders; De Nys, Rocky

    2007-01-01

    Qualitative evidence suggests sea stars are free of fouling organisms; however the presence of fouling-resistant surfaces of sea stars has not previously been documented. Field surveys were conducted in northern Queensland, Australia, during the wet and dry seasons and several tropical sea star species were examined for surface-associated micro- and macro-organisms. Mean bacterial abundances on seven sea star species were approximately 10(4) to 10(5) cells cm(-2) during both seasons. There were no consistent trends in bacterial abundances with season, species and aboral positions on sea star arms. No common generalist fouling organisms, such as algae, barnacles, serpulid polychaetes, bryozoans and ascidians, were found on any specimens of 12 sea star species. However, low numbers of parasitic and commensal macro-organisms were found on six sea star species. The gastropods Parvioris fulvescens, Asterolamia hians, Thyca (Granulithyca) nardoafrianti and Thyca crystallina were found exclusively on the sea stars Archaster typicus, Astropecten indicus, Nardoa pauciforis and Linckia laevigata, respectively. The shrimp Periclimenes soror was only found on Acanthaster planci, and the polychaete Ophiodromus sp. on A. typicus. The copepods Stellicola illgi and Paramolgus sp. were only found on L. laevigata and Echinaster luzonicus, respectively. As no common generalist fouling organisms were discovered, sea stars offer an excellent model to investigate the mechanisms driving fouling-resistant surfaces and the selective settlement of specialist invertebrates.

  10. Assessment of Plio-Pleistocene Sea Surface Temperature Evolution Across Ocean Basins, Hemispheres, and Latitudes

    NASA Astrophysics Data System (ADS)

    Peterson, L.; Lawrence, K. T.; Mauriello, H.; Wilson, J.; Holte, L.

    2015-12-01

    New sea surface temperature (SST) records from the southern Pacific and southern Atlantic Oceans allow assessment of similarities and differences in climate evolution across ocean basins, hemispheres, and latitudes over the last 5 million years. Our high-resolution, alkenone-derived SST records from ODP Sites 1088 (South Atlantic, 41°S) and 1125 (South Pacific, 42°S) share strong structural similarities. When compared with SST records from the mid-latitudes of the northern hemisphere, these records provide compelling evidence for broadly hemispherically symmetrical open-ocean temperature evolution in both ocean basins as tropical warm pools contracted over the Plio-Pleistocene. This symmetry in temperature evolution occurs despite strong asymmetries in the development of the cryosphere over this interval, which was marked by extensive northern hemisphere ice sheet growth. Parallel SST evolution across ocean basins and hemispheres suggests that on longterm (>105 yr) timescales, many regions of the world ocean are more sensitive to the global energy budget than to local or regional climate dynamics, although important exceptions include coastal upwelling zone SSTs, high latitude SSTs, and benthic δ18O. Our analysis further reveals that throughout the last 5 Ma, temperature evolution in the extra-tropical Pacific of both hemispheres is very similar to the evolution of SST in the eastern equatorial Pacific upwelling zone, revealing tight coupling between the growth of meridional and equatorial Pacific zonal temperature gradients over this interval as both the extra-tropics and the eastern equatorial Pacific cold tongue underwent cooling. Finally, while long term temperature evolution is broadly consistent across latitudes and ocean basins throughout the entire Plio-Pleistocene, we see evidence that climate coupling on orbital timescales strengthened significantly at 2.7 Ma, at which point obliquity-band coherence emerges among diverse SST records. We attribute this

  11. The distribution of iodide at the sea surface.

    PubMed

    Chance, Rosie; Baker, Alex R; Carpenter, Lucy; Jickells, Tim D

    2014-08-01

    Recent studies have highlighted the impact of sea surface iodide concentrations on the deposition of ozone to the sea surface and the sea to air flux of reactive iodine. The use of models to predict this flux demands accurate, spatially distributed sea surface iodide concentrations, but to date, the observational data required to support this is sparse and mostly arises from independent studies conducted on small geographical and temporal scales. We have compiled the available measurements of sea surface iodide to produce a data set spanning latitudes from 69°S to 66°N, which reveals a coherent, large scale distribution pattern, with highest concentrations observed in tropical waters. Relationships between iodide concentration and more readily available parameters (chlorophyll, nitrate, sea surface temperature, salinity, mixed layer depth) are evaluated as tools to predict iodide concentration. Of the variables tested, sea surface temperature is the strongest predictor of iodide concentration. Nitrate was also strongly inversely associated with iodide concentration, but chlorophyll-a was not.

  12. Synthesis and analysis of an alkenone-free biodiesel from Isochrysis sp.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Some marine microalgae, such as Isochrysis sp., produce high-melting (~70 ºC) lipids known as long-chain alkenones that detrimentally affect biodiesel fuel quality. A method has been developed for the production of an alkenone-free Isochrysis biodiesel. This material was prepared on sufficient scale...

  13. Sea surface temperature of the coastal zones of France

    NASA Technical Reports Server (NTRS)

    Deschamps, P. Y.; Crepon, M.; Monget, J. M.; Verger, F. (Principal Investigator); Frouin, R.; Cassanet, J.; Wald, L.

    1980-01-01

    The various thermal gradients in the coastal zones of France were mapped with regard to natural phenomena and man made thermal effluents. The mesoscale thermal features of the English Channel, the Bay of Biscay, and the northwestern Mediterranean Sea were also studied. The evolution of the thermal gradients generated by the main estuaries of the French coastal zones was investigated along with the modeling of diurnal heating of the sea surface and its influence on the oceanic surface layers.

  14. Observation of Sea Ice Surface Thermal States Under Cloud Cover

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Perovich, D. K.; Gow, A. J.; Kwok, R.; Barber, D. G.; Comiso, J. C.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Clouds interfere with the distribution of short-wave and long-wave radiations over sea ice, and thereby strongly affect the surface energy balance in polar regions. To evaluate the overall effects of clouds on climatic feedback processes in the atmosphere-ice-ocean system, the challenge is to observe sea ice surface thermal states under both clear sky and cloudy conditions. From laboratory experiments, we show that C-band radar (transparent to clouds) backscatter is very sensitive to the surface temperature of first-year sea ice. The effect of sea ice surface temperature on the magnitude of backscatter change depends on the thermal regimes of sea ice thermodynamic states. For the temperature range above the mirabilite (Na2SO4.10H20) crystallization point (-8.2 C), C-band data show sea ice backscatter changes by 8-10 dB for incident angles from 20 to 35 deg at both horizontal and vertical polarizations. For temperatures below the mirabilite point but above the crystallization point of MgCl2.8H2O (-18.0 C), relatively strong backwater changes between 4-6 dB are observed. These backscatter changes correspond to approximately 8 C change in temperature for both cases. The backscattering mechanism is related to the temperature which determines the thermodynamic distribution of brine volume in the sea ice surface layer. The backscatter is positively correlated to temperature and the process is reversible with thermodynamic variations such as diurnal insolation effects. From two different dates in May 1993 with clear and overcast conditions determined by the Advanced Very High Resolution Radiometer (AVHRR), concurrent Earth Resources Satellite 1 (ERS-1) C-band ice observed with increases in backscatter over first-year sea ice, and verified by increases in in-situ sea ice surface temperatures measured at the Collaborative-Interdisciplinary Cryosphere Experiment (C-ICE) site.

  15. 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

  16. Hemispheric Symmetry of Mid-Latitude Sea Surface Conditions during Plio-Pleistocene Glaciation: Insights from the Southwest Pacific

    NASA Astrophysics Data System (ADS)

    Peterson, L.; Lawrence, K. T.; Kelly, C.; Schaupp, C. M.; Seidenstein, J.

    2012-12-01

    The hallmark of the global transition from the warm climate conditions of the Pliocene to the cooler conditions of the Pleistocene is the intensification of glaciation in the northern hemisphere, yet little is known about the (a)symmetry between the hemispheres in the evolution of the climate system during this key climate transition. In order to better assess hemispheric (a)symmetry across the Plio-Pleistocene, we present new records of sea surface temperature (SST), ocean productivity, and global ice volume for the late Pliocene and Pleistocene, which are based on stable isotope and alkenone analyses performed on marine sediments at Ocean Drilling Program (ODP) Site 1125 in the southwest Pacific (42°S, 178°W). Our data indicate that SSTs cooled ~4°C between the late Pliocene and late Pleistocene, a magnitude of cooling comparable to that observed at mid-latitude sites in both the South (Site 1090; 43°S) and North Atlantic (Site 607; 41°N). The magnitude, as well as the timing, of this cooling suggest a hemispherically symmetric contraction of the low latitude warm pool at the end of the early Pliocene warm period. In contrast, we observe a marked increase in orbital-scale temperature variability at Site 1125 during the late Pleistocene, a pattern that is not observed in other mid-latitude temperature records. On orbital timescales, we also observe significant precessional power in the Pliocene portion of southern hemisphere SST records, which is in contrast to the lack of precessional power in North Atlantic and tropical SST records. These hemispheric asymmetries suggest important differences in the climate system responses of the northern and southern hemispheres, and may provide clues regarding critical global climate system feedbacks.

  17. Progress in applying lacustrine alkenones as a quantitative continental paleotemperature proxy

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Longo, W. M.; Theroux, S.; Toney, J. L.; Dillon, J.; Zhao, J.; D'Andrea, W. J.; Hou, J.; Tarozo, R.; Amaral-Zettler, L. A.

    2013-12-01

    Alkenones are increasingly found in lakes around the world. Despite considerable success in using lake alkenones for continental paleotemperature reconstructions, there remain significant challenges. Unlike the well-known alkenone precursors in the open ocean, lacustrine alkenone-producing haptophytes are more genetically diverse; and many of the species remain uncultured. Lake sediments often contain complex alkenones and alkenoates that pose greater analytical challenges than marine samples. Here we present an overview (additional submissions to this session will detail certain aspects) of results from studying lakes around the world (including United States, western China, Greenland, northern Alaska, and Canada) over the past 8 years. The lakes investigated encompass a wide range in salinity (fresh to hypersaline) and temperature regime. Our major progress includes: 1) application of a new class of gas chromatographic stationary phase that provides unprecedented resolution of complex alkenone and alkenoate mixtures, preventing coleution of alkenones and alkenoates observed in conventional non-polar GC columns; 2) structural elucidation of a new 37:3 alkenone isomer in arctic lake sediments. The two 37:3 isomers coelute on conventional GC columns but are fully resolved using a vastly different class of GC stationary phase. Importantly, calibration of alkenone unsaturation to temperature differs between the C37:3 isomers; 3) development of a new HPLC stationary phase that efficiently separates alkenones by the degrees of unsaturation and double bond position, allowing high precision measurement of compound specific H isotopic ratios of alkenones; 4) application of DNA sequencing for identification of the specific alkenone-producing haptophyte species in lakes and assessment of seasonal successions of alkenone producing haptophytes; 5) successful enrichment of <3 μm-sized haptophytes that produces alkenones with a predominant 37:4 profile; 6) development of a new

  18. Sea surface signature of tropical cyclones using microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Kil, Bumjun; Burrage, Derek; Wesson, Joel; Howden, Stephan

    2013-06-01

    Measuring the sea surface during tropical cyclones (TC) is challenging due to severe weather conditions that prevent shipboard measurements and clouds which mask the sea surface for visible satellite sensors. However, sea surface emission in the microwave L-band can penetrate rain and clouds and be measured from space. The European Space Agency (ESA) MIRAS L-band radiometer on the Soil Moisture and Ocean Salinity (SMOS) satellite enables a view of the sea surface from which the effects of tropical cyclones on sea surface emissivity can be measured. The emissivity at these frequencies is a function of sea surface salinity (SSS), sea surface temperature (SST), sea surface roughness, polarization, and angle of emission. If the latter four variables can be estimated, then models of the sea surface emissivity can be used to invert SSS from measured brightness temperature (TB). Actual measured TB from space also has affects due to the ionosphere and troposphere, which have to be compensated for, and components due to the galactic and cosmic background radiation those have to be removed. In this research, we study the relationships between retrieved SSS from MIRAS, and SST and precipitation collected by the NASA TMI sensor from the Tropical Rainfall Measuring Mission (TRMM) satellite during Hurricane Isaac, in August 2012. During the slower movement of the storm, just before landfall on the vicinity of the Louisiana Shelf, higher precipitation amounts were associated with lower SSS and slightly increased SST. This increased trend of SST and lower SSS under regions of high precipitation are indicative of inhibited vertical mixing. The SMOS Level 2 SSS were filtered by a stepwise process with removal of high uncertainty in TB under conditions of strong surface roughness which are known to create noise. The signature of increased SST associated with increasing precipitation was associated with decreased SSS during the storm. Although further research is required, this study

  19. Ship-based measurements of sea surface topography

    NASA Astrophysics Data System (ADS)

    Foster, J. H.; Carter, G. S.; Merrifield, M. A.

    2009-06-01

    By equipping the research vessel Kilo Moana with a geodetic GPS receiver and a radar water level gauge, and using a kinematic GPS processing package, accurate 1 Hz estimates of the sea surface height were obtained. Geodetic positioning of ocean-platforms using only the GPS system cannot account for changes in the draft of the platform. This is especially problematic for ships, where changes in the load, speed and/or ocean density can change the ship's draft by 10s of centimeters. By installing a radar gauge this noise source can be removed from the estimates of the sea surface height. We envision that this technology could routinely provide high resolution information on the geoid, or the variation of the sea surface height, including sea-state, from an existing reference geoid.

  20. Modelling Sea Ice and Surface Wave Interactions in Polar Regions

    NASA Astrophysics Data System (ADS)

    Hosekova, L.; Aksenov, Y.; Coward, A.; Williams, T.; Bertino, L.; Nurser, A. J. G.

    2015-12-01

    In the Polar Oceans, the surface ocean waves break up sea ice cover and create the Marginal Ice Zone (MIZ), an area between the sea-ice free ocean and pack ice characterized by highly fragmented ice. This band of sea ice cover is undergoing dramatic changes due to sea ice retreat, with a widening of up to 39% in the Arctic Ocean reported over the last three decades and projections predicting a continuing increase. The surface waves, sea ice and ocean interact in the MIZ through multiple complex feedbacks and processes which are not accounted for in any of the present-day climate models. To address this issue, we present a model development which implements surface ocean wave effects in the global Ocean General Circulation Model (OGCM) NEMO, coupled to the CICE sea ice model. Our implementation takes into account a number of physical processes specific to the MIZ dynamics. Incoming surface waves are attenuated due to scattering and energy dissipation induced by the presence of ice cover, which is in turn fragmented in response to flexural stresses. This fragmentation modifies the floe size distribution and impacts the sea ice thermodynamics by increasing lateral melting and thus affecting momentum and heat transfer between sea ice and the upper ocean. In addition, the dynamics of the sea ice is modified by a combined rheology that takes into account floe collisions and allows for a more realistic representation of the MIZ. We present results from the NEMO OGCM at 1 and 0.25 degree resolution with a wave-ice interaction module. The module introduces two new diagnostics previously unavailable in OGCM's: surface wave spectra in sea ice covered areas, and floe size distribution (FSD) due to wave-induced fragmentation. We evaluate the sea ice and wave simulations with available observational estimates, and analyze the impact of these MIZ processes on the ocean and sea ice state. We focus on ocean mixing, stratification, circulation and the role of the MIZ in ocean

  1. Re-evaluating alkenone based CO2 estimates

    NASA Astrophysics Data System (ADS)

    Pagani, M.

    2013-05-01

    Multi-million year patterns of ocean temperatures and ice accumulation are relatively consistent with reconstructed CO2 records. Existing records allow for broad statements regarding climate sensitivity, but uncertainties in reconstructions can lead to considerable error. For example, alkenone-based CO2 reconstructions assume that diffusion of CO2aq is the dominant source of inorganic carbon for photosynthesis. However, the concentration of CO2aq is the lowest of all dissolved carbon species, constituting <1% of the total inorganic aqueous pool. This poses a problem for sustaining reasonable algal growth rates because the half saturation constant for the enzyme Rubisco, the primary carboxylase involved in algal photosythesis, is commonly higher than the average concentration of seawater CO2aq. That is, the concentration of CO2aq in the modern ocean is too low to maintain adequate reactions rates for Rubisco, and thus, algal growth. In order to maintain algal growth rates, most modern algae have strategies to increase intercellular CO2 concentrations. But, if such strategies were prevalent for alkenone-producing algae in the past, CO2 reconstructions could be compromised. This presentation will assess time periods when carbon-concentration strategies were potentially in play and consequences for existing CO2 records.

  2. The impact of land and sea surface variations on the Delaware sea breeze at local scales

    NASA Astrophysics Data System (ADS)

    Hughes, Christopher P.

    The summertime climate of coastal Delaware is greatly influenced by the intensity, frequency, and location of the local sea breeze circulation. Sea breeze induced changes in temperature, humidity, wind speed, and precipitation influence many aspects of Delaware's economy by affecting tourism, farming, air pollution density, energy usage, and the strength, and persistence of Delaware's wind resource. The sea breeze front can develop offshore or along the coastline and often creates a near surface thermal gradient in excess of 5°C. The purpose of this dissertation is to investigate the dynamics of the Delaware sea breeze with a focus on the immediate coastline using observed and modeled components, both at high resolutions (~200m). The Weather Research and Forecasting model (version 3.5) was employed over southern Delaware with 5 domains (4 levels of nesting), with resolutions ranging from 18km to 222m, for June 2013 to investigate the sensitivity of the sea breeze to land and sea surface variations. The land surface was modified in the model to improve the resolution, which led to the addition of land surface along the coastline and accounted for recent urban development. Nine-day composites of satellite sea surface temperatures were ingested into the model and an in-house SST forcing dataset was developed to account for spatial SST variation within the inland bays. Simulations, which include the modified land surface, introduce a distinct secondary atmospheric circulation across the coastline of Rehoboth Bay when synoptic offshore wind flow is weak. Model runs using high spatial- and temporal-resolution satellite sea surface temperatures over the ocean indicate that the sea breeze landfall time is sensitive to the SST when the circulation develops offshore. During the summer of 2013 a field campaign was conducted in the coastal locations of Rehoboth Beach, DE and Cape Henlopen, DE. At each location, a series of eleven small, autonomous thermo-sensors (i

  3. Simulated sea surface temperature and heat fluxes in different climates of the Baltic Sea.

    PubMed

    Döscher, Ralf; Meier, H E Markus

    2004-06-01

    The physical state of the Baltic Sea in possible future climates is approached by numerical model experiments with a regional coupled ocean-atmosphere model driven by different global simulations. Scenarios and recent climate simulations are compared to estimate changes. The sea surface is clearly warmer by 2.9 degrees C in the ensemble mean. The horizontal pattern of average annual mean warming can largely be explained in terms of ice-cover reduction. The transfer of heat from the atmosphere to the Baltic Sea shows a changed seasonal cycle: a reduced heat loss in fall, increased heat uptake in spring, and reduced heat uptake in summer. The interannual variability of surface temperature is generally increased. This is associated with a smoothed frequency distribution in northern basins. The overall heat budget shows increased solar radiation to the sea surface, which is balanced by changes of the other heat flux components.

  4. Simulated sea surface temperature and heat fluxes in different climates of the Baltic Sea.

    PubMed

    Döscher, Ralf; Meier, H E Markus

    2004-06-01

    The physical state of the Baltic Sea in possible future climates is approached by numerical model experiments with a regional coupled ocean-atmosphere model driven by different global simulations. Scenarios and recent climate simulations are compared to estimate changes. The sea surface is clearly warmer by 2.9 degrees C in the ensemble mean. The horizontal pattern of average annual mean warming can largely be explained in terms of ice-cover reduction. The transfer of heat from the atmosphere to the Baltic Sea shows a changed seasonal cycle: a reduced heat loss in fall, increased heat uptake in spring, and reduced heat uptake in summer. The interannual variability of surface temperature is generally increased. This is associated with a smoothed frequency distribution in northern basins. The overall heat budget shows increased solar radiation to the sea surface, which is balanced by changes of the other heat flux components. PMID:15264603

  5. Dynamics of a haptophyte bloom in Lake George, ND: Implications for alkenone-based temperature reconstructions

    NASA Astrophysics Data System (ADS)

    Theroux, S.; Toney, J. L.; Andersen, R.; Bohn, R.; Nyren, P.; Huang, Y.; Amaral-Zettler, L. A.

    2011-12-01

    Lacustrine alkenone records hold potential to be valuable sedimentary archives of continental paleotemperature. However, uncertainties in alkenone biosynthesis and bloom timing by novel species of lake-dwelling haptophytes hamper the widespread use of this proxy. Our previous research employing molecular ecology techniques on sediments and enrichment cultures revealed the presence of two distinct species of haptophyte in Lake George (LG), North Dakota (46.74°N, 99.49°W). LG sediments contain abundant tetra-unsaturated alkenones, typical of lake records, but it is unclear whether only one of the haptophyte species produces this alkenone signature. During the period from April-July 2011, we returned to Lake George to characterize the LG in situ water column bloom community. We performed bi-weekly sampling of the lake's photic zone to gauge the abundance of haptophyte species and their individual alkenone lipid profiles. Samples were collected at 0m, 5m and 10m depths and analyzed for bulk lipid signatures and DNA concentrations of the two haptophyte species. Group and species-specific Fluorescence In Situ Hybridization (FISH) probes targeting 18S rRNA determined the abundance of all haptophytes, as well as the novel Lake George haptophyte species (Species OTU8). We also used FISH probes to sort preserved cells from the environmental samples using flow-cytometry. This unique approach allows for the analysis of alkenone lipids from individual haptophyte communities. Using haptophytes isolated from environmental samples, our culture studies have yielded an unexpected diversity in LG haptophyte species and their alkenone production. Here we discuss alkenone concentration variability over the spring bloom period, the competition between multiple haptophyte species, and the implications of our findings on paleoclimate reconstructions using lacustrine alkenones.

  6. Cooling Mediterranean Sea surface temperatures during the Late Miocene provide a climate context for evolutionary transitions in Africa and Eurasia

    NASA Astrophysics Data System (ADS)

    Tzanova, Alexandrina; Herbert, Timothy D.; Peterson, Laura

    2015-06-01

    In the Late Miocene, grasslands proliferated, succulent plants diversified in the mid-latitudes, and the desert-like conditions appeared in the Sahara. Despite this major environmental change on land, the coeval deep-sea oxygen isotope record does not provide evidence for significant high latitude cooling or continental ice growth, making it difficult to relate widespread terrestrial environmental change to global climatic changes. A U37K‧ -derived sea surface temperature (SST) reconstruction spanning 13 to 6 Ma from uplifted hemipelagic sediments in Northern Italy provides the first continuous mid-latitude temperature record with which to compare the evolution of aridity and biotic events at similar latitudes in Northern Africa and Pakistan. Between 13 and 8.8 Ma, Mediterranean SST lay near the upper limit of the alkenone temperature proxy (∼28 °C), exceeding modern SST at the site by as much as 10 °C. Throughout the record, sapropel layers correspond to local SST maxima, suggesting that Late Miocene hydrological conditions in the Mediterranean responded to insolation forcing via mechanisms similar to those documented for the Plio-Pleistocene. Mediterranean SST cooled rapidly beginning at ∼8 Ma, with an episode of intense cooling to ∼19 °C between 7.2 Ma and 6.6 Ma, followed by a rebound to ∼25 °C preceding the Messinian Salinity Crisis at 5.9 Ma. These observations establish, for the first time, a direct relationship between increasing aridity in the Northern hemisphere mid-latitudes and significant cooling. Evidently, this cooling was not accompanied by significant growth in continental ice volume. The extreme warmth and subsequent cooling of the Mediterranean Sea are not well-represented in current Late Miocene climate models, which our results suggest underestimate regional warmth prior to the Late Miocene cooling. Evidence of secular cooling during the Late Miocene gives new support to the much-debated link between a possible decline in

  7. Radar Backscatter Across the Gulf Stream Sea Surface Temperature Front

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Li, F. K.; Walsh, E. J.; Lou, S. H.

    1998-01-01

    Ocean backscatter signatures were measured by the Jet Propulsion Laboratory airborne NUSCAT K(sub u)-band scatterometer across the Gulf Stream sea surface temperature front. The measurements were made during the Surface Wave Dynamics Experiment (SWADE) off the coast of Virginia and Maryland in the winter of 1991.

  8. Haptophyte DNA and alkenone signatures during a spring algal bloom event in Lake George, ND, USA

    NASA Astrophysics Data System (ADS)

    Theroux, S.; Huang, Y.; Amaral-Zettler, L.

    2012-12-01

    Lacustrine alkenone records have potential to be valuable sedimentary archives of continental paleotemperature. However, the use of the Uk37 paleotemperature proxy in lake environments is constrained by the genetic diversity of lake-dwelling, alkenone-producing haptophytes. Previous research in Lake George, ND revealed the presence of two alkenone-producing haptophyte species (Hap-A and Hap-B) whose individual contributions to the alkenone sediment record are unknown. To gauge the seasonal abundance of these multiple haptophyte species we used a high-throughput DNA sequencing approach. We collected bi-weekly water samples at three different depths in the photic zone (0m, 5m, 10m) from late April through bloom termination in early August. Using 18S rRNA gene sequences to determine species identity, we compared water sample microbial communities with water sample alkenone signatures. Additionally, we cultivated Lake George haptophyte isolates in pure and mixed cultures to define their Uk37 temperature calibrations. During the course of the seasonal cycle, total concentrations of alkenones demonstrated a distinct peak approximately five weeks after their first appearance in the water column. The peak bloom water samples were characterized by abundant tetraunsaturated (C37:4) alkenones in resemblance to the Lake George sediment records. As the bloom declined, the C37:4 alkenones declined in abundance. This variation in water column alkenone signature was reflected in the relative abundance of Hap-A and Hap-B, with Hap-B dominating during bloom peak. Our culture work determined that these multiple haptophyte isolates required individual Uk37 calibrations that differ from the Lake George in situ Uk37 calibration. Lake George sediment alkenone records are therefore composites of multiple, co-occurring haptophyte temperature records. This study is the first next-generation DNA sequencing effort to analyze the microbial community during a haptophyte bloom, and together with

  9. The PRISM palaeoclimate reconstruction and Pliocene sea-surface temperature

    USGS Publications Warehouse

    Dowsett, H.J.

    2007-01-01

    In this paper, I present a summary of the Pliocene Research, Interpretation and Synoptic Mapping (PRISM) palaeoenvironmental reconstruction, with emphasis on its historical development and range of boundary condition datasets. Sea-surface temperature (SST), sea level, sea ice, land cover (vegetation and ice) and topography are discussed as well as many of the assumptions required to create an integrated global-scale reconstruction. New multiproxy research shows good general agreement on the magnitude of mid-Pliocene SST warming. Future directions, including maximum and minimum SST analyses and deep ocean temperature estimates aimed at a full three-dimensional reconstruction, are presented. ?? The Micropalaeontological Society 2007.

  10. 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.

  11. An atlas of monthly mean distributions of GEOSAT sea surface height, SSMI surface wind speed, AVHRR/2 sea surface temperature, and ECMWF surface wind components during 1988

    NASA Technical Reports Server (NTRS)

    Halpern, D.; Zlotnicki, V.; Newman, J.; Brown, O.; Wentz, F.

    1991-01-01

    Monthly mean global distributions for 1988 are presented with a common color scale and geographical map. Distributions are included for sea surface height variation estimated from GEOSAT; surface wind speed estimated from the Special Sensor Microwave Imager on the Defense Meteorological Satellite Program spacecraft; sea surface temperature estimated from the Advanced Very High Resolution Radiometer on NOAA spacecrafts; and the Cartesian components of the 10m height wind vector computed by the European Center for Medium Range Weather Forecasting. Charts of monthly mean value, sampling distribution, and standard deviation value are displayed. Annual mean distributions are displayed.

  12. Satellite-derived sea surface height and sea surface wind data fusion for spilled oil tracking

    NASA Astrophysics Data System (ADS)

    Kozai, K.

    Data fusion is defined as a framework with the purpose of obtaining information of 'greater quality'. Within the framework tools are expressed for the alliance of data originating from different sources. The exact definition of 'greater quality' is stated in this context as more reliable prediction for the trajectory of spilled oil from two different microwave sensor data, namely ERS-2 altimeter and ADEOS/NSCAT scatterometer data. An example is presented in the case of trajectory of bow section and associated oil upwelling from the sunken tanker Nakhodka occurred from January to June in 1997 in Japan Sea. Spill distance is defined as a horizontal distance from the oil upwelling point to the location of sunken Nakhodka and a spill direction is defined as an angle made by the geographic north and the line corresponding to the spill distance. Geostrophic current vectors are derived from ERS-2 altimeter and wind-induced current vectors are derived from ADEOS/NSCAT scatterometer data. These two different satellite-derived vectors are 'fused' together in the surface current model to estimate and evaluate the trajectory of bow section and associated oil upwelling from the sunken tanker Nakhodka. Result of comparison between the estimated and the observed trajectory of bow section indicates that the estimated trajectory is agreed well with the observed one in the first half of drift period, while in the latter half of drift period the estimated trajectory is not agreed well with the observed one, which may be attributable to changes of wind directions within 24 hours from the satellite overpasses. Moreover the comparison between spill vector and 'fused' surface current vector shows the good correspondence in terms of direction when in situ wind accelerates the surface current vector, while the comparison between the twos shows the bad correspondence when the temporal changes of wind vector occurs.

  13. Paleogene biomarker records from the central Arctic Ocean (Integrated Ocean Drilling Program Expedition 302): Organic carbon sources, anoxia, and sea surface temperature

    NASA Astrophysics Data System (ADS)

    Weller, Petra; Stein, Ruediger

    2008-03-01

    During Integrated Ocean Drilling Program Expedition 302 (Arctic Coring Expedition (ACEX)) a more than 200 m thick sequence of Paleogene organic carbon (OC)-rich (black shale type) sediments was drilled. Here we present new biomarker data determined in ACEX sediment samples to decipher processes controlling OC accumulation and their paleoenvironmental significance during periods of Paleogene global warmth and proposed increased freshwater discharge in the early Cenozoic. Specific source-related biomarkers including n-alkanes, fatty acids, isoprenoids, carotenoids, hopanes/hopenes, hopanoic acids, aromatic terpenoids, and long-chain alkenones show a high variability of components, derived from marine and terrestrial origin. The distribution of hopanoic acid isomers is dominated by compounds with the biological 17β(H), 21β(H) configuration indicating a low level of maturity. On the basis of the biomarker data the terrestrial OC supply was significantly enriched during the late Paleocene and part of the earliest Eocene, whereas increased aquatic contributions and euxinic conditions of variable intensity were determined for the Paleocene-Eocene thermal maximum and Eocene thermal maximum 2 events as well as the middle Eocene time interval. Furthermore, samples from the middle Eocene are characterized by the occurrence of long-chain alkenones, high proportions of lycopane, and high ratios (>0.6) of (n-C35 + lycopane)/n-C31. The occurrence of C37-alkenenones, which were first determined toward the end of the Azolla freshwater event, indicates that the OC becomes more marine in origin during the middle Eocene. Preliminary U37K'-based sea surface temperature (SST) values display a long-term temperature decrease of about 15°C during the time interval 49-44.5 Ma (25° to 10°C), coinciding with the global benthic δ18O cooling trend after the early Eocene climatic optimum. At about 46 Ma, parallel with onset of ice-rafted debris, SST (interpreted as summer temperatures

  14. Sea surface temperatures from the southern Benguela region from the Pliocene and Pleistocene: tracking Agulhas Current input into the SE Atlantic

    NASA Astrophysics Data System (ADS)

    Petrick, B. F.; McClymont, E.; Felder, S.; Lloyd, J. M.; Leng, M. J.

    2011-12-01

    The Pliocene and-Pleistocene epochs provide a way to understand the effect of past climate changes on key ocean currents. Here, we show results from ODP Site1087 (31.28'S, 15.19'E, 1374m water depth) to investigate changes in ocean circulation over the period of the mid-Pliocene warm period 3.0-3.5 Ma and compare these to the time of the 100 kyr Pleistocene glacial cycles. ODP 1087 is located in the South-eastern Atlantic Ocean, outside of the Benguela upwelling region; reconstructing the temperature history of the site will therefore provide an important data set from a part of the ocean that has few orbital-scale and continuous Pliocene temperature reconstructions. ODP 1087 can be used to investigate the history of the heat and salt transfer to the Atlantic Ocean from the Indian Ocean via the Agulhas Retroflection, which plays an important part in the global thermohaline circulation (Lutjeharms, 2007). Climate models and reconstructions for the most recent glacial-interglacial cycles have shown that changes to the strength of the heat transfer may cause major climatic changes and may play a role in transitions from glacial to interglacial events (Knorr & Lohmann, 2003). It is unknown how this transfer reacted to generally warmer global temperatures during the mid-Pliocene. Because the mid-Pliocene is seen as a model for future climate change it might provide a model for ocean circulations in a warmer world. Our approach is to apply several organic geochemistry proxies and foraminiferal analyses to reconstruct the history of ODP 1087. The UK37' index records differences in the unsaturated bonds in the C37 alkenones to reconstruct sea surface temperatures (Brassell et al., 1986). We present SSTs generated for the mid-Pliocene Warm period with a resolution of 4000 years. We compare this data to the time of the 100 kyr glacial cycles during the late Pleistocene. Even though ODP 1087 is located outside the Benguela upwelling system, it has lower Pliocene temperatures

  15. The interannual oscillation of sea surface temperature in the South China Sea

    SciTech Connect

    Zhou Faxiu; Yu Shenyu; Fu Gang; Wang Dongxiao

    1994-12-31

    The South China Sea (SCS) is located in the area of the Asia monsoons and is a quasi-closed deep basin near the tropical western Pacific. The sea surface temperature anomalies (SSTA) in the South China Sea have an influence on the precipitation in flood season in the South China. The anomalies of the Asia monsoons have great effect on SST in the SCS. This paper aims at finding the features of the interannual oscillation of SST and discussing the mechanism of the SST oscillation in the SCS.

  16. Macrofauna under sea ice and in the open surface layer of the Lazarev Sea, Southern Ocean

    NASA Astrophysics Data System (ADS)

    Flores, Hauke; van Franeker, Jan-Andries; Cisewski, Boris; Leach, Harry; Van de Putte, Anton P.; Meesters, Erik (H. W. G.); Bathmann, Ulrich; Wolff, Wim J.

    2011-10-01

    A new fishing gear was used to sample the macrozooplankton and micronekton community in the surface layer (0-2 m) under ice and in open water, the Surface and Under Ice Trawl (SUIT). In total, 57 quantitative hauls were conducted in the Lazarev Sea (Southern Ocean) during 3 different seasons (autumn 2004, winter 2006, summer 2007/2008). At least 46 species from eight phyla were caught in all 3 seasons combined. Biomass density was dominated by Antarctic krill Euphausia superba. The average biomass density was highest under the winter sea ice and lowest under the young ice in autumn. In summer, macrozooplankton biomass was dominated by ctenophores in open water and by Antarctic krill under ice. The community composition varied significantly among seasons, and according to the presence of sea ice. The response of the community composition to the presence of sea ice was influenced by species that were significantly more abundant in open water than under ice ( Cyllopus lucasii, Hyperiella dilatata), only seasonally abundant under ice ( Clione antarctica), or significantly associated with sea ice ( Eusirus laticarpus). A number of abundant species showed distinct diel patterns in the surface occurrence both under ice and in open water, indicating that the surface layer serves as a foraging ground predominantly at night. Our results emphasize the potential of a number of non-euphausiid macrozooplankton and micronekton species to act as energy transmitters between the production of sea ice biota and the pelagic food web. By providing a regional-scale quantitative record of macrofauna under Antarctic sea ice covering 3 seasons, this study adds new and direct evidence that the ice-water interface layer is a major functional node in the ecosystem of the Antarctic seasonal sea ice zone.

  17. Calving seismicity from iceberg-sea surface interactions

    USGS Publications Warehouse

    Bartholomaus, T.C.; Larsen, C.F.; O'Neel, S.; West, M.E.

    2012-01-01

    Iceberg calving is known to release substantial seismic energy, but little is known about the specific mechanisms that produce calving icequakes. At Yahtse Glacier, a tidewater glacier on the Gulf of Alaska, we draw upon a local network of seismometers and focus on 80 hours of concurrent, direct observation of the terminus to show that calving is the dominant source of seismicity. To elucidate seismogenic mechanisms, we synchronized video and seismograms to reveal that the majority of seismic energy is produced during iceberg interactions with the sea surface. Icequake peak amplitudes coincide with the emergence of high velocity jets of water and ice from the fjord after the complete submergence of falling icebergs below sea level. These icequakes have dominant frequencies between 1 and 3 Hz. Detachment of an iceberg from the terminus produces comparatively weak seismic waves at frequencies between 5 and 20 Hz. Our observations allow us to suggest that the most powerful sources of calving icequakes at Yahtse Glacier include iceberg-sea surface impact, deceleration under the influence of drag and buoyancy, and cavitation. Numerical simulations of seismogenesis during iceberg-sea surface interactions support our observational evidence. Our new understanding of iceberg-sea surface interactions allows us to reattribute the sources of calving seismicity identified in earlier studies and offer guidance for the future use of seismology in monitoring iceberg calving.

  18. Sea ice concentration temporal variability over the Weddell Sea and its relationship with tropical sea surface temperature

    USGS Publications Warehouse

    Barreira, S.; Compagnucci, R.

    2007-01-01

    Principal Components Analysis (PCA) in S-Mode (correlation between temporal series) was performed on sea ice monthly anomalies, in order to investigate which are the main temporal patterns, where are the homogenous areas located and how are they related to the sea surface temperature (SST). This analysis provides 9 patterns (4 in the Amundsen and Bellingshausen Seas and 5 in the Weddell Sea) that represent the most important temporal features that dominated sea ice concentration anomalies (SICA) variability in the Weddell, Amundsen and Bellingshausen Seas over the 1979-2000 period. Monthly Polar Gridded Sea Ice Concentrations data set derived from satellite information generated by NASA Team algorithm and acquired from the National Snow and Ice Data Center (NSIDC) were used. Monthly means SST are provided by the National Center for Environmental Prediction reanalysis. The first temporal pattern series obtained by PCA has its homogeneous area located at the external region of the Weddell and Bellingshausen Seas and Drake Passage, mostly north of 60°S. The second region is centered in 30°W and located at the southeast of the Weddell. The third area is localized east of 30°W and north of 60°S. South of the first area, the fourth PC series has its homogenous region, between 30° and 60°W. The last area is centered at 0° W and south of 60°S. Correlation charts between the five Principal Components series and SST were performed. Positive correlations over the Tropical Pacific Ocean were found for the five PCs when SST series preceded SICA PC series. The sign of the correlation could relate the occurrence of an El Niño/Southern Oscillation (ENSO) warm (cold) event with posterior positive (negative) anomalies of sea ice concentration over the Weddell Sea.

  19. Sea surface temperature of the coastal zones of France

    NASA Technical Reports Server (NTRS)

    Deschamps, P. Y.; Crepon, M.; Monget, J. M.; Verger, F. (Principal Investigator); Frouin, R.; Cassanet, J.; Wald, L.

    1982-01-01

    Thermal gradients in French coastal zones for the period of one year were mapped in order to enable a coherent study of certain oceanic features detectable by the variations in the sea surface temperature field and their evolution in time. The phenomena examined were mesoscale thermal features in the English Channel, the Bay of Biscay, and the northwestern Mediterranean; thermal gradients generated by French estuary systems; and diurnal heating in the sea surface layer. The investigation was based on Heat Capacity Mapping Mission imagery.

  20. Determination of sea surface temperatures from microwave and IR data

    NASA Technical Reports Server (NTRS)

    Rangaswamy, S.; Grover, J.

    1982-01-01

    Microwave measurements from the Nimbus 7 SMMR were used to derive the atmospheric precipitable water, which was then used to obtain the atmospheric correction for use with AVHRR thermal IR measurements to obtain sea surface temperature (SST). The resulting SST's were compared with the NOAA operational sea surface temperature measurements, and the two sets of measurements were found to be in reasonable agreement. The average residuals between the two sets of measurements was 0.15 K with the NOAA operational SST's being slightly greater.

  1. 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.

  2. 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

  3. 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

  4. Spatial and temporal variability of sea-surface temperature fronts in the coastal Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Mustapha, Sélima Ben; Larouche, Pierre; Dubois, Jean-Marie

    2016-08-01

    An analysis of 11 years of sea surface temperatures images allowed the determination of the frontal occurrence probability in the southeastern Beaufort Sea using the single-image edge detection method. Results showed that, as the season progresses, fronts become more detectable due to solar heating of the surface layer. Some recurrent features can be identified in the summer time frontal climatology such as the Mackenzie River plume front, the Cape Bathurst front, the Mackenzie Trough front and the Amundsen Gulf front. These areas may be playing an important role in the biological processes acting as drivers to local enhanced biological productivity.

  5. Lithospheric structure of South China Sea from surface wave tomography

    NASA Astrophysics Data System (ADS)

    Chen, L.; Xue, M.; Le, K.; Yang, T.

    2011-12-01

    The South China Sea is one of the marginal seas of the West Pacific where the Eurasian Plate, Philippine Sea Plate, Pacific Plate and Indo-Australian Plate interact. In this study we give a 3D shear wave velocity structure of South China Sea using surface wave tomographic methods. We use earthquakes distributed on the periphery of the South China Sea and collect the earthquake data from 48 stations (IRIS stations, CDSN stations and four stations deployed in Vietnam by Tongji University) with rays up to ~ 3000. We first calculate the group velocity dispersion curves of fundamental mode for Rayleigh waves with periods from 14 sec to 130 sec using the multiple filter technique. After getting the dispersion curve between each station-to-source pair, we conduct an inversion to get group velocity at each grid point in the rectangular region of 14° s - 34° N and 86° E - 134° E with different grid spacing of 2° × 2° and 1° × 1°. This process is done by the fast marching method as the forward step and then subspace inversion step followed. When we get the group velocity of each grid point for corresponding periods, we can extract a dispersion curve for that point. Through the surface wave inversion which uses Knopoff's calculation method for layered medium as the forward step and the damped least square method as the inversion step followed, we can get an iterative model which carries the information of shear wave velocity and layer depth for each grid point. Finally we put all the shear wave velocity structures of all points together to obtain the three-dimensional shear wave structures. With checkboard tests indicating good resolution, we find that higher group velocities persistently show up in South China Sea Basin, West Philippine Sea Basin, and Celebes Sea Basin from periods of 20 sec to 60 sec, which reflect structures down to 20 - 60 km deep. Similar high shear velocity features also show up in depth slices from 30 km to 60 km. These high shear velocity

  6. The Aquarius Mission: Sea Surface Salinity from Space

    NASA Technical Reports Server (NTRS)

    Koblinsky, Chester; Chao, Y.; deCharon, A.; Edelstein, W.; Hildebrand, P.; Lagerloef, G.; LeVine, D.; Pellerano, F.; Rahmat-Samii, Y.; Ruf, C.

    2001-01-01

    Aquarius is a new satellite mission concept to study the impact of the global water cycle on the ocean, including the response of the ocean to buoyancy forcing and the subsequent feedback of the ocean on the climate. The measurement objective of Aquarius is sea surface salinity, which reflects the concentration of freshwater at the ocean surface. Salinity affects the dielectric constant of sea water and, consequently, the radiometric emission of the sea surface to space. Rudimentary space observations with an L-band radiometer were first made from Skylab in the mid-70s and numerous aircraft missions of increasing quality and improved technology have been conducted since then. Technology is now available to carry out a global mission, which includes both an accurate L band (1.413 Ghz) radiometer and radar system in space and a global array of in situ observations for calibration and validation, in order to address key NASA Earth Science Enterprise questions about the global cycling of water and the response of the ocean circulation to climate change. The key scientific objectives of Aquarius examine the cycling of water at the ocean's surface, the response of the ocean circulation to buoyancy forcing, and the impact of buoyancy forcing on the ocean's thermal feedback to the climate. Global surface salinity will also improve our ability to model the surface solubility chemistry needed to estimate the air-sea exchange of CO2. In order to meet these science objectives, the NASA Salinity Sea Ice Working Group over the past three years has concluded that the mission measurement goals should be better than 0.2 practical salinity units (psu) accuracy, 100 km resolution, and weekly to revisits. The Aquarius mission proposes to meet these measurement requirements through a real aperture dual-polarized L band radiometer and radar system. This system can achieve the less than 0.1 K radiometric temperature measurement accuracy that is required. A 3 m antenna at approx. 600km

  7. Polarized infrared emissivity of one-dimensional Gaussian sea surfaces with surface reflections.

    PubMed

    Li, Hongkun; Pinel, Nicolas; Bourlier, Christophe

    2011-08-10

    Surface reflection is an important phenomenon that must be taken into account when studying sea surface infrared emissivity, especially at large observation angles. This paper models analytically the polarized infrared emissivity of one-dimensional sea surfaces with shadowing effect and one surface reflection, by assuming a Gaussian surface slope distribution. A Monte Carlo ray-tracing method is employed as a reference. It is shown that the present model agrees well with the reference method. The emissivity calculated by the present model is then compared with measurements. The comparisons show that agreements are greatly improved by taking one surface reflection into account. The Monte Carlo ray-tracing results of sea surface infrared emissivity with two and three reflections are also determined. Their contributions are shown to be negligible.

  8. Sea-surface and deep-magnetic data at Vavilov Seamount, Tyrrhenian Sea

    NASA Astrophysics Data System (ADS)

    Muccini, Filippo; Cocchi, Luca; Locritani, Marina; Carmisciano, Cosmo

    2016-04-01

    Sea surface and deep magnetic data were acquired at Vavilov seamount, in the Tyrrhenian sea. Vavilov seamount is located in the central portion of the homonymous Vavilov basin. The seamount stands about 2800 meters above the seafloor at 3600 meters depth, with the top at about 800 meters below the sea level. Oceanization of the basin occurred during the Late Miocene-Early Pliocene. The magnetic data were collected in 2011 on board the Nave Ammiraglio Magnaghi by using a Marine Magnetics Seaspy magnetometer. The sea surface magnetic survey was realized with two different grids: the first regional one, with 13 parallel lines about 43 Km long, 3 Km spaced (104° N oriented) and 6 tie control lines about 40 Km long, 5 Km spaced (014° N oriented). The second one was realized to better define the volcanic structure of the seamount, and was achieved by acquiring 12 magnetic parallel lines (104° N), 18 Km long and 1 Km spaced. The deep magnetic data were collected by towing a magnetic sensor coupled with a L3 sidescan sonar Klein 3000. A set of 5 parallel lines were acquired in correspondence of the bathymetric top of the seamount with the sensor flying at about constant depth of 700 meters. These data represents the first near-bottom magnetic data collected for Vavilov seamount and it allows comparison between sea-surface and deep magnetic data.

  9. Sea Surface Salinity: The Next Remote Sensing Challenge

    NASA Technical Reports Server (NTRS)

    Lagerloef, Gary S. E.; Swift, Calvin T.; LeVine, David M.

    1995-01-01

    A brief history of salinity remote sensing is presented. The role of sea surface salinity (SSS) in the far north Atlantic and the influence of salinity variations on upper ocean dynamics in the tropics are described. An assessment of the present state of the technology of the SSS satellite remote sensing is given.

  10. Three-way partitioning of sea surface temperature measurement error

    NASA Technical Reports Server (NTRS)

    Chelton, D.

    1983-01-01

    Given any set of three 2 degree binned anomaly sea surface temperature (SST) data sets by three different sensors, estimates of the mean square error of each sensor estimate is made. The above formalism performed on every possible triplet of sensors. A separate table of error estimates is then constructed for each sensor.

  11. Skylab earth resources experiment package /EREP/ - Sea surface topography experiment

    NASA Technical Reports Server (NTRS)

    Vonbun, F. O.; Marsh, J. G.; Mcgoogan, J. T.; Leitao, C. D.; Vincent, S.; Wells, W. T.

    1976-01-01

    The S-193 Skylab radar altimeter was operated in a round-the-world pass on Jan. 31, 1974. The main purpose of this experiment was to test and 'measure' the variation of the sea surface topography using the Goddard Space Flight Center (GSFC) geoid model as a reference. This model is based upon 430,000 satellite and 25,000 ground gravity observations. Variations of the sea surface on the order of -40 to +60 m were observed along this pass. The 'computed' and 'measured' sea surfaces have an rms agreement on the order of 7 m. This is quite satisfactory, considering that this was the first time the sea surface has been observed directly over a distance of nearly 35,000 km and compared to a computed model. The Skylab orbit for this global pass was computed using the Goddard Earth Model (GEM 6) and S-band radar tracking data, resulting in an orbital height uncertainty of better than 5 m over one orbital period.

  12. Mean Sea Surface (mss) Model Determination for Malaysian Seas Using Multi-Mission Satellite Altimeter

    NASA Astrophysics Data System (ADS)

    Yahaya, N. A. Z.; Musa, T. A.; Omar, K. M.; Din, A. H. M.; Omar, A. H.; Tugi, A.; Yazid, N. M.; Abdullah, N. M.; Wahab, M. I. A.

    2016-09-01

    The advancement of satellite altimeter technology has generated many evolutions to oceanographic and geophysical studies. A multi-mission satellite altimeter consists with TOPEX, Jason-1 and Jason-2, ERS-2, Envisat-1, CryoSat-2 and Saral are extracted in this study and has been processed using Radar Altimeter Database System (RADS) for the period of January 2005 to December 2015 to produce the sea surface height (hereinafter referred to SSH). The monthly climatology data from SSH is generated and averaged to understand the variation of SSH during monsoon season. Then, SSH data are required to determine the localised and new mean sea surface (MSS). The differences between Localised MSS and DTU13 MSS Global Model is plotted with root mean square error value is 2.217 metres. The localised MSS is important towards several applications for instance, as a reference for sea level variation, bathymetry prediction and derivation of mean dynamic topography.

  13. Anomalous sea surface structures as an object of statistical topography.

    PubMed

    Klyatskin, V I; Koshel, K V

    2015-06-01

    By exploiting ideas of statistical topography, we analyze the stochastic boundary problem of emergence of anomalous high structures on the sea surface. The kinematic boundary condition on the sea surface is assumed to be a closed stochastic quasilinear equation. Applying the stochastic Liouville equation, and presuming the stochastic nature of a given hydrodynamic velocity field within the diffusion approximation, we derive an equation for a spatially single-point, simultaneous joint probability density of the surface elevation field and its gradient. An important feature of the model is that it accounts for stochastic bottom irregularities as one, but not a single, perturbation. Hence, we address the assumption of the infinitely deep ocean to obtain statistic features of the surface elevation field and the squared elevation gradient field. According to the calculations, we show that clustering in the absolute surface elevation gradient field happens with the unit probability. It results in the emergence of rare events such as anomalous high structures and deep gaps on the sea surface almost in every realization of a stochastic velocity field. PMID:26172788

  14. SeaRover: An Emerging Technology for Sea Surface Sensor Networks

    NASA Astrophysics Data System (ADS)

    Fong, T.; Kudela, R.; Curcio, J.; Davidson, K.; Darling, D.; Kirkwood, B.

    2005-12-01

    Introduction - SeaRover is envisioned as an autonomous surface vehicle (ASV) for coastal operations. It is intended to lower the cost of existing marine survey applications while enabling new science missions. The current conceptual design is a small vehicle with hull and propulsion system optimized to eliminate cavitation and EM noise. SeaRover will make significant advances over existing platforms by providing longer duration science missions, better positioning and mission control, larger power budgets for instrumentation and significantly lower operational costs than existing vehicles. Science Enabled by SeaRover - SeaRover's unique design and autonomous capability provides several advantages compared to traditional autonomous underwater vehicles (AUV's) and crewed surface vessels: (1) Near surface sampling: SeaRover can sample within the top 1-2 meters. This is difficult to do with crewed vessels because of draft and perturbations from the hull. (2) Adaptive monitoring of dynamic events: SeaRover will be capable of intelligent decision making, as well as real-time remote control. This will enable highly-responsive autonomous tracking of moving phenomena (e.g., algal bloom). (3) Long term monitoring: SeaRover can be deployed for extended periods of time, allowing it to be used for longitudinal baseline studies. SeaRover will represent an advance over existing platforms in terms of: (1) Mobility: operational range from 10-1000 km, GPS accuracy, trajectory control with meter precision, and launch in hours. (2) Duration: from days up to months. (3) Payload and Power: accommodate approximately 100 kg for a 6m hull. Its surface design will allow access to wind and sun energy. (4) Communication: radio, wireless, satellite, direct data return. (5) Operational Cost: target costs are $2K/day (24 hour operation), with no onboard operator. (6) Recovery/Reusability: autonomous return to safe harbor provides sample return and on-base maintenance. Large science and power

  15. Sea surface temperature modelling in the Sea of Iroise: assessment of boundary conditions

    NASA Astrophysics Data System (ADS)

    Guillou, Nicolas; Chapalain, Georges; Duvieilbourg, Eric

    2013-07-01

    The present study investigates the sensitivity of the COupled Hydrodynamical-Ecological model for REgioNal and Shelf seas (COHERENS) to predict sea surface temperature (SST) patterns in the Sea of Iroise (western end of French Brittany) in relation to the spatial and temporal resolutions of open boundary conditions (OBCs). Two sources of daily operational OBCs of temperature are considered, derived from (1) the Mercator Global Ocean and (2) the Iberian Biscay Irish analysis and forecasting systems delivering predictions at spatial resolutions of 1/12° and 1/36°, respectively. Coastal model performance is evaluated by comparing SST predictions with recently available field data collected (1) along the route of a vessel travelling between the coast and the isle of Ushant and (2) at two offshore stations. The comparison is extended to SST spatial distribution derived from remote-sensing observations. The influence of OBC spatial resolution is exhibited in the north-eastern area of the Sea of Iroise in relation to the intrusion of cold surface waters. OBC temporal resolution is found to have a lower impact advocating for the implementation of climatological temperature forcings to predict major SST patterns in the Sea of Iroise.

  16. Air-sea interaction and surface flux in non-equilibrium sea-states

    SciTech Connect

    Levy, G.; Ek, M.; Mahrt, L.

    1994-12-31

    The wind forcing over the ocean determines the air-sea exchanges of heat, moisture and momentum which affect and drive the surface wave dynamics and the mixed layer circulation. In turn, it has been shown that wave dynamics and wave age affect ocean surface roughness and air-sea exchange processes so that the wind flow is not always in equilibrium with the ocean surface waves. This effect of wave spectrum on surface roughness has been discussed by many authors; yet it is rarely, if ever, accounted for in flux parameterization in models of the marine atmospheric boundary layer (MABL). Proper representation of these effects in both remote sensors` signal to geophysical-parameter models and in physical models of the ocean and the atmosphere on all scales is essential given the increased reliance of ocean monitoring systems on remote sea-surface sensors and the fundamental sensitivity of physical models to surface fluxes. In this paper the authors present a methodology for modeling these effects from data along with some results from data analyses of observations taken in two field experiments.

  17. On model differences and skill in predicting sea surface temperature in the Nordic and Barents Seas

    NASA Astrophysics Data System (ADS)

    Langehaug, H. R.; Matei, D.; Eldevik, T.; Lohmann, K.; Gao, Y.

    2016-04-01

    The Nordic Seas and the Barents Sea is the Atlantic Ocean's gateway to the Arctic Ocean, and the Gulf Stream's northern extension brings large amounts of heat into this region and modulates climate in northwestern Europe. We have investigated the predictive skill of initialized hindcast simulations performed with three state-of-the-art climate prediction models within the CMIP5-framework, focusing on sea surface temperature (SST) in the Nordic Seas and Barents Sea, but also on sea ice extent, and the subpolar North Atlantic upstream. The hindcasts are compared with observation-based SST for the period 1961-2010. All models have significant predictive skill in specific regions at certain lead times. However, among the three models there is little consistency concerning which regions that display predictive skill and at what lead times. For instance, in the eastern Nordic Seas, only one model has significant skill in predicting observed SST variability at longer lead times (7-10 years). This region is of particular promise in terms of predictability, as observed thermohaline anomalies progress from the subpolar North Atlantic to the Fram Strait within the time frame of a couple of years. In the same model, predictive skill appears to move northward along a similar route as forecast time progresses. We attribute this to the northward advection of SST anomalies, contributing to skill at longer lead times in the eastern Nordic Seas. The skill at these lead times in particular beats that of persistence forecast, again indicating the potential role of ocean circulation as a source for skill. Furthermore, we discuss possible explanations for the difference in skill among models, such as different model resolutions, initialization techniques, and model climatologies and variance.

  18. Microhydrodynamics of flotation processes in the sea surface layer

    NASA Astrophysics Data System (ADS)

    Grammatika, Marianne; Zimmerman, William B.

    2001-10-01

    The uppermost surface of the ocean forms a peculiarly important ecosystem, the sea surface microlayer (SML). Comprising the top 1-1000 μm of the ocean surface, the SML concentrates many chemical substances, particularly those that are surface active. Important economically as a nursery for fish eggs and larvae, the SML unfortunately is also especially vulnerable to pollution. Contaminants that settle out from the air, have low solubility, or attach to floatable matter tend to accumulate in the SML. Bubbles contribute prominently to the dynamics of air-sea exchanges, playing an important role in geochemical cycling of material in the upper ocean and SML. In addition to the movement of bubbles, the development of a bubble cloud interrelates with the single particle dynamics of all other bubbles and particles. In the early sixties, several in situ oceanographic techniques revealed an "unbelievably immense" number of coastal bubbles of radius 15-300 μm. The spatial and temporal variation of bubble numbers were studied; acoustical oceanographers now use bubbles as tracers to determine ocean processes near the ocean surface. Sea state and rain noises have both been definitively ascribed to the radiation from huge numbers of infant micro bubbles [The Acoustic Bubble. Academic Press, San Diego]. Our research programme aims at constructing a hydrodynamic model for particle transport processes occurring at the microscale, in multi-phase flotation suspensions. Current research addresses bubble and floc microhydrodynamics as building blocks for a microscale transport model. This paper reviews sea surface transport processes in the microlayer and the lower atmosphere, and identifies those amenable to microhydrodynamic modelling and simulation. It presents preliminary simulation results including the multi-body hydrodynamic mobility functions for the modelling of "dynamic bubble filters" and floc suspensions. Hydrodynamic interactions versus spatial anisotropy and size of

  19. Holocene Sea Surface Conditions in the Nordic Seas According to Dinocyst Assemblages

    NASA Astrophysics Data System (ADS)

    Van Nieuwenhove, N.; Baumann, A.; Bonnet, S.; Matthiessen, J. J.; de Vernal, A.; Bauch, H. A.; Hillaire-Marcel, C.

    2014-12-01

    The Holocene evolution of the upper ocean in the Nordic Seas is assessed based on the qualitative and quantitative evaluation of 16 dinoflagellate cyst (dinocyst) records retrieved from the warm and saline Atlantic Domain in the east, across the seasonally sea-ice covered Arctic Domain, to the Arctic-outflow influenced Polar Domain in the west. First signs of interglacial conditions are observed from ~11.5 ka BP onwards in the Atlantic Domain, and expanded time-transgressively westward, with deglacial processes appearing to have persisted ~2 kyr longer in the west. No clear peak warming can be observed in the dinocyst data during the interval that is generally considered to correspond to the Holocene climatic optimum, and the disparity between the dinocyst and other phytoplankton records suggests a pronounced seasonality at that time. A slightly freshened upper ocean appears to have facilitated seasonal sea ice formation even at the Vøring Plateau. Despite the strongly contrasting environmental conditions across the Nordic Seas, a basin-wide uniform change in the assemblage compositions is seen between ~7 and 6.1 ka BP, and appears to be linked to the establishment of the modern surface circulation pattern. Potential density estimates for the surface water close to modern convection sites reveals values that would imply an increased likeliness of dense enough surface waters to permit sinking from that time onwards. The changes in the Nordic Seas appear to follow a similar reorganisation in the Labrador Sea and the onset of strong winter convection there. Finally, a gradual eastward expansion of the Arctic Domain can be observed from ~4.5 ka BP onwards, with a delayed consequent reaction of the Atlantic-sourced water inflow at the Vøring Plateau showing a slight recovery of cool taxa from ~2.4 ka BP onwards.

  20. Organic biomarker records spanning the last 34,800 years from the southeastern Brazilian upper slope: links between sea surface temperature, displacement of the Brazil Current, and marine productivity

    NASA Astrophysics Data System (ADS)

    Lourenço, Rafael André; de Mahiques, Michel Michaelovitch; Wainer, Ilana Elazari Klein Coaracy; Rosell-Melé, Antoni; Bícego, Márcia Caruso

    2016-06-01

    Collective assessment of marine and terrigenous organic biomarkers was performed on a sediment core spanning the last 34,800 years on the upper slope southeast of Brazil to verify the signatures of climatic variations in sea surface temperature (SST), marine productivity, and the flux of terrigenous material in this region. This evaluation is based on marine and terrigenous proxies including alkenones, chlorins, aliphatic hydrocarbons, n-alcohols, and fatty acids. This first report of organic biomarker data for this region confirms a correlation between SST, changes in terrigenous organic matter flow into the ocean, and marine productivity over the last 34.8 ka as a response to the displacement of the Brazil Current. Conditions prevailing during marine isotopic stage (MIS) 3 may be considered intermediate between the last glacial maximum (LGM) and the Late Holocene. For MIS 2, a period of low relative sea level, it was verified that the lowest SSTs were associated with the LGM and higher marine productivity. SST increased by up to 4.4 °C between the LGM and the Holocene. This reveals synchronicity between SST on the southeastern Brazilian upper slope and the North Atlantic Ocean SST records reported in earlier studies.

  1. Organic biomarker records spanning the last 34,800 years from the southeastern Brazilian upper slope: links between sea surface temperature, displacement of the Brazil Current, and marine productivity

    NASA Astrophysics Data System (ADS)

    Lourenço, Rafael André; de Mahiques, Michel Michaelovitch; Wainer, Ilana Elazari Klein Coaracy; Rosell-Melé, Antoni; Bícego, Márcia Caruso

    2016-10-01

    Collective assessment of marine and terrigenous organic biomarkers was performed on a sediment core spanning the last 34,800 years on the upper slope southeast of Brazil to verify the signatures of climatic variations in sea surface temperature (SST), marine productivity, and the flux of terrigenous material in this region. This evaluation is based on marine and terrigenous proxies including alkenones, chlorins, aliphatic hydrocarbons, n-alcohols, and fatty acids. This first report of organic biomarker data for this region confirms a correlation between SST, changes in terrigenous organic matter flow into the ocean, and marine productivity over the last 34.8 ka as a response to the displacement of the Brazil Current. Conditions prevailing during marine isotopic stage (MIS) 3 may be considered intermediate between the last glacial maximum (LGM) and the Late Holocene. For MIS 2, a period of low relative sea level, it was verified that the lowest SSTs were associated with the LGM and higher marine productivity. SST increased by up to 4.4 °C between the LGM and the Holocene. This reveals synchronicity between SST on the southeastern Brazilian upper slope and the North Atlantic Ocean SST records reported in earlier studies.

  2. Sea ice and surface water circulation, Alaskan continental shelf

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  3. Covariation of Mesoscale Ocean Color and Sea-Surface Temperature Patterns in the Sargasso Sea

    NASA Technical Reports Server (NTRS)

    McGillicuddy, Dennis J., Jr.; Kosnyrev, V. K.; Ryan, J. P.; Yoder, J. A.

    2001-01-01

    During the lifetime of the Coastal Zone Color Scanner, there were 21 instances in which both satellite-derived ocean color and sea-surface temperature are simultaneously available over large areas of the Sargasso Sea. These images reveal close correspondence between mesoscale structures observed in temperature and pigment fields. In general, higher (lower) pigment biomass occurs in mesoscale features consisting of cold (warm) temperature anomalies. This relationship is consistent with the idea that upward displacement of isopycnals at the base of the euphotic zone by mesoscale eddies is an important mechanism of nutrient supply in the region.

  4. Arctic sea ice surface ponds due to saltwater impurities

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2012-03-01

    During the summer melt season the white surface of Arctic sea ice turns to a mixture of grays and blues as meltwater ponds come to dot the landscape. Rising temperatures in late spring melt ice and snow, and the meltwater pools in depressions left by drifting snow. In just a week, these meltwater ponds can come to dominate the ice surface, increasing their areal extent by up to 35% per day. But just as quickly as they appear, the pools can recede, the water flowing into the ocean. Surface ponds drastically reduce the ice's albedo, increasing the amount of light available for Arctic ecosystems and accelerating ice melt.

  5. Plio-Pleistocene pCO2 - a Multiproxy Approach Using Alkenone and Boron Based Carbonate System Proxies

    NASA Astrophysics Data System (ADS)

    Foster, G. L.; Seki, O.; Schmidt, D. N.; Kawamura, K.; Pancost, R.

    2008-12-01

    The recent rapid rise in atmospheric CO2 is unprecedented in Earths history, and the current level (385 ppm) is higher than previously experienced for at least the last 650 kyr. Therefore in order to better understand the link between climate and CO2 it is desirable to examine times in the past that experienced similar or higher levels of CO2 compared to today. The Pliocene (2.6 to 5.3 Ma) is the most recent warm period and hence offers such an opportunity. Detailed reconstructions show that global temperatures were 2- 3°C higher ([1], 6°C at high latitudes) and the polar ice sheets were considerably smaller (sea level was 15-20 m higher; [2]) yet other boundary conditions, such as continental configuration, were similar at this time. Earlier studies, typically with low temporal resolution, have shown that at c.3 Ma pCO2 concentrations were in the range 300-400 ppm. A common assumption is that pCO2 dropped from this high value to pre-industrial values at a time coincident with the intensification of northern hemisphere glaciation (NHG) that occurred at c.2.7 Ma, although this has yet to be demonstrated. Here we present a continuous pCO2 record recovered from ocean sediments using a multiproxy approach based on the boron and alkenone carbonate system proxies. This new data allows both a determination of the magnitude of Pliocene pCO2 and for the fist time the Plio-Pleistocene evolution of pCO2 that accompanied the intensification of NHG. We developed continuous records of alkenone based ɛp values and foraminiferal δ11B and B/Ca ratios from ODP Sites 999 and 1000 in the Caribbean Sea and Site 1241 on the western side of the Panama Isthmus in the Eastern Equatorial Pacific spanning the last 5.3 Ma. Following a correction of the alkenone records for coccolith size, and accounting for changing growth rate where appropriate, the alkenone based ɛp record can be used to estimate [CO2]aq and hence pCO2 at the two sites. Similarly, using the core top calibration of [3

  6. Reduced-dimension reconstruction of the equatorial Pacific SST and zonal wind fields over the past 10,000 years using Mg/Ca and alkenone records

    NASA Astrophysics Data System (ADS)

    Gill, Emily C.; Rajagopalan, Balaji; Molnar, Peter; Marchitto, Thomas M.

    2016-07-01

    We develop a multiproxy, reduced-dimension methodology to blend magnesium-calcium (Mg/Ca) and alkenone (U37k) paleo sea surface temperature (SST) records from the eastern and western equatorial Pacific, to recreate snapshots of full field SSTs and zonal winds from 10 to 2 ka B.P. in 2000 year increments. Single-proxy reconstructions (Mg/Ca only versus U37K' only) reveal differences in the timing and duration of maximum cooling across the east-central equatorial Pacific. The largest zonal temperature differences (average west Pacific SST minus average east Pacific SST) occur at 6 ka B.P. for the Mg/Ca-only reconstruction (0.61°C) and at 10 and 4 ka for the U37K'-only reconstruction (0.55°C and 0.47°C, respectively). Disagreements between SST trends suggested by each proxy call for methods that can resolve the common patterns between each and have motivated the work presented in this study. In combining inferences from these proxies, we treat both Mg/Ca and U37K' reconstructions of SST as annual average values, but we recognize that they may be sensitive to different seasons. In the multiproxy reconstruction, the zonal SST difference is largest at 10 ka (0.26°C), with coldest SST anomalies of ˜ -0.9°C in the eastern equatorial Pacific and concurrent easterly maximum zonal wind anomalies of 7 m s-1 throughout the central Pacific. From 10 to 2 ka, the entire equatorial Pacific warms, but at a faster rate in the east than the west, and the average central Pacific easterly winds weaken gradually to approximately 2 m s-1. These patterns are broadly consistent with previous inferences of reduced El Niño-Southern Oscillation variability associated with a "La Niña-like" state during the early to middle Holocene.

  7. Skylab S-193 Radscat microwave measurements of sea surface winds

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Fung, A. K.; Young, J. D.; Claassen, J. P.; Chan, H. L.; Afarani, M.; Pierson, W. J.; Cardone, V. J.; Hayes, J.; Spring, W.; Greenwood, C.

    1975-01-01

    The S-193 Radscat made extensive measurements of many sea conditions. Measurements were taken in a tropical hurricane (Ava), a tropical storm (Christine), and in portions of extratropical cyclones. Approximately 200 scans of ocean data at 105 kilometer spacings were taken during the first two Skylab missions and another 200 during the final mission when the characteristics of the measurements changed due to damage of the antenna. Backscatter with four transmit/receive polarization combinations and emissions with horizontal and vertical receive polarizations were measured. Other surface parameters investigated for correlation with the measurements included sea temperature, air/sea temperature difference, and gravity-wave spectrum. Methods were developed to correct the microwave measurements for atmospheric effects. The radiometric data were corrected accurately for clear sky and light cloud conditions only. The radiometer measurements were used to recover the surface scattering characteristics for all atmospheric conditions excluding rain. The radiometer measurements also detected the presence of rain which signaled when the scattering measurement should not be used for surface wind estimation. Regression analysis was used to determine empirically the relation between surface parameters and the microwave measurements, after correction for atmospheric effects. Results indicate a relationship approaching square-law at 50 deg between differential scattering coefficient and wind speed with horizontally polarized scattering data showing slightly more sensitivity to wind speed than vertically polarized data.

  8. Sea surface salinity and temperature seasonal changes in the Solomon and Bismarck Seas

    NASA Astrophysics Data System (ADS)

    Delcroix, Thierry; Radenac, Marie-Helene; Cravatte, Sophie; Gourdeau, Lionel; Alory, Gael

    2014-05-01

    Small SST and SSS (an indicator of iron-rich Papua New Guinea river outflows) changes in the Solomon and Bismarck Seas may be transported to the equatorial Pacific and have strong climatic and biological impacts. We analyze mean and seasonal change of SST and SSS in the Solomon and Bismarck Seas, using 1977-2009 in situ data collected from Voluntary Observing Ships. Co-variability of these two variables with surface wind, altimeter-derived current anomalies, precipitation, and Sepik river discharge is examined. SST and SSS show large annual oscillations in the Solomon Sea, with the coldest and saltiest waters occurring in July/August mainly due to horizontal advection. In contrast, they show large semi-annual oscillations in the Bismarck Sea. There, the coldest and saltiest waters happen in January/February, when the northwest monsoon winds drive coastal upwelling, and in July/August, when the New Guinea Coastal Current advects cold and high-salinity waters from the Solomon Sea through Vitiaz Strait. The low SSS values observed in April/May, stuck between the two SSS maxima, are further enhanced by the Sepik river discharge annual maximum. A high-resolution model strengthens the conclusions we derive from observations. The impacts of ENSO on SST and SSS are also discussed.

  9. Satellite-Derived Sea Surface Temperature: Workshop 1

    NASA Technical Reports Server (NTRS)

    Njoku, E. G.

    1983-01-01

    Satellite measurements of sea surface temperature are now possible using a variety of sensors. The present accuracies of these methods are in the range of 0.5 to 2.0 C. This makes them potentially useful for synoptic studies of ocean currents and for global monitoring of climatological anomalies. To improve confidence in the satellite data, objective evaluations of sensor accuracies are necessary, and the conditions under which these accuracies degrade need to be understood. The Scanning Multichannel Microwave Radiometer (SMMR) on the Nimbus-7 satellite was studied. Sea surface temperatures, derived from November 1979 SMMR data, were compared globally against ship measurements and climatology, using facilities of the JPL Pilot Ocean Data System. Methods for improved data analysis and plans for additional workshops to incorporate data from other sensors were discussed.

  10. Satellite-Derived Sea Surface Temperature: Workshop-2

    NASA Technical Reports Server (NTRS)

    Njoku, E. G.

    1984-01-01

    Global accuracies and error characteristics of presently orbiting satellite sensors are examined. The workshops are intended to lead to a better understanding of present capabilities for sea surface temperature measurement and to improve measurement concepts for the future. Data from the Advanced Very High Resolution Radiometer AVHRR and Scanning Multichannel Microwave Radiometer is emphasized. Some data from the High Resolution Infrared Sounder HIRS and AVHRR are also examined. Comparisons of satellite data with ship and eXpendable BathyThermograph XBT measurement show standard deviations in the range 0.5 to 1.3 C with biases of less than 0.4 C, depending on the sensor, ocean region, and spatial/temporal averaging. The Sea Surface Temperature SST anomaly maps show good agreement in some cases, but a number of sensor related problems are identified.

  11. Japanese Whaling Ships' Sea Surface Temperatures 1946-84.

    NASA Astrophysics Data System (ADS)

    Mierzejewska, Anna W.; Wu, Zhongxiang; Newell, Reginald E.; Miyashita, Tomio

    1997-03-01

    Japanese whaling ship data, a homogeneous dataset mainly covering the southern high-latitude oceans, may be used to fill in gaps in recent sea surface temperature datasets, contributing a fair number of additional observations in this area. The Japanese whaling ship data are treated separately here for the period 1946-84, and they show no significant temperature changes during this period in the main fishing region of 60°-70°S or in the west Pacific warm pool.

  12. The satellite altimeter data derived mean sea surface GSFC98

    NASA Astrophysics Data System (ADS)

    Wang, Yan M.

    2000-03-01

    The GSFC98 mean sea surface (MSS) was computed on a 2' oceanwide grid for latitudes below 80°. The data used included 3-years of TOPEX data (Cycles 9 to 119), 1.5-years of ERS-1 35-day repeat cycle (Cycles 1 to 18), 2-years of Geosat ERM data (Cycles 1 to 42), 2 ERS-1 168-day repeat cycles, and 18 months of the Geosat Geodetic Mission data. All non-TOPEX satellite altimeter data were adjusted to the mean of TOPEX data in 2° × 30° blocks. After the adjustment, the mean sea surface height was gridded into 2' nodes using least squares collocation and an iteration procedure to reduce the ocean variability. To validate the mean sea surfaces, three comparisons were made. The GSFC98 MSS, along with OSU95 [Yi, 1995] and CSR95 [Kim et al., 1995], were compared with 6-years of TOPEX and 3-years of ERS-2 mean tracks which were not used in the MSS computations. Finally, the marine gravity anomalies were computed from the three MSS implied geoid undulations using the inverse Stokes integral. The marine gravity anomalies were compared with ship gravity data in selected areas. The ship gravity comparison is an independent assessment of the quality of the MSSs, especially at intermediate and short wavelengths. Finally, the inter-comparisons between the mean sea surfaces were made. The root mean square values of the differences were 6.8, 6.8, and 7.2 cm between GSFC98/OSU95, GSFC98/CSR95, and OSU95/CSR95. The differences agree well with the error estimation of GSFC98 MSS.

  13. Unravelling air-sea interactions driven by photochemistry in the sea-surface microlayer

    NASA Astrophysics Data System (ADS)

    George, Christian; Alpert, Peter; Tinel, Liselotte; Rossignol, Stéphanie; Perrier, Sébastien; Bernard, Francois; Ciuraru, Raluca; Hayeck, Nathalie

    2016-04-01

    Interfaces are ubiquitous in the environment, and in addition many atmospheric key processes, such as gas deposition, aerosol and cloud formation are, at one stage or the other, strongly impacted by physical- and chemical processes occurring at interfaces. Unfortunately, these processes have only been suggested and discussed but never fully addressed because they were beyond reach. We suggest now that photochemistry or photosensitized reactions exist at interfaces, and we will present and discuss their possible atmospheric implications. Obviously, one of the largest interface is the sea-surface microlayer (SML), which is a region lying at the uppermost tens to hundreds of micrometres of the water surface, with physical, chemical and biological properties that differ from those of the underlying sub-surface water. Organic film formation at the sea surface is made possible in the presence of an excess of surface-active material. Hydrophobic surfactant films are typically believed to play the role of a physical barrier to air-sea exchanges, especially at low wind speed. We will show that dissolved organic matter (DOM) can trigger photochemistry at the air-sea interface, releasing unsaturated, functionalized volatile organic compounds (VOCs), including isoprene,... acting as precursors for the formation of organic aerosols, that were thought, up to now, to be solely of biological origin! In addition, we suggest that when arranged at an air/water interface, hydrophobic surfactant can have weak chemical interactions among them, which can trigger the absorption of sunlight and can consequently induce photochemistry at such interfaces. A major question arises from such observations, namely: can the existence of such weak intra- or intermolecular interactions and the subsequent photochemistry be generalized to many other atmospheric objects such as aerosols? This topic will be presented and discussed.

  14. Kinematics of fluid particles on the sea surface: Hamiltonian theory

    NASA Astrophysics Data System (ADS)

    Fedele, F.; Chandre, C.; Farazmand, M.

    2016-08-01

    We derive the John-Sclavounos equations describing the motion of a fluid particle on the sea surface from first principles using Lagrangian and Hamiltonian formalisms applied to the motion of a frictionless particle constrained on an unsteady surface. The main result is that vorticity generated on a stress-free surface vanishes at a wave crest when the horizontal particle velocity equals the crest propagation speed, which is the kinematic criterion for wave breaking. If this holds for the largest crest, then the symplectic two-form associated with the Hamiltonian dynamics reduces instantaneously to that associated with the motion of a particle in free flight, as if the surface did not exist. Further, exploiting the conservation of the Hamiltonian function for steady surfaces and traveling waves we show that particle velocities remain bounded at all times, ruling out the possibility of the finite-time blowup of solutions.

  15. DNA Stratigraphy reveals Holocene Haptophyte Population Dynamics and Sources of Alkenones at the Species Level

    NASA Astrophysics Data System (ADS)

    Coolen, M. J. L.

    2003-04-01

    Lipid biomarkers provide information on the ancient microbiota of aquatic systems and, hence, can be used to reconstruct the palaeoenvironment. However, these biomarkers are often not very specific. The ultimate biomarkers would be ribosomal RNA (rRNA) genes, which are widely applied in phylogenetic studies. However, it was generally thought that DNA is rapidly degraded soon after burial within sediments. Using advanced molecular biological techniques we showed that DNA of planktonic photosynthetic bacteria and algae as well as zooplankton survived degradation in Holocene anoxic, sulfidic sediments of the permanently stratified, saline Ace Lake (Vestfold Hills, Antarctica). Alkenones were predominant biomarkers in the sediment layers and their source organisms (haptophytes) were identified based on the analysis of fossil 18S rRNA genes. The quantitative comparison of the individual 18S rRNA genes and the various alkenones allowed for the first time the identification of fossil organisms and their biomarkers at the species level. It was shown that all six identified haptophyte phylotypes are closer related to the alkenone-producing haptophyte genus Isochrysis than to the genera Emiliania and Gephyrocapsa. Subtle changes in the alkenone and alkenoate composition correlated with changes in the quantitative phylotype composition of haptophytes. Implications for alkenone stratigraphy will be discussed.

  16. Proteomic analysis of lipid body from the alkenone-producing marine haptophyte alga Tisochrysis lutea.

    PubMed

    Shi, Qing; Araie, Hiroya; Bakku, Ranjith Kumar; Fukao, Yoichiro; Rakwal, Randeep; Suzuki, Iwane; Shiraiwa, Yoshihiro

    2015-12-01

    Lipid body (LB) is recognized as the cellular carbon and energy storage organelle in many organisms. LBs have been observed in the marine haptophyte alga Tisochrysis lutea that produces special lipids such as long-chain (C37 -C40) ketones (alkenones) with 2-4 trans-type double bonds. In this study, we succeeded in developing a modified method to isolate LB from T. lutea. Purity of isolated LBs was confirmed by the absence of chlorophyll auto-fluorescence and no contamination of the most abundant cellular protein ribulose-1,5-bisphosphate carboxylase/oxygenase. As alkenones predominated in the LB by GC-MS analysis, the LB can be more appropriately named as "alkenone body (AB)." Extracted AB-containing proteins were analyzed by the combination of 1DE (SDS-PAGE) and MS/MS for confident protein identification and annotated using BLAST tools at National Center for Biotechnology Information. Totally 514 proteins were identified at the maximum. The homology search identified three major proteins, V-ATPase, a hypothetical protein EMIHUDRAFT_465517 found in other alkenone-producing haptophytes, and a lipid raft-associated SPFH domain-containing protein. Our data suggest that AB of T. lutera is surrounded by a lipid membrane originating from either the ER or the ER-derived four layer-envelopes chloroplast and function as the storage site of alkenones and alkenes.

  17. AIRS Sea Surface Temperature and Pacific Decadal Oscillation

    NASA Astrophysics Data System (ADS)

    Chen, L. L.

    2015-12-01

    Atmospheric Infrared Sounder (AIRS) has been providing necessary measurements for long term atmospheric and surface processes aboard NASA' s Aqua polar orbiter since May 2002. Here, we use time series of AIRS sea surface temperature (SST) anomalies to show the time evolution of Pacific Decadal Oscillation (PDO) in the Gulf of Alaska (lon:-144.5, lat:54.5) from 2003 to 2014. PDO is connected to the first mode of North Pacific SST variability and is tele-connected to ENSO in the tropics. Further analysis of AIRS data can provide clarification of Pacific climate variability.

  18. Middle Pliocene sea surface temperatures: A global reconstruction

    USGS Publications Warehouse

    Dowsett, H.; Barron, J.; Poore, R.

    1996-01-01

    Identification and analyses of Pliocene marine microfossils from 64 globally distributed stratigraphic sequences have been used to produce a middle Pliocene sea surface temperature reconstruction of the Earth. This reconstruction shows little or no change from current conditions in low latitude regions and significant warming of the ocean surface at mid and higher latitudes of both hemispheres. This pattern of warming is consistent with terrestrial records and suggests a combination of enhanced meridional ocean heat transport and enhanced greenhouse effect were responsible for the middle Pliocene warmth.

  19. SMOS sea surface salinity maps of the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Gabarro, Carolina; Olmedo, Estrella; Turiel, Antonio; Ballabrera-Poy, Joaquim; Martinez, Justino; Portabella, Marcos

    2016-04-01

    Salinity and temperature gradients drive the thermohaline circulation of the oceans, and play a key role in the ocean-atmosphere coupling. The strong and direct interactions between the ocean and the cryosphere (primarily through sea ice and ice shelves) is also a key ingredient of the thermohaline circulation. The ESA's Soil Moisture and Ocean Salinity (SMOS) mission, launched in 2009, has the objective measuring soil moisture over the continents and sea surface salinity over the oceans. Although the mission was originally conceived for hydrological and oceanographic studies [1], SMOS is also making inroads in the cryospheric monitoring. SMOS carries an innovative L-band (1.4 GHz, or 21-cm wavelength), passive interferometric radiometer (the so-called MIRAS) that measures the electromagnetic radiation emitted by the Earth's surface, at about 50 km spatial resolution wide swath (1200-km), and with a 3-day revisit time at the equator, but a more frequent one at the poles. Although the SMOS radiometer operating frequency offers almost the maximum sensitivity of the brightness temperature (TB) to sea surface salinity (SSS) variations, this is rather low, , i.e.,: 90% of ocean SSS values span a range of brightness temperatures of only 5K at L-band. This sensitivity is particularly low in cold waters. This implies that the SSS retrieval requires high radiometric performance. Since the SMOS launch, SSS Level 3 maps have been distributed by several expert laboratories including the Barcelona Expert Centre (BEC). However, since the TB sensitivity to SSS decreases with decreasing sea surface temperature (SST), large retrieval errors had been reported when retrieving salinity values at latitudes above 50⁰N. Two new processing algorithms, recently developed at BEC, have led to a considerable improvement of the SMOS data, allowing for the first time to derive SSS maps in cold waters. The first one is to empirically characterize and correct the systematic biases with six

  20. Spatial and temporal variability of satellite-derived sea surface temperature in the Barents Sea

    NASA Astrophysics Data System (ADS)

    Stramska, Malgorzata; Jakowczyk, Mateusz

    2016-04-01

    The Barents Sea (BS) is an important region for studying climate change. This sea is located on the main pathway of the heat transported from low to high latitudes. Since oceanic conditions in the BS may influence vast areas of the Arctic Ocean, it is important to continue to monitor this region and to analyze the available oceanographic data sets. One of the important quantities that can be used to track climate change is the sea surface temperature (SST). In this study we have analyzed the 32-years (1982-2013) NOAA Optimum Interpolation SST Version 2 data for the BS. Our results indicate that the regionally averaged SST trend in the BS (~0.03 oC/year) is greater than the global trend. This trend varies spatially with the lowest values north from 76°N and the highest values (~0.06oC/year) in proximity of Svalbard and in coastal regions near the White Sea. The SST and 2-m air temperature (AT) trends are high in winter months in the open Barents Sea region located west from Novaya Zemlya. Such trends can be linked to a significant retreat of sea ice in this area in recent years. In this paper we also documented spatial patterns in the annual cycle of SST in the BS. We have shown that the interannual variability of SST is similar in different regions of the BS and well correlated with the interannual patterns in AT variability. This work was funded by the Norway Grants (NCBR contract No. 201985, project NORDFLUX). Partial support for MS comes from the Institute of Oceanology (IO PAN).

  1. Long term trend of sea surface temperature in the South China Sea

    NASA Astrophysics Data System (ADS)

    Choi, A.; Park, Y.

    2012-12-01

    Using HAdISST the long term trend in the South China Sea (SCS) sea surface temperature (SST) between 1950 and 2008 is investigated. In general SST has been increased since 1950, but the rate of increase is spatiotemporally uneven. Winter warming rate is greater than that of summer. In both seasons the rate of increase is greater during 1980s. Winter warming rate is greater over the deeper basin while summer warming rate is greater over the shallower southeastern part. In summer the weakening of southwesterly monsoon reduces upwelling along the east coast of Vietnam to warm the surface. On the other hand, the net surface heat flux, however, is reduced and cannot contribute to the warming. In winter the net heat flux into the sea increases and could contribute to the warming. The spatial pattern of the heat flux, however, is different from that of the warming. The heat flux is increased over the coastal area where warming is small, but decreased in deeper part where warming is greater. After 1980's the northeasterly monsoon winds weakens to reduce the southward western boundary currents, and subsequently cold advection and to warm the area.

  2. Ciguatera fish poisoning and sea surface temperatures in the Caribbean Sea and the West Indies.

    PubMed

    Tester, Patricia A; Feldman, Rebecca L; Nau, Amy W; Kibler, Steven R; Wayne Litaker, R

    2010-10-01

    Ciguatera fish poisoning (CFP) is a circumtropical disease caused by ingestion of a variety of reef fish that bioaccumulate algal toxins. Distribution and abundance of the organisms that produce these toxins, chiefly dinoflagellates of the genus Gambierdiscus, are reported to correlate positively with water temperature. Consequently, there is growing concern that increasing temperatures associated with climate change could increase the incidence of CFP. This concern prompted experiments on the growth rates of six Gambierdiscus species at temperatures between 18 degrees C and 33 degrees C and the examination of sea surface temperatures in the Caribbean and West Indies for areas that could sustain rapid Gambierdiscus growth rates year-round. The thermal optimum for five of six Gambierdiscus species tested was >/=29 degrees C. Long-term SST data from the southern Gulf of Mexico indicate the number of days with sea surface temperatures >/=29 degrees C has nearly doubled (44 to 86) in the last three decades. To determine how the sea surface temperatures and Gambierdiscus growth data correlate with CFP incidences in the Caribbean, a literature review and a uniform, region-wide survey (1996-2006) of CFP cases were conducted. The highest CFP incidence rates were in the eastern Caribbean where water temperatures are warmest and least variable.

  3. Chemical characterization of dissolved organic compounds from coastal sea surface microlayers (Baltic Sea, Germany).

    PubMed

    van Pinxteren, Manuela; Müller, Conny; Iinuma, Yoshiteru; Stolle, Christian; Herrmann, Hartmut

    2012-10-01

    The physicochemical properties of the sea surface microlayer (SML), i.e. the boundary layer between the air and the sea, and its impact on air-sea exchange processes have been investigated for decades. However, a detailed description about these processes remains incomplete. In order to obtain a better chemical characterization of the SML, in a case study three pairs of SML and corresponding bulk water samples were taken in the southern Baltic Sea. The samples were analyzed for dissolved organic carbon and dissolved total nitrogen, as well as for several organic nitrogen containing compounds and carbohydrates, namely aliphatic amines, dissolved free amino acids, dissolved free monosaccharides, sugar alcohols, and monosaccharide anhydrates. Therefore, reasonable analytical procedures with respect to desalting and enrichment were established. All aliphatic amines and the majority of the investigated amino acids (11 out of 18) were found in the samples with average concentrations between 53 ng L(-1) and 1574 ng L(-1). The concentrations of carbohydrates were slightly higher, averaging 2900 ng L(-1). Calculation of the enrichment factor (EF) between the sea surface microlayer and the bulk water showed that dissolved total nitrogen was more enriched (EF: 1.1 and 1.2) in the SML than dissolved organic carbon (EF: 1.0 and 1.1). The nitrogen containing organic compounds were generally found to be enriched in the SML (EF: 1.9-9.2), whereas dissolved carbohydrates were not enriched or even depleted (EF: 0.7-1.2). Although the investigated compounds contributed on average only 0.3% to the dissolved organic carbon and 0.4% to the total dissolved nitrogen fraction, these results underline the importance of single compound analysis to determine SML structure, function, and its potential for a transfer of compounds into the atmosphere. PMID:22475414

  4. Organic molecular and carbon isotopic records of the Japan Sea over the past 30 kyr

    NASA Astrophysics Data System (ADS)

    Ishiwatari, R.; Yamada, K.; Matsumoto, K.; Houtatsu, M.; Naraoka, H.

    1999-04-01

    The organic and isotopic geochemical study of two sediment cores (KH-79-3, L-3, and KH-79-3, C-3) from the Oki Ridge in the Japan Sea has revealed that total organic carbon (TOC) mass accumulation rates are extremely high in the 12-11 ka (calendar age) interval and TOC in the sections in the 24-17 ka interval is depleted in 13C by 3.5‰ relative to Holocene sediments. Alkenone sea surface temperature (SST) shows a decrease from 18° to 14°C from 17.5 to 11.6 ka and a sharp increase from 14° to 19°C from 11.6 to 11.1 ka. The SST changes are associated with the inflow of cold seawater with the vertical water mixing and the inflowof warm Tsushima Current into the Japan Sea. The δ13C values for both 24-methylcholesta-5,22-dien-3β-ol (diatom marker) and dinosterol (dinoflagellate marker), are at their minimum from 24 to 17 ka, while those for long-chain alkenones are not. The theoretical considerations on δ13C for biomarkers suggest low photosynthetic carbon demand of diatoms and dinoflagellates from 24 to 17 ka.

  5. The effects of growth phase and salinity on the hydrogen isotopic composition of alkenones produced by coastal haptophyte algae

    NASA Astrophysics Data System (ADS)

    Chivall, David; M'Boule, Daniela; Sinke-Schoen, Daniëlle; Sinninghe Damsté, Jaap S.; Schouten, Stefan; van der Meer, Marcel T. J.

    2014-09-01

    The isotopic fractionation of hydrogen during the biosynthesis of alkenones produced by marine haptophyte algae has been shown to depend on salinity and, as such, the hydrogen isotopic composition of alkenones is emerging as a palaeosalinity proxy. The relationship between fractionation and salinity has previously only been determined during exponential growth, whilst it is not yet known in which growth phases natural haptophyte populations predominantly exist. We have therefore determined the relationship between the fractionation factor, αalkenones-water, and salinity for C37 alkenones produced in different growth phases of batch cultures of the major alkenone-producing coastal haptophytes Isochrysis galbana (strain CCMP 1323) and Chrysotila lamellosa (strain CCMP 1307) over a range in salinity from ca. 10 to 35. αalkenones-water was similar in both species, ranging over 0.841-0.900 for I. galbana and 0.838-0.865 for C. lamellosa. A strong (0.85 ⩽ R2 ⩽ 0.97; p < 0.0001) relationship between salinity and fractionation factor was observed in both species at all growth phases investigated. This suggests that alkenone δD has the potential to be used as a salinity proxy in neritic areas where haptophyte communities are dominated by these coastal species. However, there was a marked difference in the sensitivity of αalkenones-water to salinity between different growth phases: in the exponential growth phase of I. galbana, αalkenones-water increased by 0.0019 per salinity unit (S-1), but was less sensitive at 0.0010 and 0.0008 S-1 during the stationary and decline phases, respectively. Similarly, in C. lamellosa αalkenones-water increased by 0.0010 S-1 in the early stationary phase and by 0.0008 S-1 during the late stationary phase. Assuming the shift in sensitivity of αalkenones-water to salinity observed at the end of exponential growth in I. galbana is similar in other alkenone-producing species, the predominant growth phase of natural populations of

  6. Microwave Imager Measures Sea Surface Temperature Through Clouds

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image was acquired over Tropical Atlantic and U.S. East Coast regions on Aug. 22 - Sept. 23, 1998. Cloud data were collected by the Geostationary Operational Environmental Satellite (GOES). Sea Surface Temperature (SST) data were collected aboard the NASA/NASDA Tropical Rainfall Measuring Mission (TRMM) satellite by The TRMM Microwave Imager (TMI). TMI is the first satellite microwave sensor capable of accurately measuring sea surface temperature through clouds, as shown in this scene. For years scientists have known there is a strong correlation between sea surface temperature and the intensity of hurricanes. But one of the major stumbling blocks for forecasters has been the precise measurement of those temperatures when a storm begins to form. In this scene, clouds have been made translucent to allow an unobstructed view of the surface. Notice Hurricane Bonnie approaching the Carolina Coast (upper left) and Hurricane Danielle following roughly in its path (lower right). The ocean surface has been falsely colored to show a map of water temperature--dark blues are around 75oF, light blues are about 80oF, greens are about 85oF, and yellows are roughly 90oF. A hurricane gathers energy from warm waters found at tropical latitudes. In this image we see Hurricane Bonnie cross the Atlantic, leaving a cooler trail of water in its wake. As Hurricane Danielle followed in Bonnie's path, the wind speed of the second storm dropped markedly, as available energy to fuel the storm dropped off. But when Danielle left Bonnie's wake, wind speeds increased due to temperature increases in surface water around the storm. As a hurricane churns up the ocean, it's central vortex draws surface heat and water into the storm. That suction at the surface causes an upwelling of deep water. At depth, tropical ocean waters are significantly colder than water found near the surface. As they're pulled up to meet the storm, those colder waters essentially leave a footprint in the storm's wake

  7. Seasonal variability of the Red Sea, from GRACE time-variable gravity and altimeter sea surface height measurements

    NASA Astrophysics Data System (ADS)

    Wahr, John; Smeed, David; Leuliette, Eric; Swenson, Sean

    2014-05-01

    Seasonal variability of sea surface height and mass within the Red Sea, occurs mostly through the exchange of heat with the atmosphere and wind-driven inflow and outflow of water through the strait of Bab el Mandab that opens into the Gulf of Aden to the south. The seasonal effects of precipitation and evaporation, of water exchange through the Suez Canal to the north, and of runoff from the adjacent land, are all small. The flow through the Bab el Mandab involves a net mass transfer into the Red Sea during the winter and a net transfer out during the summer. But that flow has a multi-layer pattern, so that in the summer there is actually an influx of cool water at intermediate (~100 m) depths. Thus, summer water in the southern Red Sea is warmer near the surface due to higher air temperatures, but cooler at intermediate depths (especially in the far south). Summer water in the northern Red Sea experiences warming by air-sea exchange only. The temperature profile affects the water density, which impacts the sea surface height but has no effect on vertically integrated mass. Here, we study this seasonal cycle by combining GRACE time-variable mass estimates, altimeter (Jason-1, Jason-2, and Envisat) measurements of sea surface height, and steric sea surface height contributions derived from depth-dependent, climatological values of temperature and salinity obtained from the World Ocean Atlas. We find good consistency, particularly in the northern Red Sea, between these three data types. Among the general characteristics of our results are: (1) the mass contributions to seasonal SSHT variations are much larger than the steric contributions; (2) the mass signal is largest in winter, consistent with winds pushing water into the Red Sea through the Strait of Bab el Mandab in winter, and out during the summer; and (3) the steric signal is largest in summer, consistent with summer sea surface warming.

  8. Sea-surface altimetry airborne observations using synoptic GNSS reflectometry at the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Ribó, Serni; Fabra, Fran; Cardellach, Estel; Li, Weiqiang; Rius, Antonio; Praks, Jaan; Rouhe, Erkka; Seppänen, Jaakko; Martín-Neira, Manuel

    2016-04-01

    Recent GNSS-R (Global Navigation Satellite System-Reflections) observations over the Baltic Sea have been taken using the SPIR (Software PARIS Interferometric Receiver) from an airborne platform at 3 km altitude. This newly developed instrument is capable of acquiring GNSS signals transmitted by multiple satellites simultaneously that have been reflected of the sea-surface. Reflections are usually gathered in off-nadir configuration using the instrument's beam-forming capabilities, which results in an increase of the instrument's swath. In this way, this technique opens the door to densify in space and time sea-altimetry observations to enhance future mesoscale and sub-mesoscale ocean altimetry. The altimetric observations collected during the Baltic Sea campaign have been analysed in terms of their power spectral densities. We consider the sequence of observations as an ergodic process that has contributions from the actual true altimetry as well as the observation noise. In this way it is possible to relate the expected ground resolution of the observations with the obtainable altimetric uncertainty. Results will be presented.

  9. Late Cretaceous (late Campanian-Maastrichtian) sea-surface temperature record of the Boreal Chalk Sea

    NASA Astrophysics Data System (ADS)

    Thibault, Nicolas; Harlou, Rikke; Schovsbo, Niels H.; Stemmerik, Lars; Surlyk, Finn

    2016-02-01

    The last 8 Myr of the Cretaceous greenhouse interval were characterized by a progressive global cooling with superimposed cool/warm fluctuations. The mechanisms responsible for these climatic fluctuations remain a source of debate that can only be resolved through multi-disciplinary studies and better time constraints. For the first time, we present a record of very high-resolution (ca. 4.5 kyr) sea-surface temperature (SST) changes from the Boreal epicontinental Chalk Sea (Stevns-1 core, Denmark), tied to an astronomical timescale of the late Campanian-Maastrichtian (74 to 66 Ma). Well-preserved bulk stable isotope trends and calcareous nannofossil palaeoecological patterns from the fully cored Stevns-1 borehole show marked changes in SSTs. These variations correlate with deep-water records of climate change from the tropical South Atlantic and Pacific oceans but differ greatly from the climate variations of the North Atlantic. We demonstrate that the onset and end of the early Maastrichtian cooling and of the large negative Campanian-Maastrichtian boundary carbon isotope excursion are coincident in the Chalk Sea. The direct link between SSTs and δ13C variations in the Chalk Sea reassesses long-term glacio-eustasy as the potential driver of carbon isotope and climatic variations in the Maastrichtian.

  10. Late Cretaceous (Late Campanian-Maastrichtian) sea surface temperature record of the Boreal Chalk Sea

    NASA Astrophysics Data System (ADS)

    Thibault, N.; Harlou, R.; Schovsbo, N. H.; Stemmerik, L.; Surlyk, F.

    2015-11-01

    The last 8 Myr of the Cretaceous greenhouse interval were characterized by a progressive global cooling with superimposed cool/warm fluctuations. The mechanisms responsible for these climatic fluctuations remain a source of debate that can only be resolved through multi-disciplinary studies and better time constraints. For the first time, we present a record of very high-resolution (ca. 4.5 kyr) sea-surface temperature (SST) changes from the Boreal epicontinental Chalk Sea (Stevns-1 core, Denmark), tied to an astronomical time scale of the late Campanian-Maastrichtian (74 to 66 Myr). Well-preserved bulk stable isotope trends and calcareous nannofossil palaeoecological patterns from the fully cored Stevns-1 borehole show marked changes in SSTs. These variations correlate with deep-water records of climate change from the tropical South Atlantic and Pacific oceans but differ greatly from the climate variations of the North Atlantic. We demonstrate that the onset and end of the early Maastrichtian cooling and of the large negative Campanian-Maastrichtian boundary carbon isotope excursion are coincident in the Chalk Sea. The direct link between SSTs and δ13C variations in the Chalk Sea reassesses long-term glacio-eustasy as the potential driver of carbon isotope and climatic variations in the Maastrichtian.

  11. Modelling impact of bottom roughness on sea surface temperature in the Sea of Iroise

    NASA Astrophysics Data System (ADS)

    Guillou, N.; Chapalain, G.; Duvieilbourg, E.

    2013-02-01

    A hydrological model based on the coupling of the three-dimensional hydrodynamic module COHERENS (COupled Hydrodynamical-Ecological model for RegioNal and Shelf seas) with the wave propagation module SWAN (Simulating WAves Nearshore) is used to study the effects of bottom roughness on sea surface temperature (SST) in the nearshore areas of the Sea of Iroise (western end of french Brittany). Predicted time histories of SST are compared with the available field data collected at two offshore stations and along the route of a vessel travelling between the coast and the isle of Ushant. The comparison is extended to SST spatial distribution derived from remote-sensing observations for conditions characterising the development of horizontal thermal fronts in the Sea of Iroise. A numerical sensitivity study is conducted focusing on the impacts of the heterogeneous bottom roughnesses associated with (i) the granulometric distribution of seabed sediments and (ii) the apparent friction induced by the waves in the bottom boundary layer. Whereas moderate differences are obtained, both bottom-roughness distributions are found to influence the predicted SST leading to slight improvements of global predictions. The sensitivity of numerical simulations is exacerbated in areas of high thermal gradients. The effects of the bottom roughness associated with the seabed are thus revealed at the north-eastern and south-eastern edges of external Ushant thermal front. Waves have a major influence in the nearshore areas of the bay of Audierne and the western extend of Crozon peninsula.

  12. Interannual Trends in Southern Ocean Sea Surface Temperatures and Sea Level from Remote Sensing Data

    NASA Astrophysics Data System (ADS)

    Lebedev, S. A.

    As is shown in last years researches climate changes in Antarctic result in interannual increase trend of surface air temperature and decrease of ice thickness These tendencies are must try in the Southern Ocean hydrological regime For that next remote sensing data AVHRR MCSST data and satellite altimetry data merged data of mission ERS TOPEX Poseidon Jason-1 ENVISAT GFO-1 are used to this task which give information about sea surface temperature SST and sea level anomaly SLA correspondingly According to obtained results SST has positive trend more 0 01 oC yr for 23-yr record 1982-2005 within 300-1000 km northward Antarctic coast However on average for the Southern Ocean SST have negative trend about -0 018 -0 035 oC yr In area of Pacific-Antarctic Ridge and of southern part of Mid Atlantic Ridge decrease rate is more than -0 075 oC yr SLA increases in all area of the Southern Ocean and has average rate about 0 024 -0 026 cm yr for 12-yr record 1993-2005 Around Antarctic SST rate good correspond with the trend analysis of surface air temperature of 8722 0 042 - 0 067oC yr inferred from the satellite 20-yr record Comiso 2000 Nevertheless the observed cooling is intriguing especially since it is compatible with the observed trend in the sea ice cover In the sea ice regions the northernmost positions of the ice edge are shown to be influenced by alternating warm and cold anomalies around the continent This work was partly supported by the Russian Fund of Basic Research Grant 06-05-65061

  13. Sea surface and remotely sensed temperatures off Cape Mendocino, California

    NASA Technical Reports Server (NTRS)

    Breaker, L. C.; Arvesen, J. C.; Frydenlund, D.; Myers, J. S.; Short, K.

    1985-01-01

    During September 3 to 5, 1979, a multisensor oceanographic experiment was conducted off Cape Mendocino, California. The purpose of this experiment was to validate the use of remote sensing techniques over an area along the U.S. west coast where coasted upwelling is known to be intense. Remotely sensed mutlispectral data, including thermal infrared imagery, were collected above an upwelling feature off Cape Mendocino. Data were acquired from the TIRNOS-N and NOAA-6 polar orbiting satellites, the NASA Ames Research Center's high altitude U-2 aircraft, and a U.S. Coast Guard C-130 aircraft. Supporting surface truth data over the same feature were collected aboard the National Oceanic and Atmospheric Administration (NOAA) ship, OCEANOGRAPHER. Atmospheric soundings were also taken aboard the ship. The results indicate that shipboard measurements of sea surface temperatures can be reproduction within 1 C or better through remote observation of absolute infrared radiance values (whether measured aboard the NOAA polar orbiting satellite, the U-2 aircraft, or the Coast Guard aircraft) by using appropriate atmospheric corrections. Also, the patterns of sea surface temperature which were derived independently from the various remote platforms provide a consistent interpretation of the surface temperature field.

  14. Spatial heterogeneity of ocean surface boundary conditions under sea ice

    NASA Astrophysics Data System (ADS)

    Barthélemy, Antoine; Fichefet, Thierry; Goosse, Hugues

    2016-06-01

    The high heterogeneity of sea ice properties implies that its effects on the ocean are spatially variable at horizontal scales as small as a few meters. Previous studies have shown that taking this variability into account in models could be required to simulate adequately mixed layer processes and the upper ocean temperature and salinity structures. Although many advanced sea ice models include a subgrid-scale ice thickness distribution, potentially providing heterogeneous surface boundary conditions, the information is lost in the coupling with a unique ocean grid cell underneath. The present paper provides a thorough examination of boundary conditions at the ocean surface in the NEMO-LIM model, which can be used as a guideline for studies implementing subgrid-scale ocean vertical mixing schemes. Freshwater, salt, solar heat and non-solar heat fluxes are examined, as well as the norm of the surface stress. All of the thermohaline fluxes vary considerably between the open water and ice fractions of grid cells. To a lesser extent, this is also the case for the surface stress. Moreover, the salt fluxes in both hemispheres and the solar heat fluxes in the Arctic show a dependence on the ice thickness category, with more intense fluxes for thinner ice, which promotes further subgrid-scale heterogeneity. Our analysis also points out biases in the simulated open water fraction and in the ice thickness distribution, which should be investigated in more details in order to ensure that the latter is used to the best advantage.

  15. Biological control of surface temperature in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Sathyendranath, Shubha; Gouveia, Albert D.; Shetye, Satish R.; Ravindran, P.; Platt, Trevor

    1991-01-01

    BY far the dominant variable parameter controlling the absorption cross-section for short-wavelength solar radiation incident on the ocean surface is the concentration of photosynthetic pigment contained in phytoplankton cells1,2. The abundance of phytoplankton depends on the intensity of incident radiation and on the supply of essential nutrients (nitrogen in particular). A higher abundance increases absorption of radiation and thus enhances the rate of heating at the ocean surface. In the Arabian Sea, the southwest monsoon promotes seasonal upwelling of deep water, which supplies nutrients to the surface layer3,4 and leads to a marked increase in phytoplankton growth. Using remotely sensed data on ocean colour, we show here that the resulting distribution of phytoplankton exerts a controlling influence on the seasonal evolution of sea surface temperature. This results in a corresponding modification of ocean-atmosphere heat exchange on regional and seasonal scales. Thus we show that this biological mechanism may provide an important regulating influence on ocean-atmosphere interactions.

  16. Passive and active EO sensing close to the sea surface

    NASA Astrophysics Data System (ADS)

    Steinvall, Ove; Persson, Rolf; Berglund, Folke; Öhgren, Johan; Gustafsson, Frank

    2014-10-01

    The present paper investigates the use of an eye-safe laser rangefinder at 1.5 μm and TV/IR imaging to obtain information on atmospheric properties at various paths close to the sea surface. On one day active/passive imaging NIR and SWIR systems were also used. The paper will describe the experimental equipment and the results from measurements of atmospheric backscatter as well as TV and IR images of test targets along a 1.8 km path close to the Baltic Sea. The site also contained a weather station and a scintillometer for logging weather and turbulence parameters. Results correlating the lidar attenuation with the imaging performance will be given and compared with models.

  17. Sea surface temperature contributes to marine crocodylomorph evolution.

    PubMed

    Martin, Jeremy E; Amiot, Romain; Lécuyer, Christophe; Benton, Michael J

    2014-01-01

    During the Mesozoic and Cenozoic, four distinct crocodylomorph lineages colonized the marine environment. They were conspicuously absent from high latitudes, which in the Mesozoic were occupied by warm-blooded ichthyosaurs and plesiosaurs. Despite a relatively well-constrained stratigraphic distribution, the varying diversities of marine crocodylomorphs are poorly understood, because their extinctions neither coincided with any major biological crises nor with the advent of potential competitors. Here we test the potential link between their evolutionary history in terms of taxic diversity and two abiotic factors, sea level variations and sea surface temperatures (SST). Excluding Metriorhynchoidea, which may have had a peculiar ecology, significant correlations obtained between generic diversity and estimated Tethyan SST suggest that water temperature was a driver of marine crocodylomorph diversity. Being most probably ectothermic reptiles, these lineages colonized the marine realm and diversified during warm periods, then declined or became extinct during cold intervals. PMID:25130564

  18. Multisensor monitoring of sea surface state of the coastal zone

    NASA Astrophysics Data System (ADS)

    Lavrova, Olga; Mityagina, Marina; Bocharova, Tatina

    Results of many-year monitoring of the state of coastal zone based on a multisensor approach are presented. The monitoring is aimed at solving the following tasks: operational mapping of parameters characterizing the state and pollution (coastal, ship and biogenic) of water; analysis of meteorological state and its effect on the drift and spread of pollutants; study of coastal circulation patterns and their impact on the drift and spread of pollutants; deriving typical pollution distribution patterns in the coastal zone.Processing and analysis is performed using data in visual, infrared and microwave ranges from ERS-2 SAR, Envisat ASAR/MERIS, Terra and Aqua MODIS and NOAA AVHRR instruments. These are complimented with ground data from meteorological stations on the shore and results of satellite data processing of previous periods. The main regions of interest are the Russian sectors of the Black and Azov Seas, southeastern part of the Baltic Sea, and northern and central regions of the Caspian Sea. Adjacent coasts are extremely populated and have well-developed industry, agriculture and rapidly growing tourist sectors. The necessity of constant monitoring of the sea state there is obvious.The monitoring activities allow us to accumulate extensive material for the study of hydrodynamic processes in the regions, in particular water circulation. Detailing the occurrence, evolution and drift of smalland meso-scale vortex structures is crucial for the knowledge of the mechanisms determining mixing and circulation processes in the coastal zone. These mechanisms play an important role in ecological, hydrodynamic and meteorological status of a coastal zone. Special attention is paid to the sea surface state in the Kerch Strait, where a tanker catastrophe took place on November 11, 2007 causing a spillage of over 1.5 thousand tons of heavy oil. The Kerch Strait is characterized by a complex current system with current directions changing to their opposites depending on

  19. Microwave Remote Sensing Modeling of Ocean Surface Salinity and Winds Using an Empirical Sea Surface Spectrum

    NASA Technical Reports Server (NTRS)

    Yueh, Simon H.

    2004-01-01

    Active and passive microwave remote sensing techniques have been investigated for the remote sensing of ocean surface wind and salinity. We revised an ocean surface spectrum using the CMOD-5 geophysical model function (GMF) for the European Remote Sensing (ERS) C-band scatterometer and the Ku-band GMF for the NASA SeaWinds scatterometer. The predictions of microwave brightness temperatures from this model agree well with satellite, aircraft and tower-based microwave radiometer data. This suggests that the impact of surface roughness on microwave brightness temperatures and radar scattering coefficients of sea surfaces can be consistently characterized by a roughness spectrum, providing physical basis for using combined active and passive remote sensing techniques for ocean surface wind and salinity remote sensing.

  20. Modern Tasman Sea surface reservoir ages from deep-sea black corals

    NASA Astrophysics Data System (ADS)

    Komugabe, Aimée F.; Fallon, Stewart J.; Thresher, Ronald E.; Eggins, Stephen M.

    2014-01-01

    Marine reservoir ages are a key element in calculating and constraining uncertainty in radiocarbon age estimates and are also essential to better understand regional ocean circulation. In this study, we present a new method to reconstruct long-term, high-resolution sea surface reservoir ages based on analysis of the organic skeleton of deep-sea (560 m) black coral (Anthozoa, Antipatharia). Our results confirm that antipatharians are extremely slow growing (typical radial growth rate for a South Pacific specimen around 0.03 mm/yr). Coupled uranium series and radiocarbon measurements were made on black coral collected live from the Norfolk Ridge (north Tasman Sea) to provide the first modern reservoir ages for this region. At the Norfolk Ridge, the average reservoir age between 1790 AD and 1900 AD was ∼330 years. This was followed by a steep decrease over time of about 70 years to 1950 AD (our most modern value). This indicates an increase in surface ocean ventilation of water masses in this region. These results are consistent with observational studies for the early twentieth century, which suggest significant changes in regional circulation of the southwest pacific.

  1. A paleoenvironmental reconstruction of the last 15 000 cal yr BP via Yellow Sea sediments using biomarkers and isotopic composition of organic matter

    NASA Astrophysics Data System (ADS)

    Badejo, A. O.; Choi, B.-H.; Cho, H.-G.; Yi, H.-I.; Shin, K.-H.

    2014-04-01

    This study is the first reconstruction of the paleoenvironment and paleovegetation during the Holocene (interglacial) and glacial periods of the Yellow Sea. We report the carbon isotopic and biomarker (n-alkane and alkenone) compositions of organic matter from Yellow Sea sediments since the glacial period. Our findings show that the variability of the East Asian Monsoon (EAM) affected the sedimentary profile of total organic carbon (TOC), the stable isotopes of bulk organic carbon (δ13Corg), the atomic ratio of carbon and nitrogen (C/N ratio), and biomarker content. The sedimentary δ13Corg profile along the core exhibited more negative δ13Corg values under cold/dry climatic conditions (Younger and Oldest Dryas). The carbon preference index (CPI), the pristane to phytane ratio (Pr/Ph) and the pristane to n-C17 ratio (Pr/n-C17) were used to determine the early stages of diagenesis along the sediment core. Two climatic conditions were distinguished (warm/humid and cold/dry) based on an n-alkane proxy, and the observed changes in δ13C of individual n-alkane (δ13CALK) between the Holocene and glacial periods were attributed to changes in plant distribution/type. Clear differences were not found in the calculated alkenone sea surface temperature (SST) between those of the Holocene and glacial periods. This anomaly during the glacial period might be attributed to the seasonal water mass distribution in the Yellow Sea or a seasonal shift in the timing of maximum alkenone production as well as the Bølling/Allerød interstadial.

  2. Retrieval of eddy dynamics from SMOS sea surface salinity measurements in the Algerian Basin (Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    The circulation in the Algerian Basin is characterized by the presence of fresh-core eddies that propagate along the coast or at distances between 100 and 200 km from the coast. Enhancements in the processing of the Soil Moisture and Ocean Salinity (SMOS) data have allowed to produce, for the first time, satellite sea surface salinity (SSS) maps in the Mediterranean Sea that capture the signature of Algerian eddies. SMOS data can be used to track them for long periods of time, especially during winter. SMOS SSS maps are well correlated with in situ measurements although the former has a smaller dynamical range. Despite this limitation, SMOS SSS maps capture the key dynamics of Algerian eddies allowing to retrieve velocities from SSS with the correct sign of vorticity.

  3. Responses of atmospheric circulation to sea surface temperature anomalies in the South China Sea

    NASA Astrophysics Data System (ADS)

    Zhou, M. P.; Wang, G. H.

    2015-11-01

    The sea surface temperature (SST) anomalies in the South China Sea (SCS) and their influences on global atmospheric circulation were studied. The results of a simple atmospheric model suggested that the SCS SST anomalies can induce several barotropic wave trains from the SCS to other regions such as North America, high latitudes of the Southern Hemisphere and the Mediterranean. The baroclinic stream function anomalies from the simple model showed an anticyclonic vortex pair in the Asian continent and the northern and southern Indian Ocean and a cyclonic vortex in the North Pacific and the southwestern Pacific. It is suggested that the spatial pattern of SST anomalies in the SCS can affect the magnitude of stream function anomalies, although it cannot affect the spatial pattern of atmospheric circulation.

  4. Estimation of subsurface thermal structure using sea surface height and sea surface temperature

    NASA Technical Reports Server (NTRS)

    Kang, Yong Q. (Inventor); Jo, Young-Heon (Inventor); Yan, Xiao-Hai (Inventor)

    2012-01-01

    A method of determining a subsurface temperature in a body of water is disclosed. The method includes obtaining surface temperature anomaly data and surface height anomaly data of the body of water for a region of interest, and also obtaining subsurface temperature anomaly data for the region of interest at a plurality of depths. The method further includes regressing the obtained surface temperature anomaly data and surface height anomaly data for the region of interest with the obtained subsurface temperature anomaly data for the plurality of depths to generate regression coefficients, estimating a subsurface temperature at one or more other depths for the region of interest based on the generated regression coefficients and outputting the estimated subsurface temperature at the one or more other depths. Using the estimated subsurface temperature, signal propagation times and trajectories of marine life in the body of water are determined.

  5. Simulations of The Extreme Precipitation Event Enhanced by Sea Surface Temperature Anomaly over the Black Sea

    NASA Astrophysics Data System (ADS)

    Hakan Doǧan, Onur; Önol, Barış

    2016-04-01

    Istanbul Technical University, Aeronautics and Astronautics Faculty, Meteorological Engineering, Istanbul, Turkey In this study, we examined the extreme precipitation case over the Eastern Black Sea region of Turkey by using regional climate model, RegCM4. The flood caused by excessive rain in August 26, 2010 killed 12 people and the landslides in Rize province have damaged many buildings. The station based two days total precipitation exceeds 200 mm. One of the usual suspects for this extreme event is positive anomaly of sea surface temperature (SST) over the Black Sea where the significant warming trend is clear in the last three decades. In August 2010, the monthly mean SST is higher than 3 °C with respect to the period of 1981-2010. We designed three sensitivity simulations with RegCM4 to define the effects of the Black Sea as a moisture source. The simulation domain with 10-km horizontal resolution covers all the countries bordering the Black Sea and simulation period is defined for entire August 2010. It is also noted that the spatial variability of the precipitation produced by the reference simulation (Sim-0) is consistent with the TRMM data. In terms of analysis of the sensitivity to SST, we forced the simulations by subtracting 1 °C (Sim-1), 2 °C (Sim-2) and 3 °C (Sim-3) from the ERA-Interim 6-hourly SST data (considering only the Black Sea). The sensitivity simulations indicate that daily total precipitation for all these simulations gradually decreased based on the reference simulation (Sim-0). 3-hourly maximum precipitation rates for Sim-0, Sim-1, Sim-2 and Sim-3 are 32, 25, 13 and 10.5 mm respectively over the hotspot region. Despite the fact that the simulations signal points out the same direction, degradation of the precipitation intensity does not indicate the same magnitude for all simulations. It is revealed that 2 °C (Sim-2) threshold is critical for SST sensitivity. We also calculated the humidity differences from the simulation and these

  6. Surface Heat Budgets and Sea Surface Temperature in the Pacific Warm Pool During TOGA COARE

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Zhao, Wenzhong; Chou, Ming-Dah

    1998-01-01

    The daily mean heat and momentum fluxes at the surface derived from the SSM/I and Japan's GMS radiance measurements are used to study the temporal and spatial variability of the surface energy budgets and their relationship to the sea surface temperature during the COARE intensive observing period (IOP). For the three time legs observed during the IOP, the retrieved surface fluxes compare reasonably well with those from the IMET buoy, RV Moana Wave, and RV Wecoma. The characteristics of surface heat and momentum fluxes are very different between the southern and northern warm pool. In the southern warm pool, the net surface heat flux is dominated by solar radiation which is, in turn, modulated by the two Madden-Julian oscillations. The surface winds are generally weak, leading to a shallow ocean mixed layer. The solar radiation penetrating through the bottom of the mixed layer is significant, and the change in the sea surface temperature during the IOP does not follow the net surface heat flux. In the northern warm pool, the northeasterly trade wind is strong and undergoes strong seasonal variation. The variation of the net surface heat flux is dominated by evaporation. The two westerly wind bursts associated with the Madden-Julian oscillations seem to have little effect on the net surface heat flux. The ocean mixed layer is deep, and the solar radiation penetrating through the bottom of the mixed layer is small. As opposed to the southern warm pool, the trend of the sea surface temperature in the northern warm pool during the IOP is in agreement with the variation of the net heat flux at the surface.

  7. Joint variability of global runoff and global sea surface temperatures

    USGS Publications Warehouse

    McCabe, G.J.; Wolock, D.M.

    2008-01-01

    Global land surface runoff and sea surface temperatures (SST) are analyzed to identify the primary modes of variability of these hydroclimatic data for the period 1905-2002. A monthly water-balance model first is used with global monthly temperature and precipitation data to compute time series of annual gridded runoff for the analysis period. The annual runoff time series data are combined with gridded annual sea surface temperature data, and the combined dataset is subjected to a principal components analysis (PCA) to identify the primary modes of variability. The first three components from the PCA explain 29% of the total variability in the combined runoff/SST dataset. The first component explains 15% of the total variance and primarily represents long-term trends in the data. The long-term trends in SSTs are evident as warming in all of the oceans. The associated long-term trends in runoff suggest increasing flows for parts of North America, South America, Eurasia, and Australia; decreasing runoff is most notable in western Africa. The second principal component explains 9% of the total variance and reflects variability of the El Ni??o-Southern Oscillation (ENSO) and its associated influence on global annual runoff patterns. The third component explains 5% of the total variance and indicates a response of global annual runoff to variability in North Aflantic SSTs. The association between runoff and North Atlantic SSTs may explain an apparent steplike change in runoff that occurred around 1970 for a number of continental regions.

  8. Ocean backscatter across the Gulf Stream sea surface temperature front

    SciTech Connect

    Nghiem, S.V.; Li, F.K.

    1997-06-01

    Ocean backscatter was measured by the Jet Propulsion Laboratory, with the airborne NUSCAT K{sub u}-band scatterometer, across the Gulf Stream sea surface temperature front during the Surface Wave Dynamics Experiment off the coast of Virginia and Maryland in the winter of 1991. Backscatter across the front between the National Oceanic and Atmospheric Administration experimental coastal buoy A (44024) on the cold side and Discus C buoy (44023) on the warm side shows a difference of more than 5 dB for vertical polarization in many cases. This large frontal backscatter change is observed in all upwind, downwind, and crosswind directions. The sea surface temperature difference measured by the buoys was about 9{degrees}C. The corresponding difference in wind speed cannot account for the large backscatter change in view of geophysical model functions depending only on neutral wind velocity such as SASS. The measured backscatter also has larger upwind-downwind and upwind-crosswind ratios compared to the model results. Furthermore, NUSCAT data reveal that upwind backscatter on the cold side was smaller than or close to crosswind backscatter on the warm side for incidence angles between 30{degrees} to 50{degrees}. This suggests that the temperature front can be detected by the scatterometer at these incidence angles for different wind directions in the cold and warm sides.

  9. Pacific sea level rise patterns and global surface temperature variability

    NASA Astrophysics Data System (ADS)

    Peyser, Cheryl E.; Yin, Jianjun; Landerer, Felix W.; Cole, Julia E.

    2016-08-01

    During 1998-2012, climate change and sea level rise (SLR) exhibit two notable features: a slowdown of global surface warming (hiatus) and a rapid SLR in the tropical western Pacific. To quantify their relationship, we analyze the long-term control simulations of 38 climate models. We find a significant and robust correlation between the east-west contrast of dynamic sea level (DSL) in the Pacific and global mean surface temperature (GST) variability on both interannual and decadal time scales. Based on linear regression of the multimodel ensemble mean, the anomalously fast SLR in the western tropical Pacific observed during 1998-2012 indicates suppression of a potential global surface warming of 0.16° ± 0.06°C. In contrast, the Pacific contributed 0.29° ± 0.10°C to the significant interannual GST increase in 1997/1998. The Pacific DSL anomalies observed in 2015 suggest that the strong El Niño in 2015/2016 could lead to a 0.21° ± 0.07°C GST jump.

  10. Radio emission of sea surface at centimeter wavelengths and is fluctuations

    NASA Technical Reports Server (NTRS)

    Tseytlin, N. M.; Shutko, A. M.; Zhislin, G. M.

    1981-01-01

    The eigen thermal radio emission of the sea was examined as well as the agitated surface of the sea when the reflection (scattering) is similar in nature to diffused scattering. The contribution of this emission to the total emission of the sea is practically constant in time, and the time fluctuations of the radio emissions of the sea are basically determined only by a change in the eigen emission of the sea, connected with the agitation.

  11. A multispectral method of measuring sea surface temperatures from satellites

    NASA Technical Reports Server (NTRS)

    Shenk, W. E.; Salomonson, V. V.

    1972-01-01

    A multispectral technique has been developed which independently tests for the presence of clouds before a registered window radiance measurement is accepted as coming from the sea surface and the intervening atmosphere. The spatial resolution of ocean temperature mapping can be the same as that of the radiometer. With the 55 km subsatellite track resolution of the Nimbus 2 MRIR, current boundaries and upwelling areas have been successfully identified. Knowledge of the position of these regions and temperatures within them are important to the detection of areas of high chlorophyll concentrations.

  12. Spherical harmonic expansion of the Levitus Sea surface topography

    NASA Technical Reports Server (NTRS)

    Engelis, Theodossios

    1987-01-01

    Prior information for the stationary sea surface topography (SST) may be needed in altimetric solutions that intend to simultaneously improve the gravity field and determine the SST. For this purpose the oceanographically derived SST estimates are represented by a spherical harmonic expansion. The spherical harmonic coefficients are computed from a least squares adjustment of the data covering the majority of the oceanic regions of the world. Several tests are made to determine the optimum maximum degree of solution and the best configuration of the geometry of the data in order to obtain a solution that fits the data and also provides a good spectral representation of the SST.

  13. Sea Surface Temperature and Vegetation Index from MODIS

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is a composite MODIS image showing the 'green wave' of spring in North America and sea surface temperature in the ocean, collected over an 8-day period during the first week in April 2000. On land, the darker green pixels show where the most green foliage is being produced due to photosynthetic activity. Yellows on land show where there is little or no productivity and red is a boundary zone. In the ocean, orange and yellows show warmer waters and blues show colder values. (MODIS Data Type: MODIS-PFM)

  14. Alkenone δD as an ecological indicator: A culture and field study of physiologically-controlled chemical and hydrogen-isotopic variation in C37 alkenones

    NASA Astrophysics Data System (ADS)

    Wolhowe, Matthew D.; Prahl, Fredrick G.; Langer, Gerald; Oviedo, Angela Maria; Ziveri, Patrizia

    2015-08-01

    A combined culture and field study was conducted in order to (1) more firmly identify the physiological controls on hydrogen isotopic composition of C37 alkenones produced by open-ocean coccolithophores and (2) determine the degree to which these controls are manifested in a natural water column. Nutrient-limitation experiments in culture, combined with previously published data, show that net fractionation between the growth medium and alkenones (αK37) varies with cellular alkenone content and production rate, and, by extension, growth phase. It is hypothesized that the relationship of αK37 with cellular alkenone content and production rate is due to increased use of anabolic NADPH in response to high rates of lipid synthesis. Euphotic zone profiles of δDK37, measured in suspended material from the Gulf of California and Eastern Tropical North Pacific, decreased with depth and light availability, and did not correlate in any expected way with previously-suggested controls on αK37. It is possible that the field data are driven by behavior in light-limited cells that is not represented by the available, nutrient-limited culture data. If true, δDK37 may have utility as an indicator of production depth in settings prone to subsurface production maxima. Relationships between αK37, cell density, and the carbon-isotopic fractionation term εp, however, suggest that αK37 acts an indicator of growth rate, which in this setting is only partially dependent on light, consistent with our interpretation of the culture data. If this latter interpretation proves correct, δDK37 may be a powerful ecological proxy specific to these climatically-important, calcifying, temperature-encoding species.

  15. The influence of global sea surface temperature variability on the large-scale land surface temperature

    NASA Astrophysics Data System (ADS)

    Tyrrell, Nicholas L.; Dommenget, Dietmar; Frauen, Claudia; Wales, Scott; Rezny, Mike

    2015-04-01

    In global warming scenarios, global land surface temperatures () warm with greater amplitude than sea surface temperatures (SSTs), leading to a land/sea warming contrast even in equilibrium. Similarly, the interannual variability of is larger than the covariant interannual SST variability, leading to a land/sea contrast in natural variability. This work investigates the land/sea contrast in natural variability based on global observations, coupled general circulation model simulations and idealised atmospheric general circulation model simulations with different SST forcings. The land/sea temperature contrast in interannual variability is found to exist in observations and models to a varying extent in global, tropical and extra-tropical bands. There is agreement between models and observations in the tropics but not the extra-tropics. Causality in the land-sea relationship is explored with modelling experiments forced with prescribed SSTs, where an amplification of the imposed SST variability is seen over land. The amplification of to tropical SST anomalies is due to the enhanced upper level atmospheric warming that corresponds with tropical moist convection over oceans leading to upper level temperature variations that are larger in amplitude than the source SST anomalies. This mechanism is similar to that proposed for explaining the equilibrium global warming land/sea warming contrast. The link of the to the dominant mode of tropical and global interannual climate variability, the El Niño Southern Oscillation (ENSO), is found to be an indirect and delayed connection. ENSO SST variability affects the oceans outside the tropical Pacific, which in turn leads to a further, amplified and delayed response of.

  16. Sea surface Ka-band radar cross-section from field observations in the Black Sea

    NASA Astrophysics Data System (ADS)

    Yurovsky, Yury; Kudryavtsev, Vladimir; Grodsky, Semyon; Chapron, Bertrand

    2016-04-01

    An interest in Ka-band radar backscattering from the ocean surface is growing due to better spatial resolution and more accurate Doppler anomaly estimate. But, available empirical models of Ka-band cross-section are quite scarce and sometime controversial. Here we present multi-year (2009-2015) field measurements of Ka-band co-polarized (VV and HH) sea surface normalized radar cross-section (NRCS) from research platform in the Black sea collected in a wide range of observation and sea state conditions. The data are fitted by polynomial function of incidence angle, azimuth and wind speed with accounting for measured radar antenna pattern. This empirical NRCS is compared with published Ka- and Ku-band data. Our Ka-band NRCS is close to Ku-band, but is 5-7 dB higher than 'pioneer' measurements by Masuko et al. (1986). Following the two-scale Bragg paradigm, the NRCS is split into polarized (Bragg) and non-polarized components and analyzed in terms of polarization ratio (VV/HH) and polarization difference (VV-HH) to estimate wave spectra at the Bragg wave number. Non-polarized component dominates at low incidence angles <30° due to specular reflection from regular surface. At larger incidence angles, the relative non-polarized contribution decreases, but grows again at HH-polarization approaching 0.7-0.8 at 65° for 10 m/s wind speed, suggesting that backscattering from breaking waves dominates HH NRCS at low grazing angles. At high incidence angles (>60°) NRCS azimuth dependency is unimodal (upwind peak) for HH and bimodal (with up- and downwind peaks) for VV polarization. This again can be attributed to different backscattering mechanisms for VV and HH polarizations. With decreasing of incidence angle, up- to downwind ratio tends to 1, and under light wind conditions (4-6 m/s) can be less than 1. The same situation is observed for polarization difference, which reflects Bragg backscattering properties only. This effect can be explained by enhanced roughness on

  17. A high-resolution global sea surface temperature climatology

    SciTech Connect

    Reynolds, R.W.; Smith, T.M.

    1995-06-01

    In response to the development of a new higher-resolution sea surface temperature (SST) analysis at the National Meteorological Center (NMC), a new monthly 1{degrees} global sea surface temperature climatology was constructed from two intermediate climatologies: the 2{degrees} SST climatology used a 30-yr 1950-1979 base period between roughly 40{degrees}S and 60{degrees}N based on in situ (ship and buoy) SST data supplemented by four years (1982-1985) of satellite SST retrievals, and sea-ice coverage data over a 12-yr period (1982-1993). The final climatology was combined from these two products so that a 1{degrees} resolution was maintained and the base period was adjusted to the 1950-1979 period wherever possible (approximately between 40{degrees}S and 60{degrees}N). Compared to the 2{degrees} climatology, the 1{degrees} climatology resolves equatorial upwelling and fronts much better. This leads to a better matching of the scales of the new analysis and climatology. In addition, because the magnitudes of large-scale features are consistently maintained in both the older 2{degrees} and the new 1{degrees} climatologies, climate monitoring of large-scale anomalies will be minimally affected by the analysis change. The use of 12 years of satellite SST retrievals makes this new climatology useful for many additional purposes because its effective resolution actually approaches 1{degrees} everywhere over the global ocean and because the mean SST values are more accurate south of 40{degrees}S than climatologies without these data. 12 refs., 16 figs.

  18. Attributing extreme precipitation in the Black Sea region to sea surface warming

    NASA Astrophysics Data System (ADS)

    Meredith, Edmund; Semenov, Vladimir; Maraun, Douglas; Park, Wonsun; Chernokulsky, Alexander

    2016-04-01

    Higher sea surface temperatures (SSTs) warm and moisten the overlying atmosphere, increasing the low-level atmospheric instability, the moisture available to precipitating systems and, hence, the potential for intense convective systems. Both the Mediterranean and Black Sea regions have seen a steady increase in summertime SSTs since the early 1980s, by over 2 K in places. This raises the question of how this SST increase has affected convective precipitation extremes in the region, and through which mechanisms any effects are manifested. In particular, the Black Sea town of Krymsk suffered an unprecedented precipitation extreme in July 2012, which may have been influenced by Black Sea warming, causing over 170 deaths. To address this question, we adopt two distinct modelling approaches to event attribution and compare their relative merits. In the first, we use the traditional probabilistic event attribution approach involving global climate model ensembles representative of the present and a counterfactual past climate where regional SSTs have not increased. In the second, we use the conditional event attribution approach, taking the 2012 Krymsk precipitation extreme as a showcase example. Under the second approach, we carry out ensemble sensitivity experiments of the Krymsk event at convection-permitting resolution with the WRF regional model, and test the sensitivity of the event to a range of SST forcings. Both experiments show the crucial role of recent Black Sea warming in amplifying the 2012 Krymsk precipitation extreme. In the conditional event attribution approach, though, the explicit simulation of convective processes provides detailed insight into the physical mechanisms behind the extremeness of the event, revealing the dominant role of dynamical (i.e. static stability and vertical motions) over thermodynamical (i.e. increased atmospheric moisture) changes. Additionally, the wide range of SST states tested in the regional setup, which would be

  19. Chlorinated hydrocarbons in the Sargasso sea atmosphere and surface water.

    PubMed

    Bidleman, T F; Olney, C E

    1974-02-01

    Polychlorinated biphenyls (PCB), DDT, and chlordane concentrations were measured in air sampled from a tower on the south shore of Bermuda and in Sargasso Sea surface water approximately 80 to 320 kilometers south of Bermuda. The atmospheric chlorinated hydrocarbons appeared to be gaseous, and the DDT concentration was two orders of magnitude higher than previously reported particulate values. The PCB and DDT were enriched in the surface microlayer (150 micrometers) relative to their concentrations in water at a depth of 30 centimeters. Atmospheric residence times for PCB and DDT of 40 to 50 days, calculated from the concentrations in the air and water, are 20 times shorter than values previously estimated for DDT from rainfall and DDT production data.

  20. Satellite measurements of sea surface temperature through clouds

    PubMed

    Wentz; Gentemann; Smith; Chelton

    2000-05-01

    Measurements of sea surface temperature (SST) can be made by satellite microwave radiometry in all weather conditions except rain. Microwaves penetrate clouds with little attenuation, giving an uninterrupted view of the ocean surface. This is a distinct advantage over infrared measurements of SST, which are obstructed by clouds. Comparisons with ocean buoys show a root mean square difference of about 0.6 degrees C, which is partly due to the satellite-buoy spatial-temporal sampling mismatch and the difference between the ocean skin temperature and bulk temperature. Microwave SST retrievals provide insights in a number of areas, including tropical instability waves, marine boundary layer dynamics, and the prediction of hurricane intensity.

  1. Emerita analoga recruit populations and correlations with sea surface temperature

    NASA Astrophysics Data System (ADS)

    Pettway, J.; Quan, H.; Juarez, F.; Vicencio, M.; Ng, N.; Careers in Science Intern Program

    2010-12-01

    The Careers in Science program at the California Academy of Sciences is a science internship for students from groups traditionally under-represented in the sciences. Starting in 2003, interns have participated in the Farallones Marine Sanctuary Association's LiMPETS Sandy Beach Monitoring program, assessing populations of Emerita analoga, the Pacific mole crab. E. analoga, an inhabitant of intertidal swash zones along the coast from Alaska to Baja California, is an important species in the sandy beach intertidal food web. Weekly, during the months of June, July and August, a group of interns go to stairwell 18 of San Francisco’s Ocean Beach in Golden Gate National Recreational Area to systematically collect live E. analoga samples and data. Along a 50 meter sampling area, five transects with ten samples in the swash zone are taken and recorded. Collected E. analoga are sexed (male, female, female w/eggs, and recruit) and measured for carapace size. Newly settled E. analoga (recruit) populations have declined in recent years. However, beginning in 2009, recruit populations began to increase in number, particularly in 2010. Our group hypothesized that this increase in recruitment is correlated with increased sea surface temperature. It has been reported that some planktonic animals become more abundant in warmer waters after a major temperature shift. After examining the data, we did not find a correlation between sea surface temperature and recruit populations, leading us to further questions on the cause of this increase in E. analoga recruits.

  2. Sea surface temperature and short term climate predictability

    NASA Astrophysics Data System (ADS)

    Andronache, Constantin

    2013-03-01

    Atmospheric processes have a relatively short memory of initial conditions of about two weeks for detailed daily weather prediction. Nevertheless, skilful seasonal forecast is possible in the presence of slow varying boundary conditions (BC) of the atmosphere, such as sea surface temperature anomalies (SSTA) over large oceanic regions. These conditions typically evolve on a much slower time scale than daily weather events and atmospheric predictability can be increased as long as the future evolution of such BC can be predicted. Given the importance of SSTA in the interaction between the ocean and atmosphere, it is of interest to investigate the nature of temporal persistence of large-scale SSTA in the global ocean. We use the global SSTA and investigate possible sources of predictability at seasonal time scale and its impact in various regions of the ocean. Data used are the NOAA Extended Reconstructed Sea Surface Temperature (SST). We show that: 1) SSTA has a persistence that depends largely on regional location in the global ocean; 2) A given SSTA distribution from a particular month, can have corresponding similar configurations in the past, largely due to the recurrence of ENSO events which affect SSTA distribution over vast regions of the global ocean.

  3. Temporal and spatial variations of sea surface temperature in the East China Sea

    NASA Astrophysics Data System (ADS)

    Tseng, Chente; Lin, Chiyuan; Chen, Shihchin; Shyu, Chungzen

    2000-03-01

    Sea surface temperature of the East China Sea (ECS) were analyzed using the NOAA/AVHRR SST images. These satellite images reveal surface features of ECS including mainly the Kuroshio Current, Kuroshio Branch Current, Taiwan Warm Current, China coastal water, Changjiang diluted water and Yellow Sea mixed cold water. The SST of ECS ranges from 27 to 29°C in summer; some cold eddies were found off northeast Taiwan and to the south of Changjiang mouth. SST anomalies at the center of these eddies were about 2-5°C. The strongest front usually occurs in May each year and its temperature gradient is about 5-6°C over a cross-shelf distance of 30 nautical miles. The Yellow Sea mixed cold water also provides a contrast from China Coastal waters shoreward of the 50 m isobath; cross-shore temperature gradient is about 6-8°C over 30 nautical miles. The Kuroshio intrudes into ECS preferably at two locations. The first is off northeast Taiwan; the subsurface water of Kuroshio is upwelled onto the shelf while the main current is deflected seaward. The second site is located at 31°N and 128°E, which is generally considered as the origin of the Tsushima Warm Current. More quantitatively, a 2-year time series of monthly SST images is examined using EOF analysis to determine the spatial and temporal variations in the northwestern portion of ECS. The first spatial EOF mode accounts for 47.4% of total spatial variance and reveals the Changjiang plume and coastal cold waters off China. The second and third EOF modes account for 16.4 and 9.6% of total variance, respectively, and their eigenvector images show the intrusion of Yellow Sea mixed cold waters and the China coastal water. The fourth EOF mode accounts for 5.4% of total variance and reveals cold eddies around Chusan Islands. The temporal variance EOF analysis is less revealing in this study area.

  4. Beyond fatty acid methyl esters: Expanding the renewable carbon profile with alkenones from Isochrysis sp.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In addition to characteristic fatty acid methyl esters (FAMEs), biodiesel produced from Isochrysis sp. contains a significant amount (14% dry weight) of predominantly C37 and C38 longchain alkenones. These compounds are members of a class of lipids known collectively as polyunsaturated long-chain al...

  5. Salinity dependent hydrogen isotope fractionation in alkenones produced by coastal and open ocean haptophyte algae

    NASA Astrophysics Data System (ADS)

    M'boule, Daniela; Chivall, David; Sinke-Schoen, Danielle; Sinninghe Damsté, Jaap S.; Schouten, Stefan; van der Meer, Marcel T. J.

    2014-04-01

    The hydrogen isotope fractionation in alkenones produced by haptophyte algae is a promising new proxy for paleosalinity reconstructions. To constrain and further develop this proxy the coastal haptophyte Isochrysis galbana and the open ocean haptophyte alga Emiliania huxleyi were cultured at different salinities. The fractionation factor, αalkenones-water, ranged between 0.853 and 0.902 for I. galbana and 0.789 and 0.822 for E. huxleyi. The results show a strong linear correlation between the fractionation factor α and salinity for E. huxleyi, in agreement with earlier studies, but also for I. galbana. Both haptophytes show the same response to changes in salinity, represented by the slopes of the α-salinity relationship (˜0.002 per salinity unit). This suggests that the same process, in both coastal as well as open ocean haptophytes, is responsible for reducing fractionation with increasing salinity. However, there is a significant difference in absolute isotope fractionation between E. huxleyi and I. galbana, i.e. E. huxleyi produces alkenones which are 90‰ more depleted in D under the same culturing conditions than I. galbana. Our data suggest that the δD of alkenones can be used to reconstruct relative shifts in paleosalinity in coastal as well as open ocean environments with careful consideration of species composition and other complicating factors especially in coastal regions.

  6. Mean sea surface and gravity investigations using TOPEX/Poseidon altimeter data

    NASA Technical Reports Server (NTRS)

    Rapp, Richard H.

    1991-01-01

    From a broad point of view, we will be concerned with studying global ocean circulation patterns on the basis of ocean surface determinations with geoid undulation information. In addition, we will study local variations of the gravity field implied by the altimeter data. These general goals are reflected in the title of our investigation. To meet our general goal, we have defined a number of specific objectives: (1) sea surface topography representation; (2) mean sea surface determination; (3) development of local geoid models; (4) mean sea surface comparisons; (5) sea surface topographic files; and (6) gravity anomaly determination.

  7. Alkenone paleothermometry: Biological lessons from marine sediment records off western South America

    NASA Astrophysics Data System (ADS)

    Prahl, Fredrick G.; Mix, Alan C.; Sparrow, Margaret A.

    2006-01-01

    An empirical global core-top calibration that relates the alkenone unsaturation index U37K' to mean annual SST (maSST) is statistically the same as that defined for a subarctic Pacific strain of Emiliania huxleyi (CCMP1742) grown exponentially in batch culture under isothermal conditions. Although both equations have been applied widely for paleoSST reconstruction, uncertainty still stems from two key ecological factors: variability in the details of biosynthesis among genetically distinct alkenone-producing strains, and impacts of non-thermal physiological growth factors on U37K'. New batch culture experiments with CCMP1742 here reveal that U37K' diverge systematically from the core-top calibration in response to nutrient depletion and light deprivation, two physiological stresses experienced by phytoplankton populations in the real ocean. Other aspects of alkenone/alkenoate composition also respond to these stresses and may serve as signatures of such effects, providing an opportunity to detect, understand, and potentially correct for such impacts on the geologic record. A test case documents that sediments from the Southeast Pacific display the alkenone/alkenoate compositional signature characteristic of cells physiologically stressed by light deprivation. Such an observation could be explained if marine snow provided a major vector of sedimentation for these biomarkers. Late Pleistocene U37K' records in the Southeast Pacific yield plausible paleotemperature histories of ice-age cooling, but ice-age alkenone/alkenoate signatures fall outside the range of modern calibration samples of similar U37K'. They better match core-top samples deposited beneath waters characterized by much cooler maSST, suggesting key features of ice-age ecology for alkenone-producing haptophytes were different from today, and that the U37K' index taken alone may misgauge the total range of ice-age cooling at these locations. Analysis of the full spectrum of alkenone/alkenoate compositions

  8. A multiproxy reconstruction of Hebridean Shelf Sea spring sea surface temperatures from 1805-2010 (Invited)

    NASA Astrophysics Data System (ADS)

    Reynolds, D.; Butler, P.; Williams, S.; Scourse, J. D.; Richardson, C.; Wanamaker, A. D.; Austin, W.; Cage, A.; Sayer, M.

    2013-12-01

    We present a multiproxy reconstruction of Hebridean shelf sea (Tiree Passage; NW Scotland) spring sea surface temperatures (SSTs) for the period AD 1805-2010. The reconstruction is based on growth increment series from the first absolutely dated annually-resolved multi-centennial Glycymeris glycymeris bivalve mollusc sclerochronology and is coupled with previously published stable oxygen isotopes (δ18O) from benthic foraminifera sampled from a dated sediment core from nearby Loch Sunart. The independent series contain significant correlations with SSTs across complementary frequency domains. The low frequency component of the sedimentary archive was combined with the mid and high frequency components of the G. glycymeris chronology indices to create a single multiproxy series. Split calibration-verification statistics (reduction of error, RE, coefficient of efficiency, CE, and R2) indicate that the multiproxy record, calibrated to local instrumental sea surface temperatures, contains significant precision and skill at reconstructing spring SSTs (RE=0.59, CE=0.26, R2=0.54). These data demonstrate that bivalve sclerochronologies, when combined with low frequency proxies such as sediment archives, can facilitate statistically robust reconstructions of palaeoceanographic variability over the late Holocene for hydrographically-significant regions of the temperate marine system previously void of annually-resolved archives. The reconstructed SSTs contain a general warming trend of 0.60 ×0.14oC per century. Only four years in the reconstructed period (1999, 2000, 2002 and 2003) exceed temperatures greater than two standard deviations higher than the reconstructed mean SST (9.03oC), whilst just three years in the first half of the 19th century (1835, 1838 and 1840) fall more than 2σ below the reconstructed mean (6.80oC).

  9. The dependence of sea surface roughness on wind-waves

    NASA Astrophysics Data System (ADS)

    Lange, B.; Johnson, H. K.; Larsen, S. E.; Højstrup, J.

    2003-04-01

    The wave age dependency of the non-dimensional sea surface roughness (also called Charnock parameter) is investigated with data from the new field measurement program at Rødsand in the Danish Baltic Sea. An increasing Charnock parameter with inverse wave age is found, which can be described by a power law relation of the form proposed by Johnson et al. (1998) and others. Friction velocity is a common quantity in both Charnock parameter and wave age. Thus self-correlation effects are unavoidable in the relation between them. The significance of self-correlation is investigated by employing an artificial 'data' set with randomised wave parameters. It is found that self-correlation severely influences the relation. For the Rødsand data set the difference between real and randomised 'data' was found to be within the measurement uncertainty. By using a small sub-set of the data it was found that the importance of self-correlation increases for a narrower range of wave age values. This agrees with the conclusion of Johnson et al. (1998), that due to the scatter and self-correlation problems the coefficients of the power law relation can only be obtained from the analysis of an aggregated data set with a wide wave age range combining measurements from several sites. The dependency between wave age and sea roughness has been discussed extensively in the literature with different and sometimes conflicting results. A wide range of coefficients has been found for the power law relation between Charnock parameter and wave age for different data sets. It is shown that self-correlation contributes to such differences, since it depends on the range of wave age values present in the data sets. Also, data are often selected for rough flow conditions with the Reynolds roughness number. It is shown that for data sets with large scatter this can lead to misleading results of the relation of wave age and Charnock parameter. Two different methods to overcome this problem are presented

  10. Growth phase dependent hydrogen isotopic fractionation in alkenone-producing haptophytes

    NASA Astrophysics Data System (ADS)

    Wolhowe, M. D.; Prahl, F. G.; Probert, I.; Maldonado, M.

    2009-08-01

    Recent works have investigated use of the hydrogen isotopic composition of C37 alkenones (δDK37s, lipid biomarkers of certain haptophyte microalgae, as an independent paleosalinity proxy. We discuss herein the factors impeding the success of such an application and identify the potential alternative use of δDK37s measurements as a proxy for non-thermal, physiological stress impacts on the U37K' paleotemperature index. Batch-culture experiments with the haptophyte Emiliania huxleyi (CCMP 1742) were conducted to determine the magnitude and variability of the isotopic contrasts between individual C37 alkenones. Further experiments were conducted with Emiliania huxleyi (CCMP 1742) andGephyrocapsa oceanica (PZ3-1) to determine whether, and to what extent, δDK37s varies between the physiological extremes of nutrient-replete exponential growth and nutrient-depleted senescence. Emiliania huxleyi was observed to exhibit an isotopic contrast between di- and tri-unsaturated C37 alkenones (αK37:3-K37:2≈0.97) that is nearly identical to that reported recently by others for environmental samples. Furthermore, this contrast appears to be constant with growth stage. The consistency of the offset across different growth stages suggests that a single, well-defined value for αK37:3-K37:2 may exist and that its use in an isotope mass-balance will allow accurate determination of δD values for individual alkenones without having to rely on time- and labor-intensive chemical separations. The isotopic fractionation between growth medium and C37 alkenones was observed to increase dramatically upon the onset of nutrient-depletion-induced senescence, suggesting that δDK37s may serve as an objective tool for recognizing and potentially correcting, at least semi-quantitatively, for the effects of nutrient stress on U37K' temperature records.

  11. Sea surface temperature anomalies in the South China Sea during mature phase of ENSO

    NASA Astrophysics Data System (ADS)

    Qiu, Fuwen; Pan, Aijun; Zhang, Shanwu; Cha, Jing; Sun, Haowei

    2016-05-01

    Based on the 18-year (1993-2010) National Centers for Environmental Prediction optimum interpolation sea surface temperature (SST) and simple ocean data assimilation datasets, this study investigated the patterns of the SST anomalies (SSTAs) that occurred in the South China Sea (SCS) during the mature phase of the El Niño/Southern Oscillation. The most dominant characteristic was that of the outof-phase variation between southwestern and northeastern parts of the SCS, which was influenced primarily by the net surface heat flux and by horizontal thermal advection. The negative SSTA in the northeastern SCS was caused mainly by the loss of heat to the atmosphere and because of the cold-water advection from the western Pacific through the Luzon Strait during El Niño episodes. Conversely, it was found that the anomalous large-scale atmospheric circulation and weakened western boundary current during El Niño episodes led to the development of the positive SSTA in the southwestern SCS.

  12. Assessing the potential for dimethylsulfide enrichment at the sea surface and its influence on air-sea flux

    NASA Astrophysics Data System (ADS)

    Walker, Carolyn F.; Harvey, Mike J.; Smith, Murray J.; Bell, Thomas G.; Saltzman, Eric S.; Marriner, Andrew S.; McGregor, John A.; Law, Cliff S.

    2016-09-01

    The flux of dimethylsulfide (DMS) to the atmosphere is generally inferred using water sampled at or below 2 m depth, thereby excluding any concentration anomalies at the air-sea interface. Two independent techniques were used to assess the potential for near-surface DMS enrichment to influence DMS emissions and also identify the factors influencing enrichment. DMS measurements in productive frontal waters over the Chatham Rise, east of New Zealand, did not identify any significant gradients between 0.01 and 6 m in sub-surface seawater, whereas DMS enrichment in the sea-surface microlayer was variable, with a mean enrichment factor (EF; the concentration ratio between DMS in the sea-surface microlayer and in sub-surface water) of 1.7. Physical and biological factors influenced sea-surface microlayer DMS concentration, with high enrichment (EF > 1.3) only recorded in a dinoflagellate-dominated bloom, and associated with low to medium wind speeds and near-surface temperature gradients. On occasion, high DMS enrichment preceded periods when the air-sea DMS flux, measured by eddy covariance, exceeded the flux calculated using National Oceanic and Atmospheric Administration (NOAA) Coupled-Ocean Atmospheric Response Experiment (COARE) parameterized gas transfer velocities and measured sub-surface seawater DMS concentrations. The results of these two independent approaches suggest that air-sea emissions may be influenced by near-surface DMS production under certain conditions, and highlight the need for further study to constrain the magnitude and mechanisms of DMS production in the sea-surface microlayer.

  13. Global monthly sea surface nitrate fields estimated from remotely sensed sea surface temperature, chlorophyll, and modeled mixed layer depth

    NASA Astrophysics Data System (ADS)

    Arteaga, Lionel; Pahlow, Markus; Oschlies, Andreas

    2015-02-01

    Information about oceanic nitrate is crucial for making inferences about marine biological production and the efficiency of the biological carbon pump. While there are no optical properties that allow direct estimation of inorganic nitrogen, its correlation with other biogeochemical variables may permit its inference from satellite data. Here we report a new method for estimating monthly mean surface nitrate concentrations employing local multiple linear regressions on a global 1° by 1° resolution grid, using satellite-derived sea surface temperature, chlorophyll, and modeled mixed layer depth. Our method is able to reproduce the interannual variability of independent in situ nitrate observations at the Bermuda Atlantic Time Series, the Hawaii Ocean Time series, the California coast, and the southern New Zealand region. Our new method is shown to be more accurate than previous algorithms and thus can provide improved information on temporal and spatial nutrient variations beyond the climatological mean at regional and global scales.

  14. Investigation of rain effects on Aquarius Sea Surface Salinity measurements

    NASA Astrophysics Data System (ADS)

    Santos-Garcia, Andrea; Jacob, María. Marta; Jones, W. Linwood; Asher, William E.; Hejazin, Yazan; Ebrahimi, Hamideh; Rabolli, Monica

    2014-11-01

    The Aquarius/SAC-D mission has been providing Sea Surface Salinity (SSS), globally over the ocean, for almost 3 years. As a member of the AQ/SAC-D Cal/Val team, the Central Florida Remote Sensing Laboratory has analyzed these salinity retrievals in the presence of rain and has noted the strong correlation between the spatial patterns of reduced SSS and the spatial distribution of rainfall. It was determined that this is the result of a cause and effect relationship, as opposed to SSS measurement errors. Hence, it is important to understand these SSS changes due to seawater dilution by rain and the associated near-surface salinity stratification. This paper addresses the effects of rainfall on the Aquarius (AQ) SSS retrieval using a macro-scale Rain Impact Model (RIM) in the region of high convective rain over the Inter-tropical Convergence Zone. This model, based on the superposition of a one-dimension eddy diffusion (turbulent diffusion) model, relates sea surface salinity to depth, rain accumulation and time since rainfall. For aiding in the identification of instantaneous and prior rainfall accumulations, an AQ Rain Accumulation product was developed. This product, based on the NOAA CMORPH rain data set, provides the rainfall history for 24 h prior to the observation time, which is integrated over each AQ SSS measurement cell. In this paper results of the RIM validation are presented by comparing AQ measured and RIM simulated SSS for several months of 2012. Results show the high cross correlation for these comparisons and also with the corresponding SSS anomalies relative to HYCOM.

  15. The sea surface microlayer: Biology, chemistry and anthropogenic enrichment

    NASA Astrophysics Data System (ADS)

    Hardy, J. T.

    Recent studies increasingly point to the interface between the world's atmosphere and hydrosphere (the sea-surface microlayer) as an important biological habitat and a collection point for anthropogenic materials. Newly developed sampling techniques collect different qualitative and quantitative fractions of the upper sea surface from depths of less than one micron to several centimeters. The microlayer provides a habitat for a biota, including the larvae of many commercial fishery species, which are often highly enriched in density compared to subsurface water only a few cm below. Common enrichments for bacterioneuston, phytoneuston, and zooneuston are 10 2-10 4, 1-10 2, and 1-10, respectively. The trophic relationships or integrated functioning of these neustonic communities have not been examined. Surface tension forces provide a physically stable microlayer, but one which is subjected to greater environmental and climatic variation than the water column. A number of poorly understood physical processes control the movement and flux of materials within and through the microlayer. The microlayer is generally coated with a natural organic film of lipid and fatty acid material overlying a polysaccharide protein complex. The microlayer serves as both a source and a sink for materials in the atmosphere and the water column. Among these materials are large quantities of anthropogenic substances which frequently occur at concentrations 10 2-10 4 greater than these in the water column. These include plastics, tar lumps, polyaromatic hydrocarbons, chlorrinated hydrocarbons, and potentially toxic metals, such as, lead, copper, zinc, and nickel. How the unique processes occurring in the microlayer affect the fate of anthropogenic substances is not yet clear. Many important questions remain to be examined.

  16. The dependence of sea surface slope on atmospheric stability and swell conditions

    NASA Technical Reports Server (NTRS)

    Hwang, Paul A.; Shemdin, Omar H.

    1988-01-01

    A tower-mounted optical device is used to measure the two-orthogonal components of the sea surface slope. The results indicate that an unstable stratification at the air-sea interface tends to enhance the surface roughness. The presence of a long ocean swell system steers the primary direction of shortwave propagation away from wind direction, and may increase or reduce the mean square slope of the sea surface.

  17. Persistence of Rainfall Imprint on SMOS Sea Surface Salinity

    NASA Astrophysics Data System (ADS)

    Boutin, Jacqueline; Reverdin, Gilles; Martin, Nicolas

    2015-04-01

    The Soil Moisture and Ocean Salinity (SMOS) satellite mission monitors sea surface salinity (SSS) over the global ocean for more than 5 years. In previous studies, Boutin et al. (2014) have shown a clear freshening of SMOS SSS under rain cells of about -0.14pss/mm/hr at moderate wind speed (3-12m/s). This order of magnitude is compatible with in situ drifters observations taken at 45cm depth while SMOS SSS are at about 1cm depth and at a mean spatial resolution of 43km. Using Aquarius satellite SSS, Meissner and Wentz (2014) found a SSS decrease under rain cells of -0.12pss/mm/hr at 7 m/s wind speed, consistent with SMOS estimate considering the lower spatial resolution of Aquarius SSS (about 150km); Santos-Garcia et al. (2014) found an influence of the rain history preceding by a few hours the Aquarius measurement. In most cases, drifters observations also suggest that about half of the freshening observed locally disappears after one hour, likely because of mixing with surrounding waters. In this presentation, we will investigate the temporal and spatial evolution of SMOS SSS after a rain event. Rainfall information will be either derived from SSM/Is measurements (during periods when three SSM/Is satellites provide adequate sampling before and simultaneous to SMOS measurements) or from the NOAA CMORPH products. In order to separate instantaneous from historical effects, we distinguish two cases: 1) rainfall occurs at less than 30mn from SMOS observation but no rain occurred before; 2) rainfall occurred previous to SMOS observation (up to 3 hours before) but has stopped at least 30mn before SMOS acquisition. In addition to looking at the temporal evolution of SMOS SSS under the rain cell, since both vertical mixing and horizontal stirring may occur, we also investigate the size of the fresh SSS region relative to the size of the rain cell. Boutin, J., N. Martin, G. Reverdin, S. Morisset, X. Yin, L. Centurioni, and N. Reul (2014), Sea surface salinity under rain

  18. Forward scattering of pulses from a rough sea surface by Fourier synthesis of parabolic equation solutions.

    PubMed

    Miles, David A; Hewitt, Robin N; Donnelly, Marcus K; Clarke, Timothy

    2003-09-01

    A variable depth step implementation of the range-dependent acoustic model (RAM) is applied to the modeling of forward scattering from a rough sea surface. The sea surface is treated within RAM simply as an internal interface between a water layer and an air upper halfspace. A comparison with a numerically exact integral equation is undertaken for the scattering of single frequencies from Pierson-Moskowitz sea surfaces. The method is extended to model the variability of linear frequency modulated pulses from a series of frozen sea surfaces in a shallow water waveguide. The subsequent effect of rough boundary scattering on the replica correlation process is investigated. PMID:14514180

  19. A Robust Mechanical Sensing System for Unmanned Sea Surface Vehicles

    NASA Technical Reports Server (NTRS)

    Kulczycki, Eric A.; Magnone, Lee J.; Huntsberger, Terrance; Aghazarian, Hrand; Padgett, Curtis W.; Trotz, David C.; Garrett, Michael S.

    2009-01-01

    The need for autonomous navigation and intelligent control of unmanned sea surface vehicles requires a mechanically robust sensing architecture that is watertight, durable, and insensitive to vibration and shock loading. The sensing system developed here comprises four black and white cameras and a single color camera. The cameras are rigidly mounted to a camera bar that can be reconfigured to mount multiple vehicles, and act as both navigational cameras and application cameras. The cameras are housed in watertight casings to protect them and their electronics from moisture and wave splashes. Two of the black and white cameras are positioned to provide lateral vision. They are angled away from the front of the vehicle at horizontal angles to provide ideal fields of view for mapping and autonomous navigation. The other two black and white cameras are positioned at an angle into the color camera's field of view to support vehicle applications. These two cameras provide an overlap, as well as a backup to the front camera. The color camera is positioned directly in the middle of the bar, aimed straight ahead. This system is applicable to any sea-going vehicle, both on Earth and in space.

  20. Bistatic scattering from a contaminated sea surface observed in C, X, and Ku bands

    NASA Astrophysics Data System (ADS)

    Ghanmi, H.; Khenchaf, A.; Comblet, F.

    2014-10-01

    The aim of the work presented in this paper focuses on the study and analysis of variations of the bistatic electromagnetic signature of the sea surface contaminated by pollutants. Therefore, we will start the numerical analyses of the pollutant effect on the geometrical and physical characteristics of sea surface. Then, we will evaluate the electromagnetic (EM) scattering coefficients of the clean and polluted sea surface observed in bistatic configuration by using the numerical Forward-Backward Method (FBM). The obtained numerical results of the electromagnetic scattering coefficients are studied and given as a function of various parameters: sea state, wind velocity, type of pollutant (sea surface polluted by oil emulsion, and sea surface covered by oil layer), incidence and scattering angles, frequencies bands (C, X and Ku) and radar polarization.

  1. Bistatic electromagnetic scattering and detection of pollutant on a sea surface

    NASA Astrophysics Data System (ADS)

    Ghanmi, Helmi; Khenchaf, Ali; Comblet, Fabrice

    2015-01-01

    We present the study and analysis of the variations of the bistatic electromagnetic (EM) signature of the sea surface contaminated by pollutants. Therefore, we start with the numerical analyses of the pollutant effect on the geometrical and physical characteristics of sea surface. Then, we evaluate the EM scattering coefficients of the clean and polluted sea surfaces observed in bistatic configuration by using the numerical forward-backward method. The obtained numerical results of the EM scattering coefficients are studied and given as a function of various parameters: sea state, wind velocity, type of pollutant (sea surface polluted by oil emulsion and sea surface covered by oil layer), incidence and scattering angles, frequencies bands (C, X, and Ku), and radar polarization.

  2. Tropical cyclone rainfall area controlled by relative sea surface temperature

    PubMed Central

    Lin, Yanluan; Zhao, Ming; Zhang, Minghua

    2015-01-01

    Tropical cyclone rainfall rates have been projected to increase in a warmer climate. The area coverage of tropical cyclones influences their impact on human lives, yet little is known about how tropical cyclone rainfall area will change in the future. Here, using satellite data and global atmospheric model simulations, we show that tropical cyclone rainfall area is controlled primarily by its environmental sea surface temperature (SST) relative to the tropical mean SST (that is, the relative SST), while rainfall rate increases with increasing absolute SST. Our result is consistent with previous numerical simulations that indicated tight relationships between tropical cyclone size and mid-tropospheric relative humidity. Global statistics of tropical cyclone rainfall area are not expected to change markedly under a warmer climate provided that SST change is relatively uniform, implying that increases in total rainfall will be confined to similar size domains with higher rainfall rates. PMID:25761457

  3. Satellite-Derived Sea Surface Temperature: Workshop 3

    NASA Technical Reports Server (NTRS)

    1985-01-01

    This is the third of a series of three workshops, sponsored by the National Aeronautics and Space Administration, to investigate the state of the art in global sea surface temperature measurements from space. Three workshops were necessary to process and analyze sufficient data from which to draw conclusions on the accuracy and reliability of the satellite measurements. In this workshop, the final two (out of a total of four) months of satellite and in situ data chosen for study were processed and evaluated. Results from the AVHRR, HIRS, SMMR, and VAS sensors, in comparison with in situ data from ships, XBTs, and buoys, confirmed satellite rms accuracies in the 0.5 to 1.0 C range, but with variable biases. These accuracies may degrade under adverse conditions for specific sensors. A variety of color maps, plots, and statistical tables are provided for detailed study of the individual sensor SST measurements.

  4. Wintertime sea surface temperature fronts in the Taiwan Strait

    NASA Astrophysics Data System (ADS)

    Chang, Yi; Shimada, Teruhisa; Lee, Ming-An; Lu, Hsueh-Jung; Sakaida, Futoki; Kawamura, Hiroshi

    2006-12-01

    We present wintertime variations and distributions of sea surface temperature (SST) fronts in the Taiwan Strait by applying an entropy-based edge detection method to 10-year (1996-2005) satellite SST images with grid size of 0.01°. From climatological monthly mean maps of SST gradient magnitude in winter, we identify four significant SST fronts in the Taiwan Strait. The Mainland China Coastal Front is a long frontal band along the 50-m isobath near the Chinese coast. The sharp Peng-Chang Front appears along the Peng-Hu Channel and extends northward around the Chang-Yuen Ridge. The Taiwan Bank Front evolves in early winter. As the winter progresses, the front becomes broad and moves toward the Chinese coast, connecting to the Mainland China Coastal Front. The Kuroshio Front extends northeastward from the northeastern tip of Taiwan with a semicircle-shape curving along the 100-m isobath.

  5. Investigation of Sea Surface Temperature (SST) anomalies over Cyprus area

    NASA Astrophysics Data System (ADS)

    Georgiou, Andreas; Akçit, Nuhcan

    2016-08-01

    The temperature of the sea surface has been identified as an important parameter of the natural environment, governing processes that occur in the upper ocean. This paper focuses on the analysis of the Sea Surface Temperature (SST) anomalies at the greater area of Cyprus. For that, SST data derived from MODerate-resolution Imaging Spectroradiometer (MODIS) instrument on board both Aqua and Terra sun synchronous satellites were used. A four year period was chosen as a first approach to address and describe this phenomenon. Geographical Information Systems (GIS) has been used as an integrated platform of analysis and presentation in addition of the support of MATLAB®. The methodology consists of five steps: (i) Collection of MODIS SST imagery, (ii) Development of the digital geo-database; (iii) Model and run the methodology in GIS as a script; (iv) Calculation of SST anomalies; and (v) Visualization of the results. The SST anomaly values have presented a symmetric distribution over the study area with an increase trend through the years of analysis. The calculated monthly and annual average SST anomalies (ASST) make more obvious this trend, with negative and positive SST changes to be distributed over the study area. In terms of seasons, the same increase trend presented during spring, summer, autumn and winter with 2013 to be the year with maximum ASST observed values. Innovative aspects comprise of straightforward integration and modeling of available tools, providing a versatile platform of analysis and semi-automation of the operation. In addition, the fine resolution maps that extracted from the analysis with a wide spatial coverage, allows the detail representation of SST and ASST respectively in the region.

  6. Surface buoyant plumes from melting icebergs in the Labrador Sea

    NASA Astrophysics Data System (ADS)

    Yankovsky, Alexander E.; Yashayaev, Igor

    2014-09-01

    Canada's Department of Fisheries and Oceans (DFO) conducts annual surveys in the Labrador Sea along the repeat hydrography line AR7W. The occupation of the AR7W line in May 2013 was followed by the experiment aimed at resolving the imprint of melting drifting icebergs on the upper layer thermohaline characteristics in the Labrador Sea. We present high-resolution observations around two icebergs conducted with the towed undulating platform Moving Vessel Profiler (MVP). The first iceberg drifted in relatively warm water of Atlantic origin (~2.5-3.1 °C) off Greenland, while the second iceberg was on the Labrador shelf in cold water below 0 °C. Both icebergs had a lengthscale of O(100 m). In both cases surface buoyant plumes fed by melt water and attached to the iceberg were observed. The plumes were evident in the anomalous thermohaline characteristics of the seawater. Their density anomalies were sufficiently strong to produce visible frontal structures, which imply a development of the intrinsic dynamics associated with a plume. The first plume formed over a time interval of ~10 h, while the second plume formed over several days and extended for more than 1 km (tenfold the iceberg's size). Strong vertical displacements of the pycnocline were observed near the second iceberg. They are interpreted as the internal wave wake. This interpretation is based on the temporal scale of these oscillations (local buoyancy frequency), as well as on the spatial orientation of these waves with respect to the iceberg drift relative to the pycnocline. The observed internal waves partially overlapped with the plume and affected its structure. The saline seawater splashing by swell contributed to the surface melting of the icebergs. Scaling analysis of the second plume suggests that it could be in the “rotational” dynamic regime with recirculating anticyclonic flow.

  7. The two-timescale response of Antarctic sea-surface temperature and sea-ice cover to ozone depletion

    NASA Astrophysics Data System (ADS)

    Ferreira, D.; Marshall, J.; Hausmann, U.

    2015-12-01

    In recent modelling work, we showed that the response of Antarctic sea-surface temperature and sea-ice cover to abrupt ozone depletion has two phases: a fast inter-annual (~1-5y) adjustment in which the surface ocean cools and sea-ice cover increases, followed by a slower decadal trend leading to a warming of the surface ocean and a reduction of sea-ice cover. I will first summarize the dynamics behind the two-timescale response and how it can help reconcile diverging views on the relationship between ozone depletion and Antarctic sea ice changes. Using numerical experiments, I will then show that knowledge of the two-timescale response can be used to predict how the coupled climate responds to a time-varying ozone distribution, such as one of depletion and recovery. These ideas will then be used to evaluate how 1) ozone depletion might have contributed to recent observed decadal Antarctic sea-ice trends and 2) the ozone-driven signal can emerge from natural variability. Finally, implications for the ability of coupled climate models to reproduce observed sea-ice trends will be discussed.

  8. Seasonal sea surface temperature anomaly prediction for coastal ecosystems

    NASA Astrophysics Data System (ADS)

    Stock, Charles A.; Pegion, Kathy; Vecchi, Gabriel A.; Alexander, Michael A.; Tommasi, Desiree; Bond, Nicholas A.; Fratantoni, Paula S.; Gudgel, Richard G.; Kristiansen, Trond; O'Brien, Todd D.; Xue, Yan; Yang, Xiasong

    2015-09-01

    Sea surface temperature (SST) anomalies are often both leading indicators and important drivers of marine resource fluctuations. Assessment of the skill of SST anomaly forecasts within coastal ecosystems accounting for the majority of global fish yields, however, has been minimal. This reflects coarse global forecast system resolution and past emphasis on the predictability of ocean basin-scale SST variations. This paper assesses monthly to inter-annual SST anomaly predictions in coastal "Large Marine Ecosystems" (LMEs). We begin with an analysis of 7 well-observed LMEs adjacent to the United States and then examine how mechanisms responsible for prediction skill in these systems are reflected in predictions for LMEs globally. Historical SST anomaly estimates from the 1/4° daily Optimal Interpolation Sea Surface Temperature reanalysis (OISST.v2) were first found to be highly consistent with in-situ measurements for 6 of the 7 U.S. LMEs. Thirty years of retrospective forecasts from climate forecast systems developed at NOAA's Geophysical Fluid Dynamics Laboratory (CM2.5-FLOR) and the National Center for Environmental Prediction (CFSv2) were then assessed against OISST.v2. Forecast skill varied widely by LME, initialization month, and lead but there were many cases of high skill that also exceeded that of a persistence forecast, some at leads greater than 6 months. Mechanisms underlying skill above persistence included accurate simulation of (a) seasonal transitions between less predictable locally generated and more predictable basin-scale SST variability; (b) seasonal transitions between different basin-scale influences; (c) propagation of SST anomalies across seasons through sea ice; and (d) re-emergence of previous anomalies upon the breakdown of summer stratification. Globally, significant skill above persistence across many tropical systems arises via mechanisms (a) and (b). Combinations of all four mechanisms contribute to less prevalent but nonetheless

  9. Hydraulic exchange between a coral reef and surface sea water

    SciTech Connect

    Tribble, G.W.; Sansone, F.J.; Li, Yuan-Hui

    1992-10-01

    Hydraulic exchange between overlying sea water and the internal structure of a patch reef in Kaneohe Bay, Oahu, Hawaii, was studied with an array of wells, 1, 2, and 4 m deep. Two natural chemical tracers, radon, and salinity, were used to calculate the exchange rate between surface sea water and reef interstitial waters. Dissolved radon concentrations are substantially higher in interstitial waters than is surface water. The degree of radon enrichment is quantitatively related to the time elapsed since interstitial water had equilibrated with the atmosphere. Residence time estimates are 1-40 days, with deeper wells having slower exchange. The average residence time for 1-m-deep wells was 2.1 days. A rainstorm-induced dilution of the salinity of Kaneohe Bay provides the second tracer. Samples of surface and reef interstitial waters following this salinity perturbation are used to calculate an average residence time of 2.6 days at a depth of 1 m and 42 days at a depth of 2 m. Three types of physical forces thought to cause exchange between surface and interstitial water are considered by measurement of the forcing functions and reef permeability. Hydraulic conductivities are about 50 m/d, with lower values near the seaward side of the reef. Most exchange seems to be caused by high-frequency, wave-driven oscillatory pumping and by unidirectional hydraulic head gradients (of uncertain origin) that are stable for at least 3-4 days. Wave-driven mixing is probably more important shallower in the reef, whereas head-driven flow may dominate deeper in the reef. Tidal pumping does not seem to contribute to exchange. All methods indicate that exchange in the upper part of Checker Reef is primarily through vertical exchange. The best estimate for the residence time of water at a depth of 1 m is 2 days. Water at depths of 204 m probably has a residence time of weeks to months. 49 refs., 8 figs., 6 tabs.

  10. The mean sea surface height and geoid along the Geosat subtrack from Bermuda to Cape Cod

    NASA Astrophysics Data System (ADS)

    Kelly, Kathryn A.; Joyce, Terrence M.; Schubert, David M.; Caruso, Michael J.

    1991-07-01

    Measurements of near-surface velocity and concurrent sea level along an ascending Geosat subtrack were used to estimate the mean sea surface height and the Earth's gravitational geoid. Velocity measurements were made on three traverses of a Geosat subtrack within 10 days, using an acoustic Doppler current profiler (ADCP). A small bias in the ADCP velocity was removed by considering a mass balance for two pairs of triangles for which expendable bathythermograph measurements were also made. Because of the large curvature of the Gulf Stream, the gradient wind balance was used to estimate the cross-track component of geostrophic velocity from the ADCP vectors; this component was then integrated to obtain the sea surface height profile. The mean sea surface height was estimated as the difference between the instantaneous sea surface height from ADCP and the Geosat residual sea level, with mesoscale errors reduced by low-pass filtering. The error estimates were divided into a bias, tilt, and mesoscale residual; the bias was ignored because profiles were only determined within a constant of integration. The calculated mean sea surface height estimate agreed with an independent estimate of the mean sea surface height from Geosat, obtained by modeling the Gulf Stream as a Gaussian jet, within the expected errors in the estimates: the tilt error was 0.10 m, and the mesoscale error was 0.044 m. To minimize mesoscale errors in the estimate, the alongtrack geoid estimate was computed as the difference between the mean sea level from the Geosat Exact Repeat Mission and an estimate of the mean sea surface height, rather than as the difference between instantaneous profiles of sea level and sea surface height. In the critical region near the Gulf Stream the estimated error reduction using this method was about 0.07 m. Differences between the geoid estimate and a gravimetric geoid were not within the expected errors: the rms mesoscale difference was 0.24 m rms.

  11. A case study of sea breeze blocking regulated by sea surface temperature along the English south coast

    NASA Astrophysics Data System (ADS)

    Sweeney, J. K.; Chagnon, J. M.; Gray, S. L.

    2013-09-01

    The sensitivity of sea breeze structure to sea surface temperature (SST) and coastal orography is investigated in convection-permitting Met Office Unified Model simulations of a case study along the south coast of England. Changes in SST of 1 K are shown to significantly modify the structure of the sea breeze. On the day of the case study the sea breeze was partially blocked by coastal orography, particularly within Lyme Bay. The extent to which the flow is blocked depends strongly on the static stability of the marine boundary layer. In experiments with colder SST, the marine boundary layer is more stable, and the degree of blocking is more pronounced. The implications of prescribing fixed SST from climatology in numerical weather prediction model forecasts of the sea breeze are discussed.

  12. Biofilm-like properties of the sea surface and predicted effects on air-sea CO2 exchange

    NASA Astrophysics Data System (ADS)

    Wurl, Oliver; Stolle, Christian; Van Thuoc, Chu; The Thu, Pham; Mari, Xavier

    2016-05-01

    Because the sea surface controls various interactions between the ocean and the atmosphere, it has a profound function for marine biogeochemistry and climate regulation. The sea surface is the gateway for the exchange of climate-relevant gases, heat and particles. Thus, in order to determine how the ocean and the atmosphere interact and respond to environmental changes on a global scale, the characterization and understanding of the sea surface are essential. The uppermost part of the water column is defined as the sea-surface microlayer and experiences strong spatial and temporal dynamics, mainly due to meteorological forcing. Wave-damped areas at the sea surface are caused by the accumulation of surface-active organic material and are defined as slicks. Natural slicks are observed frequently but their biogeochemical properties are poorly understood. In the present study, we found up to 40 times more transparent exopolymer particles (TEP), the foundation of any biofilm, in slicks compared to the underlying bulk water at multiple stations in the North Pacific, South China Sea, and Baltic Sea. We found a significant lower enrichment of TEP (up to 6) in non-slick sea surfaces compared to its underlying bulk water. Moreover, slicks were characterized by a large microbial biomass, another shared feature with conventional biofilms on solid surfaces. Compared to non-slick samples (avg. pairwise similarity of 70%), the community composition of bacteria in slicks was increasingly (avg. pairwise similarity of 45%) different from bulk water communities, indicating that the TEP-matrix creates specific environments for its inhabitants. We, therefore, conclude that slicks can feature biofilm-like properties with the excessive accumulation of particles and microbes. We also assessed the potential distribution and frequency of slick-formation in coastal and oceanic regions, and their effect on air-sea CO2 exchange based on literature data. We estimate that slicks can reduce CO2

  13. Horizontal advection, diffusion and plankton spectra at the sea surface.

    NASA Astrophysics Data System (ADS)

    Bracco, A.; Clayton, S.; Pasquero, C.

    2009-04-01

    Plankton patchiness is ubiquitous in the oceans, and various physical and biological processes have been proposed as its generating mechanisms. However, a coherent statement on the problem is missing, due to both a small number of suitable observations and to an incomplete understanding of the properties of reactive tracers in turbulent media. Abraham (1998) suggested that horizontal advection may be the dominant process behind the observed distributions of phytoplankton and zooplankton, acting to mix tracers with longer reaction times (Rt) down to smaller scales. Conversely, Mahadevan and Campbell (2002) attributed the relative distributions of sea surface temperature and phytoplankton to small scale upwelling, where tracers with longer Rt are able to homogenize more than those with shorter reaction times. Neither of the above mechanisms can explain simultaneously the (relative) spectral slopes of temperature, phytoplankton and zooplankton. Here, with a simple advection model and a large suite of numerical experiments, we concentrate on some of the physical processes influencing the relative distributions of tracers at the ocean surface, and we investigate: 1) the impact of the spatial scale of tracer supply; 2) the role played by coherent eddies on the distribution of tracers with different Rt; 3) the role of diffusion (so far neglected). We show that diffusion determines the distribution of temperature, regardless of the nature of the forcing. We also find that coherent structures together with differential diffusion of tracers with different Rt impact the tracer distributions. This may help in understanding the highly variable nature of observed plankton spectra.

  14. Sea, ice and surface water circulation, Alaskan continental shelf

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    The author has identified the following significant results. ERTS-1 imagery has been extremely useful in understanding the tidal water movements in a large estuary such as Cook Inlet. As more imagery obtained during various tidal stages become available it appears that complex and fast changing micro-circulation patterns develop in various regions of Cook Inlet during each advancing and receding tide. More ERTS-1 synoptic imagery is needed to fully understand the effect of the approach of tidal front on the water movements in the various regions through the estuary. The conventional onboard ship data gathered during various cruises although revealed the overall circulation pattern in Cook Inlet but failed to show micro-subgyres which develop in various regions during each tide which are discernible on ther ERTS-1 imagery. Suspended load distribution in the Bering Sea during summer varies significantly. In areas of phytoplankton bloom and at the river mouths the suspended load is higher than the 1 mg/1 which is found over most areas. The influence of major rivers on temperature, salinity, and suspended load in surface water as well as at shallow depth is apparent. On the Bering shelf a strong pycnocline generally at depth 10-20 m is formed by surface fresh water flow which retains sediment in suspension over extended periods.

  15. Long-Range Correlations of Global Sea Surface Temperature

    PubMed Central

    Jiang, Lei; Zhao, Xia; Wang, Lu

    2016-01-01

    Scaling behaviors of the global monthly sea surface temperature (SST) derived from 1870–2009 average monthly data sets of Hadley Centre Sea Ice and SST (HadISST) are investigated employing detrended fluctuation analysis (DFA). The global SST fluctuations are found to be strong positively long-range correlated at all pertinent time-intervals. The value of scaling exponent is larger in the tropics than those in the intermediate latitudes of the northern and southern hemispheres. DFA leads to the scaling exponent α = 0.87 over the globe (60°S~60°N), northern hemisphere (0°N~60°N), and southern hemisphere (0°S~60°S), α = 0.84 over the intermediate latitude of southern hemisphere (30°S~60°S), α = 0.81 over the intermediate latitude of northern hemisphere (30°N~60°N) and α = 0.90 over the tropics 30°S~30°N [fluctuation F(s) ~ sα], which the fluctuations of monthly SST anomaly display long-term correlated behaviors. Furthermore, the larger the standard deviation is, the smaller long-range correlations (LRCs) of SST in the corresponding regions, especially in three distinct upwelling areas. After the standard deviation is taken into account, an index χ = α * σ is introduced to obtain the spatial distributions of χ. There exists an obvious change of global SST in central east and northern Pacific and the northwest Atlantic. This may be as a clue on predictability of climate and ocean variabilities. PMID:27100397

  16. Declining Atmospheric pCO2 During the Late Miocene and Early Pliocene: New Insights from Paired Alkenone and Coccolith Stable Isotope Barometry

    NASA Astrophysics Data System (ADS)

    Phelps, S. R.; Polissar, P. J.; deMenocal, P. B.; Swann, J. P.; Guo, M. Y.; Stoll, H. M.

    2015-12-01

    The relationship between atmospheric CO2 concentrations and climate is broadly understood for the Cenozoic era: warmer periods are associated with higher atmospheric carbon dioxide. This understanding is supported by atmospheric samples of the past 800,000 years from ice cores, which suggest CO2 levels play a key role in regulating global climate on glacial interglacial timescales as well. In this context, the late Miocene poses a challenge: sea-surface temperatures indicate substantial global warmth, though existing data suggest atmospheric CO2 concentrations were lower than pre-industrial values. Recent work using the stable carbon and oxygen isotopic composition of coccolith calcite has demonstrated these organisms began actively diverting inorganic carbon away from calcification and to the site of photosynthesis during the late Miocene. This process occurs in culture experiments in response to low aqueous CO2 concentrations, and suggests decreasing atmospheric pCO2 values during the late Miocene. Here we present new data from ODP Site 806 in the western equatorial Pacific Ocean that supports declining atmospheric CO2 across the late Miocene. Carbon isotope values of coccolith calcite from Site 806 demonstrate carbon limitation and re-allocation of inorganic carbon to photosynthesis starting between ~8 and 6 Ma. The timing of this limitation at Site 806 precedes shifts at other ODP sites, reflecting the higher mixed layer temperature and resultant lower CO2 solubility at Site 806. New measurements of carbon isotope values from alkenones at Site 806 show an increase in photosynthetic carbon fractionation (ɛp) accompanied the carbon limitation evident from coccolith calcite stable isotope data. While higher ɛp is typically interpreted as higher CO2 concentrations, at Site 806, our data suggest it reflects enhancement of chloroplast CO2 from active carbon transport by the coccolithophore algae in response to lower CO2 concentrations. Our new data from ODP Site

  17. Impact of Interdecadal Sea Level and Sea Surface Temperature Variability on Primary Productivity and Harmful Algal Blooms in Southern California

    NASA Astrophysics Data System (ADS)

    Perry, K. L.

    2014-12-01

    Harmful Algal Blooms (HABs) are increasing in frequency and intensity on global, regional and local scales. Although climate change has been suggested as one of the key factors, very few interdecadal studies comparing HABs to low frequency physical forcing have been performed. Interannual to interdecadal variability in sea level and sea surface temperature along the Southern California Coast have been shown to have high correlation with the El Nino-La Nina signal. This is important in the study of phytoplankton, because abnormally low sea level corresponds to increased sea surface nutrient concentrations in this region. The California current is stronger during these times, and the higher nutrient water found to the north is advected southward. We have determined that primary productivity is most highly correlated with interdecadal sea level variability derived from tide gage data at a lag of approximately 2 months. This is consistent with previous zooplankton studies. In preparation for a potential El Nino event, we have expanded our analysis to include parameters such as sea surface temperature, salinity and nutrient concentrations from spaceborne and in situ instruments. We have also expanded our research to allow for analysis of several of the most prevalent HAB species. This work is the first step in our effort to create a model to predict and locate Southern California HAB events in the future.

  18. Global monitoring of Sea Surface Salinity with Aquarius

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    Aquarius is a microwave remote sensing system designed to obtain global maps of the surface salinity field of the oceans from space. It will be flown on the Aquarius/SAC-D mission, a partnership between the USA (NASA) and Argentina (CONAE) with launch scheduled for late in 2008. The objective of Aquarius is to monitor the seasonal and interannual variation of the large scale features of the surface salinity field in the open ocean. This will provide data to address scientific questions associated with ocean circulation and its impact on climate. For example, salinity is needed to understand the large scale thermohaline circulation, driven by buoyancy, which moves large masses of water and heat around the globe. Of the two variables that determine buoyancy (salinity and temperature), temperature is already being monitored. Salinity is the missing variable needed to understand this circulation. Salinity also has an important role in energy exchange between the ocean and atmosphere, for example in the development of fresh water lenses (buoyant water that forms stable layers and insulates water below from the atmosphere) which alter the air-sea coupling. Aquarius is a combination radiometer and scatterometer (radar) operating at L-band (1.413 GHz for the radiometer and 1.26 GHz for the scatterometer). The primary instrument,for measuring salinity is the radiometer which is able to detect salinity because of the modulation salinity produces on the thermal emission from sea water. This change is detectable at the long wavelength end of the microwave spectrum. The scatterometer will provide a correction for surface roughness (waves) which is one of the greatest unknowns in the retrieval. The sensor will be in a sun-synchronous orbit at about 650 km with equatorial crossings of 6am/6pm. The antenna for these two instruments is a 3 meter offset fed reflector with three feeds arranged in pushbroom fashion looking away from the sun toward the shadow side of the orbit to

  19. Estimation of Sea Surface Temperature (SST) Using Marine Seismic Data

    NASA Astrophysics Data System (ADS)

    Sinha, Satish Kumar; Dewangan, Pawan; Sain, Kalachand

    2016-04-01

    Not much attention is given to direct wave arrivals in marine seismic data that are acquired for petroleum exploration and prospecting. These direct arrivals are usually muted out in routine seismic data processing. In the present study, we process these direct arrivals to accurately estimate soundspeed in near-surface seawater and invert for sea surface temperature. The established empirical equation describing the relationships among temperature, salinity, pressure and soundspeed is used for the inversion. We also discuss processing techniques, such as first-break picking and cross-correlation for the estimation of soundspeed, that are well known among petroleum-industry geophysicists. The accuracy of the methods is directly linked to the data quality and signal processing. The novelty in our approach is in the data conditioning, which consists essentially of spectral balancing based on a wavelet transform that compensates for spherical spreading and increases the signal-to-noise ( S/ N) ratio. The 2D seismic data used in this paper are from the offshore Krishna-Godavari Basin east of India. We observe a significantly higher soundspeed of 1545 m/s for near-surface water than the commonly used value of ~1500 m/s. The estimated temperature (from velocity) is about 30 °C. Interestingly, the estimated temperature matches well with the temperature recorded in the CTD profile acquired in the study area during the month of May, the month corresponding to the acquisition of seismic data. Furthermore, the estimated temperatures during different times of data acquisition correlate well with the expected diurnal variation in temperature.

  20. Aquarius: A Mission to Monitor Sea Surface Salinity from Space

    NASA Technical Reports Server (NTRS)

    LeVine, D. M.; Lagerloef, G. S. E.; Pellerano, F.; Yueh, S.; Colomb, R.

    2006-01-01

    Aquarius is a combination radiometer and scatterometer (radar) operating at L-band (1.413 GHz for the radiometer and 1.26 GHz for the scatterometer). The primary instrument for measuring salinity is the radiometer. The scatterometer will provide a correction for surface roughness (waves) which is one of the largest potential sources of error in the retrieval. Unique features of the sensor are the large reflector (2.5 meter offset fed reflector with three feeds), polarimetric operation, and the tight thermal control. The three feeds produce three beams arranged to image in pushbroom fashion looking to the side of the orbit away from the sun to avoid sunglint. Polarimetric operation is included to assist in correcting for Faraday rotation which can be important at L-band. The tight thermal control is necessary to meet stability requirements (less than 0.12K drift over 7 days) which have been imposed to assist in meeting the science requirements for the retrieval of surface salinity (0.2 psu). The sensor will be in a sun-synchronous orbit at about 650 km with equatorial crossings of 6ad6pm (ascending at 6 pm). The objective is to monitor the seasonal and interannual variation of the large scale features of the surface salinity field in the open ocean. To accomplish this, the measurement goals are a spatial resolution of 100 km and retrieval accuracy of 0.2 psu globally on a monthly basis. Aquarius is being developed by NASA and is a partnership between JPL and the Goddard Space Flight Center. The SAC-D mission is being developed by CONAE and will include the spacecraft and several additional instruments, including visible and infrared cameras and a microwave radiometer to monitor rain and wind velocity over the oceans, and sea ice.

  1. Sound scattering by bubble clouds near the sea surface

    PubMed

    Gaunaurd; Huang

    2000-01-01

    The classical exact formulation required to evaluate the form function (or the scattering cross-section, SCS) of a single, ideal, air bubble in a boundless liquid is briefly recalled. It is then immediately generalized to the case of a round cloud of many possibly interacting such bubbles of known volume concentration, contained within the same boundless medium. This is further generalized to the case when the bubble cloud is near a free surface. The presence of the nearby pressure release surface, assumed flat, substantially alters the cloud's scattering cross-section relative to its value in the absence of boundaries. We then use an earlier technique of ours [i.e., see I.E.E.E. J. Ocean. Eng. 20, 285-293 (1995)] based on the method of images that uses the addition theorem for the spherical wave functions, to relate all the scattered sound fields to a common origin and thus obtain the (modified) SCS of the cloud now near the boundary. This formulation accounts for all orders of multiple scattering and yields an infinite set of coupled algebraic equations for the coupling coefficients. This set is then solved for the coupling coefficients in terms of infinite sums of products of pairs of Wigner 3-j symbols, which are then used to construct and evaluate the form function. We display numerical results in four cases that correspond to geographical sites in which the bubble concentrations within the cloud have been measured along a couple of oblique upward directions, or have been assumed to have increasing (and in a few instances, purposely unrealistically high) values. In all cases considered here the bubble clouds are only a few meters beneath the sea surface and consist of ideal bubbles. The results are also compared to those found in the absence of a boundary in all the cases considered.

  2. Mapping photosynthetically available radiation at the sea surface using GOCI

    NASA Astrophysics Data System (ADS)

    Choi, Jongkuk; Kim, Jihye; Yang, Hyun; Moon, Jeong-Eon; Frouin, Robert

    2016-04-01

    Photosynthetically available radiation (PAR) controls the composition of marine ecosystem by affecting the growth of phytoplankton, thus estimating PAR at the ocean surface accurately is important to understand the marine ecological environment. Although many studies have been attempted to estimate PAR employing ocean colour satellite data since 2003, previous studies using data from the polar orbit systems had spatial and temporal limitations to estimate accurate daily PAR. Here, we estimate daily PAR from Geostationary Ocean Colour Imager (GOCI) which collects data eight times a day at an hour interval in daytime and compare it with in-situ measurement and MODIS-based daily PAR. The algorithm we developed in this study, employed GOCI visible bands (centred at (412, 443, 490, 555, 660, 680 nm) which belongs to the range of PAR by calculating albedo at the layer of clouds and the sea surface to estimate daily PAR. The resultant value was validated by comparing the in-situ measurements acquired from an ocean research station, Socheongcho between February and May 2015, which showed a similar pattern with somewhat GOCI-base PAR's overestimations. The comparison with the results from MODIS, a polar orbit system showed that a good agreement with each other was illustrated at clear sky conditions, while MODIS showed some over- or underestimations at cloudy conditions with irregular patterns. This study shows that GOCI can estimate effectively the daily PAR with its advantages of acquiring data more frequently than other polar orbit ocean colour satellites by reducing the uncertainties induced by insufficient images to map the daily PAR at ocean surface.

  3. Surface Buoyant Plumes from Melting Icebergs in the Labrador Sea

    NASA Astrophysics Data System (ADS)

    Yankovsky, Alexander; Yashayaev, Igor

    2014-05-01

    Canada's Department of Fisheries and Oceans (DFO) conducts annual surveys in the Labrador Sea along the repeat hydrography line AR7W. Since 2012, these shipboard surveys have been supplemented by underway CTD and optical measurements in the upper 200 m layer conducted with the towed undulating platform Moving Vessel Profiler (MVP). The MVP hydrographic data reveal rich variability of the upper layer salinity field on different spatial scales. The occupation of the AR7W line in May 2013 was followed by the experiment aimed at resolving the imprint of melting drifting icebergs on the upper layer thermohaline characteristics in the Labrador Sea. Here we present observations around two icebergs: the first iceberg drifted in relatively warm water of Atlantic origin (~2.5-3.1°C) off Greenland, while the second iceberg was on the Labrador shelf in cold water below 0°C. Both icebergs had a lengthscale of O(100 m). In both cases surface buoyant plumes fed by melt water and attached to the iceberg were observed. The plumes were evident in the anomalous thermohaline characteristics of the seawater. Their density anomalies were sufficiently strong to produce visible frontal structures, which imply a development of the intrinsic dynamics associated with a plume. The first plume formed over a time interval of ~10 hr, while the second plume formed over several days and extended for more than 1 km (tenfold the iceberg's size). Strong vertical displacements of the pycnocline were observed near the second iceberg. They are interpreted as the internal wave wake. This interpretation is based on the temporal scale of these oscillations (local buoyancy frequency), as well as on the spatial orientation of these waves with respect to the iceberg drift relative to the pycnocline. The observed internal waves partially overlapped with the plume and affected its structure. The saline seawater splashing by swell contributed to the surface melting of the icebergs. Scaling analysis of the

  4. Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass

    PubMed Central

    O'Neil, Gregory W.; Williams, John R.; Wilson-Peltier, Julia; Knothe, Gerhard; Reddy, Christopher M.

    2016-01-01

    The need to replace petroleum fuels with alternatives from renewable and more environmentally sustainable sources is of growing importance. Biomass-derived biofuels have gained considerable attention in this regard, however first generation biofuels from edible crops like corn ethanol or soybean biodiesel have generally fallen out of favor. There is thus great interest in the development of methods for the production of liquid fuels from domestic and superior non-edible sources. Here we describe a detailed procedure for the production of a purified biodiesel from the marine microalgae Isochrysis. Additionally, a unique suite of lipids known as polyunsaturated long-chain alkenones are isolated in parallel as potentially valuable coproducts to offset the cost of biodiesel production. Multi-kilogram quantities of Isochrysis are purchased from two commercial sources, one as a wet paste (80% water) that is first dried prior to processing, and the other a dry milled powder (95% dry). Lipids are extracted with hexanes in a Soxhlet apparatus to produce an algal oil ("hexane algal oil") containing both traditional fats (i.e., triglycerides, 46-60% w/w) and alkenones (16-25% w/w). Saponification of the triglycerides in the algal oil allows for separation of the resulting free fatty acids (FFAs) from alkenone-containing neutral lipids. FFAs are then converted to biodiesel (i.e., fatty acid methyl esters, FAMEs) by acid-catalyzed esterification while alkenones are isolated and purified from the neutral lipids by crystallization. We demonstrate that biodiesel from both commercial Isochrysis biomasses have similar but not identical FAME profiles, characterized by elevated polyunsaturated fatty acid contents (approximately 40% w/w). Yields of biodiesel were consistently higher when starting from the Isochrysis wet paste (12% w/w vs. 7% w/w), which can be traced to lower amounts of hexane algal oil obtained from the powdered Isochrysis product. PMID:27404113

  5. Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass.

    PubMed

    O'Neil, Gregory W; Williams, John R; Wilson-Peltier, Julia; Knothe, Gerhard; Reddy, Christopher M

    2016-01-01

    The need to replace petroleum fuels with alternatives from renewable and more environmentally sustainable sources is of growing importance. Biomass-derived biofuels have gained considerable attention in this regard, however first generation biofuels from edible crops like corn ethanol or soybean biodiesel have generally fallen out of favor. There is thus great interest in the development of methods for the production of liquid fuels from domestic and superior non-edible sources. Here we describe a detailed procedure for the production of a purified biodiesel from the marine microalgae Isochrysis. Additionally, a unique suite of lipids known as polyunsaturated long-chain alkenones are isolated in parallel as potentially valuable coproducts to offset the cost of biodiesel production. Multi-kilogram quantities of Isochrysis are purchased from two commercial sources, one as a wet paste (80% water) that is first dried prior to processing, and the other a dry milled powder (95% dry). Lipids are extracted with hexanes in a Soxhlet apparatus to produce an algal oil ("hexane algal oil") containing both traditional fats (i.e., triglycerides, 46-60% w/w) and alkenones (16-25% w/w). Saponification of the triglycerides in the algal oil allows for separation of the resulting free fatty acids (FFAs) from alkenone-containing neutral lipids. FFAs are then converted to biodiesel (i.e., fatty acid methyl esters, FAMEs) by acid-catalyzed esterification while alkenones are isolated and purified from the neutral lipids by crystallization. We demonstrate that biodiesel from both commercial Isochrysis biomasses have similar but not identical FAME profiles, characterized by elevated polyunsaturated fatty acid contents (approximately 40% w/w). Yields of biodiesel were consistently higher when starting from the Isochrysis wet paste (12% w/w vs. 7% w/w), which can be traced to lower amounts of hexane algal oil obtained from the powdered Isochrysis product. PMID:27404113

  6. Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass.

    PubMed

    O'Neil, Gregory W; Williams, John R; Wilson-Peltier, Julia; Knothe, Gerhard; Reddy, Christopher M

    2016-06-24

    The need to replace petroleum fuels with alternatives from renewable and more environmentally sustainable sources is of growing importance. Biomass-derived biofuels have gained considerable attention in this regard, however first generation biofuels from edible crops like corn ethanol or soybean biodiesel have generally fallen out of favor. There is thus great interest in the development of methods for the production of liquid fuels from domestic and superior non-edible sources. Here we describe a detailed procedure for the production of a purified biodiesel from the marine microalgae Isochrysis. Additionally, a unique suite of lipids known as polyunsaturated long-chain alkenones are isolated in parallel as potentially valuable coproducts to offset the cost of biodiesel production. Multi-kilogram quantities of Isochrysis are purchased from two commercial sources, one as a wet paste (80% water) that is first dried prior to processing, and the other a dry milled powder (95% dry). Lipids are extracted with hexanes in a Soxhlet apparatus to produce an algal oil ("hexane algal oil") containing both traditional fats (i.e., triglycerides, 46-60% w/w) and alkenones (16-25% w/w). Saponification of the triglycerides in the algal oil allows for separation of the resulting free fatty acids (FFAs) from alkenone-containing neutral lipids. FFAs are then converted to biodiesel (i.e., fatty acid methyl esters, FAMEs) by acid-catalyzed esterification while alkenones are isolated and purified from the neutral lipids by crystallization. We demonstrate that biodiesel from both commercial Isochrysis biomasses have similar but not identical FAME profiles, characterized by elevated polyunsaturated fatty acid contents (approximately 40% w/w). Yields of biodiesel were consistently higher when starting from the Isochrysis wet paste (12% w/w vs. 7% w/w), which can be traced to lower amounts of hexane algal oil obtained from the powdered Isochrysis product.

  7. Mean sea surface and geoid gradient comparisons with TOPEX altimeter data

    NASA Technical Reports Server (NTRS)

    Rapp, Richard H.; Yi, Yuchan; Wang, Yan Ming

    1994-01-01

    Cycles 4 to 54 of TOPEX data have been analyzed through comparisons with the mean sea surface given on the disturbed geophysical data record (GDR). Two inverted barometer correction procedures were considered for the data reduction. One used a constant atmospheric pressure for all data while the one adopted for use, for most computations, introduced a cycle average pressure. The maximum difference between the two estimates was 3.0 cm with a clear annual signal. With the modified correction the TOPEX sea surface was compared to The Ohio State University (OSU) mean sea surface, given on the GDR, to estimate three translations ( delta x = -2.3 cm; delta y = 25.0 cm; delta z = -0.3 cm) and a bias (43.3 cm) between the two surfaces. The only significant translation is delta y which indicates the reference frame of the TOPEX system differs from that used in the OSU mean sea surface system. The bias between the TOPEX mean sea surface and the OSU mean sea surface was used to estimate an equatorial radius of 6,378,136.55 m based on an 18-cm biased estimate of the TOPEX altimeter. Examination of the average difference, by cycle, between the TOPEX sea surface and the OSU mean sea surface suggested a bias change of 3.1 +/- 2.2 mm/yr with a positive sign indicating the average ocean surface is rising or the altimeter measured distance is decreasing. Models were implemented that solved directly for a bias, bias rate annual/semiannual, and tide correction terms. The computations indicated that a simultaneous solution for this bias, bias rate, and annual/semiannual terms gave the most accurate results. Nonsimultaneous solutions led to slightly different bias rate values. The root mean square difference between the TOPEX sea surface and OSU sea surface, after translation and bias correction, was +/- 17 cm for a typical cycle. Some locations were indentified where the difference could reach 2.3 cm and were repeated over several cycles indicating errors in the mean sea surface. Most

  8. Sea level and turbidity controls on mangrove soil surface elevation change

    USGS Publications Warehouse

    Lovelock, Catherine E.; Fernanda Adame, Maria; Bennion, Vicki; Hayes, Matthew; Reef, Ruth; Santini, Nadia; Cahoon, Donald R.

    2015-01-01

    Increases in sea level are a threat to seaward fringing mangrove forests if levels of inundation exceed the physiological tolerance of the trees; however, tidal wetlands can keep pace with sea level rise if soil surface elevations can increase at the same pace as sea level rise. Sediment accretion on the soil surface and belowground production of roots are proposed to increase with increasing sea level, enabling intertidal habitats to maintain their position relative to mean sea level, but there are few tests of these predictions in mangrove forests. Here we used variation in sea level and the availability of sediments caused by seasonal and inter-annual variation in the intensity of La Nina-El Nino to assess the effects of increasing sea level on surface elevation gains and contributing processes (accretion on the surface, subsidence and root growth) in mangrove forests. We found that soil surface elevation increased with mean sea level (which varied over 250 mm during the study) and with turbidity at sites where fine sediment in the water column is abundant. In contrast, where sediments were sandy, rates of surface elevation gain were high, but not significantly related to variation in turbidity, and were likely to be influenced by other factors that deliver sand to the mangrove forest. Root growth was not linked to soil surface elevation gains, although it was associated with reduced shallow subsidence, and therefore may contribute to the capacity of mangroves to keep pace with sea level rise. Our results indicate both surface (sedimentation) and subsurface (root growth) processes can influence mangrove capacity to keep pace with sea level rise within the same geographic location, and that current models of tidal marsh responses to sea level rise capture the major feature of the response of mangroves where fine, but not coarse, sediments are abundant.

  9. Sea level and turbidity controls on mangrove soil surface elevation change

    NASA Astrophysics Data System (ADS)

    Lovelock, Catherine E.; Adame, Maria Fernanda; Bennion, Vicki; Hayes, Matthew; Reef, Ruth; Santini, Nadia; Cahoon, Donald R.

    2015-02-01

    Increases in sea level are a threat to seaward fringing mangrove forests if levels of inundation exceed the physiological tolerance of the trees; however, tidal wetlands can keep pace with sea level rise if soil surface elevations can increase at the same pace as sea level rise. Sediment accretion on the soil surface and belowground production of roots are proposed to increase with increasing sea level, enabling intertidal habitats to maintain their position relative to mean sea level, but there are few tests of these predictions in mangrove forests. Here we used variation in sea level and the availability of sediments caused by seasonal and inter-annual variation in the intensity of La Nina-El Nino to assess the effects of increasing sea level on surface elevation gains and contributing processes (accretion on the surface, subsidence and root growth) in mangrove forests. We found that soil surface elevation increased with mean sea level (which varied over 250 mm during the study) and with turbidity at sites where fine sediment in the water column is abundant. In contrast, where sediments were sandy, rates of surface elevation gain were high, but not significantly related to variation in turbidity, and were likely to be influenced by other factors that deliver sand to the mangrove forest. Root growth was not linked to soil surface elevation gains, although it was associated with reduced shallow subsidence, and therefore may contribute to the capacity of mangroves to keep pace with sea level rise. Our results indicate both surface (sedimentation) and subsurface (root growth) processes can influence mangrove capacity to keep pace with sea level rise within the same geographic location, and that current models of tidal marsh responses to sea level rise capture the major feature of the response of mangroves where fine, but not coarse, sediments are abundant.

  10. 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.

  11. Extracting the Global Sea Surface Temperature Evolutions of Different Timescales

    NASA Astrophysics Data System (ADS)

    Feng, J.; Wu, Z.

    2012-12-01

    A new data analysis procedure, involving empirical orthogonal functions (EOF) analysis and ensemble empirical mode decomposition (EEMD), is employed to extract the evolutions of global Sea Surface Temperature (SST) of different timescales spanning the period from 1880 to 2009 (130 yr). Specifically, EOF analysis serves as a means of lossy data compression to eliminate the spatial-temporally incoherent, noise-like part of the data; and EEMD decomposes SST time series into different time scales, which facilitates research on SST-related weather and climate phenomena that have various timescales. Through validation, it is shown that the difference between the results and the original SST time series are mostly white noises, both spatially and temporally incoherent. We apply the results to study El Niño-Southern Oscillation (ENSO) events. Each ENSO event is examined and we find an oceanic region off Baja California coast ( ) that is instrumental to some ENSO events, especially those recently called ENSO Modoki, whose initial warming may be traced back to earlier warming signals from Baja California.

  12. Method for modelling sea surface clutter in complicated propagation environments

    NASA Astrophysics Data System (ADS)

    Dockery, G. D.

    1990-04-01

    An approach for predicting clutter levels in complicated propagation conditions using an advanced propagation model and one of several empirical clutter cross-section models is described. Incident power and grazing angle information is obtained using a parabolic equation/Fourier split-step technique to predict the distribution of energy in complicated, range-varying environments. Such environments also require the use of an algorithm that establishes a physically reasonable range-interpolation scheme for the measured refractivity profiles. The reflectivity of the sea surface is represented using a clutter cross-section model that was developed originally by the Georgia Institutue of Technology and subsequently modified to include the effects of arbitrary refractive conditions. Predicted clutter power levels generated by the new procedure are compared with clutter measured at 2.9 GHz during propagation experiments conducted at the NASA Wallops Flight Facility on Virginia's Eastern Shore. During these experiments, high-resolution refractivity data were collected in both range and altitude by an instrumented helicopter.

  13. The Effect of Ocean Currents on Sea Surface Temperature Anomalies

    NASA Technical Reports Server (NTRS)

    Stammer, Detlef; Leeuwenburgh, Olwijn

    2000-01-01

    We investigate regional and global-scale correlations between observed anomalies in sea surface temperature and height. A strong agreement between the two fields is found over a broad range of latitudes for different ocean basins. Both time-longitude plots and wavenumber-frequency spectra suggest an advective forcing of SST anomalies by a first-mode baroclinic wave field on spatial scales down to 400 km and time scales as short as 1 month. Even though the magnitude of the mean background temperature gradient is determining for the effectiveness of the forcing, there is no obvious seasonality that can be detected in the amplitudes of SST anomalies. Instead, individual wave signatures in the SST can in some cases be followed over periods of two years. The phase relationship between SST and SSH anomalies is dependent upon frequency and wavenumber and displays a clear decrease of the phase lag toward higher latitudes where the two fields come into phase at low frequencies. Estimates of the damping coefficient are larger than generally obtained for a purely atmospheric feedback. From a global frequency spectrum a damping time scale of 2-3 month was found. Regionally results are very variable and range from 1 month near strong currents to 10 month at low latitudes and in the sub-polar North Atlantic. Strong agreement is found between the first global EOF modes of 10 day averaged and spatially smoothed SST and SSH grids. The accompanying time series display low frequency oscillations in both fields.

  14. Ultra Stable Microwave Radiometers for Future Sea Surface Salinity Missions

    NASA Technical Reports Server (NTRS)

    Wilson, William J.; Tanner, Alan B.; Pellerano, Fernando A.; Horgan, Kevin A.

    2005-01-01

    The NASA Earth Science System Pathfinder (ESSP) mission Aquarius will measure global sea surface salinity with 100-km spatial resolution every 8 days with an average monthly salinity accuracy of 0.2 psu (parts per thousand). This requires an L-band low-noise radiometer with the long-term calibration stability of less than 0.1 K over 8 days. This three-year research program on ultra stable radiometers has addressed the radiometer requirements and configuration necessary to achieve this objective for Aquarius and future ocean salinity missions. The system configuration and component performance have been evaluated with radiometer testbeds at both JPL and GSFC. The research has addressed several areas including component characterization as a function of temperature, a procedure for the measurement and correction for radiometer system non-linearity, noise diode calibration versus temperature, low noise amplifier performance over voltage, and temperature control requirements to achieve the required stability. A breadboard radiometer, utilizing microstrip-based technologies, has been built to demonstrate this long-term stability. This report also presents the results of the radiometer test program, a detailed radiometer noise model, and details of the operational switching sequence optimization that can be used to achieve the low noise and stability requirements. Many of the results of this research have been incorporated into the Aquarius radiometer design and will allow this instrument to achieve its goals.

  15. Spatial Statistical Estimation for Massive Sea Surface Temperature Data

    NASA Astrophysics Data System (ADS)

    Marchetti, Y.; Vazquez, J.; Nguyen, H.; Braverman, A. J.

    2015-12-01

    We combine several large remotely sensed sea surface temperature (SST) datasets to create a single high-resolution SST dataset that has no missing data and provides an uncertainty associated with each value. This high resolution dataset will optimize estimates of SST in critical parts of the world's oceans, such as coastal upwelling regions. We use Spatial Statistical Data Fusion (SSDF), a statistical methodology for predicting global spatial fields by exploiting spatial correlations in the data. The main advantages of SSDF over spatial smoothing methodologies include the provision of probabilistic uncertainties, the ability to incorporate multiple datasets with varying footprints, measurement errors and biases, and estimation at any desired resolution. In order to accommodate massive input and output datasets, we introduce two modifications of the existing SSDF algorithm. First, we compute statistical model parameters based on coarse resolution aggregated data. Second, we use an adaptive spatial grid that allows us to perform estimation in a specified region of interest, but incorporate spatial dependence between locations in that region and all locations globally. Finally, we demonstrate with a case study involving estimations on the full globe at coarse resolution grid (30 km) and a high resolution (1 km) inset for the Gulf Stream region.

  16. Laser imaging of small surface vessels and people at sea

    NASA Astrophysics Data System (ADS)

    Steinvall, Ove; Elmqvist, Magnus; Karlsson, Kjell; Larsson, Håkan; Axelsson, Maria

    2010-04-01

    The development of new asymmetric threats to civilian and naval ships has been a relatively recent occurrence. The bombing of the USS Cole is one example and the pirate activities outside Somalia another. There is a need to recognize targets at long ranges and possibly also their intentions to prepare for counteractions. Eye safe laser imaging at 1.5 μm offers target recognition at long ranges during day and night. The 1.5 μm wavelength is suitable for observing small targets at the sea surface such as boats and swimmers due to the low reflectivity of water compared to potential targets. Turbulence and haze limits the sensor performance and their influence is estimated for some cases of operational interest. For comparison, passive EO images have been recorded with the same camera to investigate the difference between sun illuminated and laser illuminated images. Examples of laser images will be given for a variety of targets and external conditions.Image segmentation for future automated recognition development is described and examplified. Examples of relevant 1.5 μm laser reflectivities of small naval targets are also presented. Finally a discussion of system aspects is made.

  17. Investigating the use of paired Uk'37 and TEX86 measurements to reconstruct past sea surface and subsurface (thermocline) temperatures (Invited)

    NASA Astrophysics Data System (ADS)

    Castaneda, I. S.; Urann, B.; Phu, V.

    2013-12-01

    Two organic geochemical temperature proxies widely applied to marine sediments are the Uk'37 Index, based on long-chain alkenones produced by haptophyte algae, and TEX86, based on isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs), produced by Thaumarchaeota. At some locations, temperature reconstructions based on Uk'37 and TEX86 are in agreement within the calibration errors of each proxy, while at other sites absolute Uk'37 and TEX86 reconstructed temperatures differ but both proxies reveal similar overall trends (e.g. Caley et al., 2011). In contrast, at other locations Uk'37 and TEX86 temperature reconstructions from the same samples yield dramatically different overall trends. Differences observed between Uk'37 and TEX86 temperature reconstructions have been attributed to a variety of factors including seasonal production biases, differences in preservation and lateral transport, and differences related to the depth habitat of the source organisms. An increasing number of studies have provided evidence that TEX86 likely reflects a subsurface water temperature in certain areas of the world's oceans and have used paired Uk'37 and TEX86 measurements to simultaneously examine sea surface and subsurface (in some cases thermocline) temperature variability (e.g. Lopes dos Santos et al., 2010; Rommerskirchen et al., 2011; Li et al., 2013). In the tropical N Atlantic, a distinctive signature of Atlantic Meridional Overturning Circulation (AMOC) slowdown is anticorrelated variation between surface and subsurface water temperatures (e.g. Chang et al., 2008; Zhang et al., 2007) where sea surface temperature (SST) cooling is accompanied by shallow subsurface warming (e.g. Chang et al., 2008). Lopes dos Santos et al. (2010) examined a site in the tropical NE Atlantic where they showed that in the modern Uk'37 reflects SST while TEXH86 likely reflects a thermocline temperature. The authors noted several periods during the past 200 kyr when surface cooling and

  18. The relationship between sea surface temperature and chlorophyll concentration of phytoplanktons in the Black Sea using remote sensing techniques.

    PubMed

    Kavak, Mehmet Tahir; Karadogan, Sabri

    2012-04-01

    Present work investigated the relationship between Chlorophyll (Chl), of phytoplankton biomass, and sea surface temperature (SST) of the Black Sea, using Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Advanced Very High Resolution Radiometer (AVHRR) satellite imagery. Satellite derived data could provide information on the amount of sea life present (Brown algae, called kelp, proliferate, supporting new species of sea life, including otters, fish, and various invertebrates) in a given area throughout the world. SST from AVHRR from 1993 to 2008 showed seasonal, annual and interannual variability of temperature, monthly variability Chl from SeaWiFS from 1997 to 2009 has also been investigated. Chl showed two high peaks for the year 1999 and 2008. The correlation between SST and Chl for the same time has been found to be 60%. Correlation was significant at p<0.05. The information could also be useful in connection with studies of global changes in temperature and what effect they could have on the total abundance of marine life.

  19. Propagation and transformation of waters of the surface desalinated layer in the Kara Sea

    NASA Astrophysics Data System (ADS)

    Zatsepin, A. G.; Kremenetskiy, V. V.; Kubryakov, A. A.; Stanichny, S. V.; Soloviev, D. M.

    2015-07-01

    A new method for the calculating propagation of brackish waters from the Ob-Yenisei estuary in the Kara Sea is proposed. This method is based on satellite altimetry measurements and meteorological data. Surface currents in the upper layer are estimated as the sum of geostrophic and parameterized wind-driven transport. Geostrophic velocities are calculated using altimetry-derived sea-level anomalies and mean dynamic topography. The method has been used previously to calculate surface currents in the Black Sea [7, 12]. In this paper it has been successfully verified on the basis of comparisons with field observations of surface salinity and satellite images of sea-surface chlorophyll in the Kara Sea.

  20. The ICESat Arctic-Ocean Mean Sea Surface: Reference Field for Future Satellite and Airborne Altimetry over Sea Ice

    NASA Astrophysics Data System (ADS)

    Farrell, S. L.; McAdoo, D. C.; Zwally, H. J.; Yi, D.

    2010-12-01

    The era of ICESat operations, between 2003 and 2009, encompassed a period of significant change in the sea ice cover of the Arctic Ocean. Geoscience Laser Altimeter System (GLAS) data gathered during this period has been crucial for monitoring a decline in Arctic sea ice freeboard and thickness, particularly over perennial sea ice. An over-all loss of ice pack volume was recorded, including an observed 42 % loss of ice volume during the ICESat Fall (October/November) campaigns. Critical to the derivation of sea ice freeboard, and ice thickness, is precise mapping of the local reference sea level, the sea surface height (SSH). ICESat profiles over sea ice must be carefully assessed to discriminate leads from sea ice floes, so as to generate SSH profiles. Here we discuss methods for combining these local sea level measurements from the entire ICESat mission (using data from 16 ICESat campaigns) while maintaining the high along-track resolution of the GLAS footprints. We construct a high-resolution mean sea surface (MSS) model, which will be useful in itself as a reference field for retrieving sea ice freeboard from measurements gathered by CryoSat-2 and the Operation IceBridge aircraft campaigns. This Arctic MSS topography has additional oceanographic and geodetic applications. The MSS conforms closely to the marine geoid such that differences between these surfaces may be attributed to mean dynamic topography (MDT), from which mean ocean circulation may be derived. However, remaining errors in both the MSS field (e.g. unmodeled tidal effects) and the state-of-the-art geoids (particularly at short wavelengths), restrict the resolution at which MDT may be resolved. By combining this new ICESat MSS with geoids derived from satellite-only gravity data, such as data from the Gravity Recovery And Climate Experiment (GRACE) and the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellites, we show an improved capability for observing Arctic Ocean dynamic

  1. Growth phase dependent hydrogen isotopic fractionation in alkenone-producing haptophytes

    NASA Astrophysics Data System (ADS)

    Wolhowe, M. D.; Prahl, F. G.; Probert, I.; Maldonado, M.

    2009-04-01

    Several recent works have investigated use of the hydrogen isotopic composition of C37 alkenones (δDK37s), lipid biomarkers of certain haptophyte microalgae, as an independent paleosalinity proxy. We discuss herein the factors impeding the success of such an application and identify the potential alternative use of δDK37s measurements as a proxy for non-thermal, physiological stress impacts on the U37K' paleotemperature index. Batch-culture experiments with the haptophyte Emiliania huxleyi (CCMP 1742) were conducted to determine the magnitude and variability of the isotopic contrasts between individual C37 alkenones, an analytical impediment to the use of δDK37s in any paleoceanographic context. Further experiments were conducted with Emiliania huxleyi (CCMP 1742) and Gephyrocapsa oceanica (PZ3-1) to determine whether, and to what extent, δDK37s varies between the physiological extremes of nutrient-replete exponential growth and nutrient-depleted senescence, the basis for our proposed use of the measurement as an indicator of stress. Emiliania huxleyi exhibited an isotopic contrast between di- and tri-unsaturated C37 alkenones (αK37:3-K37:2≈0.97) that is nearly identical to that reported recently by others for environmental samples. Furthermore, this contrast appears to be constant with growth stage. The consistency of the offset across different growth stages suggests that a single, well-defined value for αK37:3-K37:2 exists and that its use in an isotope mass-balance will allow accurate determination of δD values for individual alkenones without having to rely on time- and labor-intensive chemical separations. The isotopic fractionation between growth medium and C37 alkenones was observed to increase dramatically upon the onset of nutrient-depletion-induced senescence, suggesting that δDK37s may serve as an objective tool for recognizing and potentially correcting, at least semi-quantitatively, for the effects of nutrient stress on U37K' temperature

  2. Holocene Sea Surface and Subsurface Water Mass Variability Reconstructed from Temperature and Sea-ice Proxies in Fram Strait

    NASA Astrophysics Data System (ADS)

    Werner, Kirstin; Spielhagen, Robert F.; Müller, Juliane; Husum, Katrine; Kandiano, Evgenia S.; Polyak, Leonid

    2016-04-01

    In two high-resolution sediment cores from the West Spitsbergen continental margin we investigated planktic foraminiferal, biomarker and dinocyst proxy data in order to reconstruct surface and subsurface water mass variability during the Holocene. The two study sites are today influenced by northward flowing warm and saline Atlantic Water. Both foraminiferal and dinocyst (de Vernal et al., 2013) temperature reconstructions indicate a less-stratified, ice-free, nutrient-rich summer surface ocean with strong Atlantic Water advection between 10.6 and 8.5 cal ka BP, likely related to maximum July insolation during the early Holocene. Sea surface to subsurface water temperatures of up to 6°C prevailed until ca 5 cal ka BP. A weakened contribution of Atlantic Water is found when subsurface temperatures strongly decreased with minimum values between ca 4 and 3 cal ka BP. High planktic foraminifer shell fragmentation and increased oxygen isotope values of the subpolar planktic foraminifer species Turborotalita quinqueloba as well as increasing concentrations of the sea ice biomarker IP25 further indicate cool conditions. Indices associated with IP25 as well as dinocyst data suggest a sustained cooling and consequently sea-ice increase during the late Holocene. However, planktic foraminiferal data indicate a slight return of stronger subsurface influx of Atlantic Water since ca 3 cal ka BP. The observed decoupling of cooling surface and warming subsurface waters during the later Holocene might be attributed to a strong pycnocline layer separating cold sea-ice fed surface waters from enhanced subsurface Atlantic Water advection. Reference: de Vernal, A., Hillaire-Marcel, C., Rochon, A., Fréchette, B., Henry, M., Solignac, S., Bonnet, S., 2013. Dinocyst-based reconstructions of sea ice cover concentration during the Holocene in the Arctic Ocean, the northern North Atlantic Ocean and its adjacent seas. Quaternary Science Reviews 79, 111-121.

  3. Arctic Sea Salt Aerosol from Blowing Snow and Sea Ice Surfaces - a Missing Natural Source in Winter

    NASA Astrophysics Data System (ADS)

    Frey, M. M.; Norris, S. J.; Brooks, I. M.; Nishimura, K.; Jones, A. E.

    2015-12-01

    Atmospheric particles in the polar regions consist mostly of sea salt aerosol (SSA). SSA plays an important role in regional climate change through influencing the surface energy balance either directly or indirectly via cloud formation. SSA irradiated by sunlight also releases very reactive halogen radicals, which control concentrations of ozone, a pollutant and greenhouse gas. However, models under-predict SSA concentrations in the Arctic during winter pointing to a missing source. It has been recently suggested that salty blowing snow above sea ice, which is evaporating, to be that source as it may produce more SSA than equivalent areas of open ocean. Participation in the 'Norwegian Young Sea Ice Cruise (N-ICE 2015)' on board the research vessel `Lance' allowed to test this hypothesis in the Arctic sea ice zone during winter. Measurements were carried out from the ship frozen into the pack ice North of 80º N during February to March 2015. Observations at ground level (0.1-2 m) and from the ship's crows nest (30 m) included number concentrations and size spectra of SSA (diameter range 0.3-10 μm) as well as snow particles (diameter range 50-500 μm). During and after blowing snow events significant SSA production was observed. In the aerosol and snow phase sulfate is fractionated with respect to sea water, which confirms sea ice surfaces and salty snow, and not the open ocean, to be the dominant source of airborne SSA. Aerosol shows depletion in bromide with respect to sea water, especially after sunrise, indicating photochemically driven release of bromine. We discuss the SSA source strength from blowing snow in light of environmental conditions (wind speed, atmospheric turbulence, temperature and snow salinity) and recommend improved model parameterisations to estimate regional aerosol production. N-ICE 2015 results are then compared to a similar study carried out previously in the Weddell Sea during the Antarctic winter.

  4. Electromagnetic backscattering from one-dimensional drifting fractal sea surface II: Electromagnetic backscattering model

    NASA Astrophysics Data System (ADS)

    Tao, Xie; William, Perrie; Shang-Zhuo, Zhao; He, Fang; Wen-Jin, Yu; Yi-Jun, He

    2016-07-01

    Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, the Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service Program.

  5. Electromagnetic backscattering from one-dimensional drifting fractal sea surface II: Electromagnetic backscattering model

    NASA Astrophysics Data System (ADS)

    Tao, Xie; William, Perrie; Shang-Zhuo, Zhao; He, Fang; Wen-Jin, Yu; Yi-Jun, He

    2016-07-01

    Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, the Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service Program.

  6. Terrestrial basking sea turtles are responding to spatio-temporal sea surface temperature patterns.

    PubMed

    Van Houtan, Kyle S; Halley, John M; Marks, Wendy

    2015-01-01

    Naturalists as early as Darwin observed terrestrial basking in green turtles (Chelonia mydas), but the distribution and environmental influences of this behaviour are poorly understood. Here, we examined 6 years of daily basking surveys in Hawaii and compared them with the phenology of local sea surface temperatures (SST). Data and models indicated basking peaks when SST is coolest, and we found this timeline consistent with bone stress markings. Next, we assessed the decadal SST profiles for the 11 global green turtle populations. Basking generally occurs when winter SST falls below 23°C. From 1990 to 2014, the SST for these populations warmed an average 0.04°C yr(-1) (range 0.01-0.09°C yr(-1)); roughly three times the observed global average over this period. Owing to projected future warming at basking sites, we estimated terrestrial basking in green turtles may cease globally by 2100. To predict and manage for future climate change, we encourage a more detailed understanding for how climate influences organismal biology.

  7. Terrestrial basking sea turtles are responding to spatio-temporal sea surface temperature patterns.

    PubMed

    Van Houtan, Kyle S; Halley, John M; Marks, Wendy

    2015-01-01

    Naturalists as early as Darwin observed terrestrial basking in green turtles (Chelonia mydas), but the distribution and environmental influences of this behaviour are poorly understood. Here, we examined 6 years of daily basking surveys in Hawaii and compared them with the phenology of local sea surface temperatures (SST). Data and models indicated basking peaks when SST is coolest, and we found this timeline consistent with bone stress markings. Next, we assessed the decadal SST profiles for the 11 global green turtle populations. Basking generally occurs when winter SST falls below 23°C. From 1990 to 2014, the SST for these populations warmed an average 0.04°C yr(-1) (range 0.01-0.09°C yr(-1)); roughly three times the observed global average over this period. Owing to projected future warming at basking sites, we estimated terrestrial basking in green turtles may cease globally by 2100. To predict and manage for future climate change, we encourage a more detailed understanding for how climate influences organismal biology. PMID:25589483

  8. Terrestrial basking sea turtles are responding to spatio-temporal sea surface temperature patterns

    PubMed Central

    Van Houtan, Kyle S.; Halley, John M.; Marks, Wendy

    2015-01-01

    Naturalists as early as Darwin observed terrestrial basking in green turtles (Chelonia mydas), but the distribution and environmental influences of this behaviour are poorly understood. Here, we examined 6 years of daily basking surveys in Hawaii and compared them with the phenology of local sea surface temperatures (SST). Data and models indicated basking peaks when SST is coolest, and we found this timeline consistent with bone stress markings. Next, we assessed the decadal SST profiles for the 11 global green turtle populations. Basking generally occurs when winter SST falls below 23°C. From 1990 to 2014, the SST for these populations warmed an average 0.04°C yr−1 (range 0.01–0.09°C yr−1); roughly three times the observed global average over this period. Owing to projected future warming at basking sites, we estimated terrestrial basking in green turtles may cease globally by 2100. To predict and manage for future climate change, we encourage a more detailed understanding for how climate influences organismal biology. PMID:25589483

  9. Polarimetric Doppler spectrum of backscattered echoes from nonlinear sea surface damped by natural slicks

    NASA Astrophysics Data System (ADS)

    Yang, Pengju; Guo, Lixin

    2016-11-01

    Based on the Lombardini et al. model that can predict the hydrodynamic damping of rough sea surfaces in the presence of monomolecular slicks and the "choppy wave" model (CWM) that can describe the nonlinear interactions between ocean waves, the modeling of time-varying nonlinear sea surfaces damped by natural or organic sea slicks is presented in this paper. The polarimetric scattering model of second-order small-slope approximation (SSA-II) with tapered wave incidence is utilized for evaluating co- and cross-polarized backscattered echoes from clean and contaminated CWM nonlinear sea surfaces. The influence of natural sea slicks on Doppler shift and spectral bandwidth of radar sea echoes is investigated in detail by comparing the polarimetric Doppler spectra of contaminated sea surfaces with those of clean sea surfaces. A narrowing of Doppler spectra in the presence of oil slicks is observed for both co- and cross-polarization, which is qualitatively consistent with wave-tank measurements. Simulation results also show that the Doppler shifts in slicks can increase or decrease, depending on incidence angles and polarizations.

  10. Black sea surface temperature anomaly on 5th August 1998 and the ozone layer thickness

    NASA Astrophysics Data System (ADS)

    Manev, A.; Palazov, K.; Raykov, St.; Ivanov, V.

    2003-04-01

    BLACK SEA SURFACE TEMPERATURE ANOMALY ON 5th AUGUST 1998 AND THE OZONE LAYER THICKNESS A. Manev , K. Palazov , St. Raykov, V. Ivanov Solar Terrestrial Influences Laboratory, Bulgarian Academy of Sciences amanev@abv.bg This paper focuses on the peculiarities of the Black Sea surface temperature anomaly on 05.08.1998. Researching the daily temperature changes in a number of control fields in the course of 8-10 years, we have found hidden correlations and anomalous deviations in the sea surface temperatures on a global scale. Research proves the statistical reliability of the temperature anomaly on the entire Black Sea surface registered on 04.-05.08.1998. In the course of six days around these dates the temperatures are up to 2°C higher than the maximum temperatures in this period in the other seven years. A more detailed analysis of the dynamics of the anomaly required the investigation of five Black Sea surface characteristic zones of 75x75 km. The analysis covers the period 20 days - 10 days before and 10 days after the anomaly. Investigations aimed at interpreting the reasons for the anomalous heating of the surface waters. We have tried to analyze the correlation between sea surface temperature and the global ozone above the Black Sea by using simultaneously data from the two satellite systems NOAA and TOMS. Methods of processing and comparing the data from the two satellite systems are described. The correlation coefficients values for the five characteristic zones are very high and close, which proves that the character of the correlation ozone - sea surface temperature is the same for the entire Black Sea surface. Despite the high correlation coefficient, we have proved that causality between the two phenomena at the time of the anomaly does not exit.

  11. Saltier sea surface water conditions recorded by multiple mid-Holocene corals in the northern South China Sea

    NASA Astrophysics Data System (ADS)

    Guo, Yangrui; Deng, Wenfeng; Chen, Xuefei; Wei, Gangjian; Yu, Kefu; Zhao, Jian-xin

    2016-08-01

    The typical features of the mid-Holocene can be used to better understand present-day climate conditions and the potential trends of future climate change. The surface conditions, including sea surface temperature (SST) and sea surface salinity (SSS), of the South China Sea (SCS) are largely controlled by the East Asian monsoon system. Surface water conditions reconstructed from coral proxies can be used to study the evolution of the East Asian monsoon during the mid-Holocene. However, there are some discrepancies among existing coral-based studies regarding whether the mid-Holocene sea surface water was much saltier than the present day surface waters. Based on paired Sr/Ca and δ18O of modern and three fossil corals, this paper reconstructs the patterns of seasonal variation in SSS during the mid-Holocene in the northern SCS. The Δδ18O records (a proxy for SSS) derived from the three fossil corals were all heavier than that from the modern coral, which suggests the presence of more saline surface waters during the mid-Holocene in the northern SCS. These results are consistent with previous studies based on records reconstructed from coral and foraminifera, as well as from numerical simulations. Reduced rainfall caused by the strengthened Asian Monsoon and/or the northward shift of the intertropical convergence zone during the mid-Holocene would explain the increased salinity of the surface waters of the northern SCS. The findings presented here clarify the discrepancies among previous studies and confirm the existence of saltier surface waters in the northern SCS during the mid-Holocene.

  12. Airborne Spectral Measurements of Surface-Atmosphere Anisotropy for Arctic Sea Ice and Tundra

    NASA Technical Reports Server (NTRS)

    Arnold, G. Thomas; Tsay, Si-Chee; King, Michael D.; Li, Jason Y.; Soulen, Peter F.

    1999-01-01

    Angular distributions of spectral reflectance for four common arctic surfaces: snow-covered sea ice, melt-season sea ice, snow-covered tundra, and tundra shortly after snowmelt were measured using an aircraft based, high angular resolution (1-degree) multispectral radiometer. Results indicate bidirectional reflectance is higher for snow-covered sea ice than melt-season sea ice at all wavelengths between 0.47 and 2.3 pm, with the difference increasing with wavelength. Bidirectional reflectance of snow-covered tundra is higher than for snow-free tundra for measurements less than 1.64 pm, with the difference decreasing with wavelength. Bidirectional reflectance patterns of all measured surfaces show maximum reflectance in the forward scattering direction of the principal plane, with identifiable specular reflection for the melt-season sea ice and snow-free tundra cases. The snow-free tundra had the most significant backscatter, and the melt-season sea ice the least. For sea ice, bidirectional reflectance changes due to snowmelt were more significant than differences among the different types of melt-season sea ice. Also the spectral-hemispherical (plane) albedo of each measured arctic surface was computed. Comparing measured nadir reflectance to albedo for sea ice and snow-covered tundra shows albedo underestimated 5-40%, with the largest bias at wavelengths beyond 1 pm. For snow-free tundra, nadir reflectance underestimates plane albedo by about 30-50%.

  13. Modes of variability of global sea surface temperature, free atmosphere temperature and oceanic surface energy flux

    SciTech Connect

    Hu, Wenjie; Newell, R.E.; Wu, Zhong-Xiang

    1994-11-01

    Monthly mean sea surface temperature (SST), free air temperature from satellite microwave sounding units (MSU) and oceanic surface energy fluxes are subjected to empirical orthogonal function (EOF) analysis for a common decade to investigate the physical relationships involved. The first seasonal modes of surface solar energy flux and SST show similar inter-hemispheric patterns with an annual cycle. Solar flux appears to control this pattern of SST. The first seasonal mode of MSU is similar with, additionally, land-sea differences; MSU is apparently partly controlled by absorption of solar near-infrared radiation and partly by sensible heat from from the land surface. The second and third seasonal eigenvector of SST and solar flux exhibit semi-annual oscillations associated with a pattern of cloudiness in the subtropics accompanying the translation of the Hadley cell rising motion between the hemispheres. The second seasonal mode of MSU is dominated by an El Nino Signal. The first nonseasonal EOFs of SST and solar flux exhibit El Nino characteristics with solar pattern being governed by west-to-east translation of a Walker cell type pattern. The first non-seasonal EOF of MSU shows a tropical strip pattern for the El Nino mode, which is well correlated with the latent heat fluxes in the tropical east Pacific but not in the tropical west Pacific. Two possible explanations are: an increase in subsidence throughout the tropical strip driven by extra evaporation in the tropical east Pacific and consequent additional latent heat liberation; a decrease of meridional heat flux out of the tropics. 56 refs., 12 figs., 5 tabs.

  14. Holocene and Last Glacial Maximum TEX86 and Globigerinoides ruber Mg/Ca Sea Surface Temperatures from the Eastern Equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Schmidt, M. W.; Hertzberg, J. E.; Bianchi, T. S.; Smith, R. W.; Shields, M. R.

    2012-12-01

    Although the eastern equatorial Pacific (EEP) exerts a major influence on tropical climate dynamics, there is considerable disagreement among various proxy reconstructions on the evolution of sea surface temperatures (SST) in this region since the Last Glacial Maximum (LGM). For example, foraminiferal Mg/Ca and alkenone UK'37 based SST reconstructions disagree on both the timing and magnitude of deglacial SST change in the EEP (Kienast et al., 2006; Lea et al., 2006), and it remains unclear how the SST gradient between the cold tongue and the warm pool to the north differed during the LGM (Koutavas and Lynch-Stieglitz, 2003). In order to better quantify regional SST change in the EEP, we will present companion reconstructions of Holocene SST change using both the molecular organic geochemical TEX86 index and Mg/Ca ratios in Globigerinoides ruber (white) from newly-acquired multicores on the Coco Ridge (MV1014-01-07MC; 6o14.0' N, 86o2.6' W; 1.2 - 3.5 kyr BP; 2.0 km depth) and Carnegie Ridge (MV1014-02-09MC; 0o41.6' S, 85o20.0' W; 2.3 - 6.9 kyr BP; 2.45 km depth). Reconstructed core-top values based on both proxies are in excellent agreement with modern average SSTs at each site. Furthermore, reconstructed Holocene TEX86 and Mg/Ca-SSTs are nearly identical within analytical error. To determine the relationship between TEX86 and Mg/Ca-SSTs in the past, we will also use both proxies to reconstruct LGM SSTs using radiocarbon-dated piston cores from the Cocos Ridge (MV1014-01-08JC; 6o14.0' N, 86o2.6' W; 2.0 km depth) and Carnegie Ridge (MV1014-02-17JC; 0o10.8' S, 85o52.0' W; 2.87 km depth). Kienast et al. (2006) Nature 443, 846-849. Koutavas and Lynch-Stieglitz (2003) Paleoceanography 18(4), 1089. Lea et al. (2006) Quat. Sci. Rev. 25, 1152-1167.

  15. Evaluating drivers of Pleistocene eastern tropical Pacific sea surface temperature

    NASA Astrophysics Data System (ADS)

    Dyez, K. A.; Ravelo, A. C.; Mix, A. C.

    2016-08-01

    Sea surface temperature (SST) of the eastern equatorial Pacific is a key component of tropical oceanic and atmospheric circulation with global teleconnections. Forcing factors such as local and high-latitude insolation changes, ice sheet size and albedo feedbacks, and greenhouse gas radiation have been proposed as controls of long-term eastern tropical Pacific SST, though the precise role each mechanism plays is not fully known on glacial-interglacial or longer timescales. Here proposed mechanisms are evaluated by comparing orbital-scale records of eastern Pacific SST with forcing variability over the past 1.5 Ma. The primary SST records are a compilation of new and existing data from Ocean Drilling Program Site 1239 at the northeastern margin of the modern eastern Pacific cold tongue and Site 846 SST within the cold tongue. Using time series analysis, we test previously proposed mechanisms for control of long-term tropical SST change and SST gradients in the eastern Pacific. We find that within statistical uncertainties, in the precession band eastern Pacific SST is consistent with direct forcing by equatorial radiation changes in the tropical cold season (summer-fall) rather than inversely correlated as previously suggested. In the obliquity band high-latitude solar forcing leads or is in phase with eastern equatorial Pacific SST, while in the eccentricity band atmospheric greenhouse gas concentrations are closely associated with cold tongue SST. Pleistocene eastern Pacific SST gradients indicate that the gradient on the northern margin of the cold tongue strengthened through the mid-Pleistocene transition, a result compatible with the cold tongue becoming more focused at ~900-650 ka.

  16. Methane excess in Arctic surface water- triggered by sea ice formation and melting

    NASA Astrophysics Data System (ADS)

    Damm, E.; Rudels, B.; Schauer, U.; Mau, S.; Dieckmann, G.

    2015-11-01

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas.

  17. Methane excess in Arctic surface water-triggered by sea ice formation and melting.

    PubMed

    Damm, E; Rudels, B; Schauer, U; Mau, S; Dieckmann, G

    2015-01-01

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas. PMID:26553610

  18. Methane excess in Arctic surface water-triggered by sea ice formation and melting.

    PubMed

    Damm, E; Rudels, B; Schauer, U; Mau, S; Dieckmann, G

    2015-11-10

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas.

  19. Methane excess in Arctic surface water- triggered by sea ice formation and melting

    PubMed Central

    Damm, E.; Rudels, B.; Schauer, U.; Mau, S.; Dieckmann, G.

    2015-01-01

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas. PMID:26553610

  20. Assimilation of Sea Surface Temperature in a doubly, two-way nested primitive equation model of the Ligurian Sea

    NASA Astrophysics Data System (ADS)

    Barth, A.; Alvera-Azcarate, A.; Rixen, M.; Beckers, J.-M.; Testut, C.-E.; Brankart, J.-M.; Brasseur, P.

    2003-04-01

    The GHER 3D primitive equation model is implemented with three different resolutions: a low resolution model (1/4^o) covering the whole Mediterranean Sea, an intermediate resolution model (1/20^o) of the Liguro-Provençal basin and a high resolution model (1/60^o) simulating the fine mesoscale structures in the Ligurian Sea. Boundary conditions and the averaged fields (feedback) are exchanged between two successive nesting levels. The model of the Ligurian Sea is also coupled with the assimilation package SESAM. It allows to assimilate satellite data and in situ observations using the local adaptative SEEK (Singular Evolutive Extended Kalman) filter. Instead of evolving the error space by the numerically expensive Lyapunov equation, a simplified algebraic equation depending on the misfit between observation and model forecast is used. Starting from the 1st January 1998 the low and intermediate resolution models are spun up for 18 months. The initial conditions for the Ligurian Sea are interpolated from the intermediate resolution model. The three models are then integrated until August 1999. During this period AVHRR Sea Surface Temperature of the Ligurian Sea is assimilated. The results are validated by using CTD and XBT profiles of the SIRENA cruise from the SACLANT Center. The overall objective of this study is pre-operational. It should help to identify limitations and weaknesses of forecasting methods and to suggest improvements of existing operational models.

  1. A case study of sea breeze blocking regulated by sea surface temperature along the English south coast

    NASA Astrophysics Data System (ADS)

    Sweeney, J. K.; Chagnon, J. M.; Gray, S. L.

    2014-05-01

    The sensitivity of sea breeze structure to sea surface temperature (SST) and coastal orography is investigated in convection-permitting Met Office Unified Model simulations of a case study along the south coast of England. Changes in SST of 1 K are shown to significantly modify the structure of the sea breeze immediately offshore. On the day of the case study, the sea breeze was partially blocked by coastal orography, particularly within Lyme Bay. The extent to which the flow is blocked depends strongly on the static stability of the marine boundary layer. In experiments with colder SST, the marine boundary layer is more stable, and the degree of blocking is more pronounced. Although a colder SST would also imply a larger land-sea temperature contrast and hence a stronger onshore wind - an effect which alone would discourage blocking - the increased static stability exerts a dominant control over whether blocking takes place. The implications of prescribing fixed SST from climatology in numerical weather prediction model forecasts of the sea breeze are discussed.

  2. SEASAT altimetry for surface height of inland seas

    NASA Technical Reports Server (NTRS)

    Welker, J. E.

    1984-01-01

    The capability of spaceborne altimetry to record the level, or monitor changes in the level, of inland seas was assessed. SEASAT altimetry data from Lake Baikal in Siberia; the Caspian, Black, and Aral Seas in the southern Soviet Union; the Great Salt Lake in the United States; lakes and reservoirs in northwestern and central China; and snow cover in northwestern India and on the Tibetan Plateau were examined.

  3. A Sea-Surface Radiation Data Set for Climate Applications in the Tropical Western Pacific and South China Sea

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah; Chan, Pui-King; Yan, Michael M.-H.

    2000-01-01

    The sea-surface shortwave and longwave radiative fluxes have been retrieved from the radiances measured by Japan's Geostationary Meteorological Satellite 5. The surface radiation data set covers the domain 40S-40N and 90E-170W. The temporal resolution is 1 day, and the spatial resolution is 0.5 deg x 0.5 deg latitude-longitude. The retrieved surface radiation have been validated with the radiometric measurements at the Atmospheric Radiation Measuring (ARM) site on Manus island in the equatorial western Pacific for a period of 15 months. It has also been validated with the measurements at the radiation site on Dungsha island in the South China Sea during the South China Sea Monsoon Experiment (SCSMEX) Intensive Observing Period (May and June 1998). The data set is used to study the effect of El Nino and East Asian Summer monsoon on the heating of the ocean in the tropical western Pacific and the South China Sea. Interannual variations of clouds associated with El Nino and the East Asian Summer monsoon have a large impact on the radiative heating of the ocean. It has been found that the magnitude of the interannual variation of the seasonal mean surface radiative heating exceeds 40 W/sq m over large areas. Together with the Clouds and the Earth's Radiant Energy System (CERES) shortwave fluxes at top of the atmosphere and the radiative transfer calculations of clear-sky fluxes, this surface radiation data set is also used to study the impact of clouds on the solar heating of the atmosphere. It is found that clouds enhance the atmospheric solar heating by approx. 20 W/sq m in the tropical western Pacific and the South China Sea. This result is important for evaluating the accuracy of solar flux calculations in clear and cloudy atmospheres.

  4. The effect of monomolecular surface films on the microwave brightness temperature of the sea surface

    NASA Technical Reports Server (NTRS)

    Alpers, W.; Blume, H.-J. C.; Garrett, W. D.; Huehnerfuss, H.

    1982-01-01

    It is pointed out that monomolecular surface films of biological origin are often encountered on the ocean surface, especially in coastal regions. The thicknesses of the monomolecular films are of the order of 3 x 10 to the -9th m. Huehnerfuss et al. (1978, 1981) have shown that monomolecular surface films damp surface waves quite strongly in the centimeter to decimeter wavelength regime. Other effects caused by films are related to the reduction of the gas exchange at the air-sea interface and the decrease of the wind stress. The present investigation is concerned with experiments which reveal an unexpectedly large response of the microwave brightness temperature to a monomolecular oleyl alcohol slick at 1.43 GHz. Brightness temperature is a function of the complex dielectric constant of thy upper layer of the ocean. During six overflights over an ocean area covered with an artificial monomolecular alcohol film, a large decrease of the brightness temperature at the L-band was measured, while at the S-band almost no decrease was observed.

  5. Surface microtopographies of tropical sea stars: lack of an efficient physical defence mechanism against fouling.

    PubMed

    Guenther, Jana; De Nys, Rocky

    2007-01-01

    The role of surface topography as a defence against fouling in tropical sea stars was investigated. The sea stars Linckia laevigata, Fromia indica, Cryptasterina pentagona and Archaster typicus are not fouled and have paxillae (modified ossicles with a median vertical pillar) on their aboral surfaces, which varied in diameter, height and distance depending on species and position on the aboral surface, providing unique and complex surface microtopographies for each species. The surfaces of the sea stars L. laevigata, F. indica and A. typicus were moderately wettable, with their mean seawater contact angles, calculated from captive bubble measurements, being 60.1 degrees, 70.3 degrees and 57.3 degrees, respectively. The seawater contact angle of C. pentagona could not be measured. To evaluate the effectiveness of the surface microtopographies in deterring the settlement of fouling organisms, field experiments with resin replicas of the four sea star species were conducted at three sites around Townsville, Australia, for 8 weeks during the dry and wet seasons. The fouling community and total fouling cover did not differ significantly between replicas of L. laevigata, F. indica, C. pentagona, A. typicus and control surfaces at any site during the dry season. Significant differences between fouling communities on the replicas of the sea stars and control surfaces were detected at two sites during the wet season. However, these differences were transitory, and the total fouling cover did not differ significantly between replicas of sea stars and control surfaces at two of the three sites. In contrast to recent literature on the effects of biofouling control by natural surfaces in the marine environment, the surface microtopographies of tropical sea stars alone were not effective in deterring the settlement and growth of fouling organisms.

  6. Regional studies using sea surface temperature fields derived from satellite infrared measurements

    NASA Technical Reports Server (NTRS)

    Strong, A. E.

    1972-01-01

    Three examples of sea surface temperature distributions over the western Atlantic are presented. These were detected by means of data from the scanning radiometer on the Improved Tiros Operational Satellite 1 (ITOS 1) under relatively clear sky conditions.

  7. Moderate-resolution sea surface temperature data for the Arctic Ocean Ecoregions

    EPA Science Inventory

    Sea surface temperature (SST) is an important environmental characteristic in determining the suitability and sustainability of habitats for marine organisms. Of particular interest is the fate of the Arctic Ocean, which provides critical habitat to commercially important fish (M...

  8. Moderate-Resolution Sea Surface Temperature Data for the Nearshore North Pacific

    EPA Science Inventory

    Coastal sea surface temperature (SST) is an important environmental characteristic defining habitat suitability for nearshore marine and estuarine organisms. The purpose of this publication is to provide access to an easy-to-use coastal SST dataset for ecologists, biogeographers...

  9. Physically-based Ice Thickness and Surface Roughness Retrievals over Rough Deformed Sea Ice

    NASA Astrophysics Data System (ADS)

    Li, Li; Gaiser, Peter; Allard, Richard; Posey, Pamela; Hebert, David; Richter-Menge, Jacqueline; Polashenski, Christopher; Claffey, Keran

    2016-04-01

    The observations of sea ice thickness and ice surface roughness are critical for our understanding of the state of the changing Arctic. Currently, the Radar and/or LiDAR data of sea ice freeboard are used to infer sea ice thickness via isostasy. The underlying assumption is that the LiDAR signal returns at the air/snow interface and radar signal at the snow/ice interface. The elevations of these interfaces are determined based on LiDAR/Radar return waveforms. However, the commonly used threshold-based surface detection techniques are empirical in nature and work well only over level/smooth sea ice. Rough sea ice surfaces can modify the return waveforms, resulting in significant Electromagnetic (EM) bias in the estimated surface elevations, and thus large errors in the ice thickness retrievals. To understand and quantify such sea ice surface roughness effects, a combined EM rough surface and volume scattering model was developed to simulate radar returns from the rough sea ice 'layer cake' structure. A waveform matching technique was also developed to fit observed waveforms to a physically-based waveform model and subsequently correct the roughness induced EM bias in the estimated freeboard. This new EM Bias Corrected (EMBC) algorithm was able to better retrieve surface elevations and estimate the surface roughness parameter simultaneously. Both the ice thickness and surface roughness retrievals are validated using in-situ data. For the surface roughness retrievals, we applied this EMBC algorithm to co-incident LiDAR/Radar measurements collected during a Cryosat-2 under-flight by the NASA IceBridge missions. Results show that not only does the waveform model fit very well to the measured radar waveform, but also the roughness parameters derived independently from the LiDAR and radar data agree very well for both level and deformed sea ice. For sea ice thickness retrievals, validation based on in-situ data from the coordinated CRREL/NRL field campaign demonstrates

  10. Characterization of Sea Lettuce Surface Functional Groups by Potentiometric Titrations

    NASA Astrophysics Data System (ADS)

    Ebling, A. M.; Schijf, J.

    2008-12-01

    In pursuit of our ultimate goal to better understand the prodigious capacity of the marine macroalga Ulva lactuca (sea lettuce) for adsorbing a broad range of dissolved trace metals from seawater, we performed an initial characterization of its surface functional groups. Specifically, the number of distinct functional groups as well as their individual bulk concentrations and acid dissociation constants (pKas) were determined by potentiometric titrations in NaCl solutions of various ionic strengths (I = 0.01-5.0 M), under inert nitrogen atmosphere at 25°C. Depending on the ionic strength, Ulva samples were manually titrated down to pH 2 or 3 with 1 N HCl and then up to pH 10 with 1 N NaOH in steps of 0.1-0.2 units, continuously monitoring pH with a glass combination electrode. Titrations of a dehydrated Ulva standard reference material (BCR-279) were compared with fresh Ulva tissue cultured in our laboratory. A titration in filtered natural seawater was also compared with one in an NaCl solution of equal ionic strength. Equilibrium constants for the ionization of water in NaCl solutions as a function of ionic strength were obtained from the literature. Fits to the titration data ([H]T vs. pH) were performed with the FITEQL4.0 computer code using non-electrostatic 3-, 4-, and 5-site models, either by fixing ionic strength at its experimental value or by allowing it to be extrapolated to zero, while considering all functional group pKas and bulk concentrations as adjustable parameters. Since pKas and bulk concentrations were found to be strongly correlated, the latter were also fixed in some cases to further constrain the pKas. Whereas these calculations are currently ongoing, preliminary results point to three, possibly four, functional groups with pKas of about 4.1, 6.3, and 9.5 at I = 0. Bulk concentrations of the three groups are very similar, about 5-6×10-4 mol/g based on dry weight, which suggests that all are homogeneously distributed over the surface and

  11. Distribution and pollution assessment of heavy metals in surface sediments in the Yellow Sea.

    PubMed

    Jiang, Xin; Teng, Ankang; Xu, Wenzhe; Liu, Xiaoshou

    2014-06-15

    Heavy metal concentrations in surface sediments at 56 stations during two cruises in the Yellow Sea in summer and winter, 2011 were analyzed by inductively coupled plasma-mass spectrometry. The pollution status was assessed via the Geoaccumulation index and Hankanson potential ecological risk index. Higher concentrations of heavy metals (except for Mn) were found in the central Southern Yellow Sea and the western Northern Yellow Sea. The higher contents of Mn were much closer to Shandong Peninsula. Correlation analyses indicated that Pb, Cu, Fe, Ni, Zn and Co probably had the same origin and were controlled by grain size and total organic carbon. Pollution assessment showed that most areas of the Yellow Sea were not or lowly contaminated with the exception of the northwest and south parts of the Southern Yellow Sea showing Cd-contamination. The pollution status of the Yellow Sea in summer was worse than that in winter.

  12. Evaluation of model simulated and MODIS-Aqua retrieved sea surface chlorophyll in the eastern Arabian Sea

    NASA Astrophysics Data System (ADS)

    Chakraborty, Kunal; Gupta, Anubhav; Lotliker, Aneesh A.; Tilstone, Gavin

    2016-11-01

    In this study we assess the accuracy of sea surface Chlorophyll-a (Chla) retrieved from satellite (MODIS-Aqua), using standard OC3M algorithm, and from a Regional Ocean Modelling System (ROMS) biophysical model against in situ data, measured in surface waters of the eastern Arabian Sea, from April 2009 to December 2012. MODIS-Aqua OC3M Chla concentrations showed a high correlation with the in situ data with slope close to unity and low root mean square error. In comparison, the ROMS model underestimated Chla, though the correlation was significant indicating that the model is capable of reproducing the trend in in situ Chla. Time Series trends in Chla were examined against wind driven Upwelling Indices (UIW) from April 2009 to December 2012 in north-eastern (Gujarat) and south-eastern (Kochi) coastal waters of the Arabian Sea. The annual peak in Chla along the Kochi coast during the summer monsoon was adequately captured by the model. It is well known that the peak in surface Chla along the Kochi and Gujarat coasts during the summer monsoon is the result of coastal upwelling, which the ROMS model was able to reproduce accurately. The maximum surface Chla along the Gujarat coast during the winter monsoon is due to convective mixing, which was also significantly captured by ROMS biophysical model. There was a lag of approximately one week between the maximum surface Chla and the peak in the Upwelling Index.

  13. Impact of surface roughness on L-band emissivity of the sea ice

    NASA Astrophysics Data System (ADS)

    Miernecki, M.; Kaleschke, L.; Hendricks, S.; Søbjærg, S. S.

    2015-12-01

    In March 2014 a joint experiment IRO2/SMOSice was carried out in the Barents Sea. R/V Lance equipped with meteorological instruments, electromagnetic sea ice thickness probe and engine monitoring instruments, was performing a series of tests in different ice conditions in order to validate the ice route optimization (IRO) system, advising on his route through pack ice. In parallel cal/val activities for sea ice thickness product obtained from SMOS (Soil Moisture and Ocean Salinity mission) L-band radiometer were carried out. Apart from helicopter towing the EMbird thickness probe, Polar 5 aircraft was serving the area during the experiment with L-band radiometer EMIRAD2 and Airborne Laser Scanner (ALS) as primary instruments. Sea ice Thickness algorithm using SMOS brightness temperature developed at University of Hamburg, provides daily maps of thin sea ice (up to 0.5-1 m) in polar regions with resolution of 35-50 km. So far the retrieval method was not taking into account surface roughness, assuming that sea ice is a specular surface. Roughness is a stochastic process that can be characterized by standard deviation of surface height σ and by shape of the autocorrelation function R to estimate it's vertical and horizontal scales respectively. Interactions of electromagnetic radiation with the surface of the medium are dependent on R and σ and they scales with respect to the incident wavelength. During SMOSice the radiometer was observing sea ice surface at two incidence angles 0 and 40 degrees and simultaneously the surface elevation was scanned with ALS with ground resolution of ~ 0.25 m. This configuration allowed us to calculate σ and R from power spectral densities of surface elevation profiles and quantify the effect of surface roughness on the emissivity of the sea ice. First results indicate that Gaussian autocorrelation function is suitable for deformed ice, for other ice types exponential function is the best fit.

  14. Proxy data constraints on Cretaceous sea surface temperature evolution

    NASA Astrophysics Data System (ADS)

    O'Brien, Charlotte L.; Robinson, Stuart A.; O'Connor, Lauren K.; Pancost, Richard D.

    2015-04-01

    It is well established that greenhouse conditions prevailed during the Cretaceous. However, constraining the exact nature of the greenhouse gas forcing, climatic warming and climate sensitivity remains an ongoing topic of research. Proxy temperature data provide valuable observational constraints on Cretaceous climate. In particular, much of our understanding of Cretaceous climate warmth comes from marine temperature proxy data reconstructions derived using planktic foraminiferal oxygen isotope (δ18O) palaeothermometry and, more recently, the TEX86 proxy, based on the distribution of marine isoprenoidal glycerol dialkyl glycerol tetraether lipids (GDGTs). Both of these proxies provide estimates of sea surface temperature (SST), however each technique is subject to a number of proxy-specific caveats. For example, δ18O values in planktic foraminifer may be compromised by preservation and/or diagenetic alteration, while the TEX86 proxy has undergone several temperature calibration re-evaluations and the exact mechanism that relates GDGT production to SST is not fully understood. Here we synthesise and reinterpret available TEX86- and δ18O-SST proxy data for the entire Cretaceous. For the TEX86 data, where possible we re-evaluate the fractional abundance of all individual GDGTs. By utilising fractional GDGT abundances we are also able to compute methane indices and branched and isoprenoid tetraether (BIT) indices, as well as apply both the TEX86H and TEX86L temperature calibrations. For each of the two SST proxy techniques, TEX86 and δ18O, we apply consistent temperature calibrations and place all data on a common timescale. Our new data-based SST synthesis allows us to examine long term temperature trends in the Cretaceous, including latitudinal temperature gradient variations, and evaluate global versus regional temperature patterns. Through considering both TEX86 and planktic foraminiferal δ18O data we critically compare the application of these two techniques

  15. Improving Streamflow Forecasts Using Predefined Sea Surface Temperature

    NASA Astrophysics Data System (ADS)

    Kalra, A.; Ahmad, S.

    2011-12-01

    With the increasing evidence of climate variability, water resources managers in the western United States are faced with greater challenges of developing long range streamflow forecast. This is further aggravated by the increases in climate extremes such as floods and drought caused by climate variability. Over the years, climatologists have identified several modes of climatic variability and their relationship with streamflow. These climate modes have the potential of being used as predictor in models for improving the streamflow lead time. With this as the motivation, the current research focuses on increasing the streamflow lead time using predefine climate indices. A data driven model i.e. Support Vector Machine (SVM) based on the statistical learning theory is used to predict annual streamflow volume 3-year in advance. The SVM model is a learning system that uses a hypothesis space of linear functions in a Kernel induced higher dimensional feature space, and is trained with a learning algorithm from the optimization theory. Annual oceanic-atmospheric indices, comprising of Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO), El Niño-Southern Oscillations (ENSO), and a new Sea Surface Temperature (SST) data set of "Hondo" Region for a period of 1906-2005 are used to generate annual streamflow volumes. The SVM model is applied to three gages i.e. Cisco, Green River, and Lees Ferry in the Upper Colorado River Basin in the western United States. Based on the performance measures the model shows very good forecasts, and the forecast are in good agreement with measured streamflow volumes. Previous research has identified NAO and ENSO as main drivers for extending streamflow forecast lead-time in the UCRB. Inclusion of "Hondo Region" SST information further improve the model's forecasting ability. The overall results of this study revealed that the annual streamflow of the UCRB is significantly influenced by

  16. Verification of Geosat sea surface topography in the Gulf Stream extension with surface drifting buoys and hydrographic measurements

    NASA Astrophysics Data System (ADS)

    Willebrand, J.; KäSe, R. H.; Stammer, D.; Hinrichsen, H.-H.; Krauss, W.

    1990-03-01

    Altimeter data from Geosat have been analyzed in the Gulf Stream extension area. Horizontal maps of the sea surface height anomaly relative to an annual mean for various 17-day intervals were constructed using an objective mapping procedure. The mean sea level was approximated by the dynamic topography from climatological hydrographic data. Geostrophic surface velocities derived from the composite maps (mean plus anomaly) are significantly correlated with surface drifter velocities observed during an oceanographie experiment in the spring of 1987. The drifter velocities contain much energy on scales less than 100 km which are not resolved in the altimetric maps. It is shown that the composite sea surface height also agrees well with ground verification from hydrographic data along sections in a triangle between the Azores, Newfoundland, and Bermuda, except in regions of high mean gradients.

  17. Antarctic Sea Ice Thickness From Surface Elevation: A Multi-Sensor Approach

    NASA Astrophysics Data System (ADS)

    Necsoiu, M.; Lewis, M. J.; Parra, J.; Ackley, S. F.; Weissling, B.; Hwang, B.

    2011-12-01

    Sea ice is an important component of the climate system affecting ocean-atmospheric interactions and global energy balance. The assessment of sea ice thickness using satellite and airborne laser altimetry is largely dependent upon isostatic buoyancy relationships between snow, ice, slush and ocean water. The use of these relationships in estimating sea ice thickness is complicated by a number of factors including spatial resolution, changing sea level reference, varying snow and ice density, and snow-ice interface flooding. Previous work has suggested that the effects of these factors can be reduced using a multi-sensor approach. The X-band backscatter from TerraSAR-X (TSX) is sensitive to surface roughness, snow and ice properties, and the presence of wet snow. The combined use of TSX for sea ice characterization and laser altimetry has the potential to provide more accurate estimates of sea ice thickness. In this study, we examine the feasibility of using TSX dual-polarized backscatter data to determine ice characteristics in the Bellingshausen and Amundsen Sea in the Antarctic region. Actual surface sea ice characteristics were derived from sea ice station measurements during the J.C. Ross (ICEBell) and Oden Southern Ocean (OSO) expeditions during the austral summer of 2010-11. Data from ice mass-balance buoys emplaced during the two cruises continued through summer melt and bridged the transition into fall freeze up conditions in the snow pack and ice cover. Shannon entropy derived from TSX, measures the statistical disorder of a medium illuminated by the radar, being a sum of two contributions related to intensity and the degree of polarization. A geostatistical approach is employed to correlate measured surface properties and sea ice freeboard with TSX-derived Shannon entropy. The floes are subsequently classified based on Shannon entropy and used in an empirically-based buoyancy model to estimate sea ice thickness. This approach is then compared with

  18. An atlas of monthly mean distributions of SSMI surface wind speed, AVHRR/2 sea surface temperature, AMI surface wind velocity, TOPEX/POSEIDON sea surface height, and ECMWF surface wind velocity during 1993

    NASA Technical Reports Server (NTRS)

    Halpern, D.; Fu, L.; Knauss, W.; Pihos, G.; Brown, O.; Freilich, M.; Wentz, F.

    1995-01-01

    The following monthly mean global distributions for 1993 are presented with a common color scale and geographical map: 10-m height wind speed estimated from the Special Sensor Microwave Imager (SSMI) on a United States (U.S.) Air Force Defense Meteorological Satellite Program (DMSP) spacecraft; sea surface temperature estimated from the Advanced Very High Resolution Radiometer (AVHRR/2) on a U.S. National Oceanic and Atmospheric Administration (NOAA) satellite; 10-m height wind speed and direction estimated from the Active Microwave Instrument (AMI) on the European Space Agency (ESA) European Remote Sensing (ERS-1) satellite; sea surface height estimated from the joint U.S.-France Topography Experiment (TOPEX)/POSEIDON spacecraft; and 10-m height wind speed and direction produced by the European Center for Medium-Range Weather Forecasting (ECMWF). Charts of annual mean, monthly mean, and sampling distributions are displayed.

  19. A 30-day forecast experiment with the GISS model and updated sea surface temperatures

    NASA Technical Reports Server (NTRS)

    Spar, J.; Atlas, R.; Kuo, E.

    1975-01-01

    The GISS model was used to compute two parallel global 30-day forecasts for the month January 1974. In one forecast, climatological January sea surface temperatures were used, while in the other observed sea temperatures were inserted and updated daily. A comparison of the two forecasts indicated no clear-cut beneficial effect of daily updating of sea surface temperatures. Despite the rapid decay of daily predictability, the model produced a 30-day mean forecast for January 1974 that was generally superior to persistence and climatology when evaluated over either the globe or the Northern Hemisphere, but not over smaller regions.

  20. Effect of atmospheric radiance errors in radiometric sea-surface skin temperature measurements.

    PubMed

    Donlon, C J; Nightingale, T J

    2000-05-20

    Errors in measurements of sea-surface skin temperature (SSST) caused by inappropriate measurements of sky radiance are discussed; both model simulations and in situ data obtained in the Atlantic Ocean are used. These errors are typically caused by incorrect radiometer view geometry (pointing), temporal mismatches between the sea surface and atmospheric views, and the effect of wind on the sea surface. For clear-sky, overcast, or high-humidity atmospheric conditions, SSST is relatively insensitive (<0.1 K) to sky-pointing errors of ?10 degrees and to temporal mismatches between the sea and sky views. In mixed-cloud conditions, SSST errors greater than ?0.25 K are possible as a result either of poor radiometer pointing or of a temporal mismatch between the sea and sky views. Sea-surface emissivity also changes with sea view pointing angle. Sea view pointing errors should remain below 5 degrees for SSST errors of <0.1 K. We conclude that the clear-sky requirement of satellite infrared SSST observations means that sky-pointing errors are small when one is obtaining in situ SSST validation data at zenith angles of <40 degrees . At zenith angles greater than this, large errors are possible in high-wind-speed conditions. We recommend that high-resolution inclinometer measurements always be used, together with regular alternating sea and sky views, and that the temporal mismatch between sea and sky views be as small as possible. These results have important implications for the development of operational autonomous instruments for determining SSST for the long-term validation of satellite SSST.

  1. Video system for monitoring sea-surface characteristics in coastal zone

    NASA Astrophysics Data System (ADS)

    Konstantinov, Oleg G.; Pavlov, Andrey N.

    2012-11-01

    A method of investigation sea surface roughness by analysis polarization images is suggested. Equipment and software were developed and tested at the Pacific Oceanological Institute (POI) It is shown a possibility to study surface manifestations of hydrodynamic processes in coastal zone, such as the dynamics of vortex structures, internal waves, spatio-temporal properties of surface waves by using the panoramic video system for a sea surface control and by the imaging polarimeter. Analysis of a time sequence of transformed to the plane panoramic images obtained using the system allows to estimate a velocity field of vortex structure, phase velocity of surface manifestations of internal waves, intensity and dynamics of surface films of oil pollution. It is shown an ability of sea surface reconstruction by analyzing time sequence of the imaging polarimeter pictures. The results are compared with the height difference of the floats located on the vertical guides that are in the imaging polarimeter field of view. The float heights obtained from its image coordinates. Field experiments were conducted at the POI marine station in the Japan Sea. Moreover, the developed methods and equipment may be used as a source of unique in situ information on the sea surface roughness during satellite optical and radar sensing.

  2. Large contribution of sea surface warming to recent increase in Atlantic hurricane activity.

    PubMed

    Saunders, Mark A; Lea, Adam S

    2008-01-31

    Atlantic hurricane activity has increased significantly since 1995 (refs 1-4), but the underlying causes of this increase remain uncertain. It is widely thought that rising Atlantic sea surface temperatures have had a role in this, but the magnitude of this contribution is not known. Here we quantify this contribution for storms that formed in the tropical North Atlantic, Caribbean Sea and Gulf of Mexico; these regions together account for most of the hurricanes that make landfall in the United States. We show that a statistical model based on two environmental variables--local sea surface temperature and an atmospheric wind field--can replicate a large proportion of the variance in tropical Atlantic hurricane frequency and activity between 1965 and 2005. We then remove the influence of the atmospheric wind field to assess the contribution of sea surface temperature. Our results indicate that the sensitivity of tropical Atlantic hurricane activity to August-September sea surface temperature over the period we consider is such that a 0.5 degrees C increase in sea surface temperature is associated with a approximately 40% increase in hurricane frequency and activity. The results also indicate that local sea surface warming was responsible for approximately 40% of the increase in hurricane activity relative to the 1950-2000 average between 1996 and 2005. Our analysis does not identify whether warming induced by greenhouse gases contributed to the increase in hurricane activity, but the ability of climate models to reproduce the observed relationship between hurricanes and sea surface temperature will serve as a useful means of assessing whether they are likely to provide reliable projections of future changes in Atlantic hurricane activity.

  3. Processes controlling surface, bottom and lateral melt of Arctic sea ice in a state of the art sea ice model.

    PubMed

    Tsamados, Michel; Feltham, Daniel; Petty, Alek; Schroeder, David; Flocco, Daniela

    2015-10-13

    We present a modelling study of processes controlling the summer melt of the Arctic sea ice cover. We perform a sensitivity study and focus our interest on the thermodynamics at the ice-atmosphere and ice-ocean interfaces. We use the Los Alamos community sea ice model CICE, and additionally implement and test three new parametrization schemes: (i) a prognostic mixed layer; (ii) a three equation boundary condition for the salt and heat flux at the ice-ocean interface; and (iii) a new lateral melt parametrization. Recent additions to the CICE model are also tested, including explicit melt ponds, a form drag parametrization and a halodynamic brine drainage scheme. The various sea ice parametrizations tested in this sensitivity study introduce a wide spread in the simulated sea ice characteristics. For each simulation, the total melt is decomposed into its surface, bottom and lateral melt components to assess the processes driving melt and how this varies regionally and temporally. Because this study quantifies the relative importance of several processes in driving the summer melt of sea ice, this work can serve as a guide for future research priorities.

  4. Emiliania huxleyi Goes Viral: Dynamic Variation of Intact Polar Lipids and Alkenones

    NASA Astrophysics Data System (ADS)

    Fulton, J. M.; Fredricks, H.; Vardi, A.; DiTullio, G. R.; Bidle, K. D.; Van Mooy, B.

    2012-12-01

    Viruses are an important component of marine ecosystems, shunting more than 25% of the organic carbon in algal biomass away from grazers to the dissolved organic carbon pool, fueling microbial foodwebs. Virus infection has long been implicated in the termination of Emiliania huxleyi blooms, and recent work demonstrated that EhV86, the type virus of E. huxleyi, is bound by a lipid membrane and employs an animal-like infection strategy, similar to the human immunodeficiency virus (HIV). We add to this story by quantifying EhV86 and host (Ehux374) lipodomes before, during, and after infection in laboratory culture. We identified novel intact polar lipids (IPLs), and based on their structures and experimental results, we hypothesize that they are dynamic players in cell-virus interactions, not just structural membrane components. Alkenones also have an apparent role in viral infection as they are part of the EhV86 lipidome, their production increases during infection, and growth temperatures calculated from alkenone unsaturation in infected cultures are elevated relative to uninfected cultures. EhV86 carries genes for glycosphingolipid (GSL) synthesis, and production increases exponentially during infection, leading to a ca. 100-fold increase in GSL concentration per cell. We hypothesize that specific GSLs (1) promote viral attachment via a sialic acid headgroup and (2) induce programmed cell death and lysis. In response to infection, Ehux374 produces a diacylglycerolipid with a myriocin-like (ML) structure that inhibits GSL synthesis. Remarkably, the EhV86 lipidome contains an abundant ML, but with a different fatty acid distribution that apparently neutralizes its effect on the GSL synthesis pathway. The neutralized ML lipid is also common in lipid extracts from the North Atlantic, suggesting it may be found in other organisms as well. We propose that much of the lipid variability during infection occurs in lipid rafts, microdomains in the plasma membrane targeted by

  5. Last Glacial Maximum sea surface temperature and sea-ice extent in the Pacific sector of the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Benz, Verena; Esper, Oliver; Gersonde, Rainer; Lamy, Frank; Tiedemann, Ralf

    2016-08-01

    Sea surface temperatures and sea-ice extent are most critical variables to evaluate the Southern Ocean paleoceanographic evolution in relation to the development of the global carbon cycle, atmospheric CO2 and ocean-atmosphere circulation. Here we present diatom transfer function-based summer sea surface temperature (SSST) and winter sea-ice (WSI) estimates from the Pacific sector of the Southern Ocean to bridge a gap in information that has to date hampered a well-established reconstruction of the last glacial Southern Ocean at circum-Antarctic scale. We studied the Last Glacial Maximum (LGM) at the EPILOG time slice (19,000-23,000 calendar years before present) in 17 cores and consolidated our LGM picture of the Pacific sector taking into account published data from its warmer regions. Our data display a distinct east-west differentiation with a rather stable WSI edge north of the Pacific-Antarctic Ridge in the Ross Sea sector and a more variable WSI extent over the Amundsen Abyssal Plain. The zone of maximum cooling (>4 K) during the LGM is in the present Subantarctic Zone and bounded to its south by the 4 °C isotherm. The isotherm is in the SSST range prevailing at the modern Antarctic Polar Front, representing a circum-Antarctic feature, and marks the northern edge of the glacial Antarctic Circumpolar Current (ACC). The northward deflection of colder than modern surface waters along the South American continent led to a significant cooling of the glacial Humboldt Current surface waters (4-8 K), which affected the temperature regimes as far north as tropical latitudes. The glacial reduction of ACC temperatures may also have resulted in significant cooling in the Atlantic and Indian Southern Ocean, thus enhancing thermal differentiation of the Southern Ocean and Antarctic continental cooling. The comparison with numerical temperature and sea-ice simulations yields discrepancies, especially concerning the estimates of the sea-ice fields, but some simulations

  6. Holocene sea subsurface and surface water masses in the Fram Strait - Comparisons of temperature and sea-ice reconstructions

    NASA Astrophysics Data System (ADS)

    Werner, Kirstin; Müller, Juliane; Husum, Katrine; Spielhagen, Robert F.; Kandiano, Evgenia S.; Polyak, Leonid

    2016-09-01

    Two high-resolution sediment cores from eastern Fram Strait have been investigated for sea subsurface and surface temperature variability during the Holocene (the past ca 12,000 years). The transfer function developed by Husum and Hald (2012) has been applied to sediment cores in order to reconstruct fluctuations of sea subsurface temperatures throughout the period. Additional biomarker and foraminiferal proxy data are used to elucidate variability between surface and subsurface water mass conditions, and to conclude on the Holocene climate and oceanographic variability on the West Spitsbergen continental margin. Results consistently reveal warm sea surface to subsurface temperatures of up to 6 °C until ca 5 cal ka BP, with maximum seawater temperatures around 10 cal ka BP, likely related to maximum July insolation occurring at that time. Maximum Atlantic Water (AW) advection occurred at surface and subsurface between 10.6 and 8.5 cal ka BP based on both foraminiferal and dinocyst temperature reconstructions. Probably, a less-stratified, ice-free, nutrient-rich surface ocean with strong AW advection prevailed in the eastern Fram Strait between 10 and 9 cal ka BP. Weakened AW contribution is found after ca 5 cal ka BP when subsurface temperatures strongly decrease with minimum values between ca 4 and 3 cal ka BP. Cold late Holocene conditions are furthermore supported by high planktic foraminifer shell fragmentation and high δ18O values of the subpolar planktic foraminifer species Turborotalita quinqueloba. While IP25-associated indices as well as dinocyst data suggest a sustained cooling due to a decrease in early summer insolation and consequently sea-ice increase since about 7 cal ka BP in surface waters, planktic foraminiferal data including stable isotopes indicate a slight return of stronger subsurface AW influx since ca 3 cal ka BP. The observed decoupling of surface and subsurface waters during the later Holocene is most likely attributed to a strong

  7. Trophic dynamics of deep-sea megabenthos are mediated by surface productivity.

    PubMed

    Tecchio, Samuele; van Oevelen, Dick; Soetaert, Karline; Navarro, Joan; Ramírez-Llodra, Eva

    2013-01-01

    Most deep-sea benthic ecosystems are food limited and, in the majority of cases, are driven by the organic matter falling from the surface or advected downslope. Species may adapt to this scarceness by applying a wide variety of responses, such as feeding specialisation, niche width variation, and reduction in metabolic rates. The Mediterranean Sea hosts a gradient of food availability at the deep seafloor over its wide longitudinal transect. In the Mediterranean, broad regional studies on trophic habits are almost absent, and the response of deep-sea benthos to different trophic conditions is still speculative. Here, we show that both primary and secondary production processes taking place at surface layers are key drivers of deep-sea food web structuring. By employing an innovative statistical tool, we interpreted bulk-tissue δ(13)C and δ(15)N isotope ratios in benthic megafauna, and associated surface and mesopelagic components from the 3 basins of the Mediterranean Sea at 3 different depths (1200, 2000, and 3000 m). The trophic niche width and the amplitude of primary carbon sources were positively correlated with both primary and secondary surface production indicators. Moreover, mesopelagic organic matter utilization processes showed an intermediate position between surface and deep benthic components. These results shed light on the understanding of deep-sea ecosystems functioning and, at the same time, they demand further investigation.

  8. Sound scattering from rough bubbly ocean surface based on modified sea surface acoustic simulator and consideration of various incident angles and sub-surface bubbles' radii

    NASA Astrophysics Data System (ADS)

    Bolghasi, Alireza; Ghadimi, Parviz; Chekab, Mohammad A. Feizi

    2016-09-01

    The aim of the present study is to improve the capabilities and precision of a recently introduced Sea Surface Acoustic Simulator (SSAS) developed based on optimization of the Helmholtz-Kirchhoff-Fresnel (HKF) method. The improved acoustic simulator, hereby known as the Modified SSAS (MSSAS), is capable of determining sound scattering from the sea surface and includes an extended Hall-Novarini model and optimized HKF method. The extended Hall-Novarini model is used for considering the effects of sub-surface bubbles over a wider range of radii of sub-surface bubbles compared to the previous SSAS version. Furthermore, MSSAS has the capability of making a three-dimensional simulation of scattered sound from the rough bubbly sea surface with less error than that of the Critical Sea Tests (CST) experiments. Also, it presents scattered pressure levels from the rough bubbly sea surface based on various incident angles of sound. Wind speed, frequency, incident angle, and pressure level of the sound source are considered as input data, and scattered pressure levels and scattering coefficients are provided. Finally, different parametric studies were conducted on wind speeds, frequencies, and incident angles to indicate that MSSAS is quite capable of simulating sound scattering from the rough bubbly sea surface, according to the scattering mechanisms determined by Ogden and Erskine. Therefore, it is concluded that MSSAS is valid for both scattering mechanisms and the transition region between them that are defined by Ogden and Erskine.

  9. Sound scattering from rough bubbly ocean surface based on modified sea surface acoustic simulator and consideration of various incident angles and sub-surface bubbles' radii

    NASA Astrophysics Data System (ADS)

    Bolghasi, Alireza; Ghadimi, Parviz; Chekab, Mohammad A. Feizi

    2016-08-01

    The aim of the present study is to improve the capabilities and precision of a recently introduced Sea Surface Acoustic Simulator (SSAS) developed based on optimization of the Helmholtz-Kirchhoff-Fresnel (HKF) method. The improved acoustic simulator, hereby known as the Modified SSAS (MSSAS), is capable of determining sound scattering from the sea surface and includes an extended Hall-Novarini model and optimized HKF method. The extended Hall-Novarini model is used for considering the effects of sub-surface bubbles over a wider range of radii of sub-surface bubbles compared to the previous SSAS version. Furthermore, MSSAS has the capability of making a three-dimensional simulation of scattered sound from the rough bubbly sea surface with less error than that of the Critical Sea Tests (CST) experiments. Also, it presents scattered pressure levels from the rough bubbly sea surface based on various incident angles of sound. Wind speed, frequency, incident angle, and pressure level of the sound source are considered as input data, and scattered pressure levels and scattering coefficients are provided. Finally, different parametric studies were conducted on wind speeds, frequencies, and incident angles to indicate that MSSAS is quite capable of simulating sound scattering from the rough bubbly sea surface, according to the scattering mechanisms determined by Ogden and Erskine. Therefore, it is concluded that MSSAS is valid for both scattering mechanisms and the transition region between them that are defined by Ogden and Erskine.

  10. Simulation of a polarized laser beam reflected at the sea surface: modeling and validation

    NASA Astrophysics Data System (ADS)

    Schwenger, Frédéric

    2015-05-01

    A 3-D simulation of the polarization-dependent reflection of a Gaussian shaped laser beam on the dynamic sea surface is presented. The simulation considers polarized or unpolarized laser sources and calculates the polarization states upon reflection at the sea surface. It is suitable for the radiance calculation of the scene in different spectral wavebands (e.g. near-infrared, SWIR, etc.) not including the camera degradations. The simulation also considers a bistatic configuration of laser source and receiver as well as different atmospheric conditions. In the SWIR, the detected total power of reflected laser light is compared with data collected in a field trial. Our computer simulation combines the 3-D simulation of a maritime scene (open sea/clear sky) with the simulation of polarized or unpolarized laser light reflected at the sea surface. The basic sea surface geometry is modeled by a composition of smooth wind driven gravity waves. To predict the input of a camera equipped with a linear polarizer, the polarized sea surface radiance must be calculated for the specific waveband. The s- and p-polarization states are calculated for the emitted sea surface radiance and the specularly reflected sky radiance to determine the total polarized sea surface radiance of each component. The states of polarization and the radiance of laser light specularly reflected at the wind-roughened sea surface are calculated by considering the s- and p- components of the electric field of laser light with respect to the specular plane of incidence. This is done by using the formalism of their coherence matrices according to E. Wolf [1]. Additionally, an analytical statistical sea surface BRDF (bidirectional reflectance distribution function) is considered for the reflection of laser light radiances. Validation of the simulation results is required to ensure model credibility and applicability to maritime laser applications. For validation purposes, field measurement data (images and

  11. Increasing positive trend in the Antarctic sea ice extent and associated surface temperature changes

    NASA Astrophysics Data System (ADS)

    Comiso, J. C.

    2015-12-01

    The maximum extent of the Antarctic sea ice in 2014 was more than 20 x 106 km2 which is likely the highest during the satellite era. The updated historical record of the sea ice cover, as derived from multichannel passive microwave data, now shows a trend of 2.05 ± 0.18% per decade and 2.70 ± 0.20 % per decade for ice extent and ice area, respectively. This indicates not only a continuation of the positive trend but also a slight increase in the trends reported previously. A newly enhanced sea ice concentration data actually yield slightly more modest trends in the sea ice extent and ice area of 1.55 ± 0.17 % per decade and 2.40 ± 0.20 % per decade, respectively. The difference is mainly due to an improved matching of calibrations in the enhanced data for the different satellite sensors that provide the historical time series. The updated data also show regional shifts in the trends with a decrease in the positive trend in the Ross Sea, a decrease in the negative trend in the Bellingshausen/Amundsen Seas, and an increase in the positive trend in the other sectors. Such shifts undermine the previous hypothesis that the positive trend of Antarctic sea ice is primarily caused by increases in ice production in the Ross Sea. On the other hand, it is observed that surface temperatures for the same period, as derived from satellite data, show a general cooling in areas near the ice margin. Surface temperatures are also shown to be highly correlated with the extent of the sea ice cover. Such results suggests that the assimilation of satellite surface temperature data in numerical climate models may be needed to improve the performance of these models and enable better agreements with the observed trends of sea ice in the Southern Hemisphere.

  12. Sea surface height variability in the North East Atlantic from satellite altimetry

    NASA Astrophysics Data System (ADS)

    Sterlini, Paul; de Vries, Hylke; Katsman, Caroline

    2016-08-01

    Data from 21 years of satellite altimeter measurements are used to identify and understand the major contributing components of sea surface height variability (SSV) on monthly time-scales in the North East Atlantic. A number of SSV drivers is considered, which are categorised into two groups; local (wind and sea surface temperature) and remote (sea level pressure and the North Atlantic oscillation index). A multiple linear regression model is constructed to model the SSV for a specific target area in the North Sea basin. Cross-correlations between candidate regressors potentially lead to ambiguity in the interpretation of the results. We therefore use an objective hierarchical selection method based on variance inflation factors to select the optimal number of regressors for the target area and accept these into the regression model if they can be associated to SSV through a direct underlying physical forcing mechanism. Results show that a region of high SSV exists off the west coast of Denmark and that it can be represented well with a regression model that uses local wind, sea surface temperature and sea level pressure as primary regressors. The regression model developed here helps to understand sea level change in the North East Atlantic. The methodology is generalised and easily applied to other regions.

  13. Biweekly Sea Surface Temperature over the South China Sea and its association with the Western North Pacific Summer Monsoon

    NASA Astrophysics Data System (ADS)

    Vaid, B. H.

    2015-10-01

    The association of the biweekly intraseasonal (BWI) oscillation in the Sea Surface Temperature (SST) over the South China Sea (SCS) and the Western North Pacific Summer Monsoon is authenticated using version 4 the Tropical Rainfall Measuring Mission Microwave Imager data (SST and rain) and heat fluxes from Ocean Atmosphere Flux project data during 1998-2012. The results suggest that the SCS involves ocean-atmosphere coupling on biweekly timescales. The positive biweekly SST anomalies lead the rain anomalies over the SCS by 3 days, with a significant correlation coefficient (r = 0.6, at 99 % significance levels) between the SST-rain anomalies. It is evident from lead/lag correlation between biweekly SST and zonal wind shear that warm ocean surface induced by wind shear may contribute to a favorable condition of the convective activity over the SCS. The present study suggests that ocean-to-atmospheric processes induced by the BWI oscillation in the SCS SST results in enhanced sea level pressure and surface shortwave radiation flux during the summer monsoon. Besides, it is observed that the SCS BWI oscillation in the changes of SST causes a feedback in the atmosphere by modifying the atmospheric instability. This suggests that the active/break biweekly cycle of the SST over the SCS is related by sea level pressure, surface heat fluxes and atmospheric instability. The potential findings here indicate that the biweekly SST over the SCS play an important role in the eastward and the southward propagation of the biweekly anomalies in the Western North Pacific.

  14. The organic sea surface microlayer in the upwelling region off Peru and implications for air-sea exchange processes

    NASA Astrophysics Data System (ADS)

    Engel, A.; Galgani, L.

    2015-07-01

    The sea surface microlayer (SML) is at the very surface of the ocean, linking the hydrosphere with the atmosphere, and central to a range of global biogeochemical and climate-related processes. The presence and enrichment of organic compounds in the SML have been suggested to influence air-sea gas exchange processes as well as the emission of primary organic aerosols. Among these organic compounds, primarily of plankton origin, are dissolved exopolymers, specifically polysaccharides and proteins, and gel particles, such as Transparent Exopolymer Particles (TEP) and Coomassie Stainable Particles (CSP). These organic substances often accumulate in the surface ocean when plankton productivity is high. Here, we report results obtained in December 2012 during the SOPRAN Meteor 91 cruise to the highly productive, coastal upwelling regime off Peru. Samples were collected from the SML and from ~ 20 cm below, and were analyzed for polysaccharidic and proteinaceous compounds, gel particles, total and dissolved organic carbon, bacterial and phytoplankton abundance. Our study provides insight to the physical and biological control of organic matter enrichment in the SML, and discusses the potential role of organic matter in the SML for air-sea exchange processes.

  15. Control of lithosphere structure on surface deformation in the Central Barents Sea: insights from dynamical modeling

    NASA Astrophysics Data System (ADS)

    Gac, Sebastien; Faleide, Jan Inge

    2014-05-01

    The Barents Sea is located in the Northern European Arctic. The Eastern Barents Sea features one of the deepest sedimentary basins in the world whereas large parts of the Western Barents Sea is covered by a shallow sedimentary platform. Seismic tomography data (Levshin et al., 2007; Ritzmann and Faleide, 2009) show slower S-wave velocity in the upper mantle beneath the East Barents Sea compared to the West Barents Sea, indicating a steep deepening of the Lithosphere-Asthenosphere Boundary (LAB) in the Central Barents Sea from West to East. Additionally, the Central Barents Sea is marked by a South-North succession of regularly-spaced inverted structures (uplifted domes) such as the Fedinsky High and the Sentralbanken High. The origin of these inverted structures is under debate. The interpretation of recent seismic data in the Central Barents Sea suggests that part of the inversion is contemporaneous with the Late-Triassic-Early Jurassic westwards thrusting of Novaya Zemlya. This suggests that the origin of domes might be linked to compressional events on the eastern side of the Barents Sea. A 2D thermo-mechanical model of lithosphere shortening is used to explore the effect of LAB geometry on the surface deformation in the Central Barents Sea. The model is based on a Lagrangian finite element method (Gac et al., 2013). The model consists of a crust - mantle lithosphere characterized by non-linear temperature and pressure dependent visco-elastic-plastic rheologies. The mechanical model is coupled with a thermal model taking into account heat advection and diffusion. Sedimentation and gravity are also taken into account. Contractional boundary conditions are applied on vertical sides of the model resulting in buckling of the crust. Several models are run for different geometry of the LAB. Preliminary results are shown. 3D conceptual models are then proposed to explain the 3D distribution of inverted structures in the Central Barents Sea. REFERENCES: Gac, S

  16. Reconstructing Variations of Global Sea-Surface Temperature during the Last Interglaciation

    NASA Astrophysics Data System (ADS)

    Hoffman, J. S.; Clark, P. U.; He, F.; Parnell, A. C.

    2015-12-01

    The last interglaciation (LIG; ~130-116 ka) was the most recent period in Earth history with higher-than-present global sea level (≥6 m) under similar-to-preindustrial concentrations of atmospheric CO2, suggesting additional feedbacks related to albedo, insolation, and ocean circulation in generating the apparent climatic differences between the LIG and present Holocene. However, our understanding of how much warmer the LIG sea surface was relative to the present interglaciation remains uncertain, with current estimates suggesting from 0°C to 2°C warmer than late-20thcentury average global temperatures. Moreover, the timing, spatial expression, and amplitude of regional and global sea surface temperature variability related to other climate forcing during the LIG are poorly constrained, largely due to uncertainties in age control and proxy temperature reconstructions. An accurate characterization of global and regional temperature change during the LIG can serve as a benchmark for paleoclimate modeling intercomparison projects and help improve understanding of sea-level sensitivity to temperature change. We will present a global compilation (~100 published records) of sea surface temperature (SST) and other climate reconstructions spanning the LIG. Using a Monte Carlo-enabled cross-correlation maximization algorithm to climatostratigraphically align proxy records and then account for both the resulting chronologic and proxy calibration uncertainties with Bayesian statistical inference, our results quantify the spatial timing, amplitude, and uncertainty in estimates of global and regional sea surface temperature change during the LIG and its relation to potential forcings.

  17. Emissivity of rough sea surface for 8-13 num: modeling and verification.

    PubMed

    Wu, X; Smith, W L

    1997-04-20

    The emissivity model for rough sea surface [Remote Sensing Environ. 24, 313-329 (1988)] is inspected in light of the measured surface emissivity. In the presence of moderate wind (5 m/s or less), the emissivity model is found to be adequate for small to moderate view angles. For large view angles, the discrepancy between the computed and the measured emissivity is large, but one can reduce this considerably by incorporating the reflected sea surface emission into the emissivity model. In addition, examination of the spectral variation of the observed and computed emissivity suggests the need for refined measurements of the complex refractive index. An improved model is constructed to calculate the rough sea surface emissivity that can be used to provide accurate estimates of sea surface skin temperatures from remotely sensed radiometric measurements. An important feature of the improved model is that the computed sea surface emissivity is only weakly dependent on wind speed for most view angles used in practice.

  18. Sea, ice and surface water circulation, Alaskan continental shelf

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    The author has identified the following significant results. Salinity and temperature measurements in the Bering Sea indicate that the Yukon River outflow extends as far as 200 km from its mouth. The fresh water flow from the Yukon River flows north and east into Norton Sound. Various levels of suspended sediment concentration in waters have been successfully color coded using a VP-8 color density slicing image analyzer. The 70 mm negative transparencies have provided the best fit for the ground truth observations.

  19. On the effect of sea spray on the aerodynamic surface drag under severe winds

    NASA Astrophysics Data System (ADS)

    Troitskaya, Yuliya; Ezhova, Ekaterina; Soustova, Irina; Zilitinkevich, Sergej

    2016-05-01

    We investigate the effect of the sea spray on the air-sea momentum exchange during the entire "life cycle" of a droplet, torn off the crest of a steep surface wave, and its fall down to the water, in the framework of a model covering the following aspects of the phenomenon: (1) motion of heavy particle in the driving air flow (equations of motion); (2) structure of the wind field (wind velocity, wave-induced disturbances, turbulent fluctuations); (3) generation of the sea spray; and (4) statistics of droplets (size distribution, wind speed dependence). It is demonstrated that the sea spray in strong winds leads to an increase in the surface drag up to 40 % on the assumption that the velocity profile is neutral.

  20. Reconstructing Holocene sea surface salinity changes in the Northern Aegean Sea: evidence from morphological variations of Emiliania huxleyi-coccoliths

    NASA Astrophysics Data System (ADS)

    Herrle, Jens O.; Gebühr, Christina; Bollmann, Jörg; Giesenberg, Annika; Kranzdorf, Philip

    2013-04-01

    The Aegean Sea is a key area for our understanding of the impact of changes in the hydrological cycle on ocean circulation in the Mediterranean Sea. The Aegean Sea appears to be very sensitive to climate changes in Europe because of its small volume and the position between high- and low-latitude climate regimes. Therefore, it is assumed to record environmental change, especially changes in sea surface water salinity (SSS) without a significant time lag with respect to the forcing process (Rohling et al., 2002). However, up to date, SSS cannot be easily reconstructed from geological archives because several assumptions need to be made that lead to a significant error of the salinity estimates (e.g. Rohling, 2000). Here, we present the first high resolution SSS reconstruction from a Holocene sediment core based on a recently developed transfer function using the morphological variation of Emiliania huxleyi coccoliths (Bollmann & Herrle 2007, Bollmann et al., 2009). The core is located in the northern Aegean Sea (eastern Mediterranean Basin) and covers the time period 3 -11ka ago. Sea surface water salinity in the Aegean Sea has varied in concert with temperature oscillations as recorded in Greenland ice cores (iGISP2 ice core δ18O record) with a periodicity of about 900 years (Schulz & Paull, 2002). Four major SSS events can be identified at about 3.9, 4.7, 6.4, 7.4, and 8.2 ka in the northern Aegean Sea that correlate with increases in GISP2 δ18O (Schulz & Paull, 2002) as well as decreasing percentages of tree pollen studied at the same core expect for 3.9 ka (Kotthoff et al., 2008). The most prominent salinity increase occurred during the short-lived 8.2 kyr cold event (e.g., Rohling & Pälike, 2005), which was most likely triggered by a melt-water related perturbation of the Atlantic Meridional Overturning and associated decrease of ocean heat transport to the North Atlantic. We suggest that the salinity fluctuations in the northern Aegean Sea are related to

  1. Aerosol-cloud-land surface interactions within tropical sea breeze convection

    NASA Astrophysics Data System (ADS)

    Grant, Leah D.; Heever, Susan C.

    2014-07-01

    In this study, the influence of aerosols, surface roughness length, soil moisture, and synergistic interactions among these factors on tropical convective rainfall focused along a sea breeze front are explored within idealized cloud-resolving modeling simulations using the Regional Atmospheric Modeling System (RAMS). The idealized RAMS domain setup is representative of the coastal Cameroon rainforest in equatorial Africa. In order to assess the potential sensitivity of sea breeze convection to increasing anthropogenic activity and deforestation occurring in such regions, 27 total simulations are performed in which combinations of enhanced aerosol concentrations, reduced surface roughness length, and reduced soil moisture are included. Both enhanced aerosols and reduced soil moisture are found to individually reduce the precipitation due to reductions in downwelling shortwave radiation and surface latent heat fluxes, respectively, while perturbations to the roughness length do not have a large impact on the precipitation. The largest soil moisture perturbations dominate the precipitation changes due to reduced low-level moisture available to the convection, but if the soil moisture perturbation is more moderate, synergistic interactions between soil moisture and aerosols enhance the sea breeze precipitation. This is found to result from evening convection that forms ahead of the sea breeze only when both effects are present. Interactions between the resulting gust fronts and the sea breeze front locally enhance convergence and therefore the rainfall. The results of this study underscore the importance of considering the aerosol-cloud-land surface system responses to perturbations in aerosol loading and land surface characteristics.

  2. Impact of Typhoon-induced sea surface cooling on the track of next Typhoon

    NASA Astrophysics Data System (ADS)

    Ando, Y.; Horiguchi, M.; Kodera, K.; Tachibana, Y.; Yamazaki, K.

    2015-12-01

    Typhoons (TCs) MATMO, HALONG, and NAKRI (2014), which caused Japan catastrophic disaster, landed the western part of Japan. The TCs came to Japan one after another during late July to early August 2014. The tracks of these TCs were similar, i.e., the TCs followed the western edge of the subtropical northwestern Pacific high (SNPH). However, the tracks gradually reached to Japan, which were associated with weakening the westward expansion of the SNPH. It was found that the changes in westward expansion of the SNPH were associated with TC-induced sea surface cooling of previous Typhoon. It has previously been reported that TC-induced sea surface cooling is mainly caused by Ekman upwelling and vertical turbulent mixing. The TCs MATMO, HALONG, and NAKRI passed around the Philippines, and induced sea surface cooling of this area. The sea surface temperatures of this area are important for Pacific-Japan pattern, which was associated with the westward expansion of the SNPH. Consequently, previous Typhoon induced sea surface cooling around the Philippines, which weakening the westward expansion of the SNPH. Then, the tracks of next Typhoon were changed, and gradually reached to Japan.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The observed changes in physical properties of sea ice such as decreased thickness and increased melt pond cover severely impact the energy balance of Arctic sea ice. Increased light transmission leads to increased deposition of solar energy and thus plays a crucial role for sea-ice-melt as well as for the amount and timing of under-ice primary production. Recent developments in underwater technology provide new opportunities to undertake challenging research at the largely inaccessible underside of sea ice. We measured spectral under-ice radiance and irradiance onboard the new Nereid Under-Ice (Nereid-UI) underwater robotic vehicle, during a cruise of the R/V Polarstern to 83°N 6°W in the Arctic Ocean in July 2014. Nereid-UI is a next generation hybrid remotely operated vehicle (H-ROV) designed for both remotely-piloted and autonomous surveys underneath fixed and moving sea ice. Here we present results from the first comprehensive scientific dive of Nereid-UI employing its interdisciplinary sensor suite. We combine under-ice optical measurements with three dimensional under-ice topography (multibeam sonar) and aerial images of the surface conditions. We investigate the influence of spatially varying ice-thickness and surface properties on the spatial variability of light transmittance on floe scale. Our results indicate that surface properties dominate the spatial distribution of the under-ice light field, while sea ice-thickness and snow-depth are most important for mean light levels.

  4. Simple heterogeneity parametrization for sea surface temperature and chlorophyll

    NASA Astrophysics Data System (ADS)

    Skákala, Jozef; Smyth, Timothy J.

    2016-06-01

    Using satellite maps this paper offers a complex analysis of chlorophyll & SST heterogeneity in the shelf seas around the southwest of the UK. The heterogeneity scaling follows a simple power law and is consequently parametrized by two parameters. It is shown that in most cases these two parameters vary only relatively little with time. The paper offers a detailed comparison of field heterogeneity between different regions. How much heterogeneity is in each region preserved in the annual median data is also determined. The paper explicitly demonstrates how one can use these results to calculate representative measurement area for in situ networks.

  5. Surfactant-Associated Bacteria in the Sea Surface Microlayer and their Effect on Remote Sensing Technology

    NASA Astrophysics Data System (ADS)

    Kurata, N.; Vella, K.; Tartar, A.; Matt, S.; Shivji, M.; Perrie, W. A.; Soloviev, A.

    2012-12-01

    Synthetic aperture radar remote sensing captures various fine-scale features on the ocean surface such as coastal discharges, oil pollution, vessel traffic, algal blooms and sea slicks. Although numerous factors potentially affect the synthetic aperture radar imaging process, the influence of biogenic and anthropogenic surfactants has been suggested as one of the primary parameters, especially under relatively low wind conditions. Surfactants have a tendency to dampen the short gravity-capillary ocean waves causing the sea surface to smoothen, thus allowing the radar to detect areas of surfactants. Surfactants are found in sea slicks, which are the accumulation of organic material shaped as elongated bands on the ocean's surface. Sea slicks are often observable with the naked eye due to their glassy appearance and can also be seen on synthetic aperture radar images as dark scars. While the sources of surfactants can vary, some are known to be of marine bacteria origin. Countless numbers of marine bacteria are present in the oceanic environment, and their biogeochemical contributions cannot be overlooked. Not only does marine-bacteria produce surfactants, but they also play an important role in the transformation of surfactants. In this study, we profiled the surfactant-associated bacteria composition within the biogenic thin layer of the ocean surface more commonly referred as the sea surface microlayer. Bacterial samples were collected from the sea surface microlayer for comparative analysis from both within and outside of sea slick areas as well as the underlying subsurface water. The bacterial microlayer sampling coincided with synthetic aperture radar satellite, RADARSAT-2, overpasses to demonstrate the simultaneous in-situ measurements during a satellite image capture. The sea surface microlayer sampling method was designed to enable aseptic bacterial sampling. A 47 mm polycarbonate membrane was utilized at each sampling site to obtain a snapshot of the

  6. Surface and sub-surface multi-proxy reconstruction of middle to late Holocene palaeoceanographic changes in Disko Bugt, West Greenland

    NASA Astrophysics Data System (ADS)

    Moros, Matthias; Lloyd, Jeremy M.; Perner, Kerstin; Krawczyk, Diana; Blanz, Thomas; de Vernal, Anne; Ouellet-Bernier, Marie-Michele; Kuijpers, Antoon; Jennings, Anne E.; Witkowski, Andrzej; Schneider, Ralph; Jansen, Eystein

    2016-01-01

    We present new surface water proxy records of meltwater production (alkenone derived), relative sea surface temperature (diatom, alkenones) and sea ice (diatoms) changes from the Disko Bugt area off central West Greenland. We combine these new surface water reconstructions with published proxy records (benthic foraminifera - bottom water proxy; dinocyst assemblages - surface water proxy), along with atmospheric temperature from Greenland ice core and Greenland lake records. This multi-proxy approach allows us to reconstruct centennial scale middle to late Holocene palaeoenvironmental evolution of Disko Bugt and the Western Greenland coastal region with more detail than previously available. Combining surface and bottom water proxies identifies the coupling between ocean circulation (West Greenland Current conditions), the atmosphere and the Greenland Ice Sheet. Centennial to millennial scale changes in the wider North Atlantic region were accompanied by variations in the West Greenland Current (WGC). During periods of relatively warm WGC, increased surface air temperature over western Greenland led to ice sheet retreat and significant meltwater flux. In contrast, during periods of cold WGC, atmospheric cooling resulted in glacier advances. We also identify potential linkages between the palaeoceanography of the Disko Bugt region and key changes in the history of human occupation. Cooler oceanographic conditions at 3.5 ka BP support the view that the Saqqaq culture left Disko Bugt due to deteriorating climatic conditions. The cause of the disappearance of the Dorset culture is unclear, but the new data presented here indicate that it may be linked to a significant increase in meltwater flux, which caused cold and unstable coastal conditions at ca. 2 ka BP. The subsequent settlement of the Norse occurred at the same time as climatic amelioration during the Medieval Climate Anomaly and their disappearance may be related to harsher conditions at the beginning of the

  7. Study of electromagnetic composite scattering from a ship-generated internal wave wake and its underlying sea surface

    NASA Astrophysics Data System (ADS)

    Li, Ning; Zhang, Min; Nie, Ding; Sun, Rong-Qing

    2015-10-01

    This paper presents a numerical investigation of electromagnetic scattering from ship-generated internal wave wake and its underlying two-dimensional sea surfaces. The geometric modeling of internal wave wake and linear sea surfaces as well as nonlinear choppy wave model (CWM) sea surfaces are performed successively. Then, the normalized radar cross-section (NRCS) calculations are carried out using second-order small-slope approximation (SSA-2) in bistatic and monostatic configurations. To study the scattering characteristics of internal wave wakes that usually have a large coverage area, the calculations are performed in four successive regions. The results reflect that the scattering signals of four regions are distinguished from those of sea surface without wake; furthermore, the NRCSs for CWM sea surfaces with internal wave wakes are both larger than those of the linear sea surfaces with internal wave wakes in bistatic and monostatic configurations.

  8. Reconstructing past sea surface temperatures: Correcting for diagenesis of bulk marine carbonate

    SciTech Connect

    Schrag, D.P.; DePaolo, D.J. |; Richter, F.M.

    1995-06-01

    A numerical model which describes oxygen isotope exchange during burial and recrystallization of deep-sea carbonate is used to obtain information on how sea surface temperatures have varied in the past by correcting measured {delta}{sup 18}O values of bulk carbonate for diagenetic overprinting. Comparison of bulk carbonate and planktonic foraminiferal {delta}{sup 18}O records from ODP site 677A indicates that the oxygen isotopic composition of bulk carbonate does reflect changes in sea surface temperature and {delta}{sup 18}O. At ODP Site 690, we calculate that diagenetic effects are small, and that both bulk carbonate and planktonic foraminiferal {delta}{sup 18}O records accurately reflect Paleogene warming of high latitude surface oceans, biased from diagenesis by no more than 1{degrees}C. The same is likely to be true for other high latitude sites where sedimentation rates are low. At DSDP sites 516 and 525, the effects of diagenesis are more significant. Measured {delta}{sup 18}O values of Eocene bulk carbonates are more than 2% lower at deeply buried site 516 than at site 525, consistent with the model prediction that the effects of diagenesis should be proportional to sedimentation rate. Model-corrections reconcile the differences in the data between the two sites; the resulting paleotemperature reconstruction indicates a 4{degrees}C cooling of mid-latitude surface oceans since the Eocene. We show that the data are consistent with constant equatorial sea surface temperatures through most of the Cenozoic, with the possible exception of the early Eocene, when slightly higher temperatures are indicated. We suggest that the lower equatorial sea surface temperatures for the Eocene and Oligocene reported in other oxygen isotope studies are artifacts of diagenetic recrystallization, and that it is impossible to reconstruct accurately equatorial sea surface temperatures without explicitly accounting for diagenetic overprinting.

  9. Changing surface water conditions for the last 500 ka in the Southeast Atlantic:Tracking Agulhas leakage using UK37' and δD

    NASA Astrophysics Data System (ADS)

    Petrick, Benjamin; McClymont, Erin; van der Meer, Marcel; Marret, Fabienne

    2015-04-01

    The Southeast Atlantic Ocean is an important component of global ocean circulation, as it includes heat and salt transfer into the Atlantic through Agulhas Leakage. Here, we reconstruct sea surface temperatures (SSTs) and sea surface salinity from Ocean Drilling Program (ODP) Site 1087 in the Southeast Atlantic to investigate surface ocean circulation patterns during the late Pleistocene (0-500 ka). The alkenone-derived U37K'index and assemblages of dinoflagellate cysts are used to reconstruct SSTs. The hydrogen isotope composition of the alkenones (δDalkenone) is used to reconstruct changes in sea-surface salinity. The greatest amplitude of SST warming precedes decreases in benthic δ18O and therefore occurs early in the transition from glacials to interglacials. The timing of the early warming is consistent with previously published foraminifera reconstructions from the same site (Caley et al., 2012). However, δDalkenone decreases at the start of interglacials, suggesting that sea surface salinity increased earlier than the deglacial warmings, and indicating that the pattern of Agulhas leakage is more complex than suggested by SST proxies alone. Furthermore, the δDalkenonevalues indicate a strong salinity increases occurred before both MIS 11 and MIS 1, which are both periods where there is evidence of connection between increased Agulhas Leakage and a stronger Atlantic meridional overturning circulation (AMOC). Finally, the ODP site 1087 record shows an overall trend of increasing SSTs and δDalkenone towards the present day, suggesting that Agulhas leakage has strengthened since 500 ka, which may have impacted the intensity of the AMOC. Caley, T., Giraudeau, J., Malaize, B., Rossignol, L., Pierre, C., 2012. Agulhas leakage as a key process in the modes of Quaternary climate changes. Proc. Natl. Acad. Sci. 109, 6835-6839. doi:10.1073/pnas.1115545109

  10. Parabolic equation modeling of high frequency acoustic transmission with an evolving sea surface.

    PubMed

    Senne, J; Song, A; Badiey, M; Smith, K B

    2012-09-01

    The present paper examines the temporal evolution of acoustic fields by modeling forward propagation subject to sea surface dynamics with time scales of less than a second to tens of seconds. A time-evolving rough sea surface model is combined with a rough surface formulation of a parabolic equation model for predicting time-varying acoustic fields. Surface waves are generated from surface wave spectra, and stepped in time using a Runge-Kutta integration technique applied to linear evolution equations. This evolving, range-dependent surface information is combined with other environmental parameters and input to the acoustic model, giving an approximation of the time-varying acoustic field. The wide-angle parabolic equation model manages the rough sea surfaces by molding them into the boundary conditions for calculations of the near-surface acoustic field. This merged acoustic model is validated using concurrently-collected acoustic and environmental information, including surface wave spectra. Data to model comparisons demonstrate that the model is able to approximate the ensemble-averaged acoustic intensity at ranges of about a kilometer for acoustic signals of around 15 kHz. Furthermore, the model is shown to capture variations due to surface fluctuations occurring over time scales of less than a second to tens of seconds.

  11. Sea ice and surface water circulation, Alaskan Continental Shelf

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    The author has identified the following significant results. The boundaries of land-fast ice, distribution of pack ice, and major polynya were studied in the vicinity of the Bering Strait. Movement of pack ice during 24 hours was determined by plotting the distinctly identifiable ice floes on ERTS-1 imagery obtained from two consecutive passes. Considerably large shallow area along the western Seward Peninsula just north of the Bering Strait is covered by land fast ice. This ice hinders the movement of ice formed in eastern Chukchi Sea southward through the Bering Strait. The movement of ice along the Russian coast is relatively faster. Plotting of some of the ice floes indicated movement of ice in excess of 30 km in and south of the Bering Strait between 6 and 7 March, 1973. North of the Bering Strait the movement approached 18 km. The movement of ice observed during March 6 and 7 considerably altered the distribution and extent of polynya. These features when continually plotted should be of considerable aid in navigation of ice breakers. The movement of ice will also help delineate the migration and distribution of sea mammals.

  12. A GIS Approach to Wind,SST(Sea Surface Temperature) and CHL(Chlorophyll) variations in the Caspian Sea

    NASA Astrophysics Data System (ADS)

    Mirkhalili, Seyedhamzeh

    2016-07-01

    Chlorophyll is an extremely important bio-molecule, critical in photosynthesis, which allows plants to absorb energy from light. At the base of the ocean food web are single-celled algae and other plant-like organisms known as Phytoplankton. Like plants on land, Phytoplankton use chlorophyll and other light-harvesting pigments to carry out photosynthesis. Where Phytoplankton grow depends on available sunlight, temperature, and nutrient levels. In this research a GIS Approach using ARCGIS software and QuikSCAT satellite data was applied to visualize WIND,SST(Sea Surface Temperature) and CHL(Chlorophyll) variations in the Caspian Sea.Results indicate that increase in chlorophyll concentration in coastal areas is primarily driven by terrestrial nutrients and does not imply that warmer SST will lead to an increase in chlorophyll concentration and consequently Phytoplankton abundance.

  13. Sea-surface temperature and salinity mapping from remote microwave radiometric measurements of brightness temperature

    NASA Technical Reports Server (NTRS)

    Hans-Juergen, C. B.; Kendall, B. M.; Fedors, J. C.

    1977-01-01

    A technique to measure remotely sea surface temperature and salinity was demonstrated with a dual frequency microwave radiometer system. Accuracies in temperature of 1 C and in salinity of part thousand for salinity greater than 5 parts per thousand were attained after correcting for the influence of extraterrestrial background radiation, atmospheric radiation and attenuation, sea-surface roughness, and antenna beamwidth. The radiometers, operating at 1.43 and 2.65 GHz, comprise a third-generation system using null balancing and feedback noise injection. Flight measurements from an aircraft at an altitude of 1.4 km over the lower Chesapeake Bay and coastal areas of the Atlantic Ocean resulted in contour maps of sea-surface temperature and salinity with a spatial resolution of 0.5 km.

  14. The In-situ Validation of ATSR-2 and AATSR sea surface temperatures

    NASA Astrophysics Data System (ADS)

    Nightingale, T.

    Three Along Track Scanning Radiometers have now been launched on the European Space Agency's ERS-1, ERS-2 and, most recently, Envisat remote sensing platforms. These radiometers are distinguished by their dual views to the sea surface and the care taken with their on-board calibration systems. The primary product is a "skin" sea surface temperature, calculated with coefficients derived from a physically-based model of radiative transfer. The high estimated accuracy of the SST products (0.3K) and the explicit production of skin, rather than the more familiar pseudo-bulk SSTs, constrain the methods by which the product can be validated. In-situ validation measurements of skin SST made with the Scanning Infrared Sea surface Temperature Radiometer (SISTeR), are described and compared with ATSR-2 and the Advanced ATSR (AATSR) products for a range of waters.

  15. [Distributional characteristics of nutrients in the sea-surface microlayer and subsurface water of the Bohai and Yellow Sea in summer].

    PubMed

    Wang, Wen-Tao; Yang, Gui-Peng; Yu, Juan; Wu, Guan-Wei

    2013-08-01

    The horizontal distributional characteristics of nutrients (DIN, PO4(3-) -P, SiO3(2-) -Si) were studied in the sea-surface microlayer (SML) and subsurface water of the Bohai and Yellow Sea in June 2011, and the vertical distributions of nutrients in the transects of the Yellow Sea Cold Water Mass and the north of the Changjiang River estuary were also investigated. The results showed that the nutrient concentrations in the sea-surface microlayer and subsurface water decreased gradually from inshore to offshore, and higher values were observed in the Changjiang River estuary. A tongue-shaped distribution was observed in the south of the Yellow Sea as a result of the Changjiang diluted water. Stratification occurred in the surface layer and vertical mixing characteristics were observed in the bottom due to the influence of the Yellow Sea Cold Water Mass. In the vertical distributions, higher concentrations of DIN and SiO3(2-) -Si in the north of the Changjiang River estuary occurred in the sea surface compared with the bottom due to the Changjiang River diluted water. The enrichment results of NH(+) -N, NO2(-) -N, NO3(-)-N, PO4(3-) -P, SiO3(2-)-Si and DIN showed that the sea-surface microlayer displayed an apparent enrichment for nutrients except NO3(-) -N, and the mean enrichment factors ranged from 1.37 to 2.21.

  16. The impact of sea surface currents in wave power potential modeling

    NASA Astrophysics Data System (ADS)

    Zodiatis, George; Galanis, George; Kallos, George; Nikolaidis, Andreas; Kalogeri, Christina; Liakatas, Aristotelis; Stylianou, Stavros

    2015-11-01

    The impact of sea surface currents to the estimation and modeling of wave energy potential over an area of increased economic interest, the Eastern Mediterranean Sea, is investigated in this work. High-resolution atmospheric, wave, and circulation models, the latter downscaled from the regional Mediterranean Forecasting System (MFS) of the Copernicus marine service (former MyOcean regional MFS system), are utilized towards this goal. The modeled data are analyzed by means of a variety of statistical tools measuring the potential changes not only in the main wave characteristics, but also in the general distribution of the wave energy and the wave parameters that mainly affect it, when using sea surface currents as a forcing to the wave models. The obtained results prove that the impact of the sea surface currents is quite significant in wave energy-related modeling, as well as temporally and spatially dependent. These facts are revealing the necessity of the utilization of the sea surface currents characteristics in renewable energy studies in conjunction with their meteo-ocean forecasting counterparts.

  17. Simulated wind power off-shore using different parametrizations for the sea surface roughness

    NASA Astrophysics Data System (ADS)

    Frank, Helmut P.; Larsen, Søren E.; Højstrup, Jørgen

    2000-04-01

    The equation for the dependence of the Charnock constant on wave age proposed by Johnson et al. (Journal of Physical Oceanography 1998; 28: 1702 - 1716) is extended to include conditions of very young waves or short fetches. The effect on the simulated average wind speed and average wind power density off a straight east coast in Denmark is investigated by numerical simulations. Calculations are also performed employing the classical Charnock relation and a constant roughness of the sea. The formulations with variable sea surface roughness are combined with the equation for a smooth water surface for low winds. The wind climate is calculated with the Karlsruhe Atmospheric Mesoscale Model (KAMM) in 84 classes of the geostrophic wind. The difference between the fetch-dependent and the fetch-independent formulation is very small. Even a constant sea surface roughness yields good results near the coast. The influence of stratification, i.e. temperature differences between sea and land, is much more important than the fetch dependence of the sea surface roughness.

  18. Sea surface retracking and classification of CryoSat-2 altimetry observations in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Stenseng, L.; Piccioni, G.; Andersen, O. B.; Knudsen, P.

    2015-12-01

    In this study we present the retracking and classification methods for CryoSat-2 SAR waveforms, developed for the determination of sea surface heights in the Arctic Ocean. The obtained sea surface heights (SSH) are used to decrease the gap in satellite observations from 82 degrees North to 88 degrees North in the DTU15 mean sea surface (MSS) and mean dynamic topography (MDT).Radar altimetry satellites has observed the sea surface for more than 25 years and thereby obtain data to determine accurate MSSs and estimate sea level trends related to climate changes. In combination with the improvements of global geoids it has furthermore provided an opportunity to improve the MDT related to ocean currents.After the launch of CryoSat-2 in 2010 the coverage was increased dramatically while the introduction of the synthetic aperture radar (SAR) and SAR interferometry (SARin) mode increased the amount of useful echoes in the Arctic Ocean. The new types of radar observation modes have been investigated and methods to retrack and classify the waveforms have been implemented in LARS the advanced retracking system (LARS). Finally the SSH observations obtained from CryoSat-2 with LARS is merged with previous satellite radar altimetry data to derive the DTU15 MSS.

  19. Phytoplankton assemblages and lipid biomarkers indicate sea-surface warming and sea-ice decline in the Ross Sea during Marine Isotope sub-Stage 5e

    NASA Astrophysics Data System (ADS)

    Hartman, Julian D.; Sangiorgi, Francesca; Peterse, Francien; Barcena, Maria A.; Albertazzi, Sonia; Asioli, Alessandra; Giglio, Federico; Langone, Leonardo; Tateo, Fabio; Trincardi, Fabio

    2016-04-01

    The Marine Isotope sub-Stage 5e (~ 125 - 119 kyrs BP), the last interglacial period before the present, is believed to have been globally warmer (~ 2°C) than today. Studying this time interval might therefore provide insights into near future climate state given the ongoing climate change and global temperature increase. Of particular interest are the expected changes in polar ice cover. One important aspect of the cryosphere is sea-ice, which influences albedo, deep and surface water currents, and phytoplankton production, and thus affects the global climate system. To investigate whether changes in sea-ice cover occurred in the Southern Ocean close to Antarctica during Marine Isotope sub-Stage 5e dinoflagellate and diatom assemblages have been analyzed in core AS05-10, drilled in the continental slope off the Drygalski basin (Ross Sea) at a water depth of 2377 m. The core was drilled within the frame of the PNRA 2009/A2.01 project, an Italian project with a multidisciplinary approach, and covers the interval from Present to Marine Isotope Stage (MIS) 7. The core stratigraphy is based on diatom bioevents and on the climate cyclicity provided by the variations of the diatom assemblages. For this study we focused on the interval from MIS7 to MIS5. A strong reduction of sea-ice-loving diatom taxa with respect to open water-loving diatom taxa is observed during MIS5. In general the production of phytoplankton increases at the base of MIS5 and then slowly decreases. Dinoflagellate cysts, particularly heterotrophic species, are abundant during MIS5e only. The sea surface temperature reconstruction based on the TEX86L, a proxy based on lipid biomarkers produced by Thaumarcheota, shows a 4°C temperature increase from MIS6 to MIS5e. A slightly smaller temperature increase is observed at the onset of MIS7, but this stage is barren of heterotrophic dinoflagellates. All proxies together seem to indicate that the retreat of the summer sea-ice in the Ross Sea during MIS5e was

  20. Analyzing the Effects of Climate Change on Sea Surface Temperature in Monitoring Coral Reef Health in the Florida Keys Using Sea Surface Temperature Data

    NASA Technical Reports Server (NTRS)

    Jones, Jason; Burbank, Renane; Billiot, Amanda; Schultz, Logan

    2011-01-01

    This presentation discusses use of 4 kilometer satellite-based sea surface temperature (SST) data to monitor and assess coral reef areas of the Florida Keys. There are growing concerns about the impacts of climate change on coral reef systems throughout the world. Satellite remote sensing technology is being used for monitoring coral reef areas with the goal of understanding the climatic and oceanic changes that can lead to coral bleaching events. Elevated SST is a well-documented cause of coral bleaching events. Some coral monitoring studies have used 50 km data from the Advanced Very High Resolution Radiometer (AVHRR) to study the relationships of sea surface temperature anomalies to bleaching events. In partnership with NOAA's Office of National Marine Sanctuaries and the University of South Florida's Institute for Marine Remote Sensing, this project utilized higher resolution SST data from the Terra's Moderate Resolution Imaging Spectroradiometer (MODIS) and AVHRR. SST data for 2000-2010 was employed to compute sea surface temperature anomalies within the study area. The 4 km SST anomaly products enabled visualization of SST levels for known coral bleaching events from 2000-2010.

  1. Towards GPS Surface Reflection Remote Sensing of Sea Ice Conditions

    NASA Technical Reports Server (NTRS)

    Komjathy, A.; Maslanik, J. A.; Zavorotny, V. U.; Axelrad, P.; Katzberg, S. J.

    2000-01-01

    This paper describes the research to extend the application of Global Positioning System (GPS) signal reflections, received by airborne instruments, to cryospheric remote sensing. The characteristics of the GPS signals and equipment afford the possibility of new measurements not possible with existing radar and passive microwave systems. In particular, the GPS receiving systems are small and light-weight, and as such are particularly well suited to be deployed on small aircraft or satellite platforms with minimal impact. Our preliminary models and experimental results indicate that reflected GPS signals have potential to provide information on the presence and condition of sea and fresh-water ice as well as the freeze/thaw state of frozen ground. In this paper we show results from aircraft experiments over the ice pack near Barrow, Alaska suggesting correlation between forward scattered GPS returns and RADARSAT backscattered signals.

  2. Annual variations in sea surface wind speed around Japan observed by ASCAT

    NASA Astrophysics Data System (ADS)

    Takeyama, Y.; Shimada, S.; Ohsawa, T.; Kozai, K.; Kogaki, T.

    2015-12-01

    Sea surface wind speeds and these statistics can be applied for many marine industrial activities. For example, the averaged wind speed is crucial information for a site selection of an offshore wind farm. It has widely been recognized that a total amount of the offshore wind generation is strongly depended on the annual average wind speeds. A advanced scatterometer (ASCAT), which is a kind of scatterometer aboard METOP-A and B, has observed sea surface wind speeds at the height of 10 m above the sea surface approximately twice a day using active microwaves. The annual average wind speed can be calculated from the observed wind speed. For an actual use of the annual average wind speed, generalities and representativeness of the wind speed must be clarified. To investigate annual variations in sea surface wind speed around Japan (120°E to 165°E, 19°N to 49°N), the annual average wind speeds and these standard deviations are calculated from 5 years of ASCAT observations from 2010 through 2014. It is found that there are some sea areas where standard deviations are relatively higher than their surroundings. Annual average wind speed maps indicate that the high standard deviation is caused by strong winds from Eurasia in the winter of 2011 in part of North Pacific Ocean and Sea of Okhotsk. Additionally standard deviations for only winter are also higher than for summer in those sea areas. Therefore the strong wind speed in the winter of a particular year can easily affect to the annual average wind speed. Meanwhile off the coast of Niigata and Hokkaido, there are also higher standard deviation areas than their surroundings. Differences between monthly maximum wind speeds for the winter and minimum wind speeds for the summer in these areas are larger and the large differences seem to be a cause of the high standard deviations.

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

    NASA Astrophysics Data System (ADS)

    Katlein, C.; Arndt, S.; Nicolaus, M.; Perovich, D. K.; Jakuba, M.; Suman, S.; Elliott, S.; Whitcomb, L. L.; McFarland, C.; Gerdes, R.; Boetius, A.

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  5. The influence of sea ice extent variability on the Greenland surface mass and energy balance

    NASA Astrophysics Data System (ADS)

    Tedesco, M.; Quillet, A.; Alexander, P. M.; Rennermalm, A. K.; Stroeve, J. C.; Fettweis, X.; Orantes, E. J.; Tuia, D.; Parkan, M.

    2012-12-01

    Sea ice variations are known to affect local surface air temperature regimes, but other influences, in particular atmospheric circulation, are important. Several recent studies have found that, via atmospheric transport, atmospheric warming driven by sea ice loss affects surrounding areas. Indeed, while observed amplified autumn warming is focused over the areas where the sea ice has disappeared in summers (e.g. Beaufort, Chukchi and E. Siberian seas), wind patterns spread the anomalous warmth over open water areas to adjacent land areas and may extend up to 1500 km inland during periods of rapid ice loss through the 21st century. It is plausible that changes in the sea-ice/open- water regime surrounding the ice sheet are capable of modulating Greenland surface melt and precipitation. Diminished sea ice around Greenland may lead to large fluxes of heat into the atmosphere that could lead to enhanced ice-sheet surface-melt, increased coastal water temperatures, alter the vertical stability of the atmosphere, moisture availability and regional baroclinicity. Here we report results concerning the combined analysis of sea ice extent estimated from spaceborne microwave observations, the outputs of a regional climate model (Modèle Atmosphérique Régional, MAR) and in-situ measured quantities. In particular, we study the impact of the open water along the coasts of Greenland (divided into 16 longitudinal zones and two latitudinal ones) on surface mass balance (e.g., meltwater production, runoff, precipitation) and surface energy quantities (e.g., albedo, sensible heat flux, etc.) simulated over the Greenland ice sheet for the period 1979 - 2011. Among other things, our results indicate a statistically significant correlation between open water spatio-temporal variability and integrated liquid water content, with correlation values being highest for the month of August along the Southwest region of Greenland (e.g., Kangerlussuaq). Such dependency persists even after the

  6. Temporal variability of remotely sensed suspended sediment and sea surface temperature patterns in Mobile Bay, Alabama

    USGS Publications Warehouse

    Rucker, J.B.; Stumpf, R.P.; Schroeder, W.W.

    1990-01-01

    Distribution patterns of suspended sediments and sea surface temperatures in, Mobile Bay were derived from algorithms using digital data from the visible, near infrared, and infrared channels of the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-TIROS-N satellite. Closely spaced AVHRR scenes for January 20, 24, and 29, 1982, were compared with available environmental information taken during the same period. A complex interaction between river discharge, winds, and astronomical tides controlled the distribution patterns of suspended sediments. These same variables, coupled with air temperatures, also governed the distribution patterns of sea surface temperatures. ?? 1990 Estuarine Research Federation.

  7. Production of global sea surface temperature fields for the Jet Propulsion Laboratory workshop comparisons

    NASA Technical Reports Server (NTRS)

    Hilland, J. E.; Njoku, E. G.; Chelton, D. B.

    1985-01-01

    Sea surface temperature (SST) is measured from space by the advanced very high resolution radiometer (AVHRR), scanning multichannel microwave radiometer (SMMR), high resolution infrared sounder (HIRS) and VISSR atmospheric sounder (VAS). Typical accuracies have been reported from 0.5 C regionally to 2.0 C on a global basis. To evaluate the accuracy of the satellite-derived sea surface temperatures, a series of three workshops was organized to provide uniform data reduction and analysis. The analytical techniques used to intercompare satellite and in situ measurements are described in detail. Selected results showed the overall average rms errors were in the range 0.5-1.0 C.

  8. Flux measurements in the surface Marine Atmospheric Boundary Layer over the Aegean Sea, Greece.

    PubMed

    Kostopoulos, V E; Helmis, C G

    2014-10-01

    Micro-meteorological measurements within the surface Marine Atmospheric Boundary Layer took place at the shoreline of two islands at northern and south-eastern Aegean Sea of Greece. The primary goal of these experimental campaigns was to study the momentum, heat and humidity fluxes over this part of the north-eastern Mediterranean Sea, characterized by limited spatial and temporal scales which could affect these exchanges at the air-sea interface. The great majority of the obtained records from both sites gave higher values up to factor of two, compared with the estimations from the most widely used parametric formulas that came mostly from measurements over open seas and oceans. Friction velocity values from both campaigns varied within the same range and presented strong correlation with the wind speed at 10 m height while the calculated drag coefficient values at the same height for both sites were found to be constant in relation with the wind speed. Using eddy correlation analysis, the heat flux values were calculated (virtual heat fluxes varied from -60 to 40 W/m(2)) and it was found that they are affected by the limited spatial and temporal scales of the responding air-sea interaction mechanism. Similarly, the humidity fluxes appeared to be strongly influenced by the observed intense spatial heterogeneity of the sea surface temperature.

  9. The Last Interglacial Labrador Sea: A Pervasive Millennial Oscillation In Surface Water Conditions Without Labrador Sea Water Formation

    NASA Astrophysics Data System (ADS)

    Hillaire-Marcel, C.; de Vernal, A.

    A multi-proxy approach was developed to document secular to millenial changes of potential density in surface, mesopelagic, and bottom waters of the Labrador Sea, thus allowing to reconstruct situations when winter convection with intermediate or deep water formation occurred in the basin. This approach relies on dinocyst-transfer functions providing estimates of sea-surface temperature and salinity that are used to calibrate past-relationships between oxygen 18 contents in calcite and potential density gradients. The oxygen isotope compositions of epipelagic (Globigerina bul- loides), deeper-dwelling (Neogloboquadrina pachyderma, left coiling), and benthic (Uvigerina peregrina and Cibicides wuellerstorfi) foraminifera, then allow to extrap- olate density gradients between the corresponding water layers. This approach has been tested in surface sediments in reference to modern hydrographic conditions at several sites from the NW North Atlantic, then used to reconstruct past conditions from high resolution studies of cores raised from the southern Greenland Rise (off Cape Farewell). Results indicate that the modern-like regime established during the early Holocene and full developed after 7 ka only. It is marked by weak density gradi- ents between the surface and intermediate water masses, allowing winter convection down to a lower pycnocline between intermediate and deep-water masses, thus the formation of intermediate Labrador Sea Water (LSW). Contrasting with the middle to late Holocene situation, since the last interglacial and throughout the last climatic cycle, a single and dense water mass seems to have occupied the water column below a generally low-density surface water layer, thus preventing deep convection. There- fore, the production of LSW seems to be feature specific to the present interglacial interval that could soon cease to exist, due to global warming, as suggested by recent ocean model experiments and by the fact that it never occurred during the

  10. Co-incident 3D mapping of sea ice surface elevation and ice draft in the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Doble, M. J.; Forsberg, R.; Haas, C.; Hanson, S.; Hendriks, S.; Martin, T.; Skourup, H.; Wadhams, P.

    2007-12-01

    Co-incident measurements of sea ice freeboard, thickness and draft were made during the Applied Physics Laboratory Ice Station (APLIS), in April 2007. The campaign was the first time that full three-dimensional mapping of sea ice freeboard and sea ice draft have been achieved simultaneously. Freeboard was measured across a swath width of 300 m at 1 m spatial resolution, using a laser profilometer flown aboard a Twin Otter aircraft. Ice draft was measured across a swath width of approximately 80 m at 0.5 m spatial resolution, using a Gavia AUV fitted with a GeoAcoustics phase-measuring swath sonar. Ice thickness was also measured along co-incident tracks using a helicopter-borne electromagnetic sounding instrument (HEM bird). The laser profilometer and AUV-mounted sonar rely on the assumption of isostatic balance when deriving ice thickness estimates from the ice surface and underside profiles, while the HEM bird records both surfaces simultaneously and independently, though averaging over a significant footprint (30 m) for the underside of the ice. Though the extent of the APLIS dataset was limited by the radius of AUV operations, the dataset will significantly improve our understanding of ice volume in deformed ice areas, particularly our understanding of the contribution of ridges and rubble fields to total Arctic ice volume, their isostatic balance and questions of block-scale porosity. The data will serve to better constrain the effects of porosity and footprint on the operational HEM measurements and, conversely, the HEM measurements will allow conclusions about the impact of the isostatic balance assumption on ice thickness estimates derived from mapping of one surface.

  11. Enrichment of Fusobacteria in Sea Surface Oil Slicks from the Deepwater Horizon Oil Spill.

    PubMed

    Gutierrez, Tony; Berry, David; Teske, Andreas; Aitken, Michael D

    2016-01-01

    The Deepwater Horizon (DWH) oil spill led to rapid microbial community shifts in the Gulf of Mexico, including the formation of unprecedented quantities of marine oil snow (MOS) and of a massive subsurface oil plume. The major taxa that bloomed in sea surface oil slicks during the spill included Cycloclasticus, and to a lesser extent Halomonas, Alteromonas, and Pseudoalteromonas-organisms that grow and degrade oil hydrocarbons aerobically. Here, we show that sea surface oil slicks at DWH contained obligate and facultative anaerobic taxa, including members of the obligate anaerobic phylum Fusobacteria that are commonly found in marine sediment environments. Pyrosequencing analysis revealed that Fusobacteria were strongly selected for when sea surface oil slicks were allowed to develop anaerobically. These organisms have been found in oil-contaminated sediments in the Gulf of Mexico, in deep marine oil reservoirs, and other oil-contaminated sites, suggesting they have putative hydrocarbon-degrading qualities. The occurrence and strong selection for Fusobacteria in a lab-based incubation of a sea surface oil slick sample collected during the spill suggests that these organisms may have become enriched in anaerobic zones of suspended particulates, such as MOS. Whilst the formation and rapid sinking of MOS is recognised as an important mechanism by which a proportion of the Macondo oil had been transported to the sea floor, its role in potentially transporting microorganisms, including oil-degraders, from the upper reaches of the water column to the seafloor should be considered. The presence of Fusobacteria on the sea surface-a highly oxygenated environment-is intriguing, and may be explained by the vertical upsurge of oil that provided a carrier to transport these organisms from anaerobic/micro-aerophilic zones in the oil plume or seabed to the upper reaches of the water column. We also propose that the formation of rapidly-sinking MOS may have re-transported these

  12. Enrichment of Fusobacteria in Sea Surface Oil Slicks from the Deepwater Horizon Oil Spill.

    PubMed

    Gutierrez, Tony; Berry, David; Teske, Andreas; Aitken, Michael D

    2016-07-27

    The Deepwater Horizon (DWH) oil spill led to rapid microbial community shifts in the Gulf of Mexico, including the formation of unprecedented quantities of marine oil snow (MOS) and of a massive subsurface oil plume. The major taxa that bloomed in sea surface oil slicks during the spill included Cycloclasticus, and to a lesser extent Halomonas, Alteromonas, and Pseudoalteromonas-organisms that grow and degrade oil hydrocarbons aerobically. Here, we show that sea surface oil slicks at DWH contained obligate and facultative anaerobic taxa, including members of the obligate anaerobic phylum Fusobacteria that are commonly found in marine sediment environments. Pyrosequencing analysis revealed that Fusobacteria were strongly selected for when sea surface oil slicks were allowed to develop anaerobically. These organisms have been found in oil-contaminated sediments in the Gulf of Mexico, in deep marine oil reservoirs, and other oil-contaminated sites, suggesting they have putative hydrocarbon-degrading qualities. The occurrence and strong selection for Fusobacteria in a lab-based incubation of a sea surface oil slick sample collected during the spill suggests that these organisms may have become enriched in anaerobic zones of suspended particulates, such as MOS. Whilst the formation and rapid sinking of MOS is recognised as an important mechanism by which a proportion of the Macondo oil had been transported to the sea floor, its role in potentially transporting microorganisms, including oil-degraders, from the upper reaches of the water column to the seafloor should be considered. The presence of Fusobacteria on the sea surface-a highly oxygenated environment-is intriguing, and may be explained by the vertical upsurge of oil that provided a carrier to transport these organisms from anaerobic/micro-aerophilic zones in the oil plume or seabed to the upper reaches of the water column. We also propose that the formation of rapidly-sinking MOS may have re-transported these

  13. Aquarius and Remote Sensing of Sea Surface Salinity from Space

    NASA Technical Reports Server (NTRS)

    LeVine, David M.; Lagerloef, G. S. E.; Torrusio, S.

    2012-01-01

    Aquarius is an L-band radiometer and scatterometer instrument combination designed to map the salinity field at the surface of the ocean from space. The instrument is designed to provide global salinity maps on a monthly basis with a spatial resolution of 150 km and an accuracy of 0.2 psu. The science objective is to monitor the seasonal and interannual variation of the large scale features of the surface salinity field in the open ocean. This data will promote understanding of ocean circulation and its role in the global water cycle and climate.

  14. Resolving the diurnal cycle in satellite derived sea surface temperatures and its significance on surface heat fluxes

    NASA Astrophysics Data System (ADS)

    Weihs, R. R.; Bourassa, M. A.

    2010-12-01

    Marine surface heat fluxes across the globe need to be resolved on a smaller time scale in order to determine how changes in their diurnal cycle contribute to surface turbulent fluxes. In order to do this, the sea surface temperatures used to calculate the fluxes also need to accurately represent diurnal changes. Since most satellite derived sea surface temperature products are time-averaged and smoothed so that intradiurnal variations are neglected, and insitu measurements are scarce in global spatial coverage, modeling of the diurnal cycle of SSTs becomes necessary. A bulk flux model, POSH (Gentemann et al. 2009), will be used to calculate a global field of diurnally varying sea surface temperatures (dSSTs) over the course of 2 months in two different annual seasons, winter and summer. As the model produces a dSST field, surface turbulent heat fluxes are calculated using the Bourassa (2006) flux model. In order to compute fluxes, bulk atmospheric variables are taken from the MERRA (Modern Era Retrospective-Analysis for Research and Applications) reanalysis dataset. Sea surface temperatures are obtained from the AVHRR-only Reynolds Daily OI Sea Surface Temperature product (Reynolds et al. 2007). The Reynolds SST is bias-corrected relative to a 7-day in-situ SST so therefore it does not resolve the diurnal cycle itself. The Reynolds SST product will serve as a foundation temperature, or the temperature that is independent from the effects of diurnal heating (Donolan et al. 2007), of which the amplitude of the diurnal heating will be added to. Finally, 2-monthly average differences in dSSTs versus Daily OI SSTs and uncertainties in the biases will be compared. From these statistics, climactic and modeling significance of the inclusion of diurnal heating can be evaluated. We find that latent heat fluxes in the tropics are increased by roughly 10 Wm-2 when the diurnal variability is considered (Fig. 1). This change in flux decreases poleward. The tropical changes are

  15. An European historical reconstruction of sea surface dynamics (waves and storm surge) for coastal impact studies

    NASA Astrophysics Data System (ADS)

    Menendez, Melisa; Perez, Jorge; Cid, Alba; Castanedo, Sonia; Losada, Inigo; Medina, Raul; Mendez, Fernando

    2015-04-01

    Despite their outstanding relevance in coastal processes, a study of the sea surface dynamics due to atmospheric wind and pressure variations are rather limited in comparison with the mean sea level rise. Data of waves and surges along the European region are scarce and in-homogeneous, not only in terms of spatial coverage but also in terms of temporal coverage. This study presents two databases focused on a historical reconstruction of: (i) the wind-generated waves (GOW) and (ii) the meteorological sea level component (GOS). The GOW and GOS datasets cover the whole European coast (North Atlantic, North Sea, Baltic Sea, Mediterranean Sea and Black Sea) at high-spatial resolution from 1979 to present. The meteorological sea level component (storm surge) has been generated by the Regional Ocean Model System (ROMS). To take into account non-linear interactions between tides and surges, both dynamics were simulated jointly. Final results of meteorological component of sea level were obtained by subtracting the astronomical tide from the simulated sea surface. The model was set-up for Europe using an orthogonal grid, with a horizontal resolution ranging between 3.5 to 11 km. A spatial domain of approximately 5 km was used for the Black Sea. Local coastal waves can be the integrated result of the ocean surface over a large region of influence. GOW-Europe is designed from a multigrid approach based on the overlapping of two-way nested domains. The coarser spatial resolution along the European coast of GOW is 15 km. The generation and propagation of the sea surface waves of GOW-Europe are simulated with the model WAVEWATCH III v4.18. Effects of non-linear wave-wave interactions, whitecapping and depth-induced refraction are considered in the propagation model. In order to validate GOW and GOS over Europe with available observations, an exhaustive comparison with in-situ and remote measurements was developed. In-situ buoys and tide-gauges are used to compare hourly time

  16. A study of oceanic surface heat fluxes in the Greenland, Norwegian, and Barents Seas

    NASA Technical Reports Server (NTRS)

    Hakkinen, Sirpa; Cavalieri, Donald J.

    1989-01-01

    This study examines oceanic surface heat fluxes in the Norwegian, Greenland, and Barents seas using the gridded Navy Fleet Numerical Oceanography Central surface analysis and the First GARP Global Experiment (FGGE) IIc cloudiness data bases. Monthly and annual means of net and turbulent heat fluxes are computed for the FGGE year 1979. The FGGE IIb data base consisting of individual observations provides particularly good data coverage in this region for a comparison with the gridded Navy winds and air temperatures. The standard errors of estimate between the Navy and FGGE IIb winds and air temperatures are 3.6 m/s and 2.5 C, respectively. The computations for the latent and sensible heat fluxes are based on bulk formulas with the same constant heat exchange coefficient of 0.0015. The results show extremely strong wintertime heat fluxes in the northern Greenland Sea and especially in the Barents Sea in contrast to previous studies.

  17. The Effect of Sea-Surface Sun Glitter on Microwave Radiometer Measurements

    NASA Technical Reports Server (NTRS)

    Wentz, F. J.

    1981-01-01

    A relatively simple model for the microwave brightness temperature of sea surface Sun glitter is presented. The model is an accurate closeform approximation for the fourfold Sun glitter integral. The model computations indicate that Sun glitter contamination of on orbit radiometer measurements is appreciable over a large swath area. For winds near 20 m/s, Sun glitter affects the retrieval of environmental parameters for Sun angles as large as 20 to 25 deg. The model predicted biases in retrieved wind speed and sea surface temperature due to neglecting Sun glitter are consistent with those experimentally observed in SEASAT SMMR retrievals. A least squares retrieval algorithm that uses a combined sea and Sun model function shows the potential of retrieving accurate environmental parameters in the presence of Sun glitter so long as the Sun angles and wind speed are above 5 deg and 2 m/s, respectively.

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

    PubMed Central

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

    2015-01-01

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

  19. Enrichment of Fusobacteria in Sea Surface Oil Slicks from the Deepwater Horizon Oil Spill

    PubMed Central

    Gutierrez, Tony; Berry, David; Teske, Andreas; Aitken, Michael D.

    2016-01-01

    The Deepwater Horizon (DWH) oil spill led to rapid microbial community shifts in the Gulf of Mexico, including the formation of unprecedented quantities of marine oil snow (MOS) and of a massive subsurface oil plume. The major taxa that bloomed in sea surface oil slicks during the spill included Cycloclasticus, and to a lesser extent Halomonas, Alteromonas, and Pseudoalteromonas—organisms that grow and degrade oil hydrocarbons aerobically. Here, we show that sea surface oil slicks at DWH contained obligate and facultative anaerobic taxa, including members of the obligate anaerobic phylum Fusobacteria that are commonly found in marine sediment environments. Pyrosequencing analysis revealed that Fusobacteria were strongly selected for when sea surface oil slicks were allowed to develop anaerobically. These organisms have been found in oil-contaminated sediments in the Gulf of Mexico, in deep marine oil reservoirs, and other oil-contaminated sites, suggesting they have putative hydrocarbon-degrading qualities. The occurrence and strong selection for Fusobacteria in a lab-based incubation of a sea surface oil slick sample collected during the spill suggests that these organisms may have become enriched in anaerobic zones of suspended particulates, such as MOS. Whilst the formation and rapid sinking of MOS is recognised as an important mechanism by which a proportion of the Macondo oil had been transported to the sea floor, its role in potentially transporting microorganisms, including oil-degraders, from the upper reaches of the water column to the seafloor should be considered. The presence of Fusobacteria on the sea surface—a highly oxygenated environment—is intriguing, and may be explained by the vertical upsurge of oil that provided a carrier to transport these organisms from anaerobic/micro-aerophilic zones in the oil plume or seabed to the upper reaches of the water column. We also propose that the formation of rapidly-sinking MOS may have re

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

    PubMed Central

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

    2015-01-01

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

  1. SeaRISE Greenland: On "spin-up" procedures using InSAR surface velocities

    NASA Astrophysics Data System (ADS)

    Aschwanden, A.; Khroulev, C.

    2009-12-01

    Sea-level Response to Ice Sheet Evolution (SeaRISE) is a community effort to provide quantitative estimates of ice sheet contributions to sea level for the 21st century, along with appropriate uncertainties. As stated in a white paper for SeaRISE, one requirement for this effort is that the model is devoid of non-physical transients in the behavior of the ice sheet at the present day, so that control and future climate experiment runs can be made without one need to consider these non-physical transients. To this end two different techniques are commonly used: (1) Spin-up runs spanning many glacial-interglacial cycles, and (2) spin-up based on assimilation methods for parameter choices which force the model to match observed fields such as surface velocities. (1) is computationally very demanding. Part of the spin-up procedures consists of reconstruction of surface temperature and mass balance fields, and sea-level time series. On the other hand (2), while being computanionally less costly, produces a steady-state temperature field that is most likely not in agreement with the present-day temperature field. We use the hybrid shallow ice/shallow shelf parallel ice sheet model (PISM). The new polythermal thermodynamics of PISM allows to focus especially on spatial variations in pore water pressure and the resulting basal resistance, which is thought to play an important role because it facilitates or impedes sliding. Recently an interferometrically-determined surface velocity data set (Joughin, Smith, Howat, and Scambos, in prep) with high spatial coverage and resolution was added to the SeaRISE data set. We produce spin-up runs using both techniques mentioned above, optimize parameter choices and compare results with the observed surface velocities. To assess the model performance we employ a histogram method.

  2. Enrichment of Fusobacteria in Sea Surface Oil Slicks from the Deepwater Horizon Oil Spill

    PubMed Central

    Gutierrez, Tony; Berry, David; Teske, Andreas; Aitken, Michael D.

    2016-01-01

    The Deepwater Horizon (DWH) oil spill led to rapid microbial community shifts in the Gulf of Mexico, including the formation of unprecedented quantities of marine oil snow (MOS) and of a massive subsurface oil plume. The major taxa that bloomed in sea surface oil slicks during the spill included Cycloclasticus, and to a lesser extent Halomonas, Alteromonas, and Pseudoalteromonas—organisms that grow and degrade oil hydrocarbons aerobically. Here, we show that sea surface oil slicks at DWH contained obligate and facultative anaerobic taxa, including members of the obligate anaerobic phylum Fusobacteria that are commonly found in marine sediment environments. Pyrosequencing analysis revealed that Fusobacteria were strongly selected for when sea surface oil slicks were allowed to develop anaerobically. These organisms have been found in oil-contaminated sediments in the Gulf of Mexico, in deep marine oil reservoirs, and other oil-contaminated sites, suggesting they have putative hydrocarbon-degrading qualities. The occurrence and strong selection for Fusobacteria in a lab-based incubation of a sea surface oil slick sample collected during the spill suggests that these organisms may have become enriched in anaerobic zones of suspended particulates, such as MOS. Whilst the formation and rapid sinking of MOS is recognised as an important mechanism by which a proportion of the Macondo oil had been transported to the sea floor, its role in potentially transporting microorganisms, including oil-degraders, from the upper reaches of the water column to the seafloor should be considered. The presence of Fusobacteria on the sea surface—a highly oxygenated environment—is intriguing, and may be explained by the vertical upsurge of oil that provided a carrier to transport these organisms from anaerobic/micro-aerophilic zones in the oil plume or seabed to the upper reaches of the water column. We also propose that the formation of rapidly-sinking MOS may have re

  3. Sea Ice Induced Glacial/Deglacial Changes in Southern Ocean Surface Structure

    NASA Astrophysics Data System (ADS)

    Abelmann, A.; Gersonde, R.; Knorr, G.; Zhang, X.; Chapligin, B.; Maier, E.; Esper, O.; Lohmann, G.; Meyer, H.; Tiedemann, R.

    2014-12-01

    Glacial/deglacial sea ice variations in the Southern Ocean are suggested to be an important factor impacting ocean's surface structure and biological productivity and thus controlling glacial/interglacial changes in atmospheric CO2. However, the description of involved mechanisms and their implication on nutrient cycling and biological productivity remains incomplete. Isotope measurements on siliceous microorganisms (diatoms and radiolarians) provide a means of reconstructing past changes in nutrient utilization and surface water structure, thus provide information on past biological and physical properties crucial to better describe and model the mechanisms regulating glacial/interglacial variability in CO2 draw down in the Southern Ocean. As diatoms belong to the phytoplankton, they present a sea surface signal. Radiolarians, by contrast, are siliceous zooplankton distributed from surface to deep waters and their stable isotope signals can provide information about deeper water layers. Here, we specify Southern Ocean surface/subsurface contrasts using combined oxygen and silicon isotope measurements of diatom and radiolarian opal obtained from two cores gathered in the sea ice-free Antarctic Zone and northern Polar Front Zone of the Atlantic Southern Ocean. Our records point to a well established glacial spring/summer stratification induced by sea-ice melt. Numerical simulations corroborate this, but also suggest that seasonal stratification was variable with relatively deep mixing that occurred during fall/winter. We discuss various aspects of nutrient utilization in surface and subsurface waters with specific emphasis on the impact of sea ice variations on mixed layer depths and biological productivity during the last glacial and deglacial transition.

  4. Multi-mission mean sea surface and geoid models for ocean monitoring within the GOCINA project

    NASA Astrophysics Data System (ADS)

    Andersen, O. B.; Knudsen, P.; Anne, V. L.

    2004-05-01

    A major goal of the EU project GOCINA (Geoid and Ocean Circulation In the North Atlantic) is to develop tools for ocean monitoring using satellite altimetry combined with satellite gravimetry. Furthermore, the project will determine an accurate geoid in the region between Greenland and the UK and, hereby, create a platform for validation of future GOCE Level 2 data and higher order scientific products. The central quantity bridging the geoid and the ocean circulation is the mean dynamic topography, which is the difference between the mean sea surface and the geoid. The mean dynamic topography provides the absolute reference surface for the ocean circulation. The improved determination of the mean circulation will advance the understanding of the role of the ocean mass and heat transport in climate change. To calculate the best possible synthetic mean dynamic topographies a new mean sea surface (KMS03) has been derived from nine years of altimetric data (1993-2001). The regional geoid has furthermore being updated using GRACE and gravimetric data from a recent airborne survey. New synthetic mean dynamic topography models have been computed from the best available geoid models (EGM96, GRACE, GOCINA) and the present mean sea surface models (i.e. CLS01, GSFC00, KMS03). These models will be compared with state of the art hydrodynamic mean dynamic topography models in the North Atlantic GOCINA area. An extended comparison in the Artic Ocean will also be presented to demonstrate the impact of improved geoid and mean sea surface modeling. Particularly using the GRACE derived geoid models, and the KMS03 mean sea surface.

  5. Correlation between the surface temperature and thickness of Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Frazier, A. H.; Vaccaro, A.; Phillips, S.; Blake, D.; Herman, R. B.

    2012-12-01

    A study was conducted to investigate a possible correlation between the surface temperature and thickness of Arctic sea ice. Surface temperatures were measured with an infrared (IR) sensor while the ice thickness was determined using a capacitively coupled resistivity array. It was postulated that there would be an inverse correlation between the thickness and surface temperature of the sea ice. Thicker sea ice should better insulate the surface from the warmer seawater underneath, causing the surface temperature to vary inversely with sea ice thickness. This study was performed on the Chukchi Sea ice just offshore from Barrow, Alaska. Data was collected along two survey lines, each over 200m long, one parallel and one perpendicular to the shoreline. An IR sensor measured ice surface temperature, and this data was compared to both ground penetrating radar (250MHz and 500MHz) and capacitively coupled resistivity data. Ground penetrating radar was unable to yield a determination of the thickness of the ice. This was not surprising given the ice-to-water transition that starts with solid ice, proceeds through an intervening region of cracked ice and slush, and finally ends with seawater. [1] Resistivity data was collected at approximately 3 points per horizontal meter. With multiple receivers and passes along the survey lines, data was obtained at more than 8 vertical depths in the ice that was approximately 3 meters thick. The resistivity array yielded images indicating the thickness of the sea ice and the location and shape of the ice/water boundary. While the model-dependent nature of resistivity data processing is acknowledged, we have reasonable confidence in the results for the relative thickness of the ice. The temperature of the ice surface was determined via a calibrated (±0.1°C) IR sensor controlled with a data logger. Temperature measurements were collected at approximately 50 points per linear meter. The comparison of the temperature and resistivity data

  6. Impact of surface wind biases on the Antarctic sea ice concentration budget in climate models

    NASA Astrophysics Data System (ADS)

    Lecomte, O.; Goosse, H.; Fichefet, T.; Holland, P. R.; Uotila, P.; Zunz, V.; Kimura, N.

    2016-09-01

    We derive the terms in the Antarctic sea ice concentration budget from the output of three models, and compare them to observations of the same terms. Those models include two climate models from the 5th Coupled Model Intercomparison Project (CMIP5) and one ocean-sea ice coupled model with prescribed atmospheric forcing. Sea ice drift and wind fields from those models, in average over April-October 1992-2005, all exhibit large differences with the available observational or reanalysis datasets. However, the discrepancies between the two distinct ice drift products or the two wind reanalyses used here are sometimes even greater than those differences. Two major findings stand out from the analysis. Firstly, large biases in sea ice drift speed and direction in exterior sectors of the sea ice covered region tend to be systematic and consistent with those in winds. This suggests that sea ice errors in these areas are most likely wind-driven, so as errors in the simulated ice motion vectors. The systematic nature of these biases is less prominent in interior sectors, nearer the coast, where sea ice is mechanically constrained and its motion in response to the wind forcing more depending on the model rheology. Second, the intimate relationship between winds, sea ice drift and the sea ice concentration budget gives insight on ways to categorize models with regard to errors in their ice dynamics. In exterior regions, models with seemingly too weak winds and slow ice drift consistently yield a lack of ice velocity divergence and hence a wrong wintertime sea ice growth rate. In interior sectors, too slow ice drift, presumably originating from issues in the physical representation of sea ice dynamics as much as from errors in surface winds, leads to wrong timing of the late winter ice retreat. Those results illustrate that the applied methodology provides a valuable tool for prioritizing model improvements based on the ice concentration budget-ice drift biases-wind biases

  7. Surface water mass composition changes captured by cores of Arctic land-fast sea ice

    NASA Astrophysics Data System (ADS)

    Smith, I. J.; Eicken, H.; Mahoney, A. R.; Van Hale, R.; Gough, A. J.; Fukamachi, Y.; Jones, J.

    2016-04-01

    In the Arctic, land-fast sea ice growth can be influenced by fresher water from rivers and residual summer melt. This paper examines a method to reconstruct changes in water masses using oxygen isotope measurements of sea ice cores. To determine changes in sea water isotope composition over the course of the ice growth period, the output of a sea ice thermodynamic model (driven with reanalysis data, observations of snow depth, and freeze-up dates) is used along with sea ice oxygen isotope measurements and an isotopic fractionation model. Direct measurements of sea ice growth rates are used to validate the output of the sea ice growth model. It is shown that for sea ice formed during the 2011/2012 ice growth season at Barrow, Alaska, large changes in isotopic composition of the ocean waters were captured by the sea ice isotopic composition. Salinity anomalies in the ocean were also tracked by moored instruments. These data indicate episodic advection of meteoric water, having both lower salinity and lower oxygen isotopic composition, during the winter sea ice growth season. Such advection of meteoric water during winter is surprising, as no surface meltwater and no local river discharge should be occurring at this time of year in that area. How accurately changes in water masses as indicated by oxygen isotope composition can be reconstructed using oxygen isotope analysis of sea ice cores is addressed, along with methods/strategies that could be used to further optimize the results. The method described will be useful for winter detection of meteoric water presence in Arctic fast ice regions, which is important for climate studies in a rapidly changing Arctic. Land-fast sea ice effective fractionation coefficients were derived, with a range of +1.82‰ to +2.52‰. Those derived effective fractionation coefficients will be useful for future water mass component proportion calculations. In particular, the equations given can be used to inform choices made when

  8. On the relationship between water vapor over the oceans and sea surface temperature

    NASA Technical Reports Server (NTRS)

    Stephens, Graeme L.

    1990-01-01

    Monthly mean precipitable water data obtained from passive microwave radiometry were correlated with the National Meteorological Center (NMC) blended sea surface temperature data. It is shown that the monthly mean water vapor content of the atmosphere above the oceans can generally be prescribed from the sea surface temperature with a standard deviation of 0.36 g/sq cm. The form of the relationship between precipitable water and sea surface temperature in the range T (sub s) greater than 18 C also resembles that predicted from simple arguments based on the Clausius-Clapeyron relationship. The annual cycle of the globally integrated mass of Scanning Multichannel Microwave Radiometer (SMMR) water vapor is shown to differ from analyses of other water vapor data in both phase and amplitude and these differences point to a significant influence of the continents on water vapor. Regional scale analyses of water vapor demonstrate that monthly averaged water vapor data, when contrasted with the bulk sea surface temperature relationship developed in this study, reflect various known characteristics of the time mean large-scale circulation over the oceans. A water vapor parameter is introduced to highlight the effects of large-scale motion on atmospheric water vapor. Based on the magnitude of this parameter, it is shown that the effects of large-scale flow on precipitable water vapor are regionally dependent, but for the most part, the influence of circulation is generally less than about + or - 20 percent of the seasonal mean.

  9. Remotely-sensed sea surface temperatuares (SST) of Northeaster Pacific Coastal Zones

    EPA Science Inventory

    Sea surface temperature (SST) is an important indicator of long-term trends and geographical temperature patterns; however there have been relatively few long-term records of SST in near-coastal habitats. In situ SST measurements are irregular in both space and time. Therefore, w...

  10. Six Pseudoalteromonas Strains Isolated from Surface Waters of Kabeltonne, Offshore Helgoland, North Sea

    PubMed Central

    Wichels, Antje; Sullivan, Matthew B.

    2016-01-01

    Draft genomes are presented for 6 Pseudoalteromonas sp. strains isolated from surface waters at Kabeltonne, Helgoland, a long-term ecological research station in the North Sea. These strains contribute knowledge of the genomic underpinnings of a developing model system to study phage-host dynamics of a particle-associated ocean copiotroph. PMID:26868390

  11. Ecoregional analysis of nearshore sea-surface temperature in the North Pacific

    EPA Science Inventory

    Aim Sea surface temperature (SST) has been a parameter widely-identified to be useful to the investigation of marine species distribution, migration, and invasion, especially as SSTs are predicted to be affected by climate change. Here we use a remotely-sensed dataset to focus on...

  12. Determination and analysis of the CSRMSS14 mean sea surface model

    NASA Astrophysics Data System (ADS)

    Kim, H. J.; Tapley, B. D.; Ries, J. C.; Urban, T. J.

    2015-12-01

    As a pivotal role of various applications for ocean sciences, the mean sea surface (MSS) has been developed by merging the sea surface heights (SSH) data sets from different missions for decades. Prior to combining various satellite data, a data adjustment process is applied to make those data sets more homogeneous and consistent. This process is required because there are significant differences in the characteristics and qualities of the measurement corrections, orbit accuracy and systematic biases between the multiple satellite data sets. We have developed a more effective and efficient data adjustment procedure that reduces the long-wavelength errors and systematic biases. A new method is used to obtain an improved SSH data set for selected satellite missions by integrating the SSH gradients with constraints imposed by the Jason-1 mean SSH profile. Using this approach, a total of 5 different satellite SSH data sets (2-year Geosat Exact repeat mission, 6-year ERS-2, 10-year Topex/Poseidon, 8-year Envisat and ERS-1 geodetic mission) were adjusted to the 7-year Jason-1 mean SSH profile. As a result, a new mean sea surface (MSS), named CSRMSS14, was determined from these adjusted satellite data sets. The accuracy of the new MSS was evaluated by comparing with the recent DTU10 global mean sea surface model, and a somewhat independent analysis was performed by comparing Jason-2 altimeter SSH data with DTU10 and CSRMSS14. This presentation describes the approach and the results of the model intercomparisons.

  13. On the relationship between water vapor over the oceans and sea surface temperature

    NASA Technical Reports Server (NTRS)

    Stephens, Graeme L.

    1989-01-01

    Monthly mean precipitable water data obtained from passive microwave radiometry were correlated with the National Meteorological Center (NMC) blended sea surface temperature data. It is shown that the monthly mean water vapor content of the atmosphere above the oceans can generally be prescribed from the sea surface temperature with a standard deviation of 0.36 g/sq cm. The form of the relationship between precipitable water and sea surface temperature in the range T(sub s) greater than 18 C also resembles that predicted from simple arguments based on the Clausius-Clapeyron relationship. The annual cycle of the globally integrated mass of Scanning Multichannel Microwave Radiometer (SMMR) water vapor is shown to differ from analyses of other water vapor data in both phase and amplitude and these differences point to a significant influence of the continents on water vapor. Regional scale analyses of water vapor demonstrate that monthly averaged water vapor data, when contrasted with the bulk sea surface temperature relationship developed in this study, reflect various known characteristics of the time mean large-scale circulation over the oceans. A water vapor parameter is introduced to highlight the effects of large-scale motion on atmospheric water vapor. Based on the magnitude of this parameter, it is shown that the effects of large-scale flow on precipitable water vapor are regionally dependent, but for the most part, the influence of circulation is generally less than about + or - 20 percent of the seasonal mean.

  14. Radial orbit error reduction and sea surface topography determination using satellite altimetry

    NASA Technical Reports Server (NTRS)

    Engelis, Theodossios

    1987-01-01

    A method is presented in satellite altimetry that attempts to simultaneously determine the geoid and sea surface topography with minimum wavelengths of about 500 km and to reduce the radial orbit error caused by geopotential errors. The modeling of the radial orbit error is made using the linearized Lagrangian perturbation theory. Secular and second order effects are also included. After a rather extensive validation of the linearized equations, alternative expressions of the radial orbit error are derived. Numerical estimates for the radial orbit error and geoid undulation error are computed using the differences of two geopotential models as potential coefficient errors, for a SEASAT orbit. To provide statistical estimates of the radial distances and the geoid, a covariance propagation is made based on the full geopotential covariance. Accuracy estimates for the SEASAT orbits are given which agree quite well with already published results. Observation equations are develped using sea surface heights and crossover discrepancies as observables. A minimum variance solution with prior information provides estimates of parameters representing the sea surface topography and corrections to the gravity field that is used for the orbit generation. The simulation results show that the method can be used to effectively reduce the radial orbit error and recover the sea surface topography.

  15. Analysis of near-shore sea surface temperatures in the Northern Pacific

    EPA Science Inventory

    Recent studies report a warming trend in Pacific Ocean temperatures over the last 50 years. However, much less is known about temperature change in the near-coastal environment, which is particularly sensitive to climatic change. In near-shore regions in situ sea surface temper...

  16. Late Miocene to early Pliocene sea surface temperatures from the eastern equatorial Pacific (IODP Site U1338): clumped isotope thermometry on coccolithophore-rich sediments

    NASA Astrophysics Data System (ADS)

    Drury, A.; John, C. M.

    2013-12-01

    The late Miocene to early Pliocene (LM-EP; 8.5-3.5 Ma) was a period of long-term climate stability, only affected by a minor long-term cooling trend, and small long-term ice volume fluctuations. However, it is feasible that the progressive closure of the Central American Seaway (CAS) between 13 and 2.7 Ma impacted on the Pacific equatorial surface environment. The full consequences of this paleoceanographic change are not yet fully understood. Advancing the understanding of the effects of the closure of CAS changes on sea surface temperatures (SST) in the equatorial Pacific region is particularly important, because of the link between equatorial Pacific east-west SST gradients and the El Niño/La Niña - Southern Oscillation (ENSO). Past studies, which show that the thermocline remained deep throughout the late Miocene and into the early Pliocene, argue that this indicates a permanent El Niño state. Permanent El Niño conditions should also be reflected in decreased east to west SST gradients. We aim to reconstruct SSTs in the eastern equatorial Pacific by applyingclumped isotope thermometry on coccolithophore-rich samples. The ';clumped isotope thermometer' (Δ47) reflects the proportion of rare, heavy stable isotopes 13C and 18O bound together in the carbonate crystal lattice, and shows an inverse relationship with temperature. A recent study has shown that coccolithophore calcite shows the same T-Δ47 relationship as inorganic calcite and is not affected by ';vital effects'. The site selected for this study (IODP Site U1338) is located in the eastern equatorial Pacific. The site has high sedimentation rates throughout the targeted interval, with well-preserved foraminifera and coccolithophores. Furthermore, we have correlated the high-resolution benthic stable isotopes (δ13C and δ18O) from Site U1338 to the orbitally tuned benthic isotopes from ODP Site 982 in the North Atlantic, which provides Site U1338 with a high-resolution age model. Preliminary Δ47

  17. Aquarius: An Instrument to Monitor Sea Surface Salinity from Space

    NASA Technical Reports Server (NTRS)

    LeVine, D. M.; Lagerloef, G. S .E.; Colomb, R.; Yueh, S.; Pellerano, F.

    2007-01-01

    Aquarius is a combined passive/active L-band microwave instrument that is being developed to map the salinity field at the surface of the ocean from space. The data will support studies of the coupling between ocean circulation, global water cycle, and climate. Aquarius is part of the Aquarius/SAC-D mission, which is a partnership between the U.S. (National Aeronautics and Space Administration) and Argentina (CONAE). The primary science objective of this mission is to monitor the seasonal and interannual variation of the large-scale features of the surface salinity field in the open ocean with a spatial resolution of 150 km and a retrieval accuracy of 0.2 psu globally on a monthly basis.

  18. The annual cycle in equatorial convection and sea surface temperature

    SciTech Connect

    Mitchell, T.P.; Wallace, J.M. NASA, Goddard Space Flight Center, Greenbelt, MD )

    1992-10-01

    The coupled atmosphere-ocean system in the equatorial eastern Pacific and Atlantic exhibits a distinct annual cycle that is reflected in contrasting conditions at the times of the two equinoxes. The contrasts are so strong that they dominate the annual march of zonally averaged outgoing long wave radiation for the equatorial belt. The March equinox corresponds to the warm season when the equatorial cold tongues in the eastern Pacific and Atlantic area absent. With the onset of summer monsoon convection over Colombia, Central America, and West Africa in May-June, northward surface winds strengthen over the eastern Pacific and Atlantic, the equatorial cold tongues reappear, and the marine convection shifts from the equatorial belt to the intertropical convergence zones (ITCZs) along 8 deg N. On the basis of observational evidence concerning the timing and year-to-year regularity of the surface wind changes during the development of the cold tongues, it is argued that (1) the increase in the northward surface winds in response to the onset of the northern summer monsoon may be instrumental in reestablishing the cold tongues, and (2) positive feedbacks involving both the zonal and meridional wind components contribute to the remarkable robustness of the cold tongue-ITCZs complexes in both oceans. 36 refs.

  19. Microwave radiometer and scatterometer design for the aquarius sea surface Salinity Mission

    NASA Technical Reports Server (NTRS)

    Wilson, William J.; Yueh, Simon H.; Pellerano, Fernando

    2004-01-01

    The measurement of sea surface salinity with L-band microwave radiometers is a very challenging task. Since the L-band brightness temperature variations associated with salinity changes are small, it is necessary to have a very sensitive and stable radiometer. In addition, the corrections for the ocean surface roughness require real time scatterometer measurements. The designs of the Aquarius radiometer and scatterometer are described in this paper.

  20. The impact of variable sea ice roughness on changes in Arctic Ocean surface stress: A model study

    NASA Astrophysics Data System (ADS)

    Martin, Torge; Tsamados, Michel; Schroeder, David; Feltham, Daniel L.

    2016-03-01

    The Arctic sea ice cover is thinning and retreating, causing changes in surface roughness that in turn modify the momentum flux from the atmosphere through the ice into the ocean. New model simulations comprising variable sea ice drag coefficients for both the air and water interface demonstrate that the heterogeneity in sea ice surface roughness significantly impacts the spatial distribution and trends of ocean surface stress during the last decades. Simulations with constant sea ice drag coefficients as used in most climate models show an increase in annual mean ocean surface stress (0.003 N/m2 per decade, 4.6%) due to the reduction of ice thickness leading to a weakening of the ice and accelerated ice drift. In contrast, with variable drag coefficients our simulations show annual mean ocean surface stress is declining at a rate of -0.002 N/m2 per decade (3.1%) over the period 1980-2013 because of a significant reduction in surface roughness associated with an increasingly thinner and younger sea ice cover. The effectiveness of sea ice in transferring momentum does not only depend on its resistive strength against the wind forcing but is also set by its top and bottom surface roughness varying with ice types and ice conditions. This reveals the need to account for sea ice surface roughness variations in climate simulations in order to correctly represent the implications of sea ice loss under global warming.

  1. Rising Mediterranean Sea Surface Temperatures Amplify Extreme Summer Precipitation in Central Europe.

    PubMed

    Volosciuk, Claudia; Maraun, Douglas; Semenov, Vladimir A; Tilinina, Natalia; Gulev, Sergey K; Latif, Mojib

    2016-01-01

    The beginning of the 21st century was marked by a number of severe summer floods in Central Europe associated with extreme precipitation (e.g., Elbe 2002, Oder 2010 and Danube 2013). Extratropical storms, known as Vb-cyclones, cause summer extreme precipitation events over Central Europe and can thus lead to such floodings. Vb-cyclones develop over the Mediterranean Sea, which itself strongly warmed during recent decades. Here we investigate the influence of increased Mediterranean Sea surface temperature (SST) on extreme precipitation events in Central Europe. To this end, we carry out atmosphere model simulations forced by average Mediterranean SSTs during 1970-1999 and 2000-2012. Extreme precipitation events occurring on average every 20 summers in the warmer-SST-simulation (2000-2012) amplify along the Vb-cyclone track compared to those in the colder-SST-simulation (1970-1999), on average by 17% in Central Europe. The largest increase is located southeast of maximum precipitation for both simulated heavy events and historical Vb-events. The responsible physical mechanism is increased evaporation from and enhanced atmospheric moisture content over the Mediterranean Sea. The excess in precipitable water is transported from the Mediterranean Sea to Central Europe causing stronger precipitation extremes over that region. Our findings suggest that Mediterranean Sea surface warming amplifies Central European precipitation extremes. PMID:27573802

  2. Rising Mediterranean Sea Surface Temperatures Amplify Extreme Summer Precipitation in Central Europe

    NASA Astrophysics Data System (ADS)

    Volosciuk, Claudia; Maraun, Douglas; Semenov, Vladimir A.; Tilinina, Natalia; Gulev, Sergey K.; Latif, Mojib

    2016-08-01

    The beginning of the 21st century was marked by a number of severe summer floods in Central Europe associated with extreme precipitation (e.g., Elbe 2002, Oder 2010 and Danube 2013). Extratropical storms, known as Vb-cyclones, cause summer extreme precipitation events over Central Europe and can thus lead to such floodings. Vb-cyclones develop over the Mediterranean Sea, which itself strongly warmed during recent decades. Here we investigate the influence of increased Mediterranean Sea surface temperature (SST) on extreme precipitation events in Central Europe. To this end, we carry out atmosphere model simulations forced by average Mediterranean SSTs during 1970–1999 and 2000–2012. Extreme precipitation events occurring on average every 20 summers in the warmer-SST-simulation (2000–2012) amplify along the Vb-cyclone track compared to those in the colder-SST-simulation (1970–1999), on average by 17% in Central Europe. The largest increase is located southeast of maximum precipitation for both simulated heavy events and historical Vb-events. The responsible physical mechanism is increased evaporation from and enhanced atmospheric moisture content over the Mediterranean Sea. The excess in precipitable water is transported from the Mediterranean Sea to Central Europe causing stronger precipitation extremes over that region. Our findings suggest that Mediterranean Sea surface warming amplifies Central European precipitation extremes.

  3. Rising Mediterranean Sea Surface Temperatures Amplify Extreme Summer Precipitation in Central Europe

    PubMed Central

    Volosciuk, Claudia; Maraun, Douglas; Semenov, Vladimir A.; Tilinina, Natalia; Gulev, Sergey K.; Latif, Mojib

    2016-01-01

    The beginning of the 21st century was marked by a number of severe summer floods in Central Europe associated with extreme precipitation (e.g., Elbe 2002, Oder 2010 and Danube 2013). Extratropical storms, known as Vb-cyclones, cause summer extreme precipitation events over Central Europe and can thus lead to such floodings. Vb-cyclones develop over the Mediterranean Sea, which itself strongly warmed during recent decades. Here we investigate the influence of increased Mediterranean Sea surface temperature (SST) on extreme precipitation events in Central Europe. To this end, we carry out atmosphere model simulations forced by average Mediterranean SSTs during 1970–1999 and 2000–2012. Extreme precipitation events occurring on average every 20 summers in the warmer-SST-simulation (2000–2012) amplify along the Vb-cyclone track compared to those in the colder-SST-simulation (1970–1999), on average by 17% in Central Europe. The largest increase is located southeast of maximum precipitation for both simulated heavy events and historical Vb-events. The responsible physical mechanism is increased evaporation from and enhanced atmospheric moisture content over the Mediterranean Sea. The excess in precipitable water is transported from the Mediterranean Sea to Central Europe causing stronger precipitation extremes over that region. Our findings suggest that Mediterranean Sea surface warming amplifies Central European precipitation extremes. PMID:27573802

  4. Rising Mediterranean Sea Surface Temperatures Amplify Extreme Summer Precipitation in Central Europe.

    PubMed

    Volosciuk, Claudia; Maraun, Douglas; Semenov, Vladimir A; Tilinina, Natalia; Gulev, Sergey K; Latif, Mojib

    2016-08-30

    The beginning of the 21st century was marked by a number of severe summer floods in Central Europe associated with extreme precipitation (e.g., Elbe 2002, Oder 2010 and Danube 2013). Extratropical storms, known as Vb-cyclones, cause summer extreme precipitation events over Central Europe and can thus lead to such floodings. Vb-cyclones develop over the Mediterranean Sea, which itself strongly warmed during recent decades. Here we investigate the influence of increased Mediterranean Sea surface temperature (SST) on extreme precipitation events in Central Europe. To this end, we carry out atmosphere model simulations forced by average Mediterranean SSTs during 1970-1999 and 2000-2012. Extreme precipitation events occurring on average every 20 summers in the warmer-SST-simulation (2000-2012) amplify along the Vb-cyclone track compared to those in the colder-SST-simulation (1970-1999), on average by 17% in Central Europe. The largest increase is located southeast of maximum precipitation for both simulated heavy events and historical Vb-events. The responsible physical mechanism is increased evaporation from and enhanced atmospheric moisture content over the Mediterranean Sea. The excess in precipitable water is transported from the Mediterranean Sea to Central Europe causing stronger precipitation extremes over that region. Our findings suggest that Mediterranean Sea surface warming amplifies Central European precipitation extremes.

  5. Using hyperspectral image enhancement method for small size object detection on the sea surface

    NASA Astrophysics Data System (ADS)

    Yan, Lu; Noro, Naoki; Takara, Yohei; Ando, Fuminori; Yamaguchi, Masahiro

    2015-10-01

    Small size object detection in vast ocean plays an important role in rescues after accident or disaster. One of the promising approach is a hyperspectral imaging system (HIS). However, due to the limitation of HIS sensor's resolution, interested target might occupy only several pixels or less in the image, it's difficult to detect small object, moreover the sun glint of the sea surface make it even more difficult. In this paper, we propose an image analysis technique suitable for the computer aided detection of small objects on the sea surface, especially humans. We firstly separate objects from background by adapting a previously proposed image enhancement method and then apply a linear unmixing method to define the endmember's spectrum. At last, we use spectral angle mapping method to classify presented objects and thus detect small size object. The proposed system provides the following results for supporting the detection of humans and other small objects on the sea surface; an image with spectral color enhancement, alerts of various objects, and the human detection results. This multilayered approach is expected to reduce the oversight, i.e., false negative error. Results of the proposed technique have been compared with existent methods, and our method has successfully enhance the hyperspectral image, and detect small object from the sea surface with high human detection rate, shows the ability to further detection of human in this study). The result are less influenced by the sun glint effects. This study helps recognizing small objects on the sea surface, and it leads to advances in the rescuing system using aircraft equipped HIS technology.

  6. The Impact of Dielectric Constant Model and Surface Reference on Differences Between SMOS and Aquarius Sea Surface Salinity

    NASA Technical Reports Server (NTRS)

    Dinnat, E. P.; Boutin, J.; Yin, X.; LeVine, D. M.

    2014-01-01

    Two ongoing space missions share the scientific objective of mapping the global Sea Surface Salinity (SSS), yet their observations show significant discrepancies. ESA's Soil Moisture and Ocean Salinity (SMOS) and NASA's Aquarius use L-band (1.4 GHz) radiometers to measure emission from the sea surface and retrieve SSS. Significant differences in SSS retrieved by both sensors are observed, with SMOS SSS being generally lower than Aquarius SSS, except for very cold waters where SMOS SSS is the highest overall. Figure 1 is an example of the difference between the SSS retrieved by SMOS and Aquarius averaged over one month and 1 degree in longitude and latitude. Differences are mostly between -1 psu and +1 psu (psu, practical salinity unit), with a significant regional and latitudinal dependence. We investigate the impact of the vicarious calibration and retrieval algorithm used by both mission on these differences.

  7. Surface Elevation, Carbon Sequestration Potential and Rising sea Levels in Estuarine Wetlands

    NASA Astrophysics Data System (ADS)

    Rodríguez, J. F.; Howe, A.; Saco, P. M.

    2007-12-01

    Estuarine wetlands are among the most productive ecosystems on Earth, providing habitat for commercially important fish species and migratory shorebirds, serving as nurseries for many other marine organisms and supporting the productivity of adjacent coastal waters. Typically, these wetlands are driven by tidal hydrodynamics and are net sinks for sediment and soil carbon. Their distribution in the tidal frame depends on a delicate balance between topographic gradient, the rate of vertical soil development, and the rate of sea level change. The complex interactions between hydrodynamics, ecology and soil processes that govern this balance produce positive feedbacks and system self-organization. As complex systems, these wetlands demonstrate resilience under a wide range of conditions but they have been observed to collapse or move to another equilibrium state above certain thresholds. Research at a wetland in the Hunter estuary, southeast Australia has tracked changes in relative sea level and surface elevation in mangrove and saltmarsh wetlands over a five year period (2002- 2006) and soil carbon over a two year period (2005-2006). Mangrove surface elevation was strongly correlated with relative sea level (R2=0.715, p=0.004) but there was no correlation between relative sea level and saltmarsh surface elevation (R2=0.093, p=0.424). Soil carbon levels were high in both vegetation types (% loss on ignition of 16.2% and 18.8% for mangrove and saltmarsh soils, respectively) and not significantly different (ANOVA F=1.36, p=0.270). A 16% increase in soil carbon was recorded in each vegetation type over the period 2005-2006. Mean annual sea level rose by 55 mm and net annual precipitation (rainfall minus evaporation) fell by 189 mm over the same period. The ability of mangrove to respond rapidly to changes in relative sea level and the indicative positive trend between soil carbon and relative sea level suggest that this wetland type is both resilient to future sea level

  8. Comparison of ECMWF surface meteorology and buoy observations in the Ligurian Sea

    NASA Astrophysics Data System (ADS)

    Bozzano, R.; Siccardi, A.; Schiano, M.; Borghini, M.; Castellari, S.

    2004-02-01

    . Since numerical weather prediction (NWP) models are usually used to force ocean circulation models, it is important to investigate their skill in reproducing surface meteorological parameters in open sea conditions. Near-surface meteorological data (air temperature, relative humidity, barometric pressure, wind speed and direction) have been acquired from several sensors deployed on an offshore large spar buoy in the Ligurian Sea (Northern Mediterranean Sea) from February to December 2000. The buoy collected 7857 valid records out of 8040 during 335 days at sea. These observations have been compared with data from NWP models and specifically, the outputs of the ECMWF analysis in the two grid points closest to the buoy position. Hourly data acquired by the buoy have been undersampled to fit the data set of the model composed by values computed at the four synoptic hours. For each mentioned meteorological parameter an analysis has been performed by evaluating instantaneous synoptic differences, distributions, daily and annual variations and related statistics. The comparison shows that the model reproduces correctly the baric field while significant differences result for the other variables, which are more affected by local conditions. This suggests that the observed discrepancies may be due to the poor resolution of the model that probably is not sufficient to appropriately discriminate between land and ocean surfaces in a small basin such as the Ligurian Sea and to take into account local peculiarities. The use of time- and space-averaged model data reduces the differences with respect to the in situ observations, thus making the model data usable for analysis with minor requirements about time and space resolution. Although this comparison is strongly limited and we cannot exclude measurement errors, its results suggest a great caution in the use of the model data, especially at high frequency resolution. They may lead to incorrect estimates of atmospheric

  9. Sea, ice and surface water circulation, Alaskan Continental Shelf

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    The author has identified the following significant results. Two cruises were conducted in Cook Inlet to obtain ground truth. Forty-seven stations during 22-23 August and 68 stations during 25-29 September 1972 were occupied and temperature, salinity, percent light transmission, and suspended load of surface waters obtained. Similar data at various depths was also obtained at selected stations. Cook Inlet is an estuary with complex mixing of river discharges and ocean water. The Upper Cook Inlet shows a gradual and systematic decrease in salinity, however, west of Kenai the mixing of waters is complex. The sediments in suspension originating at the head of the inlet generally settle out east of Kenai and Drift River. Sediment load in suspension decreased gradually from 1700 mg/1 near Anchorage to about 50 mg/1 in the Narrows. In the Lower Cook Inlet the suspended load varied between 1-10 mg/1. Surface waters with sediments in suspension and ocean water with relatively lower sediment concentration are clearly discernible in ERTS-1 images obtained during September 18, 1972 pass over Cook Inlet. The movement and mixing of these waters can also be delineated in the images.

  10. Iceberg ploughmark features on bottom surface of the South-Eastern Baltic Sea

    NASA Astrophysics Data System (ADS)

    Dorokhov, Dmitry; Sivkov, Vadim; Dorokhova, Evgenia; Krechik, Viktor

    2016-04-01

    A detail swath bathymetry, side-scan sonar and acoustic profiling combined with sediment sampling during the 64th cruise of RV "Academic Mstislav Keldysh" (October 2015) allowed to identify new geomorphological features of the South-Eastern Baltic Sea bottom surface. The extended chaotic ploughmarks (furrows) in most cases filled with thin layer of mud were discovered on surface of the Gdansk-Gotland sill glacial deposits. They are observed on the depth of more than 70 m and have depth and width from 1 to 10 m. Most of them are v- or u-shaped stepped depressions. The side-scan records of similar geomorpholoical features are extensively reported from Northern Hemisphere and Antarctica (Goodwin et al., 1985; Dowdeswell et al., 1993). Ploughmarks are attributed to the action of icebergs scouring into the sediment as they touch bottom. We are suggest that furrows discovered in the South-Eastern Baltic Sea are also the result of iceberg scouring during the Baltic Ice Lake stage (more than 11 600 cal yr BP (Bjorck, 2008)). This assumption confirmed by occurrence of fragmental stones and boulders on the sea bottom surface which are good indicators of iceberg rafting (Lisitzin, 2003). Ice ploughmarks at sea bottom surface were not occurred before in the South-Eastern Baltic Sea. The study was financed by Russian Scientific Fund, grant number 14-37-00047. References Bjorck S. The late Quaternary development of the Baltic Sea Basin. In: The BACC Author Team (eds) Assessment of climate change for the Baltic Sea Basin. Springer, Berlin, Heidelberg. 2008. Dowdeswell J. A., Villinger H., Whittington R. J., Marienfeld P. Iceberg scouring in Scoresby Sund and on the East Greenland continental shelf // Marine Geology. V. 111. N. 1-2. 1993. P. 37-53. Goodwin C. R., Finley J. C., Howard L. M. Ice scour bibliography. Environmental Studies Revolving Funds Report No. 010. Ottawa. 1985. 99 pp. Lisitzin A. P. Sea-Ice and Iceberg Sedimentation in the Ocean: Recent and Past. Springer

  11. Use of a spacecraft borne altimeter for determining the mean sea surface and the geopotential

    NASA Technical Reports Server (NTRS)

    Kahn, W. D.; Bryan, J. W.

    1972-01-01

    An experiment is proposed to test a first generation spacecraft-borne radar altimeter's capability to measure the topography of the sea surface. The initial radar altimeter will have an instrumental error of one meter and an overall accuracy to two to five meters. This instrument will thus improve the accuracy of the geoid from the present 10 to 20 meters to better than 5 meters. In order to detect storm surges, tidal forces, and ocean currents, an altimeter with an overall accuracy of at least ?1 meter will be required. The overall accuracy of the initial radar altimeter will thus primarily provide geodetic information and possible oceanographic information such as sea state.

  12. Low-frequency variability of surface air temperature over the Barents Sea: causes and mechanisms

    NASA Astrophysics Data System (ADS)

    van der Linden, Eveline C.; Bintanja, Richard; Hazeleger, Wilco; Graversen, Rune G.

    2016-08-01

    The predominant decadal to multidecadal variability in the Arctic region is a feature that is not yet well-understood. It is shown that the Barents Sea is a key region for Arctic-wide variability. This is an important topic because low-frequency changes in the ocean might lead to large variations in the sea-ice cover, which then cause massive changes in the ocean-atmosphere heat exchanges. Here we describe the mechanism driving surface temperatures and heat fluxes in the Barents Sea based primarily on analyzes of one global coupled climate model. It is found that the ocean drives the low-frequency changes in surface temperature, whereas the atmosphere compensates the oceanic transport anomalies. The seasonal dependence and the role of individual components of the ocean-atmosphere energy budget are analyzed in detail, showing that seasonally-varying climate mechanisms play an important role. Herein, sea ice is governing the seasonal response, by acting as a lid that opens and closes during warm and cold periods, respectively, thereby modulating the surface heat fluxes.

  13. Sea Surface Temperature Coupling to Madden-Julian Oscillations over the Indonesian Maritime Continent

    NASA Astrophysics Data System (ADS)

    Napitu, A. M.; Gordon, A. L.; Pujiana, K.

    2014-12-01

    The intraseasonal SST characteristics within the Indonesian Seas and their responses to the Madden-Julian Oscillations [MJO] are examined through analyses of observed and reanalysis datasets. Intraseasonal variation accounts for about 30% of SST variability, with the strongest signature is observed in Banda and Timor seas. The MJO signature in SST is evident in the form of energy peak at 35-45 days, amplification during the Northwest Monsoon (boreal winter), and eastward propagation. SST responds to sea-air heat flux associated with MJO with net heat flux into the ocean (atmosphere) characterizing the suppressed (active) phase of MJO. The influence of MJO on Banda Sea SST is greatest during La Niña periods, which are favorable for deeper thermocline conditions, which diminish the role of ocean processes driving vertical heat transfer between subsurface and surface layers. Diminished influence of ocean processes results in dominance of surface heat fluxes associated with MJO in governing intraseasonal SST variability. During El Niño, the role of ocean processes is favorable to mediate heat transfer between lower and upper layer of the ocean surface as thermocline is shallower. The ocean component heat fluxes then compete with MJO forced heat fluxes in governing SST variability as indicated by less pronounced eastward propagation.

  14. [Variation characteristics and controlling factors of heavy metals in the South Yellow Sea surface seawaters].

    PubMed

    He, Zhi-Peng; Song, Jin-Ming; Zhang, Nai-Xing; Xu, Ya-Yan; Zheng, Guo-Xia; Zhang, Peng

    2008-05-01

    Based on the 8 cruises data of surface seawater heavy metals and other related environmental factors from 1997 to 2004 of the South Yellow Sea (SYS), distribution patterns, mechanisms controlling the distributions and pollution levels of heavy metals (As, Cd, Cu, Hg, Pb, Zn) were studied with the data of 2003-10, and 8-year-fluctuation trends of heavy metals were also discussed. The average concentrations of heavy metals in surface seawater were 2.33, 0.078, 1.41, 0.003 6, 0.37, 6.21 microg/L respectively. The average concentrations showed a relatively stable trend in 8 years, except Zn's distinct upward tendency. The distribution patterns corresponded to the distance away from the coastline,that was, the content of heavy metals (except Pb) was low in central area while high inshore. Those were responses of human activity in the marginal sea, however, in some local areas, Pb was controlled by atmospheric deposition, Cd was relative to pH and salinity, Hg was related to organic carbon, Cu and Zn were influenced by runoff and drainage, and the resuspending of sediments played important roles on the content and distribution of As. Compared to the Marine Water Quality Standard of China, heavy metals indicated that SYS was a first class sea, and Ecological Risk Index analysis showed that SYS was a low ecological risk sea. In conclusion, seawater quality of heavy metals in SYS surface seawater is relatively good in general.

  15. Numerical reconstruction of trajectory of small-size surface drifter in the Mediterranean sea. Reconstruction of surface drift in the Mediterranean sea

    NASA Astrophysics Data System (ADS)

    Shchekinova, Elena Y.; Kumkar, Yogesh; Coppini, Giovanni

    2016-02-01

    In this study, we addressed the effects of wind-induced drift on Lagrangian trajectories of surface sea objects using high-resolution ocean forecast and atmospheric data. Application of stochastic Leeway model for prediction of trajectories drift was considered for the numerical reconstruction of the Elba accident that occurred during the period 21.06.2009-22.06.2009: a person on an inflatable raft was lost in the vicinity of the Elba Island coast; from the initial position, the person on a raft drifted southwards in the open sea and later he was found on a partially deflated raft during rescue operation. For geophysical forcing, we used high-resolution currents from the Mediterranean Forecasting System and atmospheric wind from the European Centre for Medium-Range Weather Forecasts. To investigate the effect of wind on trajectory behavior, numerical simulations were performed using different categories of drifter-like particles similar to a person on an inflatable raft. An algorithm of spatial clustering was used to differentiate the most probable search areas with a high density of particles. Our results showed that the simulation scenarios using particles with characteristics of draft-limited sea drifters provided better prediction of an observed trajectory in terms of the probability density of particles.

  16. Impact of the Sun on Remote Sensing of Sea Surface Salinity from Space

    NASA Technical Reports Server (NTRS)

    LeVine, David M; Abraham, Saji; Wentz, F; Lagerloef, G S

    2005-01-01

    The sun is a sufficiently strong source of radiation at L-band to be an important source of interference for radiometers on future satellite missions such as SMOS, Aquarius, and Hydros designed to monitor soil moisture and sea surface salinity. Radiation from the sun can impact passive remote sensing systems in several ways, including line-of-sight radiation that comes directly from the sun and enters through antenna side lobes and radiation that is reflected from the surface to the radiometer. Examples are presented in the case of Aquarius, a pushbroom radiometer with three beams designed to monitor sea surface salinity. Near solar minimum, solar contamination is not a problem unless the sun enters near the main beam. But near solar maximum, contamination from the sun equivalent to a change of salinity on the order of 0.1 psu can occur even when the signal enters in sidelobes far from the main beam.

  17. Multisensor satellite data integration for sea surface wind speed and direction determination

    NASA Technical Reports Server (NTRS)

    Glackin, D. L.; Pihos, G. G.; Wheelock, S. L.

    1984-01-01

    Techniques to integrate meteorological data from various satellite sensors to yield a global measure of sea surface wind speed and direction for input to the Navy's operational weather forecast models were investigated. The sensors were launched or will be launched, specifically the GOES visible and infrared imaging sensor, the Nimbus-7 SMMR, and the DMSP SSM/I instrument. An algorithm for the extrapolation to the sea surface of wind directions as derived from successive GOES cloud images was developed. This wind veering algorithm is relatively simple, accounts for the major physical variables, and seems to represent the best solution that can be found with existing data. An algorithm for the interpolation of the scattered observed data to a common geographical grid was implemented. The algorithm is based on a combination of inverse distance weighting and trend surface fitting, and is suited to combing wind data from disparate sources.

  18. Surface current patterns suggested by suspended sediment distribution over the outer continental margin, Bering Sea

    USGS Publications Warehouse

    Karl, Herman A.; Carlson, P.R.

    1987-01-01

    Samples of total suspended matter (TSM) were collected at the surface over the northern outer continental margin of the Bering Sea during the summers of 1980 and 1981. Volume concentrations of surface TSM averaged 0.6 and 1.1 mg l-1 for 1980 and 1981, respectively. Organic matter, largely plankton, made up about 65% of the near-surface TSM for both years. Distributions of TSM suggested that shelf circulation patterns were characterized either by meso- and large- scale eddies or by cross-shelf components of flow superimposed on a general northwesterly net drift. These patterns may be caused by large submarine canyons which dominate the physiography of this part of the Bering Sea continental margin. ?? 1987.

  19. Modeling the spectrum of infrasonic hydroacoustic radiation generated by the sea surface under storm conditions

    NASA Astrophysics Data System (ADS)

    Zapevalov, A. S.; Pokazeev, K. V.

    2016-09-01

    Generation of infrasonic radiation into a water medium by sea surface waves is analyzed. The analysis is carried out for the situation in which the infrasound is generated by surface waves with frequencies close to those of dominant waves. The presence of two wave systems on the sea surface is assumed: swell and wind waves. It is shown that if the frequencies of spectral peaks of wind waves and swell diverge by 20%, the maximum value of the radiation spectrum decreases by approximately 40% (if the general directions of the two wave systems are oriented strictly towards each other). A deviation of the general directions of the two wave systems from the opposite direction by 45° leads to a decrease in the maximum value of the radiation spectrum by more than two times.

  20. Global Changes in the Sea Ice Cover and Associated Surface Temperature Changes

    NASA Astrophysics Data System (ADS)

    Comiso, Josefino C.

    2016-06-01

    The trends in the sea ice cover in the two hemispheres have been observed to be asymmetric with the rate of change in the Arctic being negative at -3.8 % per decade while that of the Antarctic is positive at 1.7 % per decade. These observations are confirmed in this study through analyses of a more robust data set that has been enhanced for better consistency and updated for improved statistics. With reports of anthropogenic global warming such phenomenon appears physically counter intuitive but trend studies of surface temperature over the same time period show the occurrence of a similar asymmetry. Satellite surface temperature data show that while global warming is strong and dominant in the Arctic, it is relatively minor in the Antarctic with the trends in sea ice covered areas and surrounding ice free regions observed to be even negative. A strong correlation of ice extent with surface temperature is observed, especially during the growth season, and the observed trends in the sea ice cover are coherent with the trends in surface temperature. The trend of global averages of the ice cover is negative but modest and is consistent and compatible with the positive but modest trend in global surface temperature. A continuation of the trend would mean the disappearance of summer ice by the end of the century but modelling projections indicate that the summer ice could be salvaged if anthropogenic greenhouse gases in the atmosphere are kept constant at the current level.

  1. Mean sea surface and variability of the Gulf of Mexico using Geosat altimetry data

    NASA Technical Reports Server (NTRS)

    Leben, Robert R.; Born, George H.; Fox, Chad A.; Thompson, Dana J.

    1990-01-01

    Geosat Exact Repeat Mission (ERM) altimetric measurements of the sea surface height in the Gulf of Mexico are used to determine the mean sea surface height with respect to the ellipsoid and mesoscale variability along Geosat ground tracks in the gulf for the time period from November 8, 1986 to November 25, 1988. A mean surface generated using the Geosat ERM along-track mean is calculated and contrasted with a previously derived mean surface determined using GEOS 3 and Seasat crossover differences. This provides a first look at the variability in the mean between the time periods of 1987-1988 and 1975-1978. In addition, the along-track mesoscale variability time series has been produced from the Geosat ERM data set by using a robust orbit-error removal algorithm to determine the variability of the sea-surface height with respect to the along-track mean. Good qualitative and quantitative agreement with previous in situ observations in the region is found. This study demonstrates the potential of satellite altimetry for oceanographic studies of the Gulf of Mexico.

  2. Pliocene-Pleistocene evolution of sea surface and intermediate water temperatures from the southwest Pacific

    NASA Astrophysics Data System (ADS)

    McClymont, Erin L.; Elmore, Aurora C.; Kender, Sev; Leng, Melanie J.; Greaves, Mervyn; Elderfield, Henry

    2016-06-01

    Over the last 5 million years, the global climate system has evolved toward a colder mean state, marked by large-amplitude oscillations in continental ice volume. Equatorward expansion of polar waters and strengthening temperature gradients have been detected. However, the response of the mid latitudes and high latitudes of the Southern Hemisphere is not well documented, despite the potential importance for climate feedbacks including sea ice distribution and low-high latitude heat transport. Here we reconstruct the Pliocene-Pleistocene history of both sea surface and Antarctic Intermediate Water (AAIW) temperatures on orbital time scales from Deep Sea Drilling Project Site 593 in the Tasman Sea, southwest Pacific. We confirm overall Pliocene-Pleistocene cooling trends in both the surface ocean and AAIW, although the patterns are complex. The Pliocene is warmer than modern, but our data suggest an equatorward displacement of the subtropical front relative to present and a poleward displacement of the subantarctic front of the Antarctic Circumpolar Current (ACC). Two main intervals of cooling, from ~3 Ma and ~1.5 Ma, are coeval with cooling and ice sheet expansion noted elsewhere and suggest that equatorward expansion of polar water masses also characterized the southwest Pacific through the Pliocene-Pleistocene. However, the observed trends in sea surface temperature and AAIW temperature are not identical despite an underlying link to the ACC, and intervals of unusual surface ocean warmth (~2 Ma) and large-amplitude variability in AAIW temperatures (from ~1 Ma) highlight complex interactions between equatorward displacements of fronts associated with the ACC and/or varying poleward heat transport from the subtropics.

  3. Evidence for Recent Surface/Atmosphere Feedbacks in the East Siberian Sea during Spring

    NASA Astrophysics Data System (ADS)

    Overland, J. E.; Bond, N. A.; Wang, M.

    2005-12-01

    Arctic climate responds to multiple factors including intrinsic variability in atmospheric circulation, internal feedbacks and external forcing, in unknown proportion. The present analysis quantifies the contribution of the anomalous atmospheric circulation relative to the anomalous surface heating for the East Siberian Sea during the springs (March-May) of 200-2005, a period of surface air temperatures that were 4-6 C warmer than normal. The circulation for this period featured an anomalous lower to middle tropospheric high pressure ridge extending from Alaska to the North Pole and a low pressure trough extending from the Sea of Okhotsk to west-central Siberia. This geopotential height anomaly pattern bears little resemblance to either of the two main modes of northern hemispheric climate variability, the Arctic Oscillation or its Pacific counterpart, the Pacific North American pattern. Horizontal temperature advection due to the anomalous southerly flow accounts for roughly 10 W/m2 of anomalous heating in the East Siberian Sea. This heating appears to have been reinforced in the planetary boundary layer by anomalous surface heating of roughly 10-20 W/m2, which is consistent with systematically thin sea ice in recent springs. Increased temperatures in the lower atmosphere have an impact on the motion field through the thermal wind effect. An interesting implication is that the atmosphere may be more sensitive to thin ice conditions in spring than to ice-free conditions in summer. The large-scale atmospheric circulation could shift back to a pattern favoring northerly flow anytime in the future; it will be interesting to see the regional response in sea ice and surface temperature if this happens.

  4. The Atmospheric Response to Surface Stress Induced by the Kuroshio Current in the East China Sea

    NASA Astrophysics Data System (ADS)

    Takatama, K.; Schneider, N.

    2015-12-01

    Frontal air-sea interaction is typically cast in terms of the thermal impact of ocean fronts on the atmosphere. The effect of ocean current drag on the lower troposphere is assumed to be small, but of interest as it isolates the modulation of the surface stress independent of the thermally induced modulation of the boundary layer stability and hydrostatic pressure. Here, we use a regional atmospheric model to investigate the impact of drag induced by the Kuroshio Current in the winter East China Sea on the overlying atmosphere. The ocean current enhances the wind stress curl compared to the impacts of the associated sea surface temperature (SST) front alone. In addition, the stress across the current direction, generating the stress divergence, is also enhanced weakly via the atmospheric adjustment to the oceanic curl. These modifications change the linear relationships between the wind stress curl (divergence) onto SST Laplacian or onto crosswind (downwind) SST gradient, known as coupling coefficients. The influence of the current induced drag beyond the sea surface is affected by advection and weaker than expected from Ekman pumping alone, but some clear signatures are found: sea surface pressure decreases just over the current axis, and precipitation increases over the southeast side of the current corresponding to the induced wind convergence. A linear reduced gravity model is used to explain the dynamics of the response in the marine atmospheric boundary layer. Transfer function, a kind of a coupling coefficient which is expanded in wave-number space, indicates the strength of the response as a function of the ocean current speed depending on the spatial scale.

  5. Sea surface carbon dioxide at the Georgia time series site (2006-2007): Air-sea flux and controlling processes

    NASA Astrophysics Data System (ADS)

    Xue, Liang; Cai, Wei-Jun; Hu, Xinping; Sabine, Christopher; Jones, Stacy; Sutton, Adrienne J.; Jiang, Li-Qing; Reimer, Janet J.

    2016-01-01

    Carbon dioxide partial pressure (pCO2) in surface seawater was continuously recorded every three hours from 18 July 2006 through 31 October 2007 using a moored autonomous pCO2 (MAPCO2) system deployed on the Gray's Reef buoy off the coast of Georgia, USA. Surface water pCO2 (average 373 ± 52 μatm) showed a clear seasonal pattern, undersaturated with respect to the atmosphere in cold months and generally oversaturated in warm months. High temporal resolution observations revealed important events not captured in previous ship-based observations, such as sporadically occurring biological CO2 uptake during April-June 2007. In addition to a qualitative analysis of the primary drivers of pCO2 variability based on property regressions, we quantified contributions of temperature, air-sea exchange, mixing, and biological processes to monthly pCO2 variations using a 1-D mass budget model. Although temperature played a dominant role in the annual cycle of pCO2, river inputs especially in the wet season, biological respiration in peak summer, and biological production during April-June 2007 also substantially influenced seawater pCO2. Furthermore, sea surface pCO2 was higher in September-October 2007 than in September-October 2006, associated with increased river inputs in fall 2007. On an annual basis this site was a moderate atmospheric CO2 sink, and was autotrophic as revealed by monthly mean net community production (NCP) in the mixed layer. If the sporadic short productive events during April-May 2007 were missed by the sampling schedule, one would conclude erroneously that the site is heterotrophic. While previous ship-based pCO2 data collected around this buoy site agreed with the buoy CO2 data on seasonal scales, high resolution buoy observations revealed that the cruise-based surveys undersampled temporal variability in coastal waters, which could greatly bias the estimates of air-sea CO2 fluxes or annual NCP, and even produce contradictory results.

  6. Culturing-based Temperature Calibration of a Genetically Distinct, Alkenone-producing Haptophyte Species isolated from Lake George, ND

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Andersen, R. A.; Huang, Y.; Amaral-Zettler, L. A.

    2014-12-01

    Lacustrine alkenones are rapidly becoming an important tool for continental paleoclimate reconstructions. However, DNA sequencing of 18S ribosomal RNA marker genes has uncovered multiple species of haptophytes in different lakes. To date, there are only two isolated lacustrine species Chrysotila lamellosa and Isochrysis galbana available for culture studies. In our study, we report the isolation of a new haptophyte species from Lake George (LG) that, based on analyses of partial large subunit rRNA gene sequences, is genetically distinct from both Chrysotila lamellosa and Isochrysis galbana. We examined alkenone unsaturation index UK37 values for the LG species at 4°C, 10°C, 15°C, 20°C and 25°C as a function of temperature in a culture experiment. The temperature sensitivity of the new species was significantly higher than previously cultured Isochrysis galbana and Chrysotila lamellosa strains, with a slope that was 25 to 100 % higher. We found that the best linear relationship was obtained when two double-bond alkenones were excluded from the calibration (we developed an index termed UK''37 = [C37:4] / [C37:3+C37:4]). In particular, UK''37 is more linear to the growth temperature than UK37 at low (4-10°C) and high (20-25°C) temperature ranges. Our experiments show that both UK37 and UK''37 of this new alkenone-produced species is strongly controlled by culture temperature and can be used for paleoclimate reconstruction. However, we recommend the use of UK''37 index to reconstruct temperature if the haptophyte's growing environment falls within temperature extremes (4-10°C and 20-25°C). This newly cultivated species broadens our ability of applying lacustrine haptophyte calibrations to continental paleothermometry.

  7. Improving Surface Mass Balance Over Ice Sheets and Snow Depth on Sea Ice

    NASA Technical Reports Server (NTRS)

    Koenig, Lora Suzanne; Box, Jason; Kurtz, Nathan

    2013-01-01

    Surface mass balance (SMB) over ice sheets and snow on sea ice (SOSI) are important components of the cryosphere. Large knowledge gaps remain in scientists' abilities to monitor SMB and SOSI, including insufficient measurements and difficulties with satellite retrievals. On ice sheets, snow accumulation is the sole mass gain to SMB, and meltwater runoff can be the dominant single loss factor in extremely warm years such as 2012. SOSI affects the growth and melt cycle of the Earth's polar sea ice cover. The summer of 2012 saw the largest satellite-recorded melt area over the Greenland ice sheet and the smallest satellite-recorded Arctic sea ice extent, making this meeting both timely and relevant.

  8. Sea Surface Wakes Observed by Spaceborne SAR in the Offshore Wind Farms

    NASA Astrophysics Data System (ADS)

    Li, Xiaoming; Lehner, Susanne; Jacobsen, Sven

    2014-11-01

    In the paper, we present some X-band spaceborne synthetic aperture radar (SAR) TerraSAR-X (TS-X) images acquired at the offshore wind farms in the North Sea and the East China Sea. The high spatial resolution SAR images show different sea surface wake patterns downstream of the offshore wind turbines. The analysis suggests that there are major two types of wakes among the observed cases. The wind turbine wakes generated by movement of wind around wind turbines are the most often observed cases. In contrast, due to the strong local tidal currents in the near shore wind farm sites, the tidal current wakes induced by tidal current impinging on the wind turbine piles are also observed in the high spatial resolution TS-X images. The discrimination of the two types of wakes observed in the offshore wind farms is also described in the paper.

  9. Role of Sea Surface Warming in Triggering Amplification of Coastal Rainfall Extremes

    NASA Astrophysics Data System (ADS)

    Meredith, Edmund; Semenov, Vladimir; Maraun, Douglas; Park, Wonsun; Chernokulsky, Alexander

    2015-04-01

    Whether recent changes in the occurrence of meteorological extremes are attributable to a warmer climate remains a challenging question. One area where the potential for extreme summertime convective precipitation has grown recently, along with substantial sea surface temperature (SST) increase, is the Black Sea and Mediterranean (BSM) region. To study mechanisms through which SST increase may impact BSM convective extremes, we take the July 2012 precipitation extreme near the Black Sea town of Krymsk as a recent showcase example. The event was related to a slow moving low pressure system crossing the eastern Black Sea, advecting warm and moist air towards the coast. Two waves of convection resulted in precipitation totals that dwarfed all previous events in the instrumental record, dating back to the 1930s, and over 170 deaths. The synoptic environment which led to this event is typical of that found with intense summertime precipitation in the BSM region. We carry out ensemble sensitivity experiments over an eastern Black Sea domain with the WRF regional model, using multiply nested sub-domains, increasing to 600 m convection resolving resolution. The model's ability to reproduce the event with observed SST forcing is first verified, before a series of additional ensembles with altered SST is created. These ensembles consist of subtracting (adding) the 1982 - 2012 trend in Black Sea SST from (to) the observed 2012 SST field in 20% increments, giving a total of 11 ensembles whose SST differ from the observed field by between -100% and +100% of the warming trend. We demonstrate that such an intense precipitation event would not have been possible without the recent Black Sea warming. The increased SST enhances low-level instability, allowing deep convection to be triggered and causing a more than 300% increase in precipitation. Additionally, a highly nonlinear precipitation response to incrementally increasing SST suggests that Black Sea SSTs have exceeded a

  10. The Sea Surface Temperature Variation during the Spring Tide and Neap Tide in the South China Sea

    NASA Astrophysics Data System (ADS)

    Huang, Shih-Jen; Kuo, Nan-Jung; Ho, Chung-Ru; Lo, Yao-Tsai

    2016-04-01

    The sea surface temperature (SST) data of MODIS/Terra (Moderate-resolution Imaging Spectroradiometer) are used to analyze the SST difference between the spring tide and the neap tide in the South China Sea (SCS) from 2001 to 2013. The 4 stations from north to south in the SCS are used to investigate the variation of SST. The results show the lowest SST found on January and the highest SST found on June. The standard deviation of SST in shallow regions (St. 1 and St. 4) are larger than the deep regions (St. 2 and St. 3). During the winter and spring the standard deviation of SST at the neap tide are greater than the spring tide period. From the later winter to early summer, the SST during the neap tide period is greater than the spring tide period. They are more obvious in the shallow regions. Meanwhile the influence of tide action in the shallow regions is greater than it in the deep regions.

  11. Application of a sea surface temperature front composite algorithm in the Bohai, Yellow, and East China Seas

    NASA Astrophysics Data System (ADS)

    Ping, Bo; Su, Fenzhen; Meng, Yunshan; Du, Yunyan; Fang, Shenghui

    2016-05-01

    The oceanic front is a narrow zone in which water properties change abruptly within a short distance. The sea surface temperature (SST) front is an important type of oceanic front, which plays a signifi cant role in many fi elds including fi sheries, the military, and industry. Satellite-derived SST images have been used widely for front detection, although these data are susceptible to infl uence by many objective factors such as clouds, which can cause missing data and a reduction in front detection accuracy. However, front detection in a single SST image cannot fully refl ect its temporal variability and therefore, the long-term mean frequency of occurrence of SST fronts and their gradients are often used to analyze the variations of fronts over time. In this paper, an SST front composite algorithm is proposed that exploits the frontal average gradient and frequency more eff ectively. Through experiments based on MODIS Terra and Aqua data, we verifi ed that fronts could be distinguished better by using the proposed algorithm. Additionally through its use, we analyzed the monthly variations of fronts in the Bohai, Yellow, and East China Seas, based on Terra data from 2000 to 2013.

  12. Scale effect and optimum relations for sea surface planning

    NASA Technical Reports Server (NTRS)

    Sedov, L.

    1947-01-01

    From the general dimensional and mechanical similarity theory it follows that a condition of steady motion of a given shape\\bottom with constant speed on the surface of water is determined by four nondimensional parameters. By considering the various systems of independent parameters which are applied in theory and practice and special tests, there is determined their mutual relations and their suitability as planning characteristics. In studying the scale effect on the basis of the Prnndtl formula for the friction coefficient for a turbulent condition the order of magnitude is given of the error in applying the model data to full scale in the case of a single-step bottom For a bottom of complicated shape it is shown how from the test data of the hydrodynamic characteristics for one speed with various loads, or one load with various speeds, there may be obtained by simple computation with good approximation the hydrodynamic characteristics for a different speed or for a different load. (These considerations may be of use in solving certain problems on the stability of planning.) This permits extrapolating the curve of resistance against speed for large speeds inaccessible in the tank tests or for other loads which were not tested. The data obtained by computation are in good agreement with the test results. Problems regarding the optimum trim angle or the optimum width in the case of planning of a flat plate are considered from the point of view of the minimum resistance for a given load on the water and planning speeds. Formulas and graphs are given for the optimum value of the planning coefficient and the corresponding values of the trim angle and width of the flat plate.

  13. Impact of Surface Roughness on AMSR-E Sea Ice Products

    NASA Technical Reports Server (NTRS)

    Stroeve, Julienne C.; Markus, Thorsten; Maslanik, James A.; Cavalieri, Donald J.; Gasiewski, Albin J.; Heinrichs, John F.; Holmgren, Jon; Perovich, Donald K.; Sturm, Matthew

    2006-01-01

    This paper examines the sensitivity of Advanced Microwave Scanning Radiometer (AMSR-E) brightness temperatures (Tbs) to surface roughness by a using radiative transfer model to simulate AMSR-E Tbs as a function of incidence angle at which the surface is viewed. The simulated Tbs are then used to examine the influence that surface roughness has on two operational sea ice algorithms, namely: 1) the National Aeronautics and Space Administration Team (NT) algorithm and 2) the enhanced NT algorithm, as well as the impact of roughness on the AMSR-E snow depth algorithm. Surface snow and ice data collected during the AMSR-Ice03 field campaign held in March 2003 near Barrow, AK, were used to force the radiative transfer model, and resultant modeled Tbs are compared with airborne passive microwave observations from the Polarimetric Scanning Radiometer. Results indicate that passive microwave Tbs are very sensitive even to small variations in incidence angle, which can cause either an over or underestimation of the true amount of sea ice in the pixel area viewed. For example, this paper showed that if the sea ice areas modeled in this paper mere assumed to be completely smooth, sea ice concentrations were underestimated by nearly 14% using the NT sea ice algorithm and by 7% using the enhanced NT algorithm. A comparison of polarization ratios (PRs) at 10.7,18.7, and 37 GHz indicates that each channel responds to different degrees of surface roughness and suggests that the PR at 10.7 GHz can be useful for identifying locations of heavily ridged or rubbled ice. Using the PR at 10.7 GHz to derive an "effective" viewing angle, which is used as a proxy for surface roughness, resulted in more accurate retrievals of sea ice concentration for both algorithms. The AMSR-E snow depth algorithm was found to be extremely sensitive to instrument calibration and sensor viewing angle, and it is concluded that more work is needed to investigate the sensitivity of the gradient ratio at 37 and

  14. Oil spreading in the deep sea and search for methods of discovering oil pollution under the sea surface

    NASA Astrophysics Data System (ADS)

    Goncharov, Vadim K.; Lyskov, Vladimir G.

    1994-10-01

    This report deals with the problem of estimation of the damages to the environment caused by the crude oil (or oil products) spills from underwater sources. The peculiarities of the oil movement caused by flotation and turbulence in the deep sea were considered on the basis of assumption that the oil dispersed on the separate drops. It is shown that the oil which is coming to the surface is divided into separate clusters in accordance with the sizes of the drops. Mathematical expressions were obtained that permitted us to evaluate the sizes of oil drops and clusters as well as oil concentration depending on time. The analysis of experimental data confirmed the theoretical results while using the diesel oil. Its drops had sizes from 0.10 to 1.34 mm. The diesel oil concentration in clusters corresponds to theoretical predictions.

  15. Seasonal and spatial heterogeneity of recent sea surface temperature trends in the Caribbean Sea and southeast Gulf of Mexico.

    PubMed

    Chollett, Iliana; Müller-Karger, Frank E; Heron, Scott F; Skirving, William; Mumby, Peter J

    2012-05-01

    Recent changes in ocean temperature have impacted marine ecosystem function globally. Nevertheless, the responses have depended upon the rate of change of temperature and the season when the changes occur, which are spatially variable. A rigorous statistical analysis of sea surface temperature observations over 25 years was used to examine spatial variability in overall and seasonal temperature trends within the wider Caribbean. The basin has experienced high spatial variability in rates of change of temperature. Most of the warming has been due to increases in summer rather than winter temperatures. However, warming was faster in winter in the Loop Current area and the south-eastern Caribbean, where the annual temperature ranges have contracted. Waters off Florida, Cuba and the Bahamas had a tendency towards cooling in winter, increasing the amplitude of annual temperature ranges. These detailed patterns can be used to elucidate ecological responses to climatic change in the region.

  16. No inter-gyre pathway for sea-surface temperature anomalies in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Foukal, Nicholas P.; Lozier, M. Susan

    2016-04-01

    Recent Lagrangian analyses of surface drifters have questioned the existence of a surface current connecting the Gulf Stream (GS) to the subpolar gyre (SPG) and have cast doubt on the mechanism underlying an apparent pathway for sea-surface temperature (SST) anomalies between the two regions. Here we use modelled Lagrangian trajectories to determine the fate of surface GS water and satellite SST data to analyse pathways of GS SST anomalies. Our results show that only a small fraction of the surface GS water reaches the SPG, the water that does so mainly travels below the surface mixed layer, and GS SST anomalies do not propagate into the SPG on interannual timescales. Instead, the inter-gyre heat transport as part of the Atlantic Meridional Overturning Circulation must be accomplished via subsurface pathways. We conclude that the SST in the SPG cannot be predicted by tracking SST anomalies along the GS.

  17. No inter-gyre pathway for sea-surface temperature anomalies in the North Atlantic

    PubMed Central

    Foukal, Nicholas P.; Lozier, M. Susan

    2016-01-01

    Recent Lagrangian analyses of surface drifters have questioned the existence of a surface current connecting the Gulf Stream (GS) to the subpolar gyre (SPG) and have cast doubt on the mechanism underlying an apparent pathway for sea-surface temperature (SST) anomalies between the two regions. Here we use modelled Lagrangian trajectories to determine the fate of surface GS water and satellite SST data to analyse pathways of GS SST anomalies. Our results show that only a small fraction of the surface GS water reaches the SPG, the water that does so mainly travels below the surface mixed layer, and GS SST anomalies do not propagate into the SPG on interannual timescales. Instead, the inter-gyre heat transport as part of the Atlantic Meridional Overturning Circulation must be accomplished via subsurface pathways. We conclude that the SST in the SPG cannot be predicted by tracking SST anomalies along the GS. PMID:27103496

  18. Surface connection between different areas in Mediterranean Sea derived from drifter data

    NASA Astrophysics Data System (ADS)

    Celentano, Paolo; Carlson, Daniel F.; Falco, Pierpaolo; Zambianchi, Enrico

    2016-04-01

    The surface connection of five study areas in the Mediterranean Sea (Sicily Strait, Gulf of Lyon, Ionian Sea, Alborán Sea and Crete Passage) is studied by looking at the statistical properties of near-surface lagrangian trajectories. The choice of the areas is due to the geographical distribution of data and the key role of these sub-basins in the dynamics of the Mediterranean. We used Lagrangian drifter data taken from the Mediterranean Surface Velocity Programme (http://nettuno.ogs.trieste.it/sire/medsvp/). The most common surface drifter used is the CODE-type drifter (Davis, 1985), designed to follow the vertical average velocity of the upper 1 m layer of the water column. The dataset consist of 1547 trajectories, deployed between 1986 and 2015 in all Mediterranean sub basins. By examining the drifter paths through the study areas, we computed transit and residence time, pseudo-Eulerian statistics and connection probabilities. Given the small number of drifters and the non-normal distribution of transit times, it is possible to use a bootstrap method (Efron and Tibshirani, 1986) to estimate the average transit time. In particular, we divided it into forward and backward transit times to consider the time taken by drifters respectively, from the exit of study area to end of its trajectory and from the deployment position to the study area. The main results indicate that the transit time between Sicily Strait and coast of Libya is about 83-103 days and between the Strait and the Gulf of Lyon is approximately 134 days. The time to reach the Adriatic Sea from the Ionian is around 30-40 days; the drifters take around 70 days to go from Alborán Sea to Sardinia channel and 43 days between Crete and the Ionian Sea. The Ionian Sea due has the highest number of drifter trajectories and the highest residence time, about 42 days. Also the Crete Passage has a high value of residence time, approximately 35 days; the other study areas are characterized by residence times of

  19. Sea-surface temperature gradients across blue whale and sea turtle foraging trajectories off the Baja California Peninsula, Mexico

    NASA Astrophysics Data System (ADS)

    Etnoyer, Peter; Canny, David; Mate, Bruce R.; Morgan, Lance E.; Ortega-Ortiz, Joel G.; Nichols, Wallace J.

    2006-02-01

    Sea-surface temperature (SST) fronts are integral to pelagic ecology in the North Pacific Ocean, so it is necessary to understand their character and distribution, and the way these features influence the behavior of endangered and highly migratory species. Here, telemetry data from sixteen satellite-tagged blue whales ( Balaenoptera musculus) and sea turtles ( Caretta caretta, Chelonia mydas, and Lepidochelys olivacea) are employed to characterize 'biologically relevant' SST fronts off Baja California Sur. High residence times are used to identify presumed foraging areas, and SST gradients are calculated across advanced very high resolution radiometer (AVHRR) images of these regions. The resulting values are compared to classic definitions of SST fronts in the oceanographic literature. We find subtle changes in surface temperature (between 0.01 and 0.10 °C/km) across the foraging trajectories, near the lowest end of the oceanographic scale (between 0.03 and 0.3 °C/km), suggesting that edge-detection algorithms using gradient thresholds >0.10 °C/km may overlook pelagic habitats in tropical waters. We use this information to sensitize our edge-detection algorithm, and to identify persistent concentrations of subtle SST fronts in the Northeast Pacific Ocean between 2002 and 2004. The lower-gradient threshold increases the number of fronts detected, revealing more potential habitats in different places than we find with a higher-gradient threshold. This is the expected result, but it confirms that pelagic habitat can be overlooked, and that the temperature gradient parameter is an important one.

  20. Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine

    NASA Astrophysics Data System (ADS)

    Carpenter, Lucy J.; MacDonald, Samantha M.; Shaw, Marvin D.; Kumar, Ravi; Saunders, Russell W.; Parthipan, Rajendran; Wilson, Julie; Plane, John M. C.

    2013-02-01

    Naturally occurring bromine- and iodine-containing compounds substantially reduce regional, and possibly even global, tropospheric ozone levels. As such, these halogen gases reduce the global warming effects of ozone in the troposphere, and its capacity to initiate the chemical removal of hydrocarbons such as methane. The majority of halogen-related surface ozone destruction is attributable to iodine chemistry. So far, organic iodine compounds have been assumed to serve as the main source of oceanic iodine emissions. However, known organic sources of atmospheric iodine cannot account for gas-phase iodine oxide concentrations in the lower troposphere over the tropical oceans. Here, we quantify gaseous emissions of inorganic iodine following the reaction of iodide with ozone in a series of laboratory experiments. We show that the reaction of iodide with ozone leads to the formation of both molecular iodine and hypoiodous acid. Using a kinetic box model of the sea surface layer and a one-dimensional model of the marine boundary layer, we show that the reaction of ozone with iodide on the sea surface could account for around 75% of observed iodine oxide levels over the tropical Atlantic Ocean. According to the sea surface model, hypoiodous acid--not previously considered as an oceanic source of iodine--is emitted at a rate ten-fold higher than that of molecular iodine under ambient conditions.

  1. Unpolarized infrared emissivity with shadow from anisotropic rough sea surfaces with non-Gaussian statistics.

    PubMed

    Bourlier, Christophe

    2005-07-10

    The emissivity of two-dimensional anisotropic rough sea surfaces with non-Gaussian statistics is investigated. The emissivity derivation is of importance for retrieval of the sea-surface temperature or equivalent temperature of a rough sea surface by infrared thermal imaging. The well-known Cox-Munk slope probability-density function, considered non-Gaussian, is used for the emissivity derivation, in which the skewness and the kurtosis (related to the third- and fourth-order statistics, respectively) are included. The shadowing effect, which is significant for grazing angles, is also taken into account. The geometric optics approximation is assumed to be valid, which means that the rough surface is modeled as a collection of facets reflecting locally the light in the specular direction. In addition, multiple reflections are ignored. Numerical results of the emissivity are presented for Gaussian and non-Gaussian statistics, for moderate wind speeds, for near-infrared wavelengths, for emission angles ranging from 0 degrees (nadir) to 90 degrees (horizon), and according to the wind direction. In addition, the emissivity is compared with both measurements and a Monte Carlo ray-tracing method.

  2. A sea surface salinity dipole mode in the tropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Zhang, Yuhong; Du, Yan; Qu, Tangdong

    2016-10-01

    Based on the 10 years sea surface salinity (SSS) data from Argo, we identified a salinity dipole mode in the tropical Indian Ocean, termed S-IOD: a pattern of interannual SSS variability with anomalously low-salinity in the central equatorial and high-salinity in the southeastern tropical Indian Ocean. The S-IOD matures in November-December, lagging the Indian Ocean dipole (IOD) mode derived from sea surface temperature (SST) by 2 months. For the period of observations, the S-IOD persists longer than the IOD, until the following September-October. Oscillations of the two S-IOD poles are governed by different processes. Ocean advection associated with equatorial current variability dominates the SSS anomalies of the northern pole, while surface freshwater flux variability plays a key role in the SSS anomalies of the southern pole, where anomalous precipitation is sustained by preformed sea surface temperature anomalies. The S-IOD concurs with the strong IOD, reflecting an ocean-atmosphere coupling through the SST-precipitation-SSS feedback.

  3. Unpolarized infrared emissivity with shadow from anisotropic rough sea surfaces with non-Gaussian statistics.

    PubMed

    Bourlier, Christophe

    2005-07-10

    The emissivity of two-dimensional anisotropic rough sea surfaces with non-Gaussian statistics is investigated. The emissivity derivation is of importance for retrieval of the sea-surface temperature or equivalent temperature of a rough sea surface by infrared thermal imaging. The well-known Cox-Munk slope probability-density function, considered non-Gaussian, is used for the emissivity derivation, in which the skewness and the kurtosis (related to the third- and fourth-order statistics, respectively) are included. The shadowing effect, which is significant for grazing angles, is also taken into account. The geometric optics approximation is assumed to be valid, which means that the rough surface is modeled as a collection of facets reflecting locally the light in the specular direction. In addition, multiple reflections are ignored. Numerical results of the emissivity are presented for Gaussian and non-Gaussian statistics, for moderate wind speeds, for near-infrared wavelengths, for emission angles ranging from 0 degrees (nadir) to 90 degrees (horizon), and according to the wind direction. In addition, the emissivity is compared with both measurements and a Monte Carlo ray-tracing method. PMID:16045222

  4. The Transient Circulation Response to Radiative Forcings and Sea Surface Warming

    SciTech Connect

    Staten, Paul; Reichler, Thomas; Lu, Jian

    2014-08-27

    Tropospheric circulation shifts have strong potential to impact surface climate. But the magnitude of these shifts in a changing climate, and the attending regional hydrological changes, are difficult to project. Part of this difficulty arises from our lack of understanding of the physical mechanisms behind the circulation shifts themselves. In order to better delineate circulation shifts and their respective causes, we decompose the circulation response into (1) the "direct" response to radiative forcings themselves, and (2) the "indirect" response to changing sea surface temperatures. Using ensembles of 90-day climate model simulations with immediate switch-on forcings, including perturbed greenhouse gas concentrations, stratospheric ozone concentrations, and sea surface temperatures, we document the direct and indirect transient responses of the zonal mean general circulation, and investigate the roles of previously proposed mechanisms in shifting the midlatitude jet. We find that both the direct and indirect wind responses often begin in the lower stratosphere. Changes in midlatitude eddies are ubiquitous and synchronous with the midlatitude zonal wind response. Shifts in the critical latitude of wave absorption on either flank of the jet are not indicted as primary factors for the poleward shifting jet, although we see some evidence for increasing equatorward wave reflection over the southern hemisphere in response to sea surface warming. Mechanisms for the northern hemisphere jet shift are less clear.

  5. Distribution of total mercury in surface sediments of the western Jade Bay, Lower Saxonian Wadden Sea, southern North Sea.

    PubMed

    Jin, Huafang; Liebezeit, Gerd; Ziehe, Daniel

    2012-04-01

    A total of 114 surface sediment samples was equidistantly collected in the western part of the Jade Bay, southern North Sea, to analyse total mercury contents as well as grain size distribution and total organic carbon (TOC) contents. Total mercury was determined by oxygen combustion-gold amalgamation. Validation, precision and accuracy of the method were evaluated and controlled with two certified reference materials (HISS-1 and MESS-3). Total mercury contents varied between 8 and 243 ng/g dry sediment with a mean value of 103 ng/g dw. The mercury levels in surface sediments showed an inhomogeneous spatial distribution with higher contents in near-dike areas. The values are mostly in the range of natural background values (50–100 ng/g dw) and positively related to TOC and clay/silt contents (<63 μm). The present total mercury contents are compared to those of previous studies, in order to estimate possible temporal trends of mercury contents in the study area over the last decades. Moreover, the comparison to sediment quality guidelines indicated that the surface sediments of the Jade Bay are not mercury contaminated. These results also suggested that the current mercury contents of Jade Bay surficial sediments are mostly affected by atmospheric deposition and re-emission.

  6. Sea surface density gradients in the Nordic Seas during the Holocene as revealed by paired microfossil and isotope proxies

    NASA Astrophysics Data System (ADS)

    Van Nieuwenhove, Nicolas; Hillaire-Marcel, Claude; Bauch, Henning A.; Vernal, Anne

    2016-03-01

    We attempt to assess the Holocene surface-subsurface seawater density gradient on millennial time scale based on the reconstruction of potential density (σθ) by combining data from dinoflagellate cyst assemblages and planktic foraminiferal (Neogloboquadrina pachyderma (s)) stable oxygen isotopes (δ18Oc). Following several calibration exercises, the likeliness of favorable seasonal preconditioning to open ocean convection is evaluated. The reconstructed σθ values reveal unfavorable conditions for vertical convection in the western Nordic Seas prior to ~7-6.5 ka B.P., with a westward increase and persistence of surface water buoyancy. Active overturning became more likely after 6.5 ka B.P. as suggested by a reduced and recurrently inverted vertical σθ gradient, while intermittent eastward spreading of lower density surface waters continued to modulate the area of potential overturning. Despite some reservation regarding the accuracy of the σθ values reconstructed, the documentation of relative changes of σθ gradients through time and space is suggested as a helpful tool for the appraisal of past overturning likeliness.

  7. Variability of sea ice melt and meteoric water input in the surface Labrador Current off Newfoundland

    NASA Astrophysics Data System (ADS)

    Benetti, M.; Reverdin, G.; Pierre, C.; Khatiwala, S.; Tournadre, B.; Olafsdottir, S.; Naamar, A.

    2016-04-01

    The respective contributions of saline (Atlantic and Pacific water) and freshwater (sea ice melt, meteoric water) components in the surface Labrador Current are quantified using salinity, δ18O, and nutrient data collected between 2012 and 2015 east of Newfoundland to investigate the seasonal variability of salinity in relation with the different freshwater contributions. Nutrient data indicate that the surface saline water is composed on average over 2012-2015 of roughly 62% Atlantic Water and 38% Pacific Water. A large salinity seasonal cycle of ≈ 1.5 peak-to-peak amplitude is found over the middle continental shelf, which is explained by the freshwater input seasonal variability: 2/3 of the amplitude of the salinity seasonal cycle can be explained by meteoric water input and 1/3 by the sea ice melt. A smaller seasonal salinity cycle (≈1.3) is observed over the inner shelf compared to the middle shelf, because of smaller variability in the large meteoric water inputs. Furthermore, the data reveal that sea ice melt (SIM) input was particularly important during July 2014, following a larger extension of sea ice over the Labrador shelf during the 2013/2014 winter season, compared to both previous winter seasons. Some patches of large SIM contribution observed during July 2014 and April 2015 were located on the continental slope or further offshore. The comparison of 2012-2015 data with data collected in 1994-1995 shows that the surface water over the Newfoundland shelf and slope is strongly affected by sea ice processes in both periods and suggests a larger contribution of brines over the slope during 1994-1995.

  8. The equatorial Atlantic sea surface temperature variability during the last millennium

    NASA Astrophysics Data System (ADS)

    Prado, Luciana; Wainer, Ilana; Khodri, Myriam

    2014-05-01

    The study of the variability patterns of the South Atlantic Basin is necessary to understand and predict the global climate because of its fundamental role in global climate control through heat transport to the North. As early as 330 years ago, the importance of the continental heat budget on the equatorial Atlantic Ocean driving the trade winds in the Gulf of Guinea was identified. However, only five decades ago studies started to understand the effects of these air-sea interaction processes over the Atlantic sector. More specifically, changes in continental rainfall are linked to the interannual variability of the equatorial Atlantic sea surface temperature, which is related to the Atlantic Niño. Here we aim to examine air-sea interaction processes in the tropical Atlantic region during key periods within the Last Millennium (LM, 850 to 1,850 Common Era, C.E.). This will be achieved by computing an index to the variability of the equatorial Atlantic sea surface temperature during the LM. This variability pattern will be obtained from the National Center for Atmospheric Research - Community Climate System Model, version 4 (NCAR-CCSM4.0) and the Institut Pierre Simon Laplace - Climate Model version 5A, low resolution (IP