230 Th normalization: new insights on an essential tool for quantifying sedimentary fluxes in the modern and quaternary ocean

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Costa, K. M., Hayes, C. T., Anderson, R. F., Pavia, F. J., Bausch, A., Deng, F., Dutay, J., Geibert, W., Heinze, C., Henderson, G., Hillaire-Marcel, C., Hoffmann, S., Jaccard, S. L., Jacobel, A. W., Kienast, S. S., Kipp, L., Lerner, P., Lippold, J., Lund, D., Marcantonio, F., McGee, D., McManus, J. F., Mekik, F., Middleton, J. L., Missiaen, L., Not, C., Pichat, S., Robinson, L. F., Rowland, G. H., Roy-Barman, M., Alessandro, Torfstein, A., Winckler, G., & Zhou, Y. 230 Th normalization: new insights on an essential tool for quantifying sedimentary fluxes in the modern and quaternary ocean. Paleoceanography and Paleoclimatology, 35(2), (2020): e2019PA003820, doi:10.1029/2019PA003820.230Th normalization is a valuable paleoceanographic tool for reconstructing high‐resolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more diverse marine environments, the nuances of 230Th systematics, with regard to particle type, particle size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records of 230Th from across the global ocean at two time slices, the late Holocene (0–5,000 years ago, or 0–5 ka) and the Last Glacial Maximum (18.5–23.5 ka), and investigated the spatial structure of 230Th‐normalized mass fluxes. On a global scale, sedimentary mass fluxes were significantly higher during the Last Glacial Maximum (1.79–2.17 g/cm2kyr, 95% confidence) relative to the Holocene (1.48–1.68 g/cm2kyr, 95% confidence). We then examined the potential confounding influences of boundary scavenging, nepheloid layers, hydrothermal scavenging, size‐dependent sediment fractionation, and carbonate dissolution on the efficacy of 230Th as a constant flux proxy. Anomalous 230Th behavior is sometimes observed proximal to hydrothermal ridges and in continental margins where high particle fluxes and steep continental slopes can lead to the combined effects of boundary scavenging and nepheloid interference. Notwithstanding these limitations, we found that 230Th normalization is a robust tool for determining sediment mass accumulation rates in the majority of pelagic marine settings (>1,000 m water depth).We thank Zanna Chase and one anonymous reviewer for valuable feedback. K. M. C. was supported by a Postdoctoral Scholarship at WHOI. L. M. acknowledges funding from the Australian Research Council grant DP180100048. The contribution of C. T. H., J. F. M., and R. F. A. were supported in part by the U.S. National Science Foundation (US‐NSF). G. H. R. was supported by the Natural Environment Research Council (grant NE/L002434/1). S. L. J. acknowledges support from the Swiss National Science Foundation (grants PP002P2_144811 and PP00P2_172915). This study was supported by the Past Global Changes (PAGES) project, which in turn received support from the Swiss Academy of Sciences and the US‐NSF. This work grew out of a 2018 workshop in Aix‐Marseille, France, funded by PAGES, GEOTRACES, SCOR, US‐NSF, Aix‐Marseille Université, and John Cantle Scientific. All data are publicly available as supporting information to this document and on the National Center for Environmental Information (NCEI) at https://www.ncdc.noaa.gov/paleo/study/28791

Global Ocean Sediment Composition and Burial Flux in the Deep Sea

Quantitative knowledge about the burial of sedimentary components at the seafloor has wide-ranging implications in ocean science, from global climate to continental weathering. The use of 230Th-normalized fluxes reduces uncertainties that many prior studies faced by accounting for the effects of sediment redistribution by bottom currents and minimizing the impact of age model uncertainty. Here we employ a recently compiled global data set of 230Th-normalized fluxes with an updated database of seafloor surface sediment composition to derive atlases of the deep-sea burial flux of calcium carbonate, biogenic opal, total organic carbon (TOC), nonbiogenic material, iron, mercury, and excess barium (Baxs). The spatial patterns of major component burial are mainly consistent with prior work, but the new quantitative estimates allow evaluations of deep-sea budgets. Our integrated deep-sea burial fluxes are 136 Tg C/yr CaCO3, 153 Tg Si/yr opal, 20Tg C/yr TOC, 220 Mg Hg/yr, and 2.6 Tg Baxs/yr. This opal flux is roughly a factor of 2 increase over previous estimates, with important implications for the global Si cycle. Sedimentary Fe fluxes reflect a mixture of sources including lithogenic material, hydrothermal inputs and authigenic phases. The fluxes of some commonly used paleo-productivity proxies (TOC, biogenic opal, and Baxs) are not well-correlated geographically with satellite-based productivity estimates. Our new compilation of sedimentary fluxes provides detailed regional and global information, which will help refine the understanding of sediment preservation

Investigation on accuracies of real time kinematic GPS for GIS applications

Since the advent of Geographic Information Systems (GIS) people specialised in this area or connected with GIS at an administrative or user level have been looking for economical and productive means to accomplish data acquisition tasks. Because the data acquisition constitutes a major part of any GIS, the scientific community, especially geodetic surveyors, have come up with the real time kinematic (RTK) GPS solution. This paper investigates the performance (internal and external accuracy) of RTK GPS. For this purpose, two separate tests are conducted. In the first test, three cases are taken in consideration for internal accuracy, namely, identical satellite configuration, different satellite configuration and different reference station. In the second test, two cases are examined in which RTK GPS results are compared with the static GPS and conventional terrestrial methods. The results from all the tests have proved that this modern technique is very suitable for data acquisition of GISs as well as efficient and economical. © 2009 by the authors

Multipath effects in RTK GPS and a case study

Contemporary projects requiring real time positions with especially cm accuracies have begun to employ Real Time Kinematic GPS (RTK GPS) technique for its speedy and productive nature. As in all types of GPS techniques, RTK GPS is also vulnerable to multipath errors. The purpose of this study is to investigate this source of error. This study tries to answer some questions such as how much multipath error causes real time positioning error, and in what kind of environment this error is the most effective. A background on multipath error is first given and the environment causing this effect is widely researched, and then a test that brings out the most multipath error is conducted. The findings are presented, and conclusions and suggestions are included for future researches

An investigation on multipath errors in real time kinematic GPS method

Today real time kinematic GPS (RTK GPS) is the newest and the most common method utilized in tasks requiring real time positions with especially, centimeter accuracies. However, as with all good things in life, this contemporary method of positioning is not flawless, that is, not free from errors. As in static GPS, RTK GPS is also susceptible to multipath errors. This study aims to investigate this source of error and attempts to answers some questions such as how much multipath error causes real time positioning error, in what kind of environment this error is the most effective and how large the positional errors this multipath produces. For these reasons, the fundamental background on multipath error was first covered and the surrounding causing this effect was widely researched, hence a test environment was designed. Various analyses were conducted in light of the findings obtained from the tests carried out and conclusions and suggestions were made in detailed fashion so that they could lead the way to future researches. © 2010 Academic Journals

Modelling and validation of the weighted mean temperature for Turkey

Water vapour is involved in many atmospheric processes. Precipitation specifically relies on the amount of precipitable water vapour (PWV) or the water vapour content suspended in the atmosphere. Opportunities with regard to the conversion of existing continuous Global Navigation Satellite System (GNSS) stations to GNSS meteorology stations (GNSS MET) with very little cost and acquisition of near real-time water vapour have become popular in studies of the estimation of water vapour using GNSSs. In order to convert the GNSS observables into meteorological assets, one has to account for the extremely important conversion parameters between zenith wet delay and PWV in GNSS meteorology: Tm or Q. They are estimated by analysis of radiosonde profile observations of a radiosonde station (RS). In this study, linear Tm models were estimated from 4103 profile observations of eight Turkish RSs for the year 2011. The verification of these models was tested by using 1 year of observations at the Ankara and Istanbul RS-GNSS stations. A Tm = 48.55 + 0.80Ts model was computed for Turkey with a root mean square error of ±2.57 K. The accuracies of PWV derived from the developed Tm model and the GNSS observations at the Ankara and Istanbul stations in 2013 and 2014 were found to be ±1.7 and ±1.8 mm, respectively. © 2016 Royal Meteorological Society112Y350 National Council for Scientific ResearchThis study is funded by the Scientific and Technological Research Council of Turkey (TUBITAK) for the project entitled ?The Estimation of Atmospheric Water Vapour with GPS? (Project No: 112Y350). Res. Asst. Gokhan Gurbuz is thanked for helping us with GNSS processing

The Turkish real time kinematic GPS network (TUSAGA-Aktif) infrastructure

The concept of Real Time Kinematic (RTK) Network has become popular throughout the world since the beginning of 2000s. The RTK Network server collects satellite observations from the RTK Network, performs calculations and sends RTK corrections to the rover. Thus, these RTK Networks eliminates the need for post-processing GPS observations; instead the users in the field instantaneously obtain the receiver antenna's three dimensional coordinates with cm accuracy. This paper details the infrastructure of the Turkish RTK CORS Network called TUSAGA-Aktif established by Istanbul Kultur University in association with the General Directorate of Land Registration and Cadastre and the general command of mapping and sponsored by the Turkish Scientific and Technical Research Agency (TUBITAK). The network constitutes 146 Continuously Operating Reference Stations controlled by the two control stations, the Master Control Station at the Photogrammetry and Geodesy Administration of the general directorate of land registration and cadastre and the auxiliary control station at the headquarters of the general command of mapping both in Ankara, the capital city of Turkey. © 2011 Academic Journals

Review of variations in Mw<7 earthquake motions on position and TEC (Mw Combining double low line 6.5 Aegean Sea earthquake sample)

Turkey is a country located in the middle latitude zone, where tectonic activity is intensive. Recently, an earthquake of magnitude 6.5 Mw occurred offshore in the Aegean Sea on 24 May 2014 at 09:25 UTC, which lasted about 40 s. The earthquake was also felt in Greece, Romania, and Bulgaria in addition to Turkey. In recent years, ionospheric anomaly detection studies have been carried out because of seismicity with total electron content (TEC) computed from the global navigation satellite system's (GNSS) signal delays and several interesting findings have been published. In this study, both TEC and positional variations have been examined separately following a moderate size earthquake in the Aegean Sea. The correlation of the aforementioned ionospheric variation with the positional variation has also been investigated. For this purpose, a total of 15 stations was used, including four continuously operating reference stations in Turkey (CORS-TR) and stations in the seismic zone (AYVL, CANA, IPSA, and YENC), as well as international GNSS service (IGS) and European reference frame permanent network (EPN) stations. The ionospheric and positional variations of the AYVL, CANA, IPSA, and YENC stations were examined using Bernese v5.0 software. When the precise point positioning TEC (PPP-TEC) values were examined, it was observed that the TEC values were approximately 4 TECU (total electron content unit) above the upper-limit TEC value at four stations located in Turkey, 3 days before the earthquake at 08:00 and 10:00 UTC. At the same stations, on the day before the earthquake at 06:00, 08:00, and 10:00 UTC, the TEC values were approximately 5 TECU below the lower-limit TEC value. The global ionosphere model TEC (GIM-TEC) values published by the Centre for Orbit Determination in Europe (CODE) were also examined. Three days before the earthquake, at all stations, it was observed that the TEC values in the time period between 08:00 and 10:00 UTC were approximately 2 TECU above the upper-limit TEC value; 1 day before the earthquake at 06:00, 08:00, and 10:00 UTC, the TEC values were approximately 4 TECU below the lower-limit TEC value. Again, by using the same 15 stations, positional variation investigation for before and after the earthquake was undertaken for the AYVL, CANA, IPSA, and YENC stations. As a result of the conducted analysis, positional displacements were seen before and after the earthquake at the CANA station, which is the nearest station to the earthquake centre. Before and after the earthquake, positional displacements were observed as 10 and 3 cm respectively. © 2016 Author(s)

MONITORING IONOSPHERIC VARIATION FOR A DEFINITE PERIOD TIME IN TURKEY

International Conference on Sensors and Models in Remote Sensing and Photogrammetry -- NOV 23-25, 2015 -- Kish Island, IRANWOS: 000380618200060Ionosphere has been studied by a number of scientists in recent years. Since GPS observations cannot provide TEC value directly, it can be estimated from combination of observations. In this study TEC values derived from GPS observations were produced variations with two hours increments from the eighth day to fifteenth day in months just after beginning of each season, namely January, April, July and October in 2014 for ZONG TUSAGA-Aktif station and 41 other stations (TUSAGA-Aktif, EUREF, IGS). TEC values computed by the Bernese 5.0 software were compared with the Global Ionosphere Model (GIM) TEC values regularly published by Center for Orbit Determination in Europe (CODE) and International Reference Ionosphere (IRI-2012) TEC values. As a result of this study, with the comparison of GPS TEC values to GIM TEC values, it has become obvious that GPS TEC values are quite similar to the GIM TEC values. The differences of TEC values derived from GPS TEC and GIM TEC change from 0.91 TECU (January) to 1.88 TECU (October). On the other hand, GPS TEC values are also compared with IRI TEC values, and found out that there is a considerable difference between the two TEC values ranging from 6.30 TECU (January) to 15.15 TECU (April). Moreover, TEC values derived from GPS measurements are attained similar to GIM TEC, but found to stray from IRI-2012 TEC values remarkably

Effects of ocean tide models on GNSS-estimated ZTD and PWV in Turkey

ISPRS International Conference on Sensors and Models in Remote Sensing and Photogrammetry 2015 -- 23 November 2015 through 25 November 2015 -- -- 121731Global Navigation Satellite System (GNSS) observations can precisely estimate the total zenith tropospheric delay (ZTD) and precipitable water vapour (PWV) for weather prediction and atmospheric research as a continuous and all-weather technique. However, apart from GNSS technique itself, estimations of ZTD and PWV are subject to effects of geophysical models with large uncertainties, particularly imprecise ocean tide models in Turkey. In this paper, GNSS data from Jan. 1st to Dec. 31st of 2014 are processed at 4 co-located GNSS stations (GISM, DIYB, GANM, and ADAN) with radiosonde from Turkish Met-Office along with several nearby IGS stations. The GAMIT/GLOBK software has been used to process GNSS data of 30-second sample using the Vienna Mapping Function and 10° elevation cut-off angle. Also tidal and non-tidal atmospheric pressure loadings (ATML) at the observation level are also applied in GAMIT/GLOBK. Several widely used ocean tide models are used to evaluate their effects on GNSS-estimated ZTD and PWV estimation, such as IERS recommended FES2004, NAO99b from a barotropic hydrodynamic model, CSR4.0 obtained from TOPEX/Poseidon altimetry with the model FES94.1 as the reference model and GOT00 which is again long wavelength adjustments of FES94.1 using TOPEX/Poseidon data at 0.5 by 0.5 degree grid. The ZTD and PWV computed from radiosonde profile observations are regarded as reference values for the comparison and validation. In the processing phase, five different strategies are taken without ocean tide model and with four aforementioned ocean tide models, respectively, which are used to evaluate ocean tide models effects on GNSS-estimated ZTD and PWV estimation through comparing with co-located Radiosonde. Results showed that ocean tide models have greatly affected the estimation of the ZTD in centimeter level and thus the precipitable water vapour in millimeter level, respectively at stations near coasts. The ocean tide model FES2004 that is the product of assimilation of the altimetric data of ERS2, TOPEX/POSEIDON and the data of a global tide gauge network, gave the most accurate results when compared to radiosonde with ±1.99 mm in PWV at stations near coastline. While other ocean tides models agree each other at millimeter level in PWV. However, at inland GNSS stations, ocean tide models have less effects on GNSS-estimated ZTD and PWV, e.g., with ±1.0 mm in ZTD and ±0.1 mm in PWV