Autosub6000:A Deep Diving Long Range AUV

With an ultimate range up to 1000 km,a maximum operating depth of 6000 m,and a generous payload capacity,Autosub6000 is well placed to become one of the world's most capable deep diving Autonomous Underwater Vehicles(AUVs). Recently,Autosub6000 successfully completed its first deep water engineering trials,and in September 2008,fitted with a multibeam sonar,will carry out its first science missions.This paper will describe how we are tackling the design issues that specifically affect a deep diving AUV which must be capable of operating with true autonomy,independently of the mother ship, namely:carrying adequate energy for long endurance and range,coping with varying buoyancy,and maintaining accurate navigation throughout missions lasting up to several days.Results from the recent engineering trails are presented,and future missions and development plans are discussed.

Theoretical design and dynamic simulation of new mining paths of tracked miner on deep seafloor

With comprehensive considerations of the operational safety and collection efficiency for the tracked miner collecting the seafloor poly-metallic nodules, two new improved mining paths for the miner on the deep seafloor were proposed. Compared to the conventional mining path, the design principles and superiorities of the two new paths are that the miner turning with relative long radius should avoid large sinkage and high slip, so as to ensure its operational safety, while the space between its straight-line trajectories before and after the turning is optimum, which is designed as the total width of the miner, and collect nodules as more as possible, so as to ensure its collection efficiency. To realize the new mining paths, theoretical designs and quantitative calculations were carried out to determine the exact positions for the speed controls of the miner during its whole operation process. With the new dynamic model of the miner, and through regulations of the speeds of the left and right tracks of the miner on the exact motion positions according to the theoretical calculations, the two new improved mining paths for the miner on the seafloor were successfully simulated, thus the turning radius of the miner in the simulation is about 21.8 m, while the distance between the straight-line trajectories before and after the turning is about 5.2 m. The dynamic simulation results preliminarily prove the feasibility of these two new mining paths, and further can provide important theoretical guidance and useful technical reference for the practical tracked miner operation and control on the seafloor.

Feasibility investigation on deep ocean compact autonomous Raman spectrometer developed for in-situ detection of acid radical ions

A newly developed Deep Ocean Compact Autonomous Raman Spectrometer （DOCARS） system is introduced and used for in-situ detection of acid radical ions in this paper. To evaluate the feasibility and capability of DOCARS for quantitative analysis of the acid radical ions in the deep ocean, extensive investigations have been carried out both in laboratory and sea trials during the development phase. In the laboratory investigations, Raman spectra of the prepared samples （acid radical ions solutions） were obtained, and analyzed using the method of internal standard normalization in data processing. The Raman signal of acid radical ions was normalized by that of water molecules. The calibration curve showed that the normalized Raman signal intensity of SO4^2-, NO3^-, and HCO^-3 increases linearly as the concentration rises with correlation coefficient R^2 of 0.99, 0.99, and 0.98 respectively. The linear function obtained from the calibration curve was then used for the analysis of the spectra ,data acquired in the sea trial under a simulating chemical field in the deep-sea environment. It was found that the detected concentration of NO3 according to the linear function can reflect the concentration changes of NO~ after the sample was released, and the detection accuracy of the DOCARS system for SO^2-_4 is 8%. All the results showed that the DOCARS system has great potential in quantitative detection of acid radical ions under the deep-sea environment, while the sensitivity of the DOCARS system is expected to be improved.

Development of A Deep Ocean Electric Autonomous Manipulator

This paper describes an underwater 3500 m electric manipulator （named Huahai-4E, stands for four functions deep ocean electric manipulator in China）, which has been developed at underwater manipulation technology lab in Huazhong University of Science and Technology （HUST） for a test bed of studying of deep ocean manipulation technologies. The manipulator features modular integration joints, and layered architecture control system. The oil-filled, pressure-compensated joint is compactly designed and integrated of a permanent magnet （PM） brushless motor, a drive circuit, a harmonic gear and an angular feedback potentiometer. The underwater control system is based on a network and consisted of three embedded PC/104 computers which are used for servo control, task plan and target sensor respectively. They communicate through User Datagram Protocol （UDP） multicast communication in Vxworks OS. A supervisor PC with a virtual 3D GUI is fiber linked to underwater control system. Furthermore, the manipulator is equipped with a sensor system including a unique ultra-sonic probe array and an underwater camera. Autonomous grasp strategy based multi-sensor is studied. The results of watertight test in 40 MPa, joint＇s efficiency test and autonomous grasp experiments in tank are also presented.

A Simple Method for Source Depth Estimation with Multi-path Time Delay in Deep Ocean

A method of source depth estimation based on the multi-path time delay difference is proposed. When the minimum time arrivals in all receiver depths are snapped to a certain time on time delay-depth plane, time delay arrivals of surface-bottom reflection and bottom-surface reflection intersect at the source depth. Two hydrophones deployed vertically with a certain interval are required at least. If the receiver depths are known, the pair of time delays can be used to estimate the source depth. With the proposed method the source depth can be estimated successfully in a moderate range in the deep ocean without complicated matched-field calculations in the simulations and experiments.

Detecting Regional Deep Ocean Warming below 2000 Meter Based on Altimetry,GRACE,Argo,and CTD Data

The deep ocean below 2000 m is a large water body with the sparsest data coverage,challenging the closure of the sea-level budget and the estimation of the Earth’s energy imbalance.Whether the deep ocean below 2000 m is warming globally has been debated in the recent decade.However,as the regional signals are generally larger than the global average,it is intriguing to investigate the regional temperature changes.Here,we adopt an indirect method that combines altimetry,GRACE,and Argo data to examine the global and regional deep ocean temperature changes below 2000 m.The consistency between high-quality conductivity-temperature-depth(CTD)data from repeated hydrographic sections and our results confirms the validity of the indirect method.We find that the deep oceans are warming in the Middle East Indian Ocean,the subtropical North and Southwest Pacific,and the Northeast Atlantic,but cooling in the Northwest Atlantic and Southern oceans from 2005 to 2015.

Clean and Safe Supply of Fish and Shellfish to Clear the HACCP Regulation by Use of Clean and Cold Deep Ocean Water in Rausu,Hokkaido,Japan

For the supply of fish and shellfish to consumers in fresh condition, clean handling after catch from the sea is essential. According to HACCP （Hazard Analysis and Critical Control Points）, it is important to meet such requirement by keeping fish and shellfish under a certain low temperature and clean conditions after catching. The deep ocean water （DOW） characterized by low temperature and cleanliness has been chosen for fish and shellfish handlings, particularly for salmon, cod, and sea urchin in Town ＇Rausu＇ in Hokkaido, Japan. DOW below 2.9℃ of an amount of nearly 5 000 m^3 is planned to be pumped up every day from a depth of about 350 m, and temporarily stored in a large simulated tank on land. DOW is then supplied to fish boats through hydrants distributed throughout the harbor and used for keeping salmon in clean and cold conditions. Ice made from DOW is also used for lowering temperature if necessary. DOW and ice made from DOW are also used during the transportation of fish and shellfish. The entire system is scheduled to be completed by the summer of 2005.

Geoacoustic Inversion for Bottom Parameters via Bayesian Theory in Deep Ocean

We develop a new approach to estimating bottom parameters based on the Bayesian theory in deep ocean. The solution in a Bayesian inversion is characterized by its posterior probability density （PPD）, which combines prior information about the model with information from an observed data set. Bottom parameters are sensitive to the transmission loss （TL） data in shadow zones of deep ocean. In this study, TLs of different frequencies from the South China Sea in the summer of 2014 are used as the observed data sets. The interpretation of the multidimensional PPD requires the calculation of its moments, such as the mean, covariance, and marginal distributions, which provide parameter estimates and uncertainties. Considering that the sensitivities of shallow- zone TLs vary for different frequencies of the bottom parameters in the deep ocean, this research obtains bottom parameters at varying frequencies. Then, the inversion results are compared with the sampling data and the correlations between bottom parameters are determined. Furthermore, we show the inversion results for multi- frequency combined inversion. The inversion results are verified by the experimental TLs and the numerical results, which are calculated using the inverted bottom parameters for different source depths and receiver depths at the corresponding frequency.

Numerical Simulation of Installation Process and Uplift Resistance for An Integrated Suction Foundation in Deep Ocean

A concept design, named integrated suction foundation, is proposed for a tension leg platform（TLP） in deep ocean. The most important improvement in comparing with the traditional one is that a pressure-resistant storage module is designed. It utilizes the high hydrostatic pressure in deep ocean to drive water into the module to generate negative pressure for bucket suction. This work aims to further approve the feasibility of the concept design in the aspect of penetration installation and the uplift force in-place. Seepage is generated during suction penetration, and can have both positive and negative effects on penetration process. To study the effect of seepage on the penetration process of the integrated suction foundation, finite element analysis（FEA） is carried out in this work. In particular, an improved methodology to calculate the penetration resistance is proposed for the integrated suction foundation with respect to the reduction factor of penetration resistance. The maximum allowable negative pressure during suction penetration is calculated with the critical hydraulic gradient method through FEA. The simulation results of the penetration process show that the integrated suction foundation can be installed safely. Moreover, the uplift resistance of the integrated suction foundation is calculated and the feasibility of the integrated suction foundation working on-site is verified. In all, the analysis in this work further approves the feasibility of the integrated suction foundation for TLPs in deep ocean applications.

Proof of Six-Wave Resonance Conditions of Ocean Surface Gravity Waves in Deep Water

A necessary big step up in the modern water wave theories and their widespread application in ocean engineering is how to obtain 6-wave resonance conditions and to prove it. In the light of the existing forms and characteristics of 3-wave, 4-wave and 5-wave resonance conditions, the 6-wave resonance conditions are proposed and proved for currently a maximum wave-wave resonance interactions of the ocean surface gravity waves in deep water, which will be indispensable to both the Kolmogorov spectrum of the corresponding universal wave turbulence and a synthetic 4-5-6-wave resonant model for the ocean surface gravity waves.

Abyssal Circulation in the Philippine Sea

The abyssal circulation in the Philippine Sea(PS)is investigated,with outputs from the Simple Ocean Data Assimilation version 2.2.4(SODA224).The deep-water currents in SODA224 are carefully evaluated,with sparse in situ observations in the North Pacific Ocean.In the upper deep layer(20003000 m)of the PS,a strong westward current,which originates from the Northeast Pacific Basin and enters the PS through the Yap-Mariana Junction,exists along 1114 N.This strong westward current bifurcates into two western boundary currents off the Philippines.The northward-flowing current flows out of the PS around 2021 N,whereas the southward-flowing current transports deep water from the northern hemisphere to the southern hemisphere.In the lower deep layer(30004500 m),the inflow water first flows northward to the east of the Western Mariana Basin and then turns westward at approximately 18 N.The inflow water mainly enters the Philippine Basin(PB),with a small part turning southward to constitute a weak cyclonic circulation.The water entering the PB mainly merges into a strong southward western boundary current in the south-ern PB.In the bottom layer(below 4500 m),both the northeast and northwest PB show single cyclonic gyres,whereas the south PB shows a single anticyclonic gyre.Moreover,comparisons with the observations indicate the possible existence of a cyclonic sense of circulation over the Philippine Trench.The current study provides the implications for future observations,which are needed to fur-ther investigate the temporospatial variations of the abyssal circulation in the PS on multiple scales.

An Integrated Dynamic Model of Ocean Mining System and Fast Simulation of Its Longitudinal Reciprocating Motion

An integrated dynamic model of China＇s deep ocean mining system is developed and the fast simulation analysis of its longitudinal reciprocating motion operation processes is achieved. The seafloor tracked miner is built as a three-dimensional single-body model with six-degree-of-freedom. The track-terrain interaction is modeled by partitioning the track-terrain interface into a certain number of mesh elements with three mutually perpendicular forces, including the normal force, the longitudinal shear force and the lateral shear force, acting on the center point of each mesh element. The hydrodynamic force of the miner is considered and applied. By considering the operational safety and collection efficiency, two new mining paths for the miner on the seafloor are proposed, which can be simulated with the established single-body dynamic model of the miner. The pipeline subsystem is built as a three-dimensional multi-body discrete element model, which is divided into rigid elements linked by flexible connectors. The flexible connector without mass is represented by six spring-damper elements. The external hydrodynamic forces of the ocean current from the longitudinal and lateral directions are both considered and modeled based on the Morison formula and applied to the mass center of each corresponding discrete rigid element. The mining ship is simplified and represented by a general kinematic point, whose heave motion induced by the ocean waves and the longitudinal and lateral towing motions are considered and applied. By integrating the single-body dynamic model of the miner and the multi-body discrete element dynamic model of the pipeline, and defining the kinematic equations of the mining ship, the integrated dynamic model of the total deep ocean mining system is formed. The longitudinal reciprocating motion operation modes of the total mining system, which combine the active straight-line and turning motions of the miner and the ship, and the passive towed motions of the pipeline, are proposed and simulated with the developed 3D dynamic model. Some critical simulation results are obtained and analyzed, such as the motion trajectories of key subsystems, the velocities of the buoyancy modules and the interaction forces between subsystems, which in a way can provide important theoretical basis and useful technical reference for the practical deep ocean mining system analysis, operation and control.

Dinophysoid dinoflagellates from subphotic depths:Amphisolenia sp.aff.brevicauda,Dinofurcula tricornuta sp.nov.,and Dinophysis profunda sp.nov.(Dinophysales,Dinophyceae)

Three species of dinophysoid planktonic dinoflagellates are described from the eastern Mediterranean Sea.Amphisolenia sp.aff.brevicauda was collected at 70-m depth in the Ionian Sea.This small species showed a more asymmetric midbody and a proportionally longer neck when compared to the closer relative A.brevicauda.Three individuals of Dinofurcula tricornuta sp.nov.collected at 154-m depth in the Marmara Sea are characterized by three posterior-oriented processes when compared to its congeneric species.This is the first record of the genus Dinofurcula beyond the eastern tropical Pacific Ocean.Dinophysis profunda sp.nov.collected at 500-m depth in the Ionian Sea is characterized by ovate hypotheca and a serrate crest-like left sulcal list when compared to its close relative D.alata.These findings evidence an undescribed biodiversity in the under-sampled subphotic depths.

Statistics of underwater ambient noise at high sea states arisen from typhoon out zones in the Philippine Sea and South China Sea

Oceanic noise is the background interference in sonar performance prediction and evaluation at high sea states.Statistics of underwater ambient noise during Typhoons Soulik and Nida were analyzed on the basis of experimental measurements conducted in a deep area of the Philippine Sea and the South China Sea.Generated linear regression,frequency correlation matrix(FCM),Burr distribution and Gumbel distribution were described for the analysis of correlation with environmental parameters including wind speed(WS),significant wave height(SWH),and the inter-frequency relationship and probability density function of noise levels(NLs).When the typhoons were quite close to the receivers,the increment of NLs exceeded 10 dB.Whilst ambient noise was completely dominated by wind agitation,NLs were proportional to the cubic and quintic functions of WS and SWH,respectively.The fitted results between NLs and oceanic parameters were different for“before typhoon”and“after typhoon”.The fitted slopes of linear regression showed a linear relationship with the logarithm of frequency.The average observed typhoon-generated NLs were 5 dB lower than the Wenz curve at the same wind force due to the insufficiently developed sea state or the delay between NLs and WS.The cross-correlation coefficient of FCM,which can be utilized in the identification of noise sources in different bands,exceeded 0.8 at frequencies higher than 250 Hz.Furthermore,standard deviation increased with frequency.The kurtosis was equal to 3 at>400 Hz approximately.The characteristics of NLs showed good agreement with the results of FCM.

Productivity in the Southern Ocean Antarctic Zone during the Northern Hemisphere Glaciation(NHG)and its link to atmospheric pCO_(2)

A decrease in atmospheric CO_(2)partial pressure(pCO_(2))is considered an important prerequisite for the onset and intensification of Northern Hemisphere Glaciation(NHG).However,how the ocean sequestered missing CO_(2)during the NHG is still uncertain.Changes in surface productivity and deep ventilation in the Southern Ocean(SO)have been proposed to explain the variations in atmospheric pCO_(2)over the last eight glacial cycles,but it is unclear whether these mechanisms contributed to the decrease in atmospheric pCO_(2)during the NHG.Using titanium-normalized contents and mass accumulation rates of biogenic opal and total organic carbon from the International Ocean Discovery Program(IODP)Expedition 374 Site U1524A,we reconstruct the productivity in the Ross Sea,Antarctica,from 3.3 Ma to 2.4 Ma.The productivity records exhibit a long-term decreasing trend and several distinct phased evolutionary features.Specifically,the local productivity fluctuated dramatically during 3.3-3.0 Ma,decreased gradually during 3.0-2.6 Ma,and remained relatively constant during 2.6-2.4 Ma.By comparing productivity with its potential influences,we infer that the phased and long-term evolutions of productivity were mainly controlled by changes in deep ocean ventilation.Sea ice expansion might have decreased productivity during 3.3-3.0 Ma by light attenuation.Changes in eolian dust input have little effect on productivity.Further analysis revealed no coupling linkage between productivity and atmospheric pCO_(2),indicating that the productivity in the SO Antarctic Zone(AZ)was not the main factor controlling the atmospheric CO_(2)decrease during the NHG.To improve our understanding of the role of SO processes in the NHG,further studies should focus on the potential influences of deep ocean ventilation on atmospheric pCO_(2)in the AZ,and similar studies should also be extended to the sea area in the Subantarctic Zone.

Solution to Long-Range Continuous and Precise Positioning in Deep Ocean for Autonomous Underwater Vehicles Using Acoustic Range Estimation and Inertial Sensor Measurements

Although advances in research into autonomous underwater vehicles(AUVs)have been made to extend their working depth and endurance,underwater experiments and missions remain to be restricted by the positioning performance of AUVs.With the Global Navigation Satellite System(GNSS)precluded due to the rapid attenuation of radio signals in underwater environments,acoustic positioning methods serve as an effective substitution.A long-range continuous and precise positioning solution for AUVs in deep ocean is proposed in this study,relying on acoustic signals from beacons at the same depth and aided by onboard inertial sensors.A signal system is investigated to provide time of arrival(TOA)estimation in a resolution of milliseconds.Without pre-knowledge or local measurement of the accurate sound speed,an AUV is enabled to continuously locate its horizontal position based on rough ranges estimated by an iterative least square(ILS)based algorithm.For better accuracy and robustness,range deviations are compensated with a reference point of known position and outliers in the trajectory are eliminated by an implementation of the extended Kalman filter(EKF)coupled with the state-acceptance filter.The solution is evaluated in simulation experiments with environmental information measured on the spot,providing an average position error from ground truth below 10 m with a standard deviation below 5 m.

The Deep Blue VC Ocean

Hugo Shong explains what it takes to be a successful venture capitalist Hugo Shong, Vice Chairman of IDG Technology Venture Investment (IDGVC), is used to seeing 60-fold and sometimes 120-fold returns on investment.

The POM-DOM piezophilic microorganism continuum(PDPMC)—The role of piezophilic microorganisms in the global ocean carbon cycle

The deep ocean piezosphere accounts for a significant part of the global ocean,hosts active and diverse microbial communities which probably play a more important role than hitherto recognized in the global ocean carbon cycle.The conventional biological pump concept and the recently proposed microbial carbon pump mechanism provide a foundation for our understanding of the role of microorganisms in cycling of carbon in the ocean.However,there are significant gaps in our knowledge and a lack of mechanistic understanding of the processes of microbially-mediated production,transformation,degradation,and export of marine dissolved and particulate organic matter(DOM and POM)in the deep ocean and the ecological consequence.Here we propose the POM-DOM piezophilic microorganism continuum(PDPMC)conceptual model,to address these important biogeochemical processes in the deep ocean.We propose that piezophilic microorganisms(bacteria and archaea)play a pivotal role in deep ocean carbon cycle where microbial production of exoenzymes,enzymatic breakdown of DOM and transformation of POM fuels the rapid cycling of marine organic matter,and serve as the primary driver for carbon cycle in the deep ocean.

Intensified Impact of the Equatorial QBO in August–September on the Northern Stratospheric Polar Vortex in December–January since the Late 1990s

This study reveals an intensified impact of the equatorial quasi-biennial oscillation(QBO)in August–September(QBO_AS)on the northern stratospheric polar vortex(SPV)in December–January(SPV_DJ)since the late 1990s.The unstable relationship may be related to the differences in the deep convection anomaly over the tropical western Pacific and Indian Oceans in October–November(ON)related to the QBO_AS prior to and after the late 1990s.During 1998–2017,the easterly phase of the QBO_AS is accompanied by a colder tropical tropopause in ON,which enhances the deep convective activity over the tropical western Pacific and suppresses it over the Indian Ocean.The deep convection anomaly generates anomalous Rossby waves that propagate into the northern mid-to-high latitudes to constructively interfere with the climatological wavenumber-1 and wavenumber-2 components,thereby resulting in enhanced upward-propagating tropospheric planetary-scale waves and a weakened SPV_DJ anomaly.During1979–1997,however,the deep convection anomaly over the tropical western Pacific and Indian Oceans in ON related to the easterly phase of the QBO_AS is weaker and shifts eastward,which excites the anomalous Rossby waves to constructively/destructively interfere with the climatological wavenumber-1 component in the midlatitudes/high latitudes,thereby weakening the upward-propagating planetary-scale waves and leading to a weaker linkage with the SPV_DJ.Further analyses reveal that the unstable relationship may be associated with the interdecadal differences in deep convection over the tropical western Pacific and Indian Oceans and the upward-propagating tropospheric planetary-scale waves in ON.