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Journey into the deep : discovering new ocean creatures
\"Join scientists on a journey from coastlines to the deep seafloor and meet the weird, wonderful, and unforgettable creatures they discovered along the way\"--P. [4] of cover.
Book
Geomagnetic depth sounding analysis of the electrical conductivity of the mid-mantle beneath Taiwan
The electrical conductivity structure of the mid-mantle at depths of 300–900 km beneath Taiwan was investigated for the first time by applying geomagnetic depth sounding (GDS) to geomagnetic field data. These data were obtained by six Taiwanese observatories and three observatories outside Taiwan. We refine the conductivity estimates by addressing distortions due to the ocean induction effect, which is caused by the contrast in electrical conductivity between the highly resistive continental crust and highly conductive seawater and oceanic sediments. To accurately correct for this effect, we employed a high-resolution (0.1° × 0.1°) three-dimensional conductivity model in a spherical coordinate system with locally refined horizontal meshing. Simulations indicated that the ocean induction effect could best be reproduced using a value of 100 Ω m for the crustal resistivity on land, which is significantly lower than values used in previous global studies. The corrected GDS responses were then inverted to obtain one-dimensional electrical conductivity–depth profiles for each of the six Taiwanese observing sites. The average conductivity profiles showed an increase in conductivity with depth, from 0.06 S m
−1
at 300 km to 0.86 S m
−1
at 900 km. In the upper mantle, the south-eastern part of Taiwan is more conductive than the north-western part. At greater depths, the conductivity values were in line with those in global models, indicating a more homogeneous lower mantle structure. The results of this study enhance the understanding of mantle dynamics beneath Taiwan and demonstrate the critical role of precise ocean effect corrections in GDS analysis.
Graphical Abstract
Journal Article
The Bathysphere book : effects of the luminous ocean depths
\"A gorgeous account of William Beebe's 1934 Bathysphere expedition, the first-ever deep-sea voyage to the otherworldly environment 3,024 feet below sea level\"-- Provided by publisher.
Book
Evidence of Ice‐Rich Layered Deposits in the Medusae Fossae Formation of Mars
Subsurface reflectors in radar sounder data from the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express spacecraft indicate significant dielectric contrasts between layers in the Martian Medusae Fossae Formation (MFF). Large density changes that create dielectric contrasts are less likely in deposits of volcanic ash, eolian sediments, and dust, and compaction models show that homogeneous fine‐grained material cannot readily account for the inferred density and dielectric constant where the deposits are more than a kilometer thick. The presence of subsurface reflectors is consistent with a multi‐layer structure of an ice‐poor cap above an ice‐rich unit analogous to the Martian Polar Layered Deposits. The volume of an ice‐rich component across the entire MFF below a 300–600 m dry cover corresponds to a global equivalent layer of water of ∼1.5 to ∼2.7 m or ∼30%–50% of the total estimated in the North Polar cap. Plain Language Summary The Medusae Fossae Formation (MFF), located near the equator of Mars along the dichotomy boundary between the lowlands of the northern hemisphere and the cratered highlands of the southern hemisphere, is one of the largest and least understood deposits on Mars. The Mars Advanced Radar for Subsurface and Ionospheric Sounding radar sounder detects echoes in MFF deposits that occur between the surface and the base which are interpreted as layers within the deposit like those found in Polar Layered Deposits of the North and South Poles. The subsurface reflectors suggest transitions between mixtures of ice‐rich and ice‐poor dust analogous to the multi‐layered, ice‐rich polar deposits. An ice‐rich part of the MFF deposit corresponds to the largest volume of water outside the polar caps, or a global equivalent layer of water of ∼1.5 to ∼2.7 m. Key Points Mars Advanced Radar for Subsurface and Ionospheric Sounding radar sounder data reveals layering in the Medusae Fossae Formation (MFF) deposits Layers are likely due to transitions between mixtures of ice‐rich and ice‐poor dust, analogous to those in Polar Layered Deposits An ice‐rich portion of the MFF deposit may contain the largest volume of water in the equatorial region of Mars
Journal Article
The deepest map : the high-stakes race to chart the world's oceans
\"The dramatic and action-packed story of the last mysterious place on earth--the world's seafloor--and the deep-sea divers, ocean mappers, marine biologists, entrepreneurs, and adventurers involved in the historic push to chart it, as well as the opportunities, challenges, and perils this exploration holds now and for the future\"-- Provided by publisher.
Book
All-Sky Microwave Radiance Assimilation in NCEP’s GSI Analysis System
The capability of all-sky microwave radiance assimilation in the Gridpoint Statistical Interpolation (GSI) analysis system has been developed at the National Centers for Environmental Prediction (NCEP). This development effort required the adaptation of quality control, observation error assignment, bias correction, and background error covariance to all-sky conditions within the ensemble–variational (EnVar) framework. The assimilation of cloudy radiances from the Advanced Microwave Sounding Unit-A (AMSU-A) microwave radiometer for ocean fields of view (FOVs) is the primary emphasis of this study. In the original operational hybrid 3D EnVar Global Forecast System (GFS), the clear-sky approach for radiance data assimilation is applied. Changes to data thinning and quality control have allowed all-sky satellite radiances to be assimilated in the GSI. Along with the symmetric observation error assignment, additional situation-dependent observation error inflation is employed for all-sky conditions. Moreover, in addition to the current radiance bias correction, a new bias correction strategy has been applied to all-sky radiances. In this work, the static background error variance and the ensemble spread of cloud water are examined, and the levels of cloud variability from the ensemble forecast in single- and dual-resolution configurations are discussed. Overall, the all-sky approach provides more realistic simulated brightness temperatures and cloud water analysis increments, and improves analysis off the west coasts of the continents by reducing a known bias in stratus. An approximate 10% increase in the use of AMSU-A channels 1–5 and a 12% increase for channel 15 are also observed. The all-sky AMSU-A radiance assimilation became operational in the 4D EnVar GFS system upgrade of 12 May 2016.
Journal Article
The underworld : journeys to the depths of the ocean
\"From New York Times bestselling author Susan Casey, an awe-inspiring portrait of the mysterious world beneath the waves, and the men and women who seek to uncover its secrets For all of human history, the deep ocean has been a source of wonder and terror, an unknown realm that evoked a singular, compelling question: What's down there? Unable to answer this for centuries, people believed the deep was a sinister realm of fiendish creatures and deadly peril. But now, cutting-edge technologies allow scientists and explorers to dive miles beneath the surface, and we are beginning to understand this strange and exotic underworld: A place of soaring mountains, smoldering volcanoes, and valleys 7,000 feet deeper than Everest is high, where tectonic plates collide and separate, and extraordinary life forms operate under different rules. Far from a dark void, the deep is a vibrant realm that's home to pink gelatinous predators and shimmering creatures a hundred feet long and ancient animals with glass skeletons and sharks that live for half a millennium-among countless other marvels. Susan Casey is our premiere chronicler of the aquatic world. For The Underworld she traversed the globe, joining scientists and explorers on dives to the deepest places on the planet, interviewing the marine geologists, marine biologists, and oceanographers who are searching for knowledge in this vast unseen realm. She takes us on a fascinating journey through the history of deep-sea exploration, from the myths and legends of the ancient world to storied shipwrecks we can now reach on the bottom, to the first intrepid bathysphere pilots, to the scientists who are just beginning to understand the mind-blowing complexity and ecological importance of the quadrillions of creatures who live in realms long thought to be devoid of life. Throughout this journey, she learned how vital the deep is to the future of the planet, and how urgent it is that we understand it in a time of increasing threats from climate change, industrial fishing, pollution, and the mining companies that are also exploring its depths. The Underworld is Susan Casey's most beautiful and thrilling book yet, a gorgeous evocation of the natural world and a powerful call to arms\"-- Provided by publisher.
Book
Meteosat Third Generation (MTG)
Within the next couple of years, the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) will start the deployment of its next-generation geostationary meteorological satellites. The Meteosat Third Generation (MTG) is composed of four imaging (MTG-I) and two sounding (MTG-S) platforms. The satellites are three-axis stabilized, unlike the two previous generations of Meteosat that were spin stabilized, and carry two sets of remote sensing instruments each. Hence, in addition to providing continuity, the new system will provide an unprecedented capability from geostationary orbit. The payload on the MTG-I satellites are the 16-channel Flexible Combined Imager (FCI) and the Lightning Imager (LI). The payloads on the MTG-S satellites are the hyperspectral Infrared Sounder (IRS) and a high-resolution Ultraviolet–Visible–Near-Infrared (UVN) sounder Sentinel-4/UVN, provided by the European Commission. Today, hyperspectral sounding from geostationary orbit is provided by the Chinese Fengyun-4A (FY-4A) satellite Geostationary Interferometric Infrared Sounder (GIIRS) instrument, and lightning mappers are available on FY-4A and on the National Oceanic and Atmospheric Administration (NOAA) GOES-16 and GOES-17 satellites. Consequently, the development of science and applications for these types of instruments have a solid foundation. However, the IRS, LI, and Sentinel-4/UVN are a challenging first for Europe in a geostationary orbit. The four MTG-I and two MTG-S satellites are designed to provide 20 and 15.5 years of operational service, respectively. The launch of the first MTG-I is expected at the end of 2022 and the first MTG-S roughly a year later. This article describes the four instruments, outlines products and services, and addresses the evolution of the further applications.
Journal Article
Global Predicted Bathymetry Using Neural Networks
A coherent portrayal of global bathymetry requires that depths are inferred between sparsely distributed direct depth measurements. Depths can be interpolated in the gaps using alternate information such as satellite‐derived gravity and a mapping from gravity to depth. We designed and trained a neural network on a collection of 50 million depth soundings to predict bathymetry globally using gravity anomalies. We find the best result is achieved by pre‐filtering depth and gravity in accordance with isostatic admittance theory described in previous predicted depth studies. When training the model, if the training and testing split is a random partition at the same resolution as the data, the training and testing sets will not be independent, and model misfit is underestimated. We solve this problem by partitioning the training and testing set with geographic bins. Our final predicted depth model improves on old predicted depth model RMSE by 16%, from 165 to 138 m. Among constrained grid cells, 80% of the predicted values are within 128 m of the true value. Improvements to this model will continue with additional depth measurements, but predictions at higher spatial resolution, being limited by upward continuation of gravity, should not be attempted with this method. Plain Language Summary Only a fraction of the seafloor has been mapped by shipboard measurements. In the unmapped regions of the ocean, we must estimate the depth of the seafloor using information from the Earth's gravity field. Models predicting seafloor depth using gravity typically determine the linear relationship between gravity and depth in some regions and use the established relationships to make global predicted depth maps. Here, we describe a new method for predicting depth globally using gravity, decades of shipboard depth measurements, and a neural network regression. Ultimately, our model shows a clear improvement over the reference model. Key Points We present a new method for global bathymetry prediction using a machine learning algorithm The new predicted depth model improves on the reference model by all error metrics
Journal Article
A water-rich zone crossing the 660 km discontinuity beneath the SE Tibetan Plateau revealed by one-dimensional electrical conductivity modelling
Water plays a key role in the circulation of mantle material within the Earth. Recent research has shown that water could be transported into the lower mantle by high-angle subduction, such as beneath the SE Tibetan Plateau, where the Indian (Tethys) plate has undergone long-term high-angle subduction. However, due to the scarcity of geophysical observations, it remains uncertain whether the plate can carry water into the deep mantle. Here, we report three one-dimensional conductivity models of the mantle inverted from C-responses from geomagnetic depth sounding (GDS) data in the area. The electrical conductivity of the lower mantle transition zone (LMTZ) and uppermost lower mantle (ULM) beneath the Xichang (XIC) station is higher than the 1-D global mean mantle conductivity derived from the inversion of satellite-measured geomagnetic data, while beneath the Chengdu (CDU) and Chongqing (CHQ) stations, it is lower than the global mean. Together with the results of seismic imaging and experimental models of minerals at high temperatures and pressures, the high-conductivity in the XIC model can be explained by water contents of 3.06–3.15 wt.% in the LMTZ and 0.28–0.51 wt.% in the ULM. The conductivity models confirm that the subducting Tethys oceanic slab carried water into the LMTZ and ULM beneath the XIC.
Graphical Abstract
Journal Article