bluuebunny/crossref_metadata_2025 huggingface dataset:
Water management and climate change monitoring in Tunisia and Egypt using remote sensing techniques
Authors: Paloscia Simonetta , Fontanelli Giacomo , Pettinato Simone , Santi Emanuele , Ramat Giuliano , Da Ponte Emmanuel , Abdel-Wahab Magdy , Hesham Yassmina , Ouessar Mohamed , Dhaou Hanen , Kassouk Zeineb , Chabane Zohra Lili
Published: March 2020

This project deals with the implementation of an innovative water management system in Mediterranean countries (i.e. Tunisia and Egypt), which suffer from chronic water scarcity, together with two European countries (Germany and Italy). The consortium is developing and applying synergic methods and algorithms for investigating the water cycle, using remote sensing techniques.

The focus is on the use of satellite data (both optical and microwave) for monitoring vegetation cover and water status along with soil moisture temporal evolutions in order to improve the knowledge of the water cycle in arid areas. Both local and regional monitoring are carried out in order to investigate different spatial scales.

Environmental models and algorithms for the retrieval of hydrological parameters have been developed in the frame of this project in order to match the main goal of the project, i.e. to propose practical and cost-effective solutions for driving and updating a method for the sustainable use of water in agriculture. 

An optimized management of water resources for cultivated lands on Egyptian Delta (Northern part) and Tunisian territory will be realized by analyzing the available spatial and temporal data for the areas of interest appropriately selected for this purpose. As such, an efficient water use, equitable distribution of water resources, community participation in decisions, and sustainable system operation over time can be supported.

First of all, we aim to localize different crop and irrigation techniques for the study regions. This information is required as a basis for further investigations and assessments. Secondly, the water efficiency for different lands, crop types and irrigation systems will be assessed.

Afterwards, possible improvements in agricultural practice with respect to climate change scenarios and information on water efficiency will be determined by rating the outcome from the assessment.
Remote Sensing of Surface Soil Moisture from FengYun MicroWave Radiation Imager (MWRI) Data Using a Machine Learning Technique
Authors: Zhang Sibo , Yao Wei
Published: March 2020

In the past, soil moisture can be retrieved from microwave imager over most of land conditions. However, the algorithm performances over Tibetan Plateau and the Northwest China vary greatly from one to another due to frozen soils and surface volumetric scattering. The majority of western Chinese region is often filled with invalid retrievals. In this study, Soil Moisture Operational Products System (SMOPS) products from NOAA are used as the learning objectives to train a  machine learning (random forest) model for FY-3C microwave radiation imager (MWRI) data with multivariable inputs: brightness temperatures from all 10 MWRI channels from 10 to 89 GHz, brightness temperature polarization ratios at 10.65, 18.7 and 23.8 GHz, height in DEM (digital elevation model) and statistical soil porosity map data. Since the vegetation penetration of MWRI observations is limited, we exclude forest, urban and snow/ice surfaces in this work. It is shown that our new method performs very well and derives the surface soil moisture over Tibetan Plateau without major missing values. Comparing to other soil moisture data, the volumetric soil moisture (VSM) from this study correlates with SMOPS products much better than the MWRI operational L2 VSM products. R2 score increases from 0.3 to 0.6 and ubRMSE score improves significantly from 0.11 m3 m-3 to 0.04 m3 m-3 during the time period from 1 August 2017 to 31 May 2019. The spatial distribution of our MWRI VSM estimates is also much improved in western China. Moreover, our MWRI VSM estimates are in good agreement with the top 7 cm soil moisture of ECMWF ERA5 reanalysis data: R2 = 0.62, ubRMSD = 0.114 m3 m-3 and mean bias = -0.014 m3 m-3 for a global scale. We note that there is a risk of data gap of AMSR2 from the present to 2025. Obviously, for satellite low frequency microwave observations, MWRI observations from FY-3 series satellites can be a benefit supplement to keep the data integrity and increase the data density, since FY-3B\-3C\-3D satellites launched in November 2010\September 2013\November 2017 are still working today, and FY-3D is designed to work until November 2022.
Vilcanota river watershed Hydrology - Peru: Evolution in a changing climate and soil cover.
Authors: Saavedra Danny , Mendoza Pablo , Vargas Ximena
Published: March 2020

Vilcanota river watershed is located in Cusco region in Peruvian Southeast mountain, on the Atlantic slope. This watershed is important for  cities located within the Cusco region, since it supplies water for human consumption and for agricultural and livestock production. Therefore, it is important to understand the hydrological behavior of the watershed, in order to determine water availability for the past, present and future periods, and to be able to make better decisions.

We analyze  evolution of hydrology in the Vilcanota river watershed, with changing climates and ground cover. To achieve the goal, we propose the use of a flexible modeling platform, such as the unified approach to process-based hydrological modeling called Structure for Unifuing Multiple Modeling Alternatives (SUMMA), which contains a general set of conservation equations, providing flexibility to experiment with different spatial representations, different flux parameterizations, different model parameter values ​​and different time stepping schemes. This modeling platform will allow us to reduce the uncertainty in the structure of hydrological models and thus obtain correct results for the right reasons. The historical data, meteorological forcing, and the streamflow measurement data, taken from the Peruvian National Meteorological and Hydrological Service (SENAMHI) database, is  used to run  the model at a subdaily  level. The performance of the model, is evaluated through objective functions  selected to adequately represent the behavior of the hydrology of the watershed, both at high and low flows. allowing us to obtain good results in hydrology projections during wet and dry periods.

Preliminary results show that in the historical data of the watershed there is a slight trend in the increase in runoff, attributed to the change in ground cover.
Thermospheric composition response to Sudden Stratospheric Warmings observed by the Global-Scale Observations of the Limb and Disk (GOLD) instrument
Authors: Oberheide Jens , Pedatella Nicholas , Gan Quan , Kumari Komal , Burns Alan , Eastes Richard
Published: March 2020

Observations from the recently launched Global-Scale Observations of the Limb and Disk (GOLD) instrument on the geostationary SES-14 communications satellite provide the first observational proof for the impact of stratospheric weather, that is, polar vortex dynamics during a Sudden Stratospheric Warming (SSW), on the composition of the thermosphere. During the early January 2019 SSW, GOLD observes a >10% O/N2 column density ratio depletion in both hemispheres unrelated to geomagnetic activity. The data and supporting TIE-GCM and WACCM-X simulations show that enhanced global-scale wave activity during the SSW causes an enhanced wave driving of the lower thermosphere zonal mean circulation that leads to a reduction in lower thermosphere atomic oxygen, which then propagates through molecular diffusion into the upper thermosphere. The observed composition changes will likely impact Earth's ionospheric plasma environment as well and imply another pathway for SSW impacts on space weather, in addition to dynamo processes.
Highly accurate analytical footprint model for general stratification of the atmosphere
Authors: Krapez Jean-Claude , Ky Gregoire , Sarrat Claire
Published: March 2020

The flux footprint (or so-called source area) is the zone of the surface that contributes to a measured vertical flux (e.g. of water vapor or carbon dioxide) between the ground and the atmosphere: Footprint models are then used to derive location and size of the source area and for interpretation of flux-tower measurements, in particular to estimate the contribution of passive scalar sources to these measured fluxes, and to combine measured fluxes with remotely sensed data.

Existing footprint models are of two types: either they derive from the solution of an advection-diffusion differential equation or they result from a parameterization based on numerical simulations performed with a Lagrangian stochastic particle dispersion model. Models of the first type are essentially based on the hypothesis of power-law profiles of the mean wind speed u(z) and eddy diffusivity K(z). Our objective was to suppress this constraint and to build a footprint model for any type of profile, in particular Monin-Obukhov surface-layer profiles.

The model was developed in the frame of the K-theory. Homogeneous conditions were assumed in the horizontal plane and the alongwind diffusion term was neglected with respect to the advection term. A semi-analytical tool has been developed to cope with any type of atmosphere stratification. Applying a dedicated quadrupole method, the boundary layer is divided into a series of sublayers and an extended power law model is applied in each of them (10 to 15 sublayers are enough to reach an error of less than 0.1%, whatever the atmosphere stability).

In the end, a highly accurate estimation of the footprint can be obtained very quickly for any profile of wind speed and eddy diffusivity.
Compact High Resolution QIT-Mass Spectrometers for Lunar and Planetary Applications
Authors: Maiwald Frank , Simcic Jurij , Nikolic Dragan , Belousov Anton , Madzunkov Stojan
Published: March 2020

The JPL Mass Spectrometer Team develops components and instruments based on a Paul quadrupole ion trap mass spectrometer (QIT-MS) for Earth and space applications. Over the past 20 years, the team has miniaturized the QIT-MS and verified its performance successfully for the International Space Station. The technology was demonstrated with the recent delivery of the first Spacecraft Atmosphere Monitor (S.A.M.) to the International Space Station (ISS).

The next step is to build a QIT-MS intendent to investigate the lunar exosphere via a funded ROSES 2019, DALI/NASA proposal over the next three years.

The QIT-MS will be the first in-situ lunar mass spectrometer capable of identifying and quantifying exosphere species (ex. H, H2, 3He, 4He, Ne, N2, O2, Ar, CH4, CO, CO2, Kr, Xe, OH, H2O) with abundance greater than 10 molecules/cm3 [1]. The combination of low mass (7.5 kg), low power (max. 30W with heater bulb on), high sensitivity (0.003 counts/cm3/sec), and ultrahigh precision (1.7 x 10-10 Torr, Kr measured continuously for 7 hours yielded a 0.6 ‰ precision on the 86Kr/84Kr ratio) will provide an unpreceded inside of the scientific processes in the lunar exosphere.

Other implementation approaches will be discussed, which entail the development of different frontends to expand applications for dense atmospheres (ex. Venus) or liquids (ex. ocean worlds). Most of these developments can be used to determine contaminants in the air, water, or volatile in solids.

[1] G. Avice, A. Belousov, K. A. Farley, S. M. Madzunkov, J. Simcic, D. Nikolic, M. R. Darrach and C. Sotin, “High-precision measurements of krypton and xenon isotopes with a new static-mode quadrupole ion trap mass spectrometer,” JAAS, Vol 34, January 2019

 

Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109

 
Redox chemical processes of iodine species with inorganic compounds in ice
Authors: Kim Kitae
Published: March 2020

Ice is ubiquitous and one of the most important environmental reaction media on earth. Generally, chemical reactions take place slowly when temperature decreases according to Arrhenius Equation(k=A·e-EA/RT). Recently, it has been found that several chemical processes are accelerated by freezing compared to those in aqueous phase. Reactive iodine species (I, I2, IO, OIO, HOI) in atmosphere are related to ozone depletion event (ODE) and new particle formation (NPF) in polar troposphere, and finally affect climate change. It was reported that the high concentration of halogen compounds(IO, BrO) in austral spring in Antarctica but the exact mechanism and sources are not fully understood. The biological production of halogens are regarded as the major source of organic and I2. However, the (photo)chemical reactions to produce reactive iodine species are also regarded as possible mechanism to explain the high atmospheric iodine budget. In this presentation, I want to introduce enhanced chemical reaction with laboratory experimental results such as 1)accelerated oxidation of iodide(I-) in ice to produce molecular iodine(I2) and tri-iodide(I3-), 2)nitrite-induced activation of iodate(IO3-) into molecular iodine in frozen solution. The detailed experimental conditions and mechanism will be discussed in the presentation.
Investigating the Temperature Limits of Bentonite Backfilled Repositories: Coupled THMC Modeling, Lab Mockup Testing and Field Experiments
Authors: Birkholzer Jens , Zheng Liange , Rutqvist Jonny , Borglin Sharon , Chang Chun , Chou Chunwei , Wu Yuxin , Kneafsey Tim
Published: March 2020

Compacted bentonite is commonly considered for use as backfill material in emplacement tunnels of nuclear waste repositories because of its low permeability, high swelling pressure, and retardation capacity of radionuclide. To assess whether this material can maintain its favorable features when undergoing heating from the waste package and hydration from the host rock, we need a thorough understanding of the thermal, hydrological, mechanical, and chemical evolution under disposal conditions. Laboratory and field tests integrated with THMC modeling have provided an effective way to deepen such understanding; however, most of this work has been conducted for maximum temperatures around 100°C. In contrast, some international disposal programs have recently started investigations to understand whether local temperatures in the bentonite of up to 200°C could be tolerated with no significant changes in safety relevant properties. For example, the United States disposal program is evaluating the feasibility of geological disposal of large spent nuclear fuel canisters that are currently in dry storage. Direct disposal of these canisters is attractive for economical and safety reasons, but faces the challenge of exposing the bentonite to significant temperatures increases. As a result, strong thermal gradients may induce complex moisture transport processes and bentonite-rock interactions while cementation and perhaps also illitization effects may occur, all of which could  strongly affect the bentonite properties.

Here, we present initial investigations of bentonite behavior exposed to strongly elevated temperatures. We first show results from coupled thermal, hydrological, mechanical and chemical (THMC) simulations of a generic nuclear waste repository in a clay formation with a bentonite-based buffer exposed to a maximum temperature of 200°C. Modeling results illustrate possible performance impacts, such as the time frame and condition of the early unsaturated phase during bentonite hydration, the porosity and permeability after the bentonite becomes fully saturated, and changing in swelling properties. We then discuss preliminary data from a bench-scale laboratory mockup experiment which was designed to represents the strong THMC gradients occurring in a “hot” repository, and we briefly touch on a full-scale field experiment to be conducted soon in the Grimsel Test Site underground research laboratory in Switzerland (referred to as HotBENT, with bentonite exposure from up to 200oC). 
Spatial variations of coda wave attenuation in Andaman-Nicobar subduction zone
Authors: Singh Chandrani , Biswas Rahul , Jaiswal Namrata , Kumar M. Ravi
Published: March 2020

We investigate the spatial variations of coda attenuation (Qc) structure in the tectonically complex Andaman–Nicobar subduction zone (ANSZ), which is one of the most seismically active subduction zones on the Earth. The region constitutes the northernmost part of the Sunda subduction zone, where the Indian plate disappears beneath the Burmese plate along the Burma and Andaman arcs to the east. This is probably the first attempt to map the Qc variations across the whole ANSZ. In a seismically active area, the spatial distribution of Qc is important to evaluate the seismic hazard in relation to tectonics and seismicity.

A total of 289 high-quality events recorded at a network of broad-band stations operational since 2009 are considered for the analysis. The variations in attenuation characteristics at different frequencies reveal a marked contrast from the northern to the southern Andaman region, consistent with the geotectonic diversity of the region. At low frequencies, low Qc values are observed in the northern part of ANSZ in the vicinity of the Narcondum volcanic island, which does not appear in the high-frequency image. The low values are in agreement with the 3-D tomogram, which suggests a distinct low-velocity structure below this volcanic island. The Andaman trench also exhibits a relatively low Qc, which is well correlated with the low-Vp zone. The spatial distributions of Q0 (Qc at 1 Hz) structure of the region are further projected onto three east–west profiles to capture the detailed attenuation characteristics from north to south. Results show that the northernmost part of ANSZ is more attenuative than the southern part, which may be indicative of the changes in physical properties of the crust. The frequency relation parameter (n) shows an inverse correlation with the observed Q0 values. Furthermore, we have observed a good correlation between the Q0 variation and the seismicity pattern of the area that enables us to enhance our understanding about the role of crustal heterogeneity in the earthquake occurrence in this area.
Development of Flood Hazard Map from Probabilistic Embankment Collapse Inflow
Authors: Lee Changhee , Nam Myeong Jun , Lee Jae Young
Published: March 2020

Flood damages caused by abnormal climate changes occur frequently every year. Systems to predict and respond to disasters are required to prepare for flood damages. The embankment overflow and collapse mechanism due to the rapid increase of river water level in flood are quite complex, varied, and uncertain. In this study, changes of river embankment collapse widths and flood inflows were calculated. In this case, the MCS-based probability flood levels were used based on th hydrologcal scenario, which takes into account the uncertainty of the parameters of extreme precipitation through the abnormal frequency analysis. In addition, two-dimensional inundation analysis was performed to estimate flood depth and flood area, and to produce a probabilistic flood hazard map. By quantitatively evaluating the uncertainty of the parameters in consideration of the overall mechanism of flood occurrence, we obtained more reliable predictions of flood depth than conventional deterministic analyses.

 
Global Occurrence Rates of Ionospheric Plasma Density Irregularities Observed by Advanced Ionospheric Probe Onboard FORMOSAT-5 Satellite During Solar Minimum
Authors: Chen Yi-Wun , Chao Chi-Kuang
Published: March 2020

　　A remote sensing satellite, FORMOSAT-5, developed by National Space Organization (NSPO) carried a piggyback science payload, Advanced Ionospheric Payload (AIP), for space weather and seismo-ionospheric precursor study.  To meet the science requirements, AIP could be operated in different measurement modes to obtain various plasma parameters.  The first AIP measurement was performed on 7 September 2017 to obtain the first-orbit data and started routine operation in November the same year.  Global ion density and ion velocity/temperature distributions were available every two days and four days, respectively.  AIP was regularly operated in a sampling rate 1,024 Hz to maximize useful science data.  In this poster, global occurrence rates of pre-midnight low-latitude ionospheric plasma density irregularities will be shown from AIP science data collected since winter 2017.  The results indicate that seasonal variations of the occurrence rates during the solar minimum (2017/11-2019/12) are distributed very similar to but have lower magnitudes than those observations by ROCSAT-1/Ionospheric Plasma and Electrodynamics Instrument dataset (1999-2004) during solar maximum.
Spatial-temporal variations in green and blue water resources, water footprints and water scarcities in a large river basin：a case for the Yellow River Basin
Authors: Xie Pengxuan , Zhuo La , Wu Pute
Published: March 2020

Blue water (surface and ground water) and green water (water stored in unsaturated soil layer and canopy evapotranspiration from rainfall) are the two sources of water generated from precipitation and communicating vessels that define the limits of water resources for both human activities and ecosystems. However, the blue and green water evapotranspiration in irrigated fields and their contribution to blue and green water flows have not been identified in studies conducted on blue and green water resources. In addition, information on intra-annual variations in blue and green water footprints (WFs) is limited. In particular, there is a lack of information on water consumption obtained from hydrological model-based blue and green water assessments at the basin scales. In this study, the Yellow River Basin (YRB) over 2010-2018 was considered as the study case, and the inter- and intra-annual variations in blue and green water resources, WFs and water scarcities were quantified at sub-basin levels. Water resources and WFs were simulated using the Soil and Water Assessment Tool (SWAT) model. The results revealed that the annual average blue and green water resources of the YRB were 119.33 × 109 m3 yr-1 and 296.94 × 109 m3 yr-1, respectively, over the study period. The total amount of green water flow was larger than the total amount of blue water flow each year. The blue and green WFs of the crops in the middle reach were significantly larger than those of the crops in the upper and lower reaches. The annual blue and green water scarcity levels under the consideration of the overall YRB were low. However, several areas in the middle reaches were subject to both blue and green water scarcities at least modest level for a minimum of three months a year. The northern region of the YRB was subject to significant and severe blue water scarcity throughout each year.
The Iimpact of the Iintraseasonal Intensity Variation of Asian Summer Monsoon Anticyclone on Chemical Constituents Distribution in the Upper Troposphere and Lower Stratosphere
Authors: Luo Jiali , Peng Kecheng
Published: March 2020

During the Asian summer monsoon (ASM) season, the stratosphere-troposphere exchange (STE) process has a significant effect on the stratospheric chemical constituent concentration and spatial distribution. In order to further explain the STE process during the ASM season, the impact of ASMA intensity on chemical species within the anticyclone escaping process during the ASM season is studied. Using the MERRA 2, NCEP reanalysis data and MLS satellite data in June, July and August (JJA) of 2004-2017, the relationship between the day-to-day intensity variation of the ASMA and the horizontal distribution of ozone (O3) and carbon monoxide (CO) during the intra-seasonal east-west oscillation is discussed based on an ASMA intensity index we defined. The results show that the intensity of the ASMA varied during the intra-seasonal east-west oscillation. The ASMA intensity index increased continuously from early June and peaked during mid-July to early August. ASMA has a constraints effect on the air inside. Its intra-seasonal oscillation and its intensity influenced the chemical distribution in the upper troposphere and lower stratosphere (UTLS). The distribution of chemical substances during its strong periods (SP) were relatively concentrated than that in weaker periods (WP). The air inside of the ASMA was easier to mix into stratosphere when the intensity was weak, and vice verse. The intensity variation of the ASMA caused by its intra-seasonal oscillation may affect the STE process during the Asian summer monsoon season.
Preliminary absolute paleointensity estimation from a single volcanic-glass grain extracted from an unwelded pyroclastic flow
Authors: Yamamoto Yuhji , Takeda Hiromi , Sato Masahiko , Kawabata Hiroshi
Published: March 2020

Many pyroclastic flows are distributed around Japan. They usually involve volcanic-glass grains. These grains are considered to form at the timing of volcanic eruptions and are expected to have magnetic inclusions consisting of tiny single (titano)magnetites with recording the paleomagnetic field. We have extracted single volcanic-glass grains of pumice-type with a diameter of 0.60-0.84 mm from an unwelded part of the Ito pyroclastic flow deposits (A-Ito, 26-29 ka; Machida and Arai, 2003), Kyusyu, Japan. A series of rock- and paleomagnetic measurements have been made on the grains.

Sixty-seven out of 88 grains had detectable intensities of natural remanent magnetization. Some of such grains were further investigated. Results of low-temperature magnetometry exhibited inflection points at 105-120 K, suggesting magnetite as a main remenence carrier. Stepwise alternating field demagnetization revealed an existence of stable characteristic remanence (ChRM) which was interpreted to be a primary component. 

Tsunakawa-Shaw method (Tsunakawa and Shaw, 1994; Yamamoto et al., 2003), one of the latest absolute paleointensity (API) techniques to date, was applied to selected grains having stable ChRMs. On the application we newly included measurements related to an isothermal remanent magnetization (IRM). Four successful results were obtained by an adoption of IRM corrections, giving an average API value of about 25 μT. This corresponds to a virtual axial dipole moment (VADM) of about 50 ZAm2, which is consistent with the contemporaneous VADM of the sedimentary record (PISO-1500; Channell et al., 2009). 
GGOS Japan: Uniting Space Geodetic Activities in Japan
Authors: Otsubo Toshimichi , Miyahara Basara , Yokota Yusuke , Kurihara Shinobu , Munekane Hiroshi , Watanabe Shun-ichi , Miyazaki Takayuki , Takiguchi Hiroshi , Aoyama Yuichi , Doi Koichiro , Fukuda Yoichi , Matsuo Koji , Jike Takaaki , Matsumoto Takehiro , Ichikawa Ryuichi
Published: March 2020

Since the establishment in 2013, GGOS Japan, formerly known as GGOS Working Group of Japan, has actively contributed to domestic and international space-geodetic activities.  Until it was established, six Japanese agencies with their own backgrounds and missions had individually conducted geodetic observations of GNSS, VLBI, SLR, DORIS and gravimetry in Japan and Antarctica.   GGOS Japan was established to strengthen the collaboration between the agencies and to get connected to international organizations such as IAG and GGOS.

Its core members consist of a chair, a secretary, a lead of the outreach working group, a lead of the DOI working group and representatives of five core techniques.  It is supported by tens of people in Japan and also by its parent entity, IAG subcommittee in Japan.

This presentation will cover our achievement such as assembling our site list, hosting various domestic/international meetings, planning a special issue in a domestic journal, producing its leaflet and website and so on.  Since 2017 it has been approved as an GGOS Affiliate and it is remarkable that Basara Miyahara was elected as GGOS President in 2019.
Designing interventions in the ice sheet/sea level system
Authors: Moore John , Wolovick Mike , Keefer Bowie , Levers Oliver
Published: March 2020

The marine ice sheet instability may have already been initiated in several glaciers in West Antarctica. Hence controlling global temperatures is unlikely to be an effective way of preventing considerable sea level rise. This limits both the utility of greenhouse gas mitigation and solar radiation geoengineering as control mechanisms. Instead we evaluate various other options such as allowing ice shelves to thicken by reducing bottom melting, or slowing ice streams by drying their beds. We consider the engineering limitations, costs, and practical consequences of various designs and how a ladder of implementation might be climbed with regard to learning from Greenland and small-scale field trials. The governance, ethics, legality and societal implications for the local indigenous and global South are also discussed.
Space geodetic study of the 2019 typhoon Hagibis: PWV and crustal subsidence
Authors: Heki Kosuke , Arief Syachrul , Yoshida Mizuki , Wei Zhan
Published: March 2020

Strong typhoons hit the Japanese Islands repeatedly in 2019. Here we study one of these typhoons (2019 #19 Hagibis 915 hPa, 86 casualties) that landed central Japan on Oct.12 (local time) during the Rugby World Cup tournament, using two different space geodetic approaches, i.e. water vapor and crustal deformation. The first approach is the recovery of Precipitable Water Vapor (PWV) using the zenith wet delays (ZWD) estimated by the dense GNSS array in Japan GEONET. Because atmospheric water vapor concentrates in relatively low altitudes, high humidity is often difficult to recognize in ZWDs when the surface altitude is high. To overcome the difficulty, we reconstructed ZWDs, converted to sea-level values, by spatially integrating the tropospheric delay gradient (azimuthal asymmetry of water vapor) vectors. We also calculated convergence of such delay gradients, equivalent to water vapor convergence index (WVCI) proposed by Shoji (2013 Jour. Met. Soc. Japan). We found that very strong rainfall occurs in the region where both reconstructed ZWD and the delay gradient convergence index are high. Next, we studied vertical crustal movements associated with the water load brought by the typhoon, using the two solutions of the GEONET station coordinates, one from the official F3 solution and the other from the UNR data base. We confirmed subsidence down to ~2 cm in multiple regions where severe flood occurred. Such subsidence was observed to recover with a time constant of 1-2 days reflecting rapid drain of rain water to ocean due to large topographic slope and proximity to the sea. We could not identify, however, crustal uplift due to the low atmospheric pressure at the center of the typhoon.
Coupled tropical cyclone seasonal forecasting system over the Northwest Pacific Ocean in NMEFC
Authors: Zhang Yunfei , Li Xiang , Ling Tiejun , Wang Chenqi , Qu Hongyu
Published: March 2020

Tropical cyclone (TC) activity has significant seasonal, interannual and interdecadal variations. Accurate prediction of TC seasonal activities before the onset of the coming TC season (June-November) can provide sufficient time for the government and the public to prepare for tropical cyclone disasters and minimize risks and life losses.
Based on COAWST model, we developed a new regional coupled seasonal forecasting system for the Northwest Pacific Ocean including a series of technology improvements. The results of multi-year hindcast experiments show that the coupled seasonal forecasting system can effectively improve the tropical cyclone frequency and intensity forecast compared to the CFSv2 real-time seasonal forecast, especially the tropical cyclone frequency forecast of the TC exceeding the typhoon level, but there is still a certain gap between the results in the forecasting system and the observed TC frequency and intensity, which is mainly reflected in the fact that the forecasting season has a higher frequency of TCs and the peak of strong TCs is relatively weaker. This gap may be caused by the forecasting bias of the sea surface temperature.
Late Miocene thermal history of the Hengchun Peninsula, Southern Taiwan: Apatite Fission-Track data from the Lilungshan Formation
Authors: Kao Shao-I , Chen Wen-Shan , Chan Tong Hin
Published: March 2020

This study aims to investigate the thermal history regarding the Late Miocene Formation of the Hengchun Peninsula with low-temperature thermal chronometry. The samples used in our study were from Lilungshan Formation, which included quartzite (conglomerates) and sandstones (matrix). Lilungshan Formation was an upper fan or feeder channel deposits in shelf environments. Measurements of paleocurrent indicate that these rocks were transported from the NW to the SE, which may represent its source area is a low-grade metamorphic orogenic belt (Yuli belt). In the Late Miocene, outcrops of Yuli belt were low-grade metamorphic rocks with low metamorphic temperatures. To do so, low-temperature thermal chronometry was applied to measure the time since the Lilungshan Formation cooling below the closure temperature. Apatite Fission-track thermochronology is used in this study, which is a radiometric dating method that refers to thermal histories of rocks within the closure temperature range of 110–135°C.

Our study indicates that the pooled age of apatite fission tracks of conglomerates is 3.3–5 Ma and the grain ages of sandstones are below 5 Ma. Those ages are lower than the formation age of Lilungshan Formation (NN11, > 5.6 Ma). In addition, the grain ages spectrum of sandstones is partial annealing, which implies that the conglomerate has suffered from the thermal event and rapidly brought to the earth’s surface within 4 Ma. This study also compares data of previous studies with regard to the fission tracks of conglomerates in Southern Taiwan and confirms the existence of thermal events. With the assumption that the thermal gradient of the accretionary prism is 40–45°C/km, we can suggest that Lilungshan Formation was located 3 km below the earth's surface in roughly 4 Ma.

 

Keywords: Hengchun Peninsula, Lilungshan Formation, Apatite Fission Track, thermal history, chronometry, Late Miocene
Was the 2019 Ms6.0 Changning earthquake in Sichuan, China caused by human activities? —— Analysis of fault structure and seismogenic mechanism based on InSAR
Authors: Gao Hua , Liao Mingsheng , Xu Wenbin , Liu Xiaoge
Published: March 2020

On June 17, 2019, an Ms 6.0 earthquake occurred in Changning, Sichuan, China (the Changning event), which is the largest earthquake within 50 km of the area since records began. It has attracted great attentions as this region is one of the largest shale gas production areas in China. The cause, the fault structure, and the earthquake effects remain the center of debates.

Using Interferometric Synthetic Aperture Radar (InSAR) data, we measure the coseismic deformation and build the fault models of the Changning event and two earlier Ms>5.0 earthquakes (P1:2018/12/16 Ms5.7 and P2:2019/1/3 Ms5.3) using Sentinel-1 and ALOS2 satellite data. From the coseismic interference of ALOS2, the deformation caused by P1, P2, and the Changning event as well as some of their aftershocks can be clearly identified. The deformation caused by the Changning event affects an area of about 150 km2 and the surface deformation is mainly uplift with a maximum of 17.2 cm (towards the satellite). We obtain two fault models for the Changning event. The model inclining southwest has a smaller fitting error than the model inclining northeast and is more consistent with the distribution characteristics of aftershocks and local underground structure. The final model shows that the Changning event was caused by a fault with left-lateral strike and thrust slip. The strike is 124.9° with a dip angle of 49.8°. The inversed seismic moment is 4.79×1017 Nm, corresponding to Mw 5.75.

On the basis of the fault models, we analyze the cause of the Changning earthquake from the following three aspects: (1) Stress change. The cumulative stress change of P1 and P2 on the Changning event fault is less than 0.1 MPa, which is too small to trigger an Ms 6.0 earthquake. Therefore, there is no direct triggering relationship between the Changing event and event P1 or P2. (2) Aftershock distribution. The aftershocks of the Changning event are negatively correlated with time. The Time-Number curve of the aftershocks well obeys the Omori-type aftershocks law. It is inconsistent with the characteristics of a triggered or induced earthquake which has more pre-earthquakes and rapidly decreasing aftershocks. (3) Tectonic backgrounds. The movement of the Changning earthquake fault is accord with the local tectonic motion. Moreover, the causative fault we inferred coincides with a fault located in the basement, which was found by the seismic reflection profile analysis. The fault in the basement is likely to be related to the Changning earthquake.

Therefore, there is no direct evidence showing that the Changning earthquake was induced by shale gas production or other human activity. We consider that the event is a naturally tectonic earthquake.
Evaluation of global ocean tide models based on tidal gravity observations in China
Authors: Tan Hongbo , Shen Chongyong , Wu Guiju
Published: March 2020

Solid Earth is affected by tidal cycles triggered by the gravity attraction of the celestial bodies. However, about 70% the Earth is covered with seawater which is also affected by the tidal forces. In the coastal areas, the ocean tide loading (OTL) can reach up to 10% of the earth tide, 90% for tilt, and 25% for strain (Farrell, 1972). Since 2007, a high-precision continuous gravity observation network in China has been established with 78 stations. The long-term high-precision tidal data of the network can be used to validate, verifying and even improve the ocean tide model (OTM).

In this paper, tidal parameters of each station were extracted using the harmonic analysis method after a careful editing of the data. 8 OTMs were used for calculating the OTL. The results show that the Root-Mean-Square of the tidal residuals (M0) vary between 0.078-1.77 μgal, and the average errors as function of the distance from the sea for near(0-60km), middle(60-1000km) and far(>1000km) stations are 0.76, 0.30 and 0.21 μgal. The total final gravity residuals (Tx) of the 8 major constituents (M2, S2, N2, K2, K1, O1, P1, Q1) for the best OTM has amplitude ranging from 0.14 to 3.45 μgal. The average efficiency for O1 is 77.0%, while 73.1%, 59.6% and 62.6% for K1, M2 and Tx. FES2014b provides the best corrections for O1 at 12 stations, while SCHW provides the best for K1 ,M2and Tx at 12,8and 9 stations. For the 11 costal stations, there is not an obvious best OTM. The models of DTU10, EOT11a and TPXO8 look a litter better than FES2014b, HAMTIDE and SCHW. For the 17 middle distance stations, SCHW is the best OTM obviously. For the 7 far distance stations, FES2014b and SCHW model are the best models. But the correction efficiency is worse than the near and middle stations’.

The outcome is mixed: none of the recent OTMs performs the best for all tidal waves at all stations. Surprisingly, the Schwiderski’s model although is 40 years old with a coarse resolution of 1° x 1° is performing relative well with respect to the more recent OTM. Similar results are obtained in Southeast Asia (Francis and van Dam, 2014). It could be due to systematic errors in the surroundings seas affecting all the ocean tides models. It's difficult to detect, but invert the gravity attraction and loading effect to map the ocean tides in the vicinity of China would be one way.
Crustal structure from offshore wide-angle seismic data: Application to South Yellow Sea
Authors: zhao weina , wu zhiqiang , shi hongcai , xie hui
Published: March 2020

South Yellow Sea was a component of the circum-Pacific continental margin active belt, developing on the marine basement during pre-Paleozoic and mid-Paleozoic. The lack of detail in the offshore seismic model in the crustal levels means that the deep structure remains ambiguous. We processed the offshore wide-angle seismic data from 30 sections that were acquired in 2013 in order to achieve a continuous 2-D velocity and interface model using Rayinvr. The final velocity/interface model along the survey lineshows significant horizontal and vertical variations. The moho depth achieved in this paper (32-36 km) is consistent with those from previous studies, without a root. Two faults mark the gradient locations in the velocity and the changes in the interfaces that separate this high-velocity anomaly from low-velocity bodies. The three velocity bodies correlate well with the regional geological structures (Qianliyan Uplift, Northern Depression, Central Uplift) that are projected onto our model.

Beneath the Northern Depression, the Permian and Triassic strata such as the Qinglong Formation are denuded on a large scale combining velocity model and multi-channel seismic data. Jurassic and Cretaceous strata rest unconformably on the marine residual strata in the Mesozoic and Paleozoic. However, the Triassic strata (Qinglong Formation) and Permian strata (Dalong and Longtan Formations) are preserved in the Central Uplift. In other words, the uplift and denudation in the orogeny generally appear stronger in the north than in the south.

Previous geological and geophysical studies have suggested that abundant normal faults with NE-SW trend played an important role in the tectonic evolution of the South Yellow Sea. More specifically, investigations reveal that the Jiashan-Xiangshui-Qianliyan fault is the boundary between the Qianliyan Uplift and Northern Depression in the sedimentary formations. We suggest that normal faults terminate at the upper crust after passing through the sedimentary layers. Marked velocity changes and interface fluctuations are observed in the middle and lower crust beneath the northern South Yellow Sea, where we infer a NW-dipping fault. In other words, the deep NW-dipping fault is the deep footprint of fault system in the South Yellow Sea and appears a normal fault from the velocity feature. This finding indicates that shallow faults in the northern South Yellow Sea could converge towards the deeper crust.
Deglaciation of the Kola Peninsula, Arctic Russia, during the Last Glacial-Interglacial Transition
Authors: Boyes Benjamin , Linch Lorna , Pearce Danni
Published: March 2020

The glacial history of the Kola Peninsula, northwest Arctic Russia, during the Last Glacial-Interglacial Transition (LGIT; c. 18-10 ka) is poorly understood, with some researchers suggesting that the region was glaciated by the Fennoscandian Ice Sheet (FIS; e.g. Hughes et al., 2016), and others suggesting that it was glaciated by an independent Ponoy Ice Cap (e.g. Astakhov et al., 2016). Furthermore, it is unclear if and where there was a periodic ice standstill during the Younger Dryas (c. 12.9-11.7 ka) cold stadial. This is the largest sector of Fennoscandia where glaciation is poorly constrained, which stems from low resolution geomorphological mapping, a lack of sedimentary analyses, and limited dating of glacial landforms and deposits on the Kola Peninsula.

Initial interpretations of geomorphological mapping and sedimentological analyses are presented. High resolution geomorphological mapping has, so far, demonstrated that the Kola Peninsula was glaciated by the FIS, which flowed from the Scandinavian mountains in the west and across the shield terrain of the Kola Peninsula, and not an independent Ponoy Ice Cap, as indicated by the west-east orientation of glacial lineations (e.g. drumlins, crag and tails, mega-scale glacial lineations), moraines, and meltwater channels. Up to four ice streams located in the western Kola Peninsula and the White Sea demonstrated in the glacial lineation record have also been identified. Furthermore, the Younger Dryas margin is proposed to be aligned north-south across the Kola Peninsula, flowing around the Khibiny Mountains, and forming an ice lobe in the White Sea, which is demonstrated by the moraine and meltwater landform assemblage. Moraines and lateral meltwater channels also suggest the Monche-tundra Mountains were exposed as nunataks, and that there were independent cirque and valley glaciers in the Lovozero and Khibiny Mountains at the periphery of the FIS during the Younger Dryas. In addition, glaciotectonised sediments identified in sedimentary analyses indicates the FIS underwent sustained readvances during retreat. This research will provide crucial empirical data for validating numerical model simulations of the FIS, which in turn will further our understanding of (de)glacial dynamics in other Arctic, Antarctic, and Alpine regions.

 

Astakhov, V., Shkatova, V., Zastrozhnov, A. and Chuyko, M. (2016). Glaciomorphological map of the Russian Federation. Quaternary International, 420, pp.4-14.

Hughes, A.L., Gyllencreutz, R., Lohne, Ø.S., Mangerud, J. and Svendsen, J.I. (2016). The last Eurasian ice sheets - a chronological database and time-slice reconstruction, DATED-1. Boreas, 45(1), pp.1-45.
Resolution-dependent variations of sinking particle trajectories in general circulation models: Implications for data-model comparison in past climate
Authors: Nooteboom Peter , Delandmeter Philippe , Bijl Peter , van Sebille Erik , Dijkstra Henk , von der Heydt Anna
Published: March 2020

Any type of non-buoyant material in the ocean is transported by currents during its sinking journey. This transport can be far from negligible for typical (plankton) particles with a low sinking velocity. To estimate the lateral transport, the material can be modelled as a set of Lagrangian particles advected by currents that are obtained from Ocean General Circulation Models (OGCMs). State-of-the-art OGCMs are often strongly eddying, providing flow fields with a horizontal resolution of  10km on a daily basis. However, many long term climate modelling studies (e.g. in palaeoclimate) rely on low resolution models that cannot capture mesoscale features. The lower model resolution could influence data-model comparisons using Lagrangian techniques, but this is not properly evaluated yet through a direct comparison.

In this study, we simulate the transport of sinking Lagrangian particles using low (1°; non-eddying)  and high (0.1°; eddying) horizontal resolution OGCMs of the present-day ocean, and evaluate the effect of the two resolutions on particle transport. We find major differences between the transport in the non-eddying versus the eddying OGCM (in terms of the divergence of particle trajectories and their mean trajectory). Addition of stochastic noise to the particle trajectory parameterizes the effect of eddies well in some regions (e.g. in the North Pacific gyre).

We recommend to apply sinking Lagrangian particles only in velocity fields with eddying OGCMs, which basically excludes all paleo-simulations. We are currently simulating the equilibrium Eocene (38Ma) climate using an eddying OGCM, to be able to apply these Lagrangian techniques in an eddying ocean of the past. We expect this to lead towards a better agreement between the OGCM and sedimentary fossil microplankton.