bluuebunny/crossref_metadata_2025 huggingface dataset:
Open-source surface watercraft for Riverscape mapping
Authors: Dietrich James , Fonstad Mark , Zettler-Mann Aaron
Published: March 2020

Most river system analyses use either intensive, small-area surveys, or extensive, low-resolution surveys. Recent research trends have shown that both high-resolution and river-extent information are necessary to understand fundamental questions of river processes including patterns of critical habitat, sediment links, and river instability. As part of a larger NSF-funded research project, we have developed an open-source, boat-based mapping approach to measure river geometry, sediment size patterns, hydraulic habitats, and riverbank erosion patterns. The custom catamaran design we have developed integrates off-the-shelf, lower-cost sensors including high-resolution RTK/PPK GPS, inertial measurement (IMU), side-scan sonar, single-beam sonar, temperature, and a multi-camera array for 3D mapping above and below water. The design is meant to be “garage build friendly”, utilizing a minimum number of common tools and basic construction techniques. The sensor package will be user-friendly enough for non-expert use, allowing the boat to be deployed for citizen-science based data collection by loaning it to groups like watershed councils or volunteer conservation organizations. This will allow data to be collected over larger areas in less time than would be possible by “expert” researchers. The boat designs and software are developed as an open-source project and all hardware and software and will be made public as our testing and validation progress.
Vertical distribution of microbial communities and their response to metal(loid)s along vadose zone-aquifer sediments
Authors: Chen Qian , Zhong Sining
Published: March 2020

Microbial community in the vadose zone has been widely investigated. However, how microbial community varies from the vadose zone to deep-subsurface aquifer are poorly understood. In this study, 12 samples from vadose zone and three aquifer sediments were collected along a 42.5 m bore at a typical agricultural land in central China. High-throughput sequencing and multivariate statistical analysis were applied to explore the underlying distributions of bacterial, archaeal and fungal communities, and their response to environmental factors. The results showed that bacterial community changed considerably at vertical scales and essential variation occurred at the third aquifer layer. Actinobacteria (19.5%), NC10 (11.0%), Alphaproteobacteria (7.7%), Gammaproteobacteria (6.9%), and Deltaproteobacteria (6.4%) were most abundant classes in the vadose zone, where Alphaproteobacteria (22.3%), Gammaproteobacteria (20.1%), Actinobacteria (17.7%) and Bacteroidia (6.9%) enriched in the aquifer sediments. Archaeal and fungal communities were relatively more homogenous, with no significant trend as a function of depth. Process analysis further indicated that Selection dominated in bacterial community, whereas stochastic process governed archaeal and fungal communities. Moreover, environment-bacteria interaction analysis revealed that metal(loid)s (especially alkali metals) rather than physiochemical variables highly shaped the bacteria community in the vadose zone-aquifer continuum, where Bacteroidetes exhibited the strongest link to the variation of metal(loid)s. This research extends our knowledge about microbial community’s variation through the vadose zone to deep aquifer sediments in the studied area and similar agricultural areas.
Study on the critical dynamics of compound erosion in the Pisha sandstone area
Authors: Yang Chunxia , Xiao Peiqing , Zhang Pan
Published: March 2020

The Pisha sandstone area which distributed in Ordos of Inner Mongolia was the main source area of Yellow River sediment, The area has a characteristic of serious composite erosion and fragile ecological environment, So, which identifying the critical force occurrence conditions of compound erosion is an important prerequisite to prevent and control the multiple composite erosion. Using the method such as field observation, simulation experiments and literature review, this study preliminarily summarizes the dynamic critical conditions and key influencing factors of water erosion, wind erosion and freeze-thaw erosion.(1)Water erosion is affected by rainfall, rainfall intensity and soil moisture status, Rainfall and rainfall intensity are the two critical factors under the certain soil moisture status. the one critical conditions of water erosion was P > 34mm under the soil moisture of θv≈10%, and the other critical conditions was rainfall intensity I > 1.2mm/min (soil moisture θv＞36%) or rainfall intensity I > 3.1mm/min（soil moisture θv＜4%). (2)The wind erosion is affected by the surface covering particles and soil moisture. When the wind speed reaches more than 5 m/s, the soil particles of diameter d < 0.5 mm will be blown up. So the wind erosion is easier happens on exposed surface and slipped particles. Increasing the surface covering and water content can reduce wind erosion; (3)Freeze-thaw mainly occurs from November to March of each year, which destroys soil structure mainly through soil mass melting and particle fall down. The alternation times and moisture content of freeze-thaw are the key factors that affect freeze-thaw erosion. When the soil moisture is more than 10% and the freeze-thaw alternation is more than 10 times, the freezing and cracking damage is obvious. Therefore, the phenomenon of sliding and peeling off the exposed steep slope is common in Pisha sandstone area. (4)Multi dynamic composite erosion distributed by seasonal in the year, Wind and freeze-thaw composite erosion happened in the transition of autumn to winter and winter to spring, Water erosion mainly occurred in summer, and accompanied by wind erosion, Meanwhile, wind and freeze-thaw erosion products were all carried away by runoff. The results can provide theoretical basis for the measures selection of composite erosion control.

Key words: Pisha sandstone area, composite erosion, water erosion critical, wind erosion critical, freeze-thaw erosion critical, influencing factors
Topographic evolution of mountain belts controlled by rheology and surface process efficiency
Authors: Wolf Sebastian G. , Huismans Ritske S. , Braun Jean , Yuan Xiaoping
Published: March 2020

It has been a long-standing problem how mountain belts gain and loose topography during their tectonically active growth and inactive decay phase. It is widely recognized that mountain belt topography is generated by crustal shortening, and lowered by river bedrock erosion, linking climate to tectonics. However, it remains enigmatic how to reconcile high erosion rates in active orogens as observed in Taiwan or New Zealand, with long term survival of topography for 100s of Myrs as observed for example in the Uralides and Appalachians. Here we use for the first time a tight coupling between a landscape evolution model (FastScape) with an upper mantle scale tectonic (thermo-mechanical) model to investigate the different stages of mountain belt growth and decay. Using two end-member models, we demonstrate that growing orogens with high erosive power remain small (<200 km), reach steady state between tectonic in- and erosional material eff-flux, and are characterized by transverse valleys. Contrarily, mountain belts with medium to low erosive power will not reach growth steady state, grow wide, and are characterized by longitudinal rivers deflected by active thrusting. However, during growth both types of orogens reach the same height, controlled by rheology and independent of surface process efficiency. Erosional efficiency controls orogenic decay, which is counteracted by regional isostatic rebound. Rheological control of mountain height implies that there is a natural upper limit for the steepness index of rivers on Earth. To compare model results to various natural examples, we quantify the degree of longitudinal flow of modeled rivers with river “longitudinality” in several active or recently active orogens on Earth. Application of the river “longitudinality index” gives information whether (parts of) an orogen is or was at steady state during orogenic growth.
Vein-plus-wall rock melting model for the origin of Early Paleozoic alkali diabases in South Qinling Belt, Central China
Authors: Zhang Fangyi , Lai Shaocong
Published: March 2020

Early Paleozoic mafic dykes are widespread in South Qinling Belt, central China. In this study, we present new major element, trace element, zircon U–Pb age and Sr–Nd–Hf isotopic results of Early Paleozoic diabases dykes in the South Qinling Belt to explore nature of the mantle source. The South Qinling Belt diabases have low SiO2 (42.1–49.5 wt%) high TiO2 (2.89–5.17 wt%), variable MgO (4.0–9.4 wt%) contents. In primitive mantle normalized multielement diagrams, all samples are strongly enriched in the majority of incompatible trace elements but systematic depletion in Rb, K, Pb, Zr and Hf. The negative K and Rb anomaly together with high TiO2 and high Na2O/K2O character suggest magma was derived from a source rich in amphibole. Partial melting modelling indicate 20–36% partial melting of amphibole-clinopyroxene-phlogopite veins with subsequent dissolution of ~30% orthopyroxene from the wall-rock peridotite within spinel stability field can produce the observed compositions of diabases. Additionally, South Qinling Belt diabases are characterized by moderately depleted Nd (εNd(t)= +2.2 to 3.3) and Hf (εHf(t)= +6.2 to 7.2) isotopic compositions without pronounced isotope decoupling, indicating mantle metasomatism occurred shortly prior to Early Paleozoic magmatism. It is proposed that low-degree silicate melts released from asthenosphere infiltrated and solidified within lithospheric mantle, forming non-peridotitic lithologies rich in amphibole clinopyroxene and phlogopite. Subsequent lithosphere extension caused the melting of the most easily fusible material in the lithosphere, which gave rise to the Early Paleozoic alkaline magmatism in South Qinling.
Multi-event analysis of SAPS Wave Structures observed by the SuperDARN Hokkaido Pair of radars
Authors: Nishitani Nozomu , Hori Tomoaki , Teramoto Mariko
Published: March 2020

The SuperDARN Hokkaido Pair (HOP) of radars data with special operation modes are used to study the wavy variations of plasma flow embedded in larger-scale, fast flow structures at subauroral latitudes (SAPS). Because of the limited number of examples studied so far, their generation mechanism is not fully understood yet. In this paper we focus mainly on the events on Sep 08, 2017 and Aug. 26, 2018. Both events occurred near the peak of large geomagnetic storms. These events were registered by the SuperDARN radars with higher temporal resolution (3 and 12 seconds respectively) camping beams. Using both camping beam data and 2-dimensional data (with 1 to 2 min temporal resolution) enable us to examine the period, wavelength and propagation speed of these wave structures. In addition, using the data with the new fitting algorithm (fitacf Ver. 3) we have more extended coverage of the echo regions. We notice that  both events were observed during geomagnetic storms (minimum Dst: -124 nT and -174 nT) and the wave structures have limited spatial extent in magnetic local time. On the other hand, there are several differences between these events such as period, propagation speed and geomagnetic latitude. Their possible generation mechanisms will be discussed.
Response of Rice Ecological Indicators to Water Consumption Based on Multi-source Data in Irrigation District Scale
Authors: Yang Junming , Yao Yunjun , Shang Ke , Guo Xiaozheng , Bei Xiangyi , Chen Xiaowei , Jiang Haiying
Published: March 2020

The study of law of crop water consumption in small scale such as irrigation area requires remote sensing image data with high spatial and temporal resolution, however, remote sensing images that possess both high temporal and spatial resolution cannot be obtained for technical reasons. To solve the problem, this paper present a multisource remote sensing data spatial and temporal reflectance fusion method based on fuzzy C clustering model (FCMSTRFM) and multisource Vegetation index (VI) data spatial and temporal fusion model (VISTFM), the Landsat8 OLI and MOD09GA data are combined to generate high spatial and temporal resolution reflectance data and the landsat8 OLI, MOD09GA and MOD13Q1 data are combined to generate high spatial and temporal resolution normalized vegetation index (NDVI) and enhanced vegetation index (EVI) data.

The rice area is mapped by spectral correlation similarity (SCS) between standard series EVI curve that based the EVI generated by VISTFM and average value of each EVI class that generated by classing Multiphase EVI into several class, the extraction results are verified by two methods: ground sample and Google Earth image. high spatial and temporal resolution Leaf area index (LAI) that covered the mainly rice growth and development stages is generated by higher precision method between artificial neural network and equation fitting that establish the relationship between NDVI, EVI and LAI. The yield of rice in the spatial scale is generated by establishing the relationship between yield and LAI of the mainly growth and development stages that has the maximum correlation with yield. Daily high spatial resolution evapotranspiration is generated by using multisource remote sensing data spatial and temporal reflectance fusion method to fusion the MODIS-like scale and Landsat-like scale evapotranspiration that generated by The Surface Energy Balance Algorithm for Land (SEBAL). Based on the data, the evapotranspiration, LAI and yield of rice, obtained by remote sensing methods, rice water growth function is established by Jensen, Blank, Stewart and Singh model.
Atmospheric blocking modulates the odds of heavy precipitation over Pakistan
Authors: Sadaf Nabeela , Lin Yanluan , Dong Wenhao
Published: March 2020

Floods or wet spells have increased over Pakistan in recent years, however a long-term classification of large-scale and synoptic-scale configuration for these events has been lacking. In this study, a total of 53 wet spells during the period of 1951-2015 over the core monsoon domain of Pakistan are identified. Based on daily geopotential height fields from NCEP/NCAR re-analysis, the dominant synoptic-scale systems, displaying distinct low-level circulation and moisture transport, are found during these wet spells over Pakistan. They are categorized as trough with low pressure system (LPS, 30 cases), trough without LPS (19 cases), and LPS only (4 cases) wet spells. Without the accompanying LPS over India, the trough tends to be deep and intrudes to south Pakistan with moisture transport mainly from Arabian Sea. In contrast, the trough is relatively shallow and interacts with presence of the LPS to steer moisture from the Bay of Bengal towards Pakistan. We found that subtropical trough associated with the blocking ridge over west Asia is an essential ingredient of wet spells over Pakistan. The patterns observed from wet spells over Pakistan are different from wet spells over the core monsoon domain of India, which is mainly dominated by LPS. The ridge development and blocking over Siberia is a precursor to wet spells over Pakistan and provides guidance for prediction.

 
Soil Water Content Variation Regression Analysis Using Hyperspectral Camera in Weathered Granite Soils
Authors: Lim Hwan-hui , Lee Seung-Rae , Cheon Enok , Lee Deukhwan , Lee Seungmin
Published: March 2020

Soil water content is one of the most common physical parameters that cause landslides or debris flow. Therefore, it is of very importance to determine or predict the water content variation due to infiltration of rainfall quickly and non-destructively. This study investigates the hyperspectral informations in the visible near-infrared regions (VNIR, 400nm~1000nm) of different samples of granite soils possessing varying water contents. Totally 162 granite samples were taken from 3 mountain areas. A Partial Least Squares Regression (PLSR) analysis was applied to develop calibration models and prediction models.  In the water content variation prediction model, the Area of ​​Reflectance(Near-infrared, NIR) parameter was the most suitable parameter to determine the water content. The results demonstrate that the hyperspectral camera combined with the PLSR model can be a useful and non-destructive tool for the determination of soil water content variation in the weathered granite soils that could be applied to the evaluation of possible instable area in a mountain site.
Lake-atmospheric Interaction and its Impact on the Local Precipitation over Nam co region
Authors: yang xianyu
Published: March 2020

Nam Co Lake is the third largest salt lake in China. Nam Co Lake is a typical inland salt lake and a typical representative area of the complex topography of the Tibetan Plateau. In this study, the effects of Nam Co Lake on the short-term climate in the lake area are analyzed using the Weather Research and Forecasting (WRF) model in conjunction with field observation data for the Nam Co Lake area through a control experiment on the Nam Co Lake area and a sensitivity experiment on the same area without the presence of Nam Co Lake. Moreover, a backward water vapor transfer model is also employed to investigate the contribution of water vapor evaporation (transpiration) from this typical plateau lake and various types of surfaces to local precipitation. The following conclusions are derived: (1) After the removal of the lake, the sensible heat in the original lake area increases, whereas the latent heat decreases. The sum of the sensible and latent heat in the lake area simulated with and without the presence of the lake is 187.6 and 116.7 W·m-2, respectively. (2)After the removal of the lake, precipitation in the central Nam Co Lake area increases significantly, generally by more than 20–30 mm. The presence of Nam Co Lake effectively reduces the height of the ABL over the lake during the day. (3) Approximately 76.93% of the total precipitation in the Nam Co Lake area is contributed by external water vapor sources. Evapotranspiration from grassland surfaces is the secondary water vapor source for precipitation in the study area and 18.34% of the total precipitation is contributed by this source. Approximately 2.46% of the total precipitation in the lake area is contributed by evaporation from Nam Co Lake.
Effects of non-reflection events and stationery source locations on virtual seismic reflection images
Authors: Kim Ki , Song Young-Seok , Byun Joongmoo
Published: March 2020

To notice key obstacles and suggest effective processing methods for virtual reflection images, numerical modeling was performed by the 2-D finite difference method with time and space intervals of 0.2 ms and 1.25 m, respectively. Vertical sources of the Ricker wavelet with a main frequency of 20 Hz were assumed to be detonated independently at five buried locations with intervals of 500 m. Vertical components of the particle velocity were computed at 99 receivers at 10 m depth with intervals of 20 m. Synthetic data show that maximum amplitudes of reflection signals are less than 2% of those of direct Rayleigh waves on an average. This indicates that the non-reflection events should be attenuated as much as possible before correlating traces to compute virtual seismic data. For attenuating both direct and diffracted Rayleigh waves in the synthetic data, a median filter with a time window of a 0.1-s length was effective. Because stationery-phase source locations for virtual reflections concentrate near receiver locations, only common midpoint gathers close to the sources should be used for good virtual stack images.
The time-varying characteristics in tidal duration asymmetry
Authors: Wenyun Guo , Dehai Song , Leicheng Guo , Jianzhong Ge , Pingxing Ding , Xiaohua Wang
Published: March 2020

Tides always behaves different rising and falling durations, which can mostly attribute to the shallow-water effect and interactions among tidal constituents. The duration asymmetry may lead to an inequality in flood/ebb tidal current magnitudes, affecting the net sediment transport. Tidal duration asymmetry has time-dependent characteristics. We deducted a general framework for identifying the time-variability in tidal duration asymmetry. The application to the global tides showed that the fortnightly variability in tidal asymmetry is universal and that duration asymmetry can be stronger during neap tide than during spring tide. Then the framework is applied to the tides in the Changjiang Estuary. Prominent seasonal variation in tidal asymmetry is revealed, mainly relate to the river-tide interaction. Application to the tides in the Yangshan Harbor sea area revealed that the local-scale tidal asymmetry can be changed strongly by a large coastal engineering.
Validation and correction of sea surface salinity retrieval from SMAP
Authors: Qin Sisi
Published: March 2020

In this study, Sea Surface Salinity (SSS) Level 3 (L3) daily product derived from Soil Moisture Active Passive (SMAP) during the year 2016, was validated and compared with SSS daily products derived from Soil Moisture and Ocean Salinity (SMOS) and in-situ measurements. Generally, the Root Mean Square Error (RMSE) of the daily SSS products is larger along the coastal areas and at high latitudes and is smaller in the tropical regions and open oceans. Comparisons between the two types of daily satellite SSS product revealed that the RMSE was higher in the daily SMOS product than in the SMAP, whereas the bias of the daily SMOS was observed to be less than that of the SMAP when compared with Argo floats data. In addition, the latitude-dependent bias and RMSE of the SMAP SSS were found to be primarily influenced by the precipitation and the Sea Surface Temperature (SST).Then, aregression analysis method which has adopted the precipitation and SST data was used to correct the larger bias of the daily SMAP product. It was confirmed that the corrected daily SMAP product could be used for assimilation in high-resolution forecast models, due to the fact that it was demonstrated to be unbiased and much closer to the in-situ measurements than the original uncorrected SMAP product.
The observational evidence of electron mirror mode
Authors: Yao Shutao , Shi Quanqi , Yao Zhonghua , Guo Ruilong , Zong Qiugang , Wang Xiaogang , Alex Degeling , Rae Jonathan , Russell Christopher , Tian Anmin , Zhang Hui , Hu Hongqiao , Liu Ji , Liu Han , Li Bing , Giles Baebara
Published: March 2020

The mirror modes are fundamental process in space, and play important roles in solar physics, planetary, interplanetary, astrophysical and laboratory plasmas over the past half century. Although theoretical studies and numerical simulations further revealed their kinetic effects, they are generally regarded as magnetohydrodynamics (MHD) scale process. However, if the electron distribution is anisotropic, the electrons could become unstable and excite kinetic scale mirror modes to remove the free energy. This instability was presented for more than thirty years, but so far few unambiguous observational evidence has been found. In this study, we provide high-resolution Magnetospheric Multiscale (MMS) observations of electron mirror mode structures. These structures: (1) are train-like features similar to the MHD-scale mirror-mode; (2) are anti-correlation between electron and magnetic pressure; (3) satisfy electron trapping conditions and theoretical excitation of the mirror modes; (4) are “frozen” in the plasma flow frame. They were observed during the Corotating Interaction Region events (CIRs) near the Earth’s foreshock and its downstream turbulence, and could involve with the interaction between Earth’s magnetosphere and solar wind.
Tall tower eddy covariance as a tool for evaluating climate change mitigation in Vienna, Austria
Authors: Matthews Bradley , Schume Helmut
Published: March 2020

The need for climate action in cities is becoming more and more critical. As such, systems that quantify local greenhouse gas (GHG) emissions to evaluate mitigation measures are growing in importance and are set to undergo increasing levels of scrutiny. Within the CarboWien project, the University of Natural Resources and Life Sciences, Vienna, the Environment Agency Austria and the telecommunications company A1 Telekom Austria AG are currently collaborating to investigate the potential of a tall tower eddy covariance station to support carbon dioxide (CO2) emissions monitoring in Vienna. Due to the tall tower approach (144 m measurement height) the measured turbulent fluxes are representative of net emissions from much of the city area. If maintained in the near- to medium‑term, this facility could provide an additional, independent instrument with which local climate change action can be continuously evaluated.

This conference contribution will present results from the measurement campaign so far (2018-2019). In addition to discussing the early-indicator function of these data and the scope for improving emissions inventories, the presentation will demonstrate how these measurements can be directly used to evaluate local mitigation measures. In particular, analyses of the 30-minute fluxes against local activity/proxy data will show how the performance of measures seeking to reduce CO2 emissions from road traffic and space heating can be inferred.
Chemical composition and volatility distribution of SOA formed by ozonolysis of β-caryophyllene between 213-313 K
Authors: Gao Linyu , Vallon Magdalena , Song Junwei , Huang Wei , Leisner Thomas , Saathoof Harald
Published: March 2020

β-Caryophyllene is the most common and abundant of the sesquiterpenes emitted into the atmosphere (Duhl et al., 2008). Although sesquiterpene emission rates were estimated to be only 9–16% of the total terpene emissions (Duhl et al., 2008), they are more reactive and larger in size than monoterpenes. Consequently, their aerosol mass yields are large and result in a significant contribution to the SOA budget in the atmosphere (Tasoglou and Pandis, 2015). Therefore, we studied the composition of both gas and particle phases as well as phase partitioning of SOA from ozonolysis of β-caryophyllene in presence and absence of NOx at five temperatures (213 K, 243 K, 273 K, 298 and 313 K) in the AIDA aerosol simulation chamber. This work focusses on the characterization of the SOA by mass spectrometry employing a FIGAERO-HR-TOF-CIMS operated with iodide ions and a HR-TOF-AMS (both Aerodyne Inc.). Particle phase analysis shows three groups of compound masses with m/z 240-400, (C5-16),  (m/z 400-560, (C20-34), and m/z 560-680, (C35-40) classified as monomers, dimers, and trimers, respectively.  Trimeric compounds were observed preferentially in SOA formed at higher temperatures (273 K, 298 K, 313 K), while only monomeric and dimeric compounds were detected at lower temperatures (243 K and 213 K). Interestingly, dimeric compounds, including CxHyOz and CxHyOzN1, contribute more to SOA mass for the lower temperatures. Comparing volatility distributions for the five different temperatures using the Volatility Basis Set (VBS) and thermal desorption information from FIGAERO-CIMS (298-473 K) we find more compounds with lower volatility for lower SOA formation temperatures. This contribution will discuss the volatility distributions obtained with and without NOx as well as the abundance of specific reaction products.
The North Atlantic Eastern Boundary: Observations from Moorings at Goban Spur 2016-2019
Authors: Moritz Martin , Jochumsen Kerstin , Kieke Dagmar , Klein Birgit , Klein Holger , Köllner Manuel , Rhein Monika
Published: March 2020

Since 2016 a moored observatory is operated at the eastern extension of the “North Atlantic Changes (NOAC)” array at 47°/48°N. This observatory is installed across the shelf break at Goban Spur and consists of two deep-sea moorings that are separated by about 60 km.  

The aim of this ongoing monitoring program is to quantify the variability and trends in the properties and transport rates of water masses that are advected northwards along the North Atlantic Eastern Boundary and modify the adjacent regions, i.e. the Northwest European Shelf, North Sea, Nordic Seas and Arctic Ocean. Furthermore, the continuous long term time series are essential for a thorough understanding of the circulation system in the eastern North Atlantic and the underlying physical mechanisms that govern its variability.

Here, we present results of the analysis of temperature, salinity and current velocity time series from 2016 to 2019. These provide a descriptive view of the complex current structure and variability of water masses on daily to intra- and inter-annual time scales.

The most pronounced signal in the variability of temperature and salinity is caused by the presence of Mediterranean Outflow Water located at about 1000 m depth. During the observation period we find significant positive trends in temperature and salinity in the depth range of 500 to 1500 m. The velocity measurements of the onshore mooring show a northeastward directed mean flow following the topography with along-slope variations, while the flow at the offshore mooring position is more unstable with predominantly cross-slope variations. 

The combination of our observations with float and altimeter data indicates that the presence of eddies and the interaction with the topography seems to play a crucial role for setting the variability of the flow in this region.

Finally, we present an approach to evaluate the volume fluxes at the eastern boundary that will add toward an integrated estimate of the strength of the Atlantic Meridional Overturning Circulation at 47°/48°N.
Archaeointensity data from Japan: current status and future perspectives
Authors: Hatakeyama Tadahiro , Tema Evdokia , Matsumoto Naoko
Published: March 2020

Japan is a country with very rich cultural heritage and with many archaeological sites that can offer precious information about the geomagnetic field secular variation in the past. However, even though archaeomagnetic research in Japan started more than 60 years ago, with numerous studies focused on archaeodirection determinations of in situ archaeological structures, the available up to now archaeointensity data are still scarce. Most of the absolute intensity records come from archaeomagnetic studies carried in 60’s, 70’s and 80’s, mainly obtained with the original Thellier-Thellier method and/or its modifications. In none of these data, cooling rate and anisotropy corrections were applied. During the last 20 years, only two more archaeointensity studies have been published, applying the Tsunakawa-Shaw palaeointensity method on baked clays from Japanese kilns. This current status of archaeointensity studies in Japan makes evident the need of new high-quality reference data in order to reconstruct the geomagnetic intensity secular variation path in Japan. In this perspective, in the frame of the “Be-Archaeo” MSCA-RISE project, we have collected a total of 56 fragments of archaeological artifacts from the archaeological sites of Sada Higashizuka, Sada Nishizuka, Tatezaka, Tenguyama, Tatetskuki and Nima Ohtsuka, situated at the Okayama prefecture. The baked clays studied belong to ancient coffins, haniwa artifacts and pottery and their ages range from 100 AD to 675 AD. Preliminary rock magnetic and archaeomagnetic analysis including magnetic susceptibility, Q-ratio, isothermal remanent magnetization (IRM) curves, thermal demagnetization of a composite IRM component as well as stepwise thermal and alternating field (AF) demagnetizations were performed to investigate the magnetic mineralogy of the samples and their suitability for archaeointensity experiments. The results show the presence of a magnetic mineral with Curie temperature ranging from 480 to 560 oC, most probably magnetite and/or Ti-magnetite. IRM curves and AF demagnetization suggest also the presence of a high coercivity component in some samples, as saturation is not reached at 1 T and samples are not completely demagnetized at 180 mT. Demagnetization diagrams reveal a stable single component of magnetization for most of the samples. However, some samples demonstrate disturbed Zijderveld diagrams and/or two components of magnetization; no correlation between the quality of the results and the material studied (pottery, haniwa or coffin fragments) was found. These preliminary results were used to select promising samples for archaeointensity experiments, aiming to obtain new high-quality archaeointensity records for the Late Yayoi and Kofun periods.
Numerical Simulations for the Warm Rain Properties during RICO with a Newly Developed Triple-moment Warm Cloud Scheme
Authors: Deng Wei
Published: March 2020

    Double-moment schemes with a constant shape parameter cannot describe the condensation process and the collision coalescence processes properly. Evolutions of cloud droplet spectra and raindrop spectra simulated with different current bulk microphysical schemes also showed big differences. The newly developed triple-moment scheme (IAP-LACS scheme) considered the variation of the shape parameters of water drop distributions by means of the radar reflectivities of cloud droplets and raindrops, respectively, during the condensation process and collision-coalescence processes. In order to evaluate the performance of our new scheme, we use large-eddy simulation in WRF to research the precipitation formation in Rain in Cumulus over the Ocean (RICO) observation study with new triple-moment warm cloud scheme. This paper will show the simulation results for the microphysical characteristic, specical for the evolution of warm raindrop size distribution in comparison with aircarft measurement. Our simulations show that our new triple-moment scheme can grasp the main characteristic of raindrop size distribution as observation and there must be difference exsiting in simulation results between new scheme and other microphysical bulk schemes.
Evolution of Climate Growth Period in Chinese Based on Coordinated Regional Downscaling Experiment
Authors: Yang Huaizhi , Li Pengcheng , Zhao Xinyi
Published: March 2020

Based on the historical measured temperature data (1971 ~ 2010) and the output of coordinated regional downscaling experiment (CORDEX) East Asia, including the climate prediction based on RCP4.5 and RCP8.5, the authors get the evolution pattern of climatic growth period in historical period and future scenarios.. The results show : (1) in the 40 years from 1971 to 2010, the duration of the climatic growth period in most regions of China increased slightly, and the effect of the advance of the start date of the growth period on the climatic growth period was dominant. (2)In RCP4.5, the change of the start date of the climatic growth period is mainly in East China, Central China, Northwestern South China, Northern South China and the Qinghai-Tibet Plateau, while the change of the end date is mainly in the central, southern and eastern parts of the Tibetan Plateau and the mountainous regions of Xinjiang. (3)In RCP8.5, days of change of start date  increase significantly. The duration of the climatic growth season in southern South China has remained unchanged, and the rest of the region has been extended for more than 20 days. (4) Although the number of meteorological stations in the Qinghai-Tibet Plateau is relatively small, the terrain is more complex, and the accuracy of the calculation results is affected, the northern Qinghai-Tibet Plateau is the most sensitive to global changes in both historical periods and future scenarios.
Horizontal moisture transport shapes the regional moistening patterns in the Arctic
Authors: Nygård Tiina , Naakka Tuomas , Vihma Timo
Published: March 2020

The Arctic has experienced regionally and seasonally variable moistening of the atmosphere during the recent decades. Compared to the accompanying amplified warming and dramatic sea ice decline, the moistening has so far remained less studied.

We address the regional and seasonal trends in the horizontal moisture transport in the Arctic during the last four decades, in 1979–2018, based on data of ERA5 reanalysis of European Centre for Medium-Range Weather Forecasts. We show that regional trends in moisture transport are large and mainly driven by changes in atmospheric circulation. We demonstrate that the regional moistening patterns in the Arctic during the last four decades have dominantly been shaped by these strong trends in horizontal moisture transport. Changes in local evaporation in the Arctic have only had a minor role in shaping the moistening patterns. We show that increasing trends in evaporation have been restricted to the vicinity of sea-ice margin over a limited period during the local sea-ice decline, and this step-wise increase has been followed by negative trends in evaporation in open sea, due to suppressing effect of horizontal moisture transport.

Both evaporation and the horizontal moisture transport have been affected by the diminishing sea-ice cover during the cold seasons from autumn to spring, and their trends have been dependent on the flow direction. We summarize the current understanding and the new results of flow-dependency of the trends in moisture transport and evaporation near the sea-ice margin, and the cloud response to those.

For the first time, we provide a detailed picture of both the drastic regional changes in the moisture transport within the Arctic and changes in local evaporation, and demonstrate large impacts of these changes on the climate of the Arctic. We suggest that also in the future, moisture and cloud distributions in the Arctic are expected to respond to changes in atmospheric pressure patterns; circulation and moisture transport will also control where and when efficient surface evaporation can occur.
The Bigger The Better? - Updates on the Statistical Limits of Nano-Palaeomagnetic Works and (sub)millimeter Samples
Authors: Berndt Thomas , Muxworthy Adrian , Fabian Karl , Chang Liao
Published: March 2020

A recent trend in paleomagnetism is the study of samples of ever decreasing sizes, going down to (sub)millimeter scales and even microscopic scales (“nanopaleomagnetism”). These include studies of single-silicate-crystals, microscopic magnetic imaging of the cloudy zones in Iron meteorites, and recently even the determination of individual magnetic remanence carriers. As single-crystal and nanopalaeomagnetic methods are getting more adopted, it is getting increasingly important to assess the statistical reliability with which such small samples can record remanences from a physical perspective. We previously proposed a benchmark to assess small-scale samples of randomly oriented non-interacting single-domain (SD) particles and found that in most cases, the number of magnetic particles a sample must contain lies in the order of tens to hundreds of millions – or equivalently NRM strengths of the order of 10-12 Am2. In this talk, we present how this benchmark can be used as a simple yet indispensable tool to assess whether or not (sub)millimeter-size and nanopalaeomagnetic samples are able to statistically reliably record palaeomagnetic fields. Moreover, this talk will provide an outlook into future limitations but also opportunities of the statistical physics nature of microscopic magnetic particle systems. It will explore if multi-domain particles should ever be considered statistically reliable recorders, how interactions in SD particle clusters might affect statistical reliability, and will review the various challenges that Iron meteorites pose as a remanence recorder.
An evaluation of East Asian Extratropical cyclones in CMIP5 models and their response to greenhouse warming
Authors: Lee Jaeyeon , Hwang Jaeyoung , Son Seok-Woo , Gyakum John
Published: March 2020

The extratropical cyclones (ETCs) over East Asia and their possible future changes are evaluated using the Coupled Model Intercomparison Project phase 5 (CMIP5) models. The East Asian ETCs are identified using an automated tracking algorithm applied to the 850-hPa relative vorticity field for both reference data (ERA-Interim reanalysis data) and model data. The CMIP5 models well capture the spatial distribution of East Asian ETC properties, although significant biases are present around the high-topography regions. Based on the individual model biases, Best 5 models are selected and used for examining the future changes of East Asian ETCs. In future climate, Best 5 shows declined cyclogenesis in the leeward side of the Tibetan Plateau, which is partly responsible for the decreased ETC frequency over the western North Pacific. The intensity of individual ETCs is also projected to decrease in a warm climate. These changes could be attributed to the combined effect of increased static stability and decreased vertical wind shear in East Asia, which means reduced local baroclinicity. It is also found that CMIP6 models have smaller bias than Best 5 CMIP5 models, indicating that the result documented in this study may change in quantity when newly-available CMIP6 models are utilized.
Spatiotemporal vegetation variations and projections driven by atmosphere-ocean oscillations at multiple time scales: a case study in Gansu, China
Authors: He Qing , Chun Kwok Pan , Pan Xicai , Chen Liang , Fan Pinyu
Published: March 2020

Vegetation is an integrated regional indicator of environmental changes related to soil, water and climate. For investigating climate change impacts on ecosystems, the transition zones of vegetations are natural hotspots of historical variations. As a transition zone between humid and arid climates in the northwest region of China, the terrestrial ecosystems of Gansu vary from dense vegetation landscapes in southeast to deserts in northwest. Exploring spatiotemporal vegetation responses to climate variations over Gansu has a great significance to project shifting northwest China vegetation patterns which affect regional water and food security. In this study, the spatiotemporal variations of vegetation were characterised by using the Normalized Difference Vegetation Index (NDVI). Between 2001 and 2019, there was a significant increase of the vegetation cover in almost the whole Gansu, and the increasing trend (around 0.015) was more predominant in the southeast part. Over the whole Gansu, especially at the southeast region, the Webster and Yang Monsoon (WYM) and the North Pacific El Nino oscillation (NP) had significant positive relationships with the extent of vegetation coverage at intra-annual and decadal scales respectively. Although the Central Pacific El Nino oscillation (CP) is only a statistically significant variable for some spotty locations of Gansu, it is negatively related to the vegetation variation over the northwest Gansu at an interannual scale. Based on the above relationships between vegetation and climate variables at different temporal scales, the future vegetation conditions of Gansu were projected based on the Beijing Normal University Earth System Model (BNU-ESM) outputs for the RCP4.5 and RCP8.5 scenarios. In a short term (the 2020s), vegetations in Gansu would increase because of the warmer temperatures along with possible increasing snowmelt water. However, for longer terms (the 2050s and the 2080s), the regional vegetation would significantly decline for both RCP4.5 and RCP8.5 scenarios, due to the depletion of snowmelt water sources resulted from the continuously increasing temperature and less snow accumulation in the region. The vegetation projections revealed the future desertification risk in Gansu. These results have important implications to water and food security in the vegetation transition zones of northwest China, which is a key region of the One Belt One Road initiative, connecting semi-arid regions of central Asian nations.
Modelling the Microbial Carbon Pump in a changing ocean: current state and future directions
Authors: Polimene Luca , Sailley Sevrine , Clark Darren , Kimmance Susan
Published: March 2020

Circa 624 gigatons of carbon are locked in the ocean as dissolved organic matter (DOM), an amount comparable with the entire CO2 content of the extant atmosphere. This DOM is operationally defined as refractory, meaning that it is resistant to bacterial degradation and persists in the ocean for millennia. Refractory DOM is considered primarily a residual product of heterotrophic bacterial activity after the bacterial consumption of more labile (i.e. easily degradable) DOM produced by marine autotrophs through photosynthesis. The process through which bacteria form refractory-DOM is termed the ‘Microbial Carbon Pump’ (MCP). Abiotic degradation (e.g. photo-degradation) is thought to balance refractory DOM production, thus maintaining its current pool in steady state. However, recent studies suggest that changes in surface ocean inorganic nutrient availability, due to climate change related increases in thermal stratification, could modify MCP activity, increasing refractory-DOM production with respect to its consumption. Marine bacteria thus have the potential to mitigate increases in atmospheric CO2 by shunting more photosynthesised carbon into refractory-DOM. This hypothesis can only be tested by including the MCP in numerical models used for climate prediction. However, the lack of mechanistic understanding of the process (due, in turn, to the lack of experimental data) has hitherto prevented the development of adequate model formulations. In this talk, I will discuss the potential (and limitations) of existing process models to simulate (at least partially) the MCP and highlight future research directions (and related challenges) to develop new model formulations describing this process.
Inverse cascade of kinetic energy in two-dimensional β-Plane magnetohydrodynamic turbulence
Authors: Zinyakov Timofey , Petrosyan Arakel
Published: March 2020

Numerical studies of two-dimensional β-plane homogeneous magnetohydrodynamic turbulence are presented. The study of the fundamental properties of such turbulence allows understanding the evolution of various astrophysical objects from the Sun and stars to planetary systems, galaxies, and galaxy clusters. Energy spectra and cascade process in two-dimensional β-plane MHD are studied.

In this work the equations of two-dimensional magnetohydrodynamics with the Coriolis force in the β-plane approximation are used for the qualitative analysis and numerical simulation of processes in plasma astrophysics. The equations are solved on a square box of edge size 2π with periodic boundary conditions applying a the pseudospectral method using the 2/3 rule for dealiasing. The results of numerical simulation of two-dimensional β-plane MHD turbulence with a spatial resolution of 1024 × 1024 and 4096 × 4096 with different Rossby parameters β and different Reynolds numbers are presented.

It is found that only unsteady zonal flows with complex temporal dynamics are formed in two-dimensional β-plane magnetohydrodynamic turbulence. It is shown that flow nonstationarity is due to the appearance of isotropic magnetic islands caused by the Lorentz force in the system. The formation of Iroshnikov–Kraichnan spectrum is shown in the early stages of evolution of two-dimensional β-plane magnetohydrodynamic turbulence. The self-similarity of the decay of Iroshnikov–Kraichnan spectrum is studied. On long time scale violation of self-similarity of the decay and formation of Kolmogorov spectrum is discovered. The inverse cascade of kinetic energy, which is characteristic of the detected Kolmogorov spectrum, provides the formation of zonal flows.

This work was supported by the Russian Foundation for Basic Research (project no. 19-02-00016).