bluuebunny/crossref_metadata_2025 huggingface dataset:
Projected changes of temperature extremes over Southeast Asia under 1.5 and 2 degrees global warming
Authors: Ge Fei , Zhu Shoupeng , Zhi Xiefei , Sielmann Frank , Fraedrich Klaus
Published: March 2020

Projected changes in temperature extremes at 1.5°C and 2°C global warming levels (GWLs) have been evaluated for Southeast Asia (SEA) based on temperature extreme indices from ETCCDI using the latest available CORDEX simulations. Results show that the temperature indices significant increase across Indochina Peninsula and Maritime Continent at 1.5°C and 2°C GWLs except for the decreasing daily temperature range (DTR) in the dry season. The most pronounced increases of summer days (SU) are projected in Sulawesi with the percentage magnitude of 31.7% and 19.7% (47.2% and 31.3%) at the 1.5°C (2°C) GWL for wet and dry seasons, respectively, while tropical nights (TR) increase significantly over Sumatra and Sulawesi. Robust differences of temperature extremes can be found over the SEA in both wet and dry seasons for the additional global warming of 0.5°C. The temperature extremes under the global warming of 1.5°C and 2°C levels and their differences primarily concentrate on the main islands in the densely populated coastal regions, suggesting more conspicuous impacts on the human system in the developing countries over the SEA.
Sedimentary responses to the climate changes in the Bay of Bengal since the last glaciation
Authors: Li Jingrui , Shi Xuefa
Published: March 2020

A sedimentary multi-index comprehensive study on a gravity core collected from the central Bay of Bengal (BoB) was presented with an attempt to understand the sedimentary processes and their responses to climate changes since the last glaciation. The sea level is suggested to be responsible for significant distinction of the terrigenous input between the last glaciation and the Holocene period through the depositional center transition in the BoB at the glacial-interglacial scale. The monsoon controlled terrigenous input at precession-related scales since it showed similar patterns with solar radiation and precipitation before 18 ka. Terrigenous input responses to the climate changes in the north Atlantic Ocean during the last deglaciation and early Holocene suggested at millennial scales. The paleoproductivity in the central BoB was at a roughly equivalent level during the last glaciation and the Holocene period, as indicated by the authigenic element accumulation rates. Different terrestrial nutrient inputs and ocean surface stratifications related to the Indian Summer Monsoon (ISM) were suggested to be responsible for this pattern. This study provides a brief understanding of the sedimentary response to the climate and emphasizes the different roles of the sea level and ISM in the central BoB.
Microplastics intrude into the Tibetan Plateau
Authors: Zhang Yulan , Gao Tanguang
Published: March 2020

Microplastics have been widely found in the aquatic and terrestrial environments, such as in sea water, sea ice, lake/river water, and sediments. Glaciers also bring an important temporal component to microplastics studies, which can reveal atmospheric deposition in polar or high-altitude environments. However, microplastics accumulating in glaciers or being released from melting glaciers are still sparsely reported, particularly in the Tibetan Plateau (TP), which covers 5 million km2 with an average elevation of >4,000 m a.s.l. (above sea level), and contains a large volume of glaciers in the mid-low latitude regions. Adjacent to human settlements in South Asia, East China, and central Asia, the TP is readily influenced by cross-border air pollution that can affect its vulnerable and pristine environments, among which the cryospheric environments, particularly glaciers, have been drawing increasing attention for their accelerated melting and relevant risks to regional water resources and quality. Recently, microplastics have been detected in glaciers and lake water at different locations on the TP, indicating that they can be transported to the TP. The findings are expected to be significant for narrowing knowledge gaps in connecting transport atmospheric pollutants and cryospheric changes over the TP, and for serving as a valuable and fundamental scientific basis for regional environmental protection and policy-making.
Evaluation of the relationship between daily extreme precipitation and temperature over Eastern China
Authors: Wang Rui
Published: March 2020

    In this work, the relationship between daily extreme precipitation and temperature is investigated by using rain gauge precipitation data and corresponding the Integrated Global Radiosonde Archive over eastern China during 1998-2012. Eventually, 14 stations are selected to explore the relationship in eastern China (MEC) and southeastern China (SEC). The result shows that daily extreme precipitation intensity increases approximately 7% when near surface temperature increases 1 °C in MEC and SEC, which generally follows Clausius–Clapeyron (CC) rate (CC rate describes the increasing rate of water vapor with temperature). Moreover, the regression slopes for the logarithmic daily extreme precipitation intensity and near surface temperature range from 3% °C-1 to 9% °C-1 at the selected stations in MEC and SEC. However, extreme precipitation intensity decreases with near surface temperature when the temperature is higher than 25 °C. That is, the increase of extreme precipitation with near surface temperature performances single peak structure in MEC and SEC. The variation of extreme precipitation and near surface dew point temperature shows the similar pattern in MEC and SEC (The transition dew point temperature is also about 25 °C). Therefore, it could be deduced that extreme precipitation intensity does not always increase with climate warming in MEC and SEC. In addition, precipitable water, which corresponds to extreme precipitation event, increases with near surface temperature at CC rate. It is found that the increase rate of precipitable water with temperature is closer to CC rate than that of extreme precipitation.
Monitoring the drought resilience of near-natural peatlands by means of SAR remote sensing
Authors: Huber García Verena , Marzahn Philip , Ludwig Ralf
Published: March 2020

Peatlands have been intensively used for centuries either for peat extraction, agricultural usage or forestry. The related drainage has led to falling water levels, altered microbial activity and the associated greenhouse gas emissions, the shrinkage of the peat layer and an overall degradation of peatland areas causing the disruption of these ecosystems. Lately, some areas have been restored and brought back to a semi-natural state by prohibiting their use and lifting the water table.

To monitor shrinkage and swelling processes of the peat layer, we applied the Persistent Scatterer Interferometry (PSI, Ferretti et al. 2001) to several upland peatlands south of the city of Munich, Germany, for the period 2015-2018. This technique uses time-series of Synthetic Aperture Radar (SAR) satellite images from the Sentinel 1A and 1B platforms, to monitor potential surface deformation caused by swelling and shrinkage of the peat layer due to water content.

The presentation will show the captured seasonal height fluctuations peatland areas are naturally subject to. The overall trend for the observation period shows a subsidence for most investigated peatlands. Furthermore, we could observe a strong negative trend over most study areas throughout the year 2018. This is expectedly related to the extremely dry conditions in 2018 in this part of Europe which caused the peat layer to dry out and to shrink.

The results illustrate how peatlands react to dry periods. The question remains how resilient peatlands are to droughts, particularly when considering that dry periods may occur more often in the future. In consequence, the findings will also be instrumental to assess the climate mitigation potential of rewetted peatlands. By means of PSI it is possible to monitor surface changes over long time frames and assess the long-term vulnerability of natural and restored peatlands to climate change.

The work presented here is part of the KliMoBay project, funded by the Bavarian State Ministry for the Environment and Consumer Protection through the European Regional Development Fund (ERDF).

Ferretti, A.; Prati, C.; Rocca, F. (2001): Permanent scatterers in SAR interferometry. IEEE Trans. Geosci. Remote Sensing 39 (1), S. 8–20.
Building Industry Resilience to Compound Events
Authors: Winter Hugo , Tilloy Alois , Hendry Alistair , joly-Laugel Amelie
Published: March 2020

Key Words: Compound events; Multi-hazards; Industry application; Multivariate extreme value theory.

Abstract:

Resilience of pre-existing and new-build infrastructure to natural hazards is of key interest for many different industries (e.g. energy, water, transport). In most situations, studies analyzing the risk posed by single natural hazards have already been undertaken and relevant protection measures have been implemented. However, when considering the potential impacts of compound events or multi-hazards there can be less confidence in which combinations need to be considered and how to estimate the risks associated to these multi-hazard scenarios. Certain industries (e.g. nuclear) have already undertaken several projects on the occurrence and risks posed by multi-hazards (e.g. ASAMPSA-E, NARSIS), whereas other industries are still trying to understand their risks and which questions need to be posed.

 

The EDF Energy R&D UK Centre are part of an industry scheme funded by NERC called the Environmental Risks for Infrastructure Innovation Programme (ERIIP) which aims to connect academics to industrial organisations and undertake translational research. One of the key topics of further research identified by this group is the topic of compound events and multi-hazards. A recent review of knowledge on multi-hazards was undertaken by the British Geological Survey (BGS) which highlighted the state of knowledge across UK infrastructure owners.

 

This presentation will start by summarizing this review to pull out some key themes for future research in this area. Then, two different ongoing research projects will be outlined which look to address the key themes coming out of the review. One project is attempting to better understand the different multivariate statistical methods that are available for assessing the probability of multi-hazards. The application of the different models outlined in this work will be shown on an example of extreme precipitation and wind speed. The other project aims to better understand the overarching meteorological conditions that can lead to compound flooding at coastal sites around the UK. This focuses less on estimating joint probabilities, but more on producing clear visualisations for end-users.  
Crustal Structure and tectonic attribute Revealed by a Deep Seismic Sounding Profile of Dinghu-Gaoming-Jinwan in the Pearl River Delta
Authors: Ye Xiuwei , Zhang Xiang , Lv Jinshui , Liu Baofeng , Wang Xiaona , Wang LIwei , Lv Zuoyong
Published: March 2020

To find out the crustal structure and  tectonic attribute  of the Pearl river delta and offshore area(PRD), in 2015, the Guangdong Earthquake Agency collaboration with the other unit  carried out a three-dimensional joint onshore-offshore seismic detection  experiment in the PRD.  This paper processed the data of Dinghu-Gaoming-Jinwan L1 line on the west side of PDR. We utilized ray tracing and travel-time simulation  method to obtained a P-wave velocity model of the L1 profile.The study showed: Along the profile, The depth of the Moho gradually decreases from the northwestern inland 30.0km to the southwestern coastal 28.0km. Upheaval  of the Moho is between Dinghu and Gaoming. The low velocity layer in the mid-crustal  is  a heterogeneous continuum. The velocity of low velocity layer NW side is lower than the SE side, especially between Dinghu and Gaoming. The minimum velocity is 6.05km•s-1. The deep Wuchuan-Sihui fault and Guangzhou-Enping fault  may be one of the most important channels for deep material upwelling. It is the continuum upheaval  of the Moho which from Dinghu, Gaoming on the west side of PDR to  Qingyuan, Conghua on the east side of PDR delimited by Wuchuan-Sihui fault and Guangzhou-Enping fault.
Aerosol-forced AMOC changes in CMIP6 historical simulations.
Authors: Menary Matthew , Robson Jon , Allan Richard , Booth Ben , Cassou Christophe , Gastineau Guillaume , Gregory Jonathan , Hodson Dan , Jones Colin , Mignot Juliette , Ringer Mark , Sutton Rowan , Wilcox Laura , Zhang Rong
Published: March 2020

The Atlantic Meridional Overturning Circulation (AMOC) has been, and will continue to be, a key factor in the modulation of climate change both locally and globally. Reliable simulations of its decadal to century-timescale evolution are key to providing skilful predictions of future regional climate, and to understanding the likelihood of a potential AMOC collapse. However, there remains considerable uncertainty even in past AMOC evolution. Here, we show that the multi-model mean AMOC strengthened by approximately 10% to 1985 in new historical simulations for the 6th Coupled Model Inter-comparison Project (CMIP6), contrary to results obtained from CMIP5. The simulated strengthening is due to a stronger anthropogenic aerosol forcing, in particular due to aerosol-cloud interactions. However, comparison with an observed sea surface temperature fingerprint of AMOC evolution during 1850-1985, and the shortwave forcing during 1985-2014, suggest that anthropogenic forcing and the subsequent AMOC response may be overestimated in some CMIP6 models.
Energetic particle flux variations detected at low altitudes by Space Application of Timepix Radiation Monitor (SATRAM)
Authors: Gohl Stefan , Němec František , Bergmann Benedikt , Pospíšil Stanislav
Published: March 2020

The Space Application of Timepix Radiation Monitor (SATRAM) on board the Proba-V satellite of the European Space Agency (ESA) was launched in May 2013 into a sun-synchronous orbit with an altitude of about 820 km. This technology demonstration payload is based on the Timepix technology developed by the CERN-based Medipix2 Collaboration. It is equipped with a 300 um thick silicon sensor with a pixel pitch of 55 um in a 256 x 256 pixel matrix. The device is sensitive to X-rays and all charged particles. A Monte Carlo simulation was conducted to determine the detector response to electrons (0.5–7 MeV) and protons (10–400 MeV) taking into account the shielding of the detector housing and the satellite. With the help of the simulation, a strategy was developed to estimate omnidirectional electron, proton, and ion fluxes around Earth using stopping power, maximum energy deposition per pixel of the particle track, and the shape of the particle tracks in the sensor. Presented are typical overall dose rates as well as fluxes of individual particle species. A superposed epoch analysis is used to analyze variations of particle fluxes related to geomagnetic storms and interplanetary shock arrivals as a function of time and L-shell.
The overlap of aftershock coda waves and forecasting the first hour aftershocks
Authors: Lippiello Eugenio , Petrillo Giuseppe , Godano Cataldo , de Arcangelis Lucilla , Tramelli Anna , Papadimitrou Eleftheria , Karakostas Vassilis
Published: March 2020

We show that short term post-seismic incompleteness can be interpreted in terms of the overlap of aftershock coda waves. We use this information to develop a novel procedure which gives accurate occurrence probabilities of post-seismic strong ground shaking within 30 minutes after the mainshock. This novel approach uses, as only information, the ground velocity recorded at a single station without requiring that signals are transferred and elaborated by operational units. We will also discuss how this information can be implemented in the Epidemic-Type Aftershock Sequence model in order to reproduce statistical features in time and magnitude of recorded aftershocks.

Main references

de Arcangelis L., Godano C. & Lippiello E. (2018) The Overlap of Aftershock Coda Waves and Short-Term Postseismic Forecasting. Journal of Geophysical Research: Solid Earth, 123: 5661-5674,doi:10.1029/2018JB015518

Lippiello E., Petrillo G. , Godano G. , Tramelli A., Papadimitriou E. &, Karakostas V. (2019) Forecasting of the first hour aftershocks by means of the perceived magnitude. Nature Communications , 10, 2953, doi:10.1038/s41467-019-10763-3
Aurora Basin, the weak underbelly of East Antarctica
Authors: Pelle Tyler , Morlighem Mathieu , S. McCormack Felicity
Published: March 2020

Containing ~52 m sea level rise equivalent ice mass (SLRe), the East Antarctic Ice Sheet (EAIS) is a major component of the global sea level budget; yet, uncertainty remains in how this ice sheet will respond to enhanced atmospheric and oceanic thermal forcing through the turn of the century. To address this uncertainty, we model the most dynamic catchments of EAIS out to 2100 using the Ice Sheet System Model. We employ three basal melt rate parameterizations to resolve ice-ocean interactions and force our model with anomalies in both surface mass balance and ocean thermal forcing from both CMIP5 and CMIP6 model output. We find that this sector of EAIS gains approximately 10 mm SLRe by 2100 under high emission scenarios (RCP8.5 and SSP585), and loses mass under low emission scenarios (RCP2.6). All basins within the domain either gain mass or are in near mass balance through the 86-year experimental period, except the Aurora Subglacial Basin. The primary region of mass loss in this basin is located within 50 km upstream of Totten Glacier’s grounding line, which loses up to 6 mm SLRe by 2100. Glacial discharge from Totten is modulated by buttress supplied by a 10 km ice plain, located along the southern-most end of Totten’s grounding line. This ice plain is sensitive to brief changes in ocean temperature and once ungrounded, glacial discharge from Totten accelerates by up to 70% of it present day configuration. In all, we present plausible bounds on the contribution of a large sector of EAIS to global sea level rise out to the end of the century and target Totten as the most vulnerable glacier in this region. In doing so, we reduce uncertainty in century-scale global sea level projections and help steer scientific focus to the most dynamic regions of EAIS.
Comparison of Eulerian bin and Lagrangian particle-based schemes in simulations of Pi Chamber dynamics and microphysics
Authors: Grabowski Wojciech W.
Published: March 2020

This paper discusses a comparison of simulations applying either a traditional Eulerian bin microphysics or a novel particle-based Lagrangian approach to represent CCN activation and cloud droplet growth. The Eulerian microphysics solve the evolution equation for the spectral density function, whereas the Lagrangian approach follows computational particles referred to as super-droplets. Each super-droplet represents a multiplicity of natural droplets that makes the Lagrangian approach computationally feasible. The two schemes apply identical representation of CCN activation and use the same droplet growth equation; these make direct comparison between the two schemes practical. The comparison, the first of its kind, applies an idealized simulation setup motivated by laboratory experiments with the Pi Chamber and previous model simulations of the Pi Chamber dynamics and microphysics. The Pi Chamber laboratory apparatus considers interactions between turbulence, CCN activation, and cloud droplet growth in moist Rayleigh-Bénard convection. Simulated steady-state droplet spectra averaged over the entire chamber are similar, with the mean droplet concentration, mean radius, and spectral width close in Eulerian and Lagrangian simulations. Small differences that do exist are explained by the inherent differences between the two schemes and their numerical implementation. The local droplet spectra differ substantially, again in agreement with the inherent limitations of the theoretical foundation behind each approach. There is a general agreement between simulations and Pi Chamber observations, with simplifications of the CCN activation and droplet growth equation used in the simulations likely explaining specific differences.
Spatially heterogeneous mechanisms underlying soil carbon sequestration as revealed via big data-driven Earth system modelling and deep learning
Authors: Luo Yiqi , Tao Feng , Huang Xiaomeng
Published: March 2020

It has long been known that processes that determine soil carbon dynamics are spatially heterogeneous. However, the spatially heterogeneous mechanisms have not been well characterized nor incorporated into Earth system models for predicting soil carbon sequestration in response to climate change. This presentation shows our recent results from an integrated approach that combines deep learning, data assimilation, big data with >100,000 vertical soil organic carbon (SOC) profiles worldwide, and the Community Land Model version 5 (CLM5) to optimize the model representation of SOC over the world. Our results indicate that CLM5 that is trained by >100,000 data via data assimilation alone is constrained with spatially homogeneous parameter values over the globe. However, CLM5 that is not only trained by data assimilation but also optimized by deep learning from the big data is constrained with spatially heterogeneous parameter values. Our further analysis suggests that those parameters representing microbial carbon use efficiency greatly vary across space. The spatial heterogeneity in carbon use efficiency is caused by interactions of edaphic, climate and vegetation factors. When the spatially heterogenous parameterization is applied to simulation over time with temporal variation, CLM5 predicts substantial carbon sequestration under climate change. In contrast, CLM5 with the spatially homogeneous parameters predicts carbon loss. Our study demonstrates the importance to uncover and represent spatially heterogeneous mechanisms underlying soil carbon sequestration in order to realistically predict SOC dynamics in the future.
MATLAB tools for the post-processing of GRACE temporal gravity field solutions
Authors: Piretzidis Dimitrios , Sideris Michael
Published: March 2020

We present a collection of MATLAB tools for the post-processing of temporal gravity field solutions from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. GRACE final products are in the form of monthly sets of spherical harmonic coefficients and have been extensively used by the scientific community to study the land surface mass redistribution that is predominantly due to ice melting, glacial isostatic adjustment, seismic activity and hydrological phenomena. Since the launch of GRACE satellites, a substantial effort has been made to develop processing strategies and improve the surface mass change estimates.

The MATAB software presented in this work is developed and used by the Gravity and Earth Observation group at the department of Geomatics Engineering, University of Calgary. A variety of techniques and tools for the processing of GRACE data are implemented, tested and analyzed. Some of the software capabilities are: filtering of GRACE data using decorrelation and smoothing techniques, conversion of gravity changes into mass changes on the Earth’s spherical, ellipsoidal and topographical surface, implementation of forward modeling techniques for the estimation and removal of long-term trends due to ice mass melting, basin-specific spatial averaging in the spatial and spectral domain, time series smoothing and decomposition techniques, and data visualization.

All tools use different levels of parameterization in order to assist both expert users and non-specialists. Such a software makes the comparison between different GRACE processing methods and parameters used easier, leading to optimal strategies for the estimation of surface mass changes and to the standardization of GRACE data post-processing. It could also facilitate the use of GRACE data to non-geodesists.
Development and application of NMEFC Arctic Ice-Ocean Prediction System (ArcIOPS) of CHINA
Authors: Liang Xi , Zhao Fu , Li Chunhua , Zhang Lin
Published: March 2020

NMEFC provides sea ice services for the CHINARE since 2010, the products in the early stage (before 2017) include satellite-retrieved and numerical forecasts of sea ice concentration. Based on MITgcm and ensemble Kalman Filter data assimilation scheme,  the Arctic Ice-Ocean Prediction System (ArcIOPS v1.0), was established in 2017. ArcIOPS v1.0 assimilates available satellite-retrieved sea ice concentration and thickness data. Sea ice thickness forecasting products from ArcIOPS v1.0 are provided to the CHINARE8, and are believed to have played an important role in the successful passage of R/V XUELONG through the Central Arctic for the first time during the summer of 2017. In 2019, ArcIOPS v1.0 was upgraded to the latest version (ArcIOPS v1.1), which assimilates satellite-retrieved sea ice concentration, sea ice thickness, as well as sea surface temperature (SST) data in ice free areas. Comparison between outputs of the latest version of ArcIOPS and that of its previous version shows that the latest version has a substantial improvement on sea ice concentration forecasts. In the future, with more and more kinds of observations to be assimilated, the high-resolution version of ArcIOPS will be put into operational running and benefit Chinese scientific and commercial activities in the Arctic Ocean.
Comprehensive Source Identification and Apportionment Analysis of five Heavy Metals in Soils in Wenzhou City, China
Authors: Shao Shuai , Hu Bifeng , Zhou Yin , Shi Zhou
Published: March 2020

Source identification and apportionment of heavy metals (HMs) has been a vital issue of soil contamination restoration. In this study, qualitive approaches (Finite mixture distribution model (FMDM) and raster based principal components analysis (RB-PCA)) as well as quantitative approach (positive matrix factorization (PMF)) were composed to identify and apportion sources of five HMs (Cd, Hg, As, Pb, Cr) with the help of several crucial auxiliary variables in Wenzhou City, China. The result of FMDM showed Cd, and Pb fitted for single log-normal distribution, while Hg fitted for double log-normal mixed distribution, and As, Cr presented triple log-normal distribution. Each element was identified and separated from natural or anthropogenic sources. An improved score interpolation map of PCA attached with corresponded auxiliary variables analysis suggested three main contribution sources including parental materials, mines exploiting and industrial emissions contributes most in the whole study area. Each element was further discussed for quantitative contributions through PMF model. Parental materials contributed to all elements (Cd, Hg, As, Pb, Cr) as 89.22%, 84.81%, 7.31%, 35.84%, 27.42%. Industrial emissions had a contribution as 2.94%, 80.77%, 15.93%, 4.79%, 25.63% for each element respectively. While Mine exploiting mixed with fertilizers inputs has dedicated for such five HMs as 7.84%,11.92%, 48.23%, 10.40% and 46.95%. Such results could efficiently be devoted to scientific decisions and strategies making regarding HMs pollution regulation in soils.
Spatiotemporal Variation of Drought and Associated Multi-Scale Response to Climate Change in Southeast Qinghai–Tibet Plateau, China
Authors: Liu Liu , Li Hao , Niu Qiankun , Lun Yurui , Xu Zongxue
Published: March 2020

Drought is one of the most widespread and threatening natural disasters in the world, which has terrible impacts on agricultural irrigation and production, ecological environment, and socioeconomic development. As a critical ecologically fragile area located in southwest China, the Yarlung Zangbo River (YZR) basin is sensitive and vulnerable to climate change and human activities. Hence, this study focused on the YZR basin and attempted to investigate the spatiotemporal variations of drought and associated multi-scale response to climate change based on the scPDSI (self-calibrating Palmer drought severity index) and CRU (climate research unit) data. Results showed that: (1) The YZR basin has experienced an overall wetting process from 1956 to 2015, while a distinct transition period in the mid 1990s (from wet to dry) was detected by multiple statistical methods. (2) Considering the spatial variation of the scPDSI, areas showing the significantly wetting process with increasing scPDSI values were mostly located in the arid upstream and midstream regions, which accounted for over 48% area of the YZR basin, while areas exhibiting the drying tendency with decreasing scPDSI values were mainly concentrated in the humid southern part of the YZR basin, dominating the transition period from wet to dry, to which more attention should be paid. (3) By using the EEMD (ensemble empirical mode decomposition) method, the scPDSI over the YZR basin showed quasi-3-year and quasi-9-year cycles at the inter-annual scale, while quasi-15-year and quasi-56-year cycles were detected at the inter-decadal scale. The reconstructed inter-annual scale showed a better capability to represent the abrupt change characteristic of drought, which was also more influential to the original time series with a variance contribution of 55.3%, while the inter-decadal scale could be used to portray the long-term drought variation process with a relative lower variance contribution of 29.1%. (4) The multi-scale response of drought to climate change indicated that changes of precipitation and diurnal temperature range (DTR) were the major driving factors in the drought variation at different time scales. Compared with potential evapotranspiration, DTR was a much more important climate factor associated with drought variations by altering the energy balance, which is more obvious over the YZR basin distributed with extensive snow cover and glaciers. These findings could provide important implications for ecological environment protection and sustainable socioeconomic development in the YZR basin and other high mountain regions.
Forest vulnerability and tree mortality in the Mediterranean: Impacts and Opportunities
Authors: Klein Tamir
Published: March 2020

The Mediterranean basin is a mosaic of human and natural landscapes, many of which are important forests and woodlands. Among global biomes, it has been under the longest anthropogenic stress, and today, in addition to the ongoing warming, it experiences drying. In my talk I will give examples from new research on the impacts of these processes on Mediterranean forests, as well as opportunities for increasing their sustainability under intensifying change.

Aleppo pine is perhaps the single most important forest tree species for the region, and has been grown for decades in common garden plots of provenances from around the region. Forest scientists from Spain, Italy, Greece and Israel, teamed up to synthesize the results of these provenance trials. Together, we produced the temperature and precipitation growth sensitivity profiles for Aleppo pine. Next, these profiles were applied on future climate maps, to show the potential expansion of this key species northward, as well as its extinction in many southern locations. In a seven decades-long tree mortality study across Israel, this mortality pattern is already occurring, driven by hotter and longer drought periods.

My current research is focused on finding new avenues to ensure the long-term existence of forests and trees in the Mediterranean. Examples include: (1) Mixed forests, with native broadleaf and conifer species coexisting, have high resilience, thanks to interspecific niche partitioning; (2) Native fruit trees have higher drought resistance than their cultivated relatives, and should be protected and integrated into local agriculture; (3) Native savannah trees from the southern fringes of the region are becoming more important, and offer new resilience strategies; and (4) Variations among Aleppo pine ecotypes give hope for the future suitability of this species across the Mediterranean.
Outgoing Longwave Radiation and Its Diurnal Variation from Combined FY3D and FY4A
Authors: Zhang Wanchun
Published: March 2020

The outgoing longwave radiation (OLR) is a crucial parameter for studying many areas in the atmospheric science, including the investigations of the cloud/water vapor/radiative interaction processes, climate variability, and for climate change monitoring and numerical model evaluation and diagnostics, etc. The OLR has continued being observed or estimated from Fengyun meteorological satellites, including solar orbit satellites (such as FY3D/MERSI) and geostationary satellites (such as FY4A/AGRI).

The advantage of solar orbiting satellites is global coverage. Thus it is difficult to reflect the diurnal variation of OLR for twice observations a day. While geostationary satellites are observed 24 times a day, which can accurately describe the diurnal variation of OLR. But its coverage is limited. Therefore, the development of OLR fusion products combined with solar orbit satellite and geostationary satellite, can improve product accuracy without losing coverage advantage. In this study, we use OLR from FY4A and FY3D to build a fusion OLR product to correct the diurnal variation of OLR, and get good results.
New observations of late summer bio-physical ice and snow conditions in the northwestern Weddell Sea
Authors: Arndt Stefanie , Haas Christian , Peeken Ilka
Published: March 2020

Summer sea ice extent in the Weddell Sea has increased overall during the last four decades, with large interannual variations. However, the underlying causes and the related ice and snow properties are still poorly known. Here we present results of the interdisciplinary Weddell Sea Ice (WedIce) project carried out in the northwestern Weddell Sea on board the German icebreaker R/V Polarstern in February and March 2019, i.e. at the end of the summer ablation period. This is the region of the thickest, oldest ice in the Weddell Sea, at the outflow of the Weddell Gyre. Measurements included airborne ice thickness surveys and in-situ snow and ice sampling of mostly second- and third year ice. Preliminary results show mean ice thicknesses between 2.6 and 5.4 m, increasing from the Antarctic Sound towards the Larsen B region. The ice had mostly positive ice freeboard. Mean snow thicknesses ranged between 0.05 and 0.46 m. Snow was well below the melting temperature on most days and was highly metamorphic and icy, with melt-freeze forms as dominant snow type. In addition, as a result of the summer’s thaw, an average of 0.14 m of superimposed ice was found in all ice cores drilled during the cruise. Although there was rotten ice below a solid, ca. 30 cm thick surface ice layer, pronounced gap layers typical for late summer ice in the marginal ice zone were rare, and algal biomass was patchily distributed within individual sea ice cores. Overall, there was a strong gradient of increasing ice algal biomass from the Larsen B to the Antarctic Sound region. The presented results show that sea ice conditions in the northwestern Weddell Sea are still severe and have not changed significantly since the last observations carried out in 2004 and 2006. The presence of relatively thin, icy snow has strong implications for the ice and snow mass balance, for freshwater oceanography, and for the application of remote sensing methods. Overall sea ice properties strongly affect the biological productivity of this region and limit carbon fluxes to the seafloor in the northwestern Weddell Sea.
The Structural Characteristics of Salt Rocks and Their Impact on the Oil and Gas Distribution in Yingxiongling Area, Qaidam Basin
Authors: Na Wu
Published: March 2020

Qaidam Basin is located at the northern Tibetan Plateau, western China. It is a rifted basin bounded by the Alkin, Qilian and Kunlun Mountains and filled by well-developed Cenozoic strata. The study focus is the Cenozoic upper and lower Ganchaigou formations which have significant influence on hydrocarbon distribution. The exploration discoveries in recent years are mainly concentrated in the sub-salt traps within lower Ganchaigou Formation.

The salt rock of the lower Ganchaigou formation have multiple unique structural characteristics. First, these salt rocks have a wide distribution and a large thickness. they are mainly distributed in the western part of Yingxiongling and Youyuangou area, with a stable thickness up to 300m, which are caused by extrusion due to major orogeny. Second, these rocks are characteristics by strong fluidity and plasticity. Influenced by tectonic movement, the salt strata show “dual structure”, as slide above and deep thrust below. Several traps are developed within the slide structural above and Layered or massive fractured carbonate rock traps are developed below and within salt strata in the lower deep trust belt. Third, salt rock has strong sealing ability. The widely distributed salt strata blanket the traps with lower Ganchaigou Formation. During the extrusion tectonic, the flow and wedging of the salt rocks expand the distribution area of the original salt depositions, resulting in enhancement of cap rock effectiveness.

The salt rocks of the lower Ganchaigou formation have significant impact on the oil and gas distribution. First, the slide movement formed two layers of deep and shallow oil and gas systems, and the widely developed structural traps are good hydrocarbon reservoirs, providing high-quality resources for multiple exploration. The seal ability of rock salts has a greater impact on reservoir performance. Second, the deep and high-yield oil and gas reservior in the western part of Yingxiongling area mostly distribute within the lower salt rocks. Compared with the upper shallow reservoirs, they have higher reservoir pressure and higher single-well production. At the same time, the area of a single reservoir under the salt is also large.
A wedgelet current system on Saturn
Authors: Guo Ruilong , Yao Zhonghua , Palmaerts Benjamin , Dunn William , Sergis Nick , Grodent Denis , Ye Shengyi , Pu Zuyin , Yates Japheth , Badman Sarah , Wei Yong
Published: March 2020

Magnetic energy and mass release processes are key issues to understand the magnetospheric dynamics and aurorae processes on planets. Recent studies reveal that rotationally driven processes at dayside on giant planets are much more important than we ever expected. The discovery on the dayside magnetodisc reconnection demonstrates that the rotation effect can overcome the solar wind compression to sufficiently stretch magnetic field lines at dayside (Guo et al., 2018, doi: 10.1038/s41550-018-0461-9). A long-standing small-scale reconnection process was also shown at all local times (Guo et al., 2019, doi: 10.3847/2041-8213/ab4429). Using Cassini in situ multiple instruments data, we here proposed a wedgelet current system governing the entire magnetosphere of Saturn, which can explain the observational phenomena of quasi-periodical electron energization recurrence and beads-like structure in the main aurora region. Localized active regions with finite azimuthal lengths in the magnetosphere were discretely and azimuthally distributed along the magnetodisc and rotated with the magnetosphere. The electron energizations recurred at the spacecraft are related to each active region that passed by. These studies reveal that the dynamics in magnetodisc are global effects on giant planets, which are not always restrained at nightside.
Mineral reservoirs and behaviors of hydrogen in Earth’s lower mantle
Authors: Hu Qingyang , Mao Ho-kwang
Published: March 2020

The incorporation of H into minerals imposes profound effects on their physicochemical signatures of the solid Earth. The locations of hydrogen reservoirs are detected by seismology. However, the mineral responsible for storing large quantity of hydrogen, particularly in Earth’s lower mantle is still controversial. Combining a set of in-situ probes at high pressure-temperature and first principles simulation, we investigated the solubility and behaviors of H in silica and hydroxide up to the conditions found at the core-mantle boundary. The solubility of hydrogen keeps high in those minerals even along the mantle geotherm. Under deep lower mantle pressures, hydrogen atoms are free from the hydroxyl bonding and becomes highly diffusive. The swift diffusion of hydrogen ions induces soaring electrical conductivity when the sample is laser heated. Those exotic properties indicate novel transport mechanisms for both charge and mass at Earth’s deep lower mantle. The potential of hydrogen enriched volatile reservoirs may carry major impacts on the electrical and magnetic behaviors, as well as redox, H isotopic mixing, and other geochemical processes in the Earth’s deep interiors.
Redistribution of landslide debris through episodic heavy rainfall events as revealed by multi-period Lidar DEMs
Authors: Chan Yu-Chang , Hsieh Yu-Chung , Chang Kou-Jen
Published: March 2020

Landslides are commonly triggered by heavy rainfall events, but how the loose landslide debris is redistributed through time and how fast the landslide scars are healed by vegetation are not well and precisely documented. Due to recent advances in airborne Lidar-derived digital elevation models, we are able to obtain precise DEMs at different time periods and analyze the redistribution of landslide debris that was once difficult to measure because of relatively minor elevation changes. Three periods of Lidar-derived DEMs were used to analyze a drainage basin that was affected by a heavy rainfall event and generated several landslide deposits and scars within the drainage basin in Taiwan. We selected a single drainage basin to better constrain the source of landslide debris for subsequent observations of landslide debris removal. How the landslide debris is transported and redistributed remains an important topic for understanding debris removal and evaluating post-landslide hazards in downstream areas. The multi-period high-resolution Lidar DEMs give the necessary accuracy to calculate small but significant volume changes that were not easily detectable from previous measuring techniques. Our results show that the landslide debris redistributed most effectively during later large rainfall events, and the landslide materials are minimally redistributed during small rainfall events. Areas without existing landslides were also insignificantly affected in terms of volume change even during large rainfall events. The standard deviation of elevations in the drainage basin is used to show how the topography was changed due to heavy rainfall events within the drainage basin. The concept of surface roughness may be useful to characterize the dissipation of landslide debris because the roughness values become lower during the debris redistribution process. The redistribution of landslide debris over the observed years suggests that the dissipation of landslide debris is mainly affected by by episodic heavy rainfall events and the landslide scars recover relatively quickly for smaller affected landslide regions.
The Influence of Shallow Foehn on Atmospheric Diffusion Conditions and Air Quality over Urumqi in Winter
Authors: keming Zhao
Published: March 2020

Using hourly air pollutants concentration from six environmental monitor stations, meteorological data and wind profile radar data in winter during 2013-2015, the influences of shallow foehn on diffusion conditions and air pollution concentration over Urumqi were analyzed. The results showed the occurrence frequency of shallow foehn was 57.3% in Urumqi in winter. The flow depth, base height and top height of shallow foehn were about 1500 m, 600 m and 2100 m, respectively. The maximum mixing layer depth, the inversion depth, the temperature difference between the top and bottom of inversion layer on foehn days were 200 m lower, 344m thicker and 4.4℃ higher than the corresponding values on non-foehn days, respectively. However, the differences of wind speed and inversion intensity between on foehn days and on non-foehn days were slight. Also, the frequency of each pollution level on foehn days was higher than on non-foehn days with extra frequency of 18% from level Ⅲ to level Ⅵ. Moreover, there was foehn existence on days with air pollution level Ⅵ. Except for O3, the other five air pollutant concentrations at each environmental station on foen days were all higher than on non-foehn days but with similar diurnal variation. The spatial distributions of six air pollutants on foehn days and non-foehn days were almost same. Overall, the air quality at south urban area was relative excellent than other areas.
Towards AOD1B RL07
Authors: Shihora Linus , Poropat Lea , Dobslaw Henryk
Published: March 2020

The Atmosphere and Ocean non-tidal De-aliasing Level-1B (AOD1B) product is widely used internationally to correct for transient effects of atmosphere-ocean mass variability on Earth satellites at in particular low altitudes. The most recent release 06 is given every 3 hours in Stokes coefficients expanded up to degree and order 180. It is based on ERA-Interim and ECMWF operational data for the atmosphere, and simulations with the global general ocean circulation model MPIOM consistently forced with fields from the same atmospheric data-set. RL06 was introduced in the year 2016 and is routinely updated every 24 hours with all data-sets for the previous calendar day.

Based on a stationary error assessment for AOD1B RL06 that might be also used to explicitly characterize uncertainties of AOD1B in the gravity field estimation process, we present preliminary numerical experiments with the TP10 configuration of MPIOM in preparation of a new AOD1B version 07 which is planned to be released in the year 2021. Those experiments test effects of (i) the new hourly atmospheric forcing data-set from the latest reanalysis ERA-5 of ECMWF; (ii) a revised bathymetry in particular around Antarctica that also includes cavities underneath the ice-shelves; and the consideration of shielding effects of the ice cover; and (iii) the consequences of self-attraction and loading feedbacks on the ocean dynamics. Results will be discussed in terms of differences with respect to RL06, in situ ocean observations, and alternative model data-sets.