bluuebunny/crossref_metadata_2025 huggingface dataset:
Summer Eurasian Heat Wave and its linkage to SST anomalies over North Atlantic and Barents-Kara Seas
Authors: Wang Hejing , Luo Dehai
Published: March 2020

In our study, we aim to examine what factors lead to the summer heat waves over Eurasia and their variability. The analysis reveals that the summer heat waves over Eurasia show two kinds of spatial patterns: midlatitude and high latitude types. The mid-latitude heat wave mainly occurred over west Russia in the west of 55°E and in the south of 60°N, whereas the high-latitude type mainly occurred over west Russia in the east of 55°E and in the north of 55°N. We further analyzed the relationship of the two kinds of heat waves with atmospheric circulation patterns in the Atlantic-Eurasian sector and sea surface temperature (SST) anomalies over the North Atlantic and Arctic. The results show that the cold or warm SST anomalies over Barents-Kara Seas (BKS) can significantly influence the latitude and longitude of Russian heat waves, while the heat waves are also related to the latitude of positive SST anomalies over North Atlantic.

A mid-latitude wave train propagating into Eurasia and mid-latitude Russian heat waves, which are related to the positive phase of the North Atlantic Oscillation (NAO), are seen when there are strong SST warming in the North Atlantic mid-high latitudes south of 60°N and SST cooling over BKS. In contrast, a high-latitude Russian heat wave can occur over west Russia when there are positive SST anomalies over Baffin Bay, Davis Strait and Labrador Sea north of 60°N and BKS, while this high-latitude wave train is related to the decay of Greenland blocking or the negative NAO phase via high-latitude wave train propagation.
Experimental Modelling of Black Carbon Emissions from Gas Flares in the Oil and Gas Sector
Authors: Mehr Parvin , Conrad Bradley M. , Johnson Matthew R.
Published: March 2020

Flares in the upstream oil and gas (UOG) industry are an important and poorly quantified source of black carbon (BC) emissions and may be a dominant source of black carbon deposition in sensitive Arctic regions (Stohl et al. 2013).  Accurate estimation of flare BC emissions to support informed policy decisions, accurate climate modeling, and new international reporting regulations under the Gothenburg protocol is a critical challenge.  To date few studies have focussed on the primarily buoyancy-dominated turbulent non-premixed flames typical of upstream oil and gas flares, such that existing emission factor models are highly uncertain (see (McEwen and Johnson 2012)).  Although recent progress has been made in measuring black carbon from flares in the field (e.g. (Conrad and Johnson 2017; Johnson et al. 2013), data have also shown that emissions of individual flares may vary by more than 4 orders of magnitude. 

The objective of the current study is to develop a robust data-backed model to predict black carbon emissions from flares considering variations in flare gas composition, flow rates, and stack diameters.  Laboratory measurements of black carbon (soot) for a range of turbulent non-premixed jet diffusion flames of up to 3 m in length were performed at the Carleton University Flare Facility in Ottawa, Canada.  Two hundred and thirty cases spanning five flare stack diameters (25.4 to 76.2 mm), exit velocities from 0.16 to 15.15 m/s, and a broad range of industrially-relevant multicomponent (C1-C7 hydrocarbons, CO2, N2) flare gas compositions were studied.  Emissions were captured in a large (~3.1 m diameter) sampling hood and forwarded to gas- and particulate phase analyzers. 

Black carbon concentrations were measured via a Sunset Labs thermal-optical instrument using the OCECgo software tool (Conrad and Johnson 2019) to quantify uncertainties via Monte Carlo analysis.  BC yields were subsequently calculated using a mass-balance methodology (Corbin and Johnson 2014).  Variability in BC yield was well-predicted by an empirical model incorporating both the aerodynamic and chemistry effects.  For this range of conditions, it was observed that primary independent variables (such as exit velocity and higher heating value) act as reasonable surrogates for sooting propensity.  Further experiments are underway to test the proposed model over a broader range of conditions.  However, results to date represent a significant advance in our ability to predict black carbon emissions from flares.
Dam Deformation Prediction Based on EEMD-ELM Model
Authors: Yan Tao , Chen Bo
Published: March 2020

Establishing a reasonable and reliable dam deformation monitoring model is of great significance for effective analysis of dam deformation monitoring data and accurate assessment of dam working conditions. Firstly, the dam deformation is decomposed by the EEMD algorithm to obtain IMF components representing different characteristic scales, and different influencing factors are selected for different IMF components. Secondly, each IMF component is used as the ELM training sample to analyze, fit and predict the dam deformation component. Finally, the prediction results of each IMF component are accumulated to obtain the dam deformation prediction value. Taking a roller compacted concrete gravity dam as an example, the EEMD-ELM model is used to predict the deformation of the dam. At the same time, it is compared and analyzed with the prediction results of the BPNN model and the ELM model. The mean square error of the EMD-ELM model is 0.566, which is 54% and 14.8% lower than the BPNN model and the ELM model, indicating that the EEMD-ELM model has higher prediction accuracy and has certain application value.

Key words: dam deformation;prediction model; ensemble empirical mode decomposition; extreme learning machine
Features of ionospheric responses to geomagnetic storms of low solar activity period
Authors: Cherniak Iurii , Wang Wenbin , Zakharenkova Irina
Published: March 2020

During low solar activity periods, geomagnetic disturbances still occur and impact the Earth’s ionosphere. In such conditions, even comparatively weak disturbances can lead to a noticeable ionospheric response. In particular during the extended solar minimum of the 23rd solar cycle, the October 11, 2008 geomagnetic storm of moderate intensity (Dst = -50 nT, maximum Kp=6) caused strong positive ionospheric disturbances. At midlatitudes, the storm-induced enhancement in total electron contain (TEC) exceeded by two times the normal quite time day-to-day variability and the strong density enhancement was registered in the topside ionosphere.

Using a combination of the ground-based and low-Earth-orbit (LEO) observations (ground-based GNSS networks, LEO RO COSMIC, in-situ and onboard GPS CHAMP and Swarm measurements, space-based optical observations), we examined features of ionospheric responses to several weak-to-moderate geomagnetic storms occurred at low solar activity periods of the 23rd and 24th solar cycles (2008 and 2019 years respectively). The ionospheric response was analyzed in terms of the storm-time TEC changes, large and medium scale travelling ionospheric disturbances generation, and auroral plasma irregularities intensity and location. The prominent features obtained were an intensification of ionospheric irregularities occurrence at sub-auroral latitudes and an equatorward expansion of the auroral irregularities oval, differences of TEC variations from quite-time variability, response of the topside ionosphere, and TIDs generation.

The first-principle TIEGCM simulations with a comprehensive data-model comparison was carried out to specify the main drivers responsible for the observed ionospheric responses.

This work is supported by the NASA LWS grant NNX15AB83G.
Deployment of Green roof top as a Nature Based Solution in Dublin, Ireland
Authors: Sarkar Basu Arunima , Basu Bidroha , Sannigrahi Srikanta , Pilla Francesco
Published: March 2020

In the recent past, severe flooding have caused major natural disasters leading to severe damage to public property, infrastructure and human life. The threat of flooding can be attributed to rapid growth in population, uncontrolled urban expansion, global warming and climate change. It has been reported that more than 100,000 people were killed and over 1.4 billion people were affected worldwide due to flooding over the past ten years. The main contributing factors of flooding that affect death or injury to people include flood depth, velocity of flood flow and the degree to which people are exposed to flood in the region. A significant increase in rate of flooding occurred due to decrease in vegetation cover and increase in the imperviousness at urban areas, leading to decrease in the efficiency of urban drainage system that increase proneness of flooding. This study identifies an innovative approach to flood control by deployment of a Nature based solution (NBS). NBS is relatively new approach to tackle flooding and is a solution framed with an inspiration and support from nature. This research focuses on addressing the following three questions: which NBS to deploy, how to identify the ideal site for deployment of the selected NBS, and how to quantify the effectiveness of the deployed NBS in terms of flood control/reduction? As a part of the EU Horizon 2020’s OPERANDUM project, the case study is being conducted at Dublin as the Open Air Laboratory Ireland. The NBS implementation study has been initiated along with the partnership of Dublin City Council. Preliminarily, city planning rules and land development guidelines were reviewed from Dublin and green roof was selected as the potential NBS. Subsequently, rainfall-runoff based hydrological modelling was performed to assess the potential flood hazard areas and to identify an effective location for implementation of NBS. For this purpose, the hydrological model was simulated with and without the presence of NBS at different potential locations and the site exhibiting highest flood control was selected to be the optimal location. The selected location is close to the Dublin Port and adjacent to River Liffey, which is the main river in Dublin. In order to show the effectiveness of the green roof NBS, real world data has been collected before and after implementation of the NBS to assess its effectiveness in real world framework.
Impacts of terracing on hydrological processes: a case study in Wangmaogou watershed of the Loess Plateau
Authors: Chen Xiuxiu , Ran Qihua , Hong Yanyan , Ye Sheng
Published: March 2020

The Loess Plateau of China is known for its severe soil and water loss problems. Terracing is one of the most important soil and water conservation measures there. Our understanding of the effects of terraces on soil and water conservation and its mechanism is limited by observation data on runoff and soil erosion as well as the influences from local environmental characteristics. In this study, we applied a physically-based distributed hydrological model (Integrated Hydrology Model, InHM) to an experimental terrace in Wangmaogou watershed of the Loess Plateau, and validated it with the measured soil water content. Our results suggested that terrace construction can substantially reduce runoff by changing the flow direction, especially during heavy rainfall events. This reduction in runoff would be greatly attenuated when ridges are damaged due to lack of maintenance. Under the rainfall intensity of 120 mm/h, compared with hillslope, a well-maintained terrace could reduce runoff by 100%, while the terrace without ridges could only reduce 28% runoff. Besides, ridges not only prevented water from flowing out of platforms, but also helped maintain the risers from terrace failure by decreasing about 20% of the saturation rate at the risers. Our results also emphasized the importance of evaporation, which could make up to 15% of the total water loss even during the rainfall events. Given the effects of terraces on water conservation, it is essential for the land use management of the Loess Plateau to take into account of the terracing approach, as well as a good maintenance of ridges.
Using remote sensing evapotranspiration solely calibrating hydrology model for predicting runoff time series in ungauged regions
Authors: Zhang Yongqiang
Published: March 2020

It is important yet challenging to predict runoff in data sparse regions or ungauged regions, majority of which belong to headwater catchments that are normally the major water source for middle and lower river reaches. There are numerous studies carried out since the launch of the Predictions in Ungauged Basins (PUB) initiative by the International Association of Hydrological Sciences (IAHS) in 2003. Most runoff prediction studies rely on modelling approaches via two steps. The first step is to calibrate the hydrological model against observed streamflow at the gauged catchments. The second step is regionalization in which the set of calibrated parameter values from a suitable donor catchment is used for predicting runoff in a targeted ungauged catchment. The major challenge of this approach is that when the gauged catchments are sparsely distributed or little available, it is hard to get sensible regionalization results. This study develops a new approach to calibrate a hydrological model purely against remote sensed actual evapotranspiration data obtained from 8-day and 500 m resolution PML-V2 products and the calibrated parameters can be directly used for runoff prediction across global land surface. This approach has been successfully used for predicting daily, monthly and annual runoff in Australia and southeastern Tibetan Plateau. This is an exciting research domain for hydrologists to pursue since remote sensing data is accumulated in a fast-increasing rate, and will provide researchers an unprecedent opportunity.
Cenozoic Nd isotopic variation of Asian dust in the northern Tibetan Plateau and the North Pacific Ocean
Authors: Yang Yibo , Fang Xiaomin , Galy Albert , Yang Rongsheng , Song Bowen , Liu Yudong
Published: March 2020

Cenozoic changes in climate, erosion, and atmospheric circulation in Asian interior continents can be reconstructed from records of eolian dust deposition from sediments of the North Pacific Ocean (NPO). Through a careful investigation of Nd isotope as eolian dust source tracer, the well-known core GPC3 in the central NPO has provided so far the most complete Asian dust records since ~40 Ma. Nd isotope in the GPC3 eolian dust thus documented an integrated history of Nd isotopic change of very fine eolian dust contributed from various geological terranes in Asian dust source areas. Unraveling this ~40 Myr-long Nd isotopic change in the NPO provides a first order constraint on the provenance change of the Asian dust source areas as a whole. However, this work cannot be done without an explicit Nd isotopic history for each geological terrane within the broad Asian dust source areas, since the Asian dust source area can be at least divided isotopically into two regions with distinct Nd isotopic values, e.g., the northern Tibetan Plateau (NTP) and the Central Asian Orogen (CAO). In this work, we present new data of river sediment Nd isotopic data around the entire Qaidam and Xining Basins to yield a more comprehensive Nd isotopic regimes at the NTP with compiling previously reported data. We have established an integrated Cenozoic Nd isotopic records of finer dust in the NTP based on previous records and our new Nd isotopic records in the Xining Basin from 52 to 17 Ma and Linxia basin from 23 to 5 Ma using both bulk sediments and clay fractions (<2 μm). After comparison of the reconstructed Nd isotopic variation in fine dust at the NTP with that in the NPO, we have further assessed the relative contributions of NTP and CAO to the Asian dust preserved in the NPO during the last 40 Myr, which indicates a dominant late Oligocene-Neogene uplift and growth of the mountains at the NTP and the CAO regions.
Landfast ice in the Canadian Sub-Arctic: A Hudson-Bay wide study.
Authors: Gupta Kaushik , Mukhopadhyay Anirban , Ehn Jens
Published: March 2020

Hudson Bay, along with James Bay, forms a significant section of the Canadian Sub-Arctic basin which experiences an annual event of Land-fast sea ice formation and melt. Here Landfast ice dynamics largely depends on the climatic and oceanographic conditions, along with coastal geomorphology. In this study, we attempt to investigate the annual cycle of land-fast sea ice formation and melt in the Hudson Bay and James Bay region by estimating the ice period, stages of development and extent. Through this study, we also emphasize the role of coastal morphology influencing ice stability. We have analysed over 2000 ice charts produced by the Canadian Ice Service (CIS) and satellite observations from Worldview and LANDSAT series. The Canadian Ice Service publishes charts of ice concentration and stages of development of Hudson Bay and James Bay on a monthly, weekly and daily scale. We observe the variation in land-fast ice dynamics by digitally extracting information from the daily and weekly ice charts produced by the CIS and satellite observation coupled with mean surface temperature throughout the period of study. Our results indicate landfast ice forming earlier and breaking later in the northern and north-western coastal margin of Hudson Bay as compared to the southern and eastern shore. James Bay experiences a relatively shorter ice season than Hudson Bay. Though time series analysis of break-up in the northern and north-western Hudson Bay shows a negative trend implying an earlier break-up in these regions. Southern and eastern Hudson Bay and James Bay have a positive trend implying a negligible change in the break-up period. The extent of landfast ice in the eastern coastal margins of Hudson Bay and James Bay was noted to be significantly more compared to the west, primarily due to the north to south and finally eastward movement of pack ice in the bay system. Complex coastal topography in the eastern coastal margin also contributes to the stability of these extended ice sheets. The study determines the description of the multiyear variability of land-fast sea ice under changing temperature regimes over the Canadian Sub-Arctic.
Will no-till be the new panacea for degraded tropical landscapes?
Authors: Steenhuis Tammo , Hussein Misbah , muche Habtamu , Belay Sisay , Gessess Azalu , Guzman Christian , Schmitter Petra , Reyes Manuel , Tilahun Seifu
Published: March 2020

General knowledge based on the good agricultural soils in temperate climates is that no-till and conservation-till practices increase infiltration of the rainwater and decrease runoff and erosion.  Experiments in the semi-humid Ethiopian highlands do not often show the same benefits and in many cases no-till actually increases runoff above conventional and deep tillage. In contrast, for conservation-tillage with mulch at the surface, more of the water infiltrates and enhances plant growth

Reduced tillage systems increase infiltration through soil fauna that form soil macropores through which rainwater flows to the subsoil bypassing the soil matrix with limited conductivity. Most degraded soils (at least in the Ethiopian highlands) have a hardpan at shallow depths restricting downward movement of water. Runoff on conventionally tilled soils is caused by saturation excess when the perched water table in the plowed soil layer reaches the surface.  Thus, the amount of runoff is determined by the water free pore space in the surface layer.  Since this pore space is less under no-till, no-till has greater amounts of runoff than conventional till. 

Under mulch tillage, organic matter is introduced at the surface and soil fauna becomes well-developed which will improve the soil structure and porosity of the soil.  This structure will be maintained because the mulch decreases the sediment concentration in the water and the pores will remain open. Under conventional tillage sediment concentrations are high and any pores formed will be filled up with sediment. Our expectation is that since organic matter under mixed farming is used to feed the cattle, widespread implementation of no-till and conservation tillage will be limited to areas with high value crops in which farmers can afford using organic matter as a mulch.
Assessing the Contribution of Oceanic Fluxes to the Global Budget of Carbonyl Sulfide
Authors: Suntharalingam Parvadha , Chen Zhaohui , Lennartz Sinikka , Buitenhuis Erik
Published: March 2020

Accurate quantification of the global budget of atmospheric carbonyl sulfide (COS) is needed given its role in atmospheric chemistry and the global carbon cycle. COS is the most abundant atmospheric sulfur gas. In the stratosphere, COS is photodissociated to provide a significant source of sulfate aerosol, a key agent of stratospheric ozone depletion.  In the troposphere, measurements of the COS variation have the potential to provide constraints on the rates of CO2 assimilation by terrestrial plants and hence on primary productivity. Accurate knowledge of the global budget of COS and of its respective source and sink fluxes is therefore needed to understand its impact on ozone depletion and on the carbon cycle. Recent estimates of the global COS budget, however, reveal discrepancies between known sources and sinks. In particular the magnitude of the oceanic flux (the largest known source to the atmosphere) remains uncertain. The ocean provides a source of COS to the troposphere through direct emission, and potentially through emission of COS precursors such as carbon disulfide (CS2). Here we assess the role of the ocean in the global COS budget using a global atmospheric transport model (GEOS-Chem) in combination with recent estimates of COS source and sink fluxes, and with available oceanic and atmospheric measurements of COS.  We compare different realizations of oceanic COS fluxes taken from ocean biogeochemistry models and from recent data syntheses, and assess their ability to reduce the uncertainty in the current global budget of COS.
Last glacial terrestrial vegetation record of leaf wax n-alcohols in the northern South China Sea: Contrast to scenarios from long chain n-alkanes
Authors: Mao Shengyi , Zhu Xiaowei , Sun Yongge , Liu Lihua , Wu Nengyou
Published: March 2020

Long chain n-alcohols and n-alkanes in core sediments from the northern South China Sea (SCS) were measured to make a comparison during terrestrial vegetation reconstruction from ~42 to ~7 ka. The results showed that terrestrial vegetation record from long chain n-alkanes matched well with previous studies in nearby cores, showing more C4 plants developed during the Last Glacial Maximum (LGM) and C3 plants dominated in the interglacial period. However, these scenarios did not occur during terrestrial vegetation reconstruction using long chain n-alcohols, i.e., showing C3 plant expansion during the LGM. The discrepancy during the interglacial period could be likely attributed to aerobic degradation of functionalized long chain n-alcohols due to the oxygen-rich SCS bottom water, resulting in the weak response of terrestrial vegetation signals. On the other hand, the difference between functionalized n-alcohols and non-functional n-alkanes to record local and distal vegetation signals, respectively might be a potential interpretation for the contradiction during the LGM when the SCS was characterized by low-oxygen deep water. Nevertheless, large variations on n-alkyl lipid compositions in C3/C4 plants could likely play a part in modulating sedimentary long chain n-alcohols and n-alkanes towards different vegetation signals, and caution must be taken in respect to the terrestrial vegetation reconstruction using long chain n-alkanes and long chain n-alcohols.
Geographic features of the distribution of bottom fluxes of nutrients (N, P, Si) in the frontal zone of the Ob River estuary
Authors: Borisenko Gennadii
Published: March 2020

Gulf of Ob - the closing estuary of the Ob River, where fresh and saltwater are mixing. This is a very large and long stretch of water: about 800km in length and 30 to 90 km in width. The impressive size of the Gulf of Ob and the impact on the Kara Sea (runoff 530 km3 / year) give to Ob Estuary regional significance. River Ob bringing the largest amount (75%) of freshwater to the Gulf of Ob - an important industry flux and transport artery of Western Siberia, which in turn creates anthropogenic load on the estuary (surfactants, oil products, excess amounts of organic substances).

Changes in salinity, acidity, alkalinity in frontal zones cause a chain reaction of subsequent physicochemical processes leading, in turn, to the deposition of more than 90% of sedimentary material and dissolved organic matter inputted by Ob. Inorganic forms flows of phosphorus from the sediment at the frontal zone is low, which is explained by the high content of Ferrum(III+) oxide.

The fluxes of silicon and nitrogen did not significantly change, however, high absolute values of the silicon content in the mixing zone of fresh and sea waters are observed, which may be associated with the phenomenon of "avalanche" sedimentation observed in this zone.

This work was supported by the grant of the Russian Science Foundation 19-17-00196 Dissolved transformation runoff in estuarine regions of Russian rivers of various climatic zones

 
Monitoring of Flood and Inundation Dynamics in Coastal Texas and Louisiana Using Airborne UAVSAR Data and Deep Learning Classification Techniques
Authors: Jin Huiran , Liu Tao
Published: March 2020

Floods and inundations caused by storm surges and prolonged heavy precipitation frequently affect the Gulf Coast of the United States. During the Atlantic hurricane season, many of the streams and bayous in this region may overflow or break their banks, resulting in severe damage to private properties and public facilities. Reliable information on the spatial distribution and temporal variation of flood and inundation extent is fundamental to the design and implementation of effective disaster preparedness, response, recovery, and mitigation activities. This research aims to develop new algorithms for improved characterization of flood and inundation dynamics using airborne repeat-pass SAR data acquired by NASA/JPL’s polarimetric L-band UAVSAR system. A series of UAVSAR data collected over southeast Texas and southwest Louisiana in summer 2019 are processed to extract surface water extent before and after Tropical Storm Imelda, the fifth-wettest tropical cyclone on record in the continental United States that brought heavy rain and catastrophic flooding. Various metrics derived from polarization decomposition of the quad-polarized radar signals constitute the feature space. Deep learning (DL), a powerful state-of-the-art technique for image classification and big data analytics, is applied and multi-level DL frameworks are established to separate water and partial inundated from land areas. Results show that using fine-tuned 2-D convolutional neural networks (CNNs) with convolutions in both polarimetric and spatial domains can lead to improved classification accuracies over those achieved by conventional machine learning algorithms such as support vector machines (SVMs). Inundation changes with respect to different land-cover/land-use (LCLU) types are also analyzed, and more extensive inundated areas are observed in emergent and non-vegetated wetlands close to the coast. The approaches developed in this study have the potential to assist in future flood and inundation monitoring and impact analysis, and the classified maps created will largely facilitate the investigation of local hydrological processes and water storage assessment.
The upper atmospheric responses to tidal and planetary waves
Authors: Gu Sheng-Yang
Published: March 2020

Tidal and planetary waves (PWs) in the mesosphere and lower thermosphere region could have significant impact on the upper thermosphere/ionosphere system through direct propagations, E region wind dynamo, and the change of residual circulations. We would like to show some results from BeiDou and COSMIC observations, as well as TIME-GCM simulations, to illustrate the lower/upper atmospheric couplings through different mechanisms. Generally, the spatial structures of the ionospheric responses to planetary waves agree with the ionospheric fountain effect, which indicates the important roles of equatorial wind dynamos in transmitting planetary wave signals to the ionosphere. The TIME-GCM simulations show that the zonal and meridional components of the planetary waves could result in evident vertical ion drift perturbations, while the net ionospheric effect is related to both their latitudinal structures and phases. The simulations also show that the change of tidal amplitudes and secondary PWs generated by PW-tide interaction are also important to the ionospheric variabilities. Besides, the couplings through PW-induced residual circulations are exhibited by both model simulations and TEC observations from BeiDou satellite system.
Discrepancy in radiative feedbacks between models and observations tied to models inability to reproduce historical surface temperature patterns over the tropical Indo-Pacific.
Authors: Proistosescu Cristian , Dong Yue , Stuecker Malte , Armour Kyle , Wills Robb , Parsons Luke
Published: March 2020

How much Earth warms in response to radiative forcing is determined by the net radiative feedback, which quantifies how much more energy is radiated to space for a given increase in surface temperature.  Estimates from present day observations of temperature and earth's energetic imbalance yield a strongly negative radiative feedback, or, equivalently, a very low climate sensitivity, which lies outside the range of climate sensitivity in coupled climate models. This discrepancy in radiative feedbacks can be linked to discrepancies between models and observations in the pattern of historical sea-surface temperature (SST) anomalies driving tropical atmospheric circulation and radiative damping.  Indeed, we find that an atmospheric model (CAM5) forced with observed SSTs yields a net feedback that is consistent with observational estimates, but up to three times more negative than that from the same period (2000-2017) in historical simulations where the same atmospheric model is coupled to a dynamical ocean model (CESM1). 

To understand the role natural variability can play in this discrepancy, we compare the radiative feedbacks generated by the observed pattern of SSTs to those within the CESM1 large ensemble over the same period. The large ensemble produces a wide range of feedbacks due to internal variability alone. Yet, global radiative feedbacks (cloud feedbacks in particular) generated by observed warming patterns are far outside the range of natural variability in the large ensemble. Using both a Green's function approach, as well as a simple metric based on the East-West tropical pacific gradient, we show that none of the control simulations of CMIP5 climate models can generate sufficiently large natural variability to explain the discrepancy between models and observations. We conclude that the discrepancy in SST patterns, and the resulting discrepancy in radiative feedbacks, is caused by an deficiency in models' ability to simulate either natural variabilty or the forced response over the recent historical period. We will also show preliminary analysis from CMIP6 simulations.
Atmospheric observations of CO2, 14CO2 and O2 concentrations to capture fossil fuel CO2 emissions from the Greater Tokyo Area
Authors: Terao Yukio , Tohjima Yasunori , Ishidoya Shigeyuki , Ouchi Mai , Osonoi Yumi , Mukai Hitoshi , Machida Toshinobu , Sugawara Hirofumi , Kaneyasu Naoki , Niwa Yosuke
Published: March 2020

The Grater Tokyo Area is the most populated (38 million) metropolitan area in the world. To capture fossil fuel carbon dioxide (CO2) emissions from the Grater Tokyo Area, we performed ground-based atmospheric observations for measuring concentrations of CO2, radiocarbon in CO2 (14CO2), oxygen (O2) and carbon monoxide (CO) at Tokyo Skytree (TST, with high altitude (250m) inlet) and Yoyogi (YYG, turbulentCO2 flux measurement site located in resident area) in Tokyo and at National Institute for Environmental Studies (NIES, suburb/rural area) in Ibaraki, Japan. The 14CO2 measurement was used for separating the fossil fuel CO2 emissions from the biotic emissions. Results from 14CO2 measurements showed that a ratio of fossil fuel-derived CO2 to the variation of CO2 concentrations was 71% in average for winter both at TST and YYG but varied from 44% to 92%, indicating significant contribution of biotic CO2 in Tokyo. The O2:CO2 exchange ratio (oxidation ratio, OR) was used for the partitioning of CO2 into emissions from gas fuels and gasoline. We observed larger OR in winter than in summer (due to both wintertime increases of fossil fuel combustion and summertime terrestrial biospheric activities) at TST and YYG and larger OR in the morning and late evening in winter due to increase of gas fuel combustion at YYG. We showed that the O2 concentrations might be also used as a proxy for continuous monitoring of fossil fuel CO2 content by assuming typical ratio of gas fuels and gasoline combustions. The presenter will introduce the related projects including development of building/road-scale dynamic CO2 mapping and grid-based CO2 emission inventory with high special resolution in Tokyo.
Targeted observations based on identified sensitive areas by CNOP to improve the thermal structures prediction in the summer Yellow Sea: preparatory work for the campaign in the field
Authors: Liu Jingyi , Guo Wuhong , Cui Baolong , Liu Kun , Hu Huiqin
Published: March 2020

Targeted observation is an appealing procedure to improve oceanic model predictions by taking additional assimilation of collected measurements. However, studies on targeted observation in the oceanic field have been largely based on modeling efforts, and there is a need for field validating observations. Here, we report the preparatory work of a field campaign, which is designed based on the identified sensitive area by the Conditional Nonlinear Optimal Perturbation (CNOP) approach, to improve the short-range summer thermal structures prediction in the Yellow Sea (YS). We firstly simulated the hindcasting (2016-2018) temperature structures in the summertime, and found that the locations of the sensitive areas are generally consistent in space for each hindcast year. Then, we introduced the technique of multiple-assimilation and the definition of time-varying sensitive area, and designed observing strategies for the YS summer campaign. Observing System Simulation Experiments (OSSEs) were conducted prior to address the plan on field campaign in the Yellow Sea in August 2019. Results show that, reducing the initial errors in the sensitive area can lead to more improvement on thermal structures prediction than that in other area.
Magnetic fabric and flow directions in magmatic rocks of the Franz Josef Land, Arctic Ocean
Authors: Chernova Anna , Abashev Viktor , Metelkin Dmitry , Vernikovsky Valery , Mikhaltsov Nikolay
Published: March 2020

Here, we present the results of a study of the anisotropy of magnetic susceptibility (AMS) completed in the Early Cretaceous magmatic complexes from the Franz Josef Land (FJL). AMS was measured in the framework of paleomagnetic research as a leading indicator of the rock magnetic fabric to help in understanding the lava flow directions and forming mechanisms. The three types of magmatic bodies were available in these studies: dolerite sills, dykes and basaltic lava flows from several islands (Alexandra, Hall, Ziegler, Jackson and Heiss Islands) among FJL. During the experiments the different parameters of AMS ellipsoids were obtained which have a good correlation with the igneous body shapes and also could illustrate lava flows direction parameters. The degree of anisotropy P is 1.01-1.06 for most sites that is typical for the primary igneous magnetic fabric. The form factor T characterizing the shape of the AMS ellipsoids demonstrates both planar and linear magnetic fabric in studied magmatic bodies. What is remarkable the part of the dykes is characterized strictly oblate magnetic fabric and another dykes have the prolate AMS ellipsoids. The linear magnetic structure is also more typical for lava flows with the maximum axes K1 lying in the flow plane that is obviously could point to the flow direction. The part of the igneous bodies are characterized by the inverse type of magnetic fabric, when the principal axis K1 of the ellipsoid is oriented perpendicularly to the plane of the flow or the sill, that was likely caused by the effect of secondary processes. The previous studies (Abashev et al., 2019) demonstrated that the primary orientation of the AMS ellipsoid could be recovered after temperature demagnetization. Noticeable changes were revealed at heating up to ~450 deg C, which generally corresponds to deblocking temperatures of titanomagnetites identified in the rocks by rock-magnetic methods. The degree of anisotropy was decreased after heating in 2-3 times. The heating also resulted to the redistribution of magnetic axes and in several cases the axes becomes more grouped. Analysis of the AMS results from the basaltic lava flows of the Aleksandra Island defined the magma flow direction to be NW-SE. Similar behavior of the AMS ellipsoids and lava flow orientation is typical for Ziegler Island. Generally our results show that complex analysis of AMS data in basaltic rocks is promising for identifying magma flow direction and it can give more detailed information about forming mechanisms of the different magmatic bodies.

This work was supported by the RSF (project no. 19-17-00091) and the RFBR (project nos. 18-35-00273, 18-05-70035).
An integrated approach for Territorial Spatial Planning Towards to Sustainable Urban Ecosystem Management: A Case Study of Yantai City
Authors: Wang Jing , Fang Ying ,   Jing Wang
Published: March 2020

 With the rapid urbanization, the most challenges have been faced with the accelerated degradation of habitat quality and increasing ecological risks for urban natural ecosystems. It is important to explore an integrated approach for territorial spatial planning towards to sustainable urban ecosystem management for directing programs of natural ecosystems conservation and restoration toward preserving the most valuable natural resources. In the study, Yantai city in Shangdong province in China was as an example. The goal, method and spatial boundary of territorial spatial planning towards to sustainable urban ecosystem management were clarified. A technical framework of urban territorial spatial planning and an integrated approach to determine key areas of ecosystem preservation and restoration were proposed. The results showed that the application of urban territorial spatial planning in Yantai was feasible and effective and provided new ideas and methods for the territorial spatial planning. The ecological network pattern by the “two horizontal and two vertical” spatial pattern was proposed. Key areas of ecosystems conservation and restoration were identified, including 13 ecological pinch points, 8 ecological barrier points, 39 ecological break points, and 1308.66 km2 fragmented ecological land. Natural solutions and measures for key areas of ecosystems conservation and restoration were proposed. It would help to provide scientific guidance for urban spatial planning toward to sustainable ecosystem management.
Measurement of VOCs using open-path mid-infrared dual comb spectroscopy
Authors: Cossel Kevin , Waxman Eleanor , Giorgetta Fabrizio , Baumann Esther , Friedlein Jacob , Herman Daniel , Ycas Gabriel , Coddington Ian , Newbury Nathan
Published: March 2020

Open-path measurements of atmospheric gas species over km-scale path lengths are well suited to quantify emissions from sources like oil and gas, forest fires, and industry. is a relatively new technique that combines high-resolution and broad spectral coverage with no instrument lineshape and near perfect frequency calibration. These features have enabled open-path DCS to provide accurate measurements of multiple trace gas species simultaneously in the near-infrared across path lengths ranging from 100 m to several km. However, in order to reach the sensitivity necessary to detect many atmospheric trace constituents, including volatile organic compounds (VOCs), operation in the mid-infrared (or UV/Vis) is required.

Here, we show a mid-infrared open-path dual comb spectrometer operating in the 3-4 and 4.5-5 μm spectral regions. We have used this spectrometer to measure methane, ethane, and propane (arising primarily from oil and gas activity) across a 1-km-long path in Boulder, CO for 1 week with an ethane sensitivity of ∼0.1 ppb for a 2-minute time resolution. In addition, we show quantitative measurements of intentionally released acetone and isopropanol with a 1-σ sensitivity of 5.7 ppm·m and 2.4 ppm·m, respectively. In the 4.5-5 μm region, we have used this system to detect N2O, CO, and O3. Finally, we have developed a second-generation instrument in the 3-4 μm region that is more compact and has improved stability. This system was recently deployed in a van at an active oil and gas drilling operation. We present preliminary measurements of methane, ethane, and higher hydrocarbons from this deployment as well as initial efforts at emissions quantification.
The response of VLF signals to the passage of an atmospheric/ionospheric seismic wave after an earthquake in Chile
Authors: Yusupov Kamil , Alexander Rozhnoi , Maria Solovieva , Sergey Shalimov , Viktor Fedun , John Mathews , Ruslan Sherstyukov , Anvar Safiullin , Takashi Maruyama
Published: March 2020

Natural disasters, such as earthquakes, tsunamis, volcanic eruptions, tropical cyclones (typhoons in the Pacific, hurricanes in America), often lead to enormous human casualties, causing great damage to the human environment. This is due to the unpredictable nature of disasters. Investigation of the precursor signs of the development of such dangerous events (including an assessment of their power) allows you to inform the relevant services in advance of a natural disaster. This is often a very urgent task. The experimental and theoretical study of the electromagnetic response of the ionosphere to the development of natural catastrophic events is an important component of furthering disaster preparedness. This includes improvement of methods for event precursor isolation for use in warning and development systems. In this, validation of lithosphere-ionosphere communication models are very important. Therefore, in this work, we consider the amplitude anomalies of VLF signals recorded at a station in Moscow (Russia) during the passage of an atmospheric/ionospheric seismic wave from an earthquake in Chile, which epicenter is removed at a distance of ~ 15 thousand km.

The work is performed according to the Russian Government Program of Competitive Growth of Kazan Federal University.
Assessment of the risk of destabilization of vehicles at crossing points between streams and roads
Authors: Bocanegra Vinasco Ricardo Andres , Francés Félix
Published: March 2020

River floods can cause the destabilization of vehicles and vehicles can increase the negative impacts of floods when they are mobilized by the flow, causing economic and life losses. Because of this, integral flood management requires the identification and assessment of the risk to which vehicles are subjected at the crossing points between water currents and roads. In the present investigation a methodology was developed to calculate this risk based on the characteristics of vehicles, floods and traffic. The risk at each stream crossing is calculated by means of the statistical integral of the vehicle vulnerability given the actual exposition and hazard.

 

Hazard corresponds to the probability that flow causes the destabilization of each type of car and is determined from the hydrodynamic characteristics of the floods and the implementation of a stability criterion for partially submerged cars, through which a hazard index is established. Hazard is obtained through the combination of the probability that the flood event occurs with the values that the hazard index would take. The vulnerability of a given type of car is determined by means of a damage function defined from the values of the hazard index. The exposure is established based on the traffic characteristics and the driver behavior.

 

The methodology developed was applied in the municipality of Godelleta (Spain), finding that in approximately a quarter of the 25 intersections between streams and roads, the risk of vehicles due to flooding is relatively high, since it exceeds 0.2 vehicles per year. In approximately half of the intersections the risk is relatively low since it is less than 0.1 vehicles per year. Additionally, it was found that the risk of vehicles in stream crossings due to flooding is highly sensitive to the magnitude of the water level from which drivers decide to interrupt vehicle traffic through flooded crossing. The magnitude of the risk grows as drivers assume less conservative behavior, that is, when they decide to drive with higher water levels.

Key words

Risk of vehicles due to floods

Stability of cars partially submerged

Vulnerability of vehicles to floods
Numerical Model of the 1771 Meiwa tsunami and the influence of the reef
Authors: Le Gal Marine , Mitarai Satoshi
Published: March 2020

In 1771, a major tsunami event hit the Yaeyama Islands (Japan) and particularly Ishigaki Island, where 30m run-ups were estimated. As with many other Pacific Islands, Ishigaki Island is surrounded by a reef. Interactions between tsunami waves and reefs have generally been analyzed with idealized models and studies focusing on a specific reef are rare. It has been shown that the influence of the reef is two-fold : it can either amplify or buffer waves. For the particular 1771 event, this influence is still unknown and the present study aims to identify it. Several numerical models were developed using the 2D Nonlinear Shallow Water model of the Telemac system. First, a reference model was build, simulating the real event with an accurate reef representation. Then, altered bathymetry models were generated and compared to the reference model. In our simulations, overall, the reef protected the coast with a 12,5% decrease of the water depth at the shoreline. However channels, disrupting the continuity of the reef, strongly amplified inundations on the nearby coast, with up to 40% increase of the water depth at the shoreline. To go further, this results could provide inside to better manage the coast for future events.
Investigation of the response of water isotope records to the changes in orbital forcing with the isotope-enabled AGCM MIROC5-iso
Authors: Kino Kanon , Okazaki Atsushi , Cauquoin Alexandre , Yosnimura Kei
Published: March 2020

It has been well demonstrated that the variations of orbital parameters, known as Milankovitch theory, are one of the most important drivers of the Earth’s climate system. However, the way how the changes in orbital forcing imprint the glacial-interglacial cycles recorded in paleo-proxies, such as stable water isotopes in ice cores and speleothems, is still unclear. One way to progress in this question is to make direct comparisons of isotopic data with simulation results from isotope-enabled General Circulation Models (GCMs). We use here such a model, the Japanese atmospheric GCM MIROC5-iso[1], to perform simulations under different idealized paleoclimate conditions. For that, corresponding orbital parameters and greenhouse gases concentrations are set. Prescribed sea surface temperature and sea ice coverage boundary conditions from the fully coupled atmosphere-ocean GCM MIROC (MIROC-AOGCM) experiments are used, after an adaptation to the MIROC5-iso grid. Because earlier version of MIROC-AOGCM has been widely used for paleoclimate modeling purposes, the climatological mean states of MIROC5-iso under preindustrial conditions are evaluated against simulation results from different versions of MIROC-AOGCM (MIROC4m, which is a slightly updated version of MIROC3.2(med), and MIROC5 [2]). In addition, several interglacial periods and idealized paleoclimate experiments will be investigated and implications for the interpretation of water isotope response to the changes in orbital forcing will be discussed.

[1] Okazaki and Yoshimura, J. Geophys. Res. Atmos, 124, 8972–8993, 2019.

[2] Watanabe et al., J. Climate, 23, 6312–6335, 2010.