bluuebunny/crossref_metadata_2025 huggingface dataset:
Prospective upscaling of quantification of non-rainfall water inputs to regional scale
Authors: Agam Nurit , Kool Dilia
Published: March 2020

In drylands, the annual amount of non-rainfall water inputs (NRWIs), i.e., a gain of water to the surface soil layer that is not caused by rainfall, can exceed that of rainfall.  They thus significantly contribute to the water cycle and to biogeochemical dynamics.  However, the small magnitude of the fluxes involved in the formation and evaporation of NRWIs challenges their measurement.  Various methods were applied in attempting to quantify NRWIs amount and duration, all being point/local measurements.  Given the large heterogeneity of soils, both at local and at regional scale, upscaling from the small point measurement methods to larger scales is necessary in order to fully understand the environmental factors controlling NRWIs and the role of NRWIs in dryland ecosystems.  Numerous remote sensing-based models have been developed to assess spatially distributed latent heat fluxes, greatly varying in complexity.  Unfortunately, the magnitude of diurnal fluxes due to NRWIs is too small to be detected by any of the existing models.  Hypothesizing that soil surface emissivity is sensitive to very small changes in water content at the top soil layer, our objective was to quantify NRWIs by analyzing the temporal changes in land surface emissivity over bare loess soil in the Negev desert, Israel.  Proven successful, this can be utilized over large areas. 

Intensive measurements using a longwave infrared radiometer (CLIMAT 312-2n ASTER, Cimel Electronique, Paris, France) were conducted in summer 2019 at the Wadi Mashash Experimental Farm (31o08’N, 34o53’E).  Radiance and temperature measurements were obtained for a broad band (8.01-13.34 μm) and 5 subsections of this bandwidth.  The radiometer was mounted at 0.5 m directly above one of four microlysimeters (undisturbed soil samples installed flash with the soil surface and weighed continuously).  Radiometer readings were automatically taken every 15 min for 24-h cycles. 

Initial results indicate an agreement between the diurnal cycle of NRWIs detected by the microlysimeters and between the diurnal cycle of an index derived from the radiometer bands: (e11.3-e8.3)/ e10.6 (the numbers are the center of the band in µm).  These preliminary results show the potential to upscale quantifying NRWIs to regional scale.
Spatial-temporal variation assessment of the water quality in the Baiyangdian Lake of North China for the period of 2006 to 2016
Authors: Quan Han , Wenchao Sun , Zhanjie Li
Published: March 2020

Baiyangdian Lake is the largest freshwater lake in the North China Plain. In order to examine the driving mechanisms of changes on the lake’s water quality, an improved Water Quality Index (WQI) method and multivariate statistical techniques were applied to analyze water quality in this study. Water quality data from six monitoring stations for the period of 2006 to 2016 were used. The calculation of the annual WQI indicated an improvement in lake’s water quality over the past decade. Cluster analysis classified 12 months and the six monitoring stations into two clusters (dry-wet period and western-eastern part), respectively. Discriminant analysis provided fewer effective variable with only two parameters and six parameters to afford 96.0% and 93.8% correct assignations in the temporal and spatial clusters. Principal component analysis and factor analysis detected similar varifactors in the two temporal clusters, interpreting more variance related human activities in the water quality variation than the ones representing natural factors. The different varifactors related to pollution source were evaluated in the two spatial clusters. The result indicated water quality in the two regions are influenced by different types of anthropogenic activities. Our findings provide valuable information for decision-making related to pollution control, ecosystem restoration, and water resource management in Baiyangdian Lake, as well as other large, shallow lakes in high-intensity hu+man activities regions.
Spatiotemporal Variability of Potential Evaporation in Heihe River Basin Influenced by Irrigation
Authors: Han Congying
Published: March 2020

Spatiotemporal Variability of Potential Evaporation in Heihe River Basin Influenced by Irrigation

Congying Han1,2, Baozhong Zhang1,2, Songjun Han1,2

1 State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China.

2 National Center of Efficient Irrigation Engineering and Technology Research-Beijing, Beijing 100048, China.

Corresponding author: Baozhong Zhang (zhangbaozhong333@163.com)

Abstract: Potential evaporation is a key factor in crop water requirement estimation and agricultural water resource planning. The spatial pattern and temporal changes of potential evaporation calculated by Penman equation (EPen) (1970-2017) in Heihe River Basin (HRB), Northwest China were evaluated by using data from 10 meteorological stations, with a serious consideration of the influences of irrigation development. Results indicated that the spatial pattern of annual EPen in HRB was significantly different, among which the EPen of agricultural sites (average between 1154 mm and 1333 mm) was significantly higher than that of natural sites (average between 794 mm and 899 mm). Besides, the coefficient of spatial variation of the aerodynamic term (Eaero) was 0.4, while that of the radiation term (Erad) was 0.09. The agricultural irrigation water withdrawal increased annually before 2000, but decreased significantly after 2000 which was influenced by the agricultural development and the water policy. Coincidentally, the annual variation of Epen in agricultural sites decreased at -40 mm/decade in 1970-2000 but increased at 60 mm/decade in 2001-2017, while that in natural sites with little influence of irrigation, only decreased at -0.5mm/decade in 1970-2000 but increased at 11 mm/decade in 2001-2017. So it was obvious that irrigation influenced Epen significantly and the change of Epen was mainly caused by the aerodynamic term. The analysis of the main meteorological factors that affect Epen showed that wind speed had the greatest impact on Epen of agricultural sites, followed by relative humidity and average temperature, while the meteorological factors that had the greatest impact on Epen of natural sites were maximum temperature, followed by wind speed and relative humidity.
Spatio-temporal characteristics and focal mechanisms of deep low-frequency earthquakes beneath Zao volcano, Japan
Authors: Ikegaya Takuma , Yamamoto Mare
Published: March 2020

Deep Low-Frequency earthquakes (DLFs) beneath volcanoes are possible evidence for deep-seated magmatic activities in the crust and uppermost mantle. After the 2011 Tohoku Earthquake (Mw 9.0), the number of DLFs beneath Zao volcano in the northeast Japan started increasing. The hypocenters of these DLFs form two clusters at shallow (20~28 km) and deep (28~38 km) depths. The shallow and deep clusters are located central and lower part of a high Vp/Vs zone, respectively (e.g., Okada et al., 2015), and the fact suggests different fluid involvement and source processes of DLFs at two clusters. In addition, after the activation of DLFs in 2012, increase in shallow ( < 2 km depth) seismicity has been observed since 2013, which implies the interaction of shallow and deep volcanic fluids. However, the small magnitude of DLFs makes it rather difficult to discuss detailed spatio-temporal characteristics of DLFs and focal mechanism of individual DLF. Therefore, in this study, we first detected DLFs using waveform correlation and determine their hypocenter, and then classified DLFs using waveform correlation to reveal the spatio-temporal characteristics and focal mechanism of each event type.

To detect DLFs, we applied the matched filter method to the continuous three-components waveform data recorded at stations operated by Tohoku Univ., NIED, and JMA. 146 DLFs listed in the JMA unified earthquake catalog between Jan. 2012 and Sept. 2016 were selected as templates. For each newly detected DLF, we estimated the differential arrival times using cross-correlation between the detected DLF and the template having maximum correlation, and determined the relative hypocenter using the master event method. As a result, we determined hypocenters of 1202 DLFs between Jan. 2012 to May 2018, which is about 4 times the number of DLFs listed in the JMA catalog.

We then classified newly detected DLFs using the hierarchical clustering method based on the waveform correlation, and classified 939 events into seven types (Type A: 241 events, B: 222, C: 295, D: 79, E: 42, F: 37, G: 23). The characteristics of individual waveform types are summarized as follows: Type C shows high frequency components (4-8 Hz) superimposed on the P wave, while the other types only have low frequency components (1-4 Hz); S-wave/P-wave spectral ratio of type C observed at each station shows larger azimuthal variation than that of the other types, and shows maximum peaks in northeast and southwest direction; Type C occurs mainly in the deep cluster while the other types occur in the shallow cluster; The activity of type C started in 2012 and showed rapid increase in 2015, while the other types show similar temporal changes in 2013 and 2016.

These results of this study suggest fluid transportation in the crust and different dynamic processes at each depth beneath the volcano.
Phase velocity of internal solitary waves in the Dongsha region of the northern South China Sea
Authors: Kuang Yunyan , Song Haibin , Guan Yongxian , Fan Wenhao , Gong Yi , Zhang Kun
Published: March 2020

Phase velocity is a fundamental parameter to characterize internal solitary waves(ISW) dynamics. Seismic oceanography method to derive the phase velocity of internal solitary waves has been reported recently. In addition, seismic oceanography data can be used to image the internal solitary waves  and extract ISW’s vertical structure. In this paper, we study the relation between ISW phase velocities with wave amplitude and corresponding water depths based on lots of seismic oceanography data in the Dongsha region of the northern South China Sea.

A seismic survey cruise was carried out on Dongsha Plateau in the summer of 2009. We used Seismic Unix to reprocess the seismic dataset. Our process method can image the water column below 50m. We identify 8 single depression solitons , 4 ISW packets on the shelf and upper continental slope. We extracted phase velocities, corresponding water depths and maximum wave amplitudes of these ISWs. The result shows that phase velocities are positively correlated both with wave amplitude and water depths. We obtain one relation formula between ISW phase velocities with wave amplitude and corresponding water depths by linear regression fitting.  Then we have a detailed discussion on ISWs features in the Dongsha region.
Drying Tendency over the Southern Tibetan Plateau in Recent Past Decades
Authors: Wang Ziqian , Yang Song , Duan Anmin
Published: March 2020

The Tibetan Plateau (TP) exerts a significant impact on the weather and climate over many places of the world through both mechanical and thermal-dynamical effects. In summer, the major rainfall of the TP occurs over the southern slope, and the associated atmospheric latent heating dominates the total diabatic heating of TP. Then the variation of summer rainfall can directly regulate the TP’s thermal effects. On the other hand, the rainfall center over the southern slope is corresponding with the northern branch of South Asian summer monsoon, which is important to the agricultural productivity and economic stability along the Ganges River with dense population. This study shows that there existed a drying tendency over the southern TP (STP) in the rainy season of recent decades. A moisture budget analysis indicates that the dynamic change in vertical moisture advection is the dominant contributor to the drying trend, which is associated with the weakened upward motion over the STP. The changes in dynamic process over STP are induced by the northward shift of the subtropical westerly jet, whose northward shift reduces the upper-level anticyclone over STP and weakens the upper-level divergence, leading to a trend of vertical sinking motion. Furthermore, the northward shift of the jet is mainly attributed to the internal variability of the atmosphere, characterized by an upper-level circum-global wave train. The influence of atmospheric internal variability is demonstrated by the CESM Large Ensemble Project data.
Verifying methane emission estimates from agricultural regions in Eastern Ontario using TROPOMI product
Authors: Liu Jiangui , Desjardins Ray , VanderZaag Andrew , Worthy Douglas , worth Devon
Published: March 2020

The two main sources of CH4 from the agricultural sector are enteric fermentation and manure management systems. Canada uses the IPCC Tier-II methodology to estimate CH4 for its national inventory report of GHG emissions to UNFCCC, which is based on a bottom-up approach using activity data and emission factors obtained through site level experimental measurements. However, because of the presence of wetlands in some agricultural regions, it has been challenging to obtain accurate CH4 emission estimates at a regional scale.

This study explores the usefulness of S5P methane product for verifying methane emission estimates in eastern Ontario agricultural land. We investigated the spatiotemporal variability of total column methane mixing ratio, as well as other detailed data layers in the TROPOMI product, such as averaging kernels and a prior profiles. The spatial temporal patterns of wetland methane emission derived from the global WetCHARTs dataset, and a prior knowledge of livestock distribution in the region, are used to interpret S5P methane product. Results showed that TROPOMI methane product provides great spatiotemporal coverage that can be used to verify CH4 emissions from agricultural landscape. This will be useful to reduce methane estimation uncertainties at the regional and national scales.
Non-lithostatic eclogitization in exhuming continental crust
Authors: Cutts Jamie , Smit Matthijs , Vrijmoed Johannes
Published: March 2020

During collisional orogeny, the lower continental plate is typically subjected to pressures no greater than 3 GPa (~100 km). Locally, however, ultrahigh-pressures (UHP) in excess of 5 GPa have been recorded, most commonly in included metamorphosed mafic-ultramafic rocks. Such pressures would suggest burial of continental crust to mantle depths; however, continental subduction to such depths is not observed in active orogens as it is hindered by the positive buoyancy of sialic crust relative to the mantle. An alternative explanation for extreme pressures recorded in continental crust is that they reflect non-lithostatic conditions, an idea that has been limited to modelling experiments and thus its applicability to natural systems is highly debated. Specifically, it was proposed that mechanical heterogeneities could explain extreme non-lithostatic pressures of c. 5.5 GPa obtained in enstatite eclogite veins cross-cutting a peridotite hosted in the archetypal subducted continental terrane, the Western Gneiss Complex (WGC) in Norway. Here, we use thermobarometry and Lu-Hf garnet geochronology to determine at what conditions and at what point in the burial cycle the enstatite eclogite assemblages actually equilibrated. The results show that the enstatite eclogites equilibrated at pressures of 4-5.5 GPa and at c. 393 Ma; these conditions are greater than those typical of ‘normal’ eclogites in the WGC and the age represents a time when the terrane had already exhumed to crustal depths (<2.5 GPa). Finite element modeling of mechanical pressure distribution can explain the seemingly spurious conditions recorded in these unusual rocks and demonstrates that these late extreme pressure excursions are feasible for the given rock system. Although the occurrence of non-lithostatic UHP conditions in deeply buried continental crust may, indeed, be unusual, it allows crucial simplification of models for continental subduction and validates the importance of integrating rock thermo-mechanics with geochronology and thermobarometry in interpreting observations from collision zones.
Estimating Downcore Decline in Skeletal Disintegration Risk in Holocene Environments
Authors: Hohmann Niklas , Tomašových Adam
Published: March 2020

Preservation of skeletal remains is thought to be positively linked to rate of burial, i.e., they are exposed to destructive processes for a shorter time under higher burial. However, downcore changes in time-averaging documented in Holocene skeletal assemblages implies that per-individual burial rates of skeletal remains of the same age cohort can be variable, e.g., owing to bioturbation, and estimation of time (and sediment depth) over which skeletal remains are exposed to destruction is not straightforward.

This variability in the depth of burial exposes them to different intensities of destructive processes that is typically highest in sediments on or close to the seafloor, and accordingly changes their probability of disintegration. This hinders both the reconstruction of taphonomic conditions downcore and the reconstruction of biological archives from age cohorts of skeletal remains.

We present the AALPS (Aging ALong burial PathS) model to estimate downcore disintegration risk and taphonomic age, based on sediment-depth distribution of postmortem age of individual skeletal remains. This model can be applied to individual cores and taxa, accounts for sediment mixing and time-averaging, and incorporates knowledge of changing sediment input.

As an application, we discriminate between distinct hypotheses of changes in skeletal disintegration rates in cores from the Adriatic Sea.

The method provides new insights into the taphonomy of skeletal remains in Holocene and Anthropocene environments and age unmixing of paleoecological time series, which can be used in conservation paleobiology to reconstruct ecological baselines to guide future conservation efforts.
Seasonal and regional temperature differences in subtropical China during the past 200 years
Authors: Cai Qiufang , Liu Yu
Published: March 2020

Tree ring plays an important role in deciphering the paleoclimatic signals over the past 100-10000 years. However, tree-ring studies from tropical to subtropical regions are rarer than that from extratropical regions, which greatly limit our understanding of some critical climate change issues. Based on tree-ring-width chronologies in different area of Subtropical China (SC), seasonal temperature history of different seasons over the past 200 years were reconstructed. In addition to the warm and cold fluctuations in the reconstructed temperature series, main conclusions are drawn in the following two aspects: 1) Winter-half year temperature had good agreement with summer-time temperature variation in SC at decadal scale, while the winter-half year warming in recent decades was more evident than summer-time. 2) Comparison of the tree-ring based temperature series indicated that the start time of the recent warming in eastern China was regional different. It delayed gradually from north to south, starting at least around 1940 AD in the north part, around 1970 AD in the central part and around 1980s in the south part.
Accuracy Validation of Flood Forecasting Method Based on Time Series Analysis Using Observed Water Level and Rainfall Data
Authors: Koyama Naoki , Yamada Tadashi
Published: March 2020

The aim of this paper is to verify the accuracy of the real-time flood prediction model, using the time-series analysis. Forecast information of water level is important information that encourages residents to evacuate. Generally, flood forecasting is conducted by using runoff analysis. However, in developing countries, there are not enough hydrological data in a basin. Therefore, this study assumes where poor hydrologic data basin and evaluates it through reproducibility and prediction by using time series analysis which statistical model with the water level data and rainfall data. The model is applied to the one catchment of the upper Tone River basin, one of the first grade river in Japan. This method is possible to reproduce hydrograph, if the observation stations exist several points in the basin. And using the estimated parameters from past flood events, we can apply this method to predict the water level until the flood concentration time which the reference point and observation station. And until this time, the peak water level can be predicted with the accuracy of several 10cm. Prediction can be performed using only water level data, but by adding rainfall data, prediction can be performed for a longer time.
The impact of the rotational direction of a wind turbine on its wake
Authors: Englberger Antonia , Dörnbrack Andreas , Lundquist Julie
Published: March 2020

Wind turbines operating in a stably stratified atmospheric boundary layer often interact with a veering wind, which is characterized by a clockwise wind direction change with height in the Northern Hemisphere. The rotational direction of the wind turbine rotor has a significant impact on the flow field in the wake in case of a veering wind, whereas it is of minor importance if the wind direction is the same over the whole rotor.

The impact of the rotational direction in a stably stratified atmospheric boundary layer results in contrasting rotational directions of the near and far wake in case of a common clockwise rotating rotor, whereas in case of a counterclockwise rotating rotor the rotational direction of the wake persists in the whole wake. The change of the rotational direction of the wake at a downstream location, which is related to the transition from the near wake to the far wake region, results in a larger streamwise wake elongation and a narrower spanwise wake width. In the lower and upper part, the wake deflection angle is also influenced by the rotational direction of the blades, resulting in a smaller wake deflection angle in case of a common clockwise rotating rotor in the Northern Hemisphere. In the Southern Hemisphere, the situation is reversed, an effect related to the Coriolis force impact on the Ekman spiral.

As the rotational direction impacts the inflow velocity, it effects the produced power of a downwind turbine and likewise the loads acting on a downwind turbine. For a hypothetical downwind turbine with a staggered spacing of 7 D, the power output difference would be up to 23% in idealized simulations, whereas the power output difference for a counterclockwise rotating rotor instead of a clockwise one also depends on atmospheric conditions like the strength of stratification, the strength of the veering wind, the rotor fraction impacted by a veering wind, and wind speed.
Formation and succession of microbial community structure in different ecological niches under reclaimed water acclimation
Authors: Li Jie , Sun Yujiao , Wang Xiaoyu , Yin Meng , Xu Shangwei
Published: March 2020

Using reclaimed water as a resource for landscape water replenishment may alleviate the major problems of water resource shortages and water environment pollution. However, the safety of the water and the risk of eutrophication remain doubted by the public. Our study aimed to reveal the difference between natural water and reclaimed water and to discuss the rationality of reclaimed water replenishment from the perspective of microorganisms. We analyzed the microbial community structures in natural water, reclaimed water and natural biofilms and the community succession was clarified along the ecological niches, water resources, liquidity and time using 16S rRNA gene amplicon sequencing. Primary biofilms without the original community were added to study the formation of microbial community structures under reclaimed water acclimation. The results showed that the difference caused by ecological niches was more than those caused by the liquidity of water and different water resources. No significant difference was found in the microbial diversity and community structure caused by the addition of reclaimed water. Based on the microbial analysis, reclaimed water replenishment is a feasible solution that can be used for supplying river water. Innovatively, we introduced the study of biofilms and determined that the monitoring of biofilms or sediments closely related to water was also important for the early warning of water bloom, providing a unique perspective for the management of eutrophication.
Travels with an EM27, measurements of CO2 and CH4 below 45 degrees south.
Authors: Pollard David F. , Smale Dan , Tran Hue , McGaw Jamie , Hase Frank , Blumenstock Thomas
Published: March 2020

During 2016 and again during 2019 through 2020 an EM27/SUN portable near infrared solar absorption Fourier Transform Spectrometer of the Karlsruhe Institute of Technology was transported first to Lauder, New Zealand (45.034S, 169.68E, alt. 370 m) and then to the Arrival Heights laboratory, Ross Island Antarctica (77.82S, 166.65E, 200 m). On the first occasion the EM27/SUN made the first ever near infrared solar absorption retrievals of carbon dioxide and methane in Antarctica over a period of two weeks. The second deployment had the aim of making retrievals in Antarctica throughout the 2019-2020 Austral summer.

We report on the comparison of retrievals of carbon dioxide and methane from the EM27 spectra with those made by the Total Carbon Column Observing Network (TCCON) stations at both Karlsruhe and Lauder and compare with similar comparisons made throughout the Collaborative Carbon Column Observing Network (COCCON), as well as the latitudinal extension of these measurements to Antarctica.

Further comparisons with observations from TROPOMI instrument on the Sentinel 5 precursor satellite will be discussed.
Different responses of groundwater level changes through hydrogeological characteristics due to M5.4 Pohang earthquake
Authors: Lee Soo-Hyoung , Lee Jae Min , Yoon Heesung , Kim Yongje
Published: March 2020

Earthquake of magnitude M5.4 the second largest recorded earthquake occurred in Pohang, South Korea at 05:29:32 (UTC time) on November 15, 2017. The M5.4 event and hundreds of aftershocks produced extreme impacts across the area to date along with human and property damages. The distance between the epicenter of the M5.4 Pohang earthquake and the groundwater observation well is about 43 km for KJ-well and about 76 km for YS-well. Records from these two monitoring wells showed groundwater level changes occurred in 2017-11-15 05:30 (UTC time), about 30 seconds after the earthquake. In KJ-well, 8.0 cm of groundwater level change was observed, and in YS-well, about 30.0 cm of groundwater level change. The changes in groundwater level appeared to be a spike-like pattern that rises immediately due to the compressive action of the aquifer as the seismic waves pass through and then return to its original state. Interestingly, the groundwater level changes in YS-well was observed to be approximately three times greater than KJ-well although YS-well is approximately twice as far from the epicenter as KJ-well. The factors causing these different changes were compared and analyzed for the geometry, hydraulic properties, and geological characteristics of the well locations
Low Dinitrogen Fixation Rates in the Bay of Bengal during Summer Monsoon
Authors: Singh Arvind , Saxena Himanshu , Sahoo Deepika , Khan Mohammad Atif , Kumar Sanjeev , Sudheer Athiyarath K
Published: March 2020

Nitrogen is a staple element for every living organism in addition to carbon, since all the major cellular components (e.g., DNA and RNA), proteins, and energy carrier molecules (e.g., ATP) are stemmed from these elements. Biological dinitrogen (N2) fixation exerts an important control on oceanic primary production by providing bioavailable form of nitrogen (such as NH4+) to photosynthetic microorganisms. We hypothesized that the oligotrophic nature of the Bay of Bengal might create a suitable niche for N2 fixing microorganisms.

In the Bay of Bengal, fresh water influx driven stratification prevent the vertical influx of nutrients to the sunlit layers. Most of the riverine nutrients are used within estuarine and coastal regions, and thus these have negligible contribution on open ocean biological productivity. Atmospheric deposition contribution to the nutrients supply is equally low (< 3%) in the Bay. Thus, the recently observed high new production rates in the Bay of Bengal suggests the higher probability of N2 fixation in this basin than the Arabian Sea. In addition, nitrogen isotopic composition of sedimentary organic matter (low δ15N values) in the Bay of Bengal can also be alluded to the presence of diazotrophy in the Bay. Hence, we further strengthened our hypothesis that N2 fixers play a crucial role for the primary production in the Bay.

We commenced the first N2 fixation study in the sunlit layer of the Bay of Bengal using 15N2 gas tracer incubation experiments on a cruise expedition during summer monsoon 2018. N2 fixation rates varied from 4 to 124 μmol N m-2 d-1 – these rates were very low compared to that observed in the Bay’s western counterpart in the Indian Ocean, i.e., the Arabian Sea. The contribution of N2 fixation to primary production was small (< 1%). Noteworthily, the upper bound of observed N2 fixation rates in our study was still higher than that measured in other oceanic regimes such as Eastern Tropical South Pacific, Tropical Northwest Atlantic, and Equatorial and Southern Indian Ocean. Strong monsoonal winds, turbidity due to copious riverine discharge and cloud cover over the Bay of Bengal might have inhibited N2 fixation. Therefore, a more detailed study covering all the seasons is needed to understand the role of N2 fixation rates on primary productivity in the Bay of Bengal.
An International Cooperation Practice on the Analysis of Carbon Satellites data
Authors: Zhang Lianchong , Li Guoqinng , Zhao Jing , Li Jing
Published: March 2020

Carbon satellite data is an essential part of the greenhouse observation and plays a critical role in global climate change assessment. Existing carbon data analysis e-science platforms are affected by restrictions in distributed resource management and tightly coupled service interoperability. These barriers currently offer no support for facilitating cross-disciplinary exploration and application,which have hindered the development of international cooperation. From 2018, the Cooperation on the Analysis of carbon SAtellites data (CASA), a new international scientific programme, was approved by the Chinese Academy of Sciences (CAS). So far, more than 9 research institutions have been integrated under this cooperation. The result is demonstrated in the global XCO2 dataset based on the Tansat satellite.
Application of passive and active seismic methods to subsurface investigation of Just-Tegoborze landslide (Outer Carpathians, Poland)
Authors: Harba Paulina , Krawiec Krzysztof
Published: March 2020

The study presents the results of seismic measurements on the Just-Tegoborze landslide located in Outer Carpathians in the southern region of Poland. The aim of the study was to investigate the landslide geological subsurface and define S-wave velocity changes within geological medium using passive seismic interferometry (SI) and active multichannel analysis of surface waves (MASW). Additionally, seismic refraction and numerical slip surface calculations were carried out in order to combine the results.

Measurements of SI were conducted based on local high-frequency seismic noise generated by heavy vehicles passing state road which intersects Just-Tegoborze landslide. Seismic noise registration was made using three-component broadband seismometers installed along a seismic profile. Measurements were repeated in a few series in different season and hydration conditions.

Seismic sections show different velocity layers within the landslide medium. Comparing them with geological cross-section of the studied area, we can distinguish the main lithological boundaries. First near-surface seismic layers may correspond to clayey colluvium and clayey-rock colluvium. The deepest seismic layer probably correlates to less weathered flysch bedrock made of shales and sandstones. It can be identified as the main slip surface of the studied landslide.

S-wave velocities within seismic profiles significantly varies between each measurement series of SI. It can be observed a decrease of S-wave velocity in March and July which is connected to seasonal weather and hydration conditions. Strong increase of hydration during melting snow cover in March and after heavy rainfalls in July resulted in loss of rigidity what presumably led to drop of S-wave velocity. Changes in hydration could also cause the variation of the course of the less weathered flysch bedrock boundary.

Presented results of passive seismic interferometry measurements show that study of seismic noise can be applicable to subsurface identification of an active landslide. The example of Just-Tegoborze site indicates that based on seismic interferometry it is possible to observe changes in elastic properties of geological medium. It is worth to underline that SI and MASW complement each other in retrieving the information of Rayleigh surface wave. Combining the results with seismic refraction and numerical calculations allows to better image the landslide geological subsurface. Such observations may be helpful in assessing landslide threat.
The effect of sky conditions and urban morphology on urban heat island in Seoul city
Authors: Joen Soo Joeng , oh Jin woo , Ngarambe Jack , Nzivugira Duhirwe Patrick , Aye Su Mi , Yun Geun Young
Published: March 2020

The urban heat island (UHI) is a serious climatological phenomenon that is likely to exacerbate the effects of climate change. It has adverse effects on the thermal comfort of urban dwellers, building energy consumption and the general health of vulnerable demographics (i.e. older people). To understand the effects of UHI and therefore devise efficient methods to mitigate it, it is important that we understand the many factors affecting UHI and the magnitude of their contribution on the manifestation of UHI, especially in urban areas. Consequently, in the current study, we study the effect of sky conditions and urban geometry on UHI in Seoul city, South Korea. The climatic data detailing diverse sky conditions, categorized by the amount of cloud cover, was collected from 28 Automatic Weather Stations (AWS) located in Seoul city. Information on urban geometry such as building density, gross floor area ration and building area ratio was obtained from satellite imagery. Our results indicate that the levels of UHI, quantified using urban heat island intensity (UHII), are dependent on the prevailing sky conditions. We found that, UHII was highest under cloudy sky conditions (r = 0.71) and lowest under clear sky conditions (r = 0.66). Furthermore, we found that UHII was correlated with building area ratio and gross area ratio; areas with high building area ratios and gross area ratios tended to also experience high UHII levels. The results presented in the current study are useful to policy makers or urban designers that wish to curb the increasing effects of UHI in urban areas and consequently improve thermal comfort in urban areas, reduce building energy consumption for space cooling purposes and prevent heat-related mortalities in old and vulnerable populations.

 

 
Land degradation risk mapping using novel machine learning algorithms
Authors: Torabi Haghighi Ali , Darabi Hamid , Karimidastenaei Zahra , Davudirad Ali Akbar , Rouzbeh Sajad , Sajedi Hosseini Farzaneh , Klöve Björn
Published: March 2020

Land degradation (LD) is a complex process affected by both anthropogenic and natural driving variables, and monitoring LD progression in areas under human‐induced stresses has become an essential task. In this study, we developed an approach for evaluating and mapping potential LD risks associated with human-induced and biophysical driving variables. We employed machine learning algorithms (Support Vector Machine (SVM), Multivariate Adaptive Regression Splines (MARS), Generalized Linear Model (GLM), and Dragonfly Algorithm (DA)) for LD risk mapping based on topographic (n=7), human-induced (n=5) and geo-environmental (n=6) variables and field measurements of degradation. The performance of different algorithms was assessed using receiver operating characteristic (ROC), Kappa index, and Taylor diagram. An urbanized watershed, Pole-doab in central Iran, was selected as the case study. The performance data indicated that DA (an novel optimized algorithm) was most accurate in LD risk mapping. In LD zone maps produced using SVM, GLM, MARS, and DA, 19.16%, 19.29%, 21.76%, and 22.40%, respectively, of total area in the Pole-doab watershed had a very high degradation risk. In all cases, the LD risk maps indicated that land in the southern part of the Pole-doab watershed is most exposed to degradation of different types.
Root exudate induced microbial activities and phosphorus cycling in soil: An application of phosphate oxygen isotopes
Authors: Joshi Sunendra R , McNear David H
Published: March 2020

Rhizosphere is the most biologically active region between the plant and the surrounding soil where plant release their fixed carbon into the soils. Depending on the availability and types of carbon compounds released from the plant, they can directly solubilize nutrient or indirectly influence nutrient cycling by promoting increased microbial activity in the rhizosphere. In this study we applied phosphate oxygen isotope ratios (d18OP) to determine how root exudate influences temporal variation in microbial activities and P cycling in the rhizosphere. Rhizoboxes were filled with soils, watered to 75% water holding capacity and equilibrated for 10 days. After equilibration labeled phosphate isotopes synthesized using 18O labeled water was applied. Then a mixed exudate (i.e., glucose, alanine, and oxalate in the ratio of 1:1:1) was introduced into the soil for 4, 10, and 20 days via an artificial root. We used a sequential extraction technique (i.e., resin-Pi, NaHCO3-P, NaOH-P, and HCl-P) to track the fate of applied P in bulk and rhizosphere soils. The root exudate effects on the rate of P cycling and microbial activity were investigated using phosphate oxygen isotope ratios in the resin-Pi pool. Microbial community structures was determined using phospholipid fatty acids (PLFA) profiles. After supplying root exudate for 4, 10, and 20 days, the results showed that bioavailable P (i.e., resin-Pi) concentration was always higher in the bulk soil compared to rhizosphere soil and originally bioavailable P transformed gradually into unavailable P (i.e., NaOH-P and HCl-P). After supplying exudate compound for 4 days, the applied PO4 was mostly in the resin-Pi pool and its isotopic composition was heavier than the equilibrium isotopic composition suggesting that this Pi pool was not completely cycled by the microorganisms. As we continue supplying exudate compounds, the concentration of resin-Pi gradually decreased and as microbial activities increased, its isotopic composition got closer to the equilibrium isotopic composition. Further the microbial community structure in the rhizosphere soil after supply of root exudate were distinctly different then the bulk soil. Using phosphate oxygen isotopes this study shows the influence of root exudates on the rate of P cycling in rhizosphere soils.
Data Driven Prediction of Seismic Ground Response under Low Level Excitation
Authors: Yoo Jaewon , Ahn Jaehun
Published: March 2020

It is an important task to model and predict seismic ground response; the results of ground response analysis are, in turn, used to assess liquefaction and integrity of undergound and upper structures. There has been numerious research and development on modelling of seismic ground response, but often there are quite large difference between prediction and measurement. In this study, it is attempted to train the input and output ground excitation data and make prediction based on it. To initiate this work, the deep learning network was trained for low level excitation data; the results showed reasonable match with actual measurements.

ACKNOWLEDGEMENT : The authors would like to thank the Ministry of Land, Infrastructure, and Transport of Korean government for the grant from Technology Advancement Research Program (grant no. 20CTAP-C152100-02) and Basic Science Research Program (grant no. 2017R1D1A3B03034563) through the National Research Foundation of Korea (NRF) funded by the Ministry of Education.
Phosphate dynamics in a sub-tropical lake ecosystem
Authors: Singh Priyanka , Haritash Anil Kumar , Joshi Himanshu
Published: March 2020

Lake Ecosystem is a key component of biosphere that supports aquatic life and provide sink to the untreated effluent (domestic, industrial, and agricultural). Due to rapid industrialisation and changing climate, 30-40% of the lakes in the world are now eutrophic. The basic cause of eutrophication is the addition of nutrients (nitrogen and phosphate) into the lake system. Phosphate has been observed to be the limiting nutrient in 80% of the lakes and reservoirs in the world. Unlike other elements, phosphate does not escape from the system but changes from one form to the other depending upon the prevailing physico-chemical conditions. Chemical parameters like pH and redox potential are the major governing factors for phosphate fluxes. Sediments in the benthic zone serves as a sink as well as the source of phosphate for the photic zone. In the present study, a relationship between the physico-chemical properties of water and the fractions of phosphate in the sediments were studied. The study was conducted during three different seasons i.e. post-monsoon, winter, and summer to observe the seasonal variation. The pH, DO, ORP, and available phosphate in the water varied from 8.5, 14.7 mg/l, 39 mV, and 5.8 mg/l, 8.4, 3.5 mg/l, -64 mV, and 8.7 mg/l, and 7.8, 7.3 mg/l, 119 mV, and 10.5 mg/l during post-monsoon, winter, and summer, respectively. Phosphate in sediments was fractionated using SMT protocol. It was categorised under inorganic and organic phosphate classes, and the inorganic phosphate was further categorised as Non apatite inorganic phosphate (NAIP: Fe/Al bound) and Apatite inorganic phosphate (AIP: Ca bound).  The inorganic phosphate in the sediments was observed to be more than organic phosphate during post monsoon and summer, and at the same time the available phosphate in the overlying water was found low in concentration. The growth of phytoplankton is constrained by decreasing bio available phosphate in water. Concentration of NAIP was observed to vary with redox potential and concentration of AIP with pH. The study justified the hypothesis of direct relationship of sediment chemistry with bio availability of phosphate in water. Winter was found to be the extreme weather for phosphate fluxes. The findings point towards need of proper management such as chemical precipitation, sediment dredging etc. during this extreme weather conditions.
A User Needs Assessment for the next Mass Change Satellite Mission
Authors: Srinivasan Margaret , Rodell Matthew , Reager John , Doorn Bradley , Rogers Laura
Published: March 2020

Planning is underway for development of the next NASA Mass Change satellite mission, as identified in the National Science Foundation’s 2017-2027 Decadal Survey for Earth Science and Applications from Space  (Decadal Survey). NASA has identified a Mass Change Designated Observable (MCDO) Study Team to evaluate satellite mission architectures that could optimally support a range of science and applications needs of user communities (both research and operational) of future mass change missions (i.e., successors to the GRACE and GRACE Follow On missions). The primary science objective of the MCDO, as identified in the Decadal Survey, is the continued measurement of changes in the Earth’s dynamic gravity field over time. The Decadal Survey also emphasizes applications of the mission data products as a major focus, in addition to science outcomes. 

Operational use and societal benefit derived from the GRACE and GRACE FO data and information products demonstrate the value of these missions. Applications include drought monitoring, quantification of groundwater depletion, flood prediction, and thermal expansion of the ocean, which contributes to sea level rise, to name a few. In order to effectively identify the observational product requirements of future gravity mission applications data users and to develop actionable objectives for mission design, a Mass Change Mission Applications survey was developed. Information on user needs, current uses, and capabilities derived from the survey have provided insights as to desired or required spatial scales, data latency, data formats, and technical capabilities of the users, as well as how to prioritize tradeoffs. The survey focused on evaluating the needs of a broad range of existing and potential user communities in order to incorporate these needs into mission design and architecture studies that are underway.

The survey comprises general questions about requirements for a given application, and data use and demographic information to help characterize aspects of the user community. Analyses of the survey results are now being used to inform potential mission architecture designs, evaluate tradeoffs, and ensure that the data products are optimized for a broad user community.
Tidal-librational dissipation within volcanic and cryovolcanic worlds
Authors: Trinh Antony , Matsuyama Isamu
Published: March 2020

Tidal dissipation is thought to power volcanism or cryovolcanism on a number of moons, most notably Io and Enceladus. The amount and distribution of tidal heating within the moon are however still misunderstood, and intricately related to surface observations like heat flow and distribution of volcanic activity. From an extensive benchmark between a set of numerical and semi-analytical models, we show that, in the presence of a subsurface (magma or water) ocean, librations (i.e. spin rate variations) along the orbit trigger additional deformation mechanisms, enhancing the amount of dissipation compared to traditional tidal dissipation (by at least 25% for Enceladus), and affecting the distribution of dissipation within the moon. We illustrate these mechanisms with numerous animations, and identify librational loading as the most relevant process.
The Impact of Kuroshio Extension Fronts Variation on the Pacific Storm Tracks and the relationship with Temperature over North America
Authors: Xiao Ziniu
Published: March 2020

The intensity index of Kuroshio Extension and northern front zones (KEF) is defined as the area average of SST meridional gradient by using Hadley Center’s surface sea temperature dataset (1949-2014), and the Kuroshio Extension frontal intensity index (KEFI) has seasonal to interdecadal variations. In winter, the KEFI has significant positive correlation with transient variances in the North Pacific storm tracks area, and the positive relationship appears when KEFI lead storm tracks one month which indicates the intensity of KEF could influence storm tracks in winter. To investigate the possible mechanism, we found: when the winter SST front is stronger, the more significant difference between ocean-air heat flux in both sides of KEF could strengthen the near-surface temperature gradient, which maintains the near-surface baroclincity and benefits the transient heat transport, promote the develop of transient eddies at last. Additional, the large-scale circulation also be response to KEF in winter: when the KEF is stronger, the Aleutian is deepen, the subtropical high is strengthen, the 500 hPa potential high is increased (decreased) in south (north), the subtropical jet is weaker and wider. It is found that the oceanic fronts promote storm tracks by transporting heat upward and maintaining the air temperature gradient in winter. In further, the significant correlation was found between the Kuroshio Extension Oceanic Front intensity and the temperature over North America in autumn and winter.