bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influences of Climate Forcers and Agricultural Activities on the South Asian Summer Monsoon
Authors: Dhungel Shradda , Tsigaridis Kostas , Bauer Susanne
Published: March 2020

South Asia is one of the most heavily populated regions in the world with about 1.7 billion inhabitants. The diversity of human activities in the region make delineating the sources and magnitude of regional emissions complex. The major combustion sources in South Asia – predominantly anthropogenic – include wildfires and the burning of agricultural residues, garbage, biofuels, and fossil fuels. But regional aerosol loading is also heavily influenced by natural aerosols, primarily dust transported from as far as the Arabian Peninsula. Past studies have examined how irrigation expansion along with greenhouse gas (GHG) forcing have altered the surface energy budget, thereby affecting the transport of water vapor and altering South Asian Summer Monsoon (SASM) rainfall variability. However, there are still limited modelling studies that consider anthropogenic effects from anthropogenic aerosol loading in combination with irrigation and GHGs and how these factors collectively induce variability in the SASM. Using the NASA GISS-E2.1 model, this study elucidates the role of intensive agricultural activities on SASM, both at the onset of the Green Revolution (i.e., 1960s) and at present, isolating the individual roles of irrigation, anthropogenic aerosols, and GHGs. Specifically, we examine the impacts on SASM by using sensitivity runs to quantify how anthropogenic emissions from agriculture, urbanization as well as long- and short-term forcers have affected SASM from 1960-2014 using prescribed- and coupled-ocean runs. Understanding the roles of each of these influences on SASM can help to develop more effective climate interventions in the region and predict how SASM will influence and interact with the changing regional and global climate.
Fire in the environment: effects on soil functions and ecosystem services in a changing world
Authors: Muñoz-Rojas Miriam , Pereira Paulo
Published: March 2020

Fire is an essential element of the environment and a vital force for shaping landscapes all around the world. It has a critical role as driver of natural ecosystem processes and many plant communities are fire dependent aros the globe. However, although fire is a natural and regular component of some biomes in the Earth’s systems, it can become a destructive force when natural ecosystems are disturbed, fire is introduced at a rate not previously experienced, and recovery to a pre-fire state is not possible. Thus, assesing the potentially harmful environmental impacts of fire and building the underlying knowledge required to successfully manage fire makes are crucial in order to understand the role of fire in all its different dimensions. Over the past year, fires in California in the United States and in the Amazon rainforest in Brazil have grabbed the world’s attention. The increased rates of fire events in some of these areas, mostly attributed to land degradation processes, have led to international concern. More recently, several bushfires all around Australia have had dramatic impacts in the environment with 10 million hectares burned so far, including large portions of the natural environment. These unprecedented fires are predicted to affect to a large extent the soil characteristics, processes and function in several ecosystems. In this presentation, we highlight some of the most recent research published during the last year on the effects of fire on soil functions and the provision of soil ecosystem services. We also showcase some of the possible approaches to protect and conserve soil ecosystems affected by extreme fires and propose available strategies for post-fire management.
Evaluation of precipitation and actual evaporation products over the Nile Basin
Authors: Baez-Villanueva Oscar M. , McNamara Ian , Zambrano-Bigiarini Mauricio , Ribbe Lars
Published: March 2020

An improved representation of the spatio-temporal patterns of climatological variables is crucial for ecological, agricultural, and hydrological applications and can improve the decision-making process. Traditionally, precipitation (P) and actual evaporation (ETa) are estimated using ground-based measurements from meteorological stations. However, the estimation of spatial patterns derived solely from point-based measurements is subject to large uncertainties, particularly in data-scarce regions as the Nile Basin, which has an area of about 3 million km2. This study evaluates six state-of-the-art P products (CHIRPSv2, CMORPHv1, CRU TS4.02, MSWEPv2.2, PERSIANN-CDR and GPCCv2018) and five ETa products (SSEBop, MOD16-ET, WaPOR, GLEAM and GLDAS) over the Nile Basin to identify the best-performing products. The P products were evaluated at monthly and annual temporal scales (from 1983 onwards) through a point-to-pixel approach using the modified Kling-Gupta Efficiency and its components (linear correlation, bias, and variability ratio) as continuous performance indices. The ETa products were evaluated through the water balance approach (due to the lack of ground-based ETa measurements) for 2009-2018 at the multiannual scale. Because streamflow data were not available for this period, an empirical model based on the Random Forest machine learning technique was used to estimate streamflow at 21 catchments at the monthly scale. For this purpose, we used streamflow data from 1983 to 2005 as the dependent variable, while CHIRPSv2 precipitation and ERA5 potential evaporation and temperature data were used as predictors. For the catchments where the model performed well over the validation period, streamflow estimates were generated and used for the water balance analysis. Our results show that CHIRPSv2 was the best performing P product at monthly and annual scale when compared with ground-based measurements, while WaPOR was the best-performing ETa product in the water balance evaluation. This study demonstrates how remote sensing data can be evaluated over extremely data-scarce scenarios to estimate the magnitude of key meteorological variables, yet also highlights the importance of improving data availability so that the characterisation of these variables can be further evaluated and improved.
Observational analysis of Mediterranean decadal hydroclimate variability: role of Atlantic-Mediterranean sea surface temperatures
Authors: Suarez-Moreno Roberto , Seager Richard , Kushnir Yochanan
Published: March 2020

The Mediterranean region is a semi-arid climate zone, subject to droughts, where water resources are scarce and observational data and climate models suggest a tendency towards greater aridification. Moreover, the Mediterranean region is an area of social and political instability and, in the Middle East, open warfare, which might be further stressed by climate change. The North Atlantic Oscillation (NAO) is the dominant mode of winter climate variability in the North Atlantic sector, playing the leading role in driving Mediterranean hydroclimate variability from seasonal to multidecadal timescales, whereas the influence of sea surface temperatures (SSTs) remains unclear. Nevertheless, the mechanism underlying the NAO is still under debate, and the possibility for coupled ocean-atmosphere decadal interactions, for which several mechanisms have been proposed, would support the role of SST. Based on observations and reanalysis, we conduct a statistical-observational analysis to explore the decadal drivers of Mediterranean hydroclimate variability for the winter half-year (October-to-March) wet season. Our results put forward the uneven intraseasonal influence of the decadal NAO, being the leading driver during the winter peak season (December-to-March), while decadal Atlantic-Mediterranean SST variability exhibit a consistent link for the first months of the wet season (October-to-January). These results emphasize the need to further explore the ocean-atmosphere feedback mechanisms and their possible modulations under climate change. Understanding these mechanisms is essential to improve predictability of hydroclimate in the Mediterranean region, leading to adaptation strategies that mitigate the effect of climate change on the vulnerable population.
A Study on the Estimation of the Occurrence Frequency of Mega-drought by the Characteristics of Drought Damage
Authors: Youngseok Song , Jinbok Kim , Jongun Park , Moojong Park
Published: March 2020

Unlike natural disasters such as typhoons, torrential rains and floods, drought is a disaster caused by long-term effects as well as short-term effects. The effect of drought is caused by damage from a short period of weeks to a long period of years, which causes extensive and enormous damage to agriculture, life, society and economy. In addition, the recent climate change has affected the frequency and scale of rainfall in the global temperature, so it is necessary to prepare measures against it.

The past studies on drought have been conducted using drought indexes such as agricultural, meteorological, and hydrological methods to evaluate drought. The representative drought indexes for each drought are Palmer Drought Severity Index (PDSI), Standardized Precipitation Index (SPI), Agricultural drought is Crop Moisture Index (CMI), Crop Specific Drought Index (CSDI), Hydrological drought is Surface Drought Water Supply Index (SWSI), Reclamation Drought Index (RDI) and so on are used. However, these drought indices are only used as a method of predicting the depth of drought, and do not give the actual number of drought occurrences.

In this study, we want to determine the frequency of Mega-drought occurrences in consideration of the drought damage characteristics that occurred worldwide from 1900 to 2018. The drought damages in the world were used by EM-DAT (the Emergency Events Database) which manages disaster data in CRED (Centre for Research on the Epidemiology of Disasters). Drought damages occurred in the world from 1900 to 2018 occurred more than once/years in 146 countries. The duration of drought persistence occurred in the country continuously for at least one to 17 years. The purpose of this study is to propose the criteria for mega drought by using the past victim data in connection with the incidence frequency.

Acknowledges : This research was supported by a grant(2019-MOIS31-010) from Fundamental Technology Development Program for Extreme Disaster Response funded by Korean Ministry of Interior and Safety(MOIS).

 
A Study on the Establishment of Criteria for Reduction measures of Mega Drought in Korea
Authors: MooJong Park , Youngseok Song , Heesup Lee , Juhyeok Park
Published: March 2020

Recently, climate change due to global warming has been frequented by large-scale weather disasters that have not been experienced in the past. Among various weather disasters, drought is one of the representative weather disasters in Korea recently along with heavy rains. In the case of drought, it occurs in a wide range in the short term and long term, and it is difficult to identify specific occurrence times, places, and causes, and damage and influence are enormous.

In the past, the Republic of Korea has been prepared with non-structural measures such as securing irrigation water for drought restoration, developing emergency management, and developing a drought information system based on drought index. The reduction measures for drought degradation were mainly used by Palmer Draught Severity Index (PDSI), Standardized Precision Index (SPI), Crop Moisture Index (CMI), Crop Specific Drug Index (CMI), and Profication (DICS Index), and Survey.

In this study, we intend to establish standards for reducing drought damage by investigating and analyzing drought damage characteristics in Korea. In the past, drought damage in Korea occurred in agriculture, living and industry, and the ministry manages and stores the data on drought damage. The drought damage in South Korea from 1965 to 2018 occurred a total of 204 times, mostly in South Gyeongsang and South Jeolla provinces, rather than in special cities and metropolitan cities. The purpose of this study is to analyze the characteristics of drought damage in Korea and establish the measures to reduce mega drought.

Acknowledges : This research was supported by a grant(2019-MOIS31-010) from Fundamental Technology Development Program for Extreme Disaster Response funded by Korean Ministry of Interior and Safety(MOIS).
Constraints on the rheology of the mid- to lower continental crust from geodetic studies of the earthquake deformation cycle
Authors: Wright Tim , Ingleby Tom , Hussain Ekbal
Published: March 2020

In this presentation I will review geodetic constraints on the rheology of the mid- to lower continental crust from observations and models of all phases of the earthquake deformation cycle. I will focus on observations of slow interseismic strain accumulation and rapid postseismic strain transients, both of which result primarily from deformation in the mid- to lower crust. I will argue that, with a few exceptions, interseismic strain is focused in zones around faults with widths that are compatible with strain at depth being focused on a fault or distributed in a shear zone up to ~3 x the seismogenic layer thickness. I will show that for the North Anatolian Fault, the strain accumulation rate appears to be approximately constant for the entire earthquake cycle, once the postseismic transient has decayed. This is consistent with observations at other fault where geodetic measurements were made prior to major earthquakes; the broad agreement between geological and geodetic estimates of slip rate is also consistent with interseismic strain accumulation rates being relatively time invariant. Time-invariant interseismic strain accumulation rates require a relatively strong mid- to lower crust, where relaxation times are equal to or greater than the average earthquake revisit time. Postseismic deformation transients are commonly observed following most earthquakes, but they are interpreted using a variety of very different deformation mechanisms. By compiling all observations of postseismic deformation we show that the largest transient postseismic velocities decay following a simple t-1 power-law, analogous to Omori’s law for aftershock decay. This is consistent with frictional afterslip and/or power-law creep in a narrow shear zone. This model of a weak shear zone embedded within a stronger substrate can explain most observations of the earthquake deformation cycle. Exceptions to this simple model might occur in locations where the lower crust is weaker, perhaps due to the presence of partial melt. Geological constraints on rheology are critical for making further progress in understanding the earthquake deformation cycle – geological models for the mid- to lower crust can be tested by comparing geodetic observations with geologically-realistic earthquake cycle models.
Young water dominance in the humid tropics in Costa Rica
Authors: Correa Alicia , Birkel Christian , Gutierrez Jason , Dehaspe Joni , Duran-Quesada Ana María , Soulsby Chris , Sánchez-Murillo Ricardo
Published: March 2020

The headwater catchments in the humid tropical forests are of major hydrological importance for regional and global climate systems and provide essential ecosystem services such as water supply for other ecosystems and industrial use in the lowlands. Anthropogenic pressure together with global environmental changes critically alter the hydrological functioning of these catchments. However, limited knowledge jeopardizes a proper water resources management of such water towers.

To contribute to filling this gap, we conducted a field monitoring of hydro-climatic and isotopic data (01.2013 – 07.2018) in a pristine tropical rainforest catchment (3.2 km2) in Costa Rica and used this data to test hypotheses about water age dynamics. The Spatially-Distributed Tracer-Aided Rainfall-Runoff model for the tropics (STARRtropics) was applied in high temporal (hourly) and spatial (10m) resolution. The best-obtained model simulations reflected a highly variable range and distribution of water ages. Nevertheless, superficial flow paths with young water contributions (40 months at most) dominate the streamflow generation entirely. The maximum water age was independently evaluated calculating the tritium-derived baseflow mean transit time. The highest simulated ages of transpiration flux varied between 12 days and 5.5 months depending on the soil depths where the water was uptake. Soil water age peaked at 5.4 months and groundwater at 40 months. The oldest stream water age, integrating all catchment processes, reached 24 months. Overall, the water age increased during dry conditions. The frequency of water ages reflected high occurrences of young water for transpiration flux and streamflow in their respective ranges. Maximum occurrences were reported for transpiration with 10 hours and streamflow with 2.8 months. The soil water age presented a bimodal distribution with peaks of 2.8 and 4.4 months and groundwater age occurrences peaked at 32 and 37 months. Spatially, high age dynamics of transpiration flux were associated with a higher leaf area index on the northern hillside in relation to the southern hillside. The oldest soil water was related to more developed soils and the groundwater age increased towards the bottom of the catchment. In the context of the tropics, our study is one of the first that quantitatively evaluated water age dynamics and distributions, and globally using such a high spatial and temporal resolution with a non-stationary perspective. These findings will support decision-makers to manage the water resources and ecosystem in the humid tropics and reduce the research gap regarding hydrological processes of tropical headwater towers under environmental changes.
Hydrologic assessment of a small maritime hydrometric monitoring network using a combined inductive-deductive process-informed catchment classification system
Authors: Johnston Lindsay , Dunnington Dewey , Greenwood Mark , Kurylyk Barret , Jamieson Rob
Published: March 2020

The National Hydrometric Program, operated by the Water Survey of Canada, is the primary source of surface water quantity data in Canada. The network is cost-shared between the federal and provincial governments, and decisions relating to station placement are made according to both federal and provincial interests. Nova Scotia is a small maritime province in Atlantic Canada that is roughly one third the size of England and Wales and has a diverse climate and geology. The Nova Scotia hydrometric monitoring network currently consists of just 31 stations. The overall objective of this study was to determine how well the current network captures the level of hydrologic variability expected in the province using a regional catchment classification scheme. To accomplish this, we developed a combined inductive-deductive catchment classification system and applied it to the province’s active monitoring network and ungauged major watersheds. Initially, hydrologic signatures were used to quantify the catchment function of 47 long-term gauged catchments and to cluster similarly behaving catchments. We identified five generalized flow classes and then attempted to replicate this classification using a deductive-based decision tree framework with physiographic and meteorological explanatory variables. The validated decision tree was used to classify the active hydrometric network and 250+ major watersheds in the province. The network was assessed to determine how well it covered the expected hydrologic variability in the major watersheds across the province. The decision tree proved to be a useful tool for understanding the current network’s coverage and could also be easily applied by practitioners to identify appropriate donor catchments for ungauged watersheds.
The Progress of KMA’s Impact-based Forecasting
Authors: Han Hyojin , Park YoungYoung , Kim Ji-Hyeon , Ahn Yongjun , Lee KyongJun , Song Ji Ae , Kim Yeongseon , Kim Wonho
Published: March 2020

The Korea Meteorological Administration (KMA) set a main policy goal as “Impact-based forecasting (IBF) for mitigation of meteorological disaster risks” in 2016. As a first step toward the goal, each regional office of the KMA operated a prototype of impact-based forecast service tailored to major severe weather conditions in each region from 2016 to 2018. As a result, the prototype service was found to contribute to reducing meteorological disasters in those regions. In order to determine quantitative impacts caused by meteorological disasters, a multi-ministerial R&D project was began in 2018 which is aiming to develop the Hazard Impact Models (HIM) for heavy rainfall and heatwave/coldwave. The project will be completed by the end of 2020, and the developed HIM will be operated for the KMA operational IBF. 
The KMA officially launched heatwave IBF service from June to September 2019 in order to support effective reduction of heatwave impacts. The KMA provided risk levels in different colors (attention-green, caution-yellow, warning-orange, danger-red), impact information and response tips for seven sectors—health, industry, livestock, aquaculture, agriculture, transportation and electric power—considering the regional characteristics. This information was disseminated to the public on the KMA's website. It was also provided to disaster response related agencies through the Meteorological Information Portal Service System for Disaster Prevention, as well as to local governments’ disaster response managers and officials managing the socially vulnerable people through mobile text messages. According to user satisfaction survey, a great number of users showed positive responses to the KMA heatwave IBF. Based on the success of heatwave IBF, coldwave IBF trial service was offered from December 2019 to March 2020. In addition, KMA plans to expand IBF to other high-impact weathers such as typhoon, heavy snow, heavy rainfall, and so on.
Calibration of a semi-distributed hydrological model adding constrains from remotely sensed snow cover and soil moisture products
Authors: Tong Rui , Parajka Juraj , Komma Jürgen , Blöschl Günter
Published: March 2020

Remote sensing products have been widely applied in hydrological modeling for more realistic representations of hydrological processes. In this study, in addition to gauged discharge, the combined MODIS snow cover maps and ERS scatterometer based soil moisture products were added to constrain a semi-distributed conceptual hydrological model. The latest version of MODIS snow cover images provides a daily Normalized Difference Snow Index (NDSI) in a 500-meter resolution. We derived the snow cover maps by using a new NDSI thresholding method from the MODIS Aqua (MYD10A1) and Terra (MOD10A1) daily snow cover products. Furthermore, the newest ERS soil moisture product also provided a finer spatial resolution of 500-meter over Austria. The semi-distributed TUW-model was tested in 213 catchments using both single and multiple object calibration methods. We found that the semi-distributed TUW-model performed well in discharge modeling. Moreover, applying the MODIS snow cover maps improved the accuracy in the snow-melt season, while the soil moisture product helped the discharge simulation in the no-snow period.
Evaluation of globally gridded SST products from NOAA, CMC and UKMeto using AIRS and CrIS SST measurements.
Authors: Aumann Hartmut , Manning Evan , Wilson Chris , Vasquez Jorge
Published: March 2020

The Sea Surface Temperature (SST) is a key component of climate research and daily globally gridded SST products are a key input to this effort.  Here we evaluate the NOAA RTGSST, which goes back to 1996, the Canada Meteorological Center (CMC) SST, available since 2002, and the OSTIA SST by the UK MetOffice, available since 2012. The calibration of the three products is tied to the moored and floating buoys along the equator, but there are differences in the way all grid points are optimally filled. The 2016 annual mean between 30S and 30N, 299.7K, differed by only 8 mK. However zonal mean differences between the three products north of 30N and south of 30S latitude are  of the order of 150 mK, and of opposite signs. Even more puzzling is that during 2016 the CMC was on average 150 mK colder than the OSTIA at 280K, while being warmer by 150mK at 290K. Differences of this magnitude are of concern when measure warming of the oceans at the rate of 15 mK/year. We use the daily mean and standard deviation and trends of the difference between the SST measured with AIRS (Atmospheric Infrared Sounder) since 2002 and CrIS (Crosstrack Interferometer Sounder) since 2012 to evaluate the three products.         
Ultra-high-resolution future coupled model projections of atmospheric rivers
Authors: Nellikkattil Arjun , Guan Bin , Lee June-Yi , Timmermann Axel , Lee Sun-Seon , Waliser Duane , Chu Jung-Eun
Published: March 2020

Atmospheric rivers (ARs) are narrow, elongated structures, transporting large amounts of water vapor from the tropics towards polar regions. These synoptic scale features play an important role in the global hydrological cycle and for extreme precipitation events. To study how ARs will change in response to greenhouse warming we use a series of century-long fully coupled ultra-high-resolution simulations conducted with CESM 1.2.2 with an approximate horizontal resolution of ~25 km in the atmosphere and 10 km in the ocean. The simulations were carried out for present-day, 2xCO2 and 4xCO2 conditions. In this high atmospheric resolution, we obtain a much more realistic representation of complex orographic features (such as the Rocky Mountains), which can greatly influence the extreme precipitation often associated with ARs. Results from the present-day simulation are compared with ERA-Interim data to validate the model's fidelity in representing ARs. Our analysis focuses on future greenhouse-warming induced changes in AR frequency, geometry, landfalling latitude and strength. We find a global increase in the frequency of ARs amounting to ~0.5% for 2xCO2 and 0.9% for 4xCO2 respectively. In subtropical areas, such as the southwestern part of the United States AR frequencies increase by up to 7%. The presentation will further document the underlying processes for this increase.
Changes in root zone storage capacity and their effects on river discharge and gross primary production
Authors: Nóbrega Rodolfo , Sandoval David , Prentice Colin
Published: March 2020

Root zone storage capacity (Rz) is a parameter widely used in terrestrial ecosystem models that estimate the amount of soil moisture available for transpiration. However, Rz is subject to large uncertainty, due to the lack of data on the distribution of soil properties and the depth of plant roots that actively take up water. Our study makes use of a mass-balance approach to investigate Rz in different ecosystems, and changes in water fluxes caused by land-cover change. The method needs no land-cover or soil information, and uses precipitation (P) and evapotranspiration (ET) time series to estimate the seasonal water deficit. To account for some of the uncertainty in ET, we use different methods for ET estimation, including methods based on satellite estimates, and modelling approaches that back-calculate ET from other ecosystem fluxes. We show that reduced ET due to land-cover change reduces Rz, which in turn increases baseflow in regions with a strong rainfall seasonality. This finding allows us to analyse the trade-off between gross primary production and hydrological fluxes at river basin scales. We also consider some ideas on how to use mass-balance Rz in water-stress functions as incorporated in existing terrestrial ecosystem models.
Updating the Augmented Reality Sandbox for Geophysics, Structural Geology and Stratigraphy
Authors: Klump Jens , Muhumuza Kenneth , Engelke Ulrich , Francis Neil
Published: March 2020

One of the challenges for students of geosciences is learning to read geological maps, interpret structural geology, and understand the link between geology and geophysical properties. Augmented Reality (AR) sandboxes are interactive visualization tools that are becoming increasingly popular to demonstrate various earth processes. 

An AR sandbox consists of a box filled with white sand and uses a Kinect 3D camera to continuously scan the topography of the sand surface. The topographic view of the structures sculpted by the user is then blended with digital information and a computed image is projected back onto the sand surface. Due to their intuitive operation, AR Sandboxes serve as a powerful science outreach and communication tool by making abstract concepts easy to see through the leveraging of playful learning and visualization, offering huge potential for teaching geological and geophysical principles.

Several versions of AR Sandboxes have been developed for a whole range of scenarios, spanning a wide variety of Earth Science topics and learning environments. The most common scenarios are from physical geography, hydrology and ecology. Their underlying data models stay at or close to the surface, making it hard to incorporate geological models. 

Recently, an Open-AR-Sandbox software was published by researchers at the Institute for Computational Geoscience and Reservoir Engineering (CGRE), RWTH Aachen University, Germany. With this AR Sandbox, geological models can be projected onto real sand and the relations of subsurface structures, topography and outcrop can be explored in an AR environment. 

We tested the Open-AR-Sandbox software after successfully installing and running a conventional AR sandbox software. The combination of the Sandbox and GemPy geomodelling tool offers unique 3D interactive modelling solutions to explore geoscientific data and processes, with linkages to other software tools. We can use the AR sandbox to project a variety of geophysical measurement data onto the sand surface, offering an interactive experience that integrates geological and geophysical data. The Open-AR-Sandbox is, therefore, an innovative tool in geoscience education for the public as well as the classroom because of its benefits for teaching geological mapping, structural geology and geophysics.
Simulated GPS radio occultation signals from sporadic-E layers
Authors: Emmons Daniel
Published: March 2020

A multiple phase screen model is used to simulate GPS radio occultation signals through varying sporadic-E layers.  The length, vertical extent, and plasma frequency of the sporadic-E layers are varied to analyze the effect on the signal received by a low earth orbiting satellite.  A nonlinear relationship between the maximum variance in the signal amplitude and the plasma frequency is observed.  For certain frequency ranges, the predictions match previous studies that have used the S4 scintillation index to predict fbEs values. Additionally, the spectra of the signals are analyzed as a function of the different parameters providing an alternative approach for extracting sporadic-E parameters from GPS radio occultation measurements. 
Asynchrony of winter soil freeze-thaw phenology induced by warming reduces ecosystem respiration of alpine meadow during the freeze-thaw period
Authors: wang shiping , wang qi , lv wangwang , zhou yang , jiang lili
Published: March 2020

Changes in winter soil freeze-thaw (F-T) phenology not only affect nature, but also affect social-economy in permafrost regions. However, a lack of understanding of its response to global warming is a critical gap in knowledge to preclude adaptation to climate change. Here we explored effects of warming gradient (0, 1, 2 and 4oC) combined with precipitation addition on it by which further on CO2 emission on the Tibetan Plateau. We find that only warming delays start and end dates of soil F-T cycle during autumn-winter season, but advances them during winter-spring season, thus shortens the durations of completely freezing (14.9 days oC-1) and total duration of soil F-T period from autumn to spring (11.7 days oC-1). Thus, asynchronic shifts of the soil F-T cycle induced by warming significantly decreased total CO2 emission by 31-47% relative to T0 treatment during the whole F-T period from autumn to spring.
Partitioning the denudation flux between silicate and carbonate physical erosion and chemical weathering in the Northern Apennines
Authors: Erlanger Erica , Caves Rugenstein Jeremy , Bufe Aaron , Picotti Vincenzo , Willett Sean
Published: March 2020

The Northern Apennines of Italy are a young orogen comprised of mixed siliciclastic and carbonate lithologies. Young orogens are typically characterized by marine sedimentary sequences that contain important volumes of carbonate, which can dominate chemical weathering, as carbonate weathers a factor of 3 times faster than silicates. However, most models that address the interplay between erosion and weathering have focused on silicate lithologies.  Carbonate weathering is typically limited by the availability of acid rather than dissolution kinetics, and more tightly linked to soil and sub-surface CO2 concentrations than silicate weathering. Therefore, it remains unclear if the same processes that control the partitioning of denudation between erosion and weathering in actively uplifting, silicate-rich lithologies are also active in orogens comprised of mixed carbonate-silicate lithologies. The partitioning of denudation between physical erosion and chemical weathering in mixed silicate-carbonate landscapes remains a fundamental knowledge gap that has implications for landscape development and the carbon cycle. Here we address two key questions: (1) how is the total denudation separated into carbonate and silicate fluxes, and (2) how is carbonate denudation partitioned into erosion and weathering in an active orogenic setting? We partition denudation fluxes from 10Be concentrations into carbonate and silicate chemical weathering and physical erosion fluxes, using major dissolved ions from water chemistry, the percent of carbonate sand from each catchment, and annual discharge measurements. Denudation fluxes in the Northern Apennines are dominated by physical erosion of both silicate and carbonate lithologies. Chemical weathering fluxes are 1-2 orders of magnitude lower than physical erosion fluxes and are dominated by carbonate dissolution. Despite a number of studies that have shown a strong positive correlation between denudation and chemical weathering fluxes, we find only a weakly positive correlation. Relative to a global dataset from silicate-rich orogenic settings, the Northern Apennines have similar denudation fluxes as the eastern side of the New Zealand Southern Alps. However, rivers from the Northern Apennines generally have higher total weathering fluxes relative to the Southern Alps, consistent with the exposure of a large volume of carbonate lithologies in the Northern Apennines.
Asbestiform anthophyllite, tremolite, and related fibrous amphibole chemistry, both as primary and secondary mineralization in metamorphic facies in asbestos occurrences in North American deposit comparisons
Authors: Fitzgerald Sean
Published: March 2020

As we continue to investigate the asbestos-forming minerals and their associated geology as they occur in North America, we have found that subtle variations can make the standardization of what is and what is not asbestos more difficult. On the other hand, some geochemical trends recently observed have given us significant insight into what we can expect in the ground, which we hope will lend much-needed information to medical investigators to better understand the relationship of mineral morphologic and chemical differences and the ramifications to human health for those potentially exposed. In efforts to understand why certain minerals form in the asbestiform habit, mineralogists still cannot fully explain the cause-and-effect of this phenomenon. Although we know that there are chemical variances and pressure or temperature regimes that are conducive to the formation of asbestos, a complete and absolute picture of how and why amphibole forms fibers, or serpentine forms chrysotile scrolls remains elusive. Research indicates however that there are two primary ways that sheet silicates compensate for the fundamental misfit between their tetrahedral silica layers (T) and their octahedrally-coordinated cation layers (O) that is by either tetrahedral rotation /stretching or by bending or modulation of the layers in concert. Rotation or stretching occurs in both the 1:1 layer silicates (T-O) such as serpentines, and the 2:1 phyllosilicates (T-O-T) such as vermiculite or talc. The other primary means of misfit compensation is structural bending, with the obvious examples of antigorite or chrysotile. Although it was originally hypothesized as early as the 1950s that this curving or bending of the sheet structure was entirely due to the T-O misfit, more recent research points to the importance and variances of hydroxyl bonding in the chrysotile structure. A secondary mode of compensation for the fundamental misfit is by the addition or subtraction of silica tetrahedra or octahedral cations in modulated fashion, which affects the overall chemistry of the mineral as a whole. In polysomatic hydrous biopyriboles we see the importance of hydration alteration reactions in the transformation of chain zippers. Thusly, a wide variety of intergrowth microstructures appear in Mg-rich 1:1 modulated layer silicates, analogous to the hydrous biopyriboles as is common intimate intermixing in a polysomatic series. It is therefore common that the means by which all of our regulated asbestos minerals form is through the combined action of T-O misfit compensation and the action of water in the crystallizing or re-crystallizing process. 
Impacts of Land Use Change on Food Security in Nigeria: An integration of stakeholder participation in bioeconomic modelling
Authors: Ivo Kashimana Amanda
Published: March 2020

Two hundred million persons at an annual population growth rate of 2.5% in addition to uncertainty in climate and societal changes challenges development goals particularly food security in Nigeria. Food security challenges primarily originate from conflicts in agricultural and forestry land systems causing changes in the systems. Agricultural and forestry land systems constitute 77.7% and 7.7% of land area in Nigeria. However, pressured by an increasing population and a changing climate, society and even seemingly divergent policy objectives, these systems have failed to ensure food security. The challenge for Nigeria is to simultaneously maintain a 5% annual increment in food production and conserve 10% of its land area as forest. With agriculture already occupying 77.7% of the total land area, what will a 5% annual increment in food production and a 10% conservation of land area mean for both agriculture and forestry systems? Would these targets require an expansion or intensification or an integration of both systems? This paper provides insights into opportunities and trade-off for optimal land use systems in Nigeria by answering questions such as how can its land use be optimized for biodiversity conservation and agricultural production targets? Amidst the aforementioned targets what plausible governance, management technologies and policy adjustments can aid food security in Nigeria and at what cost?
Vertical distribution of ozone in summer and autumn in Guangdong Province, Southern China
Authors: Wang Xinqi , Zhang Tianshu , Xiang Yan , Lv Lihui
Published: March 2020

A differential absorption lidar was used to study the vertical structure of ozone in Jiangmen city and Yangjiang city, Guangdong Province, Southern China in summer and autumn of 2019, and analyze the two typical pollution characteristics and spatial-temporal distribution characteristics of atmospheric ozone local pollution and regional transport. The results show that the vertical concentration of ozone in Jiangmen city in the summer and autumn seasons is characterized by a single peak of ozone in the afternoon. It is mainly distributed below 600 m in summer and mainly distributed within 1.0 km in autumn. There is ozone residual in Yangjiang city in summer at night. In summer, the differences between the average ozone values in Jiangmen city and Yangjiang city are small, being 92.22 μg/m3 and 82 μg/m3, respectively. In autumn, the average ozone concentration in Jiangmen city is 1.58 times the ozone concentration in Yangjiang city, which is 122.27 μg/m3 and 77.36 μg/m3. In the process of local pollution, high-concentration ozone is mainly concentrated near the ground, and the ozone concentration of 1.5-2km tends to be uniformly distributed. In regional transport, the transport heights of the two stations are mainly in two height intervals, ranging from 0.7 to 1.1 km and above 1.1 km. And use TrajStat to perform trajectory clustering analysis on the main airflows that affect Jiangmen city and Yangjiang city in summer and autumn, the dominant directions of ozone transport at the two cities in summer and autumn are analyzed. In addition, we studied two typical pollution processes, on August 24, the lidar of both cities detected the presence of ozone input and sedimentation at a height of about 1.5 km, and found that the ozone transport came from the northeast through the backward trajectory. During September 28-30, the two cities were locally polluted by ozone and there were obvious ozone residues at night.

Keywords: Differential absorption lidar；Ozone；Local pollution；Regional transport

 
Near-field directionality of earthquake strong ground motions measured by displaced geological objects
Authors: King Tamarah , Quigley Mark , Clark Dan
Published: March 2020

Coseismically displaced rock fragments (chips) in the near-field (less than 5 km) of the 2016 moment magnitude (MW) 6.1 Petermann earthquake (Australia) preserve directionality of strong ground motions. Displacement data from 1437 chips collected over an area of 100 km2 along and across the Petermann surface rupture is interpreted to record combinations of co-seismic directed permanent ground displacements associated with elastic rebound (fling) and transient  ground shaking, with intensities of motion increasing with proximity to the surface rupture. The observations provide a proxy test for available models for directionality of near-field reverse fault strong ground motions in the absence of instrumental data. This study provides a dense proxy record of strong ground motions at less than 5 km distance from a surface rupturing reverse earthquake, and may help test models of near-field dynamic and static pulse-like strong ground motion for dip-slip earthquakes.
Willow recruitment and channel patterns in beaver dominated stream systems
Authors: Levine Rebekah , Tarmichael Megan , Meyer Grant
Published: March 2020

Beaver activity can segment a stream corridor through dam building which locally affects channel slope and sediment transport.  We have found, however, that long-term beaver presence within a river corridor has impacts beyond dam sites that affect system-wide stream morphodynamics and riparian willow recruitment. Along study streams (basin areas 20 – 125 km2) in southwestern Montana, USA, beaver-chewed willow stems (beaver cuttings) from dam construction, food caches and herbivory float downstream and commonly accumulate within 1 km of dam sites. At the 90 randomly selected sites surveyed, beaver cuttings accumulated on 81% of point bar sites and 51% of all surveyed sites. The accumulated beaver cuttings can sprout, adding roughness, thus enhancing sediment accumulation on point bars and at abandoned dam sites. Sprouting stems were present at 25% of all sites, indicating that beaver cuttings commonly provide a secondary pathway for willow recruitment and influence sediment dynamics.

As beaver cuttings and sediment accumulate on point bars, the channel migrates laterally, burying the cuttings. High resolution aerial imagery has been used to calculate migration rates for twenty-six 200 m reaches in the study streams. Migration rates range from 0.07 – 2.91 m/yr (mean 0.43 m/yr) over a 14 year period from 1995-2009. Thirty-four radiocarbon (14C) ages found in fluvial terraces 1.2 – 3 m above the bankfull channel, show that beaver cuttings range in age from ~6030 – 380 cal yr BP, demonstrating that deposition and burial of beaver cuttings on point bars has been a common process over millennia. The long-term preservation of beaver-chewed wood in point-bar sequences also attests to the importance of beaver activity for enhancing carbon storage in beaver-occupied stream systems.

The mosaic of sites created by beaver includes intact dams, recently breached or abandoned dams, and long-abandoned dams, interspersed with reaches unsuitable for beaver. The beaver produced habitat heterogeneity interacts with sediment and beaver cutting transport to enhance riparian plant colonization and meander development.
Combining Differential Absorption Radar and Microwave Radiometer for Water Vapor Profiling in the Cloudy Trade-Wind Environment
Authors: Schnitt Sabrina , Löhnert Ulrich , Preusker Rene
Published: March 2020

Understanding atmospheric processes, such as e.g. cloud and precipitation formation, requires high-resolution water vapor and temperature profile observations particularly in the cloudy boundary-layer. As current observation techniques are limited by low spatial or temporal resolution, the potential of combining microwave radiometer (MWR) with differential absorption radar is investigated by analysing the retrieval information content and retrieval uncertainty. Two radar frequency combinations are analyzed: Ka- and W-band (KaW), available at e.g. Barbados Cloud Observatory, as well as a synthetic combination of G-band frequencies (167 and 175 GHz, G2), simulated using the Passive and Active Microwave TRAnsfer model PAMTRA.

The novel synergistic retrieval approach is based on an optimal estimation retrieval scheme. The absolute humidity profile is retrieved from the MWR K-band brightness temperatures, as well as the Dual-Wavelength Ratio (DWR) signal of the two radars. Evaluating a suite of radiosonde profiles measured at Barbados from 2018, adding the active KaW combination to K-band MWR brightness temperatures increases the information content for the retrieved profile from 3.2 to 3.4 degrees of freedom for signal (DoF). The usage of the higher G2 radar frequencies leads to higher Dual-Wavelength Ratios (DWRs), and, in combination with the MWR, to increased DoF (4.5), decreased retrieval errors, and a more realistic retrieved profile within the cloud layer. Information partitioning among MWR and the radars makes the synergy particularly beneficial: the profile below and within the cloud is restricted by the radar observations, whereas the water vapor above cloud top and the LWP are constrained by the MWR.

Based on selected case studies with single- as well as multi-layered clouds from the EUREC4A campaign, different retrieval configurations will be evaluated based on the resulting retrieval error, as well as the Degrees of Freedom. Tools for customizing the retrieval to the trade wind driven atmosphere will be analyzed by e.g. constraining the humidity profile to saturation within the cloud layer, or making use of a direct inversion approach of the differential attenuation signals.