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At least 883 records · Page 49
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NASA NTRS2023

Global Droughts Connected By Linkages Between Drought Hubs

Quantifying the spatial and interconnected structure of regional to continental scale droughts is one of the unsolved global hydrology problems, which is important for understanding the looming risk of mega-scale droughts and the resulting water and food scarcity and their cascading impact on the worldwide economy. Using a Complex Network analysis, this study explores the topological characteristics of global drought events based on the self-calibrated Palmer Drought Severity Index. Event Synchronization is used to measure the strength of association between the onset of droughts at different spatial locations within the time lag of 1-3 months. The network coefficients derived from the synchronization network indicate a highly heterogeneous connectivity structure underlying global drought events. Drought hotspot regions such as Southern Europe, Northeast Brazil, Australia, and Northwest USA behave as drought hubs that synchronize regionally and with other hubs at inter-continental or even inter-hemispheric scale. This observed affinity among drought hubs is equivalent to the ‘rich-club phenomenon’ in Network Theory, where ‘rich’ nodes (here, drought hubs) are tightly interconnected to form a club, implicating the possibility of simultaneous large-scale droughts over multiple continents.

Drought↗
NASA NTRS2024

Interannual Lightning Variability within the TRMM LIS Dataset Using an ENSO Perspective

The Tropical Rainfall Measuring Mission (TRMM) Lightning Imaging Sensor (LIS) was used to investigate inter-annual variability of lightning from 1998-2014 within the 38° S – 38° N range. Previous studies have indicated that the El-Niño/Southern Oscillation (ENSO) phenomenon is one significant contributor to inter-annual lightning variability, potentially the dominant mechanism on the global scale. This period of 16 years contained four warm- (El Niño), eight cold- (La Niña), and four neutral-phase ENSO years based on the oceanic Niño index. Large magnitude lightning anomalies were found during the warm phase of ENSO, with mean warm-phase anomalies of > 10 Fl (1000 km) −2 min −1 in north-central Africa and Argentina. This includes a +35 Fl (1000 km) −2 min −1 anomaly in Argentina during the 2009 El Niño. In general, large-scale anomalies of thermodynamic properties and upper-atmospheric vertical motion coincided with the lightning anomalies observed in both Africa and South America. The anomaly over north-central Africa, however, was characterized by a 6-week shift in the annual lightning maximum with the warm phase, a result of the more complex environmental response to ENSO over the Sahel. The most consistent ENSO anomalies with appreciable lightning were found in southeastern Africa, northwestern Brazil, central Mexico, and the southern Red Sea. Of these, all but the Mexico region had enhanced lightning with the cold phase and suppressed lightning with the warm phase.

Austin G. Clark↗
NASA NTRS2023

An Urban Drainage Scheme for Large-Scale Flood Models

As flood modeling spatial resolutions get finer, physical processes normally neglected, such as urban drainage, must be accounted for. Here, we describe and evaluate an urban drainage scheme for large-scale flood models. The parameterization accounts for urban imperviousness, and water flow over streets and through a prescribed urban drainage network. A parameter sensitivity analysis is performed during three major extreme floods over Rio de Janeiro city, Brazil, at ∼200 m spatial resolution. Results show that, compared to a hypothetical case without urban drainage, representing a drainage network decreases urban flooding during selected extreme events across Rio de Janeiro by 31–53 %. Such a decrease is caused by an underground water storage of up to 2.5 billion m3 across the city during flood peaks. Underground water storage and transport smooth out and delay peak flows by a few hours over major rivers and channels draining the city. Simulations also indicate that the number of residents exposed to flooding drops by 60–80 %, from ∼5 million to 1–2 million, when an urban drainage system is considered during extreme events. Similar proportions are found for social infrastructure (i.e., schools and hospitals) exposed to flooding. Results reveal that racial minority and low-income populations could disproportionally be exposed to extreme floodings across the city. We conclude that representing urban drainage has a substantial impact on flood exposure and should be accounted for in fine resolution modeling. The proposed scheme is particularly useful in poorly monitored cities and where extreme floods are a frequent hazard yet to be tackled.

Urban drainage↗
NASA NTRS2024

Evaluating Differences Among Crop Models in Simulating Soybean in-Season Growth

Crop models are useful tools for simulating agricultural systems that require continued model development and testing to increase their robustness and improve how they describe our current understanding of processes. Coordinated and “blind” evaluation of multiple models using same protocols and experimental datasets provides unique opportunities to further improve models and enhance their reliability. For soybean [Glycine max (L.) Merr.], there has been limited coordinated multi-model evaluations for the simulation of in-season plant growth dynamics. We evaluated ten dynamic soybean crop models for their simulation of in-season plant growth using data from five experiments conducted in Argentina, Brazil, France, and USA. We evaluated models after a Blind (using only phenology data) and a Full calibration (with in-season and end-of-season variables). Calibration reduced model uncertainty by reducing standard bias for the simulation of in-season variables (biomass, leaf, pod, and stem weights, and leaf area index, LAI). However, we found that most models had difficulty in reproducing leaf growth dynamics, with normalized root mean squared error (nRMSE) of 56% for leaf weight and 43% for LAI (across locations and models after Full calibration). Models with different levels of complexity and experience were capable of simulating final seed yield at maturity with reasonable accuracy (nRMSE of 8–31% after Full calibration). However, the nRMSE for pod weight (of 17–64% after Full calibration) was two-fold larger than that of seed yield. Moreover, the models differed in how they simulated timing from sowing to beginning seed growth (47–93 days) and effective seed filling period (18–54 days), owing to model structural differences in defining the reproductive developmental stages. Overall, we identified the following processes that can benefit from further model improvement: leaf expansion and senescence, reproductive phenology, and partitioning to reproductive growth. Simulation of pod wall tissue and individual seed cohorts is another aspect that many models currently lack. Model improvement can benefit from high-temporal resolution experimental datasets that concurrently account for phenology, plant growth, and partitioning. Further, we recommend collecting reproductive phenology in the field consistent with actual dry matter allocation to organs in the models and collecting multiple observations of seed and pod weight to aid model improvement for simulation of seed growth and yield formation.

Agricultural Model Intercomparison and Improvement↗
NASA NTRS2024

The Economics of Farming Expansion in the Brazilian Cerrado Under Possible Effects of Climate Change

This analysis assesses the financial viability of legally investing in native Cerrado vegetation deforestation for crop production, considering climate change. The study uses data from twelve different crop models based on three different climate models to predict potential future crop yields in cleared land for growing soy and maize. The outcomes show that in many micro-regions, investments in clearing land for crop production would destroy economic value, that is, generate a negative net present value because of low/negative and volatile cashflows driven primarily by future yields as affected by climate. Our analysis was carried out based on present agricultural practices and technology. As climate changes, farmers may adapt their practices, which can lead to more resilient and productive crops, or grow different crops, which could provide better returns on investment in clearing land than the ones resulting from our analysis. Despite various uncertainties, farmers, policy makers and financial institutions should be aware of the climatic and financial risks associated with land clearing in Brazil, mainly in micro-regions in which all scenarios resulted in negative outcomes in the investment analysis.

agricultural expansion↗
NASA NTRSDate not supplied

A Call To Action To Engage The Community To Meet The Challenges That Must Be Tackled To Make Electrified Aircraft Propulsion Real

Technology risk reduction is essential, as it is necessary to demonstrate the potential of Electrified Aircraft Propulsion (EAP). However, more is needed for implementation. The industry is leading EAP by developing a diverse community of novel vehicles from short-haul, small, urban-focused electric vertical takeoff and landing (eVTOL) to regional air mobility (RAM) and hybrid-electric, single-aisle transport category airplanes. There are a variety of novel EAP technologies for each of these novel vehicles. And the industry is not only looking at novel technology to advance the state of the art. Instead, the industry is looking to certify these novel aircraft through their regulatory authorities, such as the US Federal Aviation Administration (FAA), the European Union Aviation Safety Authority (EASA), Transport Canada Civil Aviation (TCCA), and Brazil’s Agência Nacional de Aviação Civil (National Civil Aviation Agency, ANAC), as well as other regulatory authorities. The NASA Electrified Powertrain Flight Demonstration (EPFD) project has partnered with two industry partners to advance integrated MW-class powertrain system technology demonstration that includes an assessment of their regulatory and standards gaps in their technology. The EPFD has conducted a generic regulatory gap analysis of hybrid electric engines that aligns with the industry partners’ efforts. The EPFD regulations and standards team is integrated into the industry standards community. The international industry standards community is wrestling with critical key challenges to certification. While some certification elements are proprietary, several technology elements cut across company propriety in aircraft engines (US 14 CFR Part 33 and EASA CS-E, regulations that only reflect reciprocating and turbine engines). The approach that several of these regulatory authorities have taken is to collaborate to address their challenges. The Certification Management Team (CMT) consists of the EASA, FAA, TCCA, and ANAC, and they have begun to address common questions, such as the Loss of Power Control (LOPC) for electric engines. They have reached out to the standards community to seek answers. The industry standards development organizations (SDO) have also looked ahead to address current regulations and standards gaps. The ASTM has built key committees in its ASTM F44 General Aviation Committee and F39 Aircraft Systems Committee. The SAE has established the E-40 Electric Propulsion and AE-10 High Voltage committees.

Standards↗
NASA NTRSDate not supplied

A Call To Action To Engage The Community To Meet The Challenges That Must Be Tackled To Make Electrified Aircraft Propulsion Real

Technology risk reduction is essential, as it is necessary to demonstrate the potential of Electrified Aircraft Propulsion (EAP). However, more is needed for implementation. The industry is leading EAP by developing a diverse community of novel vehicles from short-haul, small, urban-focused electric vertical takeoff and landing (eVTOL) to regional air mobility (RAM) and hybrid-electric, single-aisle transport category airplanes. There are a variety of novel EAP technologies for each of these novel vehicles. And the industry is not only looking at novel technology to advance the state of the art. Instead, the industry is looking to certify these novel aircraft through their regulatory authorities, such as the US Federal Aviation Administration (FAA), the European Union Aviation Safety Authority (EASA), Transport Canada Civil Aviation (TCCA), and Brazil’s Agência Nacional de Aviação Civil (National Civil Aviation Agency, ANAC), as well as other regulatory authorities. The NASA Electrified Powertrain Flight Demonstration (EPFD) project has partnered with two industry partners to advance integrated MW-class powertrain system technology demonstration that includes an assessment of their regulatory and standards gaps in their technology. The EPFD has conducted a generic regulatory gap analysis of hybrid electric engines that aligns with the industry partners’ efforts. The EPFD regulations and standards team is integrated into the industry standards community. The international industry standards community is wrestling with critical key challenges to certification. While some certification elements are proprietary, several technology elements cut across company propriety in aircraft engines (US 14 CFR Part 33 and EASA CS-E, regulations that only reflect reciprocating and turbine engines). The approach that several of these regulatory authorities have taken is to collaborate to address their challenges. The Certification Management Team (CMT) consists of the EASA, FAA, TCCA, and ANAC, and they have begun to address common questions, such as the Loss of Power Control (LOPC) for electric engines. They have reached out to the standards community to seek answers. The industry standards development organizations (SDO) have also looked ahead to address current regulations and standards gaps. The ASTM has built key committees in its ASTM F44 General Aviation Committee and F39 Aircraft Systems Committee. The SAE has established the E-40 Electric Propulsion and AE-10 High Voltage committees.

Standards↗
NASA NTRSDate not supplied

Natural Language Processing for Extracting Rich Disease Data Aligned To Satellite Meteorological Data

Global climate change is redefining our understanding of how diseases spread. In Sri Lanka, vector-borne diseases such as dengue fever, encephalitis, and leptospirosis historically surged during the monsoon seasons when temperatures were high enough for mosquito eggs to hatch. Unfortunately, due to rising temperatures and more erratic rainfall patterns, mosquito eggs can now hatch year-round and are increasingly unpredictable, leading to an alarmingly increasing number of hospitalizations and deaths. More data is needed to adapt our response to these diseases in an increasingly warmer world. In the contemporary landscape, a wealth of disease information is available, yet accessibility remains limited due to unstructured data formats such as PDFs. Therefore, converting unstructured disease reports into structured formats is necessary for effectively leveraging data. This paper introduces a comprehensive framework for collecting unstructured disease reports and transforming them into analyzable formats. By creating separate models tailored to each data format, we can ensure accuracy compared to general models. These straightforward models enhance accessibility and empower other researchers to use our tools. The returned structured data can then be harnessed for analysis, statistical purposes, and informing evidence-based public health interventions, thus facilitating more informed decision-making in healthcare. We deploy this framework to produce geospatial data for Sri Lanka and Brazil for many different conditions and align these data with satellite environmental data, providing for the first time a structured, aligned powerful dataset for disease modeling.

Open Source Open Science↗
DOE OSTI2014

Nuclear Naval Propulsion: A Feasible Proliferation Pathway?

There is no better time than now to close the loophole in Article IV of the Nuclear Non-proliferation Treaty (NPT) that excludes military uses of fissile material from nuclear safeguards. Several countries have declared their intention to pursue and develop naval reactor technology, including Argentina, Brazil, Iran, and Pakistan, while other countries such as China, India, Russia, and the United States are expanding their capabilities. With only a minority of countries using low enriched uranium (LEU) fuel in their naval reactors, it is possible that a state could produce highly enriched uranium (HEU) under the guise of a nuclear navy while actually stockpiling the material for a nuclear weapon program. This paper examines the likelihood that non-nuclear weapon states exploit the loophole to break out from the NPT and also the regional ramifications of deterrence and regional stability of expanding naval forces. Possible solutions to close the loophole are discussed, including expanding the scope of the Fissile Material Cut-off Treaty, employing LEU fuel instead of HEU fuel in naval reactors, amending the NPT, creating an export control regime for naval nuclear reactors, and forming individual naval reactor safeguards agreements.

export controls↗
DOE OSTI2016

The ARM Climate Research Facility in the Amazon Basin. Final Report

The Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) Experiment was carried out in the environs of Manaus, Brazil, in the central region of the Amazon basin during two years from 1 January 2014 through 31 December 2015. The experiment focused on the complex interactions among vegetation, atmospheric chemistry, and aerosol production on the one hand and their connections to aerosols, clouds, and precipitation on the other. The objective was to understand and quantify these linked processes, first under natural conditions to obtain a baseline and second when altered by the effects of human activities. To this end, the pollution plume from the Manaus metropolis, superimposed on the background conditions of the central Amazon basin, served as a natural laboratory. The present paper, as Introduction to the GoAmazon2014/5 Special Issue, presents the context and motivation of the GoAmazon2014/5 Experiment. The nine research sites, including the characteristics and instrumentation of each site, are presented. The sites range from time point zero (T0) upwind of the pollution, to T1 in the midst of the pollution, to T2 just downwind of the pollution, to T3 furthest downwind of the pollution (70 km). In addition to the ground sites, a low-altitude G-159 Gulfstream I (G1) observed the atmospheric boundary layer and low clouds, and a high-altitude Gulfstream G550 (HALO) operated in the free troposphere. During the two-year experiment, two Intensive Operating Periods (IOP1 and IOP2) also took place that included additional specialized research instrumentation at the ground sites as well as flights of the two aircraft. GoAmazon2014/5 IOP1 was carried out from 1 February to 31 March 2014 in the wet season. GoAmazon2014/5 IOP2 was conducted from 15 August to 15 October 2014 in the dry season. The G1 aircraft flew during both IOP1 and IOP2, and the HALO aircraft flew during IOP2. In the context of the Amazon basin, the two IOPs also correspond to the clean and biomass burning seasons, respectively. The Manaus plume is present year round, and it is transported by prevailing northeasterly and easterly winds in the wet and dry seasons, respectively. This Introduction also organizes information relevant to many papers in the Special Issue. Information is provided on the vehicle fleet, power plants, and industrial activities of Manaus. The mesoscale and synoptic meteorology relevant to the two IOPs is presented. Regional and long-range transport of emissions for the two IOPs is discussed based on satellite observations across South America and Africa. Fire locations throughout the airshed are detailed. In conjunction with the context and motivation of GoAmazon2014/5, as presented herein in this Introduction, research articles published in this Special Issue are anticipated in the near future to describe the detailed results and findings of GoAmazon2014/5.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Barotrauma em peixes em usinas hidrelétricas: ferramentas para o estudo

The main source of electric power generation in Brazil comes from hydropower plants, nevertheless, the installed power is expected to raise 56.8%, reaching a total of 116,000 MW at the year 2020. The increase at the hydroelectric sector will be responsible for a series of fish community impacts. One of the impacts over the fish community is related to fish kills due to downstream passage through turbines or fish entrance at the draft tube from the tailrace. Usually when there is a maneuver and the turbine stops, fish get attracted and enter the draft tube and, just as the downstream passage through a turbine, when the turbine starts, a rapid decompression occurs and can cause barotrauma. When such events happen, according to Boyle’s law (P1V1=P2V2), swim bladder volume expands at the same rate that the pressure decreases, which can lead to the organ’s rupture.

barotrauma↗
DOE OSTI2016

Small Particles, Big Science: The International LBNF/DUNE Project

Neutrinos are the most abundant matter particles in the universe, yet very little is known about them. This animation shows how the Department of Energy’s Long-Baseline Neutrino Facility will power the Deep Underground Neutrino Experiment to help scientists understand the role neutrinos play in the universe. DUNE will also look for the birth of neutron stars and black holes by catching neutrinos from exploding stars. More than 800 scientists from 150 institutions in 27 countries are working on the LBNF/DUNE project, including Armenia, Belgium, Brazil, Bulgaria, Canada, Colombia, Czech Republic, Finland, France, Greece, India, Iran, Italy, Japan, Madagascar, Mexico, Netherlands, Peru, Poland, Romania, Russia, Spain, Switzerland, Turkey, Ukraine, United Kingdom, USA.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Lidar Comparison for GoAmazon 2014/15 Field Campaign Report

The Observations and Modeling of the Green Ocean Amazon 2014/15 (GoAmazon 2014/15) experiment uses the city of Manaus, Amazonas (AM), Brazil, in the setting of the surrounding green ocean as a natural laboratory for understanding the effects of present and future anthropogenic pollution on the aerosol and cloud life cycle in the tropics. The U.S. Department of Energy (DOE) supported this experiment through the deployment of the Atmospheric Radiation Measurement (ARM) Climate Research Facility’s first Mobile Facility (AMF-1) in the city of Manacapuru, which is 100 km downwind of Manaus, from January 1 2014 to December 31 2015. During the second Intensive Operational Period (IOP) from August 15 to October 15 2014, three lidar systems were operated simultaneously at different experimental sites, and an instrument comparison campaign was carried out during the period October 4 to 10, during which the mobile lidar system from Instituto de Pesquisas Energéticas e Nucleares-Universidade de São Paulo was brought from the T2 site (Iranduba) to the other sites (T3 [Manacapuru] and then T0e-Embrapa). In this report we present the data collected by the mobile lidar system at the DOE-ARM site and compare its measurements with those from the micro-pulse lidar system running at that site.

Amazon, cloud life cycle in the tropics, aerosols,↗
DOE OSTI2016

Observations and Modeling of the Green Ocean Amazon 2014/15: Transmission Electron Microscopy Analysis of Aerosol Particles Field Campaign Report

During two Intensive Operational Periods (IOP), we collected samples at 3-hour intervals for transmission electron microscopy analysis. The resulting transmission electron microscopy images and compositions were analyzed for the samples of interest. Further analysis will be done especially for the plume of interest. We found solid spherical organic particles from rebounded samples collected with Professor Scot Martin’s group (Harvard University). Approximately 30% of the rebounded particles at 95% relative humidity were spherical organic particles. Their sources and formation process are not known, but such spherical particles could be solid and will have heterogeneous chemical reactions. We observed many organic particles that are internally mixed with inorganic elements such as potassium and nitrogen. They are either homogeneously mixed or have inorganic cores with organic aerosol coatings. Samples collected from the Manaus, Brazil, pollution plume included many nano-size soot particles mixed with organic material and sulfate. Aerosol particles from clean periods included organic aerosol particles, sulfate, sea salt, dust, and primary biogenic aerosol particles. There was more dust, primary biogenic aerosol, and tar balls in samples taken during IOP1 than those taken during IOP2. Many dust particles were found between March 2 and 3.

spherical organic particles, Manaus pollution plum↗
DOE OSTI2016

Understanding How Biomass Burning Impacts Climate Change

Biomass burning in Africa is creating a plume that spreads across the Atlantic Ocean all the way to Brazil. Allison Aiken, a research scientist at Los Alamos National Laboratory, collects data about the black carbon aerosols within this plume and their impact on the environment to help improve global climate modeling. A leader in energy science, Los Alamos develops climate models in support of the Laboratory’s mission to strengthen the nation’s energy security. Allison’s work is part of FIDO, a field operations team funded by the Energy Department’s Office of Science’s ARM Climate Research Facility.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

The Science of the Deep Underground Neutrino Experiment (DUNE)

This 4-minute animation shows how the international Deep Underground Neutrino Experiment will help scientists understand how the universe works. DUNE will use a huge particle detector a mile underground to embark on a mission with three major science goals: 1.) Study an intense, 1,300-kilometer-long neutrino beam to discover what happened after the big bang: Are neutrinos the reason the universe is made of matter? 2.) Use 70,000 tons of liquid argon to look for proton decay and move closer to realizing Einstein’s dream of a unified theory of matter and energy. 3.) Catch neutrinos from a supernova to watch the formation of neutron stars and black holes in real time. About 1,000 scientists from 160 institutions in 30 countries are working on the Deep Underground Neutrino Experiment, hosted at the Department of Energy’s Fermi National Accelerator Laboratory and South Dakota’s Sanford Underground Research Facility. DUNE collaborators come from institutions in Armenia, Brazil, Bulgaria, Canada, Chile, China, Colombia, Czech Republic, Finland, France, Greece, India, Iran, Italy, Japan, Madagascar, Mexico, Netherlands, Peru, Poland, Romania, Russia, South Korea, Spain, Sweden, Switzerland, Turkey, Ukraine, United Kingdom, and the United States of America.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Multi-scale processes driving tropical convection and influence of the aerosol (Final Technical Report)

This DOE GoAmazon collaborative project between scientists in the US and Brazil addresses fundamental processes that drive tropical deep convection including aerosol effects. The results provide guidance for improving the parameterizations of cloud and aerosol effects by increasing the knowledge of processes at work in tropical convection, especially over tropical land. Highlights include: • GoAmazon2014/5 observations permitted, for the first time, a comprehensive evaluation of the strong relationship between lower free tropospheric moisture and deep convective onset over the Amazon (Schiro et al. 2016, JAS; Schiro et al. 2018b, PNAS; Chakraborty et al. 2018, ACP; Schiro and Neelin 2018c). A set of diagnostics for deep convective onset has been established using data from the GoAmazon2014/5 campaign (Schiro et al. 2016, JAS), highlighting similarities and differences between the convective transition statistics over tropical land versus corresponding statistics from ARM campaigns in the tropical Western Pacific. The initial set of diagnostics has been provided as a module to be incorporated into the ARM Diagnostics Package of Shaocheng Xie and coworkers, which is being integrated into the PCMDI and E3SM diagnostics packages. Additionally, a set of downdraft diagnostics to inform model parameterizations has been developed (Schiro and Neelin 2018a, ACP). • These diagnostics have been used in constraining the behavior of modeled convective parameterizations. This includes using them with parameter perturbation experiments in the Community Earth System Model to show which parameter ranges are consistent with observed onset statistics, and to show that the primary causal direction of the water vapor-precipitation relationship is via the impact of mixing processes and free tropospheric moisture on convection (Kuo et al. 2017, JAS). Lintner et al. (2017, GRL) used this impact of free tropospheric moisture to systematically analyze issues in the simulation of Amazon rainfall in the CMIP5 model ensemble. • Leveraging the multi-instrument GoAmazon observations, Schiro et al. (2018, PNAS) are able to provide for the first time an empirical mixing using radar wind profiler data that provides a good predictor of precipitation for both mesoscale convective systems and smaller-scale convection. In addition, buoyancy estimated from these results is a good predictor of precipitation across the seasonal and diurnal cycles (Schiro and Neelin 2018c, JAS) and permits the effects of aerosols to be distinguished from those of the thermodynamic environment in the transition to deep convection (Chakraborty et al. 2018, ACP). • Placing the GoAmazon campaign in a larger context, in collaboration with U. São Paulo investigators, Rehbein et al. (2018) analyzed the characteristics of the mesoscale convective systems (MCS) that affect Amazon rainfall, including origins, lifetimes, propagation speed and displacement. de Barros Soares et al. (2017) establish statistically significant observed warming trends over much of South America and are able to attribute the origin of this to anthropogenic forcing based on the agreement of climate model simulations with and without anthropogenic forcings. This analysis left open the attribution of precipitation trends due to large natural variability. Barkhardorian et al. (2018) provide evidence indicating that the observed regional precipitation decrease and drying during recent over northern South America during recent austral springs will continue and intensify in the course of unfolding anthropogenic climate change.

54 ENVIRONMENTAL SCIENCES↗