Most recent 40 articles: American Geophysical Union
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The Western Antarctic ice sheet may be in trouble - American Geophysical Union (Aug 29, 2021) |
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Aug 29, 2021 · Working off-campus? Learn about our remote access options
Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand
Correspondence to:
N. R. Golledge,
nicholas.golledge@vuw.ac.nz
College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
School of Geography and Environmental Sciences, University of Ulster, Coleraine, UK
Center for Climatic Research, Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, WI, USA
Department of Geoscience, University of Wisconsin-Madison, Madison, WI, USA
School of Biological, Earth and Environmental ... Read more ...
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Coupling of Clouds and Tropospheric Relative Humidity in the Tropical Western Atlantic: Insights From Multisatellite Observations - American Geophysical Union (Apr 16, 2020) |
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Apr 16, 2020 · We investigated the interactions between clouds and moisture at the diurnal scale in the Western Atlantic trade winds region. Profiles of tropospheric relative humidity from the SAPHIR/Megha-Tropiques sounder are combined with cloud categories obtained from geostationary satellites. In winter, the midtroposphere undergoes strong daytime drying due to air masses coming from the colder upper troposphere. The moistening near the surface triggered by solar radiation precludes the development of low-level clouds. At night rising moist air in the upper troposphere triggers the formation of high-altitude clouds and favors their presence. In summer, daytime high-altitude clouds shield the ... Read more ...
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QBO Changes in CMIP6 Climate Projections - American Geophysical Union (Apr 16, 2020) |
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Apr 16, 2020 · A generally under appreciated development introduced with the CMIP6 multimodel ensemble is the increased number of models representing stratospheric processes, with 15 out 30 models now able to simulate realistic QBO-like behavior in the equatorial stratosphere during the historical period (Richter, Anstey, et al., 2020). The CMIP6 simulations therefore provide a new opportunity to quantify, with increased confidence, QBO changes seen in state-of-the-art climate projections. However, several of the model runs' diagnostics required for analyzing the mechanisms driving the QBO changes are not currently available in the CMIP6 international archive. Thus, the aim here is to focus on ... Read more ...
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Tectonic Uplift Destabilizes Subsea Gas Hydrate: A Model Example From Hikurangi Margin, New Zealand - American Geophysical Union (Apr 16, 2020) |
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Apr 16, 2020 · Rising ocean temperatures and falling sea level are commonly cited as mechanisms of marine gas hydrate destabilization. More recently, uplift - both isostatic and tectonic - has been invoked. However, the effect of tectonic shortening and uplift on gas hydrate stability zone extent has not been validated via integrated computational modeling. Here, modeling along the Hikurangi margin of New Zealand illustrates the mechanism of tectonic uplift as a driver of gas hydrate destabilization. We simulate how tectonic uplift and shortening affect the presence and decrease the extent of a gas hydrate stability zone. We suggest that resultant gas hydrate destabilization in the marine realm ... Read more ...
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How Variable Is Mixing Efficiency in the Abyss? - Ijichi - 2020 - Geophysical Research Letters - Wiley Online Library - American Geophysical Union (Apr 14, 2020) |
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Apr 14, 2020 · Mixing efficiency is an important turbulent flow property in fluid dynamics, whose variability potentially affects the large-scale ocean circulation. However, there are several confusing definitions. Here we compare and contrast patch-wise versus bulk estimates of mixing efficiency in the abyss by revisiting data from previous extensive field surveys in the Brazil Basin. Observed patch-wise efficiency is highly variable over a wide range of turbulence intensity. Bulk efficiency is dominated by rare extreme turbulence events. In the case where enhanced near-bottom turbulence is thought to be driven by breaking of small-scale internal tides, the estimated bulk efficiency is 20%, close ... Read more ...
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Sensitivity of Tropospheric Ozone Over the Southeast USA to Dry Deposition - Baublitz - 2020 - Geophysical Research Letters - Wiley Online Library - American Geophysical Union (Apr 13, 2020) |
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Apr 13, 2020 · Dry deposition (DD) is a major loss process for tropospheric ozone and some reactive nitrogen and carbon precursors. We investigate the response of summertime ozone and its production chemistry over the Southeast United States (USA) to variability in this sink. Turning off DD of oxidized nitrogen, ozone, or all species over the United States in the Geophysical Fluid Dynamics Laboratory AM3 model increases regional mean surface ozone by 5, 18, or 25 ppb, respectively. Additional sensitivity simulations demonstrate that, assuming linearity, surface ozone has a similar sensitivity to ozone DD as to NOx emissions. Trends in ozone production efficiency derived from observed relationships ... Read more ...
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Contribution of Electroactive Humic Substances to the Iron-Binding Ligands Released During Microbial Remineralization of Sinking Particles - American Geophysical Union (Apr 11, 2020) |
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Apr 11, 2020 · Iron is a key micronutrient in seawater, but concentrations would be negligible without the presence of organic ligands. The processes influencing the ligand pool composition are poorly constrained, limiting our understanding of the controls on dissolved iron distributions. To address this, the release of iron and iron-binding ligands during the microbial remineralization of sinking particles was investigated by deploying in situ particle interceptor/incubator devices at subsurface sites in the Mediterranean Sea and Subantarctic. Analyses revealed that the pool of released ligands was largely dominated by electroactive humic substances (74 ± 28%). The release of ligands during ... Read more ...
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Diagnosing Transient Response to CO - American Geophysical Union (Apr 11, 2020) |
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Apr 11, 2020 · A climate model emulator that mimics an ensemble of state-of-the-art coupled climate models has been used for probabilistic climate projections. To emulate and compare the latest and previous multimodel ensembles, this study establishes a new method to diagnose a set of parameters of effective radiative forcing, feedback, and impulse response functions by fitting a minimal emulator to time series of individual models in response to step- and ramp-shaped CO2 forcing up to a quadrupling concentration level. The diagnosed CO2 forcing is scaled down to a doubling level, leading to an unbiased estimate of equilibrium climate sensitivity. The average climate sensitivity of the latest ... Read more ...
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Grounding Line Retreat of Denman Glacier, East Antarctica, Measured With COSMO-SkyMed Radar Interferometry Data - American Geophysical Union (Apr 08, 2020) |
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Apr 08, 2020 · Denman Glacier, East Antarctica, holds an ice volume equivalent to a 1.5 m rise in global sea level. Using satellite radar interferometry from the COSMO-SkyMed constellation, we detect a 5.4 ± 0.3 km grounding line retreat between 1996 and 2017–2018. A novel reconstruction of the glacier bed topography indicates that the retreat proceeds on the western flank along a previously unknown 5 km wide, 1,800 m deep trough, deepening to 3,400 m below sea level. On the eastern flank, the grounding line is stabilized by a 10 km wide ridge. At tidal frequencies, the grounding line extends over a several kilometer-wide grounding zone, enabling warm ocean water to melt ice at critical locations ... Read more ...
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Magnitudes and Spatial Patterns of Interdecadal Temperature Variability in CMIP6 - American Geophysical Union (Apr 08, 2020) |
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Apr 08, 2020 · Attribution and prediction of global and regional warming requires a better understanding of the magnitude and spatial characteristics of internal global mean surface air temperature (GMST) variability. We examine interdecadal GMST variability in Coupled Modeling Intercomparison Projects, Phases 3, 5, and 6 (CMIP3, CMIP5, and CMIP6) preindustrial control (piControl), last millennium, and historical simulations and in observational data. We find that several CMIP6 simulations show more GMST interdecadal variability than the previous generations of model simulations. Nonetheless, we find that 100-year trends in CMIP6 piControl simulations never exceed the maximum observed warming ... Read more ...
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A Sea Surface Height Perspective on El Niño Diversity, Ocean Energetics, and Energy Damping Rates - American Geophysical Union (Apr 06, 2020) |
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Apr 06, 2020 · Ocean energetics is a useful framework for understanding El Niño–Southern Oscillation; however, its key element, available potential energy (APE), requires accurate ocean subsurface data that are hard to measure. Here, we describe a sea surface height-based index, SSHI, that accurately captures APE variations and can be easily computed from satellite observations. Using SSHI, we obtain an observation-based estimate of the APE damping timescale of approximately 1.7 years, slightly longer than previous ocean reanalysis-based estimates. Furthermore, SSHI serves as an indicator for El Niño “flavors” while recording the relative strength of the thermocline feedback. SSHI captures a ... Read more ...
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El Niño-Driven Oxygenation Impacts Peruvian Shelf Iron Supply to the South Pacific Ocean - American Geophysical Union (Apr 06, 2020) |
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Apr 06, 2020 · Upwelling ocean currents associated with oxygen minimum zones (OMZs) supply nutrients fuelling intense marine productivity. Perturbations in the extent and intensity of OMZs are projected in the future, but it is currently uncertain how this will impact fluxes of redox-sensitive trace metal micronutrients to the surface ocean. Here we report seawater concentrations of Fe, Mn, Co, Cd, and Ni alongside the redox indicator iodide/iodate in the Peruvian OMZ during the 2015 El Niño event. The El Niño drove atypical upwelling of oxygen-enriched water over the Peruvian Shelf, resulting in oxidized iodine and strongly depleted Fe (II), total dissolved Fe, and reactive particulate Fe ... Read more ...
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From the Ground to Space: Using Solar-Induced Chlorophyll Fluorescence to Estimate Crop Productivity - American Geophysical Union (Apr 06, 2020) |
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Apr 06, 2020 · Timely and accurate monitoring of crops is essential for food security. Here, we examine how well solar-induced chlorophyll fluorescence (SIF) can inform crop productivity across the United States. Based on tower-level observations and process-based modeling, we find highly linear gross primary production (GPP):SIF relationships for C4 crops, while C3 crops show some saturation of GPP at high light when SIF continues to increase. C4 crops yield higher GPP:SIF ratios (30–50%) primarily because SIF is most sensitive to the light reactions (does not account for photorespiration). Scaling to the satellite, we compare SIF from the TROPOspheric Monitoring Instrument (TROPOMI) against ... Read more ...
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Homogenization of Dissolution and Enhanced Precipitation Induced by Bubbles in Multiphase Flow Systems - American Geophysical Union (Apr 06, 2020) |
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Apr 06, 2020 · Multiphase flow is ubiquitous in subsurface energy applications and natural processes, such as oil recovery, CO2 sequestration, and water flow in soils. Despite its importance, we still lack a thorough understanding of the coupling of multiphase flow and reaction of transported fluids with the confining media, including rock dissolution and mineral precipitation. Through the use of geomaterial microfluidic flow experiments and high-performance computer simulations, we identify key pore-scale mechanisms that control this coupling. We compare the reactivity of fractured limestone with CO2-saturated brine (single phase) and a mixture of supercritical (sc) CO2 and CO2-saturated brine ... Read more ...
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Plant Water Uptake Thresholds Inferred From Satellite Soil Moisture - American Geophysical Union (Apr 06, 2020) |
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Apr 06, 2020 · Empirical functions are widely used in hydrological, agricultural, and Earth system models to parameterize plant water uptake. We infer soil water potentials at which uptake is downregulated from its well-watered rate and at which uptake ceases, in biomes with <60% woody vegetation at 36-km grid resolution. We estimate thresholds through Bayesian inference using a stochastic soil water balance framework to construct theoretical soil moisture probability distributions consistent with empirical distributions derived from satellite soil moisture observations. The global median Nash–Sutcliffe efficiency between empirical soil moisture distributions and theoretical distributions using ... Read more ...
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The Impact of Rain on Ocean Surface Waves and Currents - American Geophysical Union (Apr 06, 2020) |
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Apr 06, 2020 · Precipitation is an important component of the interaction between Earth's atmosphere and oceans, modifying air-sea fluxes of momentum, heat, and gas. It has been hypothesized that rain's suppression of ocean surface gravity waves and centimeter-scale wave enhancement should alter the nature of air-sea momentum flux, resulting in increased near-surface current. Here, we use field observations to describe this impact and measure the very near-surface current response to rainfall. During heavy rain, surface-roughening ring waves were generated and longer gravity waves were suppressed; immediately following, the magnitude of the near-surface current increased in response to wind ... Read more ...
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Uncoupled El Niño Warming - American Geophysical Union (Apr 06, 2020) |
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Apr 06, 2020 · In light of a warming climate, the complexity of the El Niño/Southern Oscillation (ENSO) makes its prediction a challenge. In addition to various flavors of ENSO, oceanic warming in the central and eastern tropical Pacific is not always accompanied by corresponding atmospheric anomalies; that is, the atmosphere and ocean remain uncoupled. Such uncoupled warm events as happened in 1979, 2004, 2014, and 2018 are rare and represent an unusual form of ENSO diversity. A weaker zonal sea surface temperature anomaly gradient across the tropical Pacific compared to a conventional El Niño may partially account for the decoupling. Also, the uncoupled warm events typically start late in the ... Read more ...
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Climate Change and Social Unrest: A 6,000-Year Chronicle From the Eastern Mediterranean - American Geophysical Union (Apr 04, 2020) |
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Apr 04, 2020 · The history of the Eastern Mediterranean is punctuated by major crises that have influenced many of the region's established socioeconomic models. Recent studies have underscored the role of drought and temperature oscillations in driving changes but attempts to quantify their magnitude remain equivocal, hindering long-term assessments of the potential interplay between climate and society. Here, we fill this knowledge gap using a 6,000-year pollen-based reconstruction of temperature and precipitation from Hala Sultan Tekke, Cyprus. We find that major social changes and plague outbreaks often occurred in tandem with cooler climate conditions, with anomalies ranging from -3 ± 0.4 °C ... Read more ...
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Enhanced El Niño–Southern Oscillation Variability in Recent Decades - American Geophysical Union (Apr 04, 2020) |
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Apr 04, 2020 · The El Niño–Southern Oscillation (ENSO) represents the largest source of year-to-year global climate variability. While Earth system models suggest a range of possible shifts in ENSO properties under continued greenhouse gas forcing, many centuries of preindustrial climate data are required to detect a potential shift in the properties of recent ENSO extremes. Here we reconstruct the strength of ENSO variations over the last 7,000 years with a new ensemble of fossil coral oxygen isotope records from the Line Islands, located in the central equatorial Pacific. The corals document a significant decrease in ENSO variance of ~20% from 3,000 to 5,000 years ago, coinciding with changes in ... Read more ...
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The Aquitaine Shelf Edge (Bay of Biscay): A Primary Outlet for Microbial Methane Release - American Geophysical Union (Apr 04, 2020) |
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Apr 04, 2020 · A few thousand (2,612) seeps are releasing microbial methane bubbles from the seafloor at the Aquitaine Shelf edge (Bay of Biscay) at shallow water depths (140–220 m). This methane contributes to the formation of meter-scale subcircular carbonate structures, which are (sub)outcropping over 375 km2. Based on in situ flow rate measurements and acoustic data, and assuming steady and continuous fluxes over time, the methane entering the water column is estimated at 144 Mg/yr. Microbial methane circulation has been ongoing for at least a few thousand years. This discovery highlights the importance of microbial methane generation, disconnected from deep thermogenic sources and gas ... Read more ...
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Delineating the Seasonally Modulated Nonlinear Feedback Onto ENSO From Tropical Instability Waves - American Geophysical Union (Apr 02, 2020) |
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Apr 02, 2020 · Tropical instability waves (TIWs), the dominant form of eddy variability in the tropics, have a peak period at about 5 weeks and are strongly modulated by both the seasonal cycle and El Niño–Southern Oscillation (ENSO). In this study, we first demonstrated that TIW-induced nonlinear dynamical heating (NDH) is basically proportional to the TIW amplitude depicted by a complex index for TIW. We further delineated that this NDH, capturing the seasonally modulated nonlinear feedback of TIW activity onto ENSO, is well approximated by a theoretical formulation derived analytically from a simple linear stochastic model for the TIW index. The results of this study may be useful for the ... Read more ...
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Dynamic Rupture Simulations of the M6.4 and M7.1 July 2019 Ridgecrest, California, Earthquakes - Lozos - 2020 - Geophysical Research Letters - Wiley Online Library - American Geophysical Union (Apr 02, 2020) |
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Apr 02, 2020 · The largest earthquakes of the 2019 Ridgecrest, California, sequence were a M 6.4 left-lateral rupture followed 34 hr later by a M 7.1 on a perpendicular right-lateral fault. We use dynamic rupture modeling to address the questions of why the first earthquake did not propagate through the right-lateral fault in one larger event, whether stress changes from the M 6.4 were necessary for the M 7.1 to occur, and how the Ridgecrest earthquakes affected the nearby Garlock Fault. We find that dynamic clamping and shear stress reduction confined surface rupture in the M 6.4 to the left-lateral fault. We also find that stress changes from the M 6.4 were not necessary to allow a M 7.1 on the ... Read more ...
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Increased Subglacial Sediment Discharge in a Warming Climate: Consideration of Ice Dynamics, Glacial Erosion, and Fluvial Sediment Transport - American Geophysical Union (Apr 02, 2020) |
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Apr 02, 2020 · We evaluate changes to subglacial sediment discharge during glacier retreat by considering ice dynamics, bedrock erosion, and sediment transport processes. Coupling these components together within a single framework, we simulate sediment discharge from synthetic alpine glaciers experiencing accelerated glacier melt for 100 years. We find that sediment discharge increases by about 8 times the steady glacier values by the end of the simulation. The enhanced sediment discharge persists through peak water discharge and despite annual bedrock erosion volume decreasing by approximately 30% from the initial value. The greater sediment discharge results from increased melt at the glaciers' ... Read more ...
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The Roles of the Atmosphere and Ocean in Driving Arctic Warming Due to European Aerosol Reductions - American Geophysical Union (Apr 02, 2020) |
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Apr 02, 2020 · Clean air policies can have significant impacts on climate in remote regions. Previous modeling studies have shown that the temperature response to European sulfate aerosol reductions is largest in the Arctic. Here we investigate the atmospheric and ocean roles in driving this enhanced Arctic warming using a set of fully coupled and slab-ocean simulations (specified ocean heat convergence fluxes) with the Norwegian Earth system model (NorESM), under scenarios with high and low European aerosol emissions relative to year 2000. We show that atmospheric processes drive most of the Arctic response. The ocean pathway plays a secondary role inducing small temperature changes mostly in the ... Read more ...
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Water Security Assessment for the Contiguous United States Using Water Footprint Concepts - American Geophysical Union (Apr 02, 2020) |
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Apr 02, 2020 · Water security is tightly connected with the food security, ecological health, and economic prosperity of a region. In this study, a comprehensive water security assessment based on water footprint concepts from 1995 to 2015 was performed for the counties located in the Contiguous States of the Unites States. The availability of blue water (e.g., surface water) is comparatively less in the western river basins, and most of the rainfed agricultural lands in the eastern United States were characterized by the lower levels of green water (e.g., root zone soil moisture) storage. This integrated assessment of the water security indicators can directly map the critical regions and reveal ... Read more ...
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Joint Trends in Flood Magnitudes and Spatial Extents Across Europe - American Geophysical Union (Apr 01, 2020) |
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Apr 01, 2020 · The magnitudes of river floods in Europe have been observed to change, but their alignment with changes in the spatial coverage or extent of individual floods has not been clear. We analyze flood magnitudes and extents for 3,872 hydrometric stations across Europe over the past five decades and classify each flood based on antecedent weather conditions. We find positive correlations between flood magnitudes and extents for 95% of the stations. In central Europe and the British Isles, the association of increasing trends in magnitudes and extents is due to a magnitude-extent correlation of precipitation and soil moisture along with a shift in the flood generating processes. The ... Read more ...
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Predictability of the Super IOD Event in 2019 and Its Link With El Niño Modoki - American Geophysical Union (Apr 01, 2020) |
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Apr 01, 2020 · A positive Indian Ocean Dipole (IOD) in 2019 that reached the level of the strongest events occurred in 1994 and 1997 and caused disasters in countries around the Indian Ocean. Using a quasi real-time ensemble seasonal prediction system based on the Scale Interaction Experiment-Frontier climate model, its occurrence was predicted a few seasons ahead and the possible impacts were warned by overcoming the so-called winter predictability barrier. The successful prediction of such a super event at long lead time may contribute to reducing the risks of socioeconomic losses by introducing suitable measures for adaptation. Here, we have investigated possible sources of the successful ... Read more ...
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Structural Variability Within the Kane Oceanic Core Complex From Full Waveform Inversion and Reverse Time Migration of Streamer Data - American Geophysical Union (Apr 01, 2020) |
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Apr 01, 2020 · The origin and distribution of the gabbroic bodies provide crucial information to understand the formation and evolution processes of the oceanic core complexes (OCCs). Nevertheless, images of the shape of the gabbroic bodies across the domes and gabbroic intrusion into the mantle have remained elusive. High-resolution acoustic early-arrival full waveform inversion tomography models obtained along and across the Kane OCC characterize the detailed lateral variability in structure and composition of the upper ~2 km of this well-developed OCC. Reverse time migration images show the gabbroic plutons embedded in mantle rocks are seismically transparent, while more reflective sections ... Read more ...
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Tropical Belt Width Proportionately More Sensitive to Aerosols Than Greenhouse Gases - American Geophysical Union (Apr 01, 2020) |
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Apr 01, 2020 · The tropical belt has widened during the last several decades, and both internal variability and anthropogenic forcings have contributed. Although greenhouse gases and stratospheric ozone depletion have been implicated as primary anthropogenic drivers of tropical expansion, the possible role of other drivers remains uncertain. Here, we analyze the tropical belt width response to idealized perturbations in multiple models. Our results show that absorbing black carbon (BC) aerosol drives tropical expansion, and scattering sulfate aerosol drives contraction. BC, especially from Asia, is more efficient per unit radiative forcing than greenhouse gases in driving tropical expansion, ... Read more ...
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Arctic Sea Ice Loss as a Potential Trigger for Central Pacific El Niño Events - American Geophysical Union (Mar 31, 2020) |
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Mar 31, 2020 · Little attention has been paid to the influence of Arctic sea ice loss on climate variability in the tropical Pacific. By analyzing observational data sets, we hypothesized that anomalous Arctic sea ice concentration variations have the potential to influence tropical Pacific sea surface temperature (SST) variability via atmosphere-ocean coupled processes in the eastern subtropical North Pacific. To test this hypothesis, we conducted idealized model experiments with 15 ensembles in which historical SSTs for 1951–2016 were restored in the Arctic only with different initial conditions. We found that a positive phase of North Pacific Oscillation-like atmospheric circulation, which is ... Read more ...
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Channel Network Control on Seasonal Lake Area Dynamics in Arctic Deltas - American Geophysical Union (Mar 31, 2020) |
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Mar 31, 2020 · The abundant lakes dotting arctic deltas are hotspots of methane emissions and biogeochemical activity, but seasonal variability in lake extents introduces uncertainty in estimates of lacustrine carbon emissions, typically performed at annual or longer time scales. To characterize variability in lake extents, we analyzed summertime lake area loss (i.e., shrinkage) on two deltas over the past 20 years, using Landsat-derived water masks. We find that monthly shrinkage rates have a pronounced structured variability around the channel network with the shrinkage rate systematically decreasing farther away from the channels. This pattern of shrinkage is predominantly attributed to a ... Read more ...
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Is There a Nascent Plate Boundary in the Northern Indian Ocean? - American Geophysical Union (Mar 31, 2020) |
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Mar 31, 2020 · The northern Indian Ocean has been widely recognized as an area of broadly distributed deformation within the composite India-Australia-Capricorn plate, hosting several diffuse boundary zones and a diffuse triple junction. The occurrence, along reactivated fracture zones, of the exceptionally large (Mw = 8.6 and Mw = 8.2) 2012 Wharton Basin strike-slip earthquakes, however, questions whether this composite plate is breaking apart along a discrete boundary. Using recent bathymetric and seismic data, we analyze the most prominent fracture zone (F6a), whose structural trace is particularly well expressed. We identify 60 kilometric-scale pull-apart basins with geometric properties ... Read more ...
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Sugar, Gravel, Fish, and Flowers: Dependence of Mesoscale Patterns of Trade-Wind Clouds on Environmental Conditions - American Geophysical Union (Mar 26, 2020) |
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Mar 26, 2020 · Trade-wind clouds exhibit a large diversity of spatial organizations at the mesoscale. Over the tropical western Atlantic, a recent study has visually identified four prominent mesoscale patterns of shallow convection, referred to as flowers, fish, gravel, and sugar. We show that these four patterns can be identified objectively from satellite observations by analyzing the spatial distribution of infrared brightness temperatures. By applying this analysis to 19 years of data, we examine relationships between cloud patterns and large-scale environmental conditions. This investigation reveals that on daily and interannual timescales, the near-surface wind speed and the strength of the ... Read more ...
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Arctic Sea-Ice Variability During the Instrumental Era - American Geophysical Union (Mar 24, 2020) |
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Mar 24, 2020 · Arctic sea-ice extent (SIE) has declined drastically in recent decades, yet its evolution prior to the satellite era is highly uncertain. Studies using SIE observations find little variability prior to the 1970s; however, these reconstructions are based on limited data, especially prior to the 1950s. We use ensemble Kalman filter data assimilation of surface air temperature observations with Last Millennium climate model simulations to create a fully gridded Arctic sea-ice concentration reconstruction from 1850 to 2018 and investigate the evolution of Arctic SIE during this period. We find a decline of ~1.25×106 km2 during the early 20th-century warming (1910–1940). The 25-year ... Read more ...
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Different Responses of Tropical Cyclone Tracks Over the Western North Pacific and North Atlantic to Two Distinct Sea Surface Temperature Warming Patterns - American Geophysical Union (Mar 24, 2020) |
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Mar 24, 2020 · How future tropical cyclone (TC) activity could change under global warming is enormously important to society, which has been widely assessed using state-of-the-art climate models. However, these models were predominantly based on projection of an El Niño-like warming pattern. Recent studies suggested that a La Niña-like warming pattern is also possible. Here we compare the responses of TC track density (TCTD) over the western North Pacific and North Atlantic to the two distinct global warming patterns. We find that the La Niña-like warming pattern reduces western North Pacific TCTD except in the South China Sea and along China coast and increases NA TCTD, while the El Niño-like ... Read more ...
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Observed emergence of the climate change signal: from the familiar to the unknown - Hawkins - - Geophysical Research Letters - Wiley Online Library - American Geophysical Union (Mar 10, 2020) |
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Mar 10, 2020 · E-mail address: e.hawkins@reading.ac.uk
National Centre for Atmospheric Science, Dept. of Meteorology, University of Reading, UK
Correspondence to: E. Hawkins,
E-mail address: e.hawkins@reading.ac.uk
Environmental Change Institute, University of Oxford, Oxford, UK
School of Earth Sciences and ARC Centre of Excellence for Climate Extremes, University of Melbourne, Australia
National Centre for Atmospheric Science, Dept. of Meteorology, University of Reading, UK
E-mail address: e.hawkins@reading.ac.uk
National Centre for Atmospheric Science, Dept. of Meteorology, University of Reading, UK
Correspondence to: E. Hawkins,
E-mail ... Read more ...
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Urban renewal can mitigate urban heat islands - American Geophysical Union (Mar 10, 2020) |
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Mar 10, 2020 · How can urban renewal effectively contribute to urban climate? Shanghai, one of the world's first metropolises to utilize effective urban heat island (UHI) mitigation strategies, is investigated by analyzing meteorological and land use observations over the past 144 years. The UHI decreased by ~0.58 °C between 2005 and 2016 due to urban renewal characterized by an increase in vegetation cover and the closure of the high-energy consumption industries in urban areas. Simulation results also indicate that future mitigation strategies should strive to increase vegetation cover, as a 10–20% increase in vegetation cover is anticipated to reduce the UHI by 0.38–0.78 °C, resulting in ... Read more ...
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Long-term impacts of permafrost thaw on carbon storage in peatlands: deep losses offset by surficial accumulation - American Geophysical Union (Feb 19, 2020) |
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Feb 19, 2020 · E-mail address: wheffern@ualberta.ca
Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada
Correspondence to: L. Heffernan,
E-mail address: wheffern@ualberta.ca
Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada
Institute for Landscape Ecology, Ecohydrology and Biogeochemistry Group, University of Münster, Münster, Germany
Institute for Landscape Ecology, Ecohydrology and Biogeochemistry Group, University of Münster, Münster, Germany
Department of Geography, Université de Montréal, Montreal, QC, Canada
Department of Renewable Resources, University of Alberta, Edmonton, AB, ... | By Liam Heffernan Read more ...
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The environmental footprint of transport by car using renewable energy - American Geophysical Union (Jan 31, 2020) |
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Jan 31, 2020 · Replacing fossil fuels in the transport sector by renewable energy will help combat climate change. However, lowering greenhouse gas emissions by switching to alternative fuels or electricity can come at the expense of land and water resources. To understand the scale of this possible tradeoff we compare and contrast carbon, land and water footprints per driven km in midsize cars utilizing conventional gasoline, biofuels, bioelectricity, solar electricity and solar-based hydrogen. Results show that solar-powered electric cars have the smallest environmental footprints per km, followed by solar-based hydrogen cars, and that biofuel-driven cars have the largest ... | By Bunyod Holmatov Read more ...
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