Current AGU Journal Covers

Current covers of AGU Journals.  For older covers, see the archives of each journal.  High resolution images are available in the issue information PDF of each issue.

Emission factors of health- and climate-relevant pollutants measured in home during a carbon-finance-approved cookstove intervention in rural India in GeoHealth

Photograph of sunlight illuminating smoke from a traditional cookstove in a rural Indian kitchen. See Grieshop et al. [DOI:10.1002/2017GH000066]

to learn more about how particulate matter emissions varied in traditional and alternative cookstoves during a stove replacement intervention in this
village.

Structure and dynamics of a subglacial discharge plume in a Greenlandic fjord in JGR: Oceans

photograph of the JetYak as it approaches the glacier face taken from a helicopter. Inserts

show a picture of the JetYak and of the boat from which it was controlled.

Ceres's obliquity history and its implications for the permanently shadowed regions in GRL

Ceres has plenty of permanently shadowed regions (mapped in blue) at the present day when its obliquity is small. However, due to obliquity changes in the past, only few permanent shadows remain.

Relative linkages of stream water quality and environmental health with the land use and hydrologic drivers in the coastal-urban watersheds of southeast Florida in GeoHealth

The estimated linkages of stream water quality with the land use and hydrologic drivers identify the management targets and priorities to achieve healthy coastal-urban stream ecosystems.

Building the Pamir-Tibetan Plateau—Crustal stacking, extensional collapse, and lateral extrusion in the Central Pamir: 1. Geometry and kinematics in Tectonics

 In Rutte et al. [DOI: 10.1002/2016TC004293], image shows (a–d) Panoramic views of the Muskol dome. Distortion increases toward the image edges. Figures 4a and 4b

are along section A in Figure 8. Thrusts and north vergent, recumbent, isoclinal folds in Figure 4d are in left part of Figure 4c. (e–h) Fault scarps in colluvial and alluvial deposits
and range front normal faults along the active Sarez-Karakul graben system

Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques in JGR: Earth Surface

image shows macrocracks visible within an internal vertical saw-cut face of tuffeau blocks (a) 1,

(b) 3, (c) 4, and (d) 5. Blocks are encased in a layer of fiberglass. Ruler in centimeters.

Interplay between spatially explicit sediment sourcing, hierarchical river-network structure, and in-channel bed material sediment transport and storage dynamics in JGR: Earth Surface

In Czuba et al. image shows Lidar hillshade highlighting major features (river, bluff, and ravine, each with relevant attributes) incorporated into the model. Inset image shows a 64m bluff; note the canoe for scale. Location and extent is shown in Figure3by a small red box.

Panel regressions to estimate low-flow response to rainfall variability in ungaged basins in WRR

Case study of projected changes in rainfall on the Island of Maui, Hawaii, and associated estimates of changes in low flows. (a) Percentage change in average annual rainfall from statistical downscaling models [Timm et al., 2015] at ungaged basins between 1978–2007 and 2071–2099. (b) Percentage change in average annual rainfall from dynamical downscaling models [Zhang et al., 2012; APDRC, 2016] at ungaged basins between 1978–2007 and 2090–2109, Maui Hawaii. (c) Percentage changes in math formulaQ70k¯ associated with rainfall A computed using rainfall elasticity ( math formulaεx) values from random-effects panel regressions for ungaged basins and from streamflow records for gaging stations. (d) Percentage changes in math formulaQ70k¯ associated with rainfall B computed using math formulaεx values from fixed effects panel regressions for ungaged basins and from streamflow records for gaged basins. Basins without an estimate of changes in low flow are classified as nonperennial and streams in these basins do not have natural low flows for recent conditions. Some ungaged streams may be misclassified.

Fire and deforestation dynamics in Amazonia (1973–2014) in GBC

In van Marle et al. [DOI: 10.1002/2016GB005445], Van Marle et al. reconstructed fire dynamics from 1973 to 2014 in the Amazon based

on horizontal visibility records as observed by weather stations distributed over the Bolivian and Brazilian Amazon. This figure shows smoke
from fires observed by the MODIS sensor on board NASAs Aqua satellite during the 2010 fire season, one of the strongest on record. Highest
concentrations of smoke from fires are observed just east of the Andes where smoke from fires farther North and East hits the mountain chain
and is funneled southward. NASA image courtesy: Jeff Schmaltz

Contemporary glacier retreat triggers a rapid landslide response, Great Aletsch Glacier, Switzerland in GRL

Pictured is a measurement campaign in October 2015 using a portable radar interferometer on the Great Aletsch Glacier in Switzerland. The campaign

is part of a long term paraglacial slope stability investigation, aimed at studying the relationship between glacier retreat and rock slope response. The
radar utilizes a rotating fan beam antenna array, in this case, scanning a 170 degree field of view. The continuous series of radar images allow measurement
of deformations taking place on the glacier, and also the Moosfluh rock slope instability, located to the lower right of the photograph.

Increased water yield due to the hemlock woolly adelgid infestation in New England in GRL

Two eddy-covariance flux towers at the Harvard Forest in New England where the hemlock woolly adelgid (Adelges tsugae) infestation has resulted in eastern hemlock (Tsuga canadensis) mortality (photo by David A. Orwig).

Automated detection and characterization of harmonic tremor in continuous seismic data in GRL

A plume of ash and steam plume rises from the summit of Popocatepetl Volcano, Mexico, in July 2014.

Regional to Global Biogenic Isoprene Emission Responses to Changes in Vegetation From 2000 to 2015 in JGR: Atmospheres

The change of annual isoprene emission associated with the change in vegetation coverage from the year of 2000 to 2015

Distribution pattern and mass budget of sedimentary polycyclic aromatic hydrocarbons in shelf areas of the Eastern China Marginal Seas in JGR: Oceans

Wang et al., conducted the first extensive and comprehensive investigation of sedimentary polycyclic aromatic hydrocarbons (PAHs) concentration, flux, and budget in the continental shelves of the Eastern China Marginal Seas (ECMSs). Source apportionment of PAHs indicated significant regional variation, mainly influenced by socioeconomic differences between north and south China. Deposition flux calculation showed that PAHs flux in the ECMSs and its subregions was higher than the North Gulf of Mexico, Mediterranean, and SW Black Sea (Green column), which suggested that the burial effciency of PAHs in the ECMSs was relatively higher than in the other regions considered. The buried capacity for PAHs in the ECMSs was the highest in the world (Red column), which served as an important global sink of PAHs and plays a significant role in the global PAHs cycle.

Holocene history of deep-seated landsliding in the North Fork Stillaguamish River valley from surface roughness analysis, radiocarbon dating, and numerical landscape evolution modeling in JGR: Earth Surface

 In Booth et al., image (a–e) slope maps of the surface evolution of the Oso landslide predicted by a nonlinear model of hillslope sediment flux (equation(1)). Figure6a is 2014 lidar data, while Figures 6b–6e are model results. For comparison, (f) a lidar-derived slope map of the landslide directly southeast of the Oso landslide with a similar size and shape and a predicted age of ~5000 cal years B.P. is presented.

New geochronology constraints on timing and depth of the ancient earthquakes along the Longmen Shan fault belt, eastern Tibet in Tectonics

image shows the occurrences of the pseudotachylytes in the Bajiaomiao village. (a–c) The pseudotachylyte veins present

in the cataclasite with S-C fabrics, (d and e) small injection veins, (f and g) veinlets and network veins, (h and i) foliated breccias with preferred orientation of fractures and
fragments that indicate a thrust sense in the field, and (j–l) drilling sites and pieces of drill cores. Drill holes shown in Figures 3a and 3b are 2.5 cm in diameter and 12 cm in
Figure 3j. Abbreviation: Pst–pseudotachylyte, Cc–cataclasite, Cf–clast fragment.

Continental-scale variation in controls of summer CO2 in United States lakes in JGR: Biogeosciences

In Lapierre et al., based on an analysis of 1080 lakes distributed across the continental U.S., the image shows that surface water CO2 responds to contrasting drivers related to aquatic primary production, respiration by microorganisms, or terrestrial loadings of carbon depending on the climate and landscape context where these lakes are found. These results show that controls on lake CO2

vary geographically, and that
considering that variation will be important for creating accurate global carbon models as well as to understand how changes in climate and terrestrial
landscapes could alter the pathways responsible for the widespread emissions of CO2
by lakes globally.

The role of monsoon-like zonally asymmetric heating in interhemispheric transport in JGR: Atmospheres

In Chen et al. [DOI: 10.1002/2016JD026427], figure 1 shows schematic summary of the two mechanisms of interhemispheric transport:

(a) the boreal winter Hadley cell (green) transporting mass across the equator in the lower troposphere and (b) the boreal summer monsoon (red),
characterized by the lower level convergence and upper level divergence, which exchanges mass between the two hemispheres through the upper
tropospheric anticyclone. In Figures 1a and 1b, gray dashed lines indicate the annual mean residual meridional circulation, and blue lines depict
isentropic surfaces and eddy mixing.

Global ULF waves generated by a hot flow anomaly in GRL

A hot flow anomaly generates global ULF waves in the magnetosphere. Reflected ions (white arrows) from Earths bow shock are trapped by a tangential discontinuity (purple dashed line) and drift along it, interact with the incident solar wind ions and form a hot plasma region (yellow region) called Hot Flow Anomaly (HFA). The hot plasma region expands and form shocks (blue arrows) on two sides of the structure. In this study, an HFA was observed by Cluster 1 spacecraft, generating ULF waves in the magnetosphere globally (the red dashed lines represent the undisturbed magnetic field lines, the red solid lines represent the magnetic field lines with ULF waves).

Oceanic nitrogen cycling and N2O flux perturbations in the Anthropocene in GBC

Schematic of the biogeochemical feedbacks and their sign of change associated with warming and increased N deposition. Solid lines represent direct effects, light-colored lines represent indirect effects. Thickness of the lines represent, in a semiquantitative way, the intensity of the perturbation. Warming directly enhances metabolic rates (net primary production (NPP), N2 fixation (N2 fix), and remineralization) and stratification and reduces O2 solubility and meridional overturning circulation (MOC). Intensified stratification reduces ocean ventilation driving additional O2 decline and limits the supply of new nutrients in the euphotic zone. This contrasts the enhanced surface nutrient availability due to faster remineralization and the higher growth rates, resulting in little net change of NPP and N2 fix. Reduced new nutrient inputs lead to a decline in export production (EP), which in turn reduce benthic denitrification (BD) and O2 consumption at depth. However, the combination of the warming-driven processes results in a net O2 reduction, which intensifies water column denitrification (WCD). More N loss via WCD compensated by less N loss via BD and small changes in N2 fix result in little net N inventory change. N2O production decline due to reduced EP is larger than the N2O production increase in low-O2 waters. This, together with stratification-reduced N2O outgassing, circulation slowdown, and human-driven atmospheric N2O increase (N2O anthro) contribute to reduce oceanic N2O emissions (N2O emissions). Nitrogen deposition stimulates NPP but reduces the niche of N2 fixers with a small EP increase. This, in turn, stimulates BD and O2 demand at depth that result in larger WCD. Overall, the atmospheric N inputs are compensated by more N loss via denitrification and reduced N2 fix, with little net effect on N2O production and oceanic emissions. For the combined perturbations, the net sign of change of each process is given by the sum of the signs scaled by the line thickness.