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.

Development and evaluation of a physics-based windblown dust emission scheme implemented in the CMAQ modeling system in JAMES

In Forouta et al., the emission of particulate matter with diameter less than 10 microns (PM10) due to dust outbreaks over the southwestern United States in March 7, 2011 (top left), March 21, 2011 (top right), April 3, 2011 (bottom left), and May 29, 2011 (bottom right). The results (in gm-3) are obtained using a newly developed windblown dust scheme implemented in the Community Multiscale Air Quality (CMAQ) modeling system

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.

Seasonal hyporheic dynamics control coupled microbiology and geochemistry in Colorado River sediments in JGR: Biogeosciences

image shows (a) Map of hydraulic head in the floodplain aquifer across three sampling seasons.

Samples for this study were collected at the location marked by a white circle. The black dots indicate groundwater monitoring well locations used for
hydrologic calculations. (b) River stage hydrograph for the Colorado River with sampling times indicated by blue lines. (c) Magnitude (black line) and
direction (red arrows) of Darcy flux through the floodplain aquifer near the sampling location based upon local hydraulic head calculations. Groundwater
flow is generally south toward the river.

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.

Fidelity of the Sr/Ca proxy in recording ocean temperature in the western Atlantic coral Siderastrea siderea in G-Cubed

In Kufner et al. [DOI: 10.1002/2016GC006640], image shows an example of one of the 39 Siderastrea siderea colonies included in this study (a) attached

to a calcication monitoring block with a temperature logger (black, on left) on the Fowey Rocks reef crest, and (b) slabbed in half showing Alizarin Red-S stain
lines (pink) marking 29 April 2011 (lower line) and 9 May 2012 (upper line). The upper surface of the slab marks the collection date of 16 May 2013. Scale bar
on left of Figure 1b is a cm ruler with mm markings. (c) Inset box from Figure 1b with annual cycle of Sr/Ca in two replicate drill-paths (blue and green lines)
between the stain lines. Y axis is reversed so that Sr/Ca values (mmol mol
–1
) indicating warmer values are up. X axis is time (decimal years).

Tidal flow separation at protruding beach nourishments in JGR: Oceans

Radermach et al. [DOI: 10.1002/2016JC011942] observed tidal ow separation o the Sand Motor, a mega-scale beach nourishment at the Dutch

coastline. Field measurements and model simulations show that the presence and characteristics of the generated eddies (visible in the suspended matter
concentration in the left picture) depend on a combination of the shape of the coastline perturbation, tidal excursion length and bottom friction. As a result
the eddy intensities at these coastal protection works vary with the spring-neap tidal cycle and their large-scale morphological evolution.

Atmospheric escape from unmagnetized bodies in JGR: Planets

 Venus, Mars, Titan, Pluto, and a comet are shown at the same scale to illustrate the relative sizes of the

interaction region (blue) produced by a flowing plasma—the solar wind (light green) in all cases but Titan that is sitting in the magnetosphere (red)—
impinging on the planetary exosphere (orange). The supersonic solar wind is slowed and compressed behind an upstream bow shock with the plasma
deflected around the obstacle in a sheath flow (dark green).

A miniature, low-power scientific fluxgate magnetometer: A stepping-stone to cube-satellite constellation missions in JGR: Space Physics

The Ex-Alta 1 Cube-Satellite, to be launched in late 2016 as part of the ESA QB50 constellation mission, will demonstrate the potential

for scientifically valuable magnetic field measurements from a Cube-Satellite. For more information on the magnetometer, boom, and satellite

Relationship between the direction of diurnal rainfall migration and the ambient wind over the Southern Sumatra Island in Earth and Space Science

In Yanase et al., image shows time-longitude cross sections of the composite surface rain rate from TRMM 2A25 for (a) December, January, and February; (b) March, April, and May; (c) June, July, and August; and (d) September, October, and November

Postemplacement dynamics of basaltic intrusions in the continental crust in JGR: Solid Earth

In Roman and Jaupart [10.1002/2016JB013912], the development of downwellings at the leading edge of the intrusion in two different experiments (nos. 1425 and 1427) in the jellyfish regime. The only difference between these two experiments is the intrusion volume, which varies by a factor of 5.6. All the other parameters are identical. This shows that the downwelling dimensions increase with the intrusion volume.

Sorting out compositional trends in sedimentary rocks of the Bradbury group (Aeolis Palus), Gale crater, Mars in JGR: Planets

In Siebach et al. MAHLI image examples of each of the textural classes of rocks in the Bradbury group and (h) the Murray mudstone in the Mount Sharp group. White scale bars are 1 cm across. Classes were divided on the basis of grain size and/or surface texture and coloring and include (Figure 2a) Sheepbed mudstone (10 APXS analyses; example is Wernecke_preDRT, sol 168), exposed in Yellowknife Bay with grains finer than the limit of resolution; (Figure 2b) fine sandstone (15 APXS analyses; example is Aillik1, sol 322), well-sorted siltstones to sandstones; (Figure 2c) sandstone (22 APXS analyses; example is Gillespie_Lake, sol 132), medium to pebbly sandstones; (Figure 2d) conglomerate (15 APXS analyses; example is Bardin_Bluffs, sol 394), primary grain sizes >1 mm, rounded grains, clasts up to 6 cm; (Figure 2e) uncertain (13 APXS analyses; example is Morehouse, sol 503), float rocks with poorly defined grain boundaries, sometimes weather like conglomerates; (Figure 2f) possible igneous (4 APXS analyses; example is Clinton, sol 512), small group of float rocks and one clast in a conglomerate with porphyritic textures, shortened to igneous in plot legends; (Figure 2g) diagenetic (36 APXS analyses; example is CumberlandNewRP_LIBs, sol 277), rocks with clearly diagenetic textures including preferential cementation and fracture fills; and (Figure 2h) Murray mudstone (27 APXS analyses; example is Punchbowl2, sol 813), mudstone observed at

Pahrump Hills in Mount Sharp group, fine grained with potential secondary crystal structures.

The impact of conventional space-time aggregation on the dynamics of continuous-time rainfall in WRR

The south coast of Wellington (NZ), looking east from Baring Head, braces for the arrival of a dramatic cold front that delivered torrential rain and severe southerly gales to the city. Measuring, modelling and understanding the complexity of rainfall states and their temporal and spatial dynamics is at the core of research undertaken
by Sansom et al. (2017). They use a continuous-time rainfall model to better understand how well rainfall dynamics are preserved after aggregation into conventional time periods (minutes, hours, or days) and over different spatial scales. Credit: Katja Riedel, NIWA.

Using large eddy simulations to reveal the size, strength, and phase of updraft and downdraft cores of an Arctic mixed-phase stratocumulus cloud in JGR: Atmospheres

In Roesler et al., total condensate (precipitating rain and snow and nonprecipitating water and ice) and the vertical velocity at 12 h into the simulation for the (left) 1.5 TKE scheme and the (right) CLUBB scheme. The total condensate is shown in the rainbow color bar, and the vertical velocity is shown with the blue-to-red color bar.

in GBC

In Crusius et al., (top left) Expanded map of sampling region. The map at right shows the sampling stations (green circles) on the shelf/slope transect extending seaward from near the mouth of the Copper River (AK) (Station 1) to beyond the shelf break (Station 5).

Surface water currents are denoted with blue arrows and include the Alaska Coastal Current (ACC) along the shelf, the Alaska Current, and Alaskan Stream [modified from Lippiatt et al., 2011]. The thin blue contour line is the 500 m depth contour and gives the approximate position of the shelf break, while the white contour is the 100 m depth contour. Station locations and depth contours are superimposed on a MODIS true-color image from 9 April 2010,
the same day Stations 4 and 5 were sampled. True-color image generated using HDFlook.

The tropical rain belts with an annual cycle and a continent model intercomparison project: TRACMIP in JAMES

annual-mean precipitation response between 40N and 40S to increased CO

2
in aquaplanet and land
simulations. (a) Zonal-mean response in the aquaplanet setup, (b) longitude-latitude response of the model-median precipitation in the land setup, (c) zonal-
mean response in the land setup, and (d) dierence between zonal-mean response in the land versus aquaplanet setup. In Figures 15a, 15c, and 15d models
are colored according to the color coding introduced in Figure 2; the model median is shown by the thick black line. In Figure 15b, the black line is the model-
median ITCZ in LandControl.

Improvements to the snow melting process in a partially double moment microphysics parameterization in JAMES

In Brown et al., idealized squall line experiments using (left column) M20Efrr and (right column) M75Efrr. Top row (a, b) shows surface radar refl ectivity in dBZ, middle row (c, d) shows vertical cross section of line-averaged radar refl ectivity, and bottom row (e, f) shows vertical cross section of line-averaged median drop diameter in mm.

Evolution of submarine eruptive activity during the 2011–2012 El Hierro event as documented by hydroacoustic images and remotely operated vehicle observations in G-Cubed

 Image shows ROV images of the hornitos at the summit of the Tagoro volcano: (a) Location on the images on the multibeam bathymetry from the 28 June 2012. (b) Deepest hornito formed by 4–5 m tall pyramid-like of agglutinated lava blocks intermixed with yellow hydrothermal deposits (115 m water depth). (c) Detail of degassing vents (yellow orifices) along the flanks of the chimney interpreted as active hydrothermal vents (118 m water depth). (d) Top of the shallowest “hornito” (89 m water depth) showing abundance of red flocculates covering the lava deposits. (e) Detail of the flank of a hornito showing white bacterial mats. (f ) Detail the tapestry of red to orange amorphous Fe-oxyhydroxide flocculates covering the overall summit of the Tagoro volcanic edifice.

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., 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.