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.

A PV-approach for dense water formation along fronts: Application to the Northwestern Mediterranean in JGR: Oceans

Giordani et al. [DOI: 10.1002/2016JC012019], intense surface buoyancy losses (–400 W/m2, colour) occurred under the path of Mistral and Tramontane winds (black arrows, N/m2) in the Gulf of Lion (GL) during the ASICS-MED experiment (February 2013). These buoyancy fluxes and positive Ekman pumping (cyan positive, green negative wind-stress curl used as proxy of the Ekman pumping,  N/m3 x 10 5; interval 0.2 x 10–5 N/m3 x 1.105) are key atmospheric conditions for dense water formation (DWF) and preconditioning in the GL. DWF also occurs along the Catalan coast i.e. along the northern branch of the Liguro-Provençal Current where strong horizontal density gradients are present (see brown lines of surface density). DWF results from the coupling between the surface wind stress (black arrows) and lateral buoyancy gradients because this coupling leads to efficient destratification and PV-destruction in frontal regions. As consequence DWF cannot be reduced as a buoyancy flux problem.

Integrating uncertainty propagation in GNSS radio occultation retrieval: From bending angle to dry-air atmospheric profiles in Earth and Space Science

 In Schwarz et al. [DOI: 10.1002/2016EA000234], image shows error correlation matrices from CP and MC methods: (a) Covariance propagated R and (b) Monte Carlo propagated R MC αs for statistically optimized bending angle, (c) propagated R r and (d) Monte Carlo R MC Nr for retrieved refractivity, (e) propagated R pdr and (f) Monte Carlo R MC pdr for retrieved dry pressure, and (g) propagated R Tdr and (h) Monte Carlo R MC Tdr for retrieved dry temperature.

Pacific-Atlantic Ocean influence on wildfires in northeast China (1774 to 2010) in GRL

Fire-scarred Dahurian larch from the Daxing’an Mountains in northeast China.

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.

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

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.

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

Process connectivity in a naturally prograding river delta in WRR

From Figure 15 of Sendrowski and Passalacqua, Process network showing the average connection between variables on the delta. (a) Process network indicating the relationships between variables that have been quantified (solid lines) and relationships with new variables to be measured (dashed lines). (b) Process network of WLD. The solid lines are the time scales of synchronization (white) and information ow (black). Dashed lines indicate the links to be measured among delta variables, such as nitrate and turbidity, at various locations.

40Ar/39Ar geochronology reveals rapid change from plume-assisted to stress-dependent volcanism in the Newer Volcanic Province, SE Australia in G-Cubed

In Oostingh et al., image shows examples of volcanic alignment and geomorphology interpretations. (a) Satellite image of Mt Eccles and (b) interpreted alignment direction. (c) Satellite image of Lake Cartcarrong (maar) and (d) interpreted elongation of the maar structure with preferred orientation.

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).

A decade of volcanic construction and destruction at the summit of NW Rota-1 seamount: 2004–2014 in JGR: Solid Earth

In Schnur et al., eruptive vents observed in 2010. (a) Map showing linear arrangement of vents. (b) Phantom vent. (c) Sulfur vent. (d) Brimstone vent. (e) Styx vent. (f) Charon vent.

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.

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.

Empirical modeling of plasma clouds produced by the Metal Oxide Space Clouds experiment in Radio Science

In Pedersen et al. [DOI: 10.1002/2016RS006079], overview of the experimental observation setup.

Coupled topographic and vegetation patterns in coastal dunes: Remote sensing observations and ecomorphodynamic implications in JGR: Biogeosciences

In Yousefi Lalimi et al.(DOI: 10.1002/2016JG003540), the image shows (a and d) DTM, (b and e) LAI, and (c and f) NDVI for site 1 (Figures 4a–4c) and site 2 (Figures 4d–4f). The first crest-line (closest to the shoreline) and the shoreline are shown in each map.

Stable isotopes in atmospheric water vapor and applications to the hydrologic cycle in Reviews of Geophysics

Galewsky et al. reviews how the isotopic composition of water vapor is impacted by deep convection and how it behaves within

several tropical weather and climate features. a) Deep convection depletes the lower troposphere through convective downdrafts and diffusive exchanges between rain
drops and vapor, and enriches the upper troposphere through condensate detrainment. b) In the context of a monsoon system, deep convection depletes the water
vapor along the monsoon flow, whereas continental recycling acts to reenrich it. c) In the context of the Madden-Julian Oscillation, the lower and middle tropospheric
water vapor is most enriched before the active phase due to the effect of shallow convection. It becomes more depleted during the active phase due to the effect of deep
convection. Finally, it is most depleted after the active phase when the cloud systems are dominated by their stratiform components. d) In tropical cyclones, diffusive
exchanges between rain drops and vapor lead to strongly depleted water vapor in the rain bands, whereas evaporation and sea spray explain the local maximum in the
eye. Galewsky et al reviews the implications of these properties to better understand convective processes and more generally the hydrological cycle.

Four-dimensional imaging of moisture dynamics during landslide reactivation in JGR: Earth Surface

In Uhlemann et al. [DOI: 10.1002/2016JF003983], image shows change in GMC from baseline model (Figure 7). Red colors indicate a relative

drying, while blue colors indicate wetting; opaque subvolumes highlight the areas where moisture contents change by more than ±10%. The years
2010 and 2011 show the typical seasonal characteristics: surficial wetting following prolonged winter rainfall (November–March) and surficial drying
during the summer months (May–September). Deeper wetting fronts at the base of the slope are indicative of regional groundwater dynamics, while
an area of surficial wetting close to the top of the hill coincides with a known location of a sag pond. In contrast, moisture levels in 2012 are generally
higher than imaged in previous years, especially in deeper parts of the back scarp and areas of the WMF. Strongly decreasing moisture contents in
parts of the lobes and back scarp indicate disturbances of the corresponding material, leading to higher crack volume and hence lower bulk GMC. Only
the upper 12 m bgl of the model is shown, corresponding to the depth of the most significant GMC changes.

Estimating refractivity from propagation loss in turbulent media in Radio Science

(a) Surface-based duct refractivity profile and math formulaCn2 profile. (b) Propagation loss (PL) of 1 GHz wave given refractivity and math formulaCn2 profiles in Figure 1a under no turbulence. PL calculated assuming homogeneous turbulence given (c) math formulaCn2=10−15 and (e) 10−14. PL calculated assuming inhomogeneous turbulence given (d) Cs=10−15 and (f) math formulaCn2=10−14.

http://onlinelibrary.wiley.com/doi/10.1002/2016JF004122/abstract in JGR: Earth Surface

In Guillén Ludeña et al. [DOI: 10.1002/2016JF004122], image shows visualization of coherent structures in the mean and instantaneous flow at the initial state. (a) Q isosurface (Q = 1.5) and distribution of the nondimensional bed shear stress in the mean flow, τ/τ 0, where the mean bed shear stress in the upstream part of the main channel is τ  0= 0.0045 ρU2. (b) Qisosurface (Q = 18) in an instantaneous flow field and bathymetry elevation contours. The coherent structures in the instantaneous flow are colored based on the vertical elevation to better describe their position inside the flow domain. The dashed black arrows indicate KH billows advected inside the separated shear layer bordering the recirculation region.

The solid black arrows indicate KH billows advected inside the mixing layer forming at the upstream junction corner. The black dash-dotted line
visualizes the deformed core of a KH billow inside the separated shear layer.

Three-dimensional numerical modeling of thermal regime and slab dehydration beneath Kanto and Tohoku, Japan in JGR: Solid Earth

Two errors were discovered in the originally published version. The units specified in the first footnote of Table A1 have been corrected. In addition, all instances of “(cm^2 s str)^-1” on page 19 have been replaced with “(cm^-2 sr)”. The corrected paper should be considered the version of record.