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.

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.

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

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.

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.

Decoupling of coral skeletal δ13C and solar irradiance over the past millennium caused by the oceanic Suess effect in Paleoceanography

In Deng et al., satellite image of Hainan Island and the northern SCS. Yellow stars indicate sampling locations.

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.

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.

Wet atmospheric deposition of organic carbon: An underreported source of carbon to watersheds in the northeastern United States in JGR: Atmospheres

In Iavorivska et al. [DOI: 10.1002/2016JD026027], spatial distribution of annual wet atmospheric DOC deposition across Pennsylvania in 2012.

The climatic significance of Late Ordovician-early Silurian black shales in Paleoceanography

 In Pohl et al., analysis of the patterns of marine primary productivity and oxygen concentration simulated using the 440 Ma land-sea mask and a solar forcing level of 350 W m−2. (a) Surface primary productivity. White and red dots respectively stand for sediments of Katian age associated with dysoxic-to-oxic and at least intermittently anoxic conditions (i.e., black shales, including interbedded black shales), after

the compilation of Melchin et al. [2013]. (b) Contribution of surface phosphate concentration to the primary productivity (third term in equation (1)).
(c) Contribution of the PAR to the surface primary productivity (second term in equation (1)). (d) Vertical velocity averaged over the first 50 m of the water column. Positive values correspond to upwelling water masses. (e) Oxygen concentration simulated at the depth of the epicontinental seas in
the model (80 m), with Katian data points from Melchin et al. [2013].

Detection of diffuse seafloor venting using a structured light laser sensor: 1. Development of a classification based detection method in Earth and Space Science

In Smart et al., image shows results of the updated classification algorithm at Shrimp Vent with the main area of sampling indicated by the dashed white circle. (a) 2D photomosaic of the Shrimp Vent area showing the distribution of bacterial mats and seafloor characteristics. (b) Gridded results of the SVM classification method showing seafloor (blue), bacteria (green) and active venting (yellow). (c)Classification algorithm results showing only areas of active venting in red indicating the spatial distribution of active venting.

Improving representation of canopy temperatures for modeling subcanopy incoming longwave radiation to the snow surface in JGR: Atmospheres

(a) Optical image of 360° canopy edge around the large gap and associated thermal images on

(b) a clear-sky day 20 April 2016 at 13:00 and (c) a cloudy day 30 March 2016 at 10:00. T
1
and T
2
indicate positions of trees installed with thermocouples
(Tree 1 and Tree 2, respectively). T
b
and T
b
indicate reference air temperature during imaging of thermal images in Figures
3
a and
3
b.

Ultrafine particle number fluxes over and in a deciduous forest in JGR: Atmospheres

Pryor et al. [DOI: 10.1002/2016JD025854] computed fluxes of ultra-fine particles (UFP) above and below the canopy of a mature deciduous

forest during leaf-on and leaf-off periods (using the multi-level sampling design shown). The results indicate that despite a comparatively high
frequency of upward ultra-fine particle number fluxes, the forest is a net sink for UFP. Further, the majority of UFP that are deposited to the forest are
removed by the over-story even during leaf-off. Understanding the flux partitioning between the over-story and ground and the uptake of UFP by
forests is essential to improving the representation of atmospheric aerosol particles in Earth System Models.

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.

Carbon isotope offsets between benthic foraminifer species of the genus Cibicides (Cibicidoides) in the glacial sub-Antarctic Atlantic in Paleoceanography

benthic foraminifer accumulation rates during Termination I in core MD07‐3076Q. (a) Accumulation

rate of C. kullenbergi in grey, C. cf. wuellerstorfi in red, and C. wuellerstorfi in orange (the grey shaded area indicates the detection limit of the analyses,
i.e., one foraminifer per gram dry bulk sediment times the linear sedimentation rate times the dry bulk sediment density of the 8cm
3
samples). (b) The
δ
13
C of C. wuellerstorfi (orange), C. cf. wuellerstorfi (red), and C. kullenbergi (grey) with the global benthic δ
18
O stack (and its standard error) of Lisiecki
and Raymo [2005] for reference in light grey.

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.

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.

Photon Pressure Force on Space Debris TOPEX/Poseidon Measured by Satellite Laser Ranging in Earth and Space Science

The orientation circles in the orbital coordinate system calculated for 132 amplitudes A measured during the 3 day period (26–29 October 2015). The intersection of the circles indicates the satellite spin axis orientation (az
imuth = 18.7°, elevation = −7.8°);
the position of the orbital perigee is at azimuth = 0°, elevation = 0°.

Modeled Chl:C ratio and derived estimates of phytoplankton carbon biomass and its contribution to total particulate organic carbon in the global surface ocean in GBC

Arteaga et al. calculated the carbon biomass of marine algae (phytoplankton) in

the surface ocean and their relative contribution to the total particulate organic carbon pool. Phytoplankton constitutes a higher portion
of particulate organic carbon in regions associated with low primary productivity, and vice versa. These findings are based on satellite
information of ocean chlorophyll and a physiological model that describes the internal regulation of energy and resources by the cells (a & b).
(c) Light and nutrients are key in determining phytoplankton growth, and their co-limiting effects are expressed in the regulation of the cells’
Chlorophyll:Carbon ratio via photoacclimation.

CO2 flux from Javanese mud volcanism in JGR: Solid Earth

In Queißer et al. [10.1002/2017JB013968], snapshots of a bursting gas bubble of the main vent (vent II) at the Bledug Kuwu complex. The bursts had a duration of approximately ~2s.