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.

Air-sea fluxes for Hurricane Patricia (2015): Comparison with supertyphoon Haiyan (2013) and under different ENSO conditions in JGR: Oceans

Hurricane Patricia (Oct., 2015) and Supertyphoon Haiyan (Nov. 2013) are the 2 ‘Champion Tropical Cyclones in the recorded human history. These 2 cyclones can be called category ‘6’ super cyclones, because both reached an astonishing peak intensity, far exceeding the existing highest category of 5 in the tropical cyclone scale. This illustration shows the approach of these 2 super cyclones’ to the Philippines and Mexico, i.e. the 2 sides of the Pacific Ocean. These 2 champion cyclones are compared and reasons are explore on their extra-ordinary intensifications. The tropical cyclone trajectories and intensity are obtained from the best track archives of National Hurricane Centers (NHC; http://ftp.nhc.noaa.gov/atcf/archive/) and the US Joint Typhoon Warning Centre (JTWC; https://metoc.ndbc.noaa.gov/web/guest/jtwc/best_tracks/). The visible images are provided from the Rapid Response imagery from the Land, Atmosphere Near real-time Capability for EOS (LANCE) system operated by the NASA/GSFC/Earth Observing System Data and Information System (EOSDIS)(https://lance.modaps.eosdis.nasa.gov/cgibin/imagery/gallery.cgi). The image of Hurricane Patricia over Mexico was taken from the MODIS instrument aboard NASAs Terra satellite on Oct. 23, 2015 at 17:30 UTC/1:30 p.m. EDT. The image of supertyphoon Haiyan approaching the Philippines was taken from the MODIS instrument aboard NASAs Aqua satellite on Nov. 7, 2013 at 04:25 UTC/Nov. 6 at 11:25 p.m. EDT. Thanks to NASA/EOSDIS (https://lance.modaps.eosdis.nasa.gov/cgi-bin/imagery/gallery.cgi) for providing the visible images from Terra and Aqua/MODIS, and to NHC (http://ftp.nhc.noaa.gov/atcf/archive/), JTWC(https://metoc.ndbc.noaa.gov/web/guest/jtwc/best_tracks/) for TCs best track and intensity data.

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.

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.

Demonstration of a Broadband Very Long Baseline Interferometer System: A New Instrument for High‐Precision Space Geodesy in Radio Science

Radio telescopes distributed around the globe are used to measure the changing shape of the Earth and its orientation in space by observing quasars and galaxies at the edge of the Universe. Out of a desired network size of thirty-two antennas,
the seven indicated are now active. The network, called VGOS, for Very Long Baseline Interferometer Global Observing System, isone component of the
Global Geodetic Observing System, complementing the GNSS (Global Navigation Satellite System), SLR (Satellite Laser Ranging System), and DORIS (Doppler
Orbitography and Radiopositioning Integrated by Satellite) systems. Additional VGOS systems in the USA (Texas), Norway (Svalbard), China, Tasmania, Finland,
South Africa, Canary Islands, and Russia are expected to be operational by 2020.

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.

GPlates: Building a Virtual Earth Through Deep Time in G-Cubed

Mantle temperature deviation windows colored by depth. Coastlines are overlain
with white outlines and semi-transparent continental interiors. (A) Two isosurfaces of cooler downgoing slabs and hotter mantle upwellings without deviation windows. (B) Isosurfaces with deviation windows added. Each constant-temperature main isosurface has its own temperature offset (deviation)Each resultant deviation window has an opaque white isosurface surrounded by two semi-transparent deviation isosurfaces colored by depth. Note the
white isosurfaces are exposed at the surface. (C) Both slab and upwelling deviation windows are limited to the region below the North and South American plates (outlined in black with semi-transparent interior). Note the white isosurfaces are also exposed by the cut-out region. (D) The exposed deviation
windows are  filled in with depth coloring and white isolines. The deviation windows at the outer sphere surface are semi-transparent whereas those along
the side walls are opaque. Note that depth coloring blends from the usual red and blue shades at the deviation isosurfaces to green at the main (white)
isosurfaces.

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°.

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

Hydrothermal nontronite formation associated with microbes from low-temperature diffuse hydrothermal vents at the South Mid-Atlantic Ridge in JGR: Biogeosciences

Ta et al. reported the formation of hydrothermal nontronite associated with microbes from low-temperature diffuse
hydrothermal vents at the South Mid-Atlantic Ridge. NanoSIMS imaging reveals the bacteria cells (red) are surrounded by nontron
ite (green). The
formation of nontronite may begin with the adsorption of cationic iron in the hydrothermal fluid to anionic cellular surfaces.
Biologically induced
mineralization might be widely responsible for the formation of nontronit
e in modern low-temperature hydrothermal environments.

Temporal and Spatial Matching in Human‐Earth System Model Coupling in Earth and Space Science

Image shows grid data for Gross Domestic Product (blue) and population (red) all over China.

Seasonal and interannual variability of the Eastern Tropical Pacific Fresh Pool in JGR: Oceans

Guimbar et al., investigated the eastern tropical fresh pool (EPFP) spatial and temporal dynamics. The maximal surface extension of the EPFP exhibits a very large interannual variability. Over the past decade, two extreme events occurred, clearly related to the El Niño-Southern Oscillation (ENSO) phases with associated anomalies of precipitation, surface currents, and trade wind in the central Pacific. In particular, changes of the atmospheric freshwater fluxes and ocean surface currents during winter 2014 seems to trigger the onset of an abnormal fresh event related to the strong El Niño 2014–2015, leading to these unprecedented maximum values of the EPFP maximum extent (October-November) in 2014 and 2015.

Fault-bound valley associated with the Rembrandt basin on Mercury in GRL

Mercurys great valley revealed in a 3D perspective view using a high-resolution digital elevation model derived from stereo images obtained by NASAs MESSENGER spacecraft. Below the perspective view is a high-incidence angle image mosaic of the region. Mercurys great valley is over 1,000 km long, extends into the Rembrandt basin, and is bound on one side by Enterprise Rupes, the largest fault scarp on Mercury. The vertical exaggeration is 20X. See also Watters et al., doi: 10.1002/2016GL070205. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/German Aerospace Center–DLR/Smithsonian Institution.

Historic and projected changes in vapor pressure deficit suggest a continental-scale drying of the United States atmosphere in JGR: Atmospheres

In Ficklin and Novick [DOI: 10.1002/2016JD025855], trends of vapor pressure deficit (VPD), saturation vapor pressure (es) and actual vapor

pressure (ea) from 1979 to 2013 for all seasons. The hatched regions represent a significant trend at p < 0.05.

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

 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].

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.

Dynamics of primary productivity in the northern South China Sea over the past 24,000 years in G-Cubed

Conceptual model of the paleoceanographic changes related to the dynamics of PP in the northern SCS.

The light and dark-blue segments represent low-nutrient water and high-nutrient water, respectively. The white arrows represent wind-driven water mixing,
which was weaker in the Holocene and stronger during the deglaciation and LGM. ‘KI’ means Kuroshio Intrusion into the SCS and ‘KC’ means the Kuroshio
Current in the western Pacic. (a) During the Holocene non-El Niño years, the Kuroshio only intruded into the northeastern SCS resulting in a shallow nutricline
and a high PP in the northern SCS. (b) In the Holocene El Niño years, the Kuroshio Intrusion into the northern SCS (along with a weakened mixing) led to a deep
nutricline level and a low PP. In the LGM and the last deglaciation, the Kuroshio might have moved eastward (or altogether weakened), variations of EAWM, sea
level, and rainfall control the PP in the northern SCS.

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.

Issue Information in JGR: Space Physics

Sumatra tsunami amplitude map with travel time shown by contours in 30 min time intervals. Bagiya et al., explain ahead-of-tsunami ionospheric disturbances from tsunami-generated acoustic gravity waves.

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.

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).