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 re–enrich 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.
Dry deposition of particles to canopies—A look back and the road forward
in JGR: Atmospheres
Comparison of the nontransport processes that affect PM
concentration in the
lowest 100 m of the atmosphere as estimated from a regional-scale air quality model simulation for June 2013. The area over which the results
(averages) apply is about 500 km × 500 km, as indicated by the inner square of the CAMx domain illustration inset. The time scale markings indicate
noon (EST). The dry deposition estimates result from an assumption about the deposition velocity that is a focus of the current presentation. The time
period selected for this illustration was free of rainfall.
Modeled Chl:C ratio and derived estimates of phytoplankton carbon biomass and its contribution to total particulate organic carbon in the global surface ocean
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.
Dynamics of primary productivity in the northern South China Sea over the past 24,000 years
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 Pacic. (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.
Earth and Space Science
in Earth and Space Science
Earth and Space Science is the only journal that reflects
the expansive range of science represented by AGU’s 62,000 members,
including all of the Earth, planetary, and space sciences, and related
fields in environmental science, geoengineering, space engineering,
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.
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.
Panel regressions to estimate low-flow response to rainfall variability in ungaged basins
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 Q70k¯ associated with rainfall A computed using rainfall elasticity ( εx) values from random-effects panel regressions for ungaged basins and from streamflow records for gaging stations. (d) Percentage changes in Q70k¯ associated with rainfall B computed using εx 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.
Spatially and temporally systematic hydrologic changes within large geoengineered landslides, Cromwell Gorge, New Zealand, induced by multiple regional earthquakes
in JGR: Solid Earth
map of landslides in the Cromwell Gorge, central Otago, South Island of New Zealand with an inset
showing the location with respect to the rest of New Zealand. Map coordinates shown are in meters NZTM2000. The location of instruments recording
hydrological data and the nature of the identified earthquake-induced responses are also shown: monitoring wells by grey circles, tunnel V notch weirs by
squares, and tunnel flow buckets by grey diamonds; red markers (arrows, squares, and diamonds) indicate positive responses and orange markers indicate
negative responses. The markers are scaled to reflect the approximate amplitude of change. Drainage tunnels, not specifically shown, can be located and
visualized by the consecutive alignment of the tunnel flow bucket symbols. Landslides specifically referred to in the text have been labeled: BRE–Brewery
Creek; NMU–Nine Mile Upstream; NMD–Nine Mile Downstream; NO5–Number 5; JAC–Jacksons; and CLY–Clyde.
in Earth's Future
A transdisciplinary, open-access science journal,
Earth’s Future examines the state of the planet and its inhabitants, and
the predictions of its future. The journal assesses the challenges and
opportunities associated with regional and global change in an era
where humans dominate Earth’s environment, resources and ecosys-
tems. It publishes peer-reviewed articles, re views and (short and long-
form) commentaries in areas that include water, air, food, energy, haz-
ards, climate, ecosystems, human health and demographics, among
others. Contributions focus on Earth as an interconnected, evolving sys-
tem to inform researchers, policy makers and the public on the science
of the Anthropocene.
Fault-bound valley associated with the Rembrandt basin on Mercury
Mercury’s great valley revealed in a 3D perspective view using a high-resolution digital elevation model derived from stereo images obtained by NASA’s MESSENGER spacecraft. Below the perspective view is a high-incidence angle image mosaic of the region. Mercury’s 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.
A model for stealth coronal mass ejections
in JGR: Space Physics
(left) STA-COR1 observation with representative PFSS field lines overplotted showing the faint white-light signature of the eruption X point [adapted from Lynch et al., 2010]. (right) Synthetic white-light ratio image at t = 174 h from ϕSTA perspective showing the stealth CME simulation X point structure.