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Journal articleNicholls JF, Toumi R, Stenchikov G, 2014,
Effects of unsteady mountain-gap winds on eddies in the Red Sea
, Atmospheric Science Letters, Vol: 16, Pages: 279-284, ISSN: 1530-261X -
Conference paperWilson DJ, van de Flierdt T, Bridgestock LJ, et al., 2014,
Radiogenic isotopes as paleoceanographic tracers in deep-sea corals: advances in TIMS measurements of Pb isotopes and application to Southern Ocean corals
, American Geophysical Union Fall Meeting 2014 -
Journal articleMistry R, Eastwood JP, Hietala H, 2014,
Detection of small-scale folds at a solar wind reconnection exhaust
, Journal of Geophysical Research: Space Physics, Vol: 120, Pages: 30-42, ISSN: 2169-9402Observations of reconnection in the solar wind over the last few years appear to indicate that the majority of large-scale reconnecting current sheets are roughly planar, and that reconnection itself is quasi-steady. Most studies of solar wind exhausts have used spacecraft with large separations and relatively low time cadence ion measurements. Here we present multipoint Cluster observations of a reconnection exhaust and the associated current sheet at ACE and Wind, enabling it to be studied on multiple length scales and at high time resolution. While analysis shows that on large scales the current sheet is planar, detailed measurements using the four closely spaced Cluster spacecraft show that the trailing edge of the reconnection jet is nonplanar with folds orthogonal to the reconnection plane, with length scales of approximately 230 ion inertial lengths. Our findings thus suggest that while solar wind current sheets undergoing reconnection may be planar on large scales, they may also exhibit complex smaller-scale structure. Such structure is difficult to observe and has rarely been detected because exhausts are rapidly convected past the spacecraft in a single cut; there is therefore a limited set of spacecraft trajectories through the exhaust which would allow the nonplanar features to be intercepted. We consider how such nonplanar reconnection current sheets can form and the processes which may have generated the 3-D structure that was observed.
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Journal articleArcher MO, Turner DL, Eastwood JP, et al., 2014,
Global impacts of a Foreshock Bubble: Magnetosheath, magnetopause and ground-based observations
, Planetary and Space Science, Vol: 106, Pages: 56-66, ISSN: 1873-5088Using multipoint observations we show, for the first time, that Foreshock Bubbles (FBs) have a global impact on Earth׳s magnetosphere. We show that an FB, a transient kinetic phenomenon due to the interaction of backstreaming suprathermal ions with a discontinuity, modifies the total pressure upstream of the bow shock showing a decrease within the FB׳s core and sheath regions. Magnetosheath plasma is accelerated towards the intersection of the FB׳s current sheet with the bow shock resulting in fast, sunward, flows as well as outward motion of the magnetopause. Ground-based magnetometers also show signatures of this magnetopause motion simultaneously across at least 7 h of magnetic local time, corresponding to a distance of 21.5RE transverse to the Sun–Earth line along the magnetopause. These observed global impacts of the FB are in agreement with previous simulations and in stark contrast to the known localised, smaller scale effects of Hot Flow Anomalies (HFAs).
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Journal articleStephenson SN, Roberts GG, Hoggard MJ, et al., 2014,
A Cenozoic Uplift History of Mexico and its Surroundings From Longitudinal River Profiles
, Geochemistry, Geophysics, Geosystems, Vol: 15, Pages: 4734-4758, ISSN: 1525-2027Geodynamic models of mantle convection predict that Mexico and western North America share a history of dynamic support. We calculate admittance between gravity and topography, which indicates that the elastic thickness of the plate in Mexico is 11 km and in western North America it is 12 km. Admittance at wavelengths > 500 km in these regions suggests that topography is partly supported by subcrustal processes. These results corroborate estimates of residual topography from isostatic calculations and suggest that the amount of North American topography supported by the mantle may exceed 1 km. The Cenozoic history of magmatism, sedimentary flux, thermochronometric denudation estimates, and uplifted marine terraces imply that North American lithosphere was uplifted and eroded during the last 30 Ma. We jointly invert 533 Mexican and North American longitudinal river profiles to reconstruct a continent-scale rock uplift rate history. Uplift rate is permitted to vary in space and time. Erosional parameters are calibrated using incision rate data in southwest Mexico and the Colorado Plateau. Calculated rock uplift rates were 0.15–0.2 mm/yr between 25 and10 Ma. Central Mexico experienced the highest uplift rates. Central and southern Mexico continued to uplift at 0.1 mm/yr until recent times. This uplift history is corroborated by independent constraints. We predict clastic flux to the Gulf of Mexico and compare it to independent estimates. We tentatively suggest that the loop between uplift, erosion, and deposition can be closed here. Mexico's staged uplift history suggests that its dynamic support has changed during the last 30 Ma.
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Journal articleLi G, Harrison SP, Prentice IC, et al., 2014,
Simulation of tree-ring widths with a model for primary production, carbon allocation, and growth
, Biogeosciences, Vol: 11, Pages: 6711-6724, ISSN: 1726-4170We present a simple, generic model of annual tree growth, called "T". This model accepts input from a first-principles light-use efficiency model (the "P" model). The P model provides values for gross primary production (GPP) per unit of absorbed photosynthetically active radiation (PAR). Absorbed PAR is estimated from the current leaf area. GPP is allocated to foliage, transport tissue, and fine-root production and respiration in such a way as to satisfy well-understood dimensional and functional relationships. Our approach thereby integrates two modelling approaches separately developed in the global carbon-cycle and forest-science literature. The T model can represent both ontogenetic effects (the impact of ageing) and the effects of environmental variations and trends (climate and CO2) on growth. Driven by local climate records, the model was applied to simulate ring widths during the period 1958–2006 for multiple trees of Pinus koraiensis from the Changbai Mountains in northeastern China. Each tree was initialised at its actual diameter at the time when local climate records started. The model produces realistic simulations of the interannual variability in ring width for different age cohorts (young, mature, and old). Both the simulations and observations show a significant positive response of tree-ring width to growing-season total photosynthetically active radiation (PAR0) and the ratio of actual to potential evapotranspiration (α), and a significant negative response to mean annual temperature (MAT). The slopes of the simulated and observed relationships with PAR0 and α are similar; the negative response to MAT is underestimated by the model. Comparison of simulations with fixed and changing atmospheric CO2 concentration shows that CO2 fertilisation over the past 50 years is too small to be distinguished in the ring-width data, given ontogenetic trends and interannual variability in climate.
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Journal articlevan de Flierdt T, 2014,
Tina van de Flierdt
, OCEANOGRAPHY, Vol: 27, Pages: 241-241, ISSN: 1042-8275 -
Journal articleWeiss DJ, Atkinson PM, Bhatt S, et al., 2014,
An effective approach for gap-filling continental scale remotely sensed time-series
, ISPRS JOURNAL OF PHOTOGRAMMETRY AND REMOTE SENSING, Vol: 98, Pages: 106-118, ISSN: 0924-2716- Author Web Link
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- Citations: 133
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Journal articleCallaghan AH, Ward B, Vialard J, 2014,
Influence of surface forcing on near-surface and mixing layer turbulence in the tropical Indian Ocean
, DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, Vol: 94, Pages: 107-123, ISSN: 0967-0637 -
Journal articleMcPhillips D, Bierman PR, Rood DH, 2014,
Millennial-scale record of landslides in the Andes consistent with earthquake trigger
, NATURE GEOSCIENCE, Vol: 7, Pages: 925-930, ISSN: 1752-0894- Author Web Link
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- Citations: 41
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