Preprints
There are 6976 Preprints listed.
Old-growth forest loss and secondary forest recovery across Amazonian countries
Published: 2021-06-25
Subjects: Environmental Sciences
There is growing recognition of the potential of large-scale restoration in the Amazon as a “nature-based solution” to climate change. However, our knowledge of forest loss and recovery beyond Brazil is limited, and carbon emissions and accumulation have not been estimated for the whole biome. Combining a 33-year land cover dataset with estimates of above-ground biomass and carbon sequestration [...]
The North Atlantic Warming Hole as Part of a Century-Long Fluctuating Phenomenon
Published: 2021-06-29
Subjects: Physical Sciences and Mathematics
Despite global warming, a region of the North Atlantic has been observed to cool, a phenomenon known as theáNorth Atlantic Warming Holeá(NAWH). The causes of the NAWH remain under debate but its emergence has been linked to a slowdown of the meridional circulation leading to a reduced ocean heat transport into the warming hole region. This note uses previously published evidence to suggest that [...]
Paleoenvironmental change recorded in submarine fans: the Eocene-Oligocene climate transition in the Alpine foreland basin
Published: 2021-06-29
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
The Eocene-Oligocene transition (EOT) was a period of considerable environmental change, signifying the transition from Paleocene greenhouse to Oligocene icehouse conditions. Preservation of the sedimentary signal of such an environmental change is most likely in net-depositional environments, such as submarine fans, which are the terminal parts of sedimentary systems. Here, using sedimentary and [...]
Controls on submarine canyon connection to the shoreline: a numerical modelling approach
Published: 2021-06-29
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics
Submarine canyons with heads located close to shorelines, known as shore-connected canyons, provide a focussed pathway for basinward sediment transport. Placing greater constraints on the key parameters that control the formation of shore-connected canyons can help us predict the efficiency of sediment export to deep-water under different environmental conditions and through time. Using a [...]
C:N:P stoichiometry in six distinct habitats of a glacier terminus in the Yangtze River Source Area
Published: 2021-07-01
Subjects: Biogeochemistry, Earth Sciences, Ecology and Evolutionary Biology, Environmental Sciences, Glaciology, Life Sciences, Other Environmental Sciences, Sustainability
Glaciers are among the least explored environments on Earth, especially from a perspective of nutrient stoichiometry. In this study, we documented and compared the nutrient availabilities (concentrations) and composition (stoichiometric ratios) of nutrients (C, N, and P) in six distinct habitats of a glacier terminus in the Yangtze River Source area, including surface ice (SI), basal ice (BI), [...]
Stereophotogrammetry of clouds observed during T-REX
Published: 2021-06-29
Subjects: Oceanography and Atmospheric Sciences and Meteorology
Stereophotogrammetric images collected during the Terrain-induced Rotor Experiment (T-REX), which took place in Owens Valley, California, in the spring of 2006, were used to track clouds and cloud fragments in space and time. We explore how photogrammetric data complements other instruments deployed during T-REX, and how it supports T-REX objectives to study the structure and dynamics of [...]
Knowing the whole world from the top of a mountain: from orderly systematization to complex explanatory systems
Published: 2021-06-29
Subjects: Earth Sciences, Physical and Environmental Geography, Systems Biology
Fast and fascinating changes in views on nature and systems occurred around 1800, for example in the works of Alexander von Humboldt. While Humboldt rarely used the word system, he searched for the pattern-forming forces of nature by gruesome experiments on animals, including himself, and then drew a map of a mountain that became the basis of biogeography. What did ‘system’ mean then and now, how [...]
Onset of runaway fragmentation of salt marshes
Published: 2021-07-01
Subjects: Earth Sciences, Geomorphology, Hydrology, Sustainability
Salt marshes are valuable but vulnerable coastal ecosystems that adapt to relative sea level rise (RSLR) by accumulating organic matter and inorganic sediment. The natural limit of these processes defines a threshold rate of RSLR beyond which marshes drown, resulting in ponding and conversion to open waters. We develop a simplified formulation for sediment transport across marshes to show that [...]
Multidimensional simulation of PFAS transport and leaching in the vadose zone: impact of surfactant-induced flow and soil heterogeneities
Published: 2021-07-01
Subjects: Environmental Health and Protection, Hydrology, Soil Science
PFAS are emergent contaminants of which fate and transport in the environment remain poorly understood. As surfactants, adsorption at air-water interfaces and solid surfaces in soils complicates the retention and leaching of PFAS in the vadose zone. Recent modeling studies accounting for the PFAS-specific nonlinear adsorption processes predicted that the majority of long-chain PFAS remain in the [...]
Interplay of seismic and a-seismic deformation during the 2020 sequence of Atacama, Chile.
Published: 2021-07-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
An earthquake sequence occurred in the Atacama region of Chile throughout September 2020. The sequence initiated by a mainshock of magnitude Mw6.9, followed 17 hours later by a Mw6.4 aftershock. The sequence lasted several weeks, during which more than a thousand events larger than Ml 1 occurred, including several larger earthquakes of magnitudes between 5.5 and 6.4. Using a dense network that [...]
TEMPERATURE, SALINITY AND OXYGEN CLIMATOLOGY OF AFRICAN CONTINENTAL SHELF WATER, SOUTH OF THE EQUATOR, AND CHANGES SINCE 1945
Published: 2021-07-01
Subjects: Physical Sciences and Mathematics
The first temperature, salinity and oxygen climatologies for waters of the continuous southern African continental shelf is presented. It is based on oceanographic data collected since 1945, sub-sampled at depths of 5, 50 and 100 m on a mixed-spatial grid with 0.25° to 0.5° resolution. The climatologies capture spatial heterogeneities and seasonal variability in key ocean variables for the [...]
Using sedimentological priors to improve 14C calibration of bioturbated sediment archives.
Published: 2021-07-01
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Probability, Statistics and Probability
Radiocarbon (14C) dating is often carried out upon multi-specimen samples sourced from bioturbated sediment archives, such as deep-sea sediment. These samples are inherently heterogeneous in age, but current 14C calibration techniques applied to such age heterogenous samples were originally developed for age homogeneous material. A lack of information about age heterogeneity leads to a systematic [...]
When does faulting-induced subsidence drive distributary network reorganization?
Published: 2021-07-18
Subjects: Earth Sciences, Geomorphology
Deltas exhibit spatially and temporally variable subsidence, including vertical displacement due to movement along fault planes. Faulting-induced subsidence perturbs delta-surface gradients, potentially causing distributary networks to shift sediment dispersal within the landscape. Sediment dispersal restricted to part of the landscape could hinder billion-dollar investments aiming to restore [...]
Subduction earthquakes controlled by incoming plate geometry: The 2020 M>7.5 Shumagin, Alaska, earthquake doublet
Published: 2021-07-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
In 2020, an earthquake doublet, a M7.8 on July 22nd and a M7.6 on October 19th, struck the Alaska-Aleutian subduction zone beneath the Shumagin Islands. This is the first documented earthquake doublet involving a megathrust event and a strike-slip event. The first event partially ruptured a seismic gap, which has not hosted large earthquakes since 1917, and the second event was unusual as it [...]
A CMIP6 ensemble for downscaled monthly climate normals over North America
Published: 2021-07-01
Subjects: Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Use of downscaled global climate model projections is expanding rapidly as climate change vulnerability assessments and adaptation planning become mainstream in many sectors. Many climate change impact analyses use climate model projections downscaled at very high spatial resolution (~1km) but very low temporal resolution (20- to 30-year normals). These applications have model selection [...]