ALBERT

Description: The extended multi-linear regression (eMLR) method is used to determine the uptake and storage of anthropogenic carbon in the Atlantic Ocean based on repeat occupations of 4 cruises from 1989–2014 (A16, A20, A22, and A10), with an emphasis on the 2003–2014 period. The results show a significant increase in basin wide anthropogenic carbon storage in the North Atlantic, which absorbed 4.4 ± 0.9 Pg C decade -1 from 2003–2014 compared to 1.9 ± 0.4 Pg C decade -1 for the 1989–2003 period. This decadal variability is attributed to changing ventilation patterns associated with the North Atlantic Oscillation (NAO) and increasing release of anthropogenic carbon into the atmosphere. There are small changes in the uptake rate of CO 2 in the South Atlantic for these time periods (3.7 ± 0.8 Pg C decade -1 versus 3.2 ± 0.7 Pg C decade -1 ). Several eddies are identified containing ~20% more anthropogenic carbon than the surrounding waters in the South Atlantic demonstrating the importance of eddies in transporting anthropogenic carbon. The uptake of carbon results in a decrease in pH of ~0.0021 ± 0.0007 yr -1 for surface waters during the last 10 years, in line with the atmospheric increase in CO 2 .

Description: This study compared summer stream temperature between two years in the Star Creek catchment, Alberta, a headwater basin on the eastern slopes of the Canadian Rocky Mountains. Star Creek is a subsurface water dominated stream, which represents important habitat for native salmonid species. Hydro-meteorological data from May-September of 2010 and 2011 accompanied by stream energy budget calculations were used to describe the drivers of stream temperature in this small forested stream. Mean, maximum and minimum weekly stream temperatures were lower from May to August and higher in September 2011 compared to 2010. Weekly range in stream temperature was also different between years with a higher range in 2010. Inter-annual stream temperature variation was attributed discharge differences between years, shown to be primarily governed by catchment-scale moisture conditions. This study demonstrates that both meteorological and hydrological processes must be considered in order to understand stream temperature response to changing environmental conditions in mountainous regions. Copyright © 2013 John Wiley & Sons, Ltd.

Description: Ecological, sedimentological, and sediment transport data were analysed to understand the interconnections between coastal morphology and reef ecology within a fringing reef system. The sediment reservoir is predominantly derived from ‘old’ source material (≥ 1400 years old) but this material is supplied to the shoreline on modern timescales. These results suggest that sediment budgets of similar reef systems may be more resilient to climate change as contemporary reef health and community composition have limited influence on sediment supply. Abstract Reef‐associated landforms are coupled to the health of the reef ecosystem which produces the sediment that forms and maintains these landforms. However, this connection can make reef‐fronted coastlines sensitive to the impacts of climate change, given that any decline in ecosystem health (e.g. decreasing sediment supply) or changes to physical processes (e.g. sea level rise, increasing wave energy) could drive the sediment budgets of these systems into a net erosive state. Therefore, knowledge of both the sediment sources and transport mechanisms is required to predict the sensitivity of reef‐associated landforms to future climate change. Here, we examine the benthic habitat composition, sediment characteristics (composition, texture, and age), and transport mechanisms and pathways to understand the interconnections between coastal morphology and the reef system at Tantabiddi, Ningaloo Reef, Western Australia. Benthic surveys and sediment composition analysis revealed that although live coral accounts for less than 5% of the benthic cover, coral is the dominant sediment constituent (34% on average). Sediment ages (238U/230Th) were mostly found to be thousands of years old, suggesting that the primary sediment source is relic reef material (e.g. Holocene reef framework). Sediment transport across the lagoon was quantified through measurements of ripple migration rates, which were found to be shoreward migrating and responsible for feeding the large shoreline salient in the lee of the reef. The derived sediment fluxes were comparable with previously measured rates of sediment production by bioerosion. These results suggest that sediment budgets of systems dependent on old (〉103 years) source materials may be more resilient to climate change as present‐day reef health and community composition (i.e. sources of ‘new’ carbonate production) have limited influence on sediment supply. Therefore, the vulnerability of reef‐associated landforms in these systems will be dictated by future changes to mechanisms of sediment generation (e.g. bioerosion) and/or physical processes. © 2018 John Wiley & Sons, Ltd.

Description: In the western U.S., shifts from snow to rain precipitation regimes and increases in western juniper cover in shrub-dominated landscapes can alter surface water input via changes in snowmelt and throughfall. To better understand how shifts in both precipitation and semi-arid vegetation cover alter above-ground hydrological processes, we assessed: how rain interception differs from and snow and rain surface water input; how western juniper alters snowpack dynamics; and how these above-ground processes differ across western juniper, mountain big sagebrush, and low sagebrush plant communities. We collected continuous surface water input with four large lysimeters, interspace and below-canopy snow depth data, and conducted periodic snow surveys for two consecutive water years (2013 and 2014). The ratio of interspace to below canopy surface water input was greater for snow relative to rain events, averaging 79.4% and 54.8% respectively. The greater surface water input ratio for snow is in part due to increased deposition of redistributed snow under the canopy. We simulated above-ground energy and water fluxes in western juniper, low sagebrush, and mountain big sagebrush for two eight-year periods under current and projected mid-21 st century warmer temperatures with the Simultaneous Heat and Water model. Juniper compared to low and mountain sagebrush reduced surface water input by an average of 138 mm or 24% of the total site water budget. Conversely, warming temperatures reduced surface water input by only an average of 14 mm across the three vegetation types. The future (warmer) simulations resulted in earlier snow disappearance and surface water input by 51 and 45 days, respectively, across juniper, low sagebrush, and mountain sagebrush. Information from this study can help land managers in the sagebrush steppe understand how both shifts in climate and semi-arid vegetation will alter fundamental hydrological processes. This article is protected by copyright. All rights reserved.

Description: Remote Sensing, Vol. 10, Pages 991: Investigations into Frost Flower Physical Characteristics and the C-Band Scattering Response Remote Sensing doi: 10.3390/rs10070991 Authors: Dustin Isleifson Ryan J. Galley Nariman Firoozy Jack C. Landy David G. Barber A dedicated study on the physical characteristics and C-band scattering response of frost-flower-covered sea ice was performed in an artificial sea ice mesocosm over a 36-h period in January 2017. Meteorological conditions were observed and recorded automatically at the facility when the sea ice grew and frost flowers formed while the C-band scattering measurements were conducted continuously over a range of incidence angles. Surface roughness was characterized using a LiDAR. During the experiment, frost flowers did not initially form on the extremely smooth ice surface even though suitable meteorological conditions prevailed during their development (low air temperature, low near-surface wind speed, and high near-surface relative humidity). This provides evidence that both the presence of (i) liquid brine at the surface and (ii) raised nodules as nucleation points are required to enable frost flower initiation. As the ice thickened, we observed that raised nodules gradually appeared, frost flowers formed, and flowers subsequently spread to cover the surface over a six-hour period. In contrast to previous experiments, the frost flower layer did not become visibly saturated with liquid brine. The C-band scattering measurements exhibited increases as high as 14.8 dB (vertical polarization) in response to the frost flower formation with low incidence angles (i.e., 25°) showing the largest dynamic range. Co-polarization ratios responded to the physical and thermodynamic changes associated with the frost flower formation process. Our results indicate that brine expulsion at the sea ice surface and frost flower salination can have substantial temporal variability, which can be detected by scatterometer time-series measurements. This work contributes towards the operational satellite image interpretation for Arctic waters by improving our understanding of the highly variable C-band microwave scattering properties of young sea ice types.

Description: The ecohydrological separation hypothesis states that transpiration through plants and drainage to streams and groundwater are sourced from separate soil water pools, which possess distinct isotopic signatures. Evidence for ecohydrological separation has relied on the globally ubiquitous observation that plant water and draining water are isotopically distinct. We evaluated the ecohydrological separation hypothesis in the Dry Creek Experimental Watershed in the semiarid, snow-dominated landscape of southwest Idaho, USA. We found that plant water is indeed isotopically distinct from streams and groundwater. However, we were unable to track those waters to subsurface soil waters, nor were we able to relate soil water mobility to isotopic composition. Soil waters of different mobility can be isotopically similar, and isotopic distinction in soil water can occur for reasons not related to mobility. We suggest that isotopic distinction between root-absorbed and draining waters may not be an appropriate indicator of ecohydrological separation of soil waters, and that hydrologic explanations for such isotopic distinction may not be sufficient.

Description: Since first introduced to North America in 1999, West Nile virus (WNV) has spread rapidly across the continent, threatening wildlife populations and posing serious health risks to humans. While WNV incidence has been linked to environmental factors, particularly temperature and rainfall, little is known about how future climate change may affect the spread of the disease. Using available data on WNV infections in vectors and hosts collected from 2003–2011 and using a suite of 10 species distribution models, weighted according to their predictive performance, we modeled the incidence of WNV under current climate conditions at a continental scale. Models were found to accurately predict spatial patterns of WNV that were then used to examine how future climate may affect the spread of the disease. Predictions were accurate for cases of human WNV infection in the following year (2012), with areas reporting infections having significantly higher probability of presence as predicted by our models. Projected geographic distributions of WNV in North America under future climate for 2050 and 2080 show an expansion of suitable climate for the disease, driven by warmer temperatures and lower annual precipitation that will result in the exposure of new and naïve host populations to the virus with potentially serious consequences. Our risk assessment identifies current and future hotspots of West Nile virus where mitigation efforts should be focused and presents an important new approach for monitoring vector-borne disease under climate change.

Description: The influence of vegetation canopies on the flow structure in streams, rivers and floodplains is heavily dependent on the cumulative drag forces exerted by the vegetation. The drag coefficient of vegetation elements within a canopy has been shown to be significantly different to well-established values for a single element in isolation. This study investigates the mechanisms that determine canopy flow resistance and proposes a new model for predicting canopy drag coefficients. Large Eddy Simulations were used to investigate the fine-scale hydrodynamics within emergent canopies with solid area fractions ( λ ) ranging from 0.016 to 0.25. The influence of three mechanisms in modifying canopy drag, namely blockage, sheltering and delayed separation, were investigated. While the effects of sheltering and delayed separation were found to slightly reduce the drag of very sparse canopies, the blockage effect significantly increased the drag of denser canopies ( λ ≳ 0.04). Furthermore, an analogy drawn between canopy flow and wall-confined flow around bluff bodies is used to propose an alternative reference velocity to the conventional spatially-averaged velocity, namely the constricted cross-section velocity ( U c ), to redefine the canopy drag coefficient. Through comparison with both prior experimental data and the present numerical simulations, typical formulations for the drag coefficient of a single cylinder are shown to accurately predict the drag coefficient of staggered emergent canopies when U c is used as the reference velocity. Finally, it is shown that this new model can be extended to predict the bulk drag coefficient of randomly-arranged vegetation canopies. This article is protected by copyright. All rights reserved.

Description: Ephemeral wetlands in arid regions are often degraded or destroyed through poor land-use practice long before they are ever studied or prioritized for conservation. Climate change will likely also have implications for these ecosystems given forecast changes in rainfall patterns in many arid environments. Here, we present a conceptual diagram showing typical and modified ephemeral wetlands in agricultural landscapes and how modification impacts on species diversity and composition.