Diagnosing the warming of the Northeastern U.S. Coastal Ocean in 2012 : a linkage between the atmospheric jet stream variability and ocean response

Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 218–227, doi:10.1002/2013JC009393.The temperature in the coastal ocean off the northeastern U.S. during the first half of 2012 was anomalously warm, and this resulted in major impacts on the marine ecosystem and commercial fisheries. Understanding the spatiotemporal characteristics of the warming and its underlying dynamical processes is important for improving ecosystem management. Here, we show that the warming in the first half of 2012 was systematic from the Gulf of Maine to Cape Hatteras. Moreover, the warm anomalies extended through the water column, and the local temperature change of shelf water in the Middle Atlantic Bight was largely balanced by the atmospheric heat flux. The anomalous atmospheric jet stream position induced smaller heat loss from the ocean and caused a much slower cooling rate in late autumn and early winter of 2011–2012. Strong jet stream intraseasonal oscillations in the first half of 2012 systematically increased the warm anomalies over the continental shelf. Despite the importance of advection in prior northeastern U.S. continental shelf interannual temperature anomalies, our analyses show that much of the 2012 warming event was attributed to local warming from the atmosphere.K.C. was supported by the Woods Hole Oceanographic Institution Postdoctoral Scholarship, with funding provided by the Cooperative Institute for North Atlantic Region. G.G.G. was supported by grant N00014-11-1-0160 from the Office of Naval Research. S.J.L. was supported by the National Science Foundation under grant OCE-1154575.2014-07-1

Impact of recently upwelled water on productivity investigated using in situ and incubation-based methods in Monterey Bay

Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 1901–1926, doi:10.1002/2016JC012306.Photosynthetic conversion of inline image to organic carbon and the transport of this carbon from the surface to the deep ocean is an important regulator of atmospheric inline image. To understand the controls on carbon fluxes in a productive region impacted by upwelling, we measured biological productivity via multiple methods during a cruise in Monterey Bay, California. We quantified net community production and gross primary production from measurements of inline image/Ar and inline image triple isotopes ( inline image), respectively. We simultaneously conducted incubations measuring the uptake of 14C, inline image, and inline image, and nitrification, and deployed sediment traps. At the start of the cruise (Phase 1) the carbon cycle was at steady state and the estimated net community production was 35(10) and 35(8) mmol C m−2 d−1 from inline image/Ar and 15N incubations, respectively, a remarkably good agreement. During Phase 1, net primary production was 96(27) mmol C m−2 d−1 from C uptake, and gross primary production was 209(17) mmol C m−2 d−1 from inline image. Later in the cruise (Phase 2), recently upwelled water with higher nutrient concentrations entered the study area, causing 14C and inline image uptake to increase substantially. Continuous inline image/Ar measurements revealed submesoscale variability in water mass structure and likely productivity in Phase 2 that was not evident from the incubations. These data demonstrate that inline image/Ar and inline image incubation-based NCP estimates can give equivalent results in an N-limited, coastal system, when the nonsteady state inline image fluxes are negligible or can be quantified.Funding for this work was provided by NSF awards OCE-1060840 to R.H.R. Stanley, OCE-1129644 to D.P. Nicholson, OCE-1357042 to F.P. Chavez, NASA award NNX14AI06G to M.R. Fewings, the David and Lucile Packard Foundation through their generous annual donation to the Monterey Bay Aquarium Research Institute, an Ocean Ventures Fund award from the WHOI Academic Programs Office to CC Manning, and graduate scholarships from NSERC and CMOS to CC Manning.2017-09-1

An Electroabsorption Study of Porous Silicon

Bulk silicon is an indirect band gap material. When carriers are injected into bulk silicon, electron-hole recombination takes place thermally via phonon exchange, and not by emission of photons. Porous silicon, on the other hand, is a fairly efficient emitter of light in the visible region. Much research is currently under way to find out what makes porous silicon able to emit light. One main theory suggests that the energy bands of bulk silicon may be squeezed by being quantum confined, and porous silicon is just an array of quantum silicon wires. Another possibility is that defects in the huge surface area of porous silicon create additional energy bands. These defect energy bands would allow carrier recombination to take place via photon emission. Porous silicon would be very useful as an optically active material. It is compatible with existing silicon electronics and is not expensive to make. The possibility of having all-silicon electrooptic technology puts porous silicon at the focus of much research

Assessing the Impact of Peat Bog Restoration in Mitigating Carbon Loss by Upland Erosion

Demonstrating the impact of peat bog restoration in mitigating carbon loss by upland erosion requires careful field monitoring. This thesis presents results of a year-long field monitoring project at Flow Moss, a 7 ha area of eroding upland blanket bog in the North Pennines, UK. The aim of the project was to estimate the size of the carbon store at Flow Moss, identify the main drivers and pathways through which peat and carbon were leaving the site, and investigate the effectiveness of restoration methods in reducing peat loss. Three main approaches were used: 1) A subsurface Ground Penetrating Radar (GPR) survey to quantify peat depths. This was coupled with results from peat core analysis (loss on ignition, bulk density, total organic carbon and heavy metal analysis of 298 peat samples) to estimate the amount of peat and carbon stored at Flow Moss. 2) Surface erosion monitoring using sediment traps, fixed pole transects, erosion pins and Terrestrial Laser Scanning (TLS) to establish through which mechanisms peat is eroded and transported. A dGPS survey was implemented and the results compared to historic satellite and UAV imagery to monitor changes in surface vegetation cover. 3) Environmental monitoring of rainfall, wind speed / direction, temperature and water table height. The results are compared with those collected during surface monitoring to identify the drivers of erosion at Flow Moss. Results show that currently there are 4004 (±0.03) tonnes of carbon stored at Flow Moss, which equates to 572 tonnes per ha. At present this is relatively stable, but the site is a slight net source of carbon emitting approximately two tonnes or 0.05% of the stored carbon each year. The bare peat flats are actively eroding with 35 tonnes of sediment being transported by wind-related processes annually. High wind speed and high intensity rainfall are the main drivers of erosion at Flow Moss and their effectiveness increases when they occur concurrently. Sediment and carbon loss from the channel system, although small, has significantly decreased (a reduction of 98%) since the start of restoration. This is most likely due to vegetation encroachment from the margins of the bare peat with a reduction in the bare peat area of 21% occurring since 2007 and a reduction of 997 m2 or 12% occurring since restoration began in 2010. This suggests that that restoration attempts have shown some limited success, however for Flow Moss to become a net carbon store, full re-vegetation of the bare peat is necessary

Cross-shelf circulation and momentum and heat balances over the inner continental shelf near Martha's Vineyard, Massachusetts

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2007.The water circulation and evolution of water temperature over the inner continental shelf are investigated using observations of water velocity, temperature, density, and bottom pressure; surface gravity waves; wind stress; and heat flux between the ocean and atmosphere during 2001-2007. When waves are small, cross-shelf wind stress is the dominant mechanism driving cross-shelf circulation. The along-shelf wind stress does not drive a substantial cross-shelf circulation. The response to a given wind stress is stronger in summer than winter. The cross-shelf transport in the surface layer during winter agrees with a two-dimensional, unstratified model. During large waves and onshore winds the cross-shelf velocity is nearly vertically uniform, because the wind- and wave-driven shears cancel. During large waves and offshore winds the velocity is strongly vertically sheared because the wind- and wave-driven shears have the same sign. The subtidal, depth-average cross-shelf momentum balance is a combination of geostrophic balance and a coastal set-up and set-down balance driven by the cross-shelf wind stress. The estimated wave radiation stress gradient is also large. The dominant along-shelf momentum balance is between the wind stress and pressure gradient, but the bottom stress, acceleration, Coriolis, Hasselmann wave stress, and nonlinear advection are not negligible. The fluctuating along-shelf pressure gradient is a local sea level response to wind forcing, not a remotely generated pressure gradient. In summer, the water is persistently cooled due to a mean upwelling circulation. The cross-shelf heat flux nearly balances the strong surface heating throughout midsummer, so the water temperature is almost constant. The along-shelf heat flux divergence is apparently small. In winter, the change in water temperature is closer to that expected due to the surface cooling. Heat transport due to surface gravity waves is substantial.My last three years of thesis work were supported by National Aeronautics and Space Administration Headquarters under the Earth System Science Fellowship Grant NNG04GQ14H, and by WHOI Academic Programs Fellowship Funds. I also benefited from the freedom of a Clare Boothe Luce Fellowship during my first year in the Joint Program, which allowed me more time than is usual to explore different research topics before choosing an advisor. This research was also funded by the National Aeronautics and Space Administration under grant NNG04GL03G and the Ocean Sciences Division of the National Science Foundation under grants OCE-0241292 and OCE-0548961. The Martha's Vineyard Coastal Observatory is partly funded by the Woods Hole Oceanographic Institution and the Jewett/EDUC/Harrison Foundation. The ADCP deployments at CBLAST site F were funded by National Science Foundation Small Grant for Exploratory Research OCE-0337892. Ship time for deployment and recovery of the F ADCP was provided by Robert Weller through Office of Naval Research contracts N00014-01-1-0029 and N00014-05-10090 for the Low-Wind Component of the Coupled Boundary Layers Air-Sea Transfer Experiment

Classroom Participation Strategy In Principles Of Finance Courses

The challenge of introductory finance courses often surprises junior level university students. This paper describes a strategy that effectively motivates students to prepare solutions to problems for each class and to be prepared to check work presented by classmates. Empirically, the participation grade was found to be positively and significantly related to performance on the final examination while controlling for other performance attributes. Collateral benefits observed included a gradually reduced level of stress in students making presentations and an improved ability to focus on presentations by colleagues whose work they might be called upon to verify and discuss pedagogically

Design management: changing roles of the professions

This paper sets out to explore how recent changes in procurement in construction have affected the roles that professions play in the design process. It discusses how professions that traditionally took the role of design manager now find themselves participating within previously unforeseen contexts, working in multidisciplinary teams led by contractors and with changed responsibilities at the design stage. Supply chain members who were not previously involved during the early project phases are being engaged at the earliest phases of the project life cycle and even taking leadership roles while designers sometimes work as supply chain partners. A study of design in construction and other sectors shows that in dealing with design management issues it is critical to deepen appreciation for the unique characteristics of design and the design process. The paper argues that contractors and designers taking on design management roles in a dynamic industry seeking to explore best practice and innovative approaches to procurement and in the delivery of projects need to acquire new skills, management education and develop the necessary qualities

Optimal Multiple Crop Price Hedging: Robust Estimates Under Yield/Basis Risk

This paper examines how commodity futures can optimally be used by farmers to reduce exposure to price risk in the presence of production uncertainty. The multiple-crop hedging problem is modeled under conditions of price risk, production risk, and basis risk. The results are of general significance for producers with concave utility functions of expected wealth.Optimal hedges are obtained that are quantitatively robust for different wealth levels and for variations in utility functions spanning the plausible range from decreasing to increasing relative risk aversion and for relative risk aversion coefficients of any plausible value.Extensions to the existing literature include a closed form solution that provides robust estimates of optimal hedging strategy for the multiple crop hedging problem under uncertain yields, estimation of the optimal hedge variation as a function of distance from the geographical center of crop production, and optimal hedge estimates for state average crop mixes by state for forty-two states