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Coastal embayments in nearshore upwelling systems (“upwelling bays”) play a disproportionately large role in regional oceanography. In these systems, local diurnal wind forcing and thermal gradients associated with an upwelling shadow front that forms between warmer sheltered waters inside the bay and colder recently upwelled waters outside the bay strongly influence local temperature dynamics. Despite their importance to local ecosystems, there are no long-term studies that assess the heat budget inside upwelling bays. In this study, we analyzed approximately two years of water temperature throughout the water column using an autonomous profiler in a small upwelling bay in central California (San Luis Obispo Bay). We coupled these measurements with local meteorological data and in-situ temperature measurements made outside the bay to investigate how local diurnal wind forcing and the presence of the upwelling shadow front modify the diurnal heat budget inside the bay. Over the study period, strong seasonality in regional upwelling coincided with changes in local wind forcing, front strength (bulk temperature difference between inside and outside the bay), and temperature structure, from which we identified various forcing regimes to quantify the diurnal heat budget. During the non-upwelling season when the front was largely absent, the heat budget was primarily a balance between changes in heat content and surface heat fluxes, regardless of local wind forcing strength. This was also the primary balance during the upwelling season when local winds were weak. In contrast, during the upwelling season when the upwelling shadow front was persistent and the local winds were strong, increasing front strength led to increasingly large residual heat fluxes, which were interpreted to be due to advection (advective fluxes not calculated directly). These results highlight the importance of both local wind forcing and frontal intensity on the heat budget inside the upwelling bay, with significant implications for residence time, temperature dynamics, and local biogeochemistry in similar systems that are ubiquitous globally. 

Transforming agricultural residues into value-added chemicals drives the sustainable development of a biobased economy. The acetosolv process was investigated for the fractionation of corn cobs into cellulose, hemicellulose, and lignin fractions, integrating experimental work with process simulation, techno-economic analysis (TEA), and life cycle assessment (LCA). Laboratory-scale experiments using 70 vol.% acetic acid and 30 vol.% water, catalyzed with sulfuric acid, yielded 48.2 ± 1.9 wt.% cellulose and 15.1 ± 1.2 wt.% lignin, with a solvent recovery of 96.0 ± 1.5 vol.%. Gas chromatography analysis indicated the formation of ethyl acetate as byproduct from acid-catalyzed esterification between acetic acid and ethanol, used as a washing solvent. The acetosolv process was simulated using Aspen Plus® software, assuming corn cob processing capacity of 150 ktons/y and current market prices for the three product fractions (cellulose, hemicellulose and lignin), The formation of these fractions in the acetosolv reactor along the downstream separation of acetic acid, ethanol and ethyl acetate was modeled. TEA results predict that the process could operate profitably based on the assumed market prices for cellulose, hemicellulose and lignin. Both capital and operating costs are dominated by unit operations associated with solvent handling and recovery. Sensitivity analysis indicated that process profitability was preserved when considering experimentally observed variances in the yields of the three fractions. Further valorization of the cellulose, hemicellulose and lignin fractions would thus increase profit margins. LCA predicted a climate change impact of 0.22 kg CO₂-eq/kg feedstock, which is in the range reported for organosolv processes. The acetosolv fractions and renewable products made from them have the potential to generate carbon credits which could reduce the overall carbon footprint of the corn ethanol industry.Not Available