Bio-optical Measurement in the California Current

We measured the optical and bio-geochemical properties during the autumn 2004 CalCOFI cruise. Calibration of in situ radiometry instruments We maintain NIST-traceable calibration of our PRR-800/8 10 radiometers. SIRREX-linked calibrations for our PRR-800/8 10 have been accomplished by Biospherical Instruments, Inc. (BSI) and SDSU Center for Hydro Optics and Remote Sensing (CHORS) since May 1993

Development of moored oceanographic spectroradiometer

Biospherical Instruments has successfully completed a NASA sponsored SBIR (Small Business Innovational Research Program) project to develop spectroradiometers capable of being deployed in the ocean for long periods of time. The completion of this project adds a valuable tool for the calibration of future spaceborne ocean color sensors and enables oceanographers to extend remote sensing optical techniques beyond the intermittent coverage of spaceborne sensors. Highlights of the project include two moorings totalling 8 months generating extensive sets of optical, biological, and physical data sets in the ocean off La Jolla, California, and a 70 day operational deployment of the resulting commercial product by the ONR and NASA sponsored BIOWATT program. Based on experience gained in these moorings, Biospherical Instruments has developed a new line of spectroradiometers designed to support the oceanographic remote sensing missions of NASA, the Navy, and various oceanographers

Physical Drivers of Phytoplankton Bloom Initiation in the Southern Ocean's Scotia Sea

Abstract: The Scotia Sea is the site of one of the largest spring phytoplankton blooms in the Southern Ocean. Past studies suggest that shelf‐iron inputs are responsible for the high productivity in this region, but the physical mechanisms that initiate and sustain the bloom are not well understood. Analysis of profiling float data from 2002 to 2017 shows that the Scotia Sea has an unusually shallow mixed‐layer depth during the transition from winter to spring, allowing the region to support a bloom earlier in the season than elsewhere in the Antarctic Circumpolar Current. We compare these results to the mixed‐layer depth in the 1/6° data‐assimilating Southern Ocean State Estimate and then use the model output to assess the physical balances governing mixed‐layer variability in the region. Results indicate the importance of lateral advection of Weddell Sea surface waters in setting the stratification. A Lagrangian particle release experiment run backward in time suggests that Weddell outflow constitutes 10% of the waters in the upper 200 m of the water column in the bloom region. This dense Weddell water subducts below the surface waters in the Scotia Sea, establishing a sharp subsurface density contrast that cannot be overcome by wintertime convection. Profiling float trajectories are consistent with the formation of Taylor columns over the region's complex bathymetry, which may also contribute to the unique stratification. Furthermore, biogeochemical measurements from 2016 and 2017 bloom events suggest that vertical exchange associated with this Taylor column enhances productivity by delivering nutrients to the euphotic zone

SeaWiFS calibration and validation plan, volume 3

The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) will be the first ocean-color satellite since the Nimbus-7 Coastal Zone Color Scanner (CZCS), which ceased operation in 1986. Unlike the CZCS, which was designed as a proof-of-concept experiment, SeaWiFS will provide routine global coverage every 2 days and is designed to provide estimates of photosynthetic concentrations of sufficient accuracy for use in quantitative studies of the ocean's primary productivity and biogeochemistry. A review of the CZCS mission is included that describes that data set's limitations and provides justification for a comprehensive SeaWiFS calibration and validation program. To accomplish the SeaWiFS scientific objectives, the sensor's calibration must be constantly monitored, and robust atmospheric corrections and bio-optical algorithms must be developed. The plan incorporates a multi-faceted approach to sensor calibration using a combination of vicarious (based on in situ observations) and onboard calibration techniques. Because of budget constraints and the limited availability of ship resources, the development of the operational algorithms (atmospheric and bio-optical) will rely heavily on collaborations with the Earth Observing System (EOS), the Moderate Resolution Imaging Spectrometer (MODIS) oceans team, and projects sponsored by other agencies, e.g., the U.S. Navy and the National Science Foundation (NSF). Other elements of the plan include the routine quality control of input ancillary data (e.g., surface wind, surface pressure, ozone concentration, etc.) used in the processing and verification of the level-0 (raw) data to level-1 (calibrated radiances), level-2 (derived products), and level-3 (gridded and averaged derived data) products

Quantifying energetics and dissipation in magnetohydrodynamic turbulence

We perform a suite of two- and three-dimensional magnetohydrodynamic (MHD) simulations with the Athena code of the non-driven Kelvin-Helmholtz instability in the subsonic, weak magnetic field limit. Focusing the analysis on the non-linear turbulent regime, we quantify energy transfer on a scale-by-scale basis and identify the physical mechanisms responsible for energy exchange by developing the diagnostic known as spectral energy transfer function analysis. At late times when the fluid is in a state of MHD turbulence, magnetic tension mediates the dominant mode of energy injection into the magnetic reservoir, whereby turbulent fluid motions twist and stretch the magnetic field lines. This generated magnetic energy turbulently cascades to smaller scales, while being exchanged backwards and forwards with the kinetic energy reservoir, until finally being dissipated. Incorporating explicit dissipation pushes the dissipation scale to larger scales than if the dissipation were entirely numerical. For scales larger than the dissipation scale, we show that the physics of energy transfer in decaying MHD turbulence is robust to numerical effects.Comment: 23 pages, 20 figures, 4 tables, Accepted for publication in MNRA

Developing a Monitoring Framework to Estimate Wolf Distribution and Abundance in Southwest Alberta

Gray wolf (Canis lupus) populations are difficult to monitor because wolves can be elusive and occur in low densities.  Traditional radiotelemetry-based monitoring methods have limited application when turnover is high within the wolf population and resources to maintain long-term collaring programs are limited.  We worked collaboratively with Alberta Environmental Sustainable Resource Development between 2012 and 2014 to develop techniques for monitoring gray wolf populations in the absence of radiotelemetry in southwest Alberta.  We surveyed potential rendezvous sites and collected DNA samples from wolf scats for genetic analysis and surveyed hunters for wolf sightings made during the hunting seasons. We fit false-positive occupancy models to annual detection data derived from genetic results and hunter surveys with Program PRESENCE.  We found percent forest cover and human density positively influenced pack occupancy whereas detection probabilities varied by survey method, sampling effort, and sampling season.  The model predicted wolf pack occupancy well and distribution and abundance estimates were consistent with agency predictions.  While developing the monitoring framework, questions arose regarding pack turnover and population growth under widespread human harvest.  Previous studies have focused on population recovery following wolf control actions but little emphasis is put on populations that exist under regular harvest.  We will use genetic data to determine how immigration contributes to wolf population trends under a long-term harvest regime and tie this into pack occupancy through colonization and local extinction probabilities.  This will expand the application of our occupancy model and will further clarify how wolf populations respond to long-term regulated harvest

Aspirin May Be Adequate for Venous Thromboembolic Event Prophylaxis after Revision Hip and Knee Arthroplasty

Introduction: The optimal prophylaxis for prevention of venous thromboembolic events (VTE) after total hip arthroplasty (THA) and total knee arthroplasty (TKA) remains unknown.(1) Current studies focus on primary arthroplasty and there are little to no data on the ideal prophylaxis for VTE following revision arthroplasty.(2) Revision surgery, due to its complexity, longer operative time, higher risk of bleeding and infection diff­ers from primary arthroplasty.(3) The objective of this study was to evaluate whether aspirin, known to be e­ffective for prevention of VTE after primary arthroplasty, is also e­ffective against such events following revision THA and TKA

Wolf Pack Distribution in Relation to Heavy Harvest in Southwest Alberta

Gray wolf (Canis lupus) populations are difficult to monitor because wolves can be elusive and occur in low densities.  Harvest can further complicate wolf monitoring by affecting wolf behavior, altering pack structure, and potentially reducing probability of detection.  Currently, Montana and Idaho use patch occupancy models to monitor wolves at state-wide scales.  These models were originally developed prior to the initiation of wolf harvest and there is growing concern that current occupancy estimates are becoming less reliable as harvest continues.  Our objectives were to determine whether we could estimate wolf distribution for a heavily harvested wolf population and assess how harvest may be affecting that distribution.  We surveyed potential rendezvous sites and collected DNA samples from wolf scats for genetic analysis and surveyed hunters for wolf sightings in southwestern Alberta from 2012 to 2014. We used a Bayesian approach to fit dynamic occupancy models to the encounter histories while accounting for false-positive detections using JAGS and Program R.  We found both habitat and anthropogenic factors influenced wolf occupancy parameters in southwestern Alberta and detection probability varied by survey method.  Our preliminary results suggest wolf pack distribution is fairly consistent but that source-sink dynamics may be occurring in certain regions of the study area.  Despite heavy harvest pressure, southwestern Alberta appears to maintain a stable wolf population, although this is possibly due to immigration from nearby regions

Phytoplankton absorption, photosynthetic parameters, and primary production off Baja California: summer and autumn

Abstract To estimate ocean primary production at large space and time scales, it is necessary to use models combined with ocean-color satellite data. Detailed estimates of primary production are typically done at only a few representative stations. To get survey-scale estimates of primary production, one must introduce routinely measured Chlorophyll-a (Chl-a) into models. For best precision, models should be based on accurate parameterizations developed from optical and photosynthesis data collected in the region of interest. To develop regional model parameterizations 14 Cbicarbonate was used to estimate in situ primary production and photosynthetic parameters ða à ; P à m , and E k ) derived from photosynthesis-irradiance (P-E) experiments from IMECOCAL cruises to the southern California Current during July and October 1998. The P-E experiments were done for samples collected from the 50% surface light depth for which we also determined particle and phytoplankton absorption coefficients (a p , a f , and a à f Þ. Physical data collected during both surveys indicated that the 1997-1998 El Nin˜o was abating during the summer of 1998, with a subsequent transition to the typical California Current circulation and coastal upwelling conditions. Phytoplankton chl-a and in situ primary production were elevated at coastal stations for both surveys, with the highest values during summer. Phytoplankton specific absorption coefficients in the blue peak ða à f (440) ) ranged from 0.02 to 0.11 m 2 (mg Chl-a) À1 with largest values in offshore surface waters. In general a à f was lower at depth compared to the surface. P-E samples were collected at the 50% light level that was usually in the surface mixed layer. Using a à and spectral absorption, we estimated maximum photosynthetic quantum yields (f max ; mol C/mol quanta). f max values were lowest in offshore surface waters, with a total range of 0.01-0.07. Mean values of f max for July and October were 0.011 and 0.022, respectively. In July P à m was approximately double and a à was about 1.4 times the values for October. Since the P-E samples were generally within the upper mixed layer, these tendencies in the photosynthetic parameters are attributed to deeper mixing of this layer during October when the mean mixed layer for the photosynthesis stations was 35 m compared to a mean of 10 m in July. Application of a semi-analytical model using mean values of P-E parameters determined at the 50% light depth provided good agreement with 14 C in situ estimates at the discrete 50% light depth and for the water-column integrated primary production.