Acoustic Telemetry Studies of Juvenile Chinook Salmon Survival at the Lower Columbia Projects in 2006

The Portland District of the U.S. Army Corps of Engineers contracted with the Pacific Northwest National Laboratory (PNNL) to conduct three studies using acoustic telemetry to estimate detection probabilities and survival of juvenile Chinook salmon at three hydropower projects on the lower Columbia River. The primary goals were to estimate detection and survival probabilities based on sampling with JSATS equipment, assess the feasibility of using JSATS for survival studies, and estimate sample sizes needed to obtain a desired level of precision in future studies. The 2006 JSATS arrays usually performed as well or better than radio telemetry arrays in the JDA and TDA tailwaters, and underperformed radio arrays in the BON tailwater, particularly in spring. Most of the probabilities of detection on at least one of all arrays in a tailwater exceeded 80% for each method, which was sufficient to provide confidence in survival estimates. The probability of detection on one of three arrays includes survival and detection probabilities because fish may die or pass all three arrays undetected but alive

Survival of Juvenile Chinook Salmon Passing the Bonneville Dam Spillway in 2007

The U.S. Army Corps of Engineers Portland District (CENWP) funds numerous evaluations of fish passage and survival on the Columbia River. In 2007, the CENWP asked Pacific Northwest National Laboratory to conduct an acoustic telemetry study to estimate the survival of juvenile Chinook salmon passing the spillway at Bonneville Dam. This report documents the study results which are intended to be used to improve the conditions juvenile anadromous fish experience when passing through the dams that the Corps operates on the river

Evaluation of a Behavioral Guidance Structure at Bonneville Dam Second Powerhouse including Passage Survival of Juvenile Salmon and Steelhead using Acoustic Telemetry, 2008

Summarizes research conducted at Bonneville Dam in 2008 to evaluate a prototype Behavioral Guidance Structure, that was deployed by the US Army Corps of Engineers in an effort to increase survival of outmigrating smolts at Bonneville Dam

October 1995 magnetic cloud and accompanying storm activity: Ring current evolution

The passage at Earth of the October 1995 magnetic cloud and the high-speed corotating stream overtaking it, monitored by the Global Geospace Science (GGS) spacecraft Wind, caused two consecutive geomagnetic storms: a major one during the strong Bz \u3c 0 nT phase of cloud passage and a moderate one during the intermittent Bz \u3c 0 activity in the fast corotating stream. Large dynamic pressure changes were observed in the sheath region ahead of the cloud and in the cloud-stream interface region at its rear, resulting in substantial corrections to the measured Dst index. A burst of superdense plasma sheet extending over ∼2 hours in local time was observed at geostationary orbit during the second storm. We simulate the ring current development during this storm period using our kinetic model and calculate the magnetic field perturbation caused by the ring current. The plasma inflow on the nightside is modeled throughout the investigated period using data measured at geosynchronous orbit. The modeled Dst index is compared with the observed Dst values corrected for magnetopause and telluric currents. The temporal evolution of the ring current H+ and O+ distribution functions is computed, considering losses due to charge exchange, Coulomb collisions, and ion precipitation. We find that (1) the storm time enhancement of the plasma sheet ion population contributed significantly to the ring current buildup; (2) an additional ∼12 nT decrease in Dst is achieved when the symmetry line of the plasma convection paths is rotated eastward from the dawn-dusk direction with 3 hours during the first storm; (3) the major loss process is charge exchange, followed by Coulomb collisions and ion precipitation; (4) however, the energy losses due to ion precipitation increase monotonically during the more active periods, reaching the level of Coulomb losses at peak storm intensity. We argue that the losses due to ion precipitation considered in this study are closely related to the enhanced convection electric field, which in our model is parameterized with the planetary Kp index. Correspondingly, we find that (5) there is a very good correlation between the variations in time of this index and the magnitude of the ion precipitation losses

Survival Rates of Juvenile Salmonids Passing Through the Bonneville Dam and Spillway in 2008

This report describes a 2008 acoustic telemetry survival study conducted by the Pacific Northwest National Laboratory for the Portland District of the U.S. Army Corps of Engineers. The study estimated the survival of juvenile Chinook salmon and steelhead passing Bonneville Dam (BON) and its spillway. Of particular interest was the relative survival of smolts detected passing through end spill bays 1-3 and 16-18, which had deep flow deflectors immediately downstream of spill gates, versus survival of smolts passing middle spill bays 4-15, which had shallow flow deflectors

High-Resolution Measurements of the Cross-Shock Potential, Ion Reflection, and Electron Heating at an Interplanetary Shock by MMS

International audienceThe Magnetospheric Multiscale (MMS) spacecraft obtained unprecedented high-time resolution multipoint particle and field measurements of an interplanetary shock event on 8 January 2018. The spacecraft encountered the supercritical forward shock of a forward/reverse shock pair in the pristine solar wind upstream of the bow shock near the subsolar point as they neared apogee at 25 RE. The high-time resolution measurements from the four spacecraft, separated by only 20 km, allowed direct measurement of particle distributions revealing evidence of electron heating and near specularly reflected ions. The cross-shock potential is calculated directly from 3-D electric field measurements. This is the first reported direct high temporal resolution (<1 s) observation at an interplanetary shock of near specularly reflected ions. Calculation of the cross-shock potential yields a potential jump significant enough to reflect at least some of the protons from the incident solar wind beam. The cross-shock potential calculated here is consistent with previous estimations based on particle measurements and numerical/analytical simulations. The ambipolar contribution to the cross-shock potential calculated from the four-spacecraft divergence of the electron pressure tensor is somewhat higher than that inferred form the Liouville-mapped electron energy gain across the shock. Furthermore, the high-time-resolution 3-D electric field measurements reported here reveal small-scale nonlinear structures embedded in the shock layer that contribute to the nonmonotonic shock transition