scholarly journals Exploiting White-Light Observations to Improve Estimates of Magnetic Connectivity

2021 ◽  
Vol 8 ◽  
Author(s):  
Nicolas Poirier ◽  
Alexis P. Rouillard ◽  
Athanasios Kouloumvakos ◽  
Alexis Przybylak ◽  
Naïs Fargette ◽  
...  
Keyword(s):  
White Light ◽  
Solar Wind Plasma ◽  
Magnetic Polarity ◽  
Model Parameters ◽  
The Sun ◽  
Heliospheric Observatory ◽  
Practical Applications ◽  
One Year ◽  
First Time

The Solar Orbiter (SolO) and Parker Solar Probe missions have opened up new challenges for the heliospheric scientific community. Their proximity to the Sun and their high quality measurements allow us to investigate, for the first time, potential sources for the solar wind plasma measured in situ. More accurate estimates of magnetic connectivities from spacecraft to the Sun are required to support science and operations for these missions. We present a methodology to systematically compare coronal and heliospheric models against white-light (WL) observations. WL images from the SOlar and Heliospheric Observatory (SoHO) are processed to unveil the faint structures of the K-corona. Images are then concatenated over time and are projected into a Carrington synoptic map. Features of interest such as the Streamer Belt (SB) are reduced to simplified geometric objects. Finally, a metric is defined to rank models according to their performance against WL observations. The method has been exploited to reproduce magnetic sectors from WL observations. We tested our results against one year of in situ magnetic polarity measurements taken at near one AU from the Advanced Composition Explorer (ACE) and the Solar TErrestrial RElations Observatory (STEREO-A). We obtained a good correlation that emphasizes the relevance of using WL observations to infer the shape of the sector structure. We show that WL observations provide additional constraints to better select model parameters such as the input photospheric magnetic map. We highlight the capability of this technique to systematically optimize coronal and heliospheric models using continuous and near-real-time WL observations. Several relevant practical applications are discussed, which should allow us to improve connectivity estimates.

Gravitational and Coulomb Potentials Interference in Heliosphere

2020 ◽  
pp. 93-121
Author(s):  
P.I. Vysikaylo ◽  
N.S. Ryabukha
Keyword(s):  
Solar Wind ◽  
Solar Wind Plasma ◽  
The Sun ◽  
Number Density ◽  
Heavy Particles ◽  
Debye Theory ◽  
Experimental Values ◽  
First Time ◽  
Small Charge ◽  
Coulomb Potentials

Interference of gravitational and Coulomb potentials in the entire heliosphere is considered, it is being manifested in generation of two opposite flows of charged particles: 1) that are neutral or with a small charge to the Sun, and 2) in the form of a solar wind from the Sun. According to the Einstein --- Smoluchowski relation Te(R) = eDe / µe ~ (E/N)0.75 based on the N experimental values (heavy particles number density --- the ne electron concentration), the Te electron temperature in the entire heliosphere was for the first time analytically calculated depending on the charge of the Sun and distance to it R. Calculated values of the registered ion parameters in the solar wind were compared with experimental observations. Reasons for generating the ring current in inhomogeneous heliosphere and inapplicability of the Debye theory in describing processes in the solar wind (plasma with current) are considered

scholarly journals Integrative modelling of animal movement: incorporating in situ habitat and behavioural information for a migratory marine predator

2013 ◽  
Vol 280 (1750) ◽  
pp. 20122262 ◽  
Author(s):  
Sophie Bestley ◽  
Ian D. Jonsen ◽  
Mark A. Hindell ◽  
Christophe Guinet ◽  
Jean-Benoît Charrassin
Keyword(s):  
Process Model ◽  
Animal Movement ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Model Parameters ◽  
Mirounga Leonina ◽  
Marine Predator ◽  
Fundamental Goal ◽  
First Time

A fundamental goal in animal ecology is to quantify how environmental (and other) factors influence individual movement, as this is key to understanding responsiveness of populations to future change. However, quantitative interpretation of individual-based telemetry data is hampered by the complexity of, and error within, these multi-dimensional data. Here, we present an integrative hierarchical Bayesian state-space modelling approach where, for the first time, the mechanistic process model for the movement state of animals directly incorporates both environmental and other behavioural information, and observation and process model parameters are estimated within a single model. When applied to a migratory marine predator, the southern elephant seal ( Mirounga leonina ), we find the switch from directed to resident movement state was associated with colder water temperatures, relatively short dive bottom time and rapid descent rates. The approach presented here can have widespread utility for quantifying movement–behaviour (diving or other)–environment relationships across species and systems.

scholarly journals Estimation of ship emission rates at a major shipping lane by long path DOAS measurements

2021 ◽  
Author(s):  
Kai Krause ◽  
Folkard Wittrock ◽  
Andreas Richter ◽  
Stefan Schmitt ◽  
Denis Pöhler ◽  
...  
Keyword(s):  
Emission Factors ◽  
Emission Rates ◽  
River Elbe ◽  
Gaussian Plume ◽  
Remote Sensing Techniques ◽  
One Year ◽  
First Time ◽  
Good Agreement ◽  
Ship Emission

Abstract. Ships are an important source of SO2 and NOx, which are key parameters of air quality. Monitoring of ship emissions is usually carried out using in situ instruments on land, which depend on favourable wind conditions to transport the emitted substances to the measurement site. Remote sensing techniques such as long path DOAS (LP-DOAS) measurements can supplement those measurements, especially in unfavourable meteorological conditions. In this study one year of LP-DOAS measurements made across the river Elbe close to Hamburg (Germany) have been evaluated. Peaks (i.e. elevated concentrations) in the NO2 and SO2 time series were assigned to passing ships and a method to derive emission rates of SO2, NO2 and NOx from those measurements using a Gaussian plume model is presented. 7402 individual ship passages have been monitored and their respective NOx, SO2 and NO2 emission rates have been derived. The emission rates, coupled with the knowledge of the ship type, ship size and ship speed have been analysed. Emission rates are compared to emission factors from previous studies and show good agreement. In contrast to emission factors (in gram per kilogram fuel) the derived emission rates (in gram per second) do not need further knowledge about the fuel consumption of the ship. To our knowledge this is the first time emission rates of air pollutants from individual ships have been derived from LP-DOAS measurements.

scholarly journals The RPW Low Frequency Receiver (LFR) on Solar Orbiter: in-situ LF electric and magnetic field measurements of the solar wind expansion

2020 ◽  
Author(s):  
Thomas Chust ◽  
Olivier Le Contel ◽  
Matthieu Berthomier ◽  
Alessandro Retinò ◽  
Fouad Sahraoui ◽  
...  
Keyword(s):  
Solar Wind ◽  
Low Frequency ◽  
Field Measurements ◽  
Solar Wind Plasma ◽  
Wind Condition ◽  
The Sun ◽  
Nasa Mission ◽  
Magnetic Field Measurements ◽  
Electric And Magnetic Field

<p>Solar Orbiter (SO) is an ESA/NASA mission for exploring the Sun-Heliosphere connection which has been launched in February 2020. The Low Frequency Receiver (LFR) is one of the main subsystems of the Radio and Plasma Wave (RPW) experiment on SO. It is designed for characterizing the low frequency (~0.1Hz–10kHz) electromagnetic fields & waves which develop, propagate, interact, and dissipate in the solar wind plasma. In correlation with particle observations it will help to understand the heating and acceleration processes at work during its expansion. We will present the first LFR data gathered during the Near Earth Commissioning Phase, and will compare them with MMS data recorded in similar solar wind condition.</p>

An in Situ Dual Indentation and Optimization Method to Determine Mechanical Properties of Articular Cartilage

2007 ◽  
Author(s):  
Jonathan E. Pottle ◽  
J.-K. Francis Suh
Keyword(s):  
Articular Cartilage ◽  
Stress Relaxation ◽  
Structural Integrity ◽  
Reaction Force ◽  
Model Parameters ◽  
Unconfined Compression ◽  
Confined Compression ◽  
Practical Applications

The efficacy of the biphasic poroviscoelastic (BPVE) theory [1] in constitutive modeling of articular cartilage biomechanics is well-established [2–4]. Indeed, this model has been used to simultaneously predict stress relaxation force across confined compression, unconfined compression, and indentation protocols [2,3]. Previous works have also demonstrated success in simultaneously curve-fitting the BPVE model to reaction force and lateral deformation data gathered from stress relaxation tests of articular cartilage in unconfined compression [4]. However, a potential limitation of practical applications of such a successful model is seen in some commonly-employed mechanical testing methods for articular cartilage, such as confined compression and unconfined compression. These methods require the excision of a disk of cartilage from its underlying subchondral base, which likely would compromise the structural integrity of the tissue, causing swelling and curling artifacts of the sample [5]. Indentation represents a testing protocol that can be used with an intact cartilage layer. This results in a specimen more closely resembling cartilage in vivo. Using an agarose gel construct, our previous study [6] has demonstrated that a unique set of the six BPVE model parameters of a soft tissue can be determined readily from in situ dual indentation method using stress relaxation and creep viscoelastic protocols. The objective of the current study is to validate the efficacy of this technique as a means to determine the BPVE material parameters of articular cartilage.

Unique heliophysics science opportunities along the Interstellar Probe journey up to 1000 AU from the Sun

2021 ◽  
Author(s):  
Elena Provornikova ◽  
Pontus C. Brandt ◽  
Ralph L. McNutt, Jr. ◽  
Robert DeMajistre ◽  
Edmond C. Roelof ◽  
...  
Keyword(s):  
Space Mission ◽  
In Situ Measurements ◽  
Unique Determination ◽  
The Sun ◽  
Global Shape ◽  
Wide Range ◽  
First Time ◽  
Interstellar Probe ◽  
Probe Mission

<p>The Interstellar Probe is a space mission to discover physical interactions shaping globally the boundary of our Sun`s heliosphere and its dynamics and for the first time directly sample the properties of the local interstellar medium (LISM). Interstellar Probe will go through the boundary of the heliosphere to the LISM enabling for the first time to explore the boundary with a dedicated instrumentation, to take the image of the global heliosphere by looking back and explore in-situ the unknown LISM. The pragmatic concept study of such mission with a lifetime 50 years that can be implemented by 2030 was funded by NASA and has been led by the Johns Hopkins University Applied Physics Laboratory (APL). The study brought together a diverse community of more than 400 scientists and engineers spanning a wide range of science disciplines across the world.</p><p>Compelling science questions for the Interstellar Probe mission have been with us for many decades. Recent discoveries from a number of space missions exploring the heliosphere raised new questions strengthening the science case. The very shape of the heliosphere, a manifestation of complex global interactions between the solar wind and the LISM, remains the biggest mystery. Interpretations of imaging the heliosphere in energetic neutral atoms (ENAs) in different energy ranges on IBEX and Cassini/INCA from inside show contradictory pictures. Global physics-based models also do not agree on the global shape. Interstellar Probe on outbound trajectory will image the heliosphere from outside for the first time and will provide a unique determination of the global shape.</p><p>The LISM is a completely new area for exploration and discovery. We have a crude understanding of the LISM inferred from in-situ measurements inside the heliosphere of interstellar helium, pick-up-ions, ENAs, remote observations of solar backscattered Lyman-alpha emission and absorption line spectroscopy in the lines of sight of stars. We have no in-situ measurements of most LISM properties, e.g. ionization, plasma and neutral gas, magnetic field, composition, dust, and scales of possible inhomogeneities. Voyagers with limited capabilities have explored 30 AU beyond the heliosphere which appeared to be a region of significant heliospheric influence. The LISM properties are among the key unknowns to understand the Sun`s galactic neighborhood and how it shapes our heliosphere. Interstellar Probe will be the first NASA mission to discover the very nature of the LISM and shed light on whether the Sun enters a new region in the LISM in the near future.</p><p>In this presentation we give an overview of heliophysics science for the Interstellar Probe mission focusing on the critical science questions of the three objectives for the mission. We will discuss in more details a need for direct measurements in the LISM uniquely enabled by the Interstellar Probe.</p>

Solar Orbiter: Europe's mission to the Sun

2020 ◽  
Author(s):  
Yannis Zouganelis ◽  
Daniel Mueller ◽  
Chris St Cyr ◽  
Holly Gilbert ◽  
Teresa Nieves-Chinchilla
Keyword(s):  
High Spatial Resolution ◽  
Solar Wind Plasma ◽  
Ecliptic Plane ◽  
Current Status ◽  
Polar Regions ◽  
The Sun ◽  
Physical Processes ◽  
New Perspective ◽  
Orbiter Mission

<p><span>ESA’s Solar Orbiter mission is scheduled for launch in February 2020, and will focus on exploring the linkage between the Sun and the heliosphere. It is a collaborative mission with NASA that will collect unique data that will allow us to study, e.g., the coupling between macroscopic physical processes to those on kinetic scales, the generation of solar energetic particles and their propagation into the heliosphere, and the origin and acceleration of solar wind plasma. By approaching as close as 0.28 AU, Solar Orbiter will view the Sun with high spatial resolution and combine this with in-situ measurements of the surrounding heliosphere. Over the course of the mission, the highly elliptical orbit will get progressively more inclined to the ecliptic plane. Thanks to this new perspective, Solar Orbiter will deliver images and comprehensive data of the unexplored Sun’s polar regions and the side of the Sun not visible from Earth. This talk will provide a mission overview, highlight synergies with NASA’s Parker Solar Probe and summarise current status.</span></p>

The Whales of Pender Harbour

Orca ◽  
2018 ◽  
Author(s):  
Jason M. Colby
Keyword(s):  
Family Members ◽  
San Juan ◽  
The Sun ◽  
Growing Up ◽  
Killer Whales ◽  
Late Afternoon ◽  
Gill Net ◽  
One Year ◽  
First Time

By early 1968 , Cecil Reid Jr. had given some thought to orcas. A gill net fisherman based in Pender Harbour, the thirty-one-year-old Reid—“Sonny” to his friends—had seen many killer whales over the years. As a boy growing up in the 1940s, he heard locals grumble about blackfish, and he watched family members take shots at the animals as they passed by. “My grandfather lived out around the corner from Irvine’s Landing,” he recalled, “and when the whales showed up, they would get the guns out and start shooting them.” Yet Reid knew live killer whales had become lucrative commodities, and when his father suggested catching one, he decided to give it a try. It was winter, however, and there weren’t many orcas around. Then, to his surprise, they came to him. In the late afternoon of Wednesday, February 21, a pod wandered into Pender Harbour, passing Reid’s waterfront home on Garden Bay. Momentarily stunned, Reid raced down to his boat, Instigator One. “I just happened to have my San Juan net still on the drum—which is a lot deeper and touched bottom,” he later recounted. “So when they came into Garden Bay the first time, I just set my net across.” The whales eluded his first attempt, but they lingered in the harbor, and the following morning Reid convinced other fishermen to help him, including several of his brothers and members of the local Cameron and Gooldrup families. In all, nine fishermen worked to seal off Garden Bay, and as the sun set over Irvine’s Landing, Reid felt certain they had trapped at least three orcas. But that night, one of the nets tore loose, and in the morning only one whale remained. Disappointed, Reid and his partners secured the animal—a fifteen-footer they believed to be male. Like those caught previously, the trapped orca hesitated to challenge the frail net surrounding him, much to the fishermen’s relief. Within minutes, the animal was swimming placidly in its makeshift enclosure. “Maybe it likes it here,” mused Reid.

Interstellar Probe: Pushing the Frontier of Space Science

2020 ◽  
Author(s):  
Pontus Brandt ◽  
Kathleen Mandt ◽  
Elena Provoronikova ◽  
Casey Lisse ◽  
Kirby Runyon ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Kuiper Belt ◽  
Electrical Power ◽  
International Studies ◽  
The Sun ◽  
Gravity Assist ◽  
Trade Offs ◽  
First Time ◽  
Interstellar Probe

<p>An Interstellar Probe beyond our heliosphere in to the largely unexplored interstellar medium (ISM) would be the furthest and boldest step in robotic space exploration ever taken. A dedicated payload of in-situ and remote sensing instruments would uncover the new regime of physics at work in the heliospheric boundary region and offer the first external view of the global heliosphere that is currently missing in the family portrait of all other types of astrospheres observed. Beyond about 400 AU the Probe would reach the ISM and for the first time begin its sampling of the properties of the local interstellar cloud (LIC) that our Sun and neighboring star systems are immersed in.</p><p>An Interstellar Probe has been discussed since around 1960 in several NASA and international studies. The compelling science objectives have remained almost unchanged and are focused on understanding the plasma physics in the interaction region between the heliosphere and the ISM. Their importance have been amplified by the recent unexpected findings by the Voyager 1 and 2 spacecraft that are nearing their end of life at less than 150 AU from the Sun. Remote observations in Energetic Neutral Atoms (ENAs) by the NASA IBEX and Cassini missions have made the remarkable discoveries of ENA emission morphologies that have come as a complete surprise and still lack a satisfactory explanation. Hubble Space Telescope observations have now also made it clearer that the Sun is about to exit the LIC and perhaps already has, which is a unique event of astronomical scales that an Interstellar Probe could explore in-situ for the first time. In addition to these top-priority objectives, contributions of unprecedented science value to planetary sciences and astrophysics are possible including flybys of at least one Kuiper Belt Object, in-situ and remote observations of the dust debris disk, and the extra-galactic background light.</p><p>Here we review the outstanding questions and current state of understanding of the global heliosphere, the ISM and what planetary and astrophysics augmentations can offer. We summarize the compelling science case for an Interstellar Probe, including a range of possible science payloads and the associated operation scenarios. The results stem from the study of a Pragmatic Interstellar Probe currently underway, funded by NASA, and led by The Johns Hopkins University Applied Physics Laboratory with active participation from a large, international team of scientists and engineers. The study focuses on finding realistic mission architectures among a trade space of propulsion options, trajectories, risks and reliability challenges. The study considers operation out to 1000 AU, a survival probability of 85% over 50 years and electrical power of no less than 400 W at the beginning of mission. Over twice the speed of Voyager 1 (the fastest spacecraft currently) has already been achieved in the design using conventional propulsion, with a direct inject to Jupiter followed by a Jupiter Gravity Assist. In order to provide input requirements to the mission study, several possible payloads with different mass allocations and associated mission requirements, trade-offs and risks have been identified.</p>

scholarly journals 2.1.2 Preliminary Results of the Micrometeoroid Experiment on Board Helios A

1976 ◽  
Vol 31 ◽  
pp. 159-163
Author(s):  
E. Grün ◽  
J. Kissel ◽  
H. Fechtig ◽  
P. Gammelin ◽  
H.-J. Hoffmann
Keyword(s):  
Interplanetary Dust ◽  
Strong Increase ◽  
The Sun ◽  
Impact Rate ◽  
M 10 ◽  
Large Particles ◽  
The Impact ◽  
First Time ◽  
Measured Particle

AbstractFor the first time in situ measurements of interplanetary dust have been performed between 0.3 AU and 1 AU from the sun by the micrometeoroid experiment on board Helios A. The measured particle masses are between 10−15 g and 10−8 g and their measured speeds are between 2 km/sec and 20 km/sec. Particle impacts are identified by the time-of-flight spectra of the ions released upon impact. 15 large particles (m ≥ 10−12 g) were detected from Dec. 15, 1974 to Sept. 5, 1975. They show a strong increase of the impact rate (appr. a factor of 10) between 1 AU and 0.3 AU. The directions from which they impacted the sensor are concentrated between the solar direction and the apex direction of the Helios spacecraft.

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