scholarly journals Relationships between snowfall density and solid hydrometeors, based on measured size and fall speed, for snowpack modeling applications

2016 ◽  
Vol 10 (6) ◽  
pp. 2831-2845 ◽  
Author(s):  
Masaaki Ishizaka ◽  
Hiroki Motoyoshi ◽  
Satoru Yamaguchi ◽  
Sento Nakai ◽  
Toru Shiina ◽  
...  
Keyword(s):  
Mass Flux ◽  
Weather Forecasting ◽  
Initial Density ◽  
Quantitative Relationship ◽  
Temperate Climate ◽  
Snowfall Event ◽  
Fall Speed ◽  
Average Size ◽  
Meteorological Elements ◽  
The Relationship

Abstract. The initial density of deposited snow is mainly controlled by snowfall hydrometeors. The relationship between snowfall density and hydrometeors has been qualitatively examined by previous researchers; however, a quantitative relationship has not yet been established due to difficulty in parameterizing the hydrometeor characteristics of a snowfall event. Thus, in an earlier study, we developed a new variable, the centre of mass flux distribution (CMF), which we used to describe the main hydrometeors contributing to a snowfall event. The CMF is based on average size and fall speed weighted by the mass flux estimated from all measured hydrometeors in a snowfall event. It provides a quantitative representation of the predominant hydrometeor characteristics of the event. In this study, we examine the relationships between the density of newly fallen snow and predominant snow type as indicated by the CMFs. We measured snowfall density at Nagaoka, Japan, where riming and aggregation are predominant, simultaneously observing the size and fall speed of snowfall hydrometeors, and deduced the predominant hydrometeor characteristics of each snowfall event from their CMFs. Snow density measurements were carried out for short periods, 1 or 2 h, during which the densification of the deposited snow was negligible. Also, we grouped snowfall events based on similar hydrometeor characteristics. As a result, we were able to obtain not only the qualitative relationships between the main types of snow and snowfall density as reported by previous researchers, but also quantitative relationships between snowfall density and the CMF density introduced here. CMF density is defined as the ratio between mass and volume, assuming the diameter of a sphere is equal to the CMF size component. This quantitative relationship provides a means for more precise estimation of snowfall density based on snow type (hydrometeor characteristics), by using hydrometeor size and fall speed data to derive initial densities for numerical snowpack models, and the snow-to-liquid ratio for winter weather forecasting. In fact, we found that this method can more accurately estimate snowfall density compared with using meteorological elements, which is the method generally used in current snowpack models, even though some issues remain in parameterization for practical use. Transferability of the method developed in the temperate climate zone, where riming and aggregation are predominant, to other snowy areas is also an issue. However, the methodology presented in this study would be useful for other kinds of snow.

scholarly journals Relationships between Snowfall Densities and the Main Types of Solid Hydrometeors Deduced from Measured Size and Fall Speed, for snowpack modeling applications

2016 ◽  
Author(s):  
Masaaki Ishizaka ◽  
Hiroki Motoyoshi ◽  
Satoru Yamaguchi ◽  
Sento Nakai ◽  
Toru Shina ◽  
...  
Keyword(s):  
Numerical Model ◽  
Mass Flux ◽  
Flux Distribution ◽  
Center Of Mass ◽  
Quantitative Relationship ◽  
Snow Pack ◽  
Observation Site ◽  
Predominant Type ◽  
Snowfall Event ◽  
Fall Speed

Abstract. Initial densities of deposited snows mainly depend on hydrometeors types of snowfalls. Some previous researchers qualitatively indicated their relations. However a quantitative relationship between snowfall densities and hydrometeors types had not been established because of difficulty in parameterizing varieties of types of hydrometeors in a snowfall event. Thus in a previous study, we introduced a new variable, CMF (Center of Mass Flux distribution), which described the hydrometeors mainly contributing to a snowfall. The CMF is a set of the averages of the size and the fall speed weighted by the mass flux estimated from all measured hydrometeors in a snowfall. It represents the predominant type of hydrometeors of the snowfall quantitatively. In this study, we examined the relationships between the densities of newly fallen snows and their predominant snow types as indicated by the CMFs. We measured the snowfall densities, simultaneously observing the size and the fall speed of the hydrometeors of the snowfalls and deduced the predominant hydrometeor types of each snowfall event from their CMFs. The measurements of snow densities were carried out for short periods, 1 or 2 h, during which the densification of the deposited snows was negligible. We also selected cases when snowfalls contained basically the same type of hydrometeors. As a result, we could obtain the relationships between the main snow types and the snowfall densities not only qualitatively reported by previous researchers but also the quantitative relationships between snowfall densities and the CMF-densities, which were a presumed density derived from the size and mass components of the CMFs. This suggests the possibility of estimating snowfall densities, which reflected snow types (the main types of hydrometeors), directly from the measured size and the fall speed data, and using them as the initial densities for a snow pack in a numerical model, even though difficult issues remain in parameterization for a plactical use. Our results might be applicable only to temperate snow at our observation site, Nagaoka, 37°N, where riming and aggregation are predominant. However the methodology in this study would be useful for other kinds of snow.

RESOURCE UTILIZATION BY THE SOUTHERN PINE BEETLE, DENDROCTONUS FRONTALIS (COLEOPTERA: SCOLYTIDAE)

1976 ◽  
Vol 108 (4) ◽  
pp. 353-362 ◽  
Author(s):  
Robert N. Coulson ◽  
Adil M. Mayyasi ◽  
J. L. Foltz ◽  
F. P. Hain ◽  
W. C. Martin
Keyword(s):  
Pinus Taeda ◽  
Resource Utilization ◽  
Loblolly Pine ◽  
Quantitative Relationship ◽  
Dendroctonus Frontalis ◽  
Adult Density ◽  
Pine Beetle ◽  
Basal Portion ◽  
Relationship Of ◽  
The Relationship

AbstractThe process of resource utilization by Dendroctonus frontalis Zimmerman attacking loblolly pine, Pinus taeda L., was investigated. The quantitative relationship of attacking parent adult D. frontalis as a function of the normalized infested bole height is described by the model y = Ax(1−x)eBx. Greatest attack density occurs at the mid-bole of the tree and tapers toward the top and bottom. Gallery length (and hence eggs)/100 cm2 was independent of attack density. The relationship between gallery length (or eggs) per parent adult and parent adult density is described by the exponential decay curve y = AeBx, indicating that gallery length and egg population density are controlled by a density dependent compensatory feedback process operating instantaneously. Further support for the mechanism was obtained by analyzing the gallery length per parent adult at different locations on the infested bole. The relationship is described by the model y = [AeBx]/[x(1−x)] and indicates that gallery construction and egg population per attacking beetle increase in the upper and basal portion of the bole. The result is a uniform amount of food and space per individual of the developing population.

scholarly journals Propagation of Stress Waves in Alpine Snow

1980 ◽  
Vol 26 (94) ◽  
pp. 235-243 ◽  
Author(s):  
R. L. Brown
Keyword(s):  
High Frequency ◽  
Wave Speed ◽  
Initial Density ◽  
Pressure Jump ◽  
Pressure Waves ◽  
Speed Increase ◽  
Final Density ◽  
Attenuation Rate ◽  
High Frequency Waves ◽  
The Relationship

AbstractThe propagation of pressure waves in low-density snow is investigated analytically to determine the variation of wave pressure and wave speed with density and frequency. The results show that, for pressure waves that produce finite volumetric deformations, both pressure jump across the wave and wave-speed increase with initial density and final density. The pressure jump was also found to increase with the wave frequency if other parameters were held constant, although the dependence on frequency is not as strong as the dependence on the initial and final densities. The relationship between pressure jump and frequency implies that high-frequency waves would tend to dissipate more quickly than lower-frequency waves, although like pressure, the attenuation rate would not be strongly frequency dependent.

The Relationship Between Internalization of Magnetic Nanoparticles and Changes of Cellular Optical Scatter Signal

2008 ◽  
Vol 8 (12) ◽  
pp. 6310-6315
Author(s):  
Jingguang Xia ◽  
Song Zhang ◽  
Yu Zhang ◽  
Ming Ma ◽  
Kang Xu ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Magnetic Nanoparticles ◽  
Argon Laser ◽  
Human Hepatoma Cells ◽  
Cellular Iron ◽  
High Viability ◽  
A Cell ◽  
Magnetic Labeling ◽  
Average Size ◽  
The Relationship

Carboxylmethyl starch sodium-coated magnetic nanoparticles (CMS@MNs) with average size of 10 nm were synthesized by chemical coprecipitation. Cellular iron content showed that CMS@MNs could be efficiently uptaken by human hepatoma cells. TEM image showed that clusters consisting of nanoparticles were enclosed within sub-micrometric endosomes and one cell contained several such endosomes. After incubation with the nanoparticles, a phenomenon appeared that the intensity of cellular side scatter signal (SSC) obtained by flow cytometry at 488 nm argon laser increased. It was demonstrated that the increase of SSC signal was induced by a cell itself, and mainly caused by the nanoparticles both adsorbed on the membrane and internalized into cytoplasm. Although without inducing cell death the treatments with the nanoparticles could lead to increased permeability of cell membrane to propidium iodide. Results implied a potential that flow cytometry might be used as a tool to rapidly evaluate and select cells with high magnetic labeling and high viability in cellular transplant.

scholarly journals Evaluation of the impact of meteorological conditions on the amount of air pollution in Krakow

2019 ◽  
Vol 108 ◽  
pp. 02012
Author(s):  
Małgorzata Piaskowska-Silarska ◽  
Krzysztof Pytel ◽  
Stanisław Gumuła ◽  
Wiktor Hudy
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Measurement Data ◽  
Ecological Monitoring ◽  
Meteorological Conditions ◽  
Pollution Problem ◽  
Air Quality Improvement ◽  
Meteorological Elements ◽  
The Impact ◽  
The Relationship

Abstract. The publication presents an assessment of the impact of meteorological conditions on air quality in a given location. The subject matter of the work is related to problem-review issues in the field of environmental protection and energy management. The publication draws attention to the fact that despite several decades of ecological monitoring of air pollution, only in recent years attention has been paid to the scale of air pollution problem. The study examined the relationship between meteorological elements (wind velocity, relative humidity on the amount of air pollution immissions. Significant impact of precipitation, atmospheric pressure and thermal braking layer was indicated. The possibilities of air quality improvement were presented based on the measurement data concerning the immission of impurities.

scholarly journals Analyses of Monthly Discharges in Slovakia Using Hydrological Exploratory Methods

Proceedings ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 18
Author(s):  
Mária Ďurigová ◽  
Dominika Ballová ◽  
Kamila Hlavčová
Keyword(s):  
Change Points ◽  
Hydrological Data ◽  
Pettitt Test ◽  
The Mean ◽  
Monthly Discharge ◽  
Meteorological Elements ◽  
The Relationship ◽  
Annual Discharge ◽  
Hydrological Regimes

Detailed analyses of hydrological data are necessary in order to prove changes in their character. This article focuses on an analysis of the average monthly discharges of 14 stage-discharge gauging stations in Slovakia. The measured period is from 1931 to 2016. The approaches used are hydrological exploration methods, which were created by hydrologists to describe the behavior of hydrological time series. The methods are used to identify a change-point using an analysis of any residuals, the Pettitt test, and an analysis of the relationship between the mean annual discharge deviations from the long-term annual discharge and the deviations of the average monthly discharge from the long-term average monthly discharge. A considerable number of change-points were identified in the 1970s and 1980s. The results of the analyses show changes in the hydrological regimes, but to confirm the accuracy of the outcomes, it is also necessary to examine other hydrological and meteorological elements such as, e.g., precipitation and the air temperature.

Defining the Relationship of Magnetohydrodynamic Voltages and Magnetic Field Strength

2017 ◽  
Author(s):  
Kevin J. Wu ◽  
T. Stan Gregory ◽  
Michael C. Lastinger ◽  
Brian Boland ◽  
Zion Tsz Ho Tse
Keyword(s):  
Magnetic Field ◽  
Blood Flow ◽  
Field Strength ◽  
Aortic Arch ◽  
Magnetic Field Strength ◽  
Quantitative Relationship ◽  
Solution Concentration ◽  
Exercise Stress ◽  
Induced Voltage ◽  
The Relationship

The magnetohydrodynamic (MHD) effect is observed in flowing electrolytic fluids and their interactions with magnetic fields. The magnetic field (B0), when perpendicular with the electrolytic fluid flow (μ), causes the shift of the charged particles in the fluid to shift across the length of the vessel (L) normal to the plane of B0 and flow, creating a voltage (VMHD) observable through voltage potential measurements across the flow (Eqn. 1)[1].(1)VMHD=∫0Lu⇀×B0⇀·dL⇀In the medical field, this phenomenon is commonly encountered inside of a human body inside of an MRI machine (Fig. 1). The effect appears most prominently inside the aortic arch due to orientation and size, and is a large contributing factor to noise observed in intra-MRI ECGs [2, 3]. Traditionally, this MHD induced voltage (VMHD) was filtered out to obtain clean intra-MRI ECGs, but recent studies have shown that the VMHD induced in a vessel is related to the blood flow through it (stroke volume in the case of the aortic arch) [4]. Further proof of this relationship can be shown from the increase in VMHD measured from periphery blood vessels during periods of elevated heart rate from exercise stress, when compared to baseline state [5]. Previously, a portable device was built to utilize induced VMHD as an indicator of flow [6]. The device was capable of showing change in blood flow, utilizing a blood flow metric obtained from VMHD, however a quantitative relationship between VMHD and blood flow has yet to be established. This study aims to define the relationship between induced VMHD and magnetic field strength in a controlled setting. Through modulating the distance between a pair of magnets around a flow channel, we hope to better realize the relationship between magnetic field strength and induced VMHD with constant flow and electrolytic solution concentration.

Quantitative Relationship between Strain and Acoustic Emission Response in Monitoring Fatigue Damage

2013 ◽  
Vol 66 (1) ◽  
Author(s):  
M. Mohammad ◽  
S. Abdullah ◽  
N. Jamaludin ◽  
O. Innayatullah
Keyword(s):  
Acoustic Emission ◽  
Failure Mechanism ◽  
Fatigue Failure ◽  
Quantitative Relationship ◽  
Steel Specimen ◽  
Cyclic Fatigue ◽  
Steel Component ◽  
Specific Data ◽  
The Relationship ◽  
Ae Signals

This study was carried out to investigate the relationship between the strain and acoustic emission (AE) signals, thus, to confirm the capability of AE technique to monitor the fatigue failure mechanism of a steel component. To achieve this goal, strain and AE signals were captured on the steel specimen during the cyclic fatigue test.  Both signals were collected using specific data acquisition system by attaching the strain gauge and AE piezoelectric transducer simultaneously at the specimen during the test. The stress loading used for the test was set at 600 MPa, and the specimens were fabricated using the SAE 1045 carbon steel.  The related parameters for both signals were determined at every 2000 seconds until the specimen failed.  It was found that a meaningful correlation of all parameters, i.e. amplitude, kurtosis and energy, was established. Finally, all AE parameters are correlated with the damage values, which have been estimated using the Coffin-Manson model.  Hence, it was suggested that the AE technique can be used as a monitoring tool for fatigue failure mechanism in a steel component.

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