scholarly journals Role of sublimation and riming in the precipitation distribution in the Kananaskis Valley, Alberta, Canada

2019 ◽  
Vol 23 (10) ◽  
pp. 4097-4111
Author(s):  
Émilie Poirier ◽  
Julie M. Thériault ◽  
Maud Leriche
Keyword(s):  
Emergency Services ◽  
Water Cycle ◽  
Vertical Shear ◽  
Atmospheric Conditions ◽  
Phase Precipitation ◽  
Surface Evolution ◽  
Temperature Changes ◽  
Surface Precipitation ◽  
Ice Phase

Abstract. The phase of precipitation and its distribution at the surface can affect water resources and the regional water cycle of a region. A field project was held in March–April 2015 on the eastern slope of the Canadian Rockies to document precipitation characteristics and associated atmospheric conditions. During the project, 60 % of the particles documented were rimed in relatively warm and dry conditions. Rain–snow transitions also occurred aloft and at the surface in sub-saturated conditions. Ice-phase precipitation falling through a saturated atmospheric layer with temperatures > 0 ∘C will start melting. In contrast, if the melting layer is sub-saturated, the ice-phase precipitation undergoes sublimation, which increases the depth of the rain–snow transition. In this context, this study investigates the role of sublimation and riming in precipitation intensity and type reaching the surface in the Kananaskis Valley, Alberta, during March–April 2015. To address this, a set of numerical simulations of an event of mixed precipitation observed at the surface was conducted. This event on 31 March 2015 was documented with a set of devices at the main observation site (Kananaskis Emergency Services, KES), including a precipitation gauge, disdrometer, and micro rain radar. Sensitivity experiments were performed to assess the impacts of temperature changes from sublimation and the role of the production of graupel (riming) aloft in the surface precipitation evolution. A warmer environment associated with no temperature changes from sublimation leads to a peak in the intensity of graupel at the surface. When the formation of graupel is not considered, the maximum snowfall rate occurred at later times. Results suggest that unrimed snow reaching the surface is formed on the western flank and is advected eastward. In contrast, graupel would form aloft in the Kananaskis Valley. The cooling from sublimation and melting by rimed particles increases the vertical shear near KES. Overall, this study illustrated that the presence of graupel influenced the surface evolution of precipitation type in the valley due to the horizontal transport of precipitation particles.

scholarly journals Role of sublimation and riming on the precipitation distribution in the Kananaskis Valley, Alberta, Canada

2019 ◽  
Author(s):  
Émilie Poirier ◽  
Julie M. Thériault ◽  
Maud Leriche
Keyword(s):  
Emergency Services ◽  
Water Cycle ◽  
Vertical Shear ◽  
Atmospheric Conditions ◽  
Surface Evolution ◽  
Temperature Changes ◽  
Surface Precipitation ◽  
Solid Precipitation ◽  
Precipitation Gauge

Abstract. The phase of precipitation and its distribution at the surface can affect water resources and the regional water cycle of a region. A field project was held in March–April 2015 on the eastern slope of the Canadian Rockies to document precipitation characteristics and associated atmospheric conditions. During the project, 60 % of the particles documented were rimed, in relatively warm and dry conditions. Rain-snow transitions also occurred aloft and at the surface in sub-saturated conditions. Solid precipitation falling through a saturated atmospheric layer with temperatures > 0 °C will start melting. In contrast, if the melting layer is sub-saturated, the solid precipitation undergoes sublimation, which increases the depth of the rain-snow transition. In this context, this study investigates the role of sublimation and riming on precipitation intensity and type reaching the surface in the Kananaskis Valley, Alberta, where the field campaign took place during March–April 2015. To address this, a set of numerical simulations of an event of mixed precipitation observed at the surface was conducted. This event on 31 March 2015, was documented with a set of devices at the main observation site (Kananaskis Emergency Services, KES) including a precipitation gauge, disdrometer, and micro rain radar. Sensitivity experiments were performed to assess the impacts of temperature changes from sublimation and the role of the production of snow pellets (riming) aloft on the surface precipitation evolution. A warmer environment associated with no temperature changes from sublimation leads to a peak in the intensity of snow pellets at the surface. When the formation of snow pellets is not considered, the maximum snowfall rate occurred at later times. Results suggest that unrimed snow reaching the surface is formed on the western flank and is advected eastward. In contrast, snow pellets would form aloft in the Kananaskis Valley. The cooling from sublimation and melting by rime particles increases the vertical shear near KES. Overall, this study illustrated that the presence of snow pellets influenced the surface evolution of precipitation type in the valley due to the horizontal transport of precipitation particles.

scholarly journals Enhancement of ice-phase precipitation caused by thermal forcing produces ghost echoes over the Tibetan Plateau

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yilun Chen ◽  
Aoqi Zhang ◽  
Shumin Chen ◽  
Chaoyong Tu ◽  
Weibiao Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Heavy Precipitation ◽  
Dynamic Factor ◽  
The Tibetan Plateau ◽  
Dual Frequency ◽  
Phase Precipitation ◽  
Thermal Forcing ◽  
Near Surface ◽  
Surface Precipitation ◽  
Ice Phase

AbstractWhether tall storms produce heavy precipitation is currently a controversial topic. Here, we used seven years of observations from the dual-frequency precipitation radar and found that there is a rare but unique vertical precipitation structure over the Tibetan Plateau. The radar echo peaks above the freezing height, which we refer to as a “ghost echo”. The existence of a ghost echo increases the echo-top height but suppresses the increase in droplet size below it, and therefore weakens the near-surface precipitation. Compared with normal echoes, ghost echoes appear more often in the afternoon. The potentially unstable environment produced by thermal forcing is the main cause of ghost echoes, rather than the dynamic factor of wind shear. The ghost echo, which is essentially a mechanism of ice-phase precipitation enhancement, represents a type of tall but weak precipitation. Its existence adds to our current perception of the nature of precipitation.

scholarly journals Wrist fracture management and the role of surgical care practitioner through the patient’s journey

2021 ◽  
pp. 175045892097607
Author(s):  
Rojas Moya Desiree ◽  
Russell Kabir
Keyword(s):  
Emergency Services ◽  
Surgical Care ◽  
Wrist Fracture ◽  
Junior Doctors ◽  
Examination Technique ◽  
Legal Implications ◽  
Fracture Management ◽  
Surgical Options

The presentation of this case study involves an exploration of the patient's journey in detail after having a traumatic wrist fracture, which is recognised as one of the most common fractures encountered daily in emergency services by junior doctors and practitioners. However, this article not only analyses the medical guidance for this type of case, but also the importance of the surgical care practitioner role in trauma and orthopaedics. All practitioners attending patients in emergency services are required to develop a good knowledge of anatomy, physiology, patient’s examination technique, classifications and consequently being aware of the possible surgical options for treatment of the fracture. They will also need to fully understand the legal implications of consent to ensure safe practice.

Ice-Phase Precipitation

2017 ◽  
Vol 58 ◽  
pp. 6.1-6.36 ◽  
Author(s):  
I. Gultepe ◽  
A. J. Heymsfield ◽  
P. R. Field ◽  
D. Axisa
Keyword(s):  
Collection Efficiency ◽  
Numerical Models ◽  
Mass Density ◽  
Three Dimensional ◽  
Phase Precipitation ◽  
Microphysical Parameters ◽  
Mass Size ◽  
Ice Water ◽  
Ice Phase

AbstractIce-phase precipitation occurs at Earth’s surface and may include various types of pristine crystals, rimed crystals, freezing droplets, secondary crystals, aggregates, graupel, hail, or combinations of any of these. Formation of ice-phase precipitation is directly related to environmental and cloud meteorological parameters that include available moisture, temperature, and three-dimensional wind speed and turbulence, as well as processes related to nucleation, cooling rate, and microphysics. Cloud microphysical parameters in the numerical models are resolved based on various processes such as nucleation, mixing, collision and coalescence, accretion, riming, secondary ice particle generation, turbulence, and cooling processes. These processes are usually parameterized based on assumed particle size distributions and ice crystal microphysical parameters such as mass, size, and number and mass density. Microphysical algorithms in the numerical models are developed based on their need for applications. Observations of ice-phase precipitation are performed using in situ and remote sensing platforms, including radars and satellite-based systems. Because of the low density of snow particles with small ice water content, their measurements and predictions at the surface can include large uncertainties. Wind and turbulence affecting collection efficiency of the sensors, calibration issues, and sensitivity of ground-based in situ observations of snow are important challenges to assessing the snow precipitation. This chapter’s goals are to provide an overview for accurately measuring and predicting ice-phase precipitation. The processes within and below cloud that affect falling snow, as well as the known sources of error that affect understanding and prediction of these processes, are discussed.

scholarly journals Evidence for the role of organics in aerosol particle formation under atmospheric conditions

2010 ◽  
Vol 107 (15) ◽  
pp. 6646-6651 ◽  
Author(s):  
A. Metzger ◽  
B. Verheggen ◽  
J. Dommen ◽  
J. Duplissy ◽  
A. S. H. Prevot ◽  
...  
Keyword(s):  
Aerosol Particle ◽  
Particle Formation ◽  
Atmospheric Conditions

Putative antihyperpyretic factor induced by LPS in spleen of guinea pigs

2005 ◽  
Vol 289 (3) ◽  
pp. R680-R687 ◽  
Author(s):  
Carlos Feleder ◽  
Vit Perlik ◽  
Ying Tang ◽  
Clark M. Blatteis
Keyword(s):  
Kupffer Cells ◽  
Guinea Pigs ◽  
Collateral Circulation ◽  
Splenic Vein ◽  
Inhibitory Factor ◽  
Febrile Response ◽  
Temperature Changes ◽  
The Core ◽  
Temporally Correlated

We reported previously that the onset of LPS-induced fever, irrespective of its route of administration, is temporally correlated with the appearance of LPS in the liver and that splenectomy significantly increases both the febrile response to LPS and the uptake of LPS by Kupffer cells (KC). To further evaluate the role of the spleen in LPS fever production, we ligated the splenic vein and, 7 and 30 days later, monitored the core temperature changes over 6 h after intraperitoneal (ip) injection of LPS (2 μg/kg). Both the febrile response and the uptake of LPS by KC were significantly augmented. Like splenectomy, splenic vein ligation (SVL) increased the febrile response and LPS uptake by KC until the collateral circulation developed, suggesting that the spleen may normally contribute an inhibitory factor that limits KC uptake of LPS and thus affects the febrile response. Subsequently, to verify the presence of this factor, we prepared splenic extracts from guinea pigs pretreated with LPS (8 μg/kg ip) or pyrogen-free saline, homogenized and ultrafiltered them, and injected them intravenously into splenectomized (Splex) guinea pigs pretreated with LPS (8 μg/kg ip). The results confirmed our presumption that the splenic extract from LPS-treated guinea pigs inhibits the exaggerated febrile response and the LPS uptake by the liver of Splex guinea pigs, indicating the presence of a putative splenic inhibitory factor, confirming the participation of the spleen in LPS-induced fever, and suggesting the existence of a novel antihyperpyretic mechanism. Preliminary data indicate that this factor is a lipid.

Role of ion transfer processes in acid-base regulation with temperature changes in fish

1984 ◽  
Vol 246 (4) ◽  
pp. R441-R451 ◽  
Author(s):  
N. Heisler
Keyword(s):  
Ion Transfer ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Fish Tissues ◽  
Model Calculations ◽  
Temperature Changes ◽  
Transfer Processes ◽  
Transfer Mechanisms

The contributions of transmembrane and transepithelial ion transfer processes and of nonbicarbonate buffering to the in vivo acid-base regulation have been evaluated. Model calculations were performed utilizing experimental data on transepithelial transfer of ions relevant for the acid-base regulation, the intracellular buffering properties of fish tissues, and the behavior of intracellular and extracellular pH and bicarbonate concentration with changes of temperature. The results of these studies indicate that the changes in the pK values of physiological nonbicarbonate buffers with changes in temperature support the adjustment of pH to lower values with rising temperature; however, transmembrane and transepithelial ion transfer mechanisms determine the acid-base regulation of intracellular and extracellular compartments.

scholarly journals Interannual Variability of Tropical Cyclones in the Australian Region: Role of Large-Scale Environment

2008 ◽  
Vol 21 (5) ◽  
pp. 1083-1103 ◽  
Author(s):  
Hamish A. Ramsay ◽  
Lance M. Leslie ◽  
Peter J. Lamb ◽  
Michael B. Richman ◽  
Mark Leplastrier
Keyword(s):  
Interannual Variability ◽  
Large Scale ◽  
Vertical Wind Shear ◽  
Principal Component ◽  
Relative Vorticity ◽  
Vertical Shear ◽  
Scale Parameters ◽  
Australian Region ◽  
Sst Variability

Abstract This study investigates the role of large-scale environmental factors, notably sea surface temperature (SST), low-level relative vorticity, and deep-tropospheric vertical wind shear, in the interannual variability of November–April tropical cyclone (TC) activity in the Australian region. Extensive correlation analyses were carried out between TC frequency and intensity and the aforementioned large-scale parameters, using TC data for 1970–2006 from the official Australian TC dataset. Large correlations were found between the seasonal number of TCs and SST in the Niño-3.4 and Niño-4 regions. These correlations were greatest (−0.73) during August–October, immediately preceding the Australian TC season. The correlations remain almost unchanged for the July–September period and therefore can be viewed as potential seasonal predictors of the forthcoming TC season. In contrast, only weak correlations (<+0.37) were found with the local SST in the region north of Australia where many TCs originate; these were reduced almost to zero when the ENSO component of the SST was removed by partial correlation analysis. The annual frequency of TCs was found to be strongly correlated with 850-hPa relative vorticity and vertical shear of the zonal wind over the main genesis areas of the Australian region. Furthermore, correlations between the Niño SST and these two atmospheric parameters exhibited a strong link between the Australian region and the Niño-3.4 SST. A principal component analysis of the SST dataset revealed two main modes of Pacific Ocean SST variability that match very closely with the basinwide patterns of correlations between SST and TC frequencies. Finally, it is shown that the correlations can be increased markedly (e.g., from −0.73 to −0.80 for the August–October period) by a weighted combination of SST time series from weakly correlated regions.

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