scholarly journals Drivers of ASCAT C band backscatter variability in the dry snow zone of Antarctica

2016 ◽  
Vol 62 (231) ◽  
pp. 170-184 ◽  
Author(s):  
ALEXANDER D. FRASER ◽  
MELISSA A. NIGRO ◽  
STEFAN R. M. LIGTENBERG ◽  
BENOIT LEGRESY ◽  
MANA INOUE ◽  
...  
Keyword(s):  
Wind Speed ◽  
Surface Temperature ◽  
Incidence Angle ◽  
Climatic Forcing ◽  
Factors Influencing ◽  
Angle Diversity ◽  
Anisotropy Parameters ◽  
Long Timescales ◽  
Dry Snow Zone

ABSTRACTC band backscatter parameters contain information about the upper snowpack/firn in the dry snow zone. The wide incidence angle diversity of the Advanced Scatterometer (ASCAT) gives unprecedented characterisation of backscatter anisotropy, revealing the backscatter response to climatic forcing. TheA(isotropic component) andM2(bi-sinusoidal azimuth anisotropy) parameters are investigated here, in conjunction with data from atmospheric and snowpack models, to identify the backscatter response to surface forcing parameters (wind speed and persistence, precipitation, surface temperature, density and grain size). The long-term meanAparameter is successfully recreated with a regression using these drivers, indicating strong links between theAparameter and precipitation on long timescales. While the ASCAT time series is too short to determine which factors drive observed trends, factors influencing the seasonal and short timescale variability are revealed. On these timescales,Astrongly responds to the propagation of surface temperature cycles/anomalies downward through the firn, via direct modulation of the dielectric constant. The influence of precipitation onAis small at shorter timescales. TheM2parameter is controlled by wind speed and persistence, through modification of monodirectionally-aligned surface roughness. This variability indicates that throughout much of coastal Antarctica, a microwave ‘snapshot’ is generally not representative of longer-term conditions.

FACTORS INFLUENCING THE DETERMINATION OF MAXIMUM SURFACE TEMPERATURE FOR EXPLOSION-PROOF LUMINAIRES

2017 ◽  
Vol 16 (6) ◽  
pp. 1309-1316 ◽  
Author(s):  
Lucian Moldovan ◽  
Sorin Burian ◽  
Mihai Magyari ◽  
Marius Darie ◽  
Dragos Fotau
Keyword(s):  
Surface Temperature ◽  
Maximum Surface ◽  
Factors Influencing ◽  
Maximum Surface Temperature

scholarly journals Study of factors influencing the encrustation of indwelling catheters: prospective case series

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Sanket Kalpande ◽  
P. R. Saravanan ◽  
K. Saravanan
Keyword(s):  
Case Series ◽  
Definitive Treatment ◽  
Physically Active ◽  
Indwelling Catheters ◽  
Factors Influencing ◽  
Culture Sensitivity ◽  
Calcium Phosphorus ◽  
Prospective Case Series ◽  
Active Patients

Abstract Background Long-term catheterisation is frequently necessary for patients with retention of urine or intractable incontinence who are unfit for definitive treatment or being evaluated for definitive treatment. In this study, the important factors influencing the encrustation of indwelling catheters are analysed. Methods A total of 52 patients on catheter drainage for a period ranging from 1 month to 1 year were taken in the study. Patients reported either for problems like catheter block or routine changing of catheter. The catheters were removed, and encrustation was subjected to chemical analysis. Urine was examined for pH, specific gravity, culture sensitivity and appearance. Blood samples were taken for estimation of calcium, phosphorus and uric acid. Results Out of 52 patients, 28 with urea splitting and 15 with non-urea splitting had positive urine culture (43 out of 52). Amongst 28, 27 (96%) had encrustation compared to 10 (50%) out of 15 with non-urea splitting bacteria (p value < .05). Amongst 24 patients having pH > 6, 22 (92%) had encrustation (p value < .05). The encrustation was found to be more common in bedridden patients (91%) when compared to physically active patients (54%) (p value < .05). The encrustation was more common in patients having single catheter for more than 15 days (86%) when compared to patients having catheter for shorter period (43%) (p value < .05). Conclusion This study showed definitive influence of the following factors in encrustation formation: infection with urea splitting organism, alkaline pH, physical activity of patient and duration of keeping a particular catheter.

scholarly journals Analysis of Hydrothermal Systems Beneath Tayukeng through Long-Term Geochemical Signals of Hydrothermal Fluids in Tatun Volcano Group, Taiwan

2021 ◽  
Vol 18 (14) ◽  
pp. 7411
Author(s):  
Hsin-Fu Yeh ◽  
Hung-Hsiang Hsu
Keyword(s):  
Surface Temperature ◽  
Hydrothermal System ◽  
Hydrothermal Fluid ◽  
Thermal Water ◽  
Hydrothermal Systems ◽  
Hydrothermal Fluids ◽  
Geochemical Variations ◽  
Northern Taiwan

The Tatun Volcano Group (TVG) is located in northern Taiwan and consists of many springs and fumaroles. The Tayukeng (TYK) area is the most active fumarole site in the TVG. In this study, we analyzed the long-term geochemical variations of hydrothermal fluids and proposed a mechanism responsible for the variation in TYK. There are two different aquifers beneath the TYK area: a shallow SO42−-rich aquifer and a deeper aquifer rich in Cl−. TYK thermal water was mainly supplied by the shallow SO42−-rich aquifer; therefore, the thermal water showed high SO42− concentrations. After 2015, the inflow of deep thermal water increased, causing the Cl− concentrations of the TYK to increase. Notably, the inferred reservoir temperatures based on quartz geothermometry increased; however, the surface temperature of the spring decreased. We inferred that the enthalpy was lost during transportation to the surface. Therefore, the surface temperature of the spring does not increase with an increased inflow of deep hydrothermal fluid. The results can serve as a reference for understanding the complex evolution of the magma-hydrothermal system in the TVG.

scholarly journals Atmospheric Thermal and Dynamic Vertical Structures of Summer Hourly Precipitation in Jiulong of the Tibetan Plateau

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 505
Author(s):  
Yonglan Tang ◽  
Guirong Xu ◽  
Rong Wan ◽  
Xiaofang Wang ◽  
Junchao Wang ◽  
...  
Keyword(s):  
Wind Speed ◽  
Tibetan Plateau ◽  
Precipitation Amount ◽  
Summer Precipitation ◽  
The Tibetan Plateau ◽  
Hourly Precipitation ◽  
Air Convection ◽  
Precipitation Variation ◽  
Long Term Observation

It is an important to study atmospheric thermal and dynamic vertical structures over the Tibetan Plateau (TP) and their impact on precipitation by using long-term observation at representative stations. This study exhibits the observational facts of summer precipitation variation on subdiurnal scale and its atmospheric thermal and dynamic vertical structures over the TP with hourly precipitation and intensive soundings in Jiulong during 2013–2020. It is found that precipitation amount and frequency are low in the daytime and high in the nighttime, and hourly precipitation greater than 1 mm mostly occurs at nighttime. Weak precipitation during the daytime may be caused by air advection, and strong precipitation at nighttime may be closely related with air convection. Both humidity and wind speed profiles show obvious fluctuation when precipitation occurs, and the greater the precipitation intensity, the larger the fluctuation. Moreover, the fluctuation of wind speed is small in the morning, large at noon and largest at night, presenting a similar diurnal cycle to that of convective activity over the TP, which is conductive to nighttime precipitation. Additionally, the inverse layer is accompanied by the inverse humidity layer, and wind speed presents multi-peaks distribution in its vertical structure. Both of these are closely related with the underlying surface and topography of Jiulong. More studies on physical mechanism and numerical simulation are necessary for better understanding the atmospheric phenomenon over the TP.

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