scholarly journals Análise de um Episódio de Baixa Térmica do Noroeste da Argentina

2021 ◽  
Vol 14 (1) ◽  
pp. 094
Author(s):  
Flávia Fernanda Azevedo Fagundes ◽  
Ivana Riêra Pereira Bastos ◽  
Michelle Simões Reboita ◽  
Gustavo Carlos Juan Escobar
Keyword(s):  
System Analysis ◽  
Global Analysis ◽  
Physical Structure ◽  
Relative Vorticity ◽  
Pressure System ◽  
Atmospheric Flow ◽  
Chaco Region ◽  
Forecasting System ◽  
Low Pressure System ◽  
Maximum Heating

Como há poucos estudos na literatura que descrevem a estrutura física das baixas térmicas no noroeste da Argentina (BNOA), isso torna-se o objetivo do presente trabalho. Para isso, são utilizados dados da Global Forecast System Analysis (GFSanl - Sistema de Previsão Global). O caso de BNOA em estudo teve gênese no dia 29 de outubro de 2009 às 0600 UTC e perdurou até o dia 03 de novembro às 1200 UTC. Sua estrutura vertical mostra máximo aquecimento e vorticidade relativa ciclônica entre a superfície e 750 hPa ao longo das longitudes de 70º a 65º W. Em níveis médios, durante todo o ciclo de vida da BNOA, predominou uma crista no escoamento atmosférico. A influência de sistemas transientes causa a desconfiguração da BNOA.   Analysis of an episode of Thermal Low of Northwest Argentina A B S T R A C TIn South America, there are two favorable places for the genesis of thermal lows (low pressure system with semi-stationary feature): Chaco region and the northwest of Argentina. Thermal lows developed in these regions receive their names. So, the purpose of this study is to describe the physical structure of thermal low occurred over the northwest of Argentina (TLNA). For this reason, data from the Global Analysis of the Forecasting System (GFSanl - Global Forecasting System) are used. TLNA had genesis on October 29, 2009 at 0600 UTC and decayed on November 03 at 1200 UTC. Its vertical structure shows the maximum heating and the cyclonic relative vorticity between the surface and 750 hPa along the longitudes 70º-65º W. At middle levels, throughout the TLNA's lifecycle, a ridge in the atmospheric flow predominated. The influence of the transient systems causes the deconfiguration of TLNA.Keywords: thermal low; northwestern Argentina; anticyclone; transient systems

scholarly journals The Synoptic Characteristics, Causes, and Mechanisms of Kahlaa Tornado in Iraq on 14th April 2016

2021 ◽  
Vol 18 (2(Suppl.)) ◽  
pp. 1038
Author(s):  
Thaer O. Roomi ◽  
Firas S. Basheer
Keyword(s):  
Convective Available Potential Energy ◽  
Weather Conditions ◽  
Relative Vorticity ◽  
Pressure System ◽  
The North ◽  
Damage Indices ◽  
Low Pressure System ◽  
Supercell Thunderstorm ◽  
Tornado Event ◽  
Cold Wind

In this study, an analysis of the synoptic characteristics, causes and mechanisms of Kahlaa tornado event was carried out. This tornado occurred on 10:30 UTC (1:30 pm Iraq Local Time) on 14 April 2016 to the north of Kahlaa town in Maysan governorate. We analyzed surface and upper charts, weather conditions, the damage indices, the dynamical features and the instability of the tornado. The analysis showed that there was a low pressure system which was an extension of the Monsoon low in addition to a supercell thunderstorm and a jet stream aloft. The cold trough and high relative vorticity at 500 hPa level, the humid warm wind blowing from the south and the dry cold wind from the north contributed to the initiation of the tornado. According to the damage amount, Kahlaa tornado can be classified as EF2 degree (considerable) on Enhanced Fujita scale. Three indices were calculated to estimate the instability of the tornado. The values of the convective available potential energy (CAPE), K-index, and lifted index were (≥2500 J/kg), (35.3 oC), and (-7), respectively. All these indices confirmed the instability required to form severe thunderstorm essential to tornado formation. Although the forecasting of tornadoes occurrence is difficult, there would be indications that may lead to expect of occurrence. These may include the availability of moisture, heat, and significant wind direction changes with altitude. However, the vital factors were the existence of high instability and a supercell thunderstorm.

Estimation of Design Parameters and Performance for a State-of-the-Art Turbofan

2021 ◽  
Author(s):  
Oliver Sjögren ◽  
Carlos Xisto ◽  
Tomas Grönstedt
Keyword(s):  
Performance Metrics ◽  
State Of The Art ◽  
Low Pressure ◽  
Performance Model ◽  
Cycle Performance ◽  
Civil Aviation ◽  
Design Parameters ◽  
Pressure System ◽  
Public Data ◽  
Low Pressure System

Abstract The aim of this study is to explore the possibility of matching a cycle performance model to public data on a state-of-the-art commercial aircraft engine (GEnx-1B). The study is focused on obtaining valuable information on figure of merits for the technology level of the low-pressure system and associated uncertainties. It is therefore directed more specifically towards the fan and low-pressure turbine efficiencies, the Mach number at the fan-face, the distribution of power between the core and the bypass stream as well as the fan pressure ratio. Available cycle performance data have been extracted from the engine emission databank provided by the International Civil Aviation Organization (ICAO), type certificate datasheets from the European Union Aviation Safety Agency (EASA) and the Federal Aviation Administration (FAA), as well as publicly available data from engine manufacturer. Uncertainties in the available source data are estimated and randomly sampled to generate inputs for a model matching procedure. The results show that fuel performance can be estimated with some degree of confidence. However, the study also indicates that a high degree of uncertainty is expected in the prediction of key low-pressure system performance metrics, when relying solely on publicly available data. This outcome highlights the importance of statistic-based methods as a support tool for the inverse design procedures. It also provides a better understanding on the limitations of conventional thermodynamic matching procedures, and the need to complement with methods that take into account conceptual design, cost and fuel burn.

Postural vascular response in human skin: passive and active reactions to alteration of transmural pressure

1993 ◽  
Vol 265 (3) ◽  
pp. H949-H958 ◽  
Author(s):  
H. Jepsen ◽  
P. Gaehtgens
Keyword(s):  
External Pressure ◽  
Passive Movement ◽  
Transmural Pressure ◽  
Vertical Position ◽  
Vascular Response ◽  
Pressure System ◽  
Arterial Blood ◽  
Actual Movement ◽  
Low Pressure System ◽  
Skin Blood Vessels

Laser-Doppler (LD) fluxmetry was performed in the palmar finger skin of healthy subjects to study the mechanisms contributing to the postural vascular response. Local transmural pressure in the skin blood vessels of the region studied was altered for 1 min in two experimental series either by passive movement of the arm to different vertical hand positions relative to heart level or by application of external pressure (-120-180 mmHg) to the finger. Heart and respiratory rate, arterial blood pressure, and LD flux in the contralateral finger (kept at heart level) were measured. The measurements suggest a compound reaction of local (myogenic) and systemic (neurogenic) mechanisms: the local regulatory component appears as a graded active vascular response elicited by passive vessel distension or compression. A systemic component, associated with a single deep inspiration, is frequently observed during the actual movement of the arm. In addition, prolonged holding of the test hand in a given vertical position also elicits a delayed vascular response in the control hand at heart level, which may be generated by volume receptors in the intrathoracic low-pressure system.

The effect of vasoactive drugs on the low-pressure system

1978 ◽  
Vol 73 (2) ◽  
pp. 220-229 ◽  
Author(s):  
K. Kirsch ◽  
A. Ameln ◽  
H. J. Wicke
Keyword(s):  
Low Pressure ◽  
Vasoactive Drugs ◽  
Pressure System ◽  
Low Pressure System

scholarly journals Synoptic perspectives on pollutant transport patterns observed by satellites over East Asia: Case studies with a conceptual model

2016 ◽  
Author(s):  
Hyun Cheol Kim ◽  
Soontae Kim ◽  
Seok-Woo Son ◽  
Pius Lee ◽  
Chun-Sil Jin ◽  
...  
Keyword(s):  
High Pressure ◽  
East Asia ◽  
Southern China ◽  
Low Pressure ◽  
Pressure System ◽  
Weather Patterns ◽  
High Pressure System ◽  
Synoptic Weather ◽  
Low Pressure System ◽  
Transport Patterns

Abstract. We demonstrate that daily pollutant transport patterns in East Asia are visible from satellite images when inspected with corresponding synoptic weather analyses. Transport pathways of air pollutants in East Asia are investigated using satellite observations, surface weather charts, and chemical-transport model simulations. It is found that during cool season (fall to spring), pollutant transports in East Asia are largely determined by synoptic weather patterns associated with high pressure system over southern China, which is extended from the Siberia High, and low pressure system over Manchuria, which is initiated by Altai-Sayan cyclogenesis. Based on the relative location and strength of these weather systems, three types of synoptic weather patterns that may contribute to pollutants transport in East Asia, especially in China and Korea, are identified: i.e., (1) a strengthening of the Siberian High and its southeastward propagation; (2) a high-pressure system over southern China followed by a frontal passage associated with a northern low-pressure system; and (3) a stagnant high-pressure system over southern China. For all three patterns, the high-pressure system in southern China is essential for the development of regional air pollution, while frontal activities associated with low-pressure system provide a forcing mechanism to transport those pollutants eastward or southeastward. Observed and simulated surface PM distributions show good agreement in both aerosol optical depth and NO2 column density further implying that anthropogenic emissions also contribute to regional events of high surface PM concentrations. It is argued that the quasi-periodic migration of synoptic weather systems in East Asia works as an efficient pump of pollutants; i.e., regional air pollutions developed under high-pressure systems are transported downstream by low-pressure systems.

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