scholarly journals Influence of Atmosphere Near-Surface Layer Properties on Development of Cloud Convection

Atmosphere ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 131 ◽  
Author(s):  
Magomet Abshaev ◽  
Robert Zakinyan ◽  
Ali Abshaev ◽  
Qasim Al-Owaidi ◽  
Ludmila Kulgina ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Surface Layer ◽  
Water Vapor ◽  
Mass Fraction ◽  
Dew Point ◽  
Two Dimensional ◽  
Near Surface ◽  
Air Heating ◽  
Vapor Mass ◽  
Stimulation Of

A two-dimensional mathematical model of moist air convection in the sub-cloud and cloud layers is proposed. A theoretical analysis of the influence of near ground atmospheric parameters on the development of sub-cloud and cloud convection is provided, and the criteria of convection development are considered. As a rule, this relationship is parameterized in general circulation, regional or mesoscale models of the atmosphere. Therefore, achieving a more complete and correct understanding of this relationship can lead to an improvement in the accuracy of weather forecasts. The mathematical model describes the system of the equations of motion, heat conductivity and the continuity equations for a two-dimensional vertical plane. The approximate analytical solution of the system of equations is obtained. Expressions for the estimation of the convection height and height of maximum velocity are derived for vertical and horizontal components of updraft wind and for vertical distribution of temperature. From the expressions obtained, the criterion of sub-cloud convection development is derived. The expressions for the convection parameters at a condensation level have also been formulated, from which the criterion of cloud development through convection is derived. It is established that the development of cloud convection depends on absolute values of the dew point deficit in a near-surface layer and, in a greater degree, on vertical gradients of water vapor mass fraction. It is shown that at certain critical values of a vertical gradient of water vapor mass fraction “explosive convective growth” is observed. The application of the obtained results to artificial stimulation of convection by means of air heating in the near-ground atmosphere has shown that the success of such an application and the required air heating-up depend on: (i) the vertical temperature gradient; (ii) the vertical dew-point gradient; and (iii) the value of the dew point deficit in the near-ground layer. The analysis performed has shown the possibility of successful stimulation of artificial convection under specific favorable atmospheric conditions.

Precipitation scaling in the tropics with a convection-permitting model

2020 ◽  
Author(s):  
Daniel Argüeso ◽  
Alejandro Di Luca ◽  
Nicolas Jourdain ◽  
Romualdo Romero ◽  
Victor Homar
Keyword(s):  
Water Vapor ◽  
Large Scale ◽  
Potential Temperature ◽  
Lower Troposphere ◽  
Dew Point ◽  
Precipitation Extremes ◽  
Maritime Continent ◽  
Near Surface ◽  
Intense Precipitation ◽  
Precipitation Events

<p>The Maritime Continent is a major convective area and precipitation processes in the region pose great challenges to atmospheric models. A combination of large-scale drivers, such as the Madden-Julian Oscillation and ENSO, and fine-scale processes, such as orographically-forced precipitation, land-sea circulations and tropical convection, governs rainfall in the Maritime Continent. The use of convection-permitting models in the region has shown improved performance in the simulation of precipitation characteristics that are key for the region (i.e. diurnal cycle).</p><p>Most of the rainfall occurring over land is concentrated in the late afternoon and precipitation extremes often occur over short periods of time. The availability of water vapor in the lower troposphere and the high water-holding capacity of a warm atmosphere favors very intense precipitation events, according to the Clausius-Clapeyron relationship. In a warming climate, a full understanding of the so-called precipitation scaling with temperature is thus crucial. However, this potential generally requires the atmosphere be saturated and convection be initiated to become effective. Using a regional climate model operating at convection-permitting scales over 3 consecutive wet seasons, we investigate the response of intense precipitation to temperature.</p><p>In this presentation, we examine different approaches to relate precipitation extremes to near-surface temperature and dew-point temperature. We show that the relationship breaks at certain thresholds that are relatively uniform across islands. The region is well supplied with water vapor and the break is not explained by a deficit in water vapor, unlike previously proposed for other water-limited regions. We identify possible reasons for this behavior, such as the lack of environmental conditions that trigger convection. In this context, we explore the sensitivity of the modelling system to the convection representation (explicit vs. parameterized) and discuss the implications for future changes in intense precipitation events. Finally, we put forward the use of specific variables, such as temperature and equivalent potential temperature integrated in the vertical. These variables not only are coherent with the CC equation but also acknowledge the different warming rates near the surface and at higher tropospheric levels, where precipitating processes actually occur.</p>

Development of a mathematical model for predicting water vapor mass generated in micro-explosion

Energy ◽  
2011 ◽  
Vol 36 (7) ◽  
pp. 4089-4096 ◽  
Author(s):  
Hirotatsu Watanabe ◽  
Yoshiyuki Suzuki ◽  
Takuji Harada ◽  
Hideyuki Aoki ◽  
Takatoshi Miura
Keyword(s):  
Mathematical Model ◽  
Water Vapor ◽  
Vapor Mass

The Influence of Smoke From Forest Fires on the Meteorological and Electrical Characteristics of the Atmosphere

2020 ◽  
pp. 322-344
Author(s):  
Petr Mikhailovich Nagorskiy ◽  
Mikhail Vsevolodovich Kabanov ◽  
Konstantin Nikolaevich Pustovalov
Keyword(s):  
Surface Layer ◽  
Water Vapor ◽  
Forest Fires ◽  
Western Siberia ◽  
Moisture Transfer ◽  
Diurnal Variations ◽  
Volume Charge ◽  
Homogeneous Surface ◽  
Near Surface ◽  
The Impact

The impact of smoke from forest fires in western Siberia on meteorological, atmospheric electric, and aerological variables has been analyzed. The anomalous distribution of water vapor in the atmosphere associated with the peculiarities of the evaporation regime and the absence of advective moisture transfer over the southern regions of Western Siberia during the fires. With an increase in the height of the homogeneous surface smoke layer with an unchanged aerosol optical thickness, the cooling of the earth's surface and heating of the atmosphere was weakened. The smoke plume spreads predominantly in the middle of the troposphere, creating aerosol layers elevated above the ground, the lower part of which had a negative volume charge. The effect of diurnal variations in the electrical field in the near-surface layer, differs from the known similar effects.

scholarly journals ESTIMATION OF THE CHANGE FROME HEIGHT OF THE VERTICAL AIR FLOW IN THE SURFACE LAYER OF THE ATMOSPHERE FOR A REGIME CLOSE TO THE ‘PURE CONVECTION’ REGIME

2020 ◽  
Vol 2 (32(59)) ◽  
pp. 13-17
Author(s):  
B. Kantsyrev
Keyword(s):  
Surface Layer ◽  
Water Vapor ◽  
Air Temperature ◽  
Mass Fraction ◽  
Continuity Equation ◽  
Asymptotic Form ◽  
Universal Functions ◽  
Physical Processes ◽  
Convection Regime ◽  
One Dimensional

The purpose of this work is to analyze and concretize the asymptotic form of writing the continuity equation [3] for modeling thermo-physical processes in the surface layer of the atmosphere. In this case, the solution of the system of spatially one-dimensional equations of conservation laws for vertical dependences of air temperature and mass fraction of water vapor can be obtained in the future by using the calculated empirical dependences for the coefficient of turbulent exchange, based on the Monin-Obukhov “universal functions” approach.

Two Dimensional Unsteady State Mathematical Model for dispersion of Chlorine in Water in a Channel

2011 ◽  
Vol 3 (8) ◽  
pp. 503-505
Author(s):  
Jaipal Jaipal ◽  
◽  
Rakesh Chandra Bhadula ◽  
V. N Kala V. N Kala
Keyword(s):  
Mathematical Model ◽  
Two Dimensional ◽  
Unsteady State

Recombination Characteristics of Single-Crystalline Silicon Wafers with a Damaged Near-Surface Layer

2013 ◽  
Vol 58 (2) ◽  
pp. 142-150 ◽  
Author(s):  
A.V. Sachenko ◽  
◽  
V.P. Kostylev ◽  
V.G. Litovchenko ◽  
V.G. Popov ◽  
...  
Keyword(s):  
Surface Layer ◽  
Crystalline Silicon ◽  
Silicon Wafers ◽  
Single Crystalline Silicon ◽  
Near Surface ◽  
Single Crystalline

scholarly journals Role of the heart in blood pressure lowering during chronic baroreflex activation: insight from an in silico analysis

2018 ◽  
Vol 315 (5) ◽  
pp. H1368-H1382 ◽  
Author(s):  
John S. Clemmer ◽  
W. Andrew Pruett ◽  
Robert L. Hester ◽  
Radu Iliescu ◽  
Thomas E. Lohmeier
Keyword(s):  
Blood Pressure ◽  
Mathematical Model ◽  
Renal Denervation ◽  
Sympathetic Nerve Activity ◽  
Blood Pressure Lowering ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Pressure Lowering ◽  
Renal Sympathetic ◽  
Stimulation Of

Electrical stimulation of the baroreflex chronically suppresses sympathetic activity and arterial pressure and is currently being evaluated for the treatment of resistant hypertension. The antihypertensive effects of baroreflex activation are often attributed to renal sympathoinhibition. However, baroreflex activation also decreases heart rate, and robust blood pressure lowering occurs even after renal denervation. Because controlling renal sympathetic nerve activity (RSNA) and cardiac autonomic activity cannot be achieved experimentally, we used an established mathematical model of human physiology (HumMod) to provide mechanistic insights into their relative and combined contributions to the cardiovascular responses during baroreflex activation. Three-week responses to baroreflex activation closely mimicked experimental observations in dogs including decreases in blood pressure, heart rate, and plasma norepinephrine and increases in plasma atrial natriuretic peptide (ANP), providing validation of the model. Simulations showed that baroreflex-induced alterations in cardiac sympathetic and parasympathetic activity lead to a sustained depression of cardiac function and increased secretion of ANP. Increased ANP and suppression of RSNA both enhanced renal excretory function and accounted for most of the chronic blood pressure lowering during baroreflex activation. However, when suppression of RSNA was blocked, the blood pressure response to baroreflex activation was not appreciably impaired due to inordinate fluid accumulation and further increases in atrial pressure and ANP secretion. These simulations provide a mechanistic understanding of experimental and clinical observations showing that baroreflex activation effectively lowers blood pressure in subjects with previous renal denervation. NEW & NOTEWORTHY Both experimental and clinical studies have shown that the presence of renal nerves is not an obligate requirement for sustained reductions in blood pressure during chronic electrical stimulation of the carotid baroreflex. Simulations using HumMod, a mathematical model of integrative human physiology, indicated that both increased secretion of atrial natriuretic peptide and suppressed renal sympathetic nerve activity play key roles in mediating long-term reductions in blood pressure during chronic baroreflex activation.

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