A One-Dimensional Cloud Model with Trimodal Convective Outflow

2009 ◽  
Vol 22 (23) ◽  
pp. 6437-6455 ◽  
Author(s):  
Ian Folkins
Keyword(s):  
Relative Humidity ◽  
Cloud Model ◽  
Lower Troposphere ◽  
Lapse Rate ◽  
Tropical Atmosphere ◽  
One Dimensional ◽  
Convective Clouds ◽  
Convective Scale ◽  
The Stability ◽  
Melting Level

Abstract The author describes a one-dimensional cloud model designed to investigate the relationships between stratiform downdrafts, congestus outflow, stability, and relative humidity in the tropical lower troposphere. In the tropics, the climatological lapse rate varies with height below the melting level in a way that is inconsistent with the assumptions of either moist pseudoadiabatic or reversible adiabatic ascent. This anomalous variation is referred to as the melting-level stability anomaly (MLSA). It is argued that the MLSA is caused by a transition from static to dynamic downdrafts at the melting level. Above the melting level, evaporation of precipitation cools and moistens the tropical atmosphere but does not generate downdraft parcels with sufficient negative buoyancy to descend between model levels. Below the melting level, the evaporative cooling associated with stratiform precipitation is strong enough to overcome the stability of the atmosphere and generate a convective-scale circulation. The vertical descent within these downdrafts induces a compensatory ascent in the background atmosphere that changes the overall cooling-to-moistening downdraft ratio. The inclusion of this stratiform downdraft circulation brings the modeled lapse rate and relative humidity profiles into simultaneous agreement with observations. The transition from static to dynamic downdrafts is triggered, in the model, by imposed increases in the amount of rain falling outside clouds, in the out-of-cloud rain rate, and in the vertical coherence of the rain shafts. The destabilization of the lower tropical atmosphere triggered by the stratiform circulation affects the development of convective clouds. In particular, the melting-level stability anomaly increases detrainment near the melting level and gives rise to the congestus mode.

scholarly journals Height increase of the melting level stability anomaly in the tropics

2012 ◽  
Vol 12 (5) ◽  
pp. 11567-11594 ◽  
Author(s):  
I. Folkins
Keyword(s):  
Surface Temperature ◽  
Lower Troposphere ◽  
Lapse Rate ◽  
Free Air ◽  
Upward Displacement ◽  
Height Increase ◽  
Cumulus Congestus ◽  
The Stability ◽  
The Tropics ◽  
Melting Level

Abstract. In actively convecting regions of the tropics, the lower troposphere is significantly less stable than predicted by a moist pseudoadiabat. This anomalous variation in lapse rate occurs between the boundary layer inversion (~2 km) and the melting level (~5 km), and has been attributed to mesoscale downdrafts that develop below precipitating stratiform anvil clouds. We use an 11 yr record (1998–2008) from five Western Tropical Pacific radiosonde stations in the Stratospheric Processes and their Role in Climate (SPARC) archive, to determine the response of this stability anomaly to changes in monthly mean surface temperature. We find that the stability anomaly shifts upward when the surface temperature increases, by an amount roughly equal to the upward displacement of the melting level. It is likely that this change in lower tropospheric stability is associated with increases in the height of cumulus congestus clouds, in the vertical distance through which stratiform precipitation falls through cloud free air, and in the vertical wavelength of the stratiform heating mode.

scholarly journals The melting level stability anomaly in the tropics

2013 ◽  
Vol 13 (3) ◽  
pp. 1167-1176 ◽  
Author(s):  
I. Folkins
Keyword(s):  
Surface Temperature ◽  
Deep Convection ◽  
Temperature Response ◽  
Lower Troposphere ◽  
Local Maximum ◽  
Similar Response ◽  
Upward Displacement ◽  
The Stability ◽  
The Tropics ◽  
Melting Level

Abstract. On short timescales, the effect of deep convection on the tropical atmosphere is to heat the upper troposphere and cool the lower troposphere. This stratiform temperature response to deep convection gives rise to a local maximum in stability near the melting level. We use temperature measurements from five radiosonde stations in the Western Tropical Pacific, from the Stratospheric Processes and their Role in Climate (SPARC) archive, to examine the response of this mid-tropospheric stability maximum to changes in surface temperature. We find that the height of the stability maximum increases when the surface temperature increases, by an amount roughly equal to the upward displacement of the 0 °C melting level. Although this response was determined using monthly mean temperature anomalies from an 10 yr record (1999–2008), we use model results to show that a similar response should also be expected on longer timescales.

scholarly journals On the Numerical Simulation of HPDEs Using θ-Weighted Scheme and the Galerkin Method

Mathematics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 78
Author(s):  
Haifa Bin Jebreen ◽  
Fairouz Tchier
Keyword(s):  
Differential Equation ◽  
Galerkin Method ◽  
Linear Ordinary Differential Equation ◽  
Time Interval ◽  
Hyperbolic Partial Differential Equation ◽  
Time Step ◽  
Numerical Examples ◽  
One Dimensional ◽  
The Stability ◽  
The Galerkin Method

Herein, an efficient algorithm is proposed to solve a one-dimensional hyperbolic partial differential equation. To reach an approximate solution, we employ the θ-weighted scheme to discretize the time interval into a finite number of time steps. In each step, we have a linear ordinary differential equation. Applying the Galerkin method based on interpolating scaling functions, we can solve this ODE. Therefore, in each time step, the solution can be found as a continuous function. Stability, consistency, and convergence of the proposed method are investigated. Several numerical examples are devoted to show the accuracy and efficiency of the method and guarantee the validity of the stability, consistency, and convergence analysis.

scholarly journals Stability of a one-dimensional morphoelastic model for post-burn contraction

2021 ◽  
Vol 83 (3) ◽  
Author(s):  
Ginger Egberts ◽  
Fred Vermolen ◽  
Paul van Zuijlen
Keyword(s):  
Wound Healing ◽  
Residual Stresses ◽  
Truncation Error ◽  
Signaling Molecules ◽  
Discrete Problem ◽  
One Dimensional ◽  
Stability Constraint ◽  
Biological Interpretation ◽  
The Stability ◽  
The One

AbstractTo deal with permanent deformations and residual stresses, we consider a morphoelastic model for the scar formation as the result of wound healing after a skin trauma. Next to the mechanical components such as strain and displacements, the model accounts for biological constituents such as the concentration of signaling molecules, the cellular densities of fibroblasts and myofibroblasts, and the density of collagen. Here we present stability constraints for the one-dimensional counterpart of this morphoelastic model, for both the continuous and (semi-) discrete problem. We show that the truncation error between these eigenvalues associated with the continuous and semi-discrete problem is of order $${{\mathcal {O}}}(h^2)$$ O ( h 2 ) . Next we perform numerical validation to these constraints and provide a biological interpretation of the (in)stability. For the mechanical part of the model, the results show the components reach equilibria in a (non) monotonic way, depending on the value of the viscosity. The results show that the parameters of the chemical part of the model need to meet the stability constraint, depending on the decay rate of the signaling molecules, to avoid unrealistic results.

scholarly journals One-Dimensional Organic–Inorganic Material (C6H9N2)2BiCl5: From Synthesis to Structural, Spectroscopic, and Electronic Characterizations

2021 ◽  
Vol 22 (4) ◽  
pp. 2030
Author(s):  
Hela Ferjani ◽  
Hammouda Chebbi ◽  
Mohammed Fettouhi
Keyword(s):  
Hydrogen Bonding ◽  
Density Functional ◽  
Crystal Packing ◽  
Diffuse Reflectance Spectrum ◽  
Enrichment Ratio ◽  
One Dimensional ◽  
Organic Part ◽  
Fukui Indices ◽  
The Stability ◽  
The One

The new organic–inorganic compound (C6H9N2)2BiCl5 (I) has been grown by the solvent evaporation method. The one-dimensional (1D) structure of the allylimidazolium chlorobismuthate (I) has been determined by single crystal X-ray diffraction. It crystallizes in the centrosymmetric space group C2/c and consists of 1-allylimidazolium cations and (1D) chains of the anion BiCl52−, built up of corner-sharing [BiCl63−] octahedra which are interconnected by means of hydrogen bonding contacts N/C–H⋯Cl. The intermolecular interactions were quantified using Hirshfeld surface analysis and the enrichment ratio established that the most important role in the stability of the crystal structure was provided by hydrogen bonding and H···H interactions. The highest value of E was calculated for the contact N⋯C (6.87) followed by C⋯C (2.85) and Bi⋯Cl (2.43). These contacts were favored and made the main contribution to the crystal packing. The vibrational modes were identified and assigned by infrared and Raman spectroscopy. The optical band gap (Eg = 3.26 eV) was calculated from the diffuse reflectance spectrum and showed that we can consider the material as a semiconductor. The density functional theory (DFT) has been used to determine the calculated gap, which was about 3.73 eV, and to explain the electronic structure of the title compound, its optical properties, and the stability of the organic part by the calculation of HOMO and LUMO energy and the Fukui indices.

scholarly journals Basic Diagnosis and Prediction of Persistent Contrail Occurrence Using High-Resolution Numerical Weather Analyses/Forecasts and Logistic Regression. Part II: Evaluation of Sample Models

2009 ◽  
Vol 48 (9) ◽  
pp. 1790-1802 ◽  
Author(s):  
David P. Duda ◽  
Patrick Minnis
Keyword(s):  
Relative Humidity ◽  
Wind Direction ◽  
Meteorological Data ◽  
Logistic Models ◽  
Satellite Observations ◽  
Lapse Rate ◽  
Prediction System ◽  
Advanced Regional Prediction System ◽  
Regional Prediction ◽  
Surface Models

Abstract A probabilistic forecast to accurately predict contrail formation over the conterminous United States (CONUS) is created by using meteorological data based on hourly meteorological analyses from the Advanced Regional Prediction System (ARPS) and the Rapid Update Cycle (RUC) combined with surface and satellite observations of contrails. Two groups of logistic models were created. The first group of models (SURFACE models) is based on surface-based contrail observations supplemented with satellite observations of contrail occurrence. The most common predictors selected for the SURFACE models tend to be related to temperature, relative humidity, and wind direction when the models are generated using RUC or ARPS analyses. The second group of models (OUTBREAK models) is derived from a selected subgroup of satellite-based observations of widespread persistent contrails. The most common predictors for the OUTBREAK models tend to be wind direction, atmospheric lapse rate, temperature, relative humidity, and the product of temperature and humidity.

scholarly journals Thermal structure of intense convective clouds derived from GPS radio occultations

2012 ◽  
Vol 12 (12) ◽  
pp. 5309-5318 ◽  
Author(s):  
R. Biondi ◽  
W. J. Randel ◽  
S.-P. Ho ◽  
T. Neubert ◽  
S. Syndergaard
Keyword(s):  
Thermal Structure ◽  
Deep Convection ◽  
Lapse Rate ◽  
Orthogonal Polarization ◽  
Cold Temperatures ◽  
Temperature Lapse Rate ◽  
Convective Systems ◽  
Convective Clouds ◽  
Strong Inversion ◽  
Cloud Tops

Abstract. Thermal structure associated with deep convective clouds is investigated using Global Positioning System (GPS) radio occultation measurements. GPS data are insensitive to the presence of clouds, and provide high vertical resolution and high accuracy measurements to identify associated temperature behavior. Deep convective systems are identified using International Satellite Cloud Climatology Project (ISCCP) satellite data, and cloud tops are accurately measured using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIPSO) lidar observations; we focus on 53 cases of near-coincident GPS occultations with CALIPSO profiles over deep convection. Results show a sharp spike in GPS bending angle highly correlated to the top of the clouds, corresponding to anomalously cold temperatures within the clouds. Above the clouds the temperatures return to background conditions, and there is a strong inversion at cloud top. For cloud tops below 14 km, the temperature lapse rate within the cloud often approaches a moist adiabat, consistent with rapid undiluted ascent within the convective systems.

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