scholarly journals The Influence of HCl on the Evaporation Rates of H<sub>2</sub>O over Water Ice in the Range 188 to 210 K at small Average Concentrations

2018 ◽  
Author(s):  
Christophe Delval ◽  
Michel J. Rossi
Keyword(s):  
Life Time ◽  
Data Sets ◽  
Atmospheric Conditions ◽  
Two Phase ◽  
Complex Behaviour ◽  
Water Ice ◽  
Ice Cloud ◽  
Film Evaporation ◽  
Ice Films ◽  
Evaporation Flux

Abstract. The evaporation flux Jev(H2O) of H2O from HCl-doped typically 1.5 μm or so thick vapor-deposited ice films has been measured in a combined quartz crystal microbalance (QCMB) – residual gas mass spectrometry (MS) experiment. Jev(H2O) has been found to show complex behaviour and to be a function of the average mole fraction χ(HCl) of HCl in the ice film ranging from 6 × 1014 to 3 × 1017 molecule cm−2 s−1 at 174–210 K for initial values χ0(HCl) ranging from 5 × 10−5 to 3 × 10−3 at the start of the evaporation. The dose of HCl on ice was in the range of 1 to 40 formal monolayers and the H2O vapor pressure was independent of χ(HCl) within the measured range and equal to that of pure ice down to 80 nm thickness. The temporal dependence of Jev(H2O) was correlated with (a) the evaporation range rb/e as the ratio of Jev(H2O) just before HCl-doping of the pure ice film and Jev(H2O) after observable HCl desorption towards the end of film evaporation, and (b) the remaining thickness dD below which Jev(H2O) decreases to less than 85 % of pure ice. The time dependence of Jev(H2O) from HCl-doped ice films suggests two limiting data sets, one associated with the occurrence of a two-phase pure ice/crystalline HCl hydrate binary phase (set A), and the other with a single phase amorphous HCl/H2O binary mixture (set B). The measured values of Jev(H2O) may lead to significant evaporative life-time extensions of HCl - contaminated ice cloud particles under atmospheric conditions, regardless of whether the structure corresponds to an amorphous or crystalline state of the HCl/H2O aggregate.

scholarly journals The influence of HCl on the evaporation rates of H<sub>2</sub>O over water ice in the range 188 to 210 K at small average concentrations

2018 ◽  
Vol 18 (21) ◽  
pp. 15903-15919
Author(s):  
Christophe Delval ◽  
Michel J. Rossi
Keyword(s):  
Quartz Crystal ◽  
Single Phase ◽  
Data Sets ◽  
Atmospheric Conditions ◽  
Two Phase ◽  
Water Ice ◽  
Ice Cloud ◽  
Film Evaporation ◽  
Ice Films ◽  
Evaporation Flux

Abstract. The evaporation flux Jev(H2O) of H2O from HCl-doped typically 1.5 µm or so thick vapor-deposited ice films has been measured in a combined quartz crystal microbalance (QCMB)–residual gas mass spectrometry (MS) experiment. Jev(H2O) has been found to show complex behavior and to be a function of the average mole fraction χHCl of HCl in the ice film ranging from 6×1014 to 3×1017 molecule cm−2 s−1 at 174–210 K for initial values χHCl0 ranging from 5×10-5 to 3×10-3 at the start of the evaporation. The dose of HCl on ice was in the range of 1 to 40 formal monolayers and the H2O vapor pressure was independent of χHCl within the measured range and equal to that of pure ice down to 80 nm thickness. The dependence of Jev(H2O) with increasing average χHCl was correlated with (a) the evaporation range rb∕e parameter, that is, the ratio of Jev(H2O) just before HCl doping of the pure ice film and Jev(H2O) after observable HCl desorption towards the end of film evaporation, and (b) the remaining thickness dD below which Jev(H2O) decreases to less than 85 % of pure ice. The dependence of Jev(H2O) with increasing average χHCl from HCl-doped ice films suggests two limiting data sets, one associated with the occurrence of a two-phase pure ice/crystalline HCl hydrate binary phase (set A) and the other with a single-phase amorphous HCl∕H2O binary mixture (set B). The measured values of Jev(H2O) may lead to significant evaporative lifetime extensions of HCl-contaminated ice cloud particles under atmospheric conditions, regardless of whether the structure corresponds to an amorphous or crystalline state of the HCl∕H2O aggregate.

ION IRRADIATION OF H2-LADEN POROUS WATER-ICE FILMS: IMPLICATIONS FOR INTERSTELLAR ICES

2015 ◽  
Vol 811 (2) ◽  
pp. 120 ◽  
Author(s):  
U. Raut ◽  
E. H. Mitchell ◽  
R. A. Baragiola
Keyword(s):  
Ion Irradiation ◽  
Water Ice ◽  
Ice Films ◽  
Interstellar Ices

Emission of ionic water clusters from water ice films bombarded by energetic projectiles

2004 ◽  
Vol 231-232 ◽  
pp. 72-77 ◽  
Author(s):  
Igor A. Wojciechowski ◽  
Uchkun Kutliev ◽  
Shixin Sun ◽  
Christopher Szakal ◽  
Nicholas Winograd ◽  
...  
Keyword(s):  
Water Clusters ◽  
Water Ice ◽  
Ice Films

A Comparison of Aphelion Cloud Belt Phase Functions Before and After the Mars Year 34 Global Dust Storm

2021 ◽  
Author(s):  
Alex Innanen ◽  
Brittney Cooper ◽  
Charissa Campbell ◽  
Scott Guzewich ◽  
Jacob Kloos ◽  
...  
Keyword(s):  
Dust Storm ◽  
Phase Function ◽  
Dust Storms ◽  
Ice Crystal ◽  
Ice Clouds ◽  
Water Ice ◽  
Ice Cloud ◽  
Sky Survey ◽  
Scattering Phase ◽  
Scattering Phase Function

&lt;p&gt;1. INTRODUCTION&lt;/p&gt;&lt;p&gt;The Mars Science Laboratory (MSL) is located in Gale Crater (4.5&amp;#176;S, 137.4&amp;#176;E), and has been performing cloud observations for the entirety of its mission, since its landing in 2012 [eg. 1,2,3]. One such observation is the Phase Function Sky Survey (PFSS), developed by Cooper et al [3] and instituted in Mars Year (MY) 34 to determine the scattering phase function of Martian water-ice clouds. The clouds of interest form during the Aphelion Cloud Belt (ACB) season (L&lt;sub&gt;s&lt;/sub&gt;=50&amp;#176;-150&amp;#176;), a period of time during which there is an increase in the formation of water-ice clouds around the Martian equator [4]. The PFSS observation was also performed during the MY 35 ACB season and the current MY 36 ACB season.&lt;/p&gt;&lt;p&gt;Following the MY 34 ACB season, Mars experienced a global dust storm which lasted from L&lt;sub&gt;s&lt;/sub&gt;~188&amp;#176; to L&lt;sub&gt;s&lt;/sub&gt;~250&amp;#176; of that Mars year [5]. Global dust storms are planet-encircling storms which occur every few Mars years and can significantly impact the atmosphere leading to increased dust aerosol sizes [6], an increase in middle atmosphere water vapour [7], and the formation of unseasonal water-ice clouds [8]. While the decrease in visibility during the global dust storm itself made cloud observation difficult, comparing the scattering phase function prior to and following the global dust storm can help to understand the long-term impacts of global dust storms on water-ice clouds.&lt;/p&gt;&lt;p&gt;2. METHODS&lt;/p&gt;&lt;p&gt;The PFSS consists of 9 cloud movies of three frames each, taken using MSL&amp;#8217;s navigation cameras, at a variety of pointings in order to observe a large range of scattering angles. The goal of the PFSS is to characterise the scattering properties of water-ice clouds and to determine ice crystal geometry.&amp;#160; In each movie, clouds are identified using mean frame subtraction, and the phase function is computed using the formula derived by Cooper et al [3]. An average phase function can then be computed for the entirety of the ACB season.&lt;/p&gt;&lt;p&gt;&lt;img src=&quot;https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.eda718c85da062913791261/sdaolpUECMynit/1202CSPE&amp;app=m&amp;a=0&amp;c=67584351a5c2fde95856e0760f04bbf3&amp;ct=x&amp;pn=gnp.elif&amp;d=1&quot; alt=&quot;Figure 1 &amp;#8211; Temporal Distribution of Phase Function Sky Survey Observations for Mars Years 34 and 35&quot; width=&quot;800&quot; height=&quot;681&quot;&gt;&lt;/p&gt;&lt;p&gt;Figure 1 shows the temporal distributions of PFSS observations taken during MYs 34 and 35. We aim to capture both morning and afternoon observations in order to study any diurnal variability in water-ice clouds.&lt;/p&gt;&lt;p&gt;3. RESULTS AND DISCUSSION&lt;/p&gt;&lt;p&gt;There were a total of 26 PFSS observations taken in MY 35 between L&lt;sub&gt;s&lt;/sub&gt;~50&amp;#176;-160&amp;#176;, evenly distributed between AM and PM observations. Typically, times further from local noon (i.e. earlier in the morning or later in the afternoon) show stronger cloud features, and run less risk of being obscured by the presence of the sun. In all movies in which clouds are detected, a phase function can be calculated, and an average phase function determined for the whole ACB season. &amp;#160;&lt;/p&gt;&lt;p&gt;Future work will look at the water-ice cloud scattering properties for the MY 36 ACB season, allowing us to get more information about the interannual variability of the ACB and to further constrain the ice crystal habit. The PFSS observations will not only assist in our understanding of the long-term atmospheric impacts of global dust storms but also add to a more complete image of time-varying water-ice cloud properties.&lt;/p&gt;

The Three-Cornered Hat Method for Estimating Error Variances of Three or More Atmospheric Data Sets – Part II: Evaluating Radio Occultation and Radiosonde Observations, Global Model Forecasts, and Reanalyses

2021 ◽  
Author(s):  
Therese Rieckh ◽  
Jeremiah P. Sjoberg ◽  
Richard A. Anthes
Keyword(s):  
Radio Occultation ◽  
State Of The Art ◽  
Specific Humidity ◽  
Data Sets ◽  
Error Growth ◽  
Atmospheric Conditions ◽  
Error Statistics ◽  
Weather And Climate ◽  
Atmospheric Data ◽  
The Impact

AbstractWe apply the three-cornered hat (3CH) method to estimate refractivity, bending angle, and specific humidity error variances for a number of data sets widely used in research and/or operations: radiosondes, radio occultation (COSMIC, COSMIC-2), NCEP global forecasts, and nine reanalyses. We use a large number and combinations of data sets to obtain insights into the impact of the error correlations among different data sets that affect 3CH estimates. Error correlations may be caused by actual correlations of errors, representativeness differences, or imperfect co-location of the data sets. We show that the 3CH method discriminates among the data sets and how error statistics of observations compare to state-of-the-art reanalyses and forecasts, as well as reanalyses that do not assimilate satellite data. We explore results for October and November 2006 and 2019 over different latitudinal regions and show error growth of the NCEP forecasts with time. Because of the importance of tropospheric water vapor to weather and climate, we compare error estimates of refractivity for dry and moist atmospheric conditions.

scholarly journals Day-time identification of summer hailstorm cells from MSG data

2013 ◽  
Vol 1 (5) ◽  
pp. 5453-5498 ◽  
Author(s):  
A. Merino ◽  
L. López ◽  
J. L. Sánchez ◽  
E. García-Ortega ◽  
E. Cattani ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Deep Convection ◽  
Detection Algorithm ◽  
Probability Of Detection ◽  
Phase Method ◽  
Data Sets ◽  
Liquid Water Path ◽  
Two Phase ◽  
Logistic Regression Models ◽  
Ebro Valley

Abstract. Identifying deep convection is of paramount importance, as it may be associated with extreme weather that has significant impact on the environment, property and the population. A new method, the Hail Detection Tool (HDT), is described for identifying hail-bearing storms using multi-spectral Meteosat Second Generation (MSG) data. HDT was conceived as a two-phase method, in which the first step is the Convective Mask (CM) algorithm devised for detection of deep convection, and the second a Hail Detection algorithm (HD) for the identification of hail-bearing clouds among cumulonimbus systems detected by CM. Both CM and HD are based on logistic regression models trained with multi-spectral MSG data-sets comprised of summer convective events in the middle Ebro Valley between 2006–2010, and detected by the RGB visualization technique (CM) or C-band weather radar system of the University of León. By means of the logistic regression approach, the probability of identifying a cumulonimbus event with CM or a hail event with HD are computed by exploiting a proper selection of MSG wavelengths or their combination. A number of cloud physical properties (liquid water path, optical thickness and effective cloud drop radius) were used to physically interpret results of statistical models from a meteorological perspective, using a method based on these "ingredients." Finally, the HDT was applied to a new validation sample consisting of events during summer 2011. The overall Probability of Detection (POD) was 76.9% and False Alarm Ratio 16.7%.

scholarly journals Experimental Investigation of Droplet Injections in the Vicinity of the Critical Point: A comparison of different model approaches

2017 ◽  
Author(s):  
Christoph Steinhausen ◽  
Grazia Lamanna ◽  
Bernhard Weigand ◽  
Rolf Stierle ◽  
Joachim Groß ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Raman Scattering ◽  
High Pressures ◽  
Region Of Interest ◽  
Theoretical Models ◽  
Nitrogen Atmosphere ◽  
Material Surface ◽  
Atmospheric Conditions ◽  
Mixing Processes ◽  
Two Phase

The disintegration process of liquid fuel within combustion chambers is one of the most important parameters forefficient and stable combustion. Especially for high pressures exceeding the critical value of the injected fluids the mixing processes are not fully understood yet. Recently, different theoretical macroscopic models have been introduced to understand breakdown of the classical two phase regime and predict the transition from evaporation to a diffuse-mixing process. In order to gain deeper insight into the physical processes of this transition, a parametric study of free-falling n-pentane droplets in an inert nitrogen atmosphere is presented. Atmospheric conditions varied systematically from sub- to supercritical values with respect to the fluid properties. An overlay of a diffuse lighted image with a shadowgram directly in the optical setup (front lighted shadowgraphy) was applied to simultaneously detect the presence of a material surface of the droplet as well as changes in density gradients in the surrounding atmosphere. The experimental investigation illustrates, that the presence of a material surface cannot be shown by a direct shadowgram. However, reflections and refractions caused by diffuse ambient illumination are able to indicate the presence of a material surface. In case of the supercritical droplet injections in this study, front lighted shadowgraphy clearly revealed the presence of a material surface, even when the pre-heated droplets are released into a supercritical atmosphere. This detection of the droplet interface indicates, that the droplet remains subcritical in the region of interest, even though it is injected into a supercritical atmosphere. Based on the adiabatic mixing assumption recent Raman-scattering results in the wake of the droplet are re-evaluated to compute the temperature distribution. Presented experimental findings as well as the re-evaluation of recent Raman scattering results are compared to thermodynamic models to predict the onset of diffuse-mixing and supercritical disintegration of the droplet. Additionally, a one dimensional evaporation model is used to evaluate the validity of the adiabatic mixing assumption in the estimation of the droplet temperature. The presented findings contribute to the understanding of recent theoretical models for prediction of spray and droplet disintegration and the onset of diffuse-mixing processes.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4635

Dimensionality Reduction with Unsupervised Feature Selection and Applying Non-Euclidean Norms for Classification Accuracy

2011 ◽  
pp. 91-109
Author(s):  
Amit Saxena ◽  
John Wang
Keyword(s):  
Classification Accuracy ◽  
Nearest Neighbor ◽  
Fitness Function ◽  
Synthetic Data ◽  
Feature Subset Selection ◽  
Second Phase ◽  
Data Sets ◽  
Feature Subset ◽  
K Nearest Neighbor ◽  
Two Phase

This paper presents a two-phase scheme to select reduced number of features from a dataset using Genetic Algorithm (GA) and testing the classification accuracy (CA) of the dataset with the reduced feature set. In the first phase of the proposed work, an unsupervised approach to select a subset of features is applied. GA is used to select stochastically reduced number of features with Sammon Error as the fitness function. Different subsets of features are obtained. In the second phase, each of the reduced features set is applied to test the CA of the dataset. The CA of a data set is validated using supervised k-nearest neighbor (k-nn) algorithm. The novelty of the proposed scheme is that each reduced feature set obtained in the first phase is investigated for CA using the k-nn classification with different Minkowski metric i.e. non-Euclidean norms instead of conventional Euclidean norm (L2). Final results are presented in the paper with extensive simulations on seven real and one synthetic, data sets. It is revealed from the proposed investigation that taking different norms produces better CA and hence a scope for better feature subset selection.

scholarly journals Transient Simulation of Underground Pumped Storage Hydropower Plants Operating in Pumping Mode

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1781 ◽  
Author(s):  
Javier Menéndez ◽  
Jesús M. Fernández-Oro ◽  
Mónica Galdo ◽  
Jorge Loredo
Keyword(s):  
Transient Process ◽  
Ideal Gas ◽  
Compressible Liquid ◽  
Transient Simulation ◽  
Atmospheric Conditions ◽  
Surge Tank ◽  
Two Phase ◽  
Vof Model ◽  
Pumping Mode ◽  
Pumped Storage

The increasing penetration of variable renewable energies (VRE) in the European electricity mix requires flexible energy storage systems (ESS), such as pumped storage hydropower (PSH). Disused mining voids from deep closed mines may be used as subsurface reservoirs of underground pumped-storage hydropower (UPSH) plants. Unlike conventional PSH plants, the air pressure in UPSH plants is variable and it differs from the atmospheric conditions. In this paper, the hydraulic transient process of an UPSH plant operating in pumping mode was investigated and a preliminary thermodynamic analysis of the closed surge tank was carried out. Analytical and CFD three-dimensional numerical simulations based on the volume of fluid (VOF) model with two-phase flow have been performed for analyzing the transient process. In the transient simulation, air and water are considered as ideal gas and compressible liquid, respectively. Different guide vanes closing schemes have been simulated. The obtained results show that the dimensioning of underground reservoir, surge tank, and air ducts is essential for ensuring the hydraulic performance and optimizing the operation of UPSH plants. The static pressure in the air duct, surge tank and lower reservoir reaches −1.6, 112.8 and −4 kPa, respectively, while a heat flux of −80 W was obtained through the surge tank walls.

scholarly journals Biodegradation of phenol and catechol in cloud water: comparison to chemical oxidation in the atmospheric multiphase system

2020 ◽  
Vol 20 (8) ◽  
pp. 4987-4997 ◽  
Author(s):  
Saly Jaber ◽  
Audrey Lallement ◽  
Martine Sancelme ◽  
Martin Leremboure ◽  
Gilles Mailhot ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Chemical Oxidation ◽  
Cloud Water ◽  
Multiphase System ◽  
Data Sets ◽  
Biological Processes ◽  
Atmospheric Conditions ◽  
Oxidation Reactions ◽  
Atmospheric Models ◽  
Degradation Rates

Abstract. The sinks of hydrocarbons in the atmosphere are usually described by oxidation reactions in the gas and aqueous (cloud) phases. Previous lab studies suggest that in addition to chemical processes, biodegradation by bacteria might also contribute to the loss of organics in clouds; however, due to the lack of comprehensive data sets on such biodegradation processes, they are not commonly included in atmospheric models. In the current study, we measured the biodegradation rates of phenol and catechol, which are known pollutants, by one of the most active strains selected during our previous screening in clouds (Rhodococcus enclensis). For catechol, biodegradation is about 10 times faster than for phenol. The experimentally derived biodegradation rates are included in a multiphase box model to compare the chemical loss rates of phenol and catechol in both the gas and aqueous phases to their biodegradation rate in the aqueous phase under atmospheric conditions. Model results show that the degradation rates in the aqueous phase by chemical and biological processes for both compounds are similar to each other. During day time, biodegradation of catechol is even predicted to exceed the chemical activity in the aqueous phase and to represent a significant sink (17 %) of total catechol in the atmospheric multiphase system. In general, our results suggest that atmospheric multiphase models may be incomplete for highly soluble organics as biodegradation may represent an unrecognized efficient loss of such organics in cloud water.

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