Atmospheric Condensation Research Articles

Resolving Convection of CO2 Ice Clouds in the Martian Polar Nights

AbstractMartian CO2 ice clouds are intriguing features, representing a rare occurrence of atmospheric condensation of a major component. These clouds play a crucial role due to their radiative properties, interactions with surface, and coupling with microphysical cycles of aerosols. Observations have been limited, prompting modeling studies to understand their formation and dynamics. Here, we present the first high‐resolution 3D simulations of CO2 ice clouds using a Large‐Eddy Simulation (LES) model incorporating CO2 microphysics. We investigate cloud formation in idealized temperature perturbations in the polar night. A reference simulation with a −2K perturbation demonstrates that the formed CO2 ice cloud possesses a convective potential, leading to its ascent in the troposphere. We determine the timescales and orders of magnitude of various phenomena involved in the lifecycle of a CO2 ice cloud. Sensitivity tests show that convection can be inhibited or intensified by the thermodynamic and microphysical conditions of the simulated environment.

New characteristics of Meiyu precipitation changes in the middle and lower reaches of the Yangtze River since 2000

This study comprehensively analyzed the long-term changes of Meiyu in the middle and lower reaches of the Yangtze River with regard to precipitation, precipitation threshold, and interdecadal changes in atmospheric circulation. Results revealed obvious new features of Meiyu precipitation since 2000. (1) Meiyu precipitation shows a significant linear increase trend, with an average increment of 73.5 mm every 10 years. The increase in torrential rain is the most significant, accounting for 61% of the total precipitation increase, and its proportion has been increasing, while the proportions of light, moderate, and heavy rain in the total precipitation have been decreasing. (2) At the interdecadal scale, Meiyu precipitation and the local surface average temperature show opposite changes. Meiyu precipitation decreases by approximately 150 mm for every 1°C increase in the average temperature. This inverse correlation was not evident before 2000. (3) The saturated specific humidity in this area shows a significant increasing trend, indicating that precipitation in this area is caused by a higher threshold of atmospheric saturation and condensation, which may be a reason for the low Meiyu precipitation during high-temperature years. (4) The main atmospheric circulation in East Asia associated with Meiyu shows clear interdecadal changes, including the Western North Pacific Subtropical High and South Asian High having become significantly stronger and having extended westward and eastward, respectively, thereby facilitating the occurrence and persistence of Meiyu precipitation. The atmospheric circulation patterns associated with Meiyu, such as the Western North Pacific Subtropical High and South Asian High, have more significant impacts on Meiyu precipitation.

Statistical analysis and environmental impact of pre-existing particle growth events in a Northern Chinese coastal megacity: A 725-day study in 2010–2018

Pre-existing particles usually constitute the major fraction of atmospheric particles, except during some episodes in the presence of strong emissions and/or secondary generation of fresh particles. Previous case studies have investigated the growth of pre-existing particles and their potential environmental and climate impacts. However, there is limited knowledge about the statistical characteristics of these growth events and related effects. In this study, we examine pre-existing particle growth events using a large dataset (725 days from 2010 to 2018) collected at a coastal megacity in northern China. The occurrence frequency of pre-existing particle growth events was 12.4 % (90 out of 725 days). When these events were related to measured criteria air pollutants, no significant differences were found in PM2.5, SO2, NO2 and NO2 + O3 concentrations between periods with and without pre-existing particle growth events. These 90-day events can be further classified into two categories, i.e., Category 1, with 68 % of events representing the growth of pre-existing particles alone, and Category 2, with 32 % of events representing the simultaneous growth of pre-existing and newly formed particles. In Category 2, the growth rates of pre-existing particles and newly formed particles were close in 21 % of the cases, while pre-existing particles exhibited significantly larger growth rates in 69 % of the cases. Conversely, in 10 % of the cases, the growth rates of newly formed particles were larger. The different growth rate mechanisms were discussed in terms of the volatility of atmospheric condensation vapors. In addition, we present case studies on the impact of pre-existing particle growth on cloud condensation nuclei simultaneously measured, specifically considering the chemistry of condensation vapors and pre-existing particles.

Modifications on the coastal atmospheric sulfur and cloud condensation nuclei along the Eastern China seas by shipping fuel transition

Marine fuel combustion from shipping releases SO2 and forms sulfate particles, which may alter low cloud characteristics. A series of strategies were implemented to control the sulfur content of ship fuel oil from 2018 to 2020, offering insights into the effects of the ship fuel oil transition on sulfur-related pollutants and the consequent cloud condensation nuclei (CCN) in the atmosphere. Compared to 2018 in the southeast China waters, shipping SO2 emission decreased by 78 % in 2020, resulting in a 76 % reduction in ship-related total sulfur concentration, and a decrease of 54 % in CCN number concentration under supersaturation 0.2 % (CCN0.2) contributed by shipping. The response of CCN0.2 to ship-related sulfate modification is more pronounced in relatively clean environments than polluted environments, highlighting the uneven changes in coastal CCN along the Eastern China Sea induced by the ship fuel policies. CCN can trigger the formation of cloud droplets, 2020 fuel regulation may have and will reduce the cooling radiative forcing effect with strong spatial heterogeneity. The study provides insights into the variations in coastal atmospheric sulfur-related pollutants and CCN in uneven response to changes in ship fuel oil, prompting the need for further comprehensive assessments of the climate effects resulting from potential shifts in ship fuel use in the future.

URANIUM BEHAVIOR DURING THE FORMATION AND SUBSEQUENT STORAGE OF SOLID RADIOACTIVE WASTES FROM CONVERSION PRODUCTION

A complex of physicochemical studies of solid radioactive wastes (RW) of the near-surface storage facility from conversion uranium production was carried out. It has been established that the composition of the wastes is represented mainly by calcium compounds: gypsum, calcite, and calcium fluoride. Uranium is distributed throughout the entire volume of wastes. At the same time, uranium is unevenly concentrated along the depth of the sludge. The content of uranium in the wastes is 0.005-0.65 wt. %. Uranium was predominantly adsorbed on the surface of sludge by main components during the formation of the wastes solid phase. Uranium was partially precipitated in the form of calcium-containing weeksite Ca2(UO2)2(Si2O5)3·10H2O, uranophane-alpha Ca(UO2)2(SiO3OH)2·5H2O, and urankalcarite Ca(UO2)3CO3(OH)6·3H2O. The isotopic composition of uranium contained in the storage wastes corresponds, within the error, to the normal isotopic composition of natural uranium. Near-surface storage is constantly exposed to natural factors. Infiltration of atmospheric condensation leads to leaching of some components from solid RW. At the same time, uranium goes into solution in the form of [(UO2)2CO3(OH)3]-, [UO2(CO3)2]2-, [UO2(CO3)3]4- and Ca2UO2(CO3)3. The subsequent migration of uranium with infiltrating water contributes to its distribution within the entire sludge field, including the reclamation soil layer and the near-surface pond. In some areas of the storage facility, the uranium content in the reclamation soil layer reaches 0.043 wt.%. The concentration of uranium in the pond was 17.97 mg L-1. The chemical composition of the pond water was characterized by a high content of chloride-ions (1.29 g L-1), calcium (630 mg L-1), sulfate-ions (224 mg L-1), hydrocarbonates (122 mg L-1). The pond is connected to groundwater, which increases the risk of pollutants escaping beyond the storage facility. For citation: Skripchenko S.Yu., Titova S.М., Nalivaiko K.A., Semenishchev V.S. Uranium behavior during the formation and subsequent storage of solid radioactive wastes from conversion production. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 77-86. DOI: 10.6060/ivkkt.20246705.6925.

Creation of New Types of Power Supply and Life Support Systems for Spacecraft Powered by a Solar Panel

The work of power supply and life support systems of spacecraft is completely based on consumables, delivered from Earth, the mass, and dimensions of which increase in direct proportion to the duration of the space expedition and the number of crew members. Therefore, today a power supply system is used on board a spacecraft that provides onboard electrical energy for the operation of all on-board equipment (engine, control, communications, and heating systems) by generating direct electric current using a generator, converting chemical energy into electrical energy, using fuel cells, powered by supercritical liquid hydrogen and liquid oxygen, delivered from Earth. The life support system, used today on the spacecraft, includes: system for regenerating water from atmospheric humidity condensate in a spacecraft cabin, a water regeneration system from urine, system of generating oxygen and hydrogen during the electrolysis of water in microgravity conditions, a system for utilizing carbon dioxide, removing harmful micro impurities, operating at the expense of internal resources spacecraft during space flight. Thus, the task arises of developing new types of power supply and life support systems, including the development of new and improvement of existing technologies for continuous charging of spacecraft fuel cells with hydrogen and oxygen, generating onboard electricity without the use of “Earth tanks” with supercritical liquid hydrogen and liquid oxygen, improvement of existing oxygen and hydrogen generation systems, regeneration of water from condensate of atmospheric moisture and waste products of astronauts, removal of harmful micro impurities and cultivation of rapidly multiplying microalgae on the spacecraft during a long space flight. The article presents a new type of power supply and life support systems for spacecraft, powered by a solar panel, which includes the developed new technologies: an oxygen and hydrogen gas generator, which makes it possible to economically and easily separately produce oxygen, hydrogen and drinking water to enrich the atmosphere with oxygen and replenish the drinking supplies of the spacecraft cabin, continuously charge the fuel cells of the spacecraft with hydrogen and oxygen, produced for the uninterrupted generation of onboard electricity; a separator for purification of technical wastewaters from harmful solid inclusions and pathogenic microbes and obtaining drinking water from them, regeneration of drinking water from urine, excreted by astronauts, in quantities sufficient for consumption of this water by astronauts during a long space flight; a concentrator that receives a solution with microalgae cells from a space photo bioreactor, growing microalgae under weightless conditions, which utilizes carbon dioxide released during the breathing of astronauts, produces oxygen to enrich the atmosphere of the spacecraft cabin with oxygen through photosynthesis. A concentrator permits to obtain a high-quality concentrate of cells of rapidly multiplying microalgae and supplement the crew's diet by the biggest part of this concentrate, and to replenish the space photo bioreactor with the remainder of the concentrate and nutrient solution in order to obtain enough biomass for a long space flight.

Artificial gravity in heat and mass exchange apparatus for the life support system of manned space missions

Different water recovery systems for deep space flight are analyzed; the existing systems and their shortcomings are briefly shown. The construction of a centrifugal mass transfer apparatus is presented, it could work in weightlessness conditions. The experimental data for the centrifugal apparatus in the mode of separation of the gas and liquid mixture are presented. The pressure was about 8 meters of water column for proposed construction. The formula for calculating the pressure for a scoop pump is given, which takes into account the rotation frequency, volume flow rate, the geometric dimensions and location of the scoop. Principle schemes for using a new centrifugal mass exchange device for water recovery systems and for capturing atmospheric moisture condensate are proposed. The features of the proposed schemes are analyzed and their potential advantages are determined. The main tasks for future experimental studies of the heat and mass transfer centrifugal apparatus are defined.

Toward sustainable landscape irrigation using a novel design for water collection systems that use atmospheric moisture condensation

Abstract This paper introduces a novel design that uses high-emissivity materials with no hydrophobic surfaces to increase the speed of condensation and the dropping-off process in water collection systems from atmospheric moisture. The design incorporates simple and low-cost technology that takes advantage of advanced material properties to enable sustainable irrigation in regions characterized by water resource scarcity, generally favoring greening. The concept is based on the application of universal physics principles such as dew point, wetting and antiwetting, and material emissivity coefficients. The innovative collection system design and experimentation confirm the feasibility of collecting water from the air in various semi-arid regions with a low number of rainy days. The first novel aspect of the collection system design is the rapid increase in condensation and the use of materials with a high capacity to release collected water to address unwanted evaporation. The second novel feature is that the volume is reduced, and the system is flexible and inexpensive, allowing it to be distributed across a specific landscape. Reduced construction costs and ease of use demonstrate the real possibility of its use in developing and poor countries to first increase vegetation diffusion and then contribute to sustainable agriculture and green architecture.

The extremely high albedo of LTT 9779 b revealed by CHEOPS

Context. Optical secondary eclipse measurements of small planets can provide a wealth of information about the reflective properties of these worlds, but the measurements are particularly challenging to attain because of their relatively shallow depth. If such signals can be detected and modeled, however, they can provide planetary albedos, thermal characteristics, and information on absorbers in the upper atmosphere. Aims. We aim to detect and characterize the optical secondary eclipse of the planet LTT 9779 b using the CHaracterising ExOPlanet Satellite (CHEOPS) to measure the planetary albedo and search for the signature of atmospheric condensates. Methods. We observed ten secondary eclipses of the planet with CHEOPS. We carefully analyzed and detrended the light curves using three independent methods to perform the final astrophysical detrending and eclipse model fitting of the individual and combined light curves. Results. Each of our analysis methods yielded statistically similar results, providing a robust detection of the eclipse of LTT 9779 b with a depth of 115±24 ppm. This surprisingly large depth provides a geometric albedo for the planet of 0.80−0.17+0.10, consistent with estimates of radiative-convective models. This value is similar to that of Venus in our own Solar System. When combining the eclipse from CHEOPS with the measurements from TESS and Spitzer, our global climate models indicate that LTT 9779 b likely has a super metal-rich atmosphere, with a lower limit of 400× solar being found, and the presence of silicate clouds. The observations also reveal hints of optical eclipse depth variability, but these have yet to be confirmed. Conclusions. The results found here in the optical when combined with those in the near-infrared provide the first steps toward understanding the atmospheric structure and physical processes of ultrahot Neptune worlds that inhabit the Neptune desert.

Creation of New Types of Power Supply and Life Support Systems for Spacecraft Powered by a Solar Panel

The work of power supply and life support systems of spacecraft is completely based on consumables, delivered from Earth, the mass, and dimensions of which increase in direct proportion to the duration of the space expedition and the number of crew members. Therefore, today a power supply system is used on board a spacecraft that provides onboard electrical energy for the operation of all on-board equipment (engine, control, communications, and heating systems) by generating direct electric current using a generator, converting chemical energy into electrical energy, using fuel cells, powered by supercritical liquid hydrogen and liquid oxygen, delivered from Earth. The life support system, used today on the spacecraft, includes: system for regenerating water from atmospheric humidity condensate in a spacecraft cabin, a water regeneration system from urine, system of generating oxygen and hydrogen during the electrolysis of water in microgravity conditions, a system for utilizing carbon dioxide, removing harmful micro impurities, operating at the expense of internal resources spacecraft during space flight. Thus, the task arises of developing new types of power supply and life support systems, including the development of new and improvement of existing technologies for continuous charging of spacecraft fuel cells with hydrogen and oxygen, generating onboard electricity without the use of “Earth tanks” with supercritical liquid hydrogen and liquid oxygen, improvement of existing oxygen and hydrogen generation systems, regeneration of water from condensate of atmospheric moisture and waste products of astronauts, removal of harmful micro impurities and cultivation of rapidly multiplying microalgae on the spacecraft during a long space flight. The article presents a new type of power supply and life support systems for spacecraft, powered by a solar panel, which includes the developed new technologies: an oxygen and hydrogen gas generator, which makes it possible to economically and easily separately produce oxygen, hydrogen and drinking water to enrich the atmosphere with oxygen and replenish the drinking supplies of the spacecraft cabin, continuously charge the fuel cells of the spacecraft with hydrogen and oxygen, produced for the uninterrupted generation of onboard electricity; a separator for purification of technical wastewaters from harmful solid inclusions and pathogenic microbes and obtaining drinking water from them, regeneration of drinking water from urine, excreted by astronauts, in quantities sufficient for consumption of this water by astronauts during a long space flight; a concentrator that receives a solution with microalgae cells from a space photo bioreactor, growing microalgae under weightless conditions, which utilizes carbon dioxide released during the breathing of astronauts, produces oxygen to enrich the atmosphere of the spacecraft cabin with oxygen through photosynthesis. A concentrator permits to obtain a high-quality concentrate of cells of rapidly multiplying microalgae and supplement the crew's diet by the biggest part of this concentrate, and to replenish the space photo bioreactor with the remainder of the concentrate and nutrient solution in order to obtain enough biomass for a long space flight.

Preferred Mode of Atmospheric Water Vapor Condensation on Nanoengineered Surfaces: Dropwise or Filmwise?

Condensing atmospheric water vapor on surfaces is a sustainable approach to addressing the potable water crisis. However, despite extensive research, a key question remains: what is the optimal combination of the mode and mechanism of condensation as well as the surface wettability for the best possible water harvesting efficacy? Here, we show how various modes of condensation fare differently in a humid air environment. During condensation from humid air, it is important to note that the thermal resistance across the condensate is nondominant, and the energy transfer is controlled by vapor diffusion across the boundary layer and condensate drainage from the condenser surface. This implies that, unlike condensation from pure steam, filmwise condensation from humid air would exhibit the highest water collection efficiency on superhydrophilic surfaces. To demonstrate this, we measured the condensation rates on different sets of superhydrophilic and superhydrophobic surfaces that were cooled below the dew points using a Peltier cooler. Experiments were performed over a wide range of degrees of subcooling (10-26 °C) and humidity-ratio differences (5-45 g/kg of dry air). Depending upon the thermodynamic parameters, the condensation rate is found to be 57-333% higher on the superhydrophilic surfaces compared to the superhydrophobic ones. The findings of the study dispel ambiguity about the preferred mode of vapor condensation from humid air on wettability-engineered surfaces and lead to the design of efficient atmospheric water harvesting systems.

Defect-Density-Controlled Phase-Change Phenomena.

Juxtaposing hydrophilicity and hydrophobicity on the same surface, known as hybrid surface engineering, can enhance phase-change heat transfer. However, controlling hydrophilicity on hybrid surfaces in a scalable fashion is a challenge, limiting their application. Here, using widely available metal meshes with variable dimensions and by controlling the patterning pressure, we scalably fabricate hybrid surfaces having spot and gridlike patterns using stamping. Using fog harvesting in a controlled chamber, we show that optimized hybrid surfaces have a ∼37% higher fog harvesting rate when compared to homogeneous superhydrophobic surfaces. Furthermore, condensation frosting experiments reveal that, on grid-patterned hybrid surfaces, frost propagates at ∼160% higher velocity and provides ∼20% less frost coverage when compared to homogeneous superhydrophobic surfaces. During defrost, our hybrid surfaces retain more water when compared to superhydrophobic surfaces due to the presence of hydrophilic patterns and melt water pinning. We adapt our fabrication technique to roll-to-roll patterning, demonstrating wettability contrast on round metallic geometries via atmospheric water vapor condensation. This work provides guidelines for the rapid, substrate-independent, and scalable fabrication of hybrid wettability surfaces for a wide variety of applications.

Characteristics and source of soil condensation water in Guanzhong Plain, China

We determined the quantity and source of soil water condensation versus atmospheric vapor condensation in Guanzhong Plain and explored their role in water balance, using three different types of hand-made micro-lysimeters (open-ends, top-seal, and bottom-seal designs). Field monitoring of the vapor condensation process was carried out from late September to late October in 2018 and from March to May in 2019 using the weighing method. Results showed that during the monitoring period, condensation occurred every day without rainfall event. The maximum daily condensation for the open-ends, top-seal and bottom-seal designs were 0.38, 0.27 and 0.16 mm, respectively, indicating that vapor flow in soil pores was the main source of soil water condensation, and that the measurement using the open-ended micro-lysimeter could faithfully reflect the amount of condensation in Guanzhong Plain. During the monitoring period, total soil water condensation reached 14.94 mm, accounting for 12.8% of the precipitation in the same period (116.4 mm), and the ratio of atmospheric vapor condensation to soil vapor condensation was 0.59:1.

Pushing the Limit of Beetle‐Inspired Condensation on Biphilic Quasi‐Liquid Surfaces

AbstractMassive studies concern the development of low‐carbon water and energy systems. Specifically, surfaces with special wettability to promote vapor‐to‐liquid condensation have been widely studied, but current solutions suffer from poor heat transfer performances due to inefficient droplet removal. In this study, the limit of condensation on a beetle‐inspired biphilic quasi‐liquid surface (QLS) in a steam environment is pushed, which provides a heat flux 100 times higher than that in atmospheric condensation. Unlike the beetle‐inspired surfaces that have sticky hydrophilic domains, the biphilic QLS consists of PEGylated and siloxane polymers as hydrophilic and hydrophobic quasi‐liquid patterns with the contact angle hysteresis of 3° and 1°, respectively. More importantly, each hydrophilic slippery pattern behaves like a slippery bridge that accelerates droplet coalescence and removal. As a result, the condensed droplets grow rapidly and shed off. It is demonstrated that the biphilic‐striped QLS shows a 60% higher water harvesting rate in atmospheric condensation and a 170% higher heat transfer coefficient in steam condensation than the conventional beetle‐inspired surface. This study provides a new paradigm to push the limit of condensation heat transfer at a high heat flux, which sheds light on the next‐generation surface design for water and energy sustainability.

Changes in the height of the pollution boundary layer and their meteorological effects on the distribution of surface ozone concentrations

Focusing on the key air pollution regions in China by using hourly automatic weather data, ground-based and high-altitude meteorological sounding data, and near-surface O3 monitoring data, here, we try to quantify the relationship between boundary layer meteorological condition and near-surface O3 concentrations. The key meteorological element includes changes in solar zenith angle, cloud height, atmospheric condensation rate, and the associated change in the boundary layer height. We also try to better understand the mechanisms by which meteorological conditions affect near-surface O3 concentrations, and it is found that the exponential increase in near-surface O3 concentrations after sunrise (called the O3 concentration entrainment, EZ) is meaningfully associated with exceeding the threshold of a water vapor condensation rate (fc) that is often closely linked to a significant rise in the pollution boundary layer and that this proves to be diagnostically important for understanding the O3 EZ. Diurnal variations in solar zenith angle and boundary layer height are key meteorological factors influencing the large increase in near-surface O3 concentration entrainment.

Global shockwaves of the Hunga Tonga-Hunga Ha’apai volcano eruption measured at ground stations

The eruption of the Tonga volcano created globally propagating spherical shockwaves in the atmosphere. Analyses are done to data from two southern U.S. stations of the author sampling at 3-21s intervals and 189 weather stations at 1-5min intervals. The shockwaves arrived from two routes in the atmosphere: the shortest spherical arc and the longer spherical arc through the antipole. In most stations, signals up to the 6th path of shockwaves were recorded as the waves traveled around the globe multiple times. The speed of shockwaves is estimated to be 309.5± 2.9m/s, consistent with the speed of sound at the top of the troposphere where a waveguide exists. Discussion is made on the post-shockwave ringing of 4-8min as higher amplitude oscillations above the level of pre-shockwaves background noise. A theoretical wave dispersion is derived which verifies that the spherical shockwave's phase speed is the same as the speed of sound.

Biological soil crusts enhance the role of non-rainfall water in the water input in alpine sandy land ecosystems

• High amounts of non-rainfall water (10%–15% of water input) occur in the alpine sandy land. • Biological soil crusts increase the daily mean non-rainfall water amount by 23%–30%. • Biological soil crusts enhance non-rainfall water accumulation and dissipation rates by >20%. • The effects of soil crusts can be attributed to changes in soil physicochemical properties. • The principal source of non-rainfall water is atmospheric vapor (∼60%). Non-rainfall water originating from atmospheric and soil vapors is a major water source that supports dryland ecosystem functioning. The alpine sandy land ecosystem is fragile, where biological soil crusts develop widely on the soil surface and play a critical role in regulating surface hydrological processes. Yet, the effects of biological soil crusts on non-rainfall water in the alpine sandy land remain unclear. Therefore, we investigated the patterns and main sources of non-rainfall water under different biological soil crusts in the Qinghai–Tibet Plateau region during the growing season (May–September 2017). Micro-lysimeters were used to measure the amount of non-rainfall water in surface soil (0–10 cm) covered with moss and algae crusts in an interdune area. The results revealed that non-rainfall water occurred for at least 12 h·d −1 (7 p.m.–7 a.m.) and disappeared for 5 h (7 a.m.–12 a.m.). The daily mean non-rainfall water amount ranged between 0.324 and 0.426 mm. Differences in the physical and chemical properties of surface soil caused by biological soil crusts affected the accumulation and dissipation of non-rainfall water. The accumulation and dissipation rates of non-rainfall water under biological soil crusts were respectively 1.22–1.32-fold ( F = 8.01, P < 0.05) and 1.21–1.27-fold ( F = 8.86, P < 0.05) higher than those of bare sand. Biological soil crusts also increased the amount of total non-rainfall water by 23.41%–30.39% ( F = 5.367, P < 0.05), accounting for 2.4%–3.0% of the total water input. Atmospheric vapor condensation was the principal source of non-rainfall water (>60%). Nevertheless, biological soil crusts increased both atmospheric and soil vapor condensation by 29.44%–39.98% ( F = 12.45, P < 0.05) and 13.09–13.94% ( F = 5.91, P < 0.05), respectively. Although non-rainfall water contributed only 10%–15% of the total water input, it constituted a main water input to the ecosystem during the dry period of less rainfall (up to 20%, 19.72 vs. 95.72 mm). In conclusion, non-rainfall water, especially atmospheric vapor condensation, makes a non-negligible contribution to water input in the alpine sandy land ecosystem, for which biological soil crusts enhance the role of non-rainfall water in the water input in surface soil water balance dynamics.

Role of gas–molecular cluster–aerosol dynamics in atmospheric new-particle formation

New-particle formation from vapors through molecular cluster formation is a central process affecting atmospheric aerosol and cloud condensation nuclei numbers, and a significant source of uncertainty in assessments of aerosol radiative forcing. While advances in experimental and computational methods provide improved assessments of particle formation rates from different species, the standard approach to implement these data in aerosol models rests on highly simplifying assumptions concerning gas–cluster–aerosol dynamics. To quantify the effects of the simplifications, we develop an open-source tool for explicitly simulating the dynamics of the complete particle size spectrum from vapor molecules and molecular clusters to larger aerosols for multi-compound new-particle formation. We demonstrate that the simplified treatment is a reasonable approximation for particle formation from weakly clustering chemical compounds, but results in overprediction of particle numbers and of the contribution of new-particle formation to cloud condensation nuclei for strongly clustering, low-concentration trace gases. The new explicit approach circumvents these issues, thus enabling robust model–measurement comparisons, improved assessment of the importance of different particle formation agents, and construction of optimal simplifications for large-scale models.

Determination of atmospheric column condensate using active and passive remote sensing technology

Abstract. To further exploit atmospheric cloud water resources (CWRs), it is necessary to correctly evaluate the number of CWRs in an area. The CWRs are hydrometeors that have not participated in precipitation formation at the surface and are suspended in the atmosphere to be exploited and maximise possible precipitation in the atmosphere (Zhou et al., 2020). Three items are included in CWRs: the existing hydrometeors at a certain time, the influx of atmospheric hydrometeors along the boundaries of the study area, and the mass of hydrometeors converted from water vapour through condensation or desublimation, defined as condensate. Condensate constitutes the most important part of CWRs. At present, there is a lack of effective observation methods for atmospheric column condensate evaluation, and direct observation data of CWRs are thus insufficient. A detection method for atmospheric column condensate is proposed and presented. The formation of condensate is closely related to atmospheric meteorological parameters (e.g. temperature and vertical airflow velocity). The amount of atmospheric column condensate can be calculated by the saturated water vapour density and the ascending velocity at the cloud base and top. Active and passive remote sensing technologies are applied to detect the mass of atmospheric column condensate. Combining millimetre cloud radar, lidar and microwave radiometers can suitably observe the vertical velocity and temperature at the cloud boundary. The saturated vapour density can be derived from the temperature, and then, water vapour flux and the maximum possible condensate can be deduced. A detailed detection scheme and data calculation method are presented, and the presented method can realise the determination of atmospheric column condensate. A case of cloud layer change before precipitation is considered, and atmospheric column condensate is deduced and obtained. This is the first application, to our knowledge, of observations for atmospheric column condensate evaluation, which is significant for research on the hydrologic cycle and the assessment of CWRs.

Atmospheric Sulfuric Acid Dimer Formation in a Polluted Environment.

New particle formation (NPF) contributes significantly to atmospheric particle number concentrations and cloud condensation nuclei (CCN). In sulfur-rich environments, field measurements have shown that sulfuric acid dimer formation is likely the critical step in NPF. We investigated the dimer formation process based upon the measured sulfuric acid monomer and dimer concentrations, along with previously reported amine concentrations in a sulfur-rich atmosphere (Atlanta, USA). The average sulfuric acid concentration was in the range of 1.7 × 107–1.4 × 108 cm−3 and the corresponding neutral dimer concentrations were 4.1 × 105–5.0 × 106 cm−3 and 2.6 × 105–2.7 × 106 cm−3 after sub-collision and collision ion-induced clustering (IIC) corrections, respectively. Two previously proposed acid–base mechanisms (namely AA and AB) were employed to respectively estimate the evaporation rates of the dimers and the acid–amine complexes. The results show evaporation rates of 0.1–1.3 s−1 for the dimers based on the simultaneously measured average concentrations of the total amines, much higher than those (1.2–13.1 s−1) for the acid–amine complexes. This indicates that the mechanism for dimer formation is likely AA through the formation of more volatile dimers in the initial step of the cluster formation.