Global oxygen distributions at the Earth's surface.

There are frequent and intensive periods of heavy rain in the arid areas of southern Xinjiang. This study uses a typical rainstorm process in the South Xinjiang Basin to investigate the weather, physical mechanisms, mesoscale characteristics, and income and expenditure characteristics of water vapor sources, analyzing them using the observation data from southern Xinjiang regional automatic stations, ERA5 reanalysis data, multi-source satellite data, and WRF numerical simulation results. The study results show that torrential rain processes occur in the double-body distribution of the South Asian High in the upper troposphere, which is “high in the east and low in the west,” with “two ridges and one trough” in the middle layer. The development and movement of the low vortex, the configuration of low-level convergence and high-level divergence, and vertical upward movement provide favorable dynamic conditions for heavy rain. Additionally, the Black Sea, the Caspian Sea, the Aral Sea, the Arabian Sea, and the Bay of Bengal are important water vapor sources for this rainstorm. The water vapor reaches the South Xinjiang Basin along westward, southwest, and eastward paths. It is mainly imported into the South Xinjiang Basin from 500 to 300 hPa on the southern border and 700–500 hPa on the west, north, and east borders, and exported from 500 to 300 hPa on the eastern border. The simulation results show that the change in water vapor content significantly influences the precipitation intensity and range. The water vapor transport at the southern boundary contributes the most precipitation during the rainstorm. As the water vapor in the rainstorm area increases (decreases), the ascending motion is strengthened (weakened), the low-level convergence and high-level divergence are strengthened (weakened), the water vapor transport to the middle and high levels increases (decreases), and the precipitation increases (decreases).

Chemical composition of melanosomes, lipofuscin and melanolipofuscin granules of human RPE tissues

Water vapor transport is an important foundation and prerequisite for the occurrence of rainstorms. Consequently, the understanding of water vapor transport as well as the sources of water vapor during rainstorm processes should be considered as essential to study the formation mechanism of rainstorms. In this study, the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model is adopted for backward tracking of water vapor transport trajectories and sources during the “7·20” extraordinary heavy rain process in Zhengzhou City of China that occurred on 20 July 2021. On this basis, the trajectory clustering method is applied to quantitatively analyze the contributions of water vapor sources, aiming to provide a basis for exploring the maintenance mechanism of this extreme rainstorm event. The spatio-temporal characteristics of this rainstorm event show that there are 4 consecutive days with the precipitation reaching or exceeding the rainstorm level across the whole Zhengzhou City, with the daily rainfall amounts at eight national meteorological stations all breaking their respective historical extreme values. The regional-averaged rainfall amount in Zhengzhou City is 527.4 mm, while the maximum accumulated rainfall amount reaches 985.2 mm at Xinmi station and the maximum hourly rainfall amount at Zhengzhou national meteorological station reaches 201.9 mm h−1. The water vapor sources for this rainfall process, ranked in descending order of contribution, are the Western Pacific, inland areas of Northwest China and South China, and South China Sea. The water vapor at lower levels is mainly transported from the Western Pacific and the South China Sea, while those from the inland areas of Northwest China and South China provide a supply of water vapor at upper levels to a certain extent. The water vapor at 950 hPa is mainly sourced from the Western Pacific and South China Sea, accounting for 56% and 44%, respectively. The water vapor at 850 hPa mainly derives from the Western Pacific and the inland areas of South China, contributing 58% and 34% of the total, respectively. The water vapor at 700 hPa mainly comes from the inland areas of Northwest China and South China Sea. Specifically, the water vapor from inland Northwest China contributes 44% of the total, acting as the primary source. The water vapor at 500 hPa is mainly transported from the inland areas of South China and Northwest China, with that from the inland South China (56%) being more prominent. The water vapor at all levels is mainly transported to the rainstorm region through the eastern and southern regions of China from the source areas. Additionally, there are some differences in the water vapor trajectories at a 6 h interval.

Quantitative chemical analysis of ocular melanosomes in stained and non-stained tissues

On 25 and 26 October 1986 the air in Cambridge, Massachusetts was monitored for O2 and CO2 mole fraction. O2 concentrations were detected from changes in the relative refractivity of dried air between two lines of 198Hg at 2537.269 and 4359.562 A using dual-wavelength interferometry. Changes in oxygen mole fraction were resolved with two-minute time resolution to a precision of ±2.0 ppm. Changes in O2 were shown to be strongly anticorrelated with changes in CO2 as expected for combustion processes. The demonstrated instrumental capabilities are appropriate for measuring changes in O2 mole fraction in background air which could be of importance to a broad range of biogeochemical studies.

Using the four-times daily and monthly-mean reanalysis datasets of NCEP/NCAR for the 1958 to 2018 period, we investigate the interannual variability of the June-July-August (JJA)–mean water vapor source and sink over the tropical eastern Indian Ocean-Western Pacific (TEIOWP) and the underlying mechanism. It is found that the two major modes (EOF1 and EOF2) of the water vapor source and sink anomalies over the TEIOWP present a southwest-northeast oriented dipole and a southwest-northeast oriented tripole. Specifically, when the western maritime continent shows an anomalous water vapor source, the northwestern Pacific is characterized by anomalous water vapor sink and source in EOF1 and EOF2 modes, respectively. The EOF1 and EOF2 modes are primarily driven by a single and a double meridional cell anomaly, which corresponds to the in-phase and out-of-phase linkage between evaporation anomalies over the western maritime continent and precipitation anomalies over the northwestern Pacific, respectively. Furthermore, the EOF1 mode is regulated by the quick transition of the El Niño-Southern Oscillation (ENSO) phase, whereas the EOF2 mode probably originates from internal atmospheric variability. Considering that the standard deviation of PC1 is much higher during ENSO years than that during non-ENSO years, it is probable that the water source and sink anomalies over the TEIOWP tend to be dominant by EOF1 mode during ENSO years. In contrast, the EOF2 mode may play an important role in the water source and sink anomalies over the TEIOWP during non-ENSO years. Accordingly, the water vapor source and sink anomalies over the TEIOWP may be well predicted based on the ENSO state in the previous December-January-February. These results are useful for understanding the predictability of water vapor source and sink anomalies over the TEIOWP.

<div class="htmlview paragraph">This paper reviews the recent G189A computer program developments in the area of humidity control for the U.S. Lab Module in the Space Station. The humidity control function is provided as an indirect or passive function by the Common Cabin Air Assemblies (CCAA) in pressurized elements or modules in the Space Station. The CCAAs provide active cabin temperature control through implementation of a digital/electromechanical control system (i.e., a proportional/integral (PI) control system). A selected cabin temperature can be achieved by this control system as long as the sensible and latent heat loads are within specified limits.</div> <div class="htmlview paragraph">In this paper three pertinent analytical cases directed to determining minimum or maximum dew point temperatures are discussed. In these cases the basic sensible heat loads are set at constant values. The sources of water vapor in the module include: 1) the crew activity timeline with variations in metabolic heat load, 2) the cyclic operation of the Carbon Dioxide Removal Assembly (CDRA) which alternately removes water vapor from the cabin (along with CO<sub>2</sub>) at a steady rate and subsequently returns water vapor to the cabin as a pulse, 3) operation of Crew Systems equipment (such as the handwash facility or the shower) on its timelines. Since the sources of water vapor are all time varying, it is evident that the issue of extreme cabin dew point temperatures requires a transient analysis.</div> <div class="htmlview paragraph">Prior to discussing the three analytical cases considered here, discussions of the operations and of the thermodynamic principles involved in the performance of the CCAA and the CDRA are included. Also, the interactions of the CDRA and CCAA are discussed. The results of the three analytical cases are presented. It is shown that for the present design performance modeling and data for the CCAA and the CDRA and the sensible and latent loads imposed on the system considered here the specified minimum and maximum limits on cabin humidity can be accommodated.</div> <div class="htmlview paragraph">©1994. The Boeing Company. All rights reserved. This work performed under contract for NASA.</div> <div class="htmlview paragraph">The Space Station requirement that the Environmental Control and Life Support System (ECLSS) equipment and other equipment be capable of surviving a laboratory module depressurization/repressurization event must be dealt with analytically. The depressurization process includes condensation of water vapor followed by freezing. These change-of-phase processes have been included in the G189A program's simulation logic. An example analysis of a Lab Module depressurization event has been run and the results are included here. The condensation and freezing effects are noted.</div>

Using automatic rainfall station and ERA5 reanalysis data, the Southwest China vortex (SWCV) processes that induce warm-sector rainstorms in the Sichuan Basin were analyzed, their environmental field and dynamic thermal characteristics were researched through physical diagnosis and dynamic synthesis, and the development mechanism was discussed. The results showed that for the warm-sector rainstorms caused by the SWCV (SWCV-WR), the general circulation backgrounds can could be divided into three types: upper trough-vortex (Type I), plateau shear line (Type II), and short-wave trough (Type III) types. Regarding the aspects of the maintenance of the SWCV, duration of the warm-sector rainstorms, and maximum hourly precipitation intensity, the influence of Type I is the most evident, followed by Types II and III for SWCV-WR. The vertical structure of the SWCV is shallow and inclined to the west with height, but the positive vorticity of Types I and II can reach up to 200 hPa for SWCV-WR. The pseudo-equivalent potential temperature in the vortex area is greater than 354 K, which is accompanied by an upward-energy tongue, and shallow secondary circulation occurs on the eastern side of the SWCV, promoting vortex development. Regarding the thermodynamic characteristics of SWCV, Type I is the strongest, followed by Type III, and Type II is the weakest. The water vapor supply in different types of SWCV-WR is not only closely related to the strength of water vapor transport in the Bay of Bengal, but also to the variations in water vapor transport caused by the influence of different water vapor sources, such as the South China Sea and western Pacific Ocean, during its transportation. For SWCV-WR, the vorticity advection presents an uneven east-west positive and negative distribution. Under the dynamic forcing, the positive vorticity on the east side of SWCV of Types I and II (III) is enhanced (weakened), while that on the west side is weakened (enhanced). Different atmospheric vorticity variations have different significant effects on the three types of SWCV-WR. Under the spatial non-uniform heating, the horizontal non-uniform heating effect on the different types of SWCV-WR has regional differences, while the vertical non-uniform heating effect has the largest effect on the spatial non-uniform heating and a positive heating effect on the three types of SWCV-WR. Therefore, the spatial non-adiabatic heating effect, particularly the vertical non-uniform heating effect, is an important mechanism for the development and evolution of SWCV and SWCV-WR.

North China experienced an extreme precipitation event from July 29 to August 1, 2023 (i.e., the “23.7” event) causing severe floods, significant infrastructure damage and multiple fatalities. To enhance comprehension of the mechanism behind the extreme precipitation of the “23.7” event, water vapor transport paths and sources were determined, and water vapor contribution of each source was quantitatively evaluated based on Lagrangian methods. Results showed that the extreme precipitation of the “23.7” event was closely related to large‐scale water vapor transport and convergence from low‐latitude oceans. There were five main water vapor sources which corresponded to five transport pathways. Path 1 was derived from tropical West Pacific, containing the most trajectories (195), carrying the most water vapor (69.3%) and contributing the most to the extreme precipitation of the “23.7” event (45.7%). Path 2 was guided by the cross‐equatorial flow through South China Sea, contributing to 10.1% of the precipitation. Path 3 originating from eastern tropical Indian Ocean and Path 4 from the west source near the Caspian Sea contributed less to the precipitation. Last but not the least, water vapor evaporation from eastern China contributed more than 30% to the extreme precipitation, making this region another important water vapor source.

This paper provides calculated values of specific enthalpy, specific entropy and specific Gibbs energy associated with moist hydrogen and air. They cover the range of interest in humidity control and measurement methods for fuel cell applications from water vapor content of dew-point temperatures 60 {degree sign}C to 200 {degree sign}C with absolute pressures of 0.1 MPa, 0.5 MPa, 1 MPa and 2 MPa. Molar enthalpy, molar entropy and molar Gibbs free energy of moist hydrogen and air are expressed explicitly in terms of the associated water vapor density. The values of the molar quantities are the sum of three parts due to: 1. The mole fraction of water vapor in a gas mixture; 2. The mole fraction of dry hydrogen or dry air in a gas mixture ; and 3. The effects of interaction between water molecules and hydrogen as well as air molecules.

The aim of this paper is to investigate the climate water-vapor sources of Xinjiang region and their shifts during the past 20 years. First, the principle and steps are roughly regulated to seek the water-vapor sources. Second, the climate stationary water-vapor transport in troposphere is calculated to distinguish where the water vapor comes from by ERA-40 reanalysis. In addition, the collocation between the transport and the atmospheric column water vapor content is analyzed. The results show that the major vapor comes from the west side of Xinjiang for mid-month of seasons, apart from July while the water vapor comes from the north or northwest direction. The water vapor sources are different for different seasons, for example the Caspian Sea and Mediterranean are the sources in January and April, the North Atlantic and the Arctic sea in July and the Black Sea and Caspian Sea in October, respectively. In recent ten years more water vapor above Xinjiang comes from the high latitudes and the Arctic sea with global warming, and less from Mediterranean in comparison with the case of 1973–1986. In fact, the air over subtropics becomes dry and the anomalous water vapor transport direction turns to west or southwest during 1987–2000. By contrast, the air over middle and high latitudes is warmer and wetter than 14 years ago.

The climatological characteristics of water vapor transport over the Tibetan Plateau (TP) were investigated in this study by using the ERA-interim and JRA55 monthly reanalysis dataset. The trends of water vapor budget and water vapor sources during the past 40 years were also revealed. The analyses show that the TP is a water vapor convergence area, where the convergence was enhanced from 1979 to 2018. In addition, the convergence is much stronger in JJA, with a linear trend that is twice the annual average trend. The climatological water vapor sources over the TP were identified mainly at the southern and western boundaries, with the vapor sources at the southern boundaries originating from the Arabian Sea and Bay of Bengal and the vapor sources at the western boundary being transported by mid-latitude westerlies. The TP is a moisture sink at a climatological mean, with an annual average net water vapor flux of 11.86 × 106kg ∙ s−1. Water vapor transport is much stronger in JJA than in other times of the year, and the net water vapor flux is 29.60 × 106kg ∙ s−1. The net water vapor flux in the TP increased with a linear trend of 0.12×106kg ∙ s−1 ∙ year−1 (α = 0.01), while the increase in the flux was more significant in JJA than in other times of the year with a linear trend of 0.30 ×106kg ∙ s−1 ∙ year−1 (α = 0.01). Detailed features in the water vapor flux and transport changes across the TP’s four boundaries were explored by simulating backward trajectories with a Lagrangian trajectory model (hybrid single-particle Lagrangian integrated trajectory model, HYSPLIT). In the study period, the water vapor contribution rate of western channel is increased. However, the Southern channel’s water vapor contribution decreased.

Deuterium excess and stable oxygen isotopes in precipitation have been widely applied to trace the source of water vapor. In this study, hydrogen and oxygen isotope analyses of samples were collected on seven sampling stations in Dingxi area from April 2019 to April 2020. The seasonal variation of hydrogen and oxygen stable isotopes as well as the d-excess indicate that the source of water vapor in Dingxi area is mostly from a single source. However, there are different sources of water vapor in the summer. Meanwhile, water vapor sources were analyzed using the Lagrange algorithm, indicating two different principal water vapor sources for precipitation in the area: some locally recycled water vapor in summer and autumn, and most water vapor from the westerly belt. Further studies using the PSCF and CWT analysis methods show that the locally recycled water vapor contributes more to its precipitation in the northwest of Dingxi area.

Atmospheric water vapor plays an important role in the water cycle, especially in arid Central Asia, where precipitation is invaluable to water resources. Understanding and quantifying the relationship between water vapor source regions and precipitation is a key problem in water resource research in typical arid Central Asia, Northern Xinjiang. However, the relationship between precipitation and water vapor sources is still unclear of snow season. This paper aimed at studying the role of water vapor source supply in the Northern Xinjiang precipitation trend, which was investigated using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The results showed that the total water vapor contributed from Western Eurasia and the North Polar area presented upward trends similar to the precipitation change trend, which indicated that the water vapor contribution from the two previous water vapor source regions supplied abundant water vapor and maintained the upward precipitation trend from 1980 to 2017 in Northern Xinjiang. From the climatology of water vapor transport, the region was controlled by midlatitude westerlies and major water vapor input from the western boundary, and the net water vapor flux of this region also showed an annual increasing trend. Western Eurasia had the largest moisture percentage contribution to Northern Xinjiang (48.11%) over the past 38 years. Northern Xinjiang precipitation was correlated with water vapor from Western Eurasia, the North Polar area, and Siberia, and the correlation coefficients were 0.66, 0.45, and 0.57, respectively. These results could aid in better understanding the water cycle process and climate change in this typical arid region of Central Asia.

A redetermination of the argon mole fraction in air has been undertaken in two samples of dried natural air using mass spectrometric analysis with reference to a suite of gravimetrically prepared synthetic dry air mixtures. The resulting measurement of the argon mole fraction was 9.332 mmol mol−1 with a combined standard uncertainty of 3 µmol mol−1. This is significantly different from the value, 9.17 mmol mol−1, conventionally employed in the CIPM formula for the determination of the density of moist air during mass standard comparisons. Using the presently reported argon mole fraction value in the CIPM formula rather than the conventional value removes the recently identified discrepancy between the two methods of determining the density of moist air during mass standard comparisons: the CIPM formula method and the air buoyancy artefacts method. Nitrogen, oxygen and carbon dioxide mole fractions in the dry air samples were obtained simultaneously.