Water Vapour
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2022 ◽  
Vol 26 (1) ◽  
pp. 91-116
Andreas Riedl ◽  
Yafei Li ◽  
Jon Eugster ◽  
Nina Buchmann ◽  
Werner Eugster

Abstract. Non-rainfall water (NRW), defined here as dew, hoar frost, fog, rime, and water vapour adsorption, might be a relevant water source for ecosystems, especially during summer drought periods. These water inputs are often not considered in ecohydrological studies, because water amounts of NRW events are rather small and therefore difficult to measure. Here we present a novel micro-lysimeter (ML) system and its application which allows us to quantify very small water inputs from NRW during rain-free periods with an unprecedented high accuracy of ±0.25 g, which corresponds to ±0.005 mm water input. This is possible with an improved ML design paired with individual ML calibrations in combination with high-frequency measurements at 3.3 Hz and an efficient low-pass filtering to reduce noise level. With a set of ancillary sensors, the ML system furthermore allows differentiation between different types of NRW inputs, i.e. dew, hoar frost, fog, rime, and the combinations among these, but also additional events when condensation on leaves is less probable, such as water vapour adsorption events. In addition, our ML system design allows one to minimize deviations from natural conditions in terms of canopy and soil temperatures, plant growth, and soil moisture. This is found to be a crucial aspect for obtaining realistic NRW measurements in short-statured grasslands. Soil temperatures were higher in the ML compared to the control, and thus further studies should focus on improving the thermal soil regime of ML. Our ML system has proven to be useful for high-accuracy, long-term measurements of NRW on short-statured vegetation-like grasslands. Measurements with the ML system at a field site in Switzerland showed that NRW input occurred frequently, with 127 events over 12 months with a total NRW input of 15.9 mm. Drainage-water flow of the ML was not measured, and therefore the NRW inputs might be conservative estimates. High average monthly NRW inputs were measured during summer months, suggesting a high ecohydrological relevance of NRW inputs for temperate grasslands.

2022 ◽  
Vol 52 (4) ◽  
pp. 727-732
Y. E. A. RAJ

The Tiros Operational Vertical Sounder (TOVS) is a popular satellite sounding system. In this paper certain features of Indian northeast monsoon have been studied with the help of three years of TOVS data received through the satellite ground station located at the Regional Meteorological Centre, Chennai. The TOVS based latitudinal and longitudinal profiles of Outgoing Longwave Radiation (OLR) and Precipitable Water Vapour (PWV) were derived for various phases of northeast monsoon activity, over coastal and interior Tamilnadu and oceanic regions. These were consistent with the known spatial rainfall characteristics of northeast monsoon. The average vertical temperature profiles derived for the various phases of northeast monsoon for the different regions revealed that the lowest layer and upper troposphere are warmer and mid troposphere colder during active northeast monsoon compared to dry phase. The diurnal variation of OLR and PWV and the comparability of TOVS derived data with conventional upper air data and INSAT data have been briefly discussed.

Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 105
Ibrahim Al-Helal ◽  
Abdullah Alsadon ◽  
Samy Marey ◽  
Abdullah Ibrahim ◽  
Mohamed Shady ◽  

In arid regions, drastic seasonal variations in the climatic parameters are common; thus, a high potential of geothermal effects for heating/cooling applications is expected. However, such applications are very limited in these regions due to the lack of information about underground temperature profiles of the surface and shallow zones. Therefore, this study aims to (i) measure the underground temperature profile for one year to determine the optimum depth for burying EAHE pipes; (ii) examine the possibility of water vapour condensation occurring in the buried EAHE pipes, if the air let into the pipes was humid; and (iii) quantify the maximum cooling/heating capacity, if an EAHE was implemented. The results show that a 3-meter depth is optimal to bury EAHE pipes, where the ground temperature is 32 °C in the summer and 29 °C in the winter. These temperatures would provide a maximum cooling/heating capacity of 1000/890 MJ day−1 for each 1 m3 of humid air exhausted from a greenhouse. If the EAHE were to operate in a closed loop with a greenhouse, the condensation of water vapour in the EAHE pipes would be impossible during the cooling process. The results of this study are useful for designers using geothermal effects for indoor space cooling and heating in arid regions.

2022 ◽  
Ruping Mo ◽  
Hai Lin ◽  
Frédéric Vitart

Abstract Atmospheric rivers (ARs) are long and narrow bands of enhanced water vapour flux concentrated in the lower troposphere. Many studies have documented the important role of cold-season ARs in producing heavy precipitation and triggering extreme flooding in many parts of the world. However, relatively little research has been conducted on the warm-season ARs and their impacts on extreme heatwave development. Here we show an anomalous warm-season AR moving across the North Pacific and its interaction with the western North American heatwave in late June 2021. We call it an “oriental express’’ to highlight its capability to transport tropical moisture to the west coast of North America from sources in Southeast Asia. Its landfall over the Alaska Panhandle lasted for more than two days and resulted in significant spillover of moisture into western Canada. We provide evidence that the injected water vapour was trapped under the heat dome and may have formed a positive feedback mechanism to regulate the heatwave development in western North America.

Ferhat Benmahiddine ◽  
Rafik Belarbi

Hemp concrete is one of the most used bio-based materials in the construction industry due to its hygrothermal behaviour and its low environmental footprint. This is mainly due to the complexity of the microstructure of these materials and their highly breathable nature. However, their use remains limited due to the lack of databases and guarantees regarding of the evolution of their functional properties over time. In this paper, experimental investigation has been performed to answer this problematic. The aim is to investigate the influence of accelerated aging on the properties of this material through a succession of immersion/freezing/drying cycles. Materials (aged and reference) were characterized at the same relative humidity state in order to be able to compare the results and to highlight the effect of ageing on the properties of hemp concrete. Results revealed a significant change in the microstructure of this material. As a consequence, this induced significant changes in its hygrothermal and mechanical properties. An increase of 40% in water vapour permeability and decrease of 57% in compressive strength were observed after aging (07 cycles of immersion/freezing/drying).

2022 ◽  
Vol 15 (1) ◽  
pp. 117-129
Mark T. Richardson ◽  
David R. Thompson ◽  
Marcin J. Kurowski ◽  
Matthew D. Lebsock

Abstract. Upcoming spaceborne imaging spectrometers will retrieve clear-sky total column water vapour (TCWV) over land at a horizontal resolution of 30–80 m. Here we show how to obtain, from these retrievals, exponents describing the power-law scaling of sub-kilometre horizontal variability in clear-sky bulk planetary boundary layer (PBL) water vapour (q) accounting for realistic non-vertical sunlight paths. We trace direct solar beam paths through large eddy simulations (LES) of shallow convective PBLs and show that retrieved 2-D water vapour fields are “smeared” in the direction of the solar azimuth. This changes the horizontal spatial scaling of the field primarily in that direction, and we address this by calculating exponents perpendicular to the solar azimuth, that is to say flying “across” the sunlight path rather than “towards” or “away” from the Sun. Across 23 LES snapshots, at solar zenith angle SZA = 60∘ the mean bias in calculated exponent is 38 ± 12 % (95 % range) along the solar azimuth, while following our strategy it is 3 ± 9 % and no longer significant. Both bias and root-mean-square error decrease with lower SZA. We include retrieval errors from several sources, including (1) the Earth Surface Mineral Dust Source Investigation (EMIT) instrument noise model, (2) requisite assumptions about the atmospheric thermodynamic profile, and (3) spatially nonuniform aerosol distributions. By only considering the direct beam, we neglect 3-D radiative effects such as light scattered into the field of view by nearby clouds. However, our proposed technique is necessary to counteract the direct-path effect of solar geometries and obtain unique information about sub-kilometre PBL q scaling from upcoming spaceborne spectrometer missions.

Anže Prašnikar ◽  
Blaž Likozar

To reduce CO2 emissions, a flexible process operation for chemical methanol synthesis may be required as the supply of renewable energy-based feedstocks fluctuates. Determining the changing conditions’ analysis for the...

2022 ◽  
Vol 44 (3) ◽  
pp. 243-248

Integrated atmospheric water vapour content. has been evaluated from the spectral optical depths around the PaT band of water vapour by making directly transmitted solar flux measurements at 800, 935 and 1025 nm. The temporal variation of the total precipitable water vapour shows significant seasonal variation with maximum during~ pre-monsoon and monsoon months and minimum during winter months. The integrated content shows a positive correlation with surface humidity parameters and the correlation is better during monsoon months compared to other seasons. The experimentally derived variations of water vapour are compared with the model variations formulated using radiosonde data. The aerosol extinctions derived from the, multi-spectral solar flux measurements in the visible and near IR regions increase with increasing atmospheric water vapour and this increase shows .a seasonal dependence the surface temperature also seems to affect the, aerosol extinction probably through Its effect on the mixing heights.

2022 ◽  
Vol 45 (4) ◽  
pp. 372-376

2022 ◽  
Vol 334 ◽  
pp. 06005
Paolo Piccardo ◽  
Roberto Spotorno ◽  
Valeria Bongiorno ◽  
Daniele Paravidino ◽  
Christian Geipel ◽  

An SOFC stack operated for 40,000 hours has been dismantled offering the opportunity to characterize the metallic interconnect. The metal plate was carefully investigated to define the evolution of the surfaces exposed to the air and to the hydrogen electrodes respectively. The observations of the surfaces reveal the stability of the layers applied on top of the rib at the air side while in the bottom of the channels the protective coating (i.e., Co-Mn base spinel oxide) shows large crystals. The cross section allowed to highlight the formation of a rather homogeneous layer of thermal grown oxide between the metal and the coating. The average thickness of the TGO is around 11 μm. The hydrogen side shows a superficial alteration (due to the interaction with the water vapour) changing from the inlet to the outlet where it seems thinner as if the TGO further reacted by forming volatile compounds. The cross section observations confirmed the presence of a porous TGO with a rather high content of manganese in a Cr-Mn spinel oxide. Several spots testifies the zones of contact with the Ni base contacting layer. The cross section corresponding to such zones highlighted the Ni diffusion in the metal substrate.

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