potential evaporation
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Author(s):  
Andrey D. PLOTNIKOV ◽  
Aleksandr V. VODOLAZHSKIY ◽  
Natalya S. YAKUPOVA

The paper represents requirements for cryogenic grease lubricants used in the rocket and space technology. Data on lubricants based on perfluoropolyether liquid FEN is provided. New lubricant testing methods enabling to analyze their chemical composition and low-temperature characteristics are proposed. Quoted are investigation results for the equivalents of previously used cryogenic lubricants NIKA, NIRA and «Ametist». A practical relevance of the paper has been proven by introduction of low-temperature lubricants «Sever» currently being used in rocket and space items, as well аs successful application of the developed lubricant incoming inspection procedures at RSC Energia. Key words: low-temperature lubricant, perfluoropolyether liquid FEN, viscosity, solidification temperature, IR spectrum, potential evaporation.


MAUSAM ◽  
2021 ◽  
Vol 47 (1) ◽  
pp. 99-100
Author(s):  
N. N. SRIVASTAVA ◽  
U. S. VICTOR ◽  
P. VIJAYA KUMAR ◽  
B. V. RAMANA RAO

2021 ◽  
Author(s):  
Vadim Yurevich Grigorev ◽  
Maxim A. Kharlamov ◽  
Natalia K. Semenova ◽  
Sergey R. Chalov ◽  
Alexey A. Sazonov

Abstract Water level and distribution of dissolved and suspended matter of Lake Baikal are strongly affected by river inflow during rain-driven floods. This study analyses river flow changes at 44 streamflow gauges and related precipitation, evaporation, potential evaporation and soil moisture obtained from ERA5-Land dataset. Based on Sen-Slope trend estimator, Mann–Kendall non-parametric test, and using dominant analyses we estimated influence of meteorological parameters on river flow during 1979-2019. Using ridge-regression we found significant relationships between precipitation elasticity of river flow and catchments features. Half of the gauges in eastern part of Selenga river basin showed a significant decreasing trend of average and maximum river flow (up to -2.9%/year). No changes in central volume date of flood flow have been found. A reduction in rainfall amounts explains more than 60% of runoff decline. Decrease in evaporation is observed where precipitation decrease is 0.8%/y or more. Catchments where the precipitation trends are not as substantial are associated with increasing evaporation as a result of the increase of potential evaporation. Negative trends of precipitation are accompanied by negative trends of soil moisture. Finally, the study reveals sensitivity of the catchments with steep slopes in humid area to precipitation change.


2021 ◽  
Author(s):  
Hassan Al-Najjar ◽  
Gokmen Ceribasi ◽  
Emrah Dogan ◽  
Khalid Qahman ◽  
Mazen Abualtayef ◽  
...  

Abstract The water supply in the Gaza Strip substantially depends on the groundwater resource of the Gaza coastal aquifer. The climate changes and the over-exploiting processes negatively impact the recovery of the groundwater balance. The climate variability is characterized by the decline in the precipitation by −5.2% and an increase in the temperature by +1 °C in the timeframe of 2020–2040. The potential evaporation and the sunshine period are expected to increase by about 111 mm and 5 hours, respectively, during the next 20 years. However, the atmosphere is predicted to be drier where the relative humidity will fall by a trend of −8% in 20 years. The groundwater abstraction is predicted to increase by 55% by 2040. The response of the groundwater level to climate change and groundwater pumping was evaluated using a model of a 20-neuron ANN with a performance of the correlation coefficient (r)=0.95–0.99 and the root mean square error (RMSE)=0.09–0.21. Nowadays, the model reveals that the groundwater level ranges between −0.38 and −18.5 m and by 2040 it is expected to reach −1.13 and −28 m below MSL at the northern and southern governorates of the Gaza Strip, respectively.


Author(s):  
Tsuneo Kuwagata ◽  
Mari Murai-Hatano ◽  
Maya Matsunami ◽  
Shingo Terui ◽  
Atsushi J. Nagano ◽  
...  

Buildings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 476
Author(s):  
Aytaç Kubilay ◽  
John Bourcet ◽  
Jessica Gravel ◽  
Xiaohai Zhou ◽  
Travis V. Moore ◽  
...  

Parts of the building envelope that frequently receive high amounts of rain are usually exposed to a higher risk of deterioration due to moisture. Determination of such locations can thus help with the assessment of moisture-induced damage risks. This study performs computational fluid dynamics (CFD) simulations of wind-driven rain (WDR) on the Parliament buildings in Ottawa, Canada. Long-term time-varying wetting load due to WDR and potential evaporation are considered according to several years of meteorological data, and this cumulative assessment is proposed as a fast method to identify critical locations and periods. The results show that, on the Center Block of the Parliament buildings, the façades of lower towers facing east are the most exposed to WDR, together with the corners of the main tower. Periods of high WDR wetting load larger than the potential evaporation are observed, indicating that deposited rain may lead to moisture accumulation in the envelope. During these critical periods of up to several months, air temperature may repeatedly drop below freezing point, which poses a risk of freeze–thaw damage. First assessment on future freeze–thaw damage risks indicates an increase in such risks at moderate increases in temperature, but a lower risk is found for larger increases in temperature.


Author(s):  
Mark R. Jury

Abstract The eastward shift of semi-arid climate across South Africa is studied using satellite assimilated cloud cover, vegetation temperature and potential evaporation 1981–2019, and 21st century coupled model projections. Semi-arid thresholds over the plateau have shifted hundreds of kilometers eastward in the Vaal River catchment for potential evaporation, cloud fraction, and vegetation temperature. Coastal cloudiness has also changed due to sea breezes modified by shelf zone sea temperatures. Processes underlying the spread of semi-arid conditions across South Africa are quantified. Desiccation is related to greater westerly airflow, as the atmospheric boundary layer over the Kalahari preferentially links with the upper-level circulation. Warm dry spells and climate change enhance the meridional temperature gradient and accelerate the sub-tropical jet at both short- and long timescales. According to observations and reanalysis, dry westerlies prevail during the afternoon and induce +0.2 °C/year trends in vegetation temperature over the Highveld during the study period. Coupled model projections show that semi-arid conditions expand eastward from Bloemhof (25.5°E) by 50,000 km2, altering future adaptation strategies.


2021 ◽  
Author(s):  
Thibault Lemaitre-Basset ◽  
Ludovic Oudin ◽  
Guillaume Thirel ◽  
Lila Collet

Abstract. The increasing air temperature in a changing climate will impact actual evaporation and have consequences for water resources management in energy-limited regions. In many hydrological models, evaporation is assessed by a preliminary computation of potential evaporation (PE) representing the evaporative demand of the atmosphere. Therefore, in impact studies the quantification of uncertainties related to PE estimation, which can arise from different sources, is crucial. Indeed, a myriad of PE formulations exist and the uncertainties related to climate variables cascade into PE computation. So far, no consensus has emerged on the main source of uncertainty in the PE modelling chain for hydrological studies. In this study, we address this issue by setting up a multi-model and multi-scenario approach. We used seven different PE formulations and a set of 30 climate projections to calculate changes in PE. To estimate the uncertainties related to each step of the PE calculation process (namely Representative Concentration Pathways, General Circulation Models, Regional Climate Models and PE formulations), an analysis of variance decomposition (ANOVA) was used. Results show that PE would increase across France by the end of the century, from +40 to +130 mm/year. In ascending order, uncertainty contributions by the end of the century are explained by: PE formulations (below 10 %), then RCPs (above 20 %), RCMs (30–40 %) and GCMs (30–40 %). Finally, all PE formulations show similar future trends since climatic variables are co-dependent to temperature. While no PE formulation stands out from the others, in hydrological impact studies the Penman-Monteith formulation may be preferred as it is representative of the PE formulations ensemble mean and allows accounting for climate and environmental drivers co-evolution.


Land ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 612
Author(s):  
Guangxing Ji ◽  
Huiyun Song ◽  
Hejie Wei ◽  
Leying Wu

Analyzing the temporal variation of runoff and vegetation and quantifying the impact of anthropic factors and climate change on vegetation and runoff variation in the source area of the Yangtze River (SAYR), is of great significance for the scientific response to the ecological protection of the region. Therefore, the Budyko hypothesis method and multiple linear regression method were used to quantitatively calculate the contribution rates of climate change and anthropic factors to runoff and vegetation change in the SAYR. It was found that: (1) The runoff, NDVI, precipitation, and potential evaporation in the SAYR from 1982 to 2016 all showed an increasing trend. (2) The mutation year of runoff data from 1982 to 2016 in the SAYR is 2004, and the mutation year of NDVI data from 1982 to 2016 in the SAYR is 1998. (3) The contribution rates of precipitation, potential evaporation and anthropic factors to runoff change of the SAYR are 75.98%, −9.35%, and 33.37%, respectively. (4) The contribution rates of climatic factors and anthropic factors to vegetation change of the SAYR are 38.56% and 61.44%, respectively.


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