scholarly journals Isoscape of δ18O in Precipitation of the Qinghai-Tibet Plateau: Assessment and Improvement

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3392
Author(s):  
Yudong Shi ◽  
Shengjie Wang ◽  
Mingjun Zhang ◽  
Athanassios A. Argiriou ◽  
Rong Guo ◽  
...  
Keyword(s):  
Meteorological Data ◽  
Fuzzy Cluster ◽  
Tibet Plateau ◽  
Cluster Method ◽  
Water Isotopes ◽  
Stable Water Isotopes ◽  
Monthly Basis ◽  
Seasonal Movement ◽  
Qinghai Tibet Plateau ◽  
Fuzzy Cluster Method

The spatial distribution of stable water isotopes (also known as an isoscape) in precipitation has drawn increasing attention during the recent years. In this study, based on the observations at 32 stations, we assessed two widely applied global isoscape products (Regionalized Cluster-based Water Isotope Prediction (RCWIP) and Online Isotopes in Precipitation Calculator (OIPC)) at the Qinghai-Tibet Plateau (QTP) and then established an improved isoscape of oxygen isotopes in precipitation on a monthly basis using a regionalized fuzzy cluster method. Two fuzzy clusters can be determined, which is consistent using three meteorological data. The monthly isoscapes show the seasonal movement of high and low isotopic value regions across the QTP and reveal the influences of monsoon and westerly moisture. According to the cross validation, the δ18O in precipitation in the new monthly isoscapes for the QTP we propose performs better compared to the existing global products. To create a regional isoscape in many other regions, the regionalized fuzzy cluster method can be considered especially for regions with complex controlling regimes of precipitation isotopes.

A fuzzy cluster method for turbulent/non-turbulent interface detection

2021 ◽  
Vol 62 (4) ◽  
Author(s):  
Khaled Younes ◽  
Bradley Gibeau ◽  
Sina Ghaemi ◽  
Jean-Pierre Hickey
Keyword(s):  
Fuzzy Cluster ◽  
Cluster Method ◽  
Fuzzy Cluster Method

Classification of Wear Debris Using Weighted Fuzzy Cluster Method

2010 ◽  
Vol 33 ◽  
pp. 70-73
Author(s):  
Dai Qiang Peng ◽  
Feng Xu
Keyword(s):  
Wear Debris ◽  
Wear Particle ◽  
Fuzzy Cluster ◽  
Cluster Method ◽  
Wear Particles ◽  
Machine Condition ◽  
Machine Condition Monitoring ◽  
Fuzzy Cluster Method ◽  
The Membership Function

The analysis and identification of wear particles for machine condition monitoring is usually very time-consuming by experienced inspectors. In order to remedy the limitation, automation of the analysis procedure appears to be necessary. A novel weighted fuzzy c-means algorithm for wear particle classification is proposed in this paper. The algorithm uses the variation of the pixel intensities of a region to choose strong resembling area. Then, the spatial relationships of the membership function are constructed to regulate the pixel membership obtained from the FCM object function. Finally, wear debris are classified based on the fuzzy membership. The example shows that the method is briefly and effectively.

scholarly journals The Impact of Climate Change on the Surface Albedo over the Qinghai-Tibet Plateau

2021 ◽  
Vol 13 (12) ◽  
pp. 2336
Author(s):  
Chaonan Chen ◽  
Li Tian ◽  
Lianqi Zhu ◽  
Yuanke Zhou
Keyword(s):  
Climate Change ◽  
Solar Radiation ◽  
Land Surface ◽  
Meteorological Data ◽  
Growing Season ◽  
High Elevation ◽  
Tibet Plateau ◽  
Decrease Rate ◽  
The Impact ◽  
Qinghai Tibet Plateau

Albedo is a characterization of the Earth’s surface ability to reflect solar radiation, and control the amount of solar radiation absorbed by the land surface. Within the context of global warming, the temporal and spatial changes of the albedo and its response to climate factors remain unclear. Based on MCD43A3 (V005) albedo and meteorological data (i.e., temperature and precipitation), we analyzed the spatiotemporal variations of albedo (2000–2016) and its responses to climate change during the growing season on the Qinghai-Tibet Plateau (QTP). The results indicated an overall downward trend in the annual albedo during the growing season, the decrease rate was 0.25%/decade, and the monthly albedo showed a similar trend, especially in May, when the decrease rate was 0.53%/decade. The changes also showed regional variations, such as for the annual albedo, the areas with significant decrease and increase in albedo were 181.52 × 103 km2 (13.10%) and 48.82 × 103 km2 (3.52%), respectively, and the intensity of albedo changes in low-elevation areas was more pronounced than in high-elevation areas. In addition, the annual albedo-temperature/precipitation relationships clearly differed at different elevations. The albedo below 2000 m and at 5000–6000 m was mainly negatively correlated with temperature, while at 2000–4000 m it was mainly negatively correlated with precipitation. The contemporaneous temperature could negatively impact the monthly albedo in significant ways at the beginning of the growing season (May and June), whereas in the middle of the growing season (July and August), the albedo was mainly negatively correlated with precipitation, and at the end of the growing season (September), the albedo showed a weak correlation with temperature/precipitation.

scholarly journals Stable Isotope Reveals Tap Water Source under Different Water Supply Modes in the Eastern Margin of the Qinghai–Tibet Plateau

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2578
Author(s):  
Mingxia Du ◽  
Mingjun Zhang ◽  
Shengjie Wang ◽  
Hongfei Meng ◽  
Cunwei Che ◽  
...  
Keyword(s):  
Surface Water ◽  
Water Supply ◽  
Water Samples ◽  
Tap Water ◽  
Water Source ◽  
Water Sources ◽  
Tibet Plateau ◽  
Water Isotopes ◽  
Source Water ◽  
Qinghai Tibet Plateau

Based on 1260 tap water samples gathered monthly and 136 surface water samples collected seasonally in the eastern margin of the Qinghai–Tibet Plateau, the local tap water line, the basic spatiotemporal characteristics of tap water isotopes, and their indication for water source under different water supply modes were discussed, linking the local tap water supply and water source information. A new tap water isotopes data set based on dense sampling sites was established, which was reliable for the analysis of tap water isotope features, tap water supply management, and tap water sources. The main conclusions are: (1) The local tap water lines in Gannan and Longnan are δ2H = (7.06 ± 0.17) δ18O + (3.24 ± 1.75) (r2 = 0.81, p < 0.01) and δ2H = (5.66 ± 0.09) δ18O + (−8.12 ± 0.82) (r2 = 0.82, p < 0.01), respectively. (2) The annual mean δ2H and δ18O in tap water show an increasing trend from southwest to northeast. The seasonal differences of δ2H and δ18O in tap water in Gannan and Longnan are small. (3) The correlation of tap water isotopes with those in main source water is high, while that of isotopes in tap water with those in non-water source is low. Under the central water supply mode by local tap water company, tap water isotopes in Gannan where groundwater is the direct water source show weak connection with those in surface water and precipitation, and those in tap water in Longnan with surface water as main source water reveal good connection with isotopes in surface water. Under mixed water supply modes, tap water isotopes indicate that surface water is the main tap water source in Gannan and Longnan with multiple water sources.

scholarly journals Permafrost, active layer and meteorological data (2010–2020) from a relict permafrost site at Mahan Mountain, Northeast of Qinghai-Tibet Plateau

2021 ◽  
Author(s):  
Tonghua Wu ◽  
Changwei Xie ◽  
Xiaofan Zhu ◽  
Jie Chen ◽  
Wu Wang ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Active Layer ◽  
Thermal State ◽  
Meteorological Data ◽  
Water Vapor Pressure ◽  
Ground Temperature ◽  
Tibet Plateau ◽  
Different Depths ◽  
Qinghai Tibet Plateau

Abstract. Relict permafrost presents an ideal opportunity to understand the impacts of climatic warming on the ground thermal regime since it is characterized by mean annual ground temperature close to 0 °C and relatively thin permafrost. The long-term and continuous observations of permafrost thermal state and climate background are of great importance to reveal the links between the energy balance on hourly to annual timescales, to evaluate the variations of permafrost thermal state over multi-annual periods and to validate the remote sensing dataset. Until now there are few data available in relict permafrost regions although those data are important to understand the impacts of climate changes on permafrost especially in the boundary regions between permafrost and seasonally frozen ground regions. In this study, we present 11 years of meteorological and soil data in a relict permafrost site of the Mahan Mountain on the northeast of the Qinghai-Tibet Plateau. The meteorological data are comprised of air and ground surface temperature, relative humidity, wind speed and direction, shortwave and longwave downward and upward radiation, water vapor pressure, and precipitation on half-an-hour timescale. The active layer data include daily soil temperature and soil moisture at five different depths. The permafrost data consist of ground temperature at twenty different depths up to 28.4 m. The high-quality and long-term datasets are expected to serve as accurate forcing data in land surface models and evaluate remote-sensing products for a broader geoscientific community. The datasets are available from the National Tibetan Plateau/Third Pole Environment Data Center (https://doi.org/10.11888/Cryos.tpdc.271838, Wu and Xie, 2021).

scholarly journals Correlation of seasonal precipitation isotopic profile with the modern climatological data: a case study from the western Newfoundland region of Canada

2020 ◽  
pp. SP507-2020-100
Author(s):  
Brittany M. Marche ◽  
Harunur Rashid ◽  
Don-Roger Parkinson
Keyword(s):  
Liquid Water ◽  
Newfoundland And Labrador ◽  
Meteorological Data ◽  
Water Isotopes ◽  
Stable Water Isotopes ◽  
Atmospheric Circulation Patterns ◽  
Spatial Features ◽  
Circulation Patterns ◽  
Wet Climate

AbstractThe measurement of stable water isotopes (i.e. δ18O and δ2H) in precipitation is a powerful tool for detecting changes in climate patterns, assessing groundwater movements and studying the hydrological budget. In this study, daily precipitation was collected and δ18O and δ2H were analysed in Corner Brook, western Newfoundland, and Labrador, for 2015. The study provides the first background data of any kind related to liquid water isotopes in western Newfoundland. More than 130 samples were analysed using a state-of-the-art cavity ring-down spectrometer, the Picarro Liquid Water Isotope Analyzer L2130-i, with a minimal instrumental error. The data suggest seasonal variations in which the δ18O varies from −33.4 to −0.03‰ (±0.023‰) and δ2H ranges from −253.4 to 15.1‰ (±0.148‰). Our data are compared with modern meteorological data and publicly available δ18O and δ2H data from greater Atlantic Canada, which suggests that the atmospheric circulation patterns, spatial features and other climate factors are distinct in Corner Brook. Isotopes in meteorological precipitation data referenced and collected in this study reflect the cool, wet climate and air-mass fluctuations unique to the geographical region and thus, this baseline is fundamental to understanding the modern isotope hydrological/climatic studies for this region.

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