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Xie H, Zhou T, Fu Q, Huang J, Huang Z, Bi J, Shi J, Zhang B, Ge J. Automated detection of cloud and aerosol features with SACOL micro-pulse lidar in northwest China. OPTICS EXPRESS 2017; 25:30732-30753. [PMID: 29221100 DOI: 10.1364/oe.25.030732] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 10/31/2017] [Indexed: 06/07/2023]
Abstract
The detection of cloud and aerosols using a modified retrieval algorithm solely for a ground-based micropulse lidar (MPL) is presented, based on one-year data at the Semi-Arid Climate Observatory and Laboratory (SACOL) site (35.57°N, 104.08°E, 1965.8 m), northwest of China, from March 2011 to February 2012. The work not only identifies atmosphere particle layers by means of the range-dependent thresholds based on elastic scattering ratio and depolarization ratio, but also discriminates the detected layers by combining empirical thresholds of the atmosphere's thermodynamics states and scattering properties and continuous wavelet transform (CWT) analyses. Two cases were first presented in detail that demonstrated that the modified algorithm can capture atmosphere layers well. The cloud macro-physical properties including cloud base height (CBH), cloud geometrical thickness (CGT), and cloud fraction (CF) were then analyzed in terms of their monthly and seasonal variations. It is shown that the maximum/minimum CBHs were found in summer (4.66 ± 1.95km)/autumn (3.34 ± 1.84km). The CGT in winter (1.05 ± 0.43km) is slightly greater than in summer (0.99 ± 0.44km). CF varies significantly throughout year, with the maximum value in autumn (0.68), and a minimum (0.58) in winter, which is dominated by single-layered clouds (81%). The vertical distribution of CF shows a bimodal distribution, with a lower peak between 1 and 4km and a higher one between 6and 9km. The seasonal and vertical variations in CF are important for the local radiative energy budget.
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Li Z, Yang S, He B, Hu C. Intensified Springtime Deep Convection over the South China Sea and the Philippine Sea Dries Southern China. Sci Rep 2016; 6:30470. [PMID: 27461985 PMCID: PMC4962042 DOI: 10.1038/srep30470] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 06/29/2016] [Indexed: 11/22/2022] Open
Abstract
Springtime rainfall, accounting for 25–40% of the annual rainfall in southern China, exerts great agricultural and socioeconomic impacts on the region. In the recent decades, southern China has experienced a significant declining trend of precipitation in boreal spring. Meanwhile, precipitation has increased over the South China Sea and the Philippine Sea (SCS-PhS). This paper presents observational and modeling evidences suggesting that the intensified latent heating released by the convection over SCS-PhS leads to suppressed springtime rainfall over southern China. Moisture budget analysis indicates that the drying trend over southern China is due mainly to weakened convergence of moisture flux, which is controlled by a heat-induced anomalous overturning circulation reinforced by the convection over SCS-PhS. Further idealized simulations support the feature that the heat-induced overturning circulation and its corresponding anomalous cyclone can be well established in several days under the spring mean flow condition. Thus, this rapid dynamic process is associated with both the intraseasonal-to-interannual variations and the long-term change of the springtime rainfall over southern China.
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Affiliation(s)
- Zhenning Li
- School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Song Yang
- School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China.,Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou, Guangdong, China.,Institute of Earth Climate and Environment System, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Bian He
- State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Chundi Hu
- Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou, Guangdong, China.,School of Atmospheric Sciences, Nanjing University, Nanjing, Jiangsu, China
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Zhao J, Wang B, Yang L, Cheng C, Song Y. A novel apparatus for in situ measurement of thermal conductivity of hydrate-bearing sediments. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:085110. [PMID: 26329236 DOI: 10.1063/1.4928106] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
An experimental apparatus was developed to synthesize natural gas hydrates and measure the thermal conductivity of hydrate-bearing sediments in situ. The apparatus works over a temperature range varying from -20 °C to 50 °C and up to a maximum pressure of 20 MPa. This apparatus is mainly composed of a thermal conductivity test system and a reaction cell, into which a lab-fabricated thermistor probe is inserted. This thermistor has excellent temperature sensitivity and can work at high pressures. The basic principles of this apparatus are discussed, and a series of experiments were performed to verify that the apparatus can be practically applied in chemical engineering. The thermistor-based measuring method was applied successfully in a high-pressure environment both with and without porous media.
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Affiliation(s)
- Jiafei Zhao
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, People's Republic of China
| | - Bin Wang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, People's Republic of China
| | - Lei Yang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, People's Republic of China
| | - Chuanxiao Cheng
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, People's Republic of China
| | - Yongchen Song
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, People's Republic of China
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Cheng WL, Lai LW, Den W, Wu MT, Hsueh CA, Lin PL, Pai CL, Yan YL. The relationship between typhoons' peripheral circulation and ground-level ozone concentrations in central Taiwan. ENVIRONMENTAL MONITORING AND ASSESSMENT 2014; 186:791-804. [PMID: 24105123 DOI: 10.1007/s10661-013-3417-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 09/05/2013] [Indexed: 06/02/2023]
Abstract
Surface data of meteorological parameters (wind speed, wind direction, and mixing height) and air pollutant concentrations (O3, NO, and NO2) were collected for a 92-day period associated with typhoon formation in 2005. The influence of typhoons on O3 concentration were defined by azimuth and distance from Taiwan, and Types A, B, and C correspond to typhoons less than 1,500 km from Taiwan and located between azimuths 45° and 135°, 135° and 225°, and 225° and 45°, respectively. Type D corresponds to typhoons more than 1,500 km from Taiwan. Titration reactions were conducted at three temporal phases: 2000-0700, 0800-1100, and 1200-1400 LST (Local Standard Time). The air pollution model (TAPM) was used to simulate wind fields and trajectories of air masses. It was determined that typhoon position affected O3 concentration, temporal and spatial patterns of O3 titration and vertical meteorological characteristics, which were not all at the statistically significant level.
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Affiliation(s)
- Wan-Li Cheng
- Taiwan Development Institute, Taichung, 407, Taiwan, Republic of China
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Upper mantle viscosity and dynamic subsidence of curved continental margins. Nat Commun 2013; 4:2036. [PMID: 23774453 DOI: 10.1038/ncomms3036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 05/19/2013] [Indexed: 11/08/2022] Open
Abstract
Continental rifting does not always follow a straight line. Nevertheless, little attention has been given to the influence of rifting curvature in the evolution of extended margins. Here, using a three-dimensional model to simulate mantle dynamics, we demonstrate that the curvature of rifting along a margin also controls post-rift basin subsidence. Our results indicate that a concave-oceanward margin subsides faster than a convex margin does during the post-rift phase. This dynamic subsidence of curved margins is a result of lateral thermal conduction and mantle convection. Furthermore, the differential subsidence is strongly dependent on the viscosity structure. As a natural example, we analyse the post-rift stratigraphic evolution of the Santos Basin, southeastern Brazil. The differential dynamic subsidence of this margin is only possible if the viscosity of the upper mantle is >2-3 × 10(19) Pa s.
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Wang D, Li D, Zhang H, Fan S, Zhao H. Laboratory measurement of longitudinal wave velocity of artificial gas hydrate under different temperatures and pressures. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s11433-008-0166-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Zhou Y, Kratz DP, Wilber AC, Gupta SK, Cess RD. An improved algorithm for retrieving surface downwelling longwave radiation from satellite measurements. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jd008159] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Minnis P, Huang J, Lin B, Yi Y, Arduini RF, Fan TF, Ayers JK, Mace GG. Ice cloud properties in ice-over-water cloud systems using Tropical Rainfall Measuring Mission (TRMM) visible and infrared scanner and TRMM Microwave Imager data. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jd007626] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Minnis P, Yi Y, Huang J, Ayers K. Relationships between radiosonde and RUC-2 meteorological conditions and cloud occurrence determined from ARM data. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2005jd006005] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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