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  • 1
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    In:  [Talk] In: EGU General Assembly 2018, 08.-13.04.2018, Vienna, Austria .
    Publication Date: 2018-06-28
    Description: A large fraction of interannual variability of the East Asian Summer Monsoon (EASM) can be described by the first two modes of a Multivariate Empirical Orthogonal Functions (MV-EOF) analysis of horizontal wind vectors in the lower and upper troposphere over the East Asian region. The first mode resembles the Pacific-Japan pattern and represents about 20% of the EASM interannual variance. The positive phase of the PJ-pattern is associated with anomalous anticyclonic flow over the tropical western North Pacific in the lower troposphere, leading to enhanced rainfall over the climatological East Asian rain band. Focusing on June/July/August and on the first MV-EOF mode (PJ-mode here) we investigate the relation between tropical intraseasonal variability, namely the Madden-Julian Oscillation (MJO) and the EASM. The second MV-EOF mode had previously been found to be influenced mainly by the Indian Summer Monsoon and is not discussed in this presentation. First, it is found that the MJO modulates the intraseasonal variability of the PJ-pattern, in that early MJO phases, related to enhanced convective precipitation over the Indian Ocean, favour the positive phase of the PJ-mode and late MJO phases, related to enhanced convective precipitation over the Maritime Continent and the western tropical Pacific, favour the negative phase of the PJ-mode. Second, using a decomposition method introduced by Yoo, Feldstein and Lee (2011), we show that interannual variability of the MJO contributes about 11% to the interannual variability of the EASM. Thereby, interannual changes in the frequency of occurrence of the eight standard MJO phases are more important to the variability of the EASM than changes in the circulation patterns associated with the different MJO phases. Some discussion on the involved mechanisms will be given.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 2
    Publication Date: 2019-05-24
    Description: We investigate the daily variability of the East Asian summer monsoon (EASM) by projecting daily wind anomaly data onto the two major modes of an interannual multivariate Empirical Orthogonal Functions analysis. Mode 1, closely resembling the Pacific-Japan (PJ) pattern and referred to as PJ-mode, transits from positive to negative phase around mid-summer consistent with the Meiyu rains predominantly being an early summer phenomenon. Mode 2, which is influenced by the Indian summer monsoon (ISM) and referred to as ISM-mode, peaks in late July and early August and is associated with rainfall farther north over China. We then analyze the relation between the intraseasonal variation of the EASM and the Madden-Julian Oscillation (MJO) by analyzing circulation anomalies following MJO events. In the lower troposphere, the circulation anomalies associated with the MJO most strongly project on the PJ-mode. MJO phases 1-4 (5-8) favor the positive (negative) phase of the PJ-mode by favoring the anticyclonic (cyclonic) anomalies over the subtropical western North Pacific. In the upper troposphere, the circulation anomalies associated with the MJO project mainly on the ISM-mode.
    Type: Article , PeerReviewed
    Format: text
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  • 3
    Publication Date: 2019-05-28
    Description: The spatial pattern of the first mode of interannual variability associated with the East Asian summer monsoon (EASM), obtained from a multivariate Empirical Orthogonal Functions (MV-EOF) analysis, corresponds to the Pacific–Japan (PJ) pattern and is referred to as the PJ-mode. The present study investigates the interannual variation of the PJ-mode from the perspective of the intraseasonal timescale. In particular, the impact of the Madden–Julian oscillation (MJO) on the interannual variation of the PJ-mode is investigated. The results show that the MJO has a significant influence on the interannual variation of the PJ-mode mainly in the lower troposphere (850 hPa) and that the former accounts for approximately 11% of the amplitude of the latter. The major part of the contribution comes from a change in frequency of the different phases of the MJO, especially that of MJO phase 6. This suggests that intraseasonal variation of the convection anomalies over the tropical eastern Indian and western Pacific Oceans plays an important role in the interannual variation of the PJ-mode. In addition, MJO phase 7 also contributes to the interannual variability of the PJ-mode, in this case induced by both the change in frequency and the change in circulation anomalies associated with MJO phase 7.
    Type: Article , PeerReviewed
    Format: text
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  • 4
    Publication Date: 2016-10-16
    Description: In order to selectively remove iron from copper laden solution after leaching but prior to electrowinning, equilibrium, kinetic, and thermodynamic studies have been conducted on an a chelating resin of Rexp-501 at pH 1.0 and at various temperatures. Both Langmuir and Freundlich models were investigated, with the Langmuir model proving to be more suitable for fitting iron removal performance, with little influence from copper concentration. Compared with the pseudo first order kinetic model, the pseudo second order kinetic model fitted the dynamic adsorption process better, indicating a chemisorption mechanism. Fourier transform infrared spectroscopy (FT-IR) results indicated that C=O from carbonyl group played a key role in combining with iron and can be regenerated and reused. However, the C=O of the acylamino group combining with iron was not able to be released after oxalic acid was applied.
    Electronic ISSN: 2075-163X
    Topics: Geosciences
    Published by MDPI Publishing
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  • 5
    Publication Date: 2016-11-19
    Description: Nitrate (NO 3 - ) pollution is a serious problem worldwide, particularly in countries with intensive agricultural and population activities. Previous studies have used δ 15 N-NO 3 - and δ 18 O-NO 3 - to determine the NO 3 - sources in rivers. However, this approach is subject to substantial uncertainties and limitations because of the numerous NO 3 - sources, the wide isotopic ranges, and the existing isotopic fractionations. In this study, we outline a combined procedure for improving the determination of NO 3 - sources in a paddy agriculture–urban gradient watershed in eastern China. First, the main sources of NO 3 - in the Qinhuai River were examined by the dual isotope bi-plot approach, in which we narrowed the isotope ranges using site-specific isotopic results. Next, the bacterial groups and chemical properties of the river water were analyzed to verify these sources. Finally, we introduced a Bayesian model to apportion the spatio-temporal variations of the NO 3 - sources. Denitrification was first incorporated into the Bayesian model because denitrification plays an important role in the nitrogen pathway. The results showed that fertilizer contributed large amounts of NO 3 - to the surface water in traditional agricultural regions, whereas manure effluents were the dominant NO 3 - source in intensified agricultural regions, especially during the wet seasons. Sewage effluents were important in all three land uses and exhibited great differences between the dry season and the wet season. This combined analysis quantitatively delineates the proportion of NO 3 - sources from paddy agriculture to urban river water for both dry and wet seasons and incorporates isotopic fractionation and uncertainties in the source compositions.
    Print ISSN: 0148-0227
    Topics: Biology , Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 6
    Publication Date: 2016-12-03
    Description: Analytical Chemistry DOI: 10.1021/acs.analchem.6b03501
    Print ISSN: 0003-2700
    Electronic ISSN: 1520-6882
    Topics: Chemistry and Pharmacology
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  • 7
    Publication Date: 2018-05-29
    Description: Water, Vol. 10, Pages 698: A Dynamic Study of a Karst Spring Based on Wavelet Analysis and the Mann-Kendall Trend Test Water doi: 10.3390/w10060698 Authors: Liting Xing Linxian Huang Guangyao Chi Lizhi Yang Changsuo Li Xinyu Hou Over the last 40 years, declining spring water flow rates have become a typical feature of karst springs in Northern China. Wavelet analysis, the Mann-Kendall trend test and the mutation test were used to analyze dynamic monitoring data of groundwater levels and atmospheric precipitation in the Jinan karst spring area, from 1956 to 2013, to study hydrological responses to atmospheric precipitation over one-year periods. Results from this analysis show that: (1) Atmospheric precipitation and the spring water level displayed multi-scale change characteristics, having two very similar cycles of change of 16 and 12 years. This finding shows that atmospheric precipitation generates a direct impact on the level of spring water. (2) From 1956 to 2013, the groundwater level in the Jinan spring area had a significant downward trend (0.65 m/10a). Precipitation recorded an increasing trend (12.65 mm/10a), however this was not significant. The weight of the influencing factors of the spring dynamic therefore changed due to the influence of human factors. (3) A mutation of atmospheric precipitation occurred in 1999, after which annual precipitation increased. Results for the mutation of the groundwater level showed an initial change in 1967. After this change the water level continued to decrease before rapidly increasing after 2004. The future trend of the spring water level should be maintained with consistent precipitation (having an upward trend), indicating that atmospheric precipitation is not the only factor affecting the dynamics of the spring. (4) Different periods were identified on the multiple regression model. The main influencing factors on groundwater level over the past 58 years were identified as a transition from precipitation to artificial mining. These results also validate the suitability and reliability of using wavelet analysis and the Mann-Kendall test method to study groundwater dynamics; these results provide a reference for the future protection of the Jinan City spring.
    Electronic ISSN: 2073-4441
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI Publishing
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  • 8
    Publication Date: 2017-11-30
    Description: Journal of the American Chemical Society DOI: 10.1021/jacs.7b11283
    Print ISSN: 0002-7863
    Electronic ISSN: 1520-5126
    Topics: Chemistry and Pharmacology
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  • 9
    Publication Date: 2017-06-08
    Description: Journal of Medicinal Chemistry DOI: 10.1021/acs.jmedchem.7b00468
    Topics: Chemistry and Pharmacology
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  • 10
    Publication Date: 2017-04-04
    Description: CdO ceramics with randomly distributed micropores were synthesized by the conventional solid-state reaction method via adding polymethyl methacrylate (PMMA) as the void forming agent. The introduction of microsized pores can significantly affect both electrical and thermal transport properties of the CdO matrix, and possible underlying mechanisms are discussed. Due to the dramatically reduced thermal conductivity, a highest ZT value of ~0.51 has been achieved in the porous CdO at about 1000 K, increased by about 52% as compared to that of the dense sample without PMMA addition. This work demonstrates that introducing microsized pores is a very simple, low-cost, and efficient strategy to improve the high-temperature thermoelectric performance of CdO ceramics.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
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