In this paper, the authors define the spring monsoon in South China, and study the climatology and the interannual variation through analysis of the precipitation and the related atmospheric circulation, as revealed b...In this paper, the authors define the spring monsoon in South China, and study the climatology and the interannual variation through analysis of the precipitation and the related atmospheric circulation, as revealed by the NCEP/ NCAR reanalysis data. The results indicate that the spring monsoon season in South China occurs climatologically in April and May, which is supported by both seasonal and interannual variation of the atmospheric circulation and precipitation. The related atmospheric circulation is different from that during the East Asian summer or winter monsoon season. The interannual variation of the spring monsoon rainfall in South China relates primarily to the anomalous circulation over the North Pacific, which is linked with the westerly jet over North Asia and with the polar vortex. It is also connected with sea surface temperature anomalies in the Pacific. Changes in the Asian tropical atmospheric circulation has little influence on the spring monsoon in South China according to this research.展开更多
Climatic changes in the onset of spring in northern China associated with changes in the annual cycle and with a recent warming trend were quantified using a recently developed adaptive data analysis tool, the Ensembl...Climatic changes in the onset of spring in northern China associated with changes in the annual cycle and with a recent warming trend were quantified using a recently developed adaptive data analysis tool, the Ensemble Empirical Mode Decomposition. The study was based on a homogenized daily surface air temperature （SAT） dataset for the period 1955–2003. The annual cycle here is referred to as a refined modulated annual cycle （MAC）. The results show that spring at Beijing has arrived significantly earlier by about 2.98 d （10 yr）-1, of which about 1.85 d （10 yr）-1 is due to changes in the annual cycle and 1.13 d （10 yr）-1 due to the long-term warming trend. Variations in the MAC component explain about 92.5% of the total variance in the Beijing daily SAT series and could cause as much as a 20-day shift in the onset of spring from one year to another. The onset of spring has been advancing all over northern China, but more significant in the east than in the west part of the region. These differences are somehow unexplainable by the zonal pattern of the warming trend over the whole region, but can be explained by opposite changes in the spring phase of the MAC, i.e. advancing in the east while delaying in the west. In the east of northern China, the change in the spring phase of MAC explains 40%–60% of the spring onset trend and is attributable to a weakening Asian winter monsoon. The average sea level pressure in Siberia （55°–80°N, 50°–110°E）, an index of the strength of the winter monsoon, could serve as a potential short-term predictor for the onset of spring in the east of northern China.展开更多
A preliminary study was conducted to analyze the water quality of spring waters in rural watershed of Western Nepal. 155 spring water samples were collected from Jhimruk, Rangun, Bogtan-Lagam Karnali, Thuligad and Mid...A preliminary study was conducted to analyze the water quality of spring waters in rural watershed of Western Nepal. 155 spring water samples were collected from Jhimruk, Rangun, Bogtan-Lagam Karnali, Thuligad and Middle Karnali watershed. Collection and analysis occurred twice, once in pre-monsoon 2018 and post-monsoon 2018. Various physical and chemical parameters were analyzed by using standard water quality measurements and compared with the Nepal Drinking Water Quality Standard and the World Health Organization Standard Guideline. The results indicate that the turbidity was high during pre-monsoon season. The highest turbidity of 63.8 NTU was observed in the Bogtan-Lagam Karnali watershed. Two spring sources—one in Bogtan-Lagam Karnali and one in Middle Karnali exceeded the health standard for nitrate-N. The phosphate levels were high during the pre-monsoon season in Jhimruk and Rangun watershed in all the studied sites. Dissolved oxygen levels were relatively high during post-monsoon season. Results of the water quality index in all the studied sites revealed that the water quality ranges from being poor to good conditions in the spring sources. The results from this study suggested that the water bodies are relatively good and can be used for domestic purposes after suitable treatment.展开更多
基金Acknowledgments. This research was jointly supported by the Chinese Academy of Sciences Key Project under Grant No. KZCX2-203, the National Natural Science Foundation of China under Grant No. 40125014, and the Na-tional Key Program under Grant No. G19980
文摘In this paper, the authors define the spring monsoon in South China, and study the climatology and the interannual variation through analysis of the precipitation and the related atmospheric circulation, as revealed by the NCEP/ NCAR reanalysis data. The results indicate that the spring monsoon season in South China occurs climatologically in April and May, which is supported by both seasonal and interannual variation of the atmospheric circulation and precipitation. The related atmospheric circulation is different from that during the East Asian summer or winter monsoon season. The interannual variation of the spring monsoon rainfall in South China relates primarily to the anomalous circulation over the North Pacific, which is linked with the westerly jet over North Asia and with the polar vortex. It is also connected with sea surface temperature anomalies in the Pacific. Changes in the Asian tropical atmospheric circulation has little influence on the spring monsoon in South China according to this research.
基金sponsored by the National Basic Research Program of China(Grant Nos. 2011CB952000, 2006CB400504)the Na-tional Natural Science Foundation of China (Grant No.41005039)+1 种基金Wu was sponsored by the National Science Foundation of USA (ATM-0917743)Yan was sponsored by the National Basic Research Program of China(Grant No. 2009CB421401)
文摘Climatic changes in the onset of spring in northern China associated with changes in the annual cycle and with a recent warming trend were quantified using a recently developed adaptive data analysis tool, the Ensemble Empirical Mode Decomposition. The study was based on a homogenized daily surface air temperature （SAT） dataset for the period 1955–2003. The annual cycle here is referred to as a refined modulated annual cycle （MAC）. The results show that spring at Beijing has arrived significantly earlier by about 2.98 d （10 yr）-1, of which about 1.85 d （10 yr）-1 is due to changes in the annual cycle and 1.13 d （10 yr）-1 due to the long-term warming trend. Variations in the MAC component explain about 92.5% of the total variance in the Beijing daily SAT series and could cause as much as a 20-day shift in the onset of spring from one year to another. The onset of spring has been advancing all over northern China, but more significant in the east than in the west part of the region. These differences are somehow unexplainable by the zonal pattern of the warming trend over the whole region, but can be explained by opposite changes in the spring phase of the MAC, i.e. advancing in the east while delaying in the west. In the east of northern China, the change in the spring phase of MAC explains 40%–60% of the spring onset trend and is attributable to a weakening Asian winter monsoon. The average sea level pressure in Siberia （55°–80°N, 50°–110°E）, an index of the strength of the winter monsoon, could serve as a potential short-term predictor for the onset of spring in the east of northern China.
文摘A preliminary study was conducted to analyze the water quality of spring waters in rural watershed of Western Nepal. 155 spring water samples were collected from Jhimruk, Rangun, Bogtan-Lagam Karnali, Thuligad and Middle Karnali watershed. Collection and analysis occurred twice, once in pre-monsoon 2018 and post-monsoon 2018. Various physical and chemical parameters were analyzed by using standard water quality measurements and compared with the Nepal Drinking Water Quality Standard and the World Health Organization Standard Guideline. The results indicate that the turbidity was high during pre-monsoon season. The highest turbidity of 63.8 NTU was observed in the Bogtan-Lagam Karnali watershed. Two spring sources—one in Bogtan-Lagam Karnali and one in Middle Karnali exceeded the health standard for nitrate-N. The phosphate levels were high during the pre-monsoon season in Jhimruk and Rangun watershed in all the studied sites. Dissolved oxygen levels were relatively high during post-monsoon season. Results of the water quality index in all the studied sites revealed that the water quality ranges from being poor to good conditions in the spring sources. The results from this study suggested that the water bodies are relatively good and can be used for domestic purposes after suitable treatment.
