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Event-based extreme precipitation (EEP), defined as an extreme precipitation event (no less than 1 mm for continuous days) having at least one daily precipitation exceeding the 90th percentile, are categorized into three types according to the time distribution pattern (TDP) of extreme precipitation: daily intense precipitation appearing only at the first half of event (TDP1), at both the first and second halves (TDP2), and only at the second half of event (TDP3). This study focuses on the TDP1 and TDP2 types, which occur much more frequently in the central-eastern China and investigates associated distinguishing large-scale teleconnection patterns. The TDP1 events dominantly occur in mid-to-late spring, which are associated with the Silk Road pattern (SRP) wave train manifested from western Europe to northwest Pacific along the subtropical westerly jet. The tripolar sea surface temperature (SST) anomalous pattern over the North Atlantic Ocean, i.e., low SST anomalies in the Azores Islands, two high SST anomalies over the Greenland and subtropical North Atlantic are mainly attributed to force the SRP wave. Meanwhile, the enhanced northwestward moisture transport from the South China converges with the southeastward moisture transport related to the SRP from the North China, resulting in the TDP1 extreme precipitation events over the central-eastern China. The TDP2 events are closely conjunction with the Meiyu precipitation in the Yangtze-Huai River basin in summer. During the TDP2 events, the East Asia/Pacific (EAP) teleconnection is exhibited along the East Asia coasts, which is triggered by the anomalous convection in the western North Pacific. An anomalous anticyclone related to the EAP teleconnection contributes to the westward stretch of the western Pacific subtropical high, providing significant enhanced moisture transportation toward the Yangtze-Huai River basin. Correspondingly, the meridional gradient of the equivalent potential temperature \(\theta_{e}\) is intensified and favored of forming Meiyu front precipitation. This study highlights the definition of EEP event emphasizing the TDP of extreme precipitation and distinguished features of occurring seasons and large-scale circulations associated with the two dominant types of EEP events.
Wei Shang; Shuangshuang Li; Xuejuan Ren; Keqin Duan. Event-based extreme precipitation in Central-Eastern China: large-scale anomalies and teleconnections. Climate Dynamics 2020, 54, 2347 -2360.
AMA StyleWei Shang, Shuangshuang Li, Xuejuan Ren, Keqin Duan. Event-based extreme precipitation in Central-Eastern China: large-scale anomalies and teleconnections. Climate Dynamics. 2020; 54 (3-4):2347-2360.
Chicago/Turabian StyleWei Shang; Shuangshuang Li; Xuejuan Ren; Keqin Duan. 2020. "Event-based extreme precipitation in Central-Eastern China: large-scale anomalies and teleconnections." Climate Dynamics 54, no. 3-4: 2347-2360.
In recent decades, the monitoring of vegetation dynamics has become crucial because of its important role in terrestrial ecosystems. In this study, a satellite-derived normalized difference vegetation index (NDVI) was combined with climate factors to explore the spatiotemporal patterns of vegetation change during the growing season, as well as their driving forces in China from 2001 to 2012. Our results showed that the growing season NDVI increased continuously during 2001–2012, with a linear trend of 1.4%/10 years (p < 0.01). The NDVI in north China mainly exhibited an increasing spatial trend, but this trend was generally decreasing in south China. The vegetation dynamics were mainly at a moderate intensity level in both the increasing and decreasing areas. The significantly increasing trend in the NDVI for arid and semi-arid areas of northwest China was attributed mainly to an increasing trend in the NDVI during the spring, whereas that for the north and northeast of China was due to an increasing trend in the NDVI during the summer and autumn. Different vegetation types exhibited great variation in their trends, where the grass-forb community had the highest linear trend of 2%/10 years (p < 0.05), followed by meadow, and needle-leaf forest with the lowest increasing trend, i.e., a linear trend of 0.3%/10 years. Our results also suggested that the cumulative precipitation during the growing season had a dominant effect on the vegetation dynamics compared with temperature for all six vegetation types. In addition, the response of different vegetation types to climate variability exhibited considerable differences. In terms of anthropological activity, our statistical analyses showed that there was a strong correlation between the cumulative afforestation area and NDVI during the study period, especially in a pilot region for ecological restoration, thereby suggesting the important role of ecological restoration programs in ecological recovery throughout China in the last decade.
Xianfeng Liu; Xiufang Zhu; Shuangshuang Li; Yanxu Liu; Yaozhong Pan. Changes in Growing Season Vegetation and Their Associated Driving Forces in China during 2001–2012. Remote Sensing 2015, 7, 15517 -15535.
AMA StyleXianfeng Liu, Xiufang Zhu, Shuangshuang Li, Yanxu Liu, Yaozhong Pan. Changes in Growing Season Vegetation and Their Associated Driving Forces in China during 2001–2012. Remote Sensing. 2015; 7 (11):15517-15535.
Chicago/Turabian StyleXianfeng Liu; Xiufang Zhu; Shuangshuang Li; Yanxu Liu; Yaozhong Pan. 2015. "Changes in Growing Season Vegetation and Their Associated Driving Forces in China during 2001–2012." Remote Sensing 7, no. 11: 15517-15535.
In recent decades, climate change has affected vegetation growth in terrestrial ecosystems. We investigated spatial and temporal patterns of vegetation cover on the Loess Plateau’s Shaanxi-Gansu-Ningxia region in central China using MODIS-NDVI data for 2000–2014. We examined the roles of regional climate change and human activities in vegetation restoration, particularly from 1999 when conversion of sloping farmland to forestland or grassland began under the national Grain-for-Green program. Our results indicated a general upward trend in average NDVI values in the study area. The region’s annual growth rate greatly exceeded those of the Three-North Shelter Forest, the upper reaches of the Yellow River, the Qinling–Daba Mountains, and the Three-River Headwater region. The green vegetation zone has been annually extending from the southeast toward the northwest, with about 97.4% of the region evidencing an upward trend in vegetation cover. The NDVI trend and fluctuation characteristics indicate the occurrence of vegetation restoration in the study region, with gradual vegetation stabilization associated with 15 years of ecological engineering projects. Under favorable climatic conditions, increasing local vegetation cover is primarily attributable to ecosystem reconstruction projects. However, our findings indicate a growing risk of vegetation degradation in the northern part of Shaanxi Province as a result of energy production facilities and chemical industry infrastructure, and increasing exploitation of mineral resources.
Shuangshuang Li; Saini Yang; Xianfeng Liu; Yanxu Liu; Mimi Shi. NDVI-Based Analysis on the Influence of Climate Change and Human Activities on Vegetation Restoration in the Shaanxi-Gansu-Ningxia Region, Central China. Remote Sensing 2015, 7, 11163 -11182.
AMA StyleShuangshuang Li, Saini Yang, Xianfeng Liu, Yanxu Liu, Mimi Shi. NDVI-Based Analysis on the Influence of Climate Change and Human Activities on Vegetation Restoration in the Shaanxi-Gansu-Ningxia Region, Central China. Remote Sensing. 2015; 7 (9):11163-11182.
Chicago/Turabian StyleShuangshuang Li; Saini Yang; Xianfeng Liu; Yanxu Liu; Mimi Shi. 2015. "NDVI-Based Analysis on the Influence of Climate Change and Human Activities on Vegetation Restoration in the Shaanxi-Gansu-Ningxia Region, Central China." Remote Sensing 7, no. 9: 11163-11182.