Attributing vegetation changes provide fundamental information for ecosystem management,especially in mountainous areas which has vulnerable ecosystems. Based on the Normalized Difference Vegetation Index(NDVI) data, ...Attributing vegetation changes provide fundamental information for ecosystem management,especially in mountainous areas which has vulnerable ecosystems. Based on the Normalized Difference Vegetation Index(NDVI) data, the spatial-temporal change of vegetation was detected in Taihang Mountain(THM) from 2000 to 2014. The topographical factors were introduced to interpret the response of vegetation variation to climate change and human activities. Results showed that the avegaged NDVI during growing season showed a single-peak curve distribution, with the largest value(0.628) among 1600-1800 m. A significant greening trend was detected in THM, with the largest increasing rate(0.0078 yr^(-1)) among the elevation of1600-1800 m and slope gradient between 3~5°. The partial correlation and multiple correlation analyses indicated that vegetation variation in more than81.8% pixels of the THM was mainly impacted by human activities. In the low elevation zones less than1000 m, increasing precipitation is the principle factor promoting vegetation restoration, whereas in the high elevation zones of THM, temperature is the restricted factors impacting vegetation variation.Considering the dramatic climate change in the future,further studies should be conducted to explore inherent mechanism of vegetation growth to dynamic environment changes.展开更多
An investigation was conducted to study problems of determining a reasonable percentage for ecological water-use in the Haihe River Basin of China. Three key aspects for the ecological water requirement （EWR） were a...An investigation was conducted to study problems of determining a reasonable percentage for ecological water-use in the Haihe River Basin of China. Three key aspects for the ecological water requirement （EWR） were analyzed, involving i） the EWR for river system, ii） the EWR for wetlands and lakes, and iii） the EWR for discharge into the sea to maintain the estuary ecological balance of the Haihe River. The Montana method and related water level-flow relationships, and the statistic approach based on hydrological records were applied to estimate different components of EWR. The results showed that the total ecological water demand in the region, was about 3.47-14.56 billion m^3. Considering flow regime change and uncertainty, the ecological water demand could be estimated by the hydrological frequency approach. Preliminary analysis showed that for different annual runoff under the frequencies of 20%, 50%, 75% and 95%, the ecological water demand approached 12%-50%, 18%-74%, 24%-103%, 35%-148% and 16%-66%, respectively. By further analysis to balance ecological water-use and socioeconomic water-use, the rational percentage of ecological water-use was estimated as 35%-74%, that provides useful information to judge whether the allocation of water resources is reasonable, and was proved to be satisfactory by comparing with the practical condition.展开更多
利用海洋-大气-海浪耦合模式COAWST进行了两组以东海区域为中心的72 h模拟试验。通过对比考虑动态海浪过程与未考虑该过程的试验结果,分析动态海浪过程对短期天气模拟的影响。结果表明,考虑动态海浪过程后将增强海表感热、潜热通量的模...利用海洋-大气-海浪耦合模式COAWST进行了两组以东海区域为中心的72 h模拟试验。通过对比考虑动态海浪过程与未考虑该过程的试验结果,分析动态海浪过程对短期天气模拟的影响。结果表明,考虑动态海浪过程后将增强海表感热、潜热通量的模拟,造成海表大气增暖增湿。这一暖湿差异将促进大气垂向运动的发展,造成海平面低压发展,并进一步影响大气流场的变化,增强局地升温效果,有利于形成正反馈。该暖湿差异在南海西北部与菲律宾海域最为明显,且随高度上升逐渐减弱,至500 h Pa高度时差异基本消失。展开更多
基金supported by the National Basic Research Program of China(973 Program,No.2015CB452701)National Natural Science Foundation of China(No.41571019)
文摘Attributing vegetation changes provide fundamental information for ecosystem management,especially in mountainous areas which has vulnerable ecosystems. Based on the Normalized Difference Vegetation Index(NDVI) data, the spatial-temporal change of vegetation was detected in Taihang Mountain(THM) from 2000 to 2014. The topographical factors were introduced to interpret the response of vegetation variation to climate change and human activities. Results showed that the avegaged NDVI during growing season showed a single-peak curve distribution, with the largest value(0.628) among 1600-1800 m. A significant greening trend was detected in THM, with the largest increasing rate(0.0078 yr^(-1)) among the elevation of1600-1800 m and slope gradient between 3~5°. The partial correlation and multiple correlation analyses indicated that vegetation variation in more than81.8% pixels of the THM was mainly impacted by human activities. In the low elevation zones less than1000 m, increasing precipitation is the principle factor promoting vegetation restoration, whereas in the high elevation zones of THM, temperature is the restricted factors impacting vegetation variation.Considering the dramatic climate change in the future,further studies should be conducted to explore inherent mechanism of vegetation growth to dynamic environment changes.
基金Project supported by the Natural Science Foundation of China (No. 50279049)the Knowledge Innovation Key Project of the Chinese Academy of Sciences (Nos. CX10G-E01-08 and KZCX2-SW-317)the National Challenging Program of Science and Technology of China (No. 2004BA610A-01).
文摘An investigation was conducted to study problems of determining a reasonable percentage for ecological water-use in the Haihe River Basin of China. Three key aspects for the ecological water requirement （EWR） were analyzed, involving i） the EWR for river system, ii） the EWR for wetlands and lakes, and iii） the EWR for discharge into the sea to maintain the estuary ecological balance of the Haihe River. The Montana method and related water level-flow relationships, and the statistic approach based on hydrological records were applied to estimate different components of EWR. The results showed that the total ecological water demand in the region, was about 3.47-14.56 billion m^3. Considering flow regime change and uncertainty, the ecological water demand could be estimated by the hydrological frequency approach. Preliminary analysis showed that for different annual runoff under the frequencies of 20%, 50%, 75% and 95%, the ecological water demand approached 12%-50%, 18%-74%, 24%-103%, 35%-148% and 16%-66%, respectively. By further analysis to balance ecological water-use and socioeconomic water-use, the rational percentage of ecological water-use was estimated as 35%-74%, that provides useful information to judge whether the allocation of water resources is reasonable, and was proved to be satisfactory by comparing with the practical condition.
文摘利用海洋-大气-海浪耦合模式COAWST进行了两组以东海区域为中心的72 h模拟试验。通过对比考虑动态海浪过程与未考虑该过程的试验结果,分析动态海浪过程对短期天气模拟的影响。结果表明,考虑动态海浪过程后将增强海表感热、潜热通量的模拟,造成海表大气增暖增湿。这一暖湿差异将促进大气垂向运动的发展,造成海平面低压发展,并进一步影响大气流场的变化,增强局地升温效果,有利于形成正反馈。该暖湿差异在南海西北部与菲律宾海域最为明显,且随高度上升逐渐减弱,至500 h Pa高度时差异基本消失。
