A singular value decomposition （SVD） analysis is carried out to reveal the relationship between the interannual variation of track and intensity of the western North Pacific tropical cyclones （WNPTCs） in the tropi...A singular value decomposition （SVD） analysis is carried out to reveal the relationship between the interannual variation of track and intensity of the western North Pacific tropical cyclones （WNPTCs） in the tropical cyclone （TC） active season （July–November） and the global net air-sea heat flux （Q net ） in the preceding season （April–June）. For this purpose, a tropical cyclone track and intensity function （TIF） is defined by a combination of accumulated cyclone energy （ACE） index and a cyclone track density function. The SVD analysis reveals that the first mode is responsible for the positive correlation between the upward heat flux in the tropical central Pacific and the increased activity of western North Pacific （WNP） TIF, the second mode for the positive correlation between the upward heat flux in the North Indian Ocean and the northeastward track shift of WNPTCs and the third mode for the negative correlation between the upward heat flux in mid-latitude central Pacific and the northwest displacement of the WNP TC-active center. This suggests that Q net anomalies in some key regions have a substantial remote impact on the WNP TC activity.展开更多
温室效应已成为重要的全球气候问题,而内陆水体是温室气体(CO_(2)和CH_(4))的重要排放源,更有研究发现筑坝蓄水可能引起河流水体CO_(2)和CH_(4)排放的增多。为积极响应国家“双碳”目标,使用水库温室气体净排放通量评估模型G-res Tool,...温室效应已成为重要的全球气候问题,而内陆水体是温室气体(CO_(2)和CH_(4))的重要排放源,更有研究发现筑坝蓄水可能引起河流水体CO_(2)和CH_(4)排放的增多。为积极响应国家“双碳”目标,使用水库温室气体净排放通量评估模型G-res Tool,利用流域基本信息及水库特征数据,对澜沧江干流已建成的10座梯级水库温室气体(CO_(2)和CH_(4))进行模拟计算,10座水库蓄水后温室气体(CO_(2)和CH_(4))年排放通量平均值为162.81 g CO_(2)e/(m^(2)·a),远低于全球水库平均水平,均表现为温室气体的“源”,从上游至下游整体呈增加趋势,且排放以CO_(2)为主,全年CO_(2)排放通量为CH_(4)的36倍。考虑了水库蓄水前的温室气体排放及其他非相关人类活动的影响后,得到澜沧江水库温室气体(CO_(2)和CH_(4))年净排放通量平均值为225.70 g CO_(2)e/(m^(2)·a),表明筑坝增加了库区水体温室气体排放,但和火力发电相比,仍属于相对清洁能源。展开更多
贵州省是我国喀斯特生态系统的典型分布区,生态敏感且脆弱,同时其也曾是我国的连片特困区,经济发展愿望迫切。对区域环境-经济发展状况及相互作用关系进行研究具有重要意义。研究从植被净生态系统生产力、土壤碳储量、岩溶碳通量三方面...贵州省是我国喀斯特生态系统的典型分布区,生态敏感且脆弱,同时其也曾是我国的连片特困区,经济发展愿望迫切。对区域环境-经济发展状况及相互作用关系进行研究具有重要意义。研究从植被净生态系统生产力、土壤碳储量、岩溶碳通量三方面计算了贵州省陆地生态系统碳吸收,以能源燃烧排放的CO_(2)表征碳排放量,对区域碳吸收和碳排放的时空变化特征进行剖析,在此基础上构建环境碳负荷指数和脱钩弹性系数,用于解析贵州省碳收支状况及环境碳负荷与经济发展之间的脱钩关系。结果显示:(1)贵州省植被净生态系统生产力均值为257.72 g C/m^(2),呈逐步增强趋势,空间上呈现西高东低、南高北低的分布格局;岩溶碳通量的均值为6.71 t C/km^(2),年际波动较大,集中分布在研究区东北和西南部;土壤碳储量的均值为8.38 t/hm^(2),其高值区主要位于研究区南部和东部边缘;(2)区域碳排放呈现出了逐年增长的特征,表明了能源消耗的增强,形成了以城市高值区为中心向外辐射递减,各点之间以道路连通为特征的分布格局;(3)环境碳负荷指数呈逐年增长趋势,表征区域面临的环境压力越来越大,特别是在贵州省主城区出现了明显的收支不平衡,能源结构优化亟待加强;(4)综合脱钩状态整体以弱脱钩和扩张连接为主,且随时间推移脱钩状态由弱脱钩向扩张连接转变,说明环境保护滞后于经济发展,也就意味着贵州省经济的发展一定程度上牺牲了环境保护。未来应进一步强化生态修复工程的可持续性,同时发展绿色经济以促进区域生态-经济可持续发展。展开更多
We use the U.S. Navy's Master Oceanographic Observation Data Set (MOODS) forthe Yellow Sea/ East China Sea (YES) to investigate the climatological water mass features and theseasonal and non-seasonal variabilities...We use the U.S. Navy's Master Oceanographic Observation Data Set (MOODS) forthe Yellow Sea/ East China Sea (YES) to investigate the climatological water mass features and theseasonal and non-seasonal variabilities of the thermohaline structure, and use the ComprehensiveOcean-Atmosphere Data Set (COADS) from 1945 to 1989 to investigate the linkage between the fluxes(momentum, heat, and moisture) across the air-ocean interface and the formation of the water massfeatures. After examining the major current systems and considering the local bathymetry and watermass properties, we divide YES into five regions: East China Sea (ECS) shelf, Yellow Sea (YS) Basin,Cheju bifurcation (CB) zone, Taiwan Warm Current (TWC) region, Kuroshio Current (KC) region. Thelong term mean surface heat balance corresponds to a heat loss of 30 W m^(-2) in the ESC and CBregions, a heat loss of 65 W m^(-2) in the KC and TWC regions, and a heat gain of 15 W m^(-2) in theYS region. The surface freshwater balance is defined by precipitation minus evaporation. The annualwater loss from the surface for the five subareas ranges from 1.8 to 4 cm month^(-1). The freshwater loss from the surface should be compensated for from the river run-off. The entire watercolumn of the shelf region (ECS, YS, and CB) undergoes an evident seasonal thermal cycle withmaximum values of temperature during summer and maximum mixed layer depths during winter. However,only the surface waters of the TWC and KC regions exhibit a seasonal thermal cycle.. We also foundtwo different relations between surface salinity and the Yangtze River run-off, namely, out-of-phasein the East China Sea shelf and in-phase in the Yellow Sea. This may confirm an earlier study thatthe summer fresh water discharge from the Yangtze River forms a relatively shallow, low salinityplume-like structure extending offshore on average towards the northeast.展开更多
S:Understanding how surface energy fluxes respond to environmental variables and how their components vary on daily and seasonal temporal scales are critical for understanding the ecological process of wetland ecosyst...S:Understanding how surface energy fluxes respond to environmental variables and how their components vary on daily and seasonal temporal scales are critical for understanding the ecological process of wetland ecosystem. In view of the fact that studies on surface energy flux over mire in China have been very limited, we have initiated a long-term latent and sensible heat flux (two main components of the surface energy balance) observation over mire in the Sanjiang Plain from June to October in 2004 with the eddy covariance technique. Results showed that the latent and sensible heat flux had large seasonal and diurnal variation during the period of measurement. Generally, latent heat flux between the mire wetland and the atmosphere reached the maximum value in June and then gradually decreased from June to October, whose daily mean fluxes were 9.83,8.00,7.33, 4.82 and 2.04 MJ/(m^2·d), respectively. By comparison, sensible heat flux changed unnoticeably with season change from June to October, which were 1.47,0.88,1.75, 1.61,1.33 MJ/(m^2·d) respectively. The diurnal variation of both latent and sensible heat flux varied noticeably within a day. After the sunrise, the latent and sensible heat flux increased and reached the maximum at noon (11:00-13:00). Then they decreased gradually and reached the minimum value during the nighttime. The patterns of temporal variation in latent and sensible heat flux were significantly controlled by environmental factors. The latent heat flux was linearly dependent on net radiation and increased with increasing vapour pressure deficit until the vapour pressure deficit surpassed 11 hPa. Wind speed effect on latent heat flux was more complicated and, in general, showed a positive correlation between them in daytime. The sensible heat flux was controlled mainly by air temperature difference between the land surface and the overlying air. However, when the temperature difference was larger than 0.3 ℃, it had no effect on the sensible heat flux. The study showed up the temporal variation of latent and sensible heat flux and how the environmental factors affected them.展开更多
The Arctic ecosystem, especially High Arctic tundra, plays a unique role in the global carbon cycle because of amplified warming in the region. However, relatively little research has been conducted in High Arctic tun...The Arctic ecosystem, especially High Arctic tundra, plays a unique role in the global carbon cycle because of amplified warming in the region. However, relatively little research has been conducted in High Arctic tundra compared with other global ecosystems. In the present work, summertime net ecosystem exchange （NEE）, ecosystem respiration （ER）, and photosynthesis were investigated at six tundra sites （DM1-DM6） on Ny-A.lesund in the High Arctic. NEE at the tundra sites varied between a weak sink and strong source （-3.3 to 19.0 mg CO2·m-2.h-1）. ER and gross photosynthesis were 42.8 to 92.9 mg CO2·m-2·h-1 and 54.7 to 108.7 mg CO2·m-2·h-1, respectively. The NEE variations showed a significant correlation with photosynthesis rates, whereas no significant correlation was found with ecosystem respiration, indicating that NEE variations across the region were controlled by differences in net uptake of CO2 owing to photosynthesis, rather than by variations in ER. A Qm value of 1.80 indicated weak temperature sensitivity of tundra ER and its response to future global warming. NEE and gross photosynthesis also showed relatively strong correlations with C/N ratio. The tundra ER, NEE, and gross photosynthesis showed variations over slightly waterlogged wetland tundra, mesic and dry tundra. Overall, soil temperature, nutrients and moisture can be key effects on CO2 fluxes, ecosystem respiration, and NEE in the High Arctic.展开更多
Water vapour and CO2 fluxes were measured by the eddy-covariance technique above a mixed needle and broad-leaved forest with affiliated meteorological measurements in Changbai Mountain as part of China's FLUX proj...Water vapour and CO2 fluxes were measured by the eddy-covariance technique above a mixed needle and broad-leaved forest with affiliated meteorological measurements in Changbai Mountain as part of China's FLUX projects since late August in 2002. Net water vapour exchange and environmental control over the forest were examined from September 1 to October 31 in 2002. To quantify the seasonal dynamics, the transition period was separated into leafed, leaf falling and leafless stages according to the development of leaf area. The results showed that (a) seasonal variation of water vapour exchange was mainly controlled by net radiation (Rn) which could account for 78.5%, 63.4% and 56.6% for leafed, leaf falling and leafless stages, respectively, while other environmental factors' effects varied evidently; (b) magnitude of water vapour flux decreased remarkably during autumn and daily mean of water vapour exchange was 24.2 mg m-2 s-1 (100%), 14.8 mg m-2 s-1 (61.2%) and 10.3 mg m-2 s-1 (42.6%) for leafed, leaf falling and leafless stage, respectively; and (c) the budget of water vapour exchange during autumn was estimated to be 87.1 kg H2O m-2, with a mean of 1427.2 g H2O d-1' varying markedly from 3104.0 to 227.5 g H2O m-2d-1.展开更多
The present study investigates the difference in interdecadal variability of the spring and summer sensible heat fluxes over Northwest China by using station observations from 1960 to 2000. It was found that the sprin...The present study investigates the difference in interdecadal variability of the spring and summer sensible heat fluxes over Northwest China by using station observations from 1960 to 2000. It was found that the spring sensible heat flux over Northwest China was greater during the period from the late 1970s to the 1990s than during the period from the 1960s to the mid-1970s. The summer sensible heat flux was smaller in the late 1980s through the 1990s than it was in the 1970s through the early 1980s. Both the spring and summer land-air temperature differences over Northwest China displayed an obvious interdecadal increase in the late 1970s. Both the spring and summer surface wind speeds experienced an obvious interdecadal weakening in the late 1970s. The change in the surface wind speed played a more important role in the interdecadal variations in sensible heat flux during the summer, whereas the change in the land-air temperature difference was more important for the interdecadal variations in sensible heat flux in the spring. This difference was related to seasonal changes in the mean land-air temperature difference and the surface wind speed. Further analysis indicated that the increase in the spring land surface temperature in Northwest China was related to an increase in surface net radiation.展开更多
基金The National Key Basic Research Program of China under Grant No.2009CB421404the National Natural Science Foundation of China-Regional Cooperation Project under Grant No.40921160379+1 种基金the National Natural Science foundation of China under Grant No.40730951the Fundamental Research Funds for the Central Universities under Grant No.11lgjc10
文摘A singular value decomposition （SVD） analysis is carried out to reveal the relationship between the interannual variation of track and intensity of the western North Pacific tropical cyclones （WNPTCs） in the tropical cyclone （TC） active season （July–November） and the global net air-sea heat flux （Q net ） in the preceding season （April–June）. For this purpose, a tropical cyclone track and intensity function （TIF） is defined by a combination of accumulated cyclone energy （ACE） index and a cyclone track density function. The SVD analysis reveals that the first mode is responsible for the positive correlation between the upward heat flux in the tropical central Pacific and the increased activity of western North Pacific （WNP） TIF, the second mode for the positive correlation between the upward heat flux in the North Indian Ocean and the northeastward track shift of WNPTCs and the third mode for the negative correlation between the upward heat flux in mid-latitude central Pacific and the northwest displacement of the WNP TC-active center. This suggests that Q net anomalies in some key regions have a substantial remote impact on the WNP TC activity.
文摘温室效应已成为重要的全球气候问题,而内陆水体是温室气体(CO_(2)和CH_(4))的重要排放源,更有研究发现筑坝蓄水可能引起河流水体CO_(2)和CH_(4)排放的增多。为积极响应国家“双碳”目标,使用水库温室气体净排放通量评估模型G-res Tool,利用流域基本信息及水库特征数据,对澜沧江干流已建成的10座梯级水库温室气体(CO_(2)和CH_(4))进行模拟计算,10座水库蓄水后温室气体(CO_(2)和CH_(4))年排放通量平均值为162.81 g CO_(2)e/(m^(2)·a),远低于全球水库平均水平,均表现为温室气体的“源”,从上游至下游整体呈增加趋势,且排放以CO_(2)为主,全年CO_(2)排放通量为CH_(4)的36倍。考虑了水库蓄水前的温室气体排放及其他非相关人类活动的影响后,得到澜沧江水库温室气体(CO_(2)和CH_(4))年净排放通量平均值为225.70 g CO_(2)e/(m^(2)·a),表明筑坝增加了库区水体温室气体排放,但和火力发电相比,仍属于相对清洁能源。
文摘贵州省是我国喀斯特生态系统的典型分布区,生态敏感且脆弱,同时其也曾是我国的连片特困区,经济发展愿望迫切。对区域环境-经济发展状况及相互作用关系进行研究具有重要意义。研究从植被净生态系统生产力、土壤碳储量、岩溶碳通量三方面计算了贵州省陆地生态系统碳吸收,以能源燃烧排放的CO_(2)表征碳排放量,对区域碳吸收和碳排放的时空变化特征进行剖析,在此基础上构建环境碳负荷指数和脱钩弹性系数,用于解析贵州省碳收支状况及环境碳负荷与经济发展之间的脱钩关系。结果显示:(1)贵州省植被净生态系统生产力均值为257.72 g C/m^(2),呈逐步增强趋势,空间上呈现西高东低、南高北低的分布格局;岩溶碳通量的均值为6.71 t C/km^(2),年际波动较大,集中分布在研究区东北和西南部;土壤碳储量的均值为8.38 t/hm^(2),其高值区主要位于研究区南部和东部边缘;(2)区域碳排放呈现出了逐年增长的特征,表明了能源消耗的增强,形成了以城市高值区为中心向外辐射递减,各点之间以道路连通为特征的分布格局;(3)环境碳负荷指数呈逐年增长趋势,表征区域面临的环境压力越来越大,特别是在贵州省主城区出现了明显的收支不平衡,能源结构优化亟待加强;(4)综合脱钩状态整体以弱脱钩和扩张连接为主,且随时间推移脱钩状态由弱脱钩向扩张连接转变,说明环境保护滞后于经济发展,也就意味着贵州省经济的发展一定程度上牺牲了环境保护。未来应进一步强化生态修复工程的可持续性,同时发展绿色经济以促进区域生态-经济可持续发展。
文摘We use the U.S. Navy's Master Oceanographic Observation Data Set (MOODS) forthe Yellow Sea/ East China Sea (YES) to investigate the climatological water mass features and theseasonal and non-seasonal variabilities of the thermohaline structure, and use the ComprehensiveOcean-Atmosphere Data Set (COADS) from 1945 to 1989 to investigate the linkage between the fluxes(momentum, heat, and moisture) across the air-ocean interface and the formation of the water massfeatures. After examining the major current systems and considering the local bathymetry and watermass properties, we divide YES into five regions: East China Sea (ECS) shelf, Yellow Sea (YS) Basin,Cheju bifurcation (CB) zone, Taiwan Warm Current (TWC) region, Kuroshio Current (KC) region. Thelong term mean surface heat balance corresponds to a heat loss of 30 W m^(-2) in the ESC and CBregions, a heat loss of 65 W m^(-2) in the KC and TWC regions, and a heat gain of 15 W m^(-2) in theYS region. The surface freshwater balance is defined by precipitation minus evaporation. The annualwater loss from the surface for the five subareas ranges from 1.8 to 4 cm month^(-1). The freshwater loss from the surface should be compensated for from the river run-off. The entire watercolumn of the shelf region (ECS, YS, and CB) undergoes an evident seasonal thermal cycle withmaximum values of temperature during summer and maximum mixed layer depths during winter. However,only the surface waters of the TWC and KC regions exhibit a seasonal thermal cycle.. We also foundtwo different relations between surface salinity and the Yangtze River run-off, namely, out-of-phasein the East China Sea shelf and in-phase in the Yellow Sea. This may confirm an earlier study thatthe summer fresh water discharge from the Yangtze River forms a relatively shallow, low salinityplume-like structure extending offshore on average towards the northeast.
文摘S:Understanding how surface energy fluxes respond to environmental variables and how their components vary on daily and seasonal temporal scales are critical for understanding the ecological process of wetland ecosystem. In view of the fact that studies on surface energy flux over mire in China have been very limited, we have initiated a long-term latent and sensible heat flux (two main components of the surface energy balance) observation over mire in the Sanjiang Plain from June to October in 2004 with the eddy covariance technique. Results showed that the latent and sensible heat flux had large seasonal and diurnal variation during the period of measurement. Generally, latent heat flux between the mire wetland and the atmosphere reached the maximum value in June and then gradually decreased from June to October, whose daily mean fluxes were 9.83,8.00,7.33, 4.82 and 2.04 MJ/(m^2·d), respectively. By comparison, sensible heat flux changed unnoticeably with season change from June to October, which were 1.47,0.88,1.75, 1.61,1.33 MJ/(m^2·d) respectively. The diurnal variation of both latent and sensible heat flux varied noticeably within a day. After the sunrise, the latent and sensible heat flux increased and reached the maximum at noon (11:00-13:00). Then they decreased gradually and reached the minimum value during the nighttime. The patterns of temporal variation in latent and sensible heat flux were significantly controlled by environmental factors. The latent heat flux was linearly dependent on net radiation and increased with increasing vapour pressure deficit until the vapour pressure deficit surpassed 11 hPa. Wind speed effect on latent heat flux was more complicated and, in general, showed a positive correlation between them in daytime. The sensible heat flux was controlled mainly by air temperature difference between the land surface and the overlying air. However, when the temperature difference was larger than 0.3 ℃, it had no effect on the sensible heat flux. The study showed up the temporal variation of latent and sensible heat flux and how the environmental factors affected them.
基金supported by the National Natural Science Foundation of China (Grant nos.41576181 and 41176171)Specialized Research Fund for the Doctoral Program of Higher Education (Grant no.20123402110026)
文摘The Arctic ecosystem, especially High Arctic tundra, plays a unique role in the global carbon cycle because of amplified warming in the region. However, relatively little research has been conducted in High Arctic tundra compared with other global ecosystems. In the present work, summertime net ecosystem exchange （NEE）, ecosystem respiration （ER）, and photosynthesis were investigated at six tundra sites （DM1-DM6） on Ny-A.lesund in the High Arctic. NEE at the tundra sites varied between a weak sink and strong source （-3.3 to 19.0 mg CO2·m-2.h-1）. ER and gross photosynthesis were 42.8 to 92.9 mg CO2·m-2·h-1 and 54.7 to 108.7 mg CO2·m-2·h-1, respectively. The NEE variations showed a significant correlation with photosynthesis rates, whereas no significant correlation was found with ecosystem respiration, indicating that NEE variations across the region were controlled by differences in net uptake of CO2 owing to photosynthesis, rather than by variations in ER. A Qm value of 1.80 indicated weak temperature sensitivity of tundra ER and its response to future global warming. NEE and gross photosynthesis also showed relatively strong correlations with C/N ratio. The tundra ER, NEE, and gross photosynthesis showed variations over slightly waterlogged wetland tundra, mesic and dry tundra. Overall, soil temperature, nutrients and moisture can be key effects on CO2 fluxes, ecosystem respiration, and NEE in the High Arctic.
基金Knowledge Innovation Project of CAS,No.KZCX1-SW-01-01A
文摘Water vapour and CO2 fluxes were measured by the eddy-covariance technique above a mixed needle and broad-leaved forest with affiliated meteorological measurements in Changbai Mountain as part of China's FLUX projects since late August in 2002. Net water vapour exchange and environmental control over the forest were examined from September 1 to October 31 in 2002. To quantify the seasonal dynamics, the transition period was separated into leafed, leaf falling and leafless stages according to the development of leaf area. The results showed that (a) seasonal variation of water vapour exchange was mainly controlled by net radiation (Rn) which could account for 78.5%, 63.4% and 56.6% for leafed, leaf falling and leafless stages, respectively, while other environmental factors' effects varied evidently; (b) magnitude of water vapour flux decreased remarkably during autumn and daily mean of water vapour exchange was 24.2 mg m-2 s-1 (100%), 14.8 mg m-2 s-1 (61.2%) and 10.3 mg m-2 s-1 (42.6%) for leafed, leaf falling and leafless stage, respectively; and (c) the budget of water vapour exchange during autumn was estimated to be 87.1 kg H2O m-2, with a mean of 1427.2 g H2O d-1' varying markedly from 3104.0 to 227.5 g H2O m-2d-1.
基金supported by the National Natural Science Foundation of China (Grant No. 40730952)the National Basic Research Program of China (Grant No. 2009CB421405)the Program of Knowledge Innovation for the third period, the Chinese Academy of Sciences (Grant No. KZCX2-YW-220), and IAP07414
文摘The present study investigates the difference in interdecadal variability of the spring and summer sensible heat fluxes over Northwest China by using station observations from 1960 to 2000. It was found that the spring sensible heat flux over Northwest China was greater during the period from the late 1970s to the 1990s than during the period from the 1960s to the mid-1970s. The summer sensible heat flux was smaller in the late 1980s through the 1990s than it was in the 1970s through the early 1980s. Both the spring and summer land-air temperature differences over Northwest China displayed an obvious interdecadal increase in the late 1970s. Both the spring and summer surface wind speeds experienced an obvious interdecadal weakening in the late 1970s. The change in the surface wind speed played a more important role in the interdecadal variations in sensible heat flux during the summer, whereas the change in the land-air temperature difference was more important for the interdecadal variations in sensible heat flux in the spring. This difference was related to seasonal changes in the mean land-air temperature difference and the surface wind speed. Further analysis indicated that the increase in the spring land surface temperature in Northwest China was related to an increase in surface net radiation.
