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在华北玉米生育期观测的16 m高度CO2浓度及通量特征 总被引：7，自引：1，他引：7
利用中国气象局固城农业气象生态试验站2004年玉米生育期通量观测资料，分析了CO2浓度和通量随玉米生长的变化，并估算了玉米生育期陆地与大气CO2净交换量。结果表明:CO2浓度变化对农户活动和作物生长极其敏感；浓度在整个生育期始终有明显的日变化规律，峰值（谷值）出现在日出（日落）前后，通量仅在7月中旬至10月上旬之间出现明显的日变化特点，且位相超前于浓度，开花期通量最大；玉米播种期、苗期和成熟后地面向大气净排放碳， 拔节至成熟前地面从大气净吸收碳；开花期碳吸收最强，其后依次为吐丝－乳熟期和拔节期。比较分析了目前流行的通量计算方法对碳吸收估计的影响，结果显示不同计算方法能产生高达160%的碳吸收估计偏差，应当引起重视。生态系统碳平衡分析结果表明，玉米地在生长季表现为弱碳汇（大约660 kg/hm2），但这一结果可能低估了实际的碳汇强度，低估程度有待研究。 相似文献
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Cai-Qing Guo Ryszard Ochyra Peng-Cheng Wu Rodney D. Seppelt Yi-Feng Yao Lin-Gen Bian Su-Ping Li Cheng-Sen Li 《Climatic change》2013,119(2):407-419
The moss, Warnstorfia exannulata (Schimp.) Loeske, was first reported forming a carpet beside a water pool in Ny-Ålesund (78°56′N), Svalbard in 1959. Fifty years later, in 2008, it was found growing as an aquatic in a pool. The moss is sensitive to seasonal changes and exhibits a pattern of seasonal growth: summer stems with densely arranged leaves and lateral branches, and winter growth with short-leaved stems and no lateral branch. The mean daily increase in stem length is 0.68 mm in summer and 0.07 mm in winter. The longest specimens were up to 8 years old. The growth of the moss reflects closely seasonal temperature and growth conditions. World distribution is discussed and global distribution mapped. 相似文献
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在参考国内外卫星遥感反演地表反照率方法的基础上，提出了一种反演多云地区地表反照率的新方法，称之为组合反演法。对于受云影响而无法获得足够的晴空观测数据的像素点，在遥感地表分类数据和归一化植被指数（NDVI） 数据的辅助下，在其周围的有限范围内选择与其具有相同BRDF形状的像素点，将它们在观测角度上互为补充的晴空观测数据组合成对同一个BRDF形状的一组多角度观测数据，达到一定数量后直接利用线性的RossThick-LiSparse互易核驱动模型反演二向反射分布函数（BRDF）参数。然后，根据“16天”期间平均的当地正午太阳高度角计算反照率。选择青藏高原地区2004年6～8月间5组“16天”的Terra MODIS数据进行的反演试验表明，该方法不仅具有反演多云地区地表反照率的能力，而且能够更好地反映实际的地表信息，反演结果的精度与美国MOD43产品的精度相当。 相似文献
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南极海冰与温度变化关系的统计分析(英) 总被引：3，自引：0，他引：3
Temporal-spatial characteristics of Antarctic surface air temperature and sea ice variations have been statistically analyzed. Results show that, during the last 30 years there was an obvious warming trend in Antarctica, but there exists substantial difference in different sectors and different period. The most significant warming trend occurred in the Antarctic Peninsula, about 2-3 times greater than that in the whole east Antarctica. In recent 20 years the correlation between Antarctic mean temperature and mean sea ice area is low and insignificant, but its linear trends are found to be opposite related in each sector, that is, sea ice extent reductions when temperatures are high. The different climate sectors defined by cluster analysis clearly show a close relationship between two parameters on the inter-seasonal time scale. The most sensitive correlation sectors found are from south Atlantic to southwest Pacific ocean. 相似文献
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