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41.
We compare vertical gradients of sunspot magnetic fields which were derived for the first time from nearly simultaneous vector magnetograms. The measurements were obtained in the photospheric lines Fe I 5250 and Fe I 5253 by the vector magnetographs of the Sayan-Observatory (Irkutsk) and the Solar Observatory “Einsteinturm”. The gradients derived from the different measurements show a good correspondence with respect to the numerical values as well as to the morphological structure of the distributions in the magnetograph's field of view. In the umbral region of the spot the vertical gradients amount to about 0.32 Gkm-1 indicating that the umbral field can extend with strong field strengths into chromosphere and corona. A circle-like area with opposite sign to the umbral gradient was found on the boundary between penumbra and surrounding photosphere. The physical significance of this area should be the goal of further observations and interpretations. Wir vergleichen Vertikalgradienten des Magnetfeldes von Sonnenflecken, die erstmals aus fast simultan aufgenommenen Vektormagnetogrammen abgeleitet wurden. Die Messungen erfolgten unter Verwendung der photosphärischen Linien Fe I 5250 Å und Fe I 5253 Å mit den Vektormagnetografen des Sayan-Observatoriums (Irkutsk) und des Sonnenobservatoriums “Einsteinturm”. Die aus den verschiedenen Messungen ermittelten Gradienten zeigen sowohl hinsichtlich der numerischen Werte als auch bezüglich der morphologischen Struktur ihrer Verteilung im Bildfeld der Magnetografen eine gute Übereinstimmung. Im Kern des Flecks erreicht der Vertikalgradient 0,32 g kin-1. Das weist darauf hin, daß sich das umbrale Feld mit hoher Feldstärke bis in die Chromosphäre und Korona erstrecken kann. Ein kreisförmiges Gebiet mit entgegengesetztem Vorzeichen zum umbralen Gradienten ist an der Grenze zwischen Penumbra und umgebender Photosphäre zu finden. Die physikalische Bedeutung dieses Gebietes soll durch weitere Beobachtungen und Auswertungen geklärt werden. 相似文献
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In this work, enhanced poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) bulk-heterojunction photovoltaic devices are achieved via slow-solvent-vapour treatment. The correlations between the morphology of the active layer and the photovoltaic performance of polymer-based solar cell are investigated. The active layers are characterized by atomic force microscopy and optical absorption. The results show that slow-solvent-vapour treatment can induce P3HT self-organization into an ordered structure, leading to the enhanced absorption and efficient charge transport. 相似文献
46.
Hajer Khemakhem Jannet Elloumi Mahmoud Moussa Lotfi Aleya Habib Ayadi 《Estuarine, Coastal and Shelf Science》2010
The distribution of phytoplankton abundance, biomass and species composition coupled with environmental factors and metazooplankton was studied relatively intensively and over a period of four consecutive years in five ponds featuring a gradient of increasing salinity from near to that of sea water to a nine-fold concentration from 2000 to 2003. The results indicate that the physical characteristics of the water (temperature and salinity) were quite similar over the years. Nutrients, which were concentrated in pond A1, decreased with increases in salt concentration. The composition of the phytoplankton community showed strong seasonality. Diatoms dominated in the first ponds A1, A16 and C2-1, followed by dinoflagellates. Chlorophyceae dominated the phytoplankton community in the hypersaline ponds M2 and TS. Cyanobacteriae were relatively abundant in ponds M2 and TS. The highest phytoplankton density and biomass were found in the ponds with the highest salinity due to the proliferation of Dunaliella salina (Chlorophyta: Volvocales). The inter-annual study of phytoplankton succession in the Sfax solar salterns showed slight differences among the years of study due to the stability of the environmental conditions. Phytoplankton communities were permanently primitive, stage 1 – structured as they failed to build complexity because of salt stress which operates for longer and above any other variables. This reduced frequency of disturbance to the existing course of regulation, allowed the community to “mature” from its “primitive” state, rather than experience frequent structural setbacks. 相似文献
47.
渤海海冰中太阳辐射的光谱特征观测研究 总被引:7,自引:2,他引:5
通过采用多光谱仪器,对渤海营口港一带的近岸固定冰进行了3个站位11个谱段的入射辐射、反射辐射和透射辐射随时间变化过程的观测和研究。结果表明,发生在海冰中的反射辐射和透射辐射与入射太阳辐射的谱分布有明显差别,而且有显著的日变化。文章确立了入射辐射、反射辐射和透射辐射随时间的变化与太阳高度角的正弦成精确的线性关系,海冰的积分反照率与太阳高度角的正弦满足二次函数关系,可将不同时刻的观测值归算到正午时刻的辐射值,使不同时刻的观测结果具有可比性。计算结果表明,海冰只衰减特定强度的辐射,衰减量与入射辐射光谱分布以及辐射的强度无关,导致绿光的透射辐射最强。该文是对渤海海冰透射辐射的初步尝试,所获得的结果对未来大范围海冰光学观测打下了基础。 相似文献
48.
Jannet Elloumi Jean-François CarriasHabib Ayadi Télesphore Sime-NgandoAbderrahmen Bouaïn 《Estuarine, Coastal and Shelf Science》2009
The composition and distribution of the main planktonic halophilic micro-organisms (heterotrophic and autotrophic picoplankton, nanoplankton, phytoplankton, ciliates) and metazooplankton were investigated in six ponds of increasing salinity in the solar salt works of Sfax, Tunisia, from January to December 2003. Marked changes in the composition and biomass of the communities were found along the salinity gradient, especially at salinities of 150 and 350. Autotrophic picoplankton, nanoplankton, diatoms, dinoflagellates and ciliates characterized the less salted ponds. Planktonic biomass was the highest at intermediate salinity as a consequence of a bloom of Ochromonas. Species richness of phytoplankton, ciliates and zooplankton greatly decrease above a salinity of 150 and typical halophiles (Dunaliella salina, cyanobacteria, Fabrea salina and Artemia salina) were found between 150 and 350 salinity. In this environment, F. salina appeared more adapted than the brine shrimp to survive during phytoplankton blooms. The halophilic plankton was however almost entirely composed of heterotrophic prokaryotes in the crystallizers. We thus observed a progressive disappearance of the autotrophic planktonic communities along the salinity gradient. Multivariate analysis of the communities provides evidence that ponds represent discrete aquatic ecosystems within this salt works. 相似文献
49.
The study of Mg isotopes has been carried out for about 40 years since 1970 s. With analytical progress, the study is not only limited to the excess of 26Mg due to decay of short-lived 26Al in primitive meteorites, also extended to mass-dependent fractionation of Mg isotopes in meteorites and terrestrial rocks. This paper reviews recent development in Mg isotope researches. 相似文献
50.
影响人体体感温度的气象要素主要包括温度、湿度、风以及太阳辐射,依据这些气象要素影响人体体感温度的原理,确定了平均气温与体感温度相同时的临界相对湿度、风速及太阳辐射值.以全国有水平面直接辐射曝辐量观测项目的77个气象台站的历年逐日4次定时观测资料为基础,把相邻两个白昼(夜间)的气温差作为因变量,相对湿度差、风速差、垂直辐射差(白昼)作为自变量,以旬为时问分辨率,建立了逐旬多元回归方程.各地所建立的逐句多元线性拟合方程拟合优度相当高,F统计量检验也充分证明线性回归方程总体成立,从气候意义、统计角度来看该方法都具有充分的可行性. 相似文献