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21.
MAXIM OGURTSOV HOGNE JUNGNER MARKUS LINDHOLM 《Geografiska Annaler: Series A, Physical Geography》2007,89(2):129-136
Six millennial proxy records of temperature in the northern hemisphere were analysed using both the Fourier and wavelet approaches. We found that the analysed temperature proxies have appreciable synchrony at multidecadal and centennial time scales. These data also show evidence for the presence of a roughly regular large‐scale rhythm with a periodicity of 50–130 years in the climate of the northern hemisphere over the last millennium. It is shown that the amplitude of this variation might reach 0.20–0.28°C and contribute appreciably to the rise of global temperature over the first part of the 20th century. Possible origins of the global centennial climatic cycles are discussed. 相似文献
22.
Saharan dust absorption and refractive index from aircraft-based observations during SAMUM 2006 总被引:1,自引:0,他引:1
By ANDREAS PETZOLD KATHARINA RASP BERNADETT WEINZIERL MICHAEL ESSELBORN THOMAS HAMBURGER REAS DÖRNBRACK KONRAD KANDLER LOTHAR SCHÜTZ PETER KNIPPERTZ MARKUS FIEBIG AKI VIRKKULA 《Tellus. Series B, Chemical and physical meteorology》2009,61(1):118-130
During the Saharan Mineral Dust Experiment (SAMUM) conducted in summer 2006 in southeast Morocco, the complex refractive index of desert dust was determined from airborne measurements of particle size distributions and aerosol absorption coefficients at three different wavelengths in the blue (467 nm), green (530 nm) and red (660 nm) spectral regions. The vertical structure of the dust layers was analysed by an airborne high spectral resolution lidar (HSRL). The origin of the investigated dust layers was estimated from trajectory analyses, combined with Meteosat 2nd Generation (MSG) scenes and wind field data analyses. The real part n of the dust refractive index was found almost constant with values between 1.55 and 1.56, independent of the wavelength. The values of the imaginary part k varied between the blue and red spectral regions by a factor of three to ten depending on the dust source region. Absolute values of k ranged from 3.1 × 10−3 to 5.2 × 10−3 at 450 nm and from 0.3 × 10−3 to 2.5 × 10−3 at 700 nm. Groupings of k values could be attributed to different source regions. 相似文献