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A westward 6 day oscillation with zonal wave number 1 is identified in the global maps of the ionospheric total electron content (TEC) during May 2003. This signature coincides with the wave activities in the mesosphere and lower thermosphere (MLT) region with a similar zonal structure and period, deduced from the temperature and wind observations from the Thermosphere Ionosphere and Mesosphere Electric Dynamics (TIMED) satellite. The vertical wavelength of this 6 day wave is estimated to be~65 km, which enables it to propagate up into the lower thermosphere and therefore modulate the ionosphere through E region wind dynamo. The zonal wind perturbations of the 6 day wave maximize in the equatorial region with an amplitude of~30 m/s and the meridional wind perturbations peak at middle latitudes with an amplitude of 15-20 m/s. The 6 day oscillation in TEC peaks at the geomagnetic equatorial ionization anomaly (EIA) crests in both hemispheres with a deep minimum at the equator. The absolute TEC perturbations maximize at~1400-1800 LT with an amplitude of~9 (~7) total electron content unit (TECU; 1 TECU = 10 16 m À2 ) in the southern (northern) hemisphere, which account for~16% (~10%) of the background TEC. Larger relative TEC perturbations of~20% are found at 0200-0400 LT. The similar wave number-period spectra and the consistent temporal variations of the 6 day periodical signatures in both neutral atmosphere and ionosphere suggest a strong neutral-ion coupling through planetary wave.

Herzberg staining, a quick and convenient tool for distinguishing non‐wood fibers from wood pulp, and Raman spectroscopy were employed to investigate three paper currencies issued under the reign of the Chinese Ming and Qing Emperors between 15th and 19th centuries ‐ da ming bao chao (AMS C‐14 Date: 1410‐1435 AD, ±1σ) from the Early Ming Dynasty (1405–1433 AD) and da qing bao chao (1859 AD) and hu bu guan piao (1854–1858 AD) from the Late Qing Dynasty (1840–1911 AD). Fiber staining and microscopic examination revealed a predominance of bast fiber from probably mulberry trees and very few cotton fibers (supposed to be environment contamination) in da ming bao chao; fibers in da qing bao chao and hu bu guan piao turned out to be quite pure, which are also bast fibers but very likely came from ramie and paper mulberry trees, respectively. Raman analysis of red, blue, and black pigments on the investigated paper currencies showed that: (1) The reddish seal on da ming bao chao is not a vermilion (HgS) paste, as it is traditionally assumed, but instead a red lead (or minium, Pb3O4) one. The red pigments on both da qing bao chao and hu bu guan piao are vermilion (HgS). (2) Prussian blue (Fe7(CN)18⋅14‐16H2O), a Western pigment, was identified as blue on both da qing bao chao and hu bu guan piao. (3) The black pigment on all these three paper currencies is amorphous carbon from soot. (4) Raman analysis of evenly distributed white pigment particles among the fibers in da qing bao chao confirmed the use of calcium carbonate (CaCO3) as coating pigment or fillers. Both microscopic examination of stained fibers and Raman analysis allowed, for the first time, the understanding of fiber and pigment use in producing ancient Chinese paper currencies. Copyright © 2013 John Wiley & Sons, Ltd.

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