Search

We present an analysis of spatial and temporal spectra of the observations of scintillations in a laser beam (532 nm, ∼200  mW power) traveling along a 144 km path at an altitude of 2–2.4 km above sea level, just above the atmospheric boundary layer, between the islands of La Palma and Tenerife. The observations were performed during nighttime on July 18 and 21, 2011, by means of a telescope with an aperture diameter of 1 m. Strong scintillations were observed. We compared the temporal and spatial spectra of the scintillations. For the temporal spectra, we performed the correction for the aliasing effect due to the low frame rate. The 2D spatial spectra of the scintillations in the observation plane were found to be close to isotropic. This allowed for transforming them into 1D spectra. We found a good agreement between the temporal and 1D spatial spectra. This corroborates the applicability of the Taylor hypothesis of frozen turbulence for finite-size laser beams and strong scintillations.

We analyzed the observations of scintillations in a laser beam (532 nm, ∼200  mW power) traveling along a 144 km path at an altitude of 2.2–2.4 km above sea level, just above the atmospheric boundary layer, between the islands of La Palma and Tenerife. The observations were performed during nighttime on 18 July 2011, by means of a telescope with an aperture diameter of 1 m. Strong scintillations were observed. The estimates of spatial spectra and correlation functions indicated that the observed intensity fields possess, statistically, a locally isotropic structure, which agrees with the idea of a locally isotropic turbulence. The estimates of spatial autospectra and autocorrelation functions of the intensity field indicated that the characteristic scale of the internal structure of the observed clusters is 6.5–8 mm, while the characteristic size of the clusters is 4–5 cm. The major contribution to the observed scintillations comes from the inhomogeneities of the intensity field with scales from 1–2 cm up to 10–12 cm. The analysis of the cross-spectra indicated that the hypothesis of frozen turbulence introduced by Taylor can be used for the description of spatiotemporal structure of intensity fluctuations of laser beams traveling through long paths in the atmosphere.

The infrared spectrum of sunspots is analyzed in the H-band region (5540-6997 cm-1) with the aid of a new, hot (T = 1800 K) laboratory emission spectrum of water covering 4878-7552 cm-1. There are 682 lines in the sunspot spectrum and 5589 lines in the laboratory spectrum assigned quantum numbers corresponding to transitions due to H216O using a combination of previously known experimental energy levels for water and variational line lists. A further 201 unassigned lines common to both spectra can also be associated with water.

For Abstract see ChemInform Abstract in Full Text.