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- Semadeni Davies, Annette, et al.
(författare)
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Estimating latent heat over a melting arctic snow cover
- 2004
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Ingår i: Nordic Hydrology. - 0029-1277. ; 35:3, s. 175-190
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Tidskriftsartikel (refereegranskat)abstract
- The latent heat flux over snow near Ny-Alesund, Spitsbergen, was investigated for the 1999 snowmelt season to assess different methods of modelling the flux. Snow evaporation had hitherto been estimated as the residual of plot water balance calculations and was subject to measurement errors: hence a modelling solution was sought to make use of existing data. Precipitation, snow depth and albedo we.-e measured daily. Runoff from the plots was recorded continuously. Wind speed, relative humidity and air temperature were measured at two levels (2 and 10 m) every 10 minutes; wind direction was noted hourly. Three models which simulate latent heat were assessed against evaporation and condensation measured by weighing several snow-filled containers each day. Two employ the bulk profile method (within the SNTHERM and CROCUS snowmelt models), while the third is the aerodynamic profile method (APM). Each follows tie measured evaporation until snow-free patches develop after which the APM predicts evaporation whereas the snowmelt models predict condensation. The effect of wind is also noted. A major conclusion of this work is that the complexity of the land surface/atmosphere interactions, particularly when the snow cover breaks up, precludes the use of simple models for determining latent heat.
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| 2. |
- Takahashi, M., et al.
(författare)
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Oxygen annealing effect of photoelectron spectra in SrBi2Ta2O9 film
- 2002
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 41:11B, s. 6797-6802
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Tidskriftsartikel (refereegranskat)abstract
- Photoelectron spectra have been studied to clarify O-2-annealing effects on the band diagram of the metal-SrBi2Ta2O9 (SBT) junction and ionization energy of SBT films deposited by the pulsed laser, deposition (PLD) method. Photoemission spectra obtained by ultraviolet light irradiation have a threshold of 5.90 eV for the as-deposited SBT film and 5.56 eV for the O-2-annealed one. This shift of the threshold indicates that the annealing treatment has increased the Fermi level by 0.34 eV. On the assumption of a 4.2 eV band gap and 3.5 eV electron affinity for the SBT, as-deposited SBT has been estimated to give a 0.60 eV lower barrier height for holes than that for electrons, which is possibly because of, insufficiently oxidized (Bi2O2)(2+) layers as indicated by X-ray photoelectron spectroscopy (XPS). After annealing in O-2, however, barrier height energies for holes and electrons become closer to each other. These results agree with our previous studies which have reported that the O-2-annealing suppressed the leakage current through SBT and improved the retention characteristics of the metal-ferroelectric-insulator-semiconductor structure.
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