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The impact of new water vapour spectral line parameters on the calculation of atmospheric absorption
Author(s) -
Zhong Wenyi,
Haigh Joanna D.,
Belmiloud Djedjiga,
Schermaul Roland,
Tennyson Jonathan
Publication year - 2001
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49712757508
Subject(s) - zenith , water vapor , solar zenith angle , spectral line , line (geometry) , atmospheric sciences , sky , absorption (acoustics) , infrared , absorption spectroscopy , materials science , environmental science , computational physics , meteorology , physics , optics , geometry , mathematics , astronomy
New laboratory measurements and theoretical calculations of integrated line intensities for water vapour bands in the near‐infrared and visible regions (8600–15 000 cm −1 ) show a systematic 6–26% increase in band intensities compared to the HITRAN96 database. We have used the GENLN2 line‐by‐line code to assess the effects of such changes in the water vapour spectral database on calculations of clear‐sky short‐wave fluxes and heating rates. Three standard atmospheres were used and it was found that, compared with HITRAN96 results, the absorbed downward solar fluxes increase (including the effects of theoretically predicted weak water lines in the region) by 5.5, 4.8 and 2.2 W m −2 (solar zenith angle = 30°) and by 2.4, 2.1 and 1.1 W m −2 (solar zenith angle = 75°) respectively. The maximum change in heating rate is about 4%. The effects are about five to eight times larger than those produced by using the Giver et al. corrections. The combined effects of the revised description of the spectroscopy of water vapour account for approximately 30–90% of the absorption currently ascribed to the water vapour continuum in this spectral region.