Spectroscopic information on atmospheric gases, such as absorption line positions,
intensities and widths, is important for radiative transfer calculations in climate and
weather models. The widely used HIgh resolution TRANsmission (HITRAN) spectroscopic
database is updated regularly. A line-by-line radiative transfer model has
been used to investigate the impacts of the updates of HITRAN from 2008 to 2016
on clear-sky calculations of absorption and solar heating rates in the near-infrared
region from 4,000 to 10,000 cm−1 (1.0–2.5 μm). These calculations were carried
out for the tropical and sub-arctic atmospheres at solar zenith angles of 30◦ and 75◦
using HITRAN absorption line parameters for H2O, CO2, O3, N2O, CO, CH4 and
O2 as well as the MT_CKD 2.5 (Mlawer-Tobin-Clough-Kneizys-Davies) continua
for H2O, CO2, O3 and O2. It was found that the improvements in HITRAN absorption
line parameters led to modest increases in the spectrally integrated absorbed
downward solar fluxes and heating rates. The differences in absorbed fluxes are
larger between HITRAN2016 and HITRAN2008 (maximum difference ∼1.3%) than
between HITRAN2016 and HITRAN2012 (largest difference ∼0.3%). The corresponding
maximum differences in heating rates are less than 2%. In order to improve
accuracy, HITRAN2016 should be used in preference to earlier line-lists for calculating
near-infrared absorbed solar fluxes and heating rates; but for calculations
of clear-sky heating rates in the near-infrared region that do not require better than
2% accuracy, line parameters from HITRAN2012 and HITRAN2008 may still be
used. Although the revisions of HITRAN led to relatively small differences in the
spectrally integrated quantities, the improved quality of near-infrared line parameters
will have a significant impact on other atmospheric applications such as the
measurements of CO2 concentrations at a precision of less than 1% in Greenhouse
Gases Observatory Satellite (GOSAT) and Orbiting Carbon Observatory-2 (OCO-2)
missions.
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