Assessment of the Impact of Solar Spectral Irradiance on Near-Infrared Clear-Sky Atmospheric Absorption and Heating Rates

摘要

In the near infrared (near IR), differences in both the absolute level and spectral resolution of available observation-based solar spectral irradiances (SSI) are very significant. In this paper, a very high-resolution line-by-line radiative transfer model has been used to investigate the effect of the differences in the absolute level of SSI on the clear-sky total absorbed solar irradiance and solar heating rates in the near IR from 4,000 to 10,000 cm~(-1) (2.5–1 μm), for a midlatitude summer atmosphere. Absorption calculated using observed SSI from the surface, aircraft, and satellite are between 2 and 8% lower than that for the widely used ATmospheric Laboratory for Applications and Science (ATLAS) 3 spectrum. Tropospheric and stratospheric heating rates produce by these spectra are also lower than that produced by the ATLAS 3 spectrum by about 3–9% and 4–11%, respectively. However, there is a closer agreement between near IR absorbed irradiances and heating rates computed using two most recent observed spectra. That notwithstanding, it is recommended that the uncertainty in the choice of the SSI in near IR radiative transfer modeling should be quantified.