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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 10,000cm(-1) (2.5-1m), 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.

Plain Language Summary There have been disagreements in the measurement of the amount of solar energy arriving outside the Earth's atmosphere as infrared, a region with a significant quantity of solar energy. But very little attention has been paid to the effect of these differences in climate modeling. This work examines the impact that the differences in this infrared solar energy have on its absorption by the atmosphere and subsequent heating of the atmosphere by gases such as water vapor and carbon dioxide. Results show that the differences in this infrared solar energy lead to significant differences in absorbed solar energy and heating of the atmosphere. Compared with older measurements of the infrared solar energy, calculations using two recent measurements produce comparable absorption in the atmosphere as well as heating of the atmosphere. This can be interpreted as a good sign that disagreements in measurements of infrared solar energy are decreasing, but some caution should be taken when choosing a measured infrared solar energy for climate simulations.