UV extinction in the atmosphere and its spatial variation in North China

- The ultraviolet radiation under all skies was studied in North China.
- An important phenomenon of UV utilization by “water vapor factor” was studied.
- UV are absorbed indirectly once they react OH, H2O and consumed directly by GLPs.
- This mechanism controls atmospheric basic processes and affects the atmosphere.
- More studies of UV utilization by atmospheric GLPs and its application are needed.

It is important to determine the distribution of solar radiation between the top of the atmosphere and the surface. Based on an empirical model for estimating hourly ultraviolet radiation irradiance (UVI) under all sky conditions in North China, UVI at the surface and at the top of the atmosphere were obtained. An important phenomenon of UV utilization by “water vapor or absorbing factor” in the 290-400 nm range was studied, its mechanism was that UV energy can be absorbed indirectly once they react OH radicals and H2O and/or consumed directly by gases, liquids, particles (GLPs). The UVI loss in the atmosphere contributed by “absorbing” and scattering materials were 19.30 and 35.31 W m−2, respectively, which depend on the region and season. The energy loss related to the “absorbing substances” would exist in other regions and should be considered in models (e.g., radiative transfer, chemistry and photochemistry, climate) for better understanding the basic processes in the atmosphere.