THE ATACAMA SURFACE SOLAR MAXIMUM

We have presented a descriptive analysis showing a suite of different global products that combine information from models and satellites to provide the global distribution of surface total solar radiation as well as the distribution of the main substances that explain the atmospheric extinction of solar radiation reaching the surface. Latitude, elevation, cloud fraction, water vapor, and aerosols have a first-order influence on the distribution of surface solar radiation over the planet, and no single factor explains the combined distribution. The most likely location of the total solar radiation over the surface of the planet is on the pre-Andean Domeyko Cordillera, a mountain range with elevations between 3,500 and 5,000 m. The regional climate of the Atacama is such that extremely low values of water vapor, cloud cover, ozone, and aerosols concur in this region. The atmospheric transparency in the visible and infrared provided by these conditions, together with a relatively high elevation and low latitude, conspire to produce a region where mean total radiation values exceed 300 W m-2. According to a semiempirical model for surface solar radiation that takes into account extinction by gases, clouds, aerosols, and the effect of topography, the maximum is about 310 ± 15 W m-2, although for individual years, especially those with dry summertime Altiplano conditions, the solar maximum should be located in the Altiplano region near to the Chajnantor Plateau. The delicate combination of elements that concurs in the Atacama region still justifies the increase in observational capabilities of solar radiation and atmospheric composition as it was first devised and executed by the pioneers of solar research in Mount Montezuma in the early twentieth century. © 2015 American Meteorological Society.