A study of the diffuse to direct solar irradiance ratio and aerosol optical depth in the southeastern US

摘要

The characteristics of aerosol optical depth and diffuse to direct solar irradiance ratio at 415, 500, 673 nm as determined by the Multi-Filter Rotating Shadowband Radiometer (MFRSR) at a regionally representative site, namely, Mt. Mitchell (35.78 deg N, 82.29 deg W, elevation 2006 m), and a site located in an adjacent valley (Black Mountain, 35.66 deg N, 82.38 deg W, elevation 951 m) in the southeastern US during the period of June 1995 to mid-December 1995 was analyzed. It is found that the representative total aerosol optical depth at 500 nm at the valley site for highly polluted (HP), polluted marine (MP) and polluted continental (CP) air masses was 0.68 +-0.33, 0.29+-0.19 and 0.10+-0.04, respectively, during the study period.