Effects of Clouds and Tropospheric Air Quality on Surface UV at 6 UV Research SitesEPA Grant Number: R833224
Title: Effects of Clouds and Tropospheric Air Quality on Surface UV at 6 UV Research Sites
Investigators: Lantz, Kathleen O. , Kiedron, Peter , Petropavlovskikh, Irina
Institution: Cooperative Institute for Research in Environmental Sciences
EPA Project Officer: Chung, Serena
Project Period: October 1, 2006 through September 30, 2010
Project Amount: $299,988
RFA: Implications of Tropospheric Air Pollution for Surface UV Exposures (2005) RFA Text | Recipients Lists
Research Category: Global Climate Change , Air Quality and Air Toxics , Climate Change , Air
Six locations across the continental United States will be used to evaluate the impacts of clouds and tropospheric air quality on surface UV irradiance measurements. These six sites are the re-established EPA UV Network and include Table Mountain near Boulder, CO, Rocky Mountain Research Station at Niwot Ridge, CO, Bondville, IL, Fort Peck, MT, Raleigh, NC, and Houston, TX. Our goals will be to evaluate UV-B irradiance from the six locations under a variety of atmospheric conditions.
The specific goals include (1) developing and implementing QA/QC procedures on the UV measurements and ancillary data. Procedures include comparing solar irradiance from the Brewer spectrophotometer to measurements from other co-located instruments (i.e. UV broadband radiometers and UV filter radiometers). (2) An algorithm will be developed for determining ozone profiles from Brewer Umkehr measurements and inferring tropospheric ozone column. (3) Cloud and aerosol properties will be collected from a suite of co-located instruments as part of the SURFRAD Network within the Surface Radiation Research Branch (SRRB), Earth System Research Laboratory, NOAA, and the USDA UV monitoring program. (4) Using the diffuse to direct ratio from the UV-MFRSR combined with a UV radiative transfer code, the aerosol single scattering albedo will be estimated for clear-sky conditions at the six sites. (5) The atmospheric conditions will be characterized for total ozone, cloud properties, and atmospheric pollutants. (6) We will provide a comprehensive evaluation of the impact of solar zenith angle, total ozone, cloud cover, and air quality on the tropospheric UV-B transmission. The database provided by the Central UV Calibration Facility, the Surface Radiation and Research Branch of ESRL/NOAA, and the USDA UV Monitoring Program provides a unique and valuable data-set that will help identify the impacts of variable conditions of cloud cover and tropospheric air quality on UV irradiances.
From the spectral UV solar irradiance measurements and ancillary measurements, we expect to develop an empirical formula that correlates surface UV irradiance with solar zenith angle, total ozone, cloud properties, and aerosol properties. We expect to have a better understanding of aerosol effects and cloud effects on surface UV irradiance from the analysis of the data at the six unique sites. The methods developed here and the general implications from our results will be beneficial for research in areas of UV effects on human exposure, plant productivity, and air quality.