Solar Ultraviolet‐B Radiation in Urban Environments: The Case of Baltimore, Maryland¶†

Abstract

AbstractUltraviolet‐B radiation (UV‐B, 280–320 nm) has important effects in urban areas, including those on human health. Broadband UV‐B radiation is monitored in Baltimore, MD, as part of the Baltimore Ecosystem Study, a long‐term ecological research program. We compare broadband UV‐B irradiance in Baltimore with UV‐B at two nearby locations: a more rural station 64 km southeast and a suburban station 42 km southwest. The monitoring station in Baltimore is on the roof of a 33‐m‐tall building; there are no significant obstructions to sky view. The U.S. Department of Agriculture UV‐B Monitoring and Research Program provided all sensors, which were calibrated at the National Oceanic and Atmospheric Administration Central UV Calibration Facility. UV‐B irradiances at the three sites generally were similar. Over all conditions, Baltimore and the suburban site measured 3.4% less irradiance than the rural site. This difference is within the anticipated ±3% calibration uncertainty of the pyranometers. On 59 days with cloud‐free conditions at all three sites, average differences in measured UV‐B among the three sites were even smaller; Baltimore measured 1.2% less irradiance than the rural site. High aerosol optical thickness strongly reduced daily UV‐B dose, whereas [SO2] had no influence. Surface O3 increased with increasing UV‐B dose when [NO2] exceeded 10 ppb.