1 Progress Report to MDE June 7, 2010 Dr. Konstantin Vinnikov, Acting State Climatologist for Maryland Prof. Russell Dickerson, Department of Atmospheric and Oceanic Science University of Maryland at College Park, MD Observed Diurnal-Seasonal Variation of PM2.5 in Maryland

Our goal is to depict the seasonal and daily cycles in SO 2 and PM2.5 and to reveal and evaluate effects of changes in Maryland Power Plants SO 2 emissions on PM2.5.

OBSERVED VARIATIONS OF PM2.5 AT MD STATIONS

DIURNAL-SEASONAL PATTERN

OBSERVED VARIATIONS OF SO 2 AT MD STATIONS

DIURNAL-SEASONAL PATTERN

MD Power Plants SO2 Emissions

PM2.5 vs. SO 2 OBSERVED PM2.5OBSERVED SO 2 MD POWER PLANTS SO 2 EMISSIONS

PM2.5 SO 2 OBSERVATIONS

Diurnal/Seasonal Variation and Variability of PM2.5 Maryland, Surface Stations Hourly Observations

Take home messages: 1.The residual layer and PBL dynamics play a major role in the daily cycle of surface concentrations of SO 2 and PM Concentrations of SO 2 peak in mid day because the major sources are aloft and vertical mixing is faster in daylight hours. 3.PM2.5 shows a major summer maximum and a minor winter maximum. 4. The winter maximum occurs at night because much of the PM is primary. 5.The summer max is broad-based because much of the PM is secondary and is transported aloft.