June 10, 2008
ELF Feels the Heat
The heat advisory issued for the Mid-Atlantic states was due to a Bermuda High (semi-permanent high pressure system).The clockwise circulation around the high pressure system brings hot, humid wind to the Eastern US. Subsidence on the Mid-Atlantic due to this system induced clear skies, high temperatures, atmospheric stability and stagnant winds. These factors enhance photochemistry and inhibit vertical mixing, thereby contributing to increased local concentrations of ozone and PM2.5. The lidar timeseries for this event shows a stratified and homogeneous boundary layer that extends up to 2 km. Code Yellow (Moderate) PM 2.5 forecasts were issued for Sunday and Monday, while a Code Orange was issued on Tuesday and was observed by ELF. The most aerosol scattering in the first 700 m of the troposphere was observed on Tuesday (red counts). PM2.5 concentrations at the Maryland's Department of the Environment during ELF's operation on Tuesday ranged from 20-42 ug/m3.