June 14, 2008

Friday 13th: ELF Prowls Low Level Jets

Today's observations kickoff our hunt (monitoring) of summer low level jets. These observations support the joint efforts of UMBC's Atmospheric Lidar Group and Maryland Department of the Environment (MDE) Air Quality Planning and Monitoring Program on educating the general public about local sources and long range transport of pollutants that affect the state of Maryland. The HYSPLIT backtrajectories shown by Ana on the previous post show that the airmasses are coming from North Carolina. Transport of smoke from North California was enhanced by the formation of a low level jet. This low level jet (LLJ) is characterized by wind speeds greater than 10m/s within the first 1.5 km of the troposphere and the air parcel that can travel >300 km up the eastern seaboard overnight to mix with the local air under the jet ensueing vertical mixing during the daytime.

The lidar timeseries (left figure) shows that after 0:00 UTC the boundary layer was inhomgeneous with stratification. Enhanced turbulent inhomogenieties observed in the residual layer are the result of LLJ activity in the boundary layer. The presence of the LLJ was also confirmed by the MDE Wind Profiler, located in Beltsville, MD (right figure). Wind speeds and direction at Beltsville were ~15 m/s SSW. Maximum wind speeds match in time with the increase of aerosol near surface observed by ELF. As soon as quality controlled wind profiler data is available we will assess the aerosol distribution within the nose/core of LLJ and transport. To be continued...

Posted by Ruben Delgado at June 14, 2008 2:46 AM
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