The University of Maryland research aircraft returned from Virginia
yesterday afternoon after completing several successful research
flights (RF-14 through RF-18) based out of Richmond, VA (RIC). The
first four flights focused on air quality over the RIC area and
Virginia Science Museum (VSM) profiler/RASS evaluation, while the last
flight investigated westerly transport to VA and MD.
Spiral locations and heights are detailed in the research flight summary for 2001.
A brief summary of preliminary results follows:
The RF-14 Tuesday 06/19 AM flight was a ferry from MD to RIC, performing profiles near Fort Meade, MD (FME) and Virginia Science Museum (VSM) profiler/RASS locations as well as upwind of the RIC metropolitan area. The planetary boundary layer (PBL) was very tightly capped under a particularly strong high-pressure ridge, and characterized by moderate haze with 16 Km visibility under clear skies. Ozone was moderate throughout the PBL and lower troposphere at 60-75 ppbv. All instruments performed nominally.
The RF-15 Tuesday 06/19 PM flight was designed to evaluate input of the RIC urban/transport corridor to in situ ozone/haze production downwind of the urban area. PBL haze had increased limiting visibility to around 10 Km under clear skies with high cirrus to the SW. Highest ozone observed was 105 ppbv uniformly through 250-1250 m MSL over New Kent County airport (W96) northeast of Richmond, VA under a strong subsidence inversion. All instruments performed nominally.
The RF-16 Wednesday 06/20 AM flight covered upwind of RIC, characterizing any "regional load" coming into the RIC area through synpotic-scale transport from locales upwind. The fine weather continued with moderate PBL haze (visibility 10-16 Km) under clear skies. Under the prevailing conditions of weak southwesterly flow at the lower levels some elevated remnant ozone (85-95 ppbv) was observed SW of RIC at 600-1200 m MSL at all profile locations. All instruments performed nominally.
The RF-17 Wednesday 06/20 PM flight was identical in design to RF-15. The ridge strength had weakened somewhat resulting in greater PBL heights than 06/19, and the higher moisture content led to some scattered fair-weather cumulus clouds filling in over the RIC area, some showing vertical development. Relative to the AM flight, profiles downwind of RIC with ozone around 100 ppbv at 300-1800 m MSL showed some evidence of in situ ozone production across the urban corridor. All instruments performed nominally.
Forecast unsettled conditions including active convection for later in the day, effectively terminated the research deployment at RIC for this event. Regional westerly-southwesterly transport to Virginia and Maryland was investigated on RF-18 Thursday 06/21 AM, an extended ferry back from RIC to home base at College Park, MD. No substantial remnnant ozone or precursor input was observed during the flight with ozone ranging from 55-70 ppbv through the altitude range studied. All instruments performed nominally. Conditions over the Baltimore-Washington corridor deteriorated rapidly during the early afternoon, and the promise of severe weather terminated aircraft operations for this episode. Over the region many 8-hour surface NAAQS ozone violations were recorded during the three days of aircraft operations, mostly in Northern Virginia and suburban Maryland downwind of the Baltimore-Washington urban corridor.
More detailed preliminary results are available from the Principal Investigator upon request.
The weekend and early next week looks quiet with respect to any significant ozone/haze episodes. However, with June 21 marking the "official" start of summer we are ready for anything. Check back early next week for an update.