The University of Maryland research aircraft returned from Virginia
yesterday after completing several research flights (RF-11; RF-12;
RF-13) based out of Richmond, VA (RIC). Flight operations were
terminated early due to the impending approach of unsettled weather and
instability associated with the remnant of tropical storm (TS) Allison.
Objectives of this series of flights were:
1. perform in situ evaluations of Richmond profiler/RASS data
2. investigate regional-scale pollutant transport to central Virginia
3. characterize planetary boundary layer (PBL) height, dynamics and development
4. investigate cross-corridor (I-95 transport corridor; Richmond metropolitan area) differences in air quality aloft
5. acquire in situ data for air pollution hindcasting and photochemical modeling
Spiral locations and heights are detailed in the research flight summary for 2001.
A brief summary of preliminary results follows:
The RF-11 Tuesday 06/12 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 PBL was characterized by moderate haze with about 10 Km visibility. Ozone was only slightly above climatological regional background at 60-70 ppbv. All instruments performed nominally.
The RF-12 Tuesday 06/12 PM flight was designed to evaluate input of the RIC urban/transport corridor to in situ ozone/haze production downwind of the urban area. Conditions were similar to the AM - moderate haze within the PBL, but with some fair weather cumulus (Cu) clouds scattered, some beginning to form small towers with tops around 8,500 ft. As expected, highest ozone was observed downwind of the RIC city center with 100-105 ppbv observed at around 2,000 ft over Tappahannock, VA (W79). The profile over a known "hot spot" for surface ozone locally Quinton, VA, showed 90-95 ppbv ozone throughout a well-mixed afternoon PBL reaching a maximum around 103 ppbv at 1,000 ft over the New Kent Co. airport (W96). According to Dan Salkovitz of VADEQ the surface monitor in this vicinity recorded the highest 1-hr ozone of the day, approaching the ozone NAAQS. A slight GPS serial connector problem was fixed on the ground and did not result in any flight position data loss.
The impending approach of the unsettled conditions associated precluded a more extended deployment at RIC, and delayed our RF-13 Wednesday 06/13 AM takeoff with visibilty below that legally required for VFR (visual flight rules) research flight operations. Winds had shifted slightly to the SE, bringing air more marine in character to the RIC area. This was confirmed by observations aloft from the aircraft with RH 50-60% at the lower levels within the PBL, while the lower free troposphere was rather more moist at RH 70-85% with the synoptic-scale input of TS Allison residue aloft. Consequently, observed ozone was rather low with 65-75 ppbv observed through a more-well-mixed-than-usual PBL (courtesy of the instability associated with the approaching Allison system) and Cu rapidly building below an advancing mid-level stratus cloud deck. At Fort Meade, MD (FME) on the ferry back to MD ozone aloft was elevated slightly above that observed in VA at around 85 ppbv. All instruments performed nominally on this flight.
Since it was considered unlikely that anything other than very isolated single hour high surface ozone might be seen in the Baltimore-Washington (B-W) area - and that the possibility of convective activity was much more probably - it was decided not to fly a PM plan over the B-W area.
More detailed preliminary results are available from the Principal Investigator upon request.
Early next week looks possible for the next flight operational period. Check back over the weekend for an update.