Regional Atmospheric Measurement Modeling and Prediction Program (RAMMPP)

Summer 2001 Aircraft Research Update for: August 31

The University of Maryland research aircraft returned from North Carolina yesterday afternoon after completing several days conducting research flights based out Charlotte, NC - Concord Regional Airport (JQF) during a late August episode.

Spiral locations and heights are detailed in the research flight summary for 2001.

A brief summary of preliminary results follows:
The RF-62 Tuesday 08/28 Noontime flight was a ferry from MD to the Charlotte, NC (CLT) area, performing a vertical survey spiral at Franklin Co. (LHZ) downwind of Raleigh, NC (RDU) en route. The early afternoon conditions in the RDU area were characterized by moderate planetary boundary layer (PBL) haze with visibility ~5 miles under a mid-level stratus deck at near 100% cover. Some Cu clouds were observed but none showing vertical development. Throughout the flight PBL ozone increased steadily during the traverse southeast, from 50-60 ppbv over Maryland to 80 ppbv at ~800 m MSL NE of CLT. All instruments performed nominally.
Conducted later that afternoon, the RF-63 Tuesday 08/28 PM flight was designed to investigate ozone and haze production in the CLT area, particularly ozone/haze production across the CLT urban center. The flight was carried out in moderate PBL haze with visibility ~8 mi. Cu clouds were observed at ~25% cover at 6.0-7.5 Kft some showing moderate vertical development as well as scattered high Ci clouds. Ozone was moderate at 50-70 ppbv throughout most of the flight west (over Shelby, EHO) and north (over Statesville, SVH) of CLT, with highest ozone uniformly around 100 ppbv below ~1000 m MSL observed NE of CLT over Stanly Co. (VUJ). Substantial CO (~1500 ppbv at ~500 m MSL) and SO2 (6-9 ppbv at 500-1300 m MSL) were observed over EHO, probably indicative of ozone/haze precursor input upwind of CLT. All instruments performed nominally.
The RF-64 flight plan on Wednesday 08/29 AM was designed to profile in the vertical upwind (northwest) of CLT and thereby assess any regional transport of remnant ozone and ozone/haze precursors that may have occured overnight. Initially conditions were: light PBL haze with 8-10 mi visibility, scattered high Ci clouds and no Cu - with a (remnant?) haze layer observed to the W around 4.0 Kft, but by the end of the flight numerous fair wx Cu had developed through the light haze and some isolated buildups with tops ~7.0 Kft. Ozone was moderate at 45-55 ppbv throughout, with highest ozone near 70 ppbv at 1000 m MSL S of Morgantown, NC (MRN) on the traverse to EHO. At all vertical profile locations significant CO was observed trapped below the nocturnal inversion at ~600 m MSL, but perhaps more interesting in terms of haze production potential was a persistent layer of elevated SO2 just above this inversion observed likewise at all three spiral locations. All instruments performed nominally.
After a tour of the research aircraft by the Charlotte, NC media at JQF the RF-65 Wednesday 08/29 PM flight plan was designed to "box" the city of Charlotte, performing vertical spirals upwind and downwind of the city center. Ambient conditions were moderate PBL haze with visibility 6-8 mi, scattered Cu clouds with some showing development to ~9.0 Kft, under some very sparse high Ci. Highest ozone 100-105 ppbv - quite high for late August - was again observed NE of CLT, in this instance during a traverse between VUJ and SVH at ~800 m MSL, clearly downwind of CLT. During this same traverse some elevated SO2 was also observed, colocated with enhanced scattering (bscat), suggesting haze formation downwind of the CLT area. Although all instruments operated flawlessly, one of the media visitors touring the aircraft cabin apparently tripped an offset thumbwheel on the (TEI 49) ozone instrument. Tracking the problem in-flight took some time, resulting in the loss of the first 30 minutes of ozone data (including most of the first, SVH, vertical profile) during this flight.
With cooler, overcast conditions the next morning flight operations were terminated with a RF-66 Thursday 08/30 AM ferry flight from the CLT area back to College Park, MD - with an intermediate vertical survey sprial near the WRAL tower (5W5) S of Raleigh, NC. Out of CLT conditions were overcast with 100% stratus cloud cover, visibility ~5 mi, and a few scud clouds in the area causing localized showers. Ozone aloft was near seasonal norm at 50-60 ppbv throughout the flight. Low clouds forced a low-altitude limit of ~500 m MSL for the 5W5 vertical profile. Approaching the Baltimore-Washington area conditions were overcast with a stratus cloud base ~2.0 Kft, and moderate haze with visibility 4-6 mi. All instruments performed nominally.

More detailed preliminary results are available from the Principal Investigator upon request.