Trace-gas Measurements at the Galveston and Manvel Croix
Sites
Measurements of Trace Gases at the Manvel Croix and Galveston
Sites during DISCOVER-AQPaul Kelley1,2, Winston Luke2, Xinrong
Ren1,21Dept of Atmos. & Oceanic Sci., Univ. of Maryland2NOAA
Air Resources Laboratory
Objectives:Measurements of trace gases at the two sites in
support of DISCOVER-AQ Comparison of surface measurements with
aircraft profiling observationsOzone production efficiency using
the correlation between O3 and NOz
1
Surface Measurements at Manvel-Croix and GalvestonNOAA: NO2
based on Cavity Ring DownTCEQ: O3, NO/NOx and MetLocated to S of
downtown Houston and SW of the Houston Ship ChannelNOAA: 3-channel
NO/NO2/NOY, O3 and SO2.TCEQ: O3, NO/NOx and MetLocated to SSE of
Texas City and SW of downtown Galveston and the Port of
Galveston2Diurnal [NO2] Variation at Manvel CroixMax. [NO2] of 11
ppbv at 7:00-8:00 CST. Min. [NO2] of 1-2 ppbv in the
afternoonSlightly increasing in early evening: lower boundary
heights?
Ranged from close to zero to 29 ppbv (10-sec data)Typical
day-to-day variations with peak during morning rush hour.3Elevated
[NO2] at Manvel CroixHigh [NO2] in the winds from NE & N.
Elevated [NO2] in almost all directions: suggesting nearby local
emissions.
NO2 at Manvel Croix and Comparison with the P-3
P3 CL: chemiluminescence P3 LIF: laser induced fluorescence
Limit P-3 data at Manvel Croix: (1) below 600 m (2000 ft)(2) within
+/-0.02 Lat/Long of the siteGeneral good agreement
5P-3 [NO2] vs. surface [NO2] at Manvel CroixGood agreement in
generalMore scattered at lower [NO2] later in the day
Fractionof dayFractionof dayP-3 [O3] vs. surface [O3] at Manvel
CroixVery good agreement with little dependence on time of
day.Fractionof day
P-3 [O3] vs. surface [O3] at GalvestonGood agreement with little
dependence on time of day.Fractionof day
Limit P-3 data at Galveston : (1) below 300 m (1000 ft)(2)
within +/-0.02 Long/Lat of the site
P-3 [NO2] vs. surface [NO2] at GalvestonReasonable agreement in
general.More scattered than Manvel Croix: more horizontal/vertical
gradients due to the location of the site.Fractionof day
Wind dependence of [NOY] and [SO2] at GalvestonHighest [NOY] and
[SO2] were observed in the winds from NNE , where downtown
Galveston and the Port of Galveston are located. Galveston: [NOZ]
(= [NOY] [NOX])
Peak NOz (~1.2 ppb) in the afternoon photochemical formation.
Nighttime NOz levels: relatively constant (~0.7-0.8 ppbv).
Galveston: Ox (=O3+NO2) vs. NOzData collected from 10am to 6pm
(CST) at the surfaceSpecific for mean transport times from the
emission source regions to Galveston Assuming minimal depositional
loss of NOY species such as HNO3.
Similar slopes (14-16) using the P-3 data during the spirals at
Galveston and Smith Point. During daytime: 10am-6pm (CST)About 16
ppb O3 is created when 1 ppb NOx converted to NOy.During
DAQ-Baltimore/Washington 2011, this number is ~5-6.
12High NO2 levels at Manvel Croix were influenced by plumes from
downtown Houston and the Houston Ship Channel.
Trace gases at Galveston: relatively low levels, but influenced
by pollution plumes.
Comparisons with the P-3 data: good agreement at Manvel Croix
and more scattered at Galveston.
Estimated ozone production efficiency of ~16 ppb O3/ppb NOx
conversion at Galveston: a factor of 2-3 larger than that during
DISCOVER-AQ 2011 in the Baltimore-Washington area.Summary AQRP
& TCEQ for support
Jim Thomas, Vince Torresm, and Raj Nadkarni for logistic
support
Dave Sullivan and Maria Stanzione for project management
support
The P-3 science team for use of the aircraft data
Mark Estes for providing the TCEQ data
Russ Dickerson for loaning instrument supported by AQAST
Acknowledgements